Quick answer: “Molex MX1.25 Board-In” is the trade shorthand for the Molex 51022 Board-in Crimp Housing family — a 1.25mm-pitch, single-row crimp housing that is soldered directly to the PCB and then loaded with crimped terminals, which is why Molex describes board-in as a connection “that does not need to be unmated on at least one end.” Molex sells the housing as the 51022 series and the matching male crimp terminals as the 50061 series (28–32 AWG) and 50080 series (26–28 AWG). Molex’s published ratings for this system are 125V maximum and 0.8A to 1.0A maximum per contact, with a housing operating temperature range of −40° to +85°C. The KONNRA equivalent is the KR1252 series, a 1.25mm-pitch board-in connector offered as a housing and a crimp terminal with 2 to 16 positions, rated 1A, documented at 125V AC/DC on the product and component pages and 50V in the series specification PDF, over −40°C to +105°C. KR1252 has no wafer — the housing itself is the board-side part, exactly as on the Molex board-in system.
At a glance
| Item | Detail |
|---|---|
| Common trade name | “Molex MX1.25” · “Molex 1.25mm” · “MX1.25 Board-In” |
| Official Molex product family | Board-in Connectors (Molex series 51022 housing, 50061 / 50080 terminals) |
| Official Molex product name | Board-in |
| Pitch | 1.25mm |
| Configuration | Single row, board-in (crimp housing mounted on the PCB; wire-side crimp terminals load into it) |
| Molex circuits | Documented by part number from 2 to 15 circuits (51022-0200 through 51022-1500) |
| KONNRA circuits | 2P to 16P |
| Molex housing material | Polyester, colour Natural |
| KONNRA housing material | Nylon66 (PA66) / UL94V-0, colour White |
| Molex terminal material | Phosphor Bronze, Tin plating |
| KONNRA terminal material | Phosphor Bronze, Tin plated over nickel |
| Molex voltage rating | 125V maximum |
| KONNRA voltage rating | 125V AC/DC (product and component pages) · 50V AC/DC in the series specification PDF |
| Molex current rating | 1.0A maximum per contact, 0.8A at 32 AWG |
| KONNRA current rating | 1A (stated at 26 AWG in the series specification PDF) |
| Molex wire range | 50061: AWG 28, 30, 32 · 50080: AWG 26, 28 |
| KONNRA wire range | AWG 26# to 32# |
| Molex wire insulation diameter | 0.50mm to 1.00mm (50061) |
| KONNRA wire insulation diameter | 1.00mm max (component pages and specification PDF) |
| Molex operating temperature | −40° to +85°C (51022 housing) |
| KONNRA operating temperature | −40°C to +105°C |
| Contact resistance | 20mΩ max — both sides |
| Insulation resistance | 100MΩ min — both sides |
| Dielectric withstanding voltage | 250V AC for 1 minute — both sides |
| Plating thickness | Molex Tin min 0.889µm (mating) and 0.914µm (termination) · KONNRA Not documented |
| Durability cycles | Molex Tin: 30 cycles (PicoBlade 1.25 system specification) · KONNRA Not documented |
| Wafer / board header | None on either side — board-in is the board-mounted part |
| KONNRA equivalent | KR1252 |
| Documents | Engineering drawing, product specification (PS-KR1252-01) and package specification, all published on the KONNRA product page |
What Is the Molex 1.25mm Board-In Connector?
Molex does not sell a product called “MX1.25”. The string is trade shorthand built from the 1.25mm pitch, and on the board-in side of Molex’s catalogue it maps to the 51022 Board-in Crimp Housing and its matching male crimp terminals. Molex’s own product name field for these parts is simply “Board-in”.
Board-in is a distinct connection architecture, and getting it straight is the first thing that decides whether your cross-reference works. In a conventional wire-to-board system a board-mounted header (a wafer) is soldered to the PCB and a wire-side housing with crimp terminals mates onto it. In a board-in system there is no separate board header: the crimp housing itself is the component that is attached at the board, and the crimped terminals are pushed into it from the wire side. Molex states the design intent directly — board-in connectors “meet the requirements of a cost-effective easy-to-assemble connection that does not need to be unmated on at least one end.”
That single sentence explains everything that follows about this family:
- There is no wafer in the bill of materials. Molex’s 51022 part pages list the housing and the crimp terminals, not a header. KONNRA’s KR1252 product page is structured the same way: it offers a terminal and a housing, and its series specification PDF states Wafer is None.
- The number of pieces per connection is lower. One housing plus the terminals replaces a housing, a header and the solder joint that would otherwise carry the interface.
- Serviceability is the trade-off. Molex’s own wording is that at least one end does not need to be unmated. If your design has to be plugged and unplugged repeatedly at both ends, a board-in part is the wrong family and you want the wire-to-board PicoBlade system instead.
- Mating geometry is vertical. Molex’s 51022 housing is described as “Board-In Crimp Housing, Vertical”, and the male crimp terminals are also described as “Vertical”.
A note on the name, because it costs people money. “MX1.25” gets used for two entirely different Molex things. The board-in parts are 51022 / 50061 / 50080. The classic wire-to-board and wire-to-wire parts are the PicoBlade family — receptacle housings 51021, receptacle crimp terminals 50079 and 50058, and plug assemblies such as 53047 and 53048. Both are 1.25mm. They do not share a housing. If a drawing or a distributor listing says “1.25mm Molex” and nothing else, the pitch does not tell you which family you have.
A short glossary, because this family uses all of these terms
- Board-in — a connection where the crimp housing is mounted at the board and the crimped wire terminals load into it, with no separate board header. Molex’s product name for the 51022 family.
- Crimp housing — the plastic body that holds the terminals. On this system it is the board-side part (Molex 51022, KONNRA KR1252 housing). Molex classifies 51022 under Product Family “Crimp Housings”.
- Male crimp terminal — the contact crimped onto the wire. Molex 50061 is documented as “1.25mm Pitch, Board-in Male Crimp Terminal, Vertical, 28–32 AWG, Reel, for 51022 Housing”; Molex 50080 is documented as “1.25mm Pitch Board-In Crimp Terminal, 26–28 AWG, Reel, for 51022 Housing”.
- Wafer / header — the board-mounted pin block used by wire-to-board systems. Not present here. KONNRA’s KR1252 specification PDF lists “Wafer: None”.
- Pre-crimped lead — a factory-terminated wire ready to be loaded into the housing. Molex lists PicoBlade Board-In Pre-Crimped Leads 797581062 and 797581063 as parts used with the 51022 housing.
- Insulation O.D. — the outside diameter of the wire’s insulation jacket. This is the dimension the crimp barrel must swallow, and on a 1.25mm connector it is a real constraint rather than a formality.
- Positions / circuits — the number of contact positions in the housing. Molex and KONNRA both quote this per part number.
- Polarization — keying that stops the housing being loaded the wrong way round. Confirm it exists on the specific part you order; it is not stated on every datasheet row.
- UL94V-0 — a flammability classification for the plastic. KONNRA states it for the KR1252 housing; Molex’s 51022 part datasheet reviewed for this guide does not list a flammability rating.
