TYPE-C-31-M-12 PCB Design Guide: Footprint, Pinout, and Alternatives
USB-C 16-pin USB 2.0 receptacle; generic-class part widely cloned.
The TYPE-C-31-M-12 is the generic 16-pin USB-C receptacle — the connector on a large share of hobby and low-volume boards that charge or enumerate over USB-C. It is a right-angle surface-mount part (8.94 × 7.35 × 3.16 mm) with 16 SMT signal leads plus four through-board shell retention legs, carrying only the USB 2.0 subset of the Type-C pinout: VBUS, GND, D+/D−, CC1/CC2, and SBU. The base part is rated 5 A at 20 V, with 10,000 mating cycles.
A note on names: LCSC catalogs this part under "Korean Hroparts Elec", but that is the distributor's naming — the manufacturer brands itself HRO (krhro.com), and its drawing PDF covers the whole M-12 family, including the M-12A variant in high-conductivity copper rated 6 A. The part is also endlessly cloned, so "TYPE-C-31-M-12" on a marketplace listing describes a class of connector more than a guaranteed footprint.
USB-C failures on boards using this connector are rarely the connector's fault. They are design mistakes around it: missing or shared CC pull-downs, mishandled duplicate USB 2.0 pads, a footprint copied from the wrong clone, or unsoldered retention legs. Each is covered below.
What breaks boards
CC1 and CC2 each need their own 5.1 kΩ pull-down
For a board that takes power, the USB Type-C specification requires a separate Rd pull-down of 5.1 kΩ from CC1 to GND and another from CC2 to GND. A single resistor shared between both CC pins — the mistake that shipped on the Raspberry Pi 4 — breaks orientation and cable detection with e-marked C-to-C cables, and is the number-one reason a board charges from an A-to-C cable but not from C-to-C. Note this is a board design rule from the USB-C spec, not a parameter on the connector drawing.
The 16-pin variant is USB 2.0 only — tie the duplicated data pads pairwise
This connector has no SuperSpeed pairs; the pin table is GND on A1/B12/A12/B1, VBUS on A4/B9/A9/B4, CC1 on A5, CC2 on B5, and two copies of the USB 2.0 data pair (A6/A7 and B6/B7) so either plug orientation lands on live pads. Tie DP1 to DP2 and DN1 to DN2 with short stubs. If your product needs USB 3.x, this whole connector class is out — you need a 24-pin receptacle.
Verify the footprint against the exact vendor drawing, not the part name
Because the part is generic and widely cloned, pad geometry, mid-mount versus top-mount bodies, and retention-leg holes vary between vendors selling under the same name. The HRO drawing specifies eight 0.30 mm signal pads on 0.5 mm pitch plus four wider 0.60 mm shared VBUS/GND pads, with through-board holes for the four shell legs. Pull the drawing for the connector you will actually buy, check it against your footprint, and keep copper clear of the retention-leg holes.
Solder the shell retention legs — they carry the mechanical load
Insertion force is specified at 5–20 N and removal at 8–20 N, and that load must not be carried by the sixteen 0.3 mm signal joints. The four through-board legs are the mechanical anchor: give them plated holes and solder them. Placement matters too — the drawing references the recommended layout to the PCB edge, so board-edge position tolerance directly affects how fully a cable seats.
Merge the VBUS pads with real copper, and protect the port
VBUS appears on four pins (A4/B9/A9/B4) and GND on four more; merge each group with copper sized for your actual current budget. The connector itself is rated 5 A (6 A for the M-12A variant) — the often-quoted 3 A figure is the USB-C default-current design target for board copper, not this connector's limit. Add ESD protection such as a USBLC6-2SC6 on D+/D−, and consider a PPTC polyfuse on VBUS so a shorted cable doesn't take out the board.
Key specifications
| Parameter | Value | Source |
|---|---|---|
| Pins / variant | 16 pins, USB 2.0 subset only — pin table: A1/B12/A12/B1 GND, A4/B9/A9/B4 VBUS, A5 CC1, B5 CC2, A6 DP1, B6 DP2, A7 DN1, B7 DN2, A8 SBU1, B8 SBU2; no SuperSpeed pairs | TYPE-C-31-M-12 drawing (base M-12 sheet), USB TYPE-C PIN ASSIGNMENTS table |
| VBUS rating | 5 A current rating, 20 V voltage rating (base M-12; the M-12A 'high-conductivity copper' variant is rated 6 A) | TYPE-C-31-M-12 drawing, Note 4-1 Electrical Performance |
| Mounting style | Right-angle (90°) surface-mount receptacle with 4 through-board shell retention legs; mounted at PCB edge ('RECOMMEND P.C.B LAYOUT' is referenced to PCB EDGE) | TYPE-C-31-M-12 drawing, views and recommended PCB layout |
| Pad pitch | 0.5 mm centre-to-centre on the signal pads (recommended layout: 8 pads 0.30 mm wide on 0.5 mm pitch plus 4 wider 0.60 mm shared VBUS/GND pads) | TYPE-C-31-M-12 drawing, RECOMMEND P.C.B LAYOUT (8-0.30, 4-0.60, 0.50/1.50/2.50/3.50 symmetric pad-pair dimensions) |
| Mating cycles / environment | 10,000 cycles durability (insertion force 5–20 N, removal force 8–20 N); operating temperature -30 °C to +85 °C | TYPE-C-31-M-12 drawing, Notes 3-1..3-3 Mechanical Performance and Note 5 Environmental Performance |
Verified against the manufacturer datasheet on 2026-07-09. Confirm the current revision before production use.
Alternatives
- USB4105-GF-A — GCT's connector in the same 16-pin USB 2.0 class, with a properly documented, stable footprint from a brand-name vendor — the upgrade path when clone footprint roulette isn't acceptable.
- 24-pin USB-C receptacles (JST, Amphenol) — full-featured Type-C with SuperSpeed pairs for USB 3.x designs; finer-pitch and harder to solder, often hybrid SMT/through-hole.
- 6-pin power-only USB-C — just VBUS, GND, and CC pins for 5 V charge-only designs (up to 3 A default USB-C current); no data pads at all, and easier to hand-solder.
Common questions
- Why does my USB-C board charge from an A-to-C cable but not C-to-C?
- Almost always the CC resistors. A power-sinking board needs an individual 5.1 kΩ pull-down on CC1 and another on CC2 per the USB-C specification; a shared single resistor breaks detection with e-marked C-to-C cables, so the source never turns on VBUS. A-to-C cables mask the error because the resistor lives in the cable.
- Can the 16-pin USB-C connector do USB 3.0?
- No. The 16-pin variant carries only the USB 2.0 subset — VBUS, GND, CC, SBU, and duplicated D+/D− pads for both plug orientations — with no SuperSpeed pairs. USB 3.x requires a full-featured 24-pin receptacle.
- How much current can the TYPE-C-31-M-12 carry?
- The manufacturer drawing rates the base connector at 5 A and 20 V, and the M-12A high-conductivity-copper variant at 6 A. The commonly quoted 3 A is the USB-C default-current design target for your board copper, not the connector's limit — size the merged VBUS pours for whatever current you actually negotiate.
- Where is the TYPE-C-31-M-12 datasheet?
- The manufacturer is HRO (krhro.com; LCSC lists it as "Korean Hroparts Elec"), and the official drawing PDF covering the M-12, M-12A, M-12B, and M-12C variants is attached to the HRO product page linked above. Because clones abound, verify the drawing matches the exact vendor you buy from.