What is the Molex MX1.2 connector, and what should I check before cross-referencing it?

Molex does not sell a product called "MX1.2."

The string is trade shorthand built from the 1.20mm pitch, and it maps to the Molex Pico-EZmate 1.20mm connector system. That much is harmless. What causes trouble is the two numbers hiding inside the everyday name of this connector: a 0.05mm pitch difference that separates it from a different Molex family, and a 0.1mm height difference that changes at the sixth circuit position.

I work on connector and harness programmes at KONNRA, which builds a documented cross-reference to this system (the KR1200). Here is what actually matters about the part.

What the Pico-EZmate 1.20mm system is

A 1.20mm-pitch, single-row, vertical-mating wire-to-board connector, designed for space-constrained devices where board height, not board area, is the binding constraint.

• Circuits: 2 to 6
• Mated height: 1.55mm for 2–5 circuit versions, 1.65mm for the 6-circuit version
• Current rating: 1.5A maximum per contact
• Voltage rating: 50V AC (RMS)/DC maximum
• Applicable wire: AWG #28 to #30, insulation 0.60 to 0.70mm
• Contact resistance: 20mΩ max · Insulation resistance: 100MΩ min
• Dielectric withstanding voltage: 500V AC
• Operating temperature: −40°C to +105°C
• Plating: gold, 0.100µm minimum on the mating and termination areas
• Housing: LCP, UL94V-0, black
• Mating: vertical, onto an open-top header with open space for pick-and-place
• Retention: friction lock with an audible click, plus a polarizing key
• Molex part families: 78172 receptacle housing · 78171 header · 36920 off-the-shelf cable assemblies
• KONNRA equivalent: KR1200

The naming trap: PicoBlade is not Pico-EZmate

These are two different Molex families with almost identical names, both used in compact electronics, and they do not mate:

• PicoBlade — 1.25mm pitch, wire-to-board and wire-to-wire, horizontal or vertical mating, two-point contact design. Trade shorthand "MX1.25". KONNRA equivalents: KR1250 (wire-to-board) and KR1251 (wire-to-wire).
• Pico-EZmate — 1.20mm pitch, wire-to-board only, vertical mating, friction lock with an audible click. Trade shorthand "MX1.2". KONNRA equivalent: KR1200.

1.25mm is not 1.20mm. A PicoBlade housing will not mate a Pico-EZmate header, and over a 6-circuit connector that 0.05mm per position compounds across the whole contact field. In my experience this is the single most common error on an MX1.2 enquiry — and because the two part numbers look like neighbours, it usually survives several rounds of quoting before anyone notices.

A rule worth adopting: on any Molex sub-2mm connector, confirm the pitch on the drawing before you cross-reference anything. Molex alone runs Pico-EZmate at 1.00mm, 1.20mm and 1.80mm, PicoBlade at 1.25mm, and Pico-Clasp at 1.00mm — and none of them mate.

Mated height: 1.55mm or 1.65mm — and it changes at six circuits

Molex specifies two mated heights for the same system:

• 2 to 5 circuits → 1.55mm
• 6 circuits → 1.65mm

This is the number that usually decides whether the design works, and the one most often missed. The difference is 0.1mm, and 0.1mm is the difference between a 6-circuit version fitting under an enclosure rib and not fitting. If your clearance budget was calculated on a 2-circuit prototype at 1.55mm, your production build in 6 circuits is 1.65mm — and the budget is already spent.

And KONNRA does not publish a mated height for the KR1200. The product page describes an "ultra-low profile docking height" without giving a figure. Given that height is the whole reason most designers pick this connector, that is the first thing to confirm in writing, for your specific circuit count — not for the family in general.

The rating, and the counterintuitive part: more current means a smaller pitch

The Pico-EZmate 1.20mm is rated 1.5A per contact at 50V. The 1.5A figure is established with AWG #28 wire. AWG #30 is inside the system's applicable range but is not the gauge that rating was established with — so if your harness uses #30 and you are running close to the limit, confirm the figure for your gauge rather than carrying the family number across.

The part that surprises people: if you need more than 1.5A, Molex's answer is a different pitch, not a bigger version of this one.

• Pico-EZmate Plus — 1.00mm pitch, 2.8A, AWG #28 and #30, mated height 1.20mm
• Pico-EZmate HC — 1.80mm pitch, 5.0A, AWG #22 and #24, dual locking system

So the family moves both ways: up in current means going down in pitch (Plus) or up in pitch (HC). There is no 1.20mm Pico-EZmate rated above 1.5A. And KONNRA's published KR1200 covers only the standard 1.20mm path — no Plus or HC equivalent is documented against it, so a 2.8A or 5.0A requirement is a different conversation rather than a different KR1200 variant.

Cross-referencing to the KONNRA KR1200 — and the gaps worth knowing

The KR1200 is documented at component level — a wafer, a housing and a crimp terminal — each with its own page and drawing. Where the two documents agree is worth stating: the pitch, the 1.5A current rating, the 50V rating, the 20mΩ maximum contact resistance, the 100MΩ minimum insulation resistance, the −40°C to +105°C operating range, and the open-top geometry with pick-and-place clearance.