Molex Board-In 1.25mm and KONNRA KR1252 Specifications
| Parameter | Molex board-in 1.25mm (Molex documentation) | KONNRA KR1252 (KONNRA documentation) |
|---|---|---|
| Pitch | 1.25mm (Molex 51022: “Pitch – Mating Interface 1.25mm”) | 1.25mm |
| Row configuration | Single row (Molex 51022: “Number of Rows: 1”) | Single row |
| Connection type | Board-in (housing mounted at the board, no wafer) | Board-in (category field on both the terminal and the housing page) |
| Mating direction | Vertical | Vertical |
| Circuits | 2 to 15, by part number (51022-0200 to 51022-1500) | 2P to 16P |
| Voltage rating | 125V maximum | 125V AC/DC on the product page and both component pages; 50V AC/DC in the series specification PDF (PS-KR1252-01, clause 4.0) |
| Current rating | 1.0A maximum per contact; 0.8A at 32 AWG | 1A, stated as 1A (26 AWG) in PS-KR1252-01 |
| Applicable wire | 50061: AWG 28, 30, 32 · 50080: AWG 26, 28 | AWG 26# to 32# |
| Wire insulation diameter | 0.50mm to 1.00mm (50061) | 1.00mm max (component pages and PS-KR1252-01) |
| Contact material | Phosphor Bronze | Phosphor Bronze |
| Contact plating | Tin; plating minimum 0.889µm (mating) and 0.914µm (termination) | Tin plated over nickel; thickness Not documented |
| Housing material | Polyester | Nylon66 (PA66), UL94V-0 |
| Housing colour | Natural | White |
| Contact resistance | 20mΩ max | 20mΩ max |
| Insulation resistance | 100MΩ min (500V DC) | 100MΩ min (500V DC, 1 minute) |
| Dielectric withstanding voltage | 250V AC (rms) for 1 minute | 250V AC for 1 minute |
| Temperature rise | 30°C max | 30°C max |
| Operating temperature | −40° to +85°C | −40°C to +105°C |
| Durability | 30 cycles (Tin plated, PicoBlade 1.25 system specification) | Not documented |
| Packaging | Bag (51022 housing); Reel (50061, 50080) | Package specification published (Package-spec_KR1252) |
| Standard | UL File E29179 (PicoBlade 1.25 system specification) | UL E482542 |
| Wafer | Not applicable | None |
| RoHS | EU RoHS Compliant; REACH SVHC not contained (per D(2020)9139-DC, 19 Jan 2021); halogen-free status: not low-halogen | Not documented in the sources reviewed for this guide |
Where a cell says “Not documented”, the parameter is not stated in the manufacturer documentation reviewed for this guide. Confirm any blank against the current Molex datasheet and the KR1252 product specification before releasing a drawing.
Figure 1 — KONNRA KR1252 series 1.25mm board-in connector
➡️ View the KONNRA KR1252 1.25mm board-in connector
The header row of that table hides one important thing, so it is worth separating out. Molex’s board-in figures are published on two different levels: the housing page gives the mechanical and environmental envelope (pitch, rows, material, colour, temperature range), and the terminal page gives the electrical and wire envelope (current, voltage, wire size, insulation diameter, plating). KONNRA publishes its KR1252 data on three levels — a product page with a General Specification table, two component pages, and the specification PDF. The product page and the specification PDF do not agree with each other on voltage, and the product page and the specification PDF do not agree with each other on wire insulation diameter. Both of those are set out in the differences section below.
Molex 51022 = KONNRA KR1252: Part Number Cross-Reference
| Molex board-in component | Molex part number | KONNRA equivalent |
|---|---|---|
| Board-in crimp housing, vertical | 51022 series — for example 51022-0200 (2 circuits), 51022-0300 (3), 51022-0400 (4), 51022-0500 (5), 51022-0600 (6), 51022-1000 (10), 51022-1500 (15) | KR1252 housing |
| Board-in male crimp terminal, 28–32 AWG | 50061 series — 50061-8000 (reel), 50061-8100 (loose) | KR1252 terminal |
| Board-in crimp terminal, 26–28 AWG | 50080 series — 50080-8000 (reel), 50080-8100 (loose) | KR1252 terminal |
| Pre-crimped lead | PicoBlade Board-In Pre-Crimped Lead 797581062, 797581063 | Built to order |
| Wafer / board header | Not applicable to board-in | None |
The KONNRA side is documented as two orderable components, each with its own page and drawing:
| Component | KONNRA page | Compatible Molex series stated by KONNRA |
|---|---|---|
| Terminal | KR1252 Terminal | 50080 Series |
| Housing | KR1252 Housing | 51022 Series |
Note the asymmetry in that last column. KONNRA’s housing page names the Molex 51022 series, which is correct — 51022 is the board-in housing. KONNRA’s terminal page names the Molex 50080 series, but the KONNRA terminal’s own documented wire range is AWG 28# to 32#, and in Molex’s catalogue 28–32 AWG is the 50061 range — 50080 is the 26–28 AWG part. So the component page points at the wrong half of the Molex terminal pair for its own published wire range. That is a documentation mismatch rather than an electrical one, but it is exactly the kind of thing that ends up on a BOM, so it is worth resolving in writing.
There is a second reason to be careful about 50080 specifically. Molex’s part page for 50080-8000 lists the series as Obsolete, with “Replacement: Contact Molex”, and points to 50080-8100 as the loose-packaging alternative. An older distributor snapshot of the same part (dated 2013) still shows the status as Active. If your cross-reference target is 50080 and the housing is being kept in production for a long-life programme, confirm what Molex currently recommends before you build a second-source plan around it.
How to read a board-in part number
Molex’s 51022 numbering is short and readable. The series is 51022, and the trailing digits identify the circuit count and packaging: 51022-0200 is 2 circuits, 51022-0500 is 5 circuits, 51022-1500 is 15 circuits. Molex’s own part descriptions spell this out — “1.25mm Pitch, Board-In Crimp Housing, Vertical, 2 Circuits, Natural”.
Terminal numbering follows the same shape but the dash position carries the wire-size family: 50061-8000 is the reel version for 28–32 AWG and 50061-8100 is the loose version of the same terminal; 50080-8000 is the reel version for 26–28 AWG and 50080-8100 is the loose version. Molex labels 50061-8100 as the “Packaging Alternative” for 50061-8000, which confirms the pattern — the last four digits encode wire range plus packaging, not just sequence.
KONNRA’s internal part numbers use a house format rather than the Molex format. The KR1252 specification PDF lists the housing as H1252010101A and the terminals as T12520PT0101A and T12520PT0102A. Two terminal part numbers for one series is consistent with what Molex does — two wire-size variants of the same male terminal. Note also that the same PDF lists the wafer as None, which is the clearest possible statement that KR1252 is a board-in part and not a wire-to-board kit.
What to do if your drawing shows a partial or unfamiliar number: send it anyway. KONNRA will confirm the pitch, the position count and the wire range against the board-in system before quoting. On a 1.25mm family this is faster than working it out alone, because 1.25mm board-in (51022), 1.25mm PicoBlade wire-to-board (51021 and its plug assemblies) and 1.25mm CLIK-Mate or PanelMate all look like neighbours in a parts list and none of them share a housing.
The 1.25mm Family: Board-In Is One Branch, Not the Whole Tree
Molex runs several different 1.25mm systems. They share a pitch and nothing else, and the trade name “MX1.25” is used loosely for all of them.
| Connector system | Molex series | Pitch | Configuration | KONNRA equivalent |
|---|---|---|---|---|
| Board-in | 51022 housing, 50061 / 50080 terminals | 1.25mm | Board-in, vertical, no wafer | KR1252 |
| PicoBlade wire-to-board | 51021 housing, 50079 / 50058 terminals, plug assemblies 53047 / 53048 | 1.25mm | Wire-to-board, vertical and right-angle, plus wire-to-wire | KR1250 (wire-to-board) and KR1251 (wire-to-wire) |
| CLIK-Mate wire-to-board | 502380 housing family | 1.25mm | Wire-to-board, single row, positive lock | No equivalent documented against KR1252 |
| PanelMate wire-to-board | 51146 housing family | 1.25mm | Wire-to-board, ultra low profile | No equivalent documented against KR1252 |
What this table settles:
- “1.25mm” is not a part number. Board-in, PicoBlade, CLIK-Mate and PanelMate all sit at 1.25mm pitch and none of them is interchangeable with another.
