-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Matt Cirineo
Sent: Wednesday, November 03, 1999 5:28 PM
To: [log in to unmask]
Subject: [TN] Cutting through an inner trace
Other than drilling, has anyone used an alternative method of cutting
through an inner layer trace? I'm thinking of methods such as laser, water
cutting,...
Your comments and suggestions would be greatly appreciated.
Matthew Cirineo
Operations Engineering
Primex Aerospace Company
phone: 425-885-5010 x4855
fax: 425-895-4310
************************************
Matthew,
Back when Unisys was called Borroughs and I was a Sr. Mfg. Engr. , we established a very
workable process for "excavating" inner layers using "microabrasives". Essentially a sand
blaster scaled down to handle fine abrasives like sodium bicarbonate, crushed walnut shells,
alum, etc.at about 5 micron particle size with orifice ID. in the neighborhood of .005". An
enclosure with interior lighting and long focal length microscope was utilized as well. We were
able to literrally "tunnel" under an internal trace to get to a subsequent layer, remove the
short (or cut the connection) then clean and backfill with epoxy. Takes a bit of patience, a
good hand, and selecting the right abrasive for the material being removed. Certain abrasives
tend to remove the epoxy and have lesser effect on the copper, while others effect the copper
more than epoxy. You might want to spend a little time experimenting before you go work on one
of those "mega-buck" boards live!
There are a few manufacturers of such equipment, one is White Industries (if they're still
around). I'd be glad to chat with you on voice if you like. Please feel free to give me a call.
Regards,
Ed Popielarski
QTA Machine
10 McLaren, Ste. D
Irvine, Ca. 92618
949-581-6601 Ph
949-581-2448 Fx
http://www.qta.net
Ask about our BGA Reballing system!
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