Two-row connector blocks are ubiquitous in small-run and hobbyist PCB designs. Pitches of 0.1" or 2mm are the most common, and there are all sorts of options for board-to-board or board-to-wire connectors. The problem is that pin numbering schemes vary wildly.

Pin numbering schemes I've seen include:

  1. DIP-style counterclockwise: DIP number scheme, taken from Wikipedia
  2. Zig-zag between the two rows: Molex Milligrid numbering scheme
  3. Down one row then the other, but NOT counterclockwise: Molex Micro-fit numbering scheme

In my experience, getting the pin numbers wrong is one of the most common sources of PCB heartbreak. I've done a lot of wire patching to correct 6-pin header layout mistakes... and I've thrown away boards with 70-pin header errors.

My question is: Are there industry standard terms for these (or other) 2-row pin numbering schemes?

I would love to have a short, reliable way to specify these schemes, to allow saying things like "We're using a 14-pin 0.1" header with zig-zag numbering" (or whatever).

Although standardized names with the broadest possible user base are (obviously) better, I realize that there probably isn't one true answer to this question. I'd appreciate answers about how these schemes are named even within smaller subsets of the industry, as long as you're clear about the scope of use (e.g. "At company X we always called the second scheme 'shoelacing'").

  • \$\begingroup\$ xkcd.com/927 \$\endgroup\$ – Lior Bilia Apr 13 '14 at 15:14
  • \$\begingroup\$ I don't know of any standard naming scheme. Sometimes the connector manufacturer doesn't specify a scheme, sometimes it's on the mechanical drawing. It's a dog's breakfast. \$\endgroup\$ – Spehro Pefhany Apr 13 '14 at 20:06
  • \$\begingroup\$ The problem is the pin-out of male connector is mirror image of the female. So if the male connector is 1234 on row 1 and 5678 on row 2, the female would be 4321 on row 1 and 8765 on row 2. Better get a few samples first before doing the land pattern! \$\endgroup\$ – daniel Sep 12 '19 at 9:56

If not the connector is made to a certain specification, say IEC60603-2, there is nothing that says that the manufacturer can't make it anyway he like.

And I have not seen a "default" standard yet.


If You are using/connecting flat/ribbon cable than pin numbering must be zig-zag, because of cable construction. It is also depending on software you are using for develop pcb. In my experience in repairing boards, more or less 1st pin is somehow visibile, other wires mark as for your convenience. Happy HW connecting.


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