- Board-in is the only one of the four with no wafer. If your drawing shows a board-mounted header plus a wire-side housing, you do not have a board-in design, and KR1252 is the wrong part — you want the wire-to-board branch.
- The KONNRA family splits the same way. KR1252 is the board-in branch; KR1250 and KR1251 serve the PicoBlade wire-to-board and wire-to-wire interfaces. A 1.25mm enquiry that does not say which of those three architectures it is cannot be answered from the pitch alone.
- Locking is the other divider. Board-in parts have no separate latch to release because at least one end is not meant to be unmated, per Molex’s own description of the family. The wire-to-board members of the 1.25mm tree are the ones you look at when repeated mating is a requirement.
Specification Differences to Verify Before You Cross-Reference
Twelve points deserve attention before you sign off an MX1.25 board-in cross-reference. They are listed in the order they tend to cause damage.
- The voltage rating disagrees inside KONNRA’s own documentation. KONNRA’s product page table states Voltage 125V and its Overview paragraph says “voltage ratings up to 125V AC/DC”; both component pages state Operating Voltage 125V. The series specification PDF, PS-KR1252-01 clause 4.0, states “Rated Voltage (Max.) 50V AC/DC”. Molex publishes 125V maximum for the 50061 board-in terminal. Two of KONNRA’s three published levels agree with Molex and the third does not, and the third is the document an engineer is most likely to attach to a drawing. Resolve this in writing if your application runs above 50V, or if the receiving inspection document will be the specification PDF.
- The dielectric withstanding voltage agrees — and this is worth stating explicitly, because on other KONNRA series this row is filled in wrongly. The KONNRA product page states Withstanding Voltage 250V AC/minute, and PS-KR1252-01 clause 5.3 states 250V AC for 1 minute between adjacent terminals or terminal and ground, with the requirement “no breakdown and flashover”. Molex specifies 250V AC (rms) for 1 minute as the dielectric strength test for the 1.25mm PicoBlade system specification. So 250V is a dielectric test value on both sides, not a misplaced copy of the 125V rating — the numbers are consistent. The one caveat is document provenance: the 250V AC figure on the Molex side comes from the PicoBlade 1.25 connector system product specification, because Molex’s board-in product specification PS-51022-001 / PS-51022-002-001 is referenced from Molex’s part pages but the PDF itself was not retrievable for this guide.
- The operating temperature range differs by 20°C. Molex documents −40° to +85°C for the 51022 housing. KONNRA documents −40°C to +105°C on both component pages and in the specification PDF, and its environmental test schedule backs the upper figure with a heat-resistance test at 105±2°C for 96 hours. The KONNRA part is claimed over a wider window than the Molex part. KONNRA’s own heat-ageing test is run at exactly 105°C, so there is no margin above the claim — if your application runs near 105°C continuously, treat the upper limit as a hard ceiling and confirm it for your assembly rather than assuming headroom.
- Housing material is different. Molex specifies Polyester for the 51022 housing. KONNRA specifies Nylon66 (PA66) with a UL94V-0 flammability rating. These are different polymers with different moisture uptake, different dimensional behaviour under thermal cycling and different reflow tolerance. KONNRA does state UL94V-0; Molex’s 51022 part datasheet reviewed for this guide does not state a flammability rating at all, so do not read the comparison as “Molex is unrated and KONNRA is V-0” — read it as “the two materials are different and one of them carries a published V-0 claim”.
- Plating thickness is specified by Molex and not by KONNRA. Molex documents Tin plating with a minimum of 0.889µm on the mating area and 0.914µm on the termination area for 50061. KONNRA documents “Tin over nickel” for the terminal and “Tin over Nickel” in the product page general specification table, with no thickness for either layer. Tin-over-nickel is a different construction from tin directly on phosphor bronze, and it is not equivalent in porosity or in long-term contact stability. If contact finish matters to your qualification, ask for the thickness of both the tin and the nickel layer in microns.
- Circuit count runs one position wider on the KONNRA side. Molex’s 51022 catalogue documents housings from 2 circuits (51022-0200) up to 15 circuits (51022-1500). KONNRA documents 2P to 16P on both the product page and the housing component page. Either KONNRA offers a 16-position board-in housing that Molex does not, or the range describes something else. Confirm the exact position count before it reaches a drawing.
- The wire range is documented differently on the two sides, and inconsistently on the KONNRA side. Molex splits the wire envelope across two terminals: 50061 covers AWG 28, 30 and 32, and 50080 covers AWG 26 and 28. KONNRA states AWG 26# to 32# in PS-KR1252-01 and in the product page Overview paragraph, but AWG 28# to 32# on both component pages. A single-range claim over 26–32 AWG implies one terminal part number covers what Molex needs two part numbers to cover. The KONNRA specification PDF does list two terminal part numbers, T12520PT0101A and T12520PT0102A, which is consistent with a split — but the split is not stated. Ask which KR1252 terminal part number applies to 26 AWG and which to 32 AWG.
- Current derating by wire gauge is published by Molex and not by KONNRA. Molex gives “Current – Maximum per Contact 0.8A, 1.0A” for 50061, and the 1.25mm system specification lists 1.0A for AWG 26, 28 and 30 with 0.8A for AWG 32, plus a derating table by circuit count (for example 1.0A at 30 AWG in a 15-circuit housing). KONNRA states 1A with the parenthetical “(26 AWG)” in PS-KR1252-01 and no derating table by position count. If you are running close to 1A in a high-position-count housing, the derated value, not the headline value, is the number your design has to satisfy.
- Wire insulation diameter is stated inconsistently by KONNRA. PS-KR1252-01 and both component pages state applicable wire insulation O.D. 1.00mm max. The product page General Specification table states “Insulation O.D 1.25mm” — the same number as the pitch. Molex documents 0.50mm to 1.00mm for the 50061 terminal. The 1.00mm figure appears in three KONNRA places and the 1.25mm figure in one, and the 1.25mm figure matches the pitch, so treat it as a probable transcription artefact and confirm which limit applies to your cable.
- Mating durability is published by Molex and not by KONNRA. The 1.25mm PicoBlade system specification states 30 cycles for tin-plated parts. KONNRA publishes no cycle count for KR1252. On a board-in connector the durability question is narrower than on a mating pair — the interface is not designed for repeated unmating — but if the housing will be loaded and re-loaded during assembly rework, ask for a figure.
- Colour differs. Molex documents the 51022 housing as Natural, which is the off-white of unfilled polymer. KONNRA documents White for the KR1252 housing. This has no electrical consequence and one practical one: colour is what an operator uses to identify a housing at a glance on the line, and a change of colour between the original and the second source is a training item.
- The crimp specification is published in detail by KONNRA and not for the board-in terminal by Molex. KONNRA’s specification PDF gives crimp width 0.85±0.1mm, crimp height bands per gauge for conductor and insulation crimps, minimum crimp strength of 1.36 / 0.9 / 0.7 kgf for 28 / 30 / 32 AWG, and a strip length of 1.1 to 1.5mm. That level of detail is genuinely useful for a harness builder. Molex publishes its crimp tooling and applicator data separately from the product specification, so the two documents are not directly comparable — which is why the tooling question is on the checklist further down rather than in this list.