Where they differ, in the order the differences bite:

• The dielectric withstanding voltage disagrees by a factor of ten — and KONNRA's own page contradicts itself. Molex specifies 500V AC dielectric withstanding voltage. The KONNRA specification table states 50V AC / minute — which is exactly the connector's rated voltage, the pattern you get when a withstanding-voltage row has been filled with the rating instead of the test value. KONNRA's Overview text on the same page says the connector "can also withstand voltage spikes of up to 500VAC/minute". So one page carries two different figures for one parameter, and the row an engineer copies into a drawing is the one that disagrees with Molex. If your qualification calls for a dielectric test, resolve it in writing.
• Circuit count — 2 to 6 versus 2~7P. Molex documents 2–6; KONNRA documents 2 to 7 positions. One position wider. Either KONNRA tooling covers a 7-position housing Molex does not, or the range means something else — confirm the exact count.
• Plating thickness is specified by Molex and not by KONNRA. Molex: gold at 0.100µm minimum on mating and termination. KONNRA: gold flash over nickel, no thickness. Gold flash is a thin deposit rather than a full gold plating, and the two are not equivalent in thickness or long-term contact stability. Ask for microns.
• Mated height is published by Molex and not by KONNRA — covered above, and it is the highest-value missing number on this part.
• Wire insulation diameter is specified differently. Molex: 0.60 to 0.70mm. KONNRA: 0.75mm max. Molex-compliant cable sits inside the KONNRA window, but heavier insulation that would fail Molex's spec still passes KONNRA's 0.75mm figure. Pin the dimension to your drawing.
• Retention is described differently. Molex specifies a friction lock between housing and header with an audible click. KONNRA's documentation describes the polarizing key and open-top socket head but does not state the friction lock or the click. On a vertical-mating connector with no separate latch, the friction lock is the entire retention budget — so confirm it.
• Header geometry. The standard 1.20mm Pico-EZmate mates vertically onto an open-top header; Molex also lists right-angle single-row headers in its 1.20mm range (series 202656). KONNRA documents its KR1200 wafer as a right-angle SMT type. Confirm which geometry your part number corresponds to — the footprint and the mating direction both change.
• Mating durability is published by neither side. Molex's feature list claims "secure contact for multiple cycles" but gives no cycle count, and KONNRA gives none either. If the connector will be re-mated in service, ask for a figure.
• Stock versus build-to-order. Molex sells off-the-shelf assemblies in the 36920 series — 50, 100, 150 and 600mm, in 2, 4, 5 and 6 circuits. KONNRA builds to order. If you need a stock cable tomorrow, that difference matters as much as any electrical parameter.
• Crimp tooling. Molex publishes its own tooling for this system; KONNRA does not document tooling against the KR1200 terminal. If you crimp in-house, ask which applicator and press the terminal is validated against — on a 1.2mm pitch that one question avoids most of the rework.

What to send for a cross-reference check

1. The original Molex part number if you have it — a housing such as 781720003, a header from the 78171 series, or an assembly such as 369200600
2. Circuit count — Molex documents 2 to 6
3. Header geometry — vertical (the standard open-top mating) or right-angle; this decides the footprint
4. Connector only, or a finished harness — and if a harness, the length and the far-end termination
5. Wire gauge and insulation outside diameter — Molex specifies AWG #28–#30 with insulation of 0.60–0.70mm, so the insulation diameter is not optional information on this series
6. Your load current, not just the connector rating — above 1.5A the answer may be a different series rather than a KR1200 variant
7. Application and annual volume
8. A drawing or photo, if the part number is unreadable

With those, four things get confirmed against Molex's own documentation: the circuit count, the header geometry, the mated height for that circuit count, and the plating thickness you need. Those four are where an MX1.2 cross-reference most often goes wrong.

A quick way to check whether you are holding a Pico-EZmate

Measure the pitch: 1.20mm points at Pico-EZmate or JST ACH; 1.25mm at PicoBlade; 1.00mm at Pico-EZmate Plus, Pico-Clasp or JST SH. Then measure the mated height from the PCB: 1.55mm indicates a 2–5 circuit version, 1.65mm the 6-circuit one. Confirm it mates vertically onto an open-top header, and listen for the click. If there is no click and no friction feel, check the series. Part numbers help too: 78172 is the receptacle housing series, 78171 the header series, 36920 the off-the-shelf assembly series.

Full technical write-up: Molex MX1.2 Connector Complete Guide

Disclosure: I work with KONNRA, which manufactures the KR1200 cross-reference. The Molex Pico-EZmate figures above are taken from Molex's own published 1.20mm system documentation; the KONNRA figures are from our published KR1200 documentation. Where the two disagree — or where one source contradicts itself — I have flagged the difference rather than averaged it.

https://konnra.com/molex-mx1-2-connector-complete-guide/
Dongguan Konnra Electronics Co., Ltd