Hi Ya Steve,
Yeah, we have a fairly thick (~140 mil) backplane with several leads heat
sinked to the nth degree. Fortunately, our customer had already been
through it once and waived the topside fillet requirement for those babies.
In fact, they said if we did see a good fillet in those locations we fried
the board someplace else. Talk about a process control indicator . . .
Hans
~~~~~~~~~~~~~~~~~~~
Hans M. Hinners
Materials Engineer (Process & Manufacturing)
Warner Robins Air Logistics Center
Avionics Production Division
Manufacturing Branch
380 Second Street, Suite 104
Building: 640, Mail Stop: LYPME
Robins AFB, GA 31098-1638
Voice: (912) 926 - 1970 Fax: (912) 926 - 7164
mailto:[log in to unmask]
http://www.robins.af.mil
-----Original Message-----
From: Stephen R. Gregory [mailto:[log in to unmask]]
Sent: Thursday, August 10, 2000 2:00 PM
To: [log in to unmask]
Subject: [TN] Topside solder fillets after wave...
Hi all!
Been trying to dial a profile in on the wave today with a board that's
fairly
thick, probably around .090", polyimide, all PTH with a fair amount of the
IC's being ceramic. We use a spray fluxer and a RMA flux.
The first boards have been coming off without the preferred topside