Design and Usage Notes for a 1.25mm Board-In Interface
A board-in connector changes the mechanical design brief, not just the bill of materials. Six things follow from the architecture.
The housing is a board component, so its footprint and its process are yours. There is no header to solder and no second solder joint, but the housing itself is now a mechanical part of the assembly. Molex describes the 51022 housing as vertical, and the terminal as vertical, so the wire exits perpendicular to the board. If your enclosure was designed around a right-angle cable exit, the interface geometry is wrong and no amount of pitch matching will fix it.
Crimp quality becomes a board-level reliability issue. With no header, the crimp is the only compliant joint between the wire and the board. KONNRA specifies that crimp in unusual detail — height bands for both the conductor and the insulation crimp, and a minimum crimp strength of 1.36kgf at 28 AWG falling to 0.7kgf at 32 AWG. Those numbers are the acceptance criteria for your harness supplier, and they are worth putting in the purchase order rather than leaving to the harness house’s default.
Retention is specified, and it is small. KONNRA documents terminal insertion force at 0.5kgf (4.9N) maximum and terminal-to-housing retention at 0.7kgf (6.86N) minimum. Both are single-digit newtons. On a 1.25mm contact that is normal, but it means the wire must not be loaded in tension and must be strain-relieved at the harness level. Molex’s board-in family description reinforces the same point from the other direction: the connection is not intended to be unmated at one end.
Insulation diameter is a real constraint at this pitch. 1.25mm pitch with a 1.00mm maximum insulation outside diameter leaves very little room between adjacent wires. A heavier jacket that passes the crimp barrel can still cause the wires to bear on each other across the contact field. Measure the jacket, not the conductor, and check the daisy-chain case — a 16-position housing with full-gauge wire is the tightest configuration in the family.
Assembly sequence matters more than usual. Because the housing is loaded from the wire side after it is on the board, the crimped terminals must be inserted with the housing already in place on the PCB, or the loaded housing must be handled as a populated assembly. Whichever route your line takes, the 0.5kgf maximum insertion force becomes a process limit — a terminal that needs more than that to seat is not a terminal that should be pushed harder.
Ask what the housing is mounted to. Molex’s board-in notes and KONNRA’s specification both stop short of describing the mechanical attachment in the documentation reviewed for this guide. KONNRA’s KR1252 specification PDF adds one concrete detail — a solderability test at 245±5°C for 3±0.5 seconds with a requirement that 95% of the immersed area shows no voids or pin holes, which is a solderable-terminal test — even though the KR1252 bill of materials lists only a housing and a terminal. If your process depends on how the housing is fixed to the board, confirm it against the KR1252 engineering drawing rather than inferring it from the test list.
Components and Configuration Options
KR1252 is specified as two separately orderable components, each with its own page, drawing and documented range of positions — which is what lets the same series cover both a connector-only order and a fully assembled harness order.
| Component | Component page | Product drawing | Position range | Wire range |
|---|---|---|---|---|
| Housing | KR1252 Housing | KR1252-H | 2P to 16P | AWG 28# to 32# |
| Terminal | KR1252 Terminal | KR1252-T | Not applicable | AWG 28# to 32# |
| Wafer | None | None | Not applicable | Not applicable |
Housing (the board-side half)
On a board-in connector the housing is the component that sits at the board, and the wire-side crimped terminals load into it. KONNRA documents the KR1252 housing as: Category Board In, Single row, 2P to 16P positions, colour White, material Nylon66 with a UL94V-0 rating, operating voltage 125V, current 1A, contact resistance 20mΩ max, insulation resistance 100MΩ min, wire range AWG 28# to 32#, operating temperature −40°C to 105°C, and UL file E482542. Its stated compatible Molex series is 51022.
Figure 2 — KONNRA KR1252 board-in housing, 1.25mm pitch
➡️ KR1252 Housing component page
Two things to check on the housing before you commit a footprint. First, position count: KONNRA documents 2P to 16P, while Molex’s 51022 catalogue documents 2 to 15 circuits. Second, material: KONNRA specifies Nylon66 with UL94V-0, Molex specifies Polyester for 51022. If your board goes through reflow with the housing fitted, the polymer change is a process question, not a datasheet footnote — and if the housing is fitted after reflow, it is not.
Figure 3 — KR1252 housing detail: 1.25mm pitch, single row, 2 to 16 positions
Terminal (the wire-side half)
KONNRA documents the KR1252 terminal as: Category Board In, Assembly type Terminal, pitch 1.25mm, operating voltage 125V, current 1A, contact resistance 20mΩ max, insulation resistance 100MΩ min, insulation diameter 1.00mm max, wire size AWG 28# to 32#, operating temperature −40°C to 105°C, and UL file E482542. Its stated compatible Molex series is 50080.
The series specification PDF adds material and finish — Phosphor bronze, Tin plated over nickel — and two terminal part numbers, T12520PT0101A and T12520PT0102A.
Figure 4 — KONNRA KR1252 board-in crimp terminal
➡️ KR1252 Terminal component page
Three things to confirm on the terminal. The wire range is stated as AWG 26# to 32# in PS-KR1252-01 and in the product page Overview paragraph, and as AWG 28# to 32# on both component pages — the two documents do not agree with each other. The compatible Molex series is stated as 50080, but 28–32 AWG is Molex’s 50061 range rather than 50080’s 26–28 AWG. And the plating is documented as tin over nickel with no thickness, against Molex’s stated minimums of 0.889µm on the mating area and 0.914µm on the termination area.
Figure 5 — KR1252 terminal detail, 1.25mm pitch
Crimp and process data published by KONNRA
This is the part of the KR1252 documentation that is more detailed than the Molex part datasheet, and it is the part a harness house needs:
| Crimp parameter | Value (PS-KR1252-01, clause 6.3) |
|---|---|
| Conductor crimp width | 0.85±0.1mm |
| Conductor crimp height | 0.50–0.60mm at 28 AWG · 0.45–0.55mm at 30 AWG · 0.40–0.50mm at 32 AWG |
| Insulation crimp width | 1.00mm max |
| Insulation crimp height | 1.15mm max at 28 AWG · 1.05mm max at 30 AWG · 0.85mm max at 32 AWG |
| Crimp strength | 1.36kgf min at 28 AWG · 0.9kgf min at 30 AWG · 0.7kgf min at 32 AWG |
| Strip length | 1.1 to 1.5mm |
| Terminal insertion force | 0.5kgf (4.9N) max |
| Terminal / housing retention force | 0.7kgf (6.86N) min |
Series documentation
- KR1252 series engineering drawing (PDF)
- KR1252 product specification PS-KR1252-01 (PDF)
- KR1252 package specification (PDF)
- KR1252 terminal product drawing and KR1252 housing product drawing
➡️ Request drawings for your specific position count and wire gauge
What the 1.25mm Board-In Connector Is Used For
Molex positions board-in as the connection type for designs that need a cost-effective, easy-to-assemble joint that does not need to be unmated on at least one end, and compares it against hand-soldering and against other board-in types, where Molex claims the widest range of pitch options, mating configurations and circuit sizes. KONNRA lists the KR1252 series for computers, radio systems, automotive electronics and medical equipment.
