Take a look at IPC-7721 (Repair and Modification of Printed boards and electronic Assemblies) numbers 3.3.1 (Hole repair, Epoxy Method) and 3.3.2 (Hole Repair, Transplant Method) for reliable repairs. If you can't get your hands on the spec, here is a link....  http://www.circuittechctr.com/guides/3-3-2.shtml Jeff Ferry owner and operator of Circuit Technology was on the repairability subcommittee for 7721.
 
Eva J
The QA Gal

________________________________

From: TechNet on behalf of Dehoyos, Ramon
Sent: Fri 6/9/2006 2:50 PM
To: [log in to unmask]
Subject: Re: [TN] Reworking PEM nut on PCBA



        You might have to bond it to reinforce it. Another possibility
is to build up the material around the hole and have it redrilled to
original size.
        Ramom
        

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Peter Lee
Sent: Friday, June 09, 2006 1:57 PM
To: [log in to unmask]
Subject: [TN] Reworking PEM nut on PCBA

Does anyone have recommendation on a process to remove self-clinching
PEM nut from the board? An incorrect 4-40 size and 1/4" long nut was
mistakenly installed and needs to be removed and replaced with a similar
but shorter nut.

Would I lose much of the clinching strength by re-using the hole? Is
there any work-around to reinforce the hole to achieve the similar pull
strength as before?

Any suggestion is appreciated.

Rgds,
Peter

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