M.2 Connector & Key Types: A, B, M, E Key Sockets

An M.2 socket is chosen by key, then stack height, then the module length the board's standoff allows. The KINGCONN M.2 series lists 0.50mm pitch, 67-contact card-edge sockets in M key and B key at 3.2mm, 4.0mm and 4.2mm stack heights rated 60 cycles; the Mini PCI series keeps 6.7mm and 6.8mm sockets for installed platforms.

Stack height picks the part

Stack height	Key available	What it suits
3.2 mm	M key and B key	single-sided modules, wireless cards
4.0 mm	M key	typical NVMe SSDs
4.2 mm	M key (Gen4)	double-sided SSDs, parts underneath, airflow
6.7 / 6.8 mm	Mini PCI Express	installed industrial PC and gateway platforms

Stack height is the gap between the board and the underside of the module once mated; it has to clear whatever sits under the module. Fix it from the mechanical stack, because the socket is what sets the module's distance from the board. For the key and size tables see M.2 key types.

Legacy platforms: Mini PCI is still in the catalog

Industrial PCs and gateways designed around Mini PCI often ship for a decade or more. KINGCONN lists 6.7mm and 6.8mm Mini PCI sockets for that continuity need. If your original socket source is discontinued, send the part number or drawing and we evaluate supply from existing tooling.

Durability class

A module socket is designed for assembly plus occasional service — catalog M.2 models are rated 60 insertion cycles, which matches "installed once, rarely re-seated". If your application needs repeated insertion, say so in the RFQ.

KINGCONN M.2 and Mini PCI sockets

7NGFF-F0-0302NGFF 67PIN M KEY H:3.2mm

7NGFF-F0-0402NGFF M KEY H:4.0mm

7NGFF-F0-0428NGFF M KEY H:4.2mm GEN4

7NGFF-F0-0305NGFF 67PIN B KEY H:3.2mm

7NGFF-F0-0020-XNGFF 2.0H

7MPCI-F0-0670MINI PCI EXPRESS H:6.7mm

7MPCI-F0-0680MINI PCI EXPRESS H:6.8mm

7MPCI-F0-1012 & 7MPCI-F0-1013mini PCI EXPRESS CONNECTOR H=5.6mm

7MPCI-F0-1014 & 7MPCI-F0-1015MINI PCI EXPRESS CONNECTOR H=4.00mm

M.2 (NGFF) sockets in M key and B key at 3.2, 4.0 and 4.2mm stack heights, and Mini PCI Express sockets at 6.7 and 6.8mm.

Part number	Height (mm)	Pitch (mm)	Drawing
7NGFF-F0-0302	3.2	0.50	7NGFF-F0-0302
7NGFF-F0-0305	3.2	0.50	7NGFF-F0-0305
7NGFF-F0-0402	4.0	0.50	7NGFF-F0-0402
7NGFF-F0-0428	4.2	0.50	7NGFF-F0-0428
7MPCI-F0-0670	6.7		7MPCI-F0-0670
7MPCI-F0-0680	6.8		7MPCI-F0-0680

Materials and RFQ

Housings are LCP rated UL94V-0; contacts are phosphor bronze or copper alloy, with stainless fittings on some models. RoHS compliant, and every published value carries its source drawing number. Send the module type, stack height and quantity to service@kingconn.com.tw.

FAQ

How do I select an M.2 socket?

3 steps: let the module key choose the socket key (KINGCONN offers M key and B key), let component clearance choose the stack height (3.2, 4.0, 4.2mm), and let the standoff position choose which module lengths fit. The socket itself is 0.50mm pitch with 67 contacts and is the same for every length.

Is 60 mating cycles too few for an M.2 socket?

No. A module socket is installed once and serviced rarely, and 60 cycles matches that use. If your application really does re-seat modules often — swappable modules in test equipment, for example — say so in the RFQ and we will suggest a suitable family.

Are Mini PCI sockets still in production?

Yes. Industrial PCs and gateways designed around Mini PCI often ship for a decade or more, and KINGCONN lists 6.7mm and 6.8mm Mini PCI sockets for exactly that continuity need. If your original source is discontinued, send the part number or drawing.

Are M.2 and Mini PCIe interchangeable?

No. Pin count, key and footprint all differ: Mini PCIe is a 52-pin card edge, M.2 is 75 positions (67 contacts when keyed) at 0.50mm pitch. Industrial boards often keep both sockets because the supply life of older modules outlasts the adoption of the new format.

What is the difference between a B-key and an M-key socket?

The rib position, matching the notch on the module edge. An M-key socket accepts M-key and B+M-key modules (PCIe ×4 or SATA, mostly NVMe SSDs); a B-key socket accepts B-key and B+M-key (PCIe ×2, SATA, WWAN modules). See the M.2 key type guide.