That is a broad list, and the architecture narrows it further. Board-in wins where the wire is going to enter an assembly once and stay there.
| Application | Why a board-in 1.25mm interface fits |
|---|---|
| Internal sub-assembly wiring in computers and peripherals | A single-row 1.25mm housing keeps the board footprint small, and there is no header to place or solder |
| Radio and communications boards | Molex classes the 51022 application as Signal; a 1A signal interface at 125V covers typical internal signal and low-power runs |
| Automotive electronics modules | Molex’s board-in family is part of its transportation catalogue; the −40°C cold end is the relevant figure for in-cabin and under-dash electronics |
| Medical equipment and instruments | KONNRA lists medical equipment and holds an ISO13485 medical device quality system where the product falls in that scope |
| Sensor and lighting sub-boards where the harness is dressed once at build | The connection is not intended to be unmated at one end, which is exactly the case for a harness that is fitted at final assembly |
| Appliances and small motorised products | 1A per contact at 125V covers control and signalling functions at a low piece count |
| Any board where a wafer would be the tallest or most fragile component | Removing the header removes the tallest part of the interface and one solder joint |
| Designs moving away from hand-soldered wire tails | Board-in replaces a hand-soldered tail with a crimped, inspectable connection |
What it is not for. It is not a high-current connector: 1A per contact is a signal-and-low-power rating, and Molex’s own 1.25mm board-in terminal is additionally limited to 0.8A at 32 AWG. It is not a repeatedly mated interface, because the architecture is designed so that at least one end stays put. And it is not a wire-to-board system — if you need a board header with a plug, you want the PicoBlade branch of the 1.25mm family, not this one.
Cable Assembly and Harness Options
Board-in housings are typically supplied loaded with crimped terminals from the harness side rather than as an empty housing for the line to populate. KONNRA builds assemblies on the 1.25mm board-in interface in the standard harness configurations:
| Cable type | Description | Typical use |
|---|---|---|
| Single-headed | Housing on one end, bare wire leads on the other | Board-in housing at the board, tails terminated into a terminal block or another housing elsewhere |
| Same-side-head | Housing on both ends, same orientation | A board-to-board run where both ends are populated by housing |
| Reverse-side-head | Housing on both ends, reversed orientation | Routing through a hinge, fold or a tight bend radius |
| Adapter and transition cables | KR1252 board-in on one end, another 1.25mm interface on the other — for example KR1252 to the PicoBlade wire-to-board branch, or to a CLIK-Mate or PanelMate interface | Where one board uses a board-in housing and the other does not |
Adapter harnesses are a common MX1.25 enquiry for a structural reason rather than a commercial one. Board-in, PicoBlade, CLIK-Mate and PanelMate all sit at 1.25mm pitch and share no housing, so when one board in a product uses a board-in housing and the other uses a plug-in 1.25mm interface, the transition has to happen inside the cable. Molex solves part of this itself with the PicoBlade Board-In Pre-Crimped Leads 797581062 and 797581063, which are ready-made leads that plug into the board-in housing — worth knowing about if your board-in side is a Molex original and only the other end is being re-sourced.
Tension is the design constraint on every one of these harnesses. With retention documented at 0.7kgf (6.86N) minimum and no latch, the harness needs strain relief and a defined service loop, and the cable tie location should be specified on the drawing rather than left to the line. Molex’s own 1.25mm system specification devotes a clause to exactly this — cable tie and twist tie location — which is a good indication of how much it matters at this pitch.
Connector lead time is typically 2–3 weeks; wiring harness lead time is typically 3–4 weeks. Key materials are prestocked.
➡️ Explore KONNRA wiring harness capabilities
Sourcing the 1.25mm Board-In Connector: What Procurement Teams Ask
Engineering decides that a connector will work. Procurement decides whether the supply chain around it is safe, and on a board-in part the second question is sharper than usual because the cross-reference target itself is partly obsolete.
“Can you be a second source without changing our design?” That is what a documented cross-reference is for, and KR1252 is specified against the Molex board-in system at component level: the KONNRA housing page names Molex 51022, the terminal page names Molex 50080, and the pitch, row count, contact resistance and insulation resistance all match. It is not a drop-in in every respect — housing material, operating temperature and plating construction differ, and the voltage rating inside KONNRA’s own documentation is stated two ways. We confirm equivalence against your specific part number, because position count, wire gauge and plating all change the answer.
“Is our original part still available?” Worth asking yourself first. Molex’s part page for 50080-8000 lists the series as Obsolete with “Replacement: Contact Molex”, even though an older distributor snapshot still shows it as Active. If your drawing calls out 50080, the second-source conversation is not optional.
“What are your lead times?” Connector production lead time is typically 2–3 weeks. Wiring harness lead time is typically 3–4 weeks. Key materials are prestocked.
“How long for samples?” Complete connector set samples can be delivered within 45 days. Where you need to validate crimp quality or a cable assembly before committing, sample harnesses can be supplied from the same process used in production — which matters more on a board-in part, where the crimp is the only compliant joint to the board.
“What qualifications do you hold?” ISO9001, ISO14001, IATF16949, ISO45001:2018, ISO13485, IPC620, and UL product and operational safety certifications. Automotive-grade series additionally hold LV214 and US CAR-2.
“How do we know the parts match your documentation?” A CNAS-accredited laboratory with 45+ sets of precision testing instruments, with dimensional and electrical verification data available on request. 95% of production processes carry full-line intelligent visual CCD inspection; automotive series receive 100% CCD inspection.
“Are you a manufacturer or a trader?” A manufacturer. Dongguan Konnra Electronics Co., Ltd., founded 2004, with in-house mould design, injection moulding, stamping, assembly, and inspection — so the connector and the cable assembly come from one quality system.
“What volumes can you support?” KONNRA reported 2025 sales of RMB 310 million, with connectors at 60% and wiring harnesses at 40% of the product mix, across four production bases with automation coverage exceeding 95%.
➡️ Request the vendor qualification pack — certificates, test capability summary, product drawings, and a sample plan in one enquiry.
How to Get a Cross-Reference Check on Your MX1.25 Board-In Part Number
Most MX1.25 board-in enquiries stall on the same thing: the buyer is not sure what information the supplier needs, so the enquiry never gets sent. Here is the complete list.
Send us:
- The original Molex part number if you have it — the housing such as 51022-0200 or 51022-1500, or the terminal such as 50061-8000 or 50080-8000
- Position count, and remember Molex’s 51022 catalogue documents 2 to 15 circuits while KONNRA documents 2P to 16P
- Whether you need the housing only, the terminals only, or a loaded housing and a finished harness — the KR1252 bill of materials has no wafer, so the answer changes what you order
- Wire specification — gauge and insulation outside diameter. KONNRA documents AWG 26# to 32# with insulation 1.00mm max, and Molex documents 0.50mm to 1.00mm for 50061, so the jacket diameter is not optional information on this series
- Your load current, not just the connector rating. If it is close to 1A in a high-position-count housing, say so — the derated value is what the design has to satisfy
- Your circuit voltage, so the 125V versus 50V discrepancy in KONNRA’s own documents can be resolved against your application instead of left open
- Operating temperature requirement, because the Molex housing is documented to +85°C and the KONNRA part to +105°C and the difference matters in either direction
- Application and annual volume, so configuration, tooling and packaging can be matched to your programme
- A drawing or photo, if the part number is unreadable or the design has been reverse-engineered
When you send a part number, we will confirm four things against Molex’s own documentation: the position count, the wire gauge the terminal is validated for, the insulation diameter window, and the plating construction you need. Those four are where an MX1.25 board-in cross-reference most often goes wrong.
