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Let me start by saying I made a poor design choice up front, but I'm stuck with it for a while so I'm trying to work around it.

I'm making some custom test chips that feature ~200 nm of gold patterned on top of 500 micron SiO2/Si wafers. Because I assumed that an old procedure of "attach wires by silver epoxy" would be simple and quick, and because I already knew that 500 micron is an unusual thickness, I didn't bother designing my contact pads to be usable with any standard card edge connectors. In the image below, those pads are 2mm wide along a 3mm pitch, and the diced chips are just under 18mm wide. pad layout

Turns out, my wire attachment method is way too damn slow for the number of chips I need to test. Also, I don't want to solder on the pads because the gold is very thin and I don't want to damage any of the other custom materials I'll be depositing. I would like something like a card edge connector but my pattern doesn't fit commercial patterns. Therefore, I'd like to source the internal spring contacts from one and 3D print my own body.

So my question is two part: first, what the heck are the contacts within edge connectors called? My Digikey and Mouser searches are using the wrong keywords, so I can't find those little metal fingers. Second, does anyone have tips on designing custom edge card connectors in this way?

Thanks all!

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  • \$\begingroup\$ perhaps the spring contacts are not sold separately ... have you tried to extract the contacts from an edge connector? \$\endgroup\$
    – jsotola
    Oct 4, 2021 at 23:27
  • \$\begingroup\$ With sufficient quantity, you could probably get a company like Samtec to make custom connectors for you, and skip the 3D printing--which is definitely slower than silver sintering. \$\endgroup\$
    – Hearth
    Oct 4, 2021 at 23:41
  • \$\begingroup\$ @jsotola Actually, I hadn't thought of that. That's a good idea. \$\endgroup\$
    – PoGaMi
    Oct 5, 2021 at 2:13
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    \$\begingroup\$ Don't worry about official edge connector "fingers". Get some pogo pins and build a jig to position them \$\endgroup\$
    – Scott Seidman
    Oct 5, 2021 at 2:29
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    \$\begingroup\$ +1 for pogos, but you can also use 1mm pitch card edge connectors (PCI express), you'll just get more contacts. 3D print a shim/holder to align the chip inside the connector, hold it, and compensate for thickness. \$\endgroup\$
    – bobflux
    Oct 5, 2021 at 22:38

1 Answer 1

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Use a 2-piece board-to-board connector instead. Solder a thru-hole, 3-mm pitch straight connector to the fingers of the PCB card and install the mate on the other end. For example:

(Disclosure: This is my website.)
https://connectorbook.com/identification.html?m=NNK&n=misc_lg_gendered_b2b_conn&s=9159%203mm

https://www.kyocera-avx.com/products/connectors/board-to-board/horizontal-plug-10-9159/

https://www.digikey.com/short/3p5jd7dp

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