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October 2007

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Subject:
From:
"Green, Mike" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Green, Mike
Date:
Wed, 10 Oct 2007 12:07:29 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (90 lines)
It is a lug.  Our lugs have eyes for attaching jumper wires that can be
soldered to plated through holes in boards.  If you try to attach a
fastener to a plated through hole, the fastening method (torque, swage,
etc.,) will apply enough compressive force crack the hole.  The .001
inch of copper plating thickness in the hole is not very sturdy when
compared to such huge forces as finger tight. (Multiply torque by a
thousand to determine force per square inch.)  If your reliability is
such that a cracked hole will satisfy your needs, then it might be worth
is risk.

Mike Green
Electronic Packaging Design
LMCO-Sunnyvale
408-743-1635

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bloomquist, Ken
Sent: Friday, September 21, 2007 10:14 AM
To: [log in to unmask]
Subject: Re: [TN] Screwing to a PWB

I've gotten some great comments on attaching lugs to our CCA. One thing
I was surprised about was that no one seemed to have a problem with
screwing something to a multilayer plated through hole. For some reason
I always thought that was a bad practice. I always thought that you were
only supposed to screw to a non supported hole. Maybe I was wrong.

Phil mentioned below to roll swage and then solder to a pad. Again I
thought that was forbidden on a PTH. J-Std-001 6.2.5 says that you can't
do that. 

Comments?

Thanks,

KennyB


-----Original Message-----
From: Phil Nutting [mailto:[log in to unmask]] 
Sent: Friday, September 21, 2007 5:09 AM
To: TechNet E-Mail Forum; Bloomquist, Ken
Subject: RE: [TN] Screwing to a PWB

Kenny,

This is a common problem for us.  Several solution are as follows.

1. Swage in threaded standoffs by RAF, Lyn-tron and Promptus can be roll
formed into the board and then soldered.
2. For real heavy leads (6 to 00 AWG) PEM press in studs designed for
grounding applications work well.  We have some we torque to 55 in*Lbs.
We do solder these to the board.
3. For anti-vibration we use Nylon patch screws/bolts or nuts.  Check
out ND Industries, Long-Loc or Nylok.  There are several other
competitive products.
4. For connections screwed directly to the boards we use Keystone 6-32
or 10-32 Insert Terminals (Keystone p/n 1284 & 1293).  We have tried
some of the PEM pcb fasteners, but they were always problematic for
assembly folks.

Phil

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