What you get back: a mapped KONNRA part number with the relevant product and engineering drawings, a specification comparison against your original part, and a sample and quote plan.
Engineer’s Pre-Release Checklist
Run this before you release a drawing for a 1.25mm board-in connector.
- Pitch measured, not assumed. 1.25mm covers board-in (Molex 51022), PicoBlade wire-to-board (51021 and its plug assemblies), CLIK-Mate (502380) and PanelMate (51146). None of them shares a housing.
- Architecture confirmed. Board-in means the crimp housing mounts at the board and there is no wafer. If your drawing shows a board header plus a wire-side plug, you do not have a board-in design and KR1252 is the wrong family.
- Position count confirmed against what each side actually documents. Molex’s 51022 catalogue runs 2 to 15 circuits by part number; KONNRA documents 2P to 16P.
- Voltage rating resolved in writing. KONNRA states 125V on the product page and both component pages and 50V in PS-KR1252-01 clause 4.0; Molex publishes 125V maximum for 50061. If your application runs above 50V, get the figure confirmed on the document your drawing will reference.
- Dielectric withstanding voltage confirmed as a test value, not a rating. KONNRA states 250V AC for 1 minute in PS-KR1252-01 and 250V AC/minute on the product page, and that agrees with the 250V AC (rms) dielectric strength in Molex’s 1.25mm system specification. This one is consistent on both sides.
- Current rating checked against your wire gauge. Molex documents 1.0A maximum per contact with 0.8A at 32 AWG, and a derating table by position count. KONNRA states 1A, stated at 26 AWG, with no derating table. Do not assume the headline figure applies at 32 AWG or at 16 positions.
- Wire gauge and insulation diameter inside the documented window. KONNRA documents AWG 26# to 32# with insulation 1.00mm max; Molex documents 0.50mm to 1.00mm for the 50061 terminal. Note the KONNRA product page General Specification table states Insulation O.D 1.25mm, which matches the pitch and disagrees with the other three KONNRA sources — resolve it against your actual cable.
- Operating temperature checked. Molex specifies −40° to +85°C for the 51022 housing. KONNRA specifies −40°C to +105°C, and its own heat-ageing test is run at 105±2°C for 96 hours, so there is no published margin above the claim.
- Housing material checked against your process. Molex specifies Polyester; KONNRA specifies Nylon66 with UL94V-0. A polymer change is a process question if the housing sees reflow or a wash.
- Plating thickness confirmed in microns. Molex documents Tin at 0.889µm minimum on the mating area and 0.914µm on the termination area. KONNRA documents tin over nickel with no thickness for either layer.
- Retention and strain relief designed, not assumed. KONNRA documents terminal insertion force at 0.5kgf (4.9N) max and terminal-to-housing retention at 0.7kgf (6.86N) min, with no latch. Specify the cable tie or twist tie location on the drawing.
- Crimp acceptance criteria passed to the harness house. KONNRA publishes crimp width 0.85±0.1mm, per-gauge conductor and insulation crimp heights, minimum crimp strength of 1.36 / 0.9 / 0.7 kgf at 28 / 30 / 32 AWG, and strip length 1.1 to 1.5mm. On a board-in part the crimp is the only compliant joint to the board, so put these in the purchase order rather than leaving them to default.
- Backward compatibility of your original part number checked. Molex’s part page for 50080-8000 lists the series as Obsolete with “Replacement: Contact Molex”; an older distributor snapshot still shows Active. Confirm the current status before freezing the reference.
- Mating durability confirmed if the housing will be re-loaded in service or rework. Molex publishes 30 cycles for tin-plated 1.25mm parts; KONNRA publishes no cycle count for KR1252.
➡️ Send us your drawing. We will review it against the KR1252 specification and come back with any mismatch we find — before you commit tooling. Submit a drawing for review.
Why Source 1.25mm Board-In Connectors from KONNRA
Dongguan Konnra Electronics Co., Ltd. (brand: KONNRA) was founded in 2004 and is a National High-Tech Enterprise specialising in connector and wiring harness research, development, production, and sales.
Manufacturing depth. A vertically integrated process covering precision mould design and manufacturing, automation design, precision injection moulding, stamping, assembly, and CCD visual inspection. Automation coverage exceeds 95% across production lines.
Testing and validation. A CNAS-accredited laboratory with 45+ sets of precision testing instruments, and CAE analysis — contact nonlinear analysis, material nonlinear analysis, motion simulation, thermal field analysis, and high-frequency analysis — performed in Ansys 2022 R1. Verification data is available on request. For the KR1252 series specifically, the published specification document sets out test conditions and requirements covering contact resistance, insulation resistance, dielectric strength, temperature rise, vibration, mechanical shock, heat resistance, cold resistance, humidity, thermal shock, salt spray, solderability and solder resistance.
Inspection coverage. Full-line intelligent visual CCD inspection covers 95% of production processes, using Mitsubishi and Panasonic PLC control systems with FA25–35mm optical lenses and 5-megapixel cameras. Automotive connector series receive 100% CCD visual inspection.
Quality systems. ISO9001, ISO14001, IATF16949, ISO45001:2018, ISO13485, IPC620, and UL product and operational safety certifications, with automotive-grade series additionally certified to LV214 and US CAR-2. The KR1252 housing and terminal pages list UL file E482542.
Capacity and delivery. Production bases in Dongguan Wangniudun (30,000 m², 350+ employees), Dongguan Changan (10,000 m², 150+ employees), and Hunan Daoxian (2,600 m², 100+ employees), with regional offices in Beijing, Chongqing, Hunan, Shanghai, and Kunshan. Key materials are prestocked, and complete connector set samples can be delivered within 45 days. KONNRA reported 2025 sales of RMB 310 million, with connectors at 60% and wiring harnesses at 40% of the product mix, and has served global cooperative clients including BYD, Volkswagen, and DJI.
Custom and joint R&D. Where a standard part does not fit — a non-standard harness length, a transition to another 1.25mm interface, or a specific plating requirement — KONNRA supports customer joint R&D customisation.
How to Identify Whether Your Connector Is a 1.25mm Board-In Part
If you are holding a connector and a drawing you cannot match, work through these in order:
- Count the parts in the connection. A board-in interface has a housing and crimped wire terminals, and no board header. If there is a separate pin block soldered to the PCB that the housing pushes onto, you have a wire-to-board part, not a board-in part.
- Measure the pitch. 1.25mm points at the Molex 51022 board-in family, or at PicoBlade, CLIK-Mate or PanelMate. It does not distinguish between them.
- Check the housing orientation. Molex documents the 51022 housing as vertical and the 50061 terminal as vertical, so the wire exits perpendicular to the board.
- Count the positions. Molex’s 51022 catalogue is documented from 2 circuits to 15 circuits. A 16-position 1.25mm housing is outside the documented Molex range.
- Look at the housing material and colour. Molex specifies Polyester in Natural. KONNRA specifies Nylon66 with UL94V-0 in White.
- Check whether there is a latch. Board-in is the branch of the 1.25mm family that is not designed for repeated unmating, so a prominent positive lock points at a different family.
- Read the part number if there is one. 51022 is the Molex board-in housing series; 50061 is the 28–32 AWG board-in male crimp terminal; 50080 is the 26–28 AWG board-in crimp terminal; 797581062 and 797581063 are PicoBlade Board-In Pre-Crimped Leads.
If you are still unsure, photograph the connector next to a ruler, with any part number markings visible, and send it to us. At this pitch the measurement identifies the family; the part number identifies the variant.
