Steve,
I think the answer is, "it depends". We have a rigid-flex board that is .093" thick and had issues with press fit nuts, but ended up increasing the hole size a tiny bit to lessen the force required to press the nuts in. We had a supplier using a 5 ton hydraulic baring press to do the pressing and they promptly delaminated the boards. (That was not needed to press them either, you could do it with a pair of pliers almost.) Ouch!
Anyway, I have done .031" boards in the past and used Pem nuts in them just fine. Just take note that they recommend different hole sizes for PCB versus sheet metal, etc. That said, in our case, increasing the hole size slightly, prevented the board from getting damaged during the press operation. The key to watch is the press section of the nut/spacer, and that it's not any longer than the board thickness.
I've done both plated and non-plated holes and had good results in both cases so plating wasn't an issue in my cases at least. I would suggest that if you do plate the holes, don't use HASL for the finish, that will cause issues sometimes. In all cases too, the compression mode was to pull the nut into the PCB and not push it away/out. In the case of the .093" board, the press was just enough to hold the nut in during assembly and a few on off cycles so we've not had any issues with the larger hole size. Don't know if this helps or not, but...
Later...
Scott Decker | Senior Engineer, PCB Design Services CID+ | Electronic Systems Center
COLLINS AEROSPACE
3445 S. 5th Street, Suite 170, Phoenix, AZ 85040 U.S.A.
Tel: 602 308 5957 FAX: 602 243 2347
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Thursday, August 22, 2019 1:05 PM
To: [log in to unmask]
Subject: [External] [TN] Minimum PCB thickness for press-fit technology?
Hi all!
I thought I'd throw the question out there while I'm google-ing for it, is there a minimum PCB thickness that you would want to use press-fit technology? I'm thinking it's .062", I think I read that somewhere, now I'm trying to find it. But a .031" thick PCB seems too thin. Thoughts?
Steve
--
Steve Gregory
Kimco Design and Manufacturing
Process Engineer
(208) 322-0500 Ext. -3133
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