Frequently Asked Questions
What is a Molex MX1.25 board-in connector?
“MX1.25” is trade shorthand for the Molex 1.25mm pitch. On the board-in side of Molex’s catalogue it maps to the 51022 Board-in Crimp Housing and its matching male crimp terminals, 50061 for 28–32 AWG and 50080 for 26–28 AWG. Board-in means the crimp housing is the part mounted at the board and there is no separate board header. Molex rates the system at 125V maximum and at 1.0A maximum per contact, with a housing operating temperature range of −40° to +85°C.
Which Molex series is the 1.25mm board-in connector?
Molex’s board-in family page describes board-in connectors as meeting the requirements of a cost-effective, easy-to-assemble connection that does not need to be unmated on at least one end. Within that family, the 1.25mm parts are the 51022 crimp housing and the 50061 and 50080 board-in male crimp terminals. Molex lists the housing as “1.25mm Pitch, Board-In Crimp Housing, Vertical”, with Product Name “Board-in” on both the housing and terminal pages.
What is the difference between Molex board-in and PicoBlade?
Architecture and part numbers. PicoBlade is a wire-to-board and wire-to-wire system: a board-mounted plug assembly such as 53047 or 53048, a receptacle housing such as 51021, and receptacle crimp terminals 50079 and 50058. Board-in has no board header at all — the 51022 housing mounts at the board and the crimped terminals load into it. Both are 1.25mm pitch, and they do not share a housing. KONNRA cross-references them as KR1252 for the board-in branch and KR1250 and KR1251 for the PicoBlade wire-to-board and wire-to-wire branches.
What is the KONNRA equivalent of the Molex 1.25mm board-in connector?
The KONNRA KR1252 series — a 1.25mm pitch, single-row board-in connector documented from 2 to 16 positions, with a housing page naming Molex 51022 as the compatible series and a terminal page naming Molex 50080. KONNRA documents the series at 1A and 125V AC/DC on the product and component pages, with the series specification PDF stating 50V AC/DC as the rated voltage.
Does the KR1252 need a wafer or a board header?
No. The KR1252 specification PDF lists the wafer as None, and the product page offers only a terminal and a housing. That is the defining feature of a board-in connector: the housing is the board-side component, so there is no separate header to place, solder or inventory.
What is the voltage rating of the KR1252 board-in connector?
KONNRA publishes two different figures. The product page states Voltage 125V and the Overview paragraph states “voltage ratings up to 125V AC/DC”, and both component pages state Operating Voltage 125V. The series specification PDF, PS-KR1252-01 clause 4.0, states “Rated Voltage (Max.) 50V AC/DC”. Molex publishes 125V maximum for the 50061 board-in terminal. Resolve the KONNRA figure in writing before releasing a drawing, particularly if the specification PDF is the document your drawing calls out.
What is the current rating of the KR1252?
1A. PS-KR1252-01 states “Rated Current (Max.) 1A (26 AWG)”, and both component pages state 1A. Molex publishes 1.0A maximum per contact for the 50061 terminal with 0.8A at 32 AWG, and adds a current derating table by position count in the 1.25mm system specification — for example 1.0A at 30 AWG in a 15-circuit housing. KONNRA publishes no derating table, so if you are running near 1A in a high-position-count housing, confirm the derated value.
What wire does the KR1252 accept?
PS-KR1252-01 states AWG 26# to 32# with an insulation outside diameter of 1.00mm maximum, and the product page Overview paragraph repeats AWG #26 to #32. Both component pages state AWG 28# to 32#. The product page General Specification table separately states “Insulation O.D 1.25mm”, which matches the pitch and disagrees with the 1.00mm figure used everywhere else. Confirm the applicable range and the jacket limit for your specific terminal part number, because 1.25mm pitch with a 1.00mm jacket leaves very little clearance between adjacent wires.
What is the dielectric withstanding voltage of the KR1252 — and does it match Molex?
Yes, this one matches. PS-KR1252-01 clause 5.3 specifies applying 250V AC for 1 minute between adjacent terminals or between terminal and ground, with a requirement of no breakdown and no flashover, and the product page states Withstanding Voltage 250V AC/minute. Molex specifies 250V AC (rms) for 1 minute as the dielectric strength test for the 1.25mm PicoBlade system. The KONNRA figure is therefore a genuine dielectric test value rather than a copy of the rated voltage — the rated voltage on KONNRA’s pages is 125V, so 250V is not the rating. The only caveat is document provenance: Molex’s board-in product specification is referenced from its part pages but was not retrievable for this guide, so the 250V figure is taken from Molex’s 1.25mm system specification.
What is the operating temperature range?
KONNRA documents −40°C to +105°C on both component pages and in PS-KR1252-01, and its heat-resistance test is run at 105±2°C for 96 hours. Molex documents −40° to +85°C for the 51022 housing. The KONNRA part is claimed over a wider window; note that the claim is tested exactly at 105°C, so there is no published headroom above it.
How many positions does the KR1252 come in?
KONNRA documents 2P to 16P on both the product page and the housing component page. Molex’s 51022 catalogue documents housings from 2 circuits to 15 circuits by part number, from 51022-0200 through 51022-1500. That is a one-position difference; confirm the exact count rather than assuming the ranges match.
What is the KR1252 housing made of, and does it differ from Molex 51022?
Yes, it differs. KONNRA specifies Nylon66 (PA66) with a UL94V-0 flammability rating, colour White, in PS-KR1252-01 clause 3.0 and on the housing component page. Molex specifies Polyester for the 51022 housing, colour Natural. These are different polymers with different moisture uptake and thermal behaviour, and Molex’s 51022 part datasheet reviewed for this guide does not state a flammability rating, so the comparison is not “rated versus unrated” — it is two different materials, one of which carries a published V-0 claim.
Is the terminal plating the same as Molex?
Not exactly. Molex documents Tin plating on the 50061 terminal with a minimum of 0.889µm on the mating area and 0.914µm on the termination area. KONNRA documents Phosphor bronze with “Tin plated over nickel” in PS-KR1252-01 and “Tin over Nickel” in the product page General Specification table, with no thickness for either layer. Tin over nickel is a different construction from tin directly on the base metal, so ask for the thickness of both layers if contact finish is part of your qualification.
Is the Molex 50080 terminal still available?
Molex’s part page for 50080-8000 lists the series as Obsolete, with the replacement instruction “Contact Molex”, and points to 50080-8100 as the loose-packaging alternative. An older distributor snapshot of the same part, dated 2013, still shows the status as Active, so the two sources disagree. If your drawing calls out 50080, treat the second-source exercise as necessary rather than optional. KONNRA’s terminal page lists 50080 as its compatible series while documenting the terminal for AWG 28# to 32#, which is Molex’s 50061 range — worth resolving at the same time.
How do I know whether my connector is board-in or wire-to-board?
Count the parts. Wire-to-board needs a board-mounted header that the wire-side housing mates onto; board-in has no header, and the housing itself is the component at the board. Molex’s description of board-in — that the connection does not need to be unmated on at least one end — also tells you that a board-in part will not have the positive latch and repeated-mating design of a wire-to-board family. If you can unplug both ends of the cable, it is not board-in.
How long does it take to get samples?
KONNRA can deliver complete connector set samples within 45 days. Connector production lead time is typically 2–3 weeks and wiring harness lead time typically 3–4 weeks. On a board-in part, sample harnesses from the same process used in production are the more useful sample, because the crimp is the only compliant joint between the wire and the board.
Start Your Cross-Reference Check
KONNRA supplies the KR1252 series as individual components — housing and crimp terminals — or as complete pre-crimped cable assemblies, and builds adapter and transition harnesses to order.
- Request a quote — KR1252 pricing, MOQ and configuration options for your position count and wire gauge
- Request a sample — complete connector set samples within 45 days
- Request cross-reference verification — confirm KR1252-to-51022 equivalence against your specific part number, including plate thickness, wire range and position count
- Request drawings — series engineering drawing (PDF), product specification PS-KR1252-01 (PDF), and package specification (PDF)
- Request a vendor qualification pack — certificates, test capability summary and quality documentation
- Request adapter harnesses — KR1252 to the PicoBlade 1.25mm wire-to-board interface, or another interface on the far end
- Submit a drawing for review — we will flag any specification mismatch before you commit tooling
Contact KONNRA Electronics
- Phone: (86)-769-85449875
- Email: info@konnra.com
- Address: No.6 Nanchang South Road, Chijiao, Wangniudun, Dongguan, Guangdong, China
- Contact us
➡️ Explore the full 1.25mm pitch range · Board-In connector category · Wire-to-board connector catalogue
Orderable components: KR1252 Housing · KR1252 Terminal
Sources and method. This guide compares two published documentation sets and states the differences rather than smoothing them. Molex board-in figures are taken from Molex’s published part documentation: the 51022 crimp housing description “1.25mm Pitch, Board-In Crimp Housing, Vertical, 2 Circuits, Natural”; its Product Family (Crimp Housings), Series (51022), Application (Signal), Product Name (Board-in), Number of Rows (1), Material – Resin (Polyester), Colour – Resin (Natural), Pitch – Mating Interface (1.25mm), Packaging Type (Bag), Temperature Range – Operating (−40° to +85°C), EU RoHS status (Compliant), REACH SVHC status (Not Contained Per D(2020)9139-DC, 19 Jan 2021), halogen-free status (not low-halogen), and its reference drawings, including Product Specification PS-51022-001 and PS-51022-002-001, Sales Drawing SD-51022-001 and Packaging Specification 510229100-EPK-100; the parts used with it, listed by Molex as Board-in Male Crimp Terminal 50061 and PicoBlade Board-In Pre-Crimped Leads 797581062 and 797581063; and the 51022 circuit counts enumerated from Molex part numbers 51022-0200, 51022-0300, 51022-0400, 51022-0500, 51022-0600, 51022-1000 and 51022-1500. The 50061 terminal figures — description “1.25mm Pitch, Board-in Male Crimp Terminal, Vertical, 28-32 AWG, Reel, for 51022 Housing”, gender Male, material Phosphor Bronze, plating Tin with minimum 0.889µm mating and 0.914µm termination, wire insulation diameter 0.50–1.00mm, wire sizes AWG 28, 30 and 32, current maximum per contact 0.8A and 1.0A, voltage maximum 125V, and Sales Drawing SD-50061-8X00-001 — are taken from Molex’s published part data as distributed by an authorised distributor. The 50080 terminal description “1.25mm Pitch Board-In Crimp Terminal, 26-28 AWG, Reel, for 51022 Housing” and its current status are taken from Molex’s published part information, with the status discrepancy between Molex’s current part page and an older distributor snapshot stated in this guide rather than resolved. The PicoBlade 1.25mm system figures — voltage 125V AC (rms)/DC; rated current 1.0A for AWG 26, 28 and 30 and 0.8A for AWG 32; insulation diameter φ0.5 to φ1.04mm; the current derating table by circuit count; ambient temperature −40°C to +85°C; durability of 30 cycles for tin-plated parts; UL File Number E29179; contact resistance 20mΩ max; insulation resistance 100MΩ min at 500V DC; dielectric strength 250V AC (rms) for 1 minute; and temperature rise of 30°C max — are taken from Molex’s PicoBlade 1.25 wire-to-board product specification document number 510211010-PS, revision B, dated 2021, together with the series numbers 50079, 50058, 51021, 53047 and 53048 listed in that document. The 2-to-15-circuit range and the tin/gold and through-hole/SMT and vertical/right-angle options for the 1.25mm family are taken from Molex’s published PicoBlade family information. The description of board-in as a connection type that does not need to be unmated on at least one end, and the statement about the range of pitch options, mating configurations and circuit sizes, are taken from Molex’s published Board-In Connectors family page. KONNRA KR1252 figures are taken from KONNRA’s published product and component documentation: the main product page for pitch 1.25mm, circuits 2-16pin, current 1A and voltage 125V; the General Specification table for material Nylon66/UL94V-0/Phosphor Bronze, Insulation O.D 1.25mm, Withstanding Voltage 250V AC/minute, temperature range −40°C to +105°C, contact resistance 20mΩ max, insulation resistance 100MΩ min and product plating Tin over Nickel; the Overview paragraph for the AWG #26 to #32 wire range, the 125V AC/DC voltage statement and the application fields; the terminal component page for Category Board In, compatible 50080 Series, operating voltage 125V, current 1A, contact resistance 20mΩ max, insulation resistance 100MΩ min, insulation diameter 1.00mm max, wire size AWG 28# to 32#, operating temperature −40°C to 105°C and UL file E482542; the housing component page for compatible 51022 Series, Number of Rows 1, positions 2P to 16P, colour White, material Nylon66 UL94V-0, and the same electrical and UL entries; and the series specification PS-KR1252-01, edition A1, dated 2022/2/26, for the bill of materials (housing H125201 0101A, terminals T12520PT0101A and T12520PT0102A, wafer None), the material and surface-treatment table (housing PA66 UL94V-0, terminal phosphor bronze tin plated over nickel), rated voltage 50V AC/DC and rated current 1A at 26 AWG, AWG 26# to 32# wire with insulation O.D. 1.00mm max, contact resistance measured by dry circuit at 20mV and 100mA to EIA-364-23C, insulation resistance at 500V DC for 1 minute to EIA-364-21B, dielectric strength at 250V AC for 1 minute to EIA-364-20A, terminal insertion force 0.5kgf max, terminal retention 0.7kgf min, the crimp specification at clause 6.3, temperature rise 30°C max to EIA-364-70B, and the vibration, shock, heat resistance, cold resistance, humidity, thermal shock, salt spray, solderability and solder resistance test schedules. KONNRA publishes two pages for this series carrying identical specification tables; the figures quoted here are taken from the main product page and from the specification and component documents it links to. The KONNRA company information in this guide — founding year 2004, National High-Tech Enterprise status, the Dongguan Wangniudun, Dongguan Changan and Hunan Daoxian production bases with their areas and employee counts, the regional offices, the ISO9001, ISO14001, IATF16949, ISO45001:2018, ISO13485, IPC620 and UL certifications with LV214 and US CAR-2 for automotive-grade series, the CNAS-accredited laboratory with 45+ sets of precision testing instruments, the CAE work in Ansys 2022 R1, CCD inspection coverage, the reported 2025 sales of RMB 310 million with the 60/40 connector-to-harness split, the 45-day sample commitment, the 2–3 week connector and 3–4 week harness lead times, and the named cooperative clients — is taken from KONNRA’s published company and capability information. Where Molex and KONNRA disagree, or where a manufacturer disagrees with itself, the difference is stated in this guide rather than smoothed over. Where a parameter is not stated in the documentation reviewed, the entry reads Not documented. Always confirm final dimensional and electrical requirements against the current manufacturer drawing for your specific part number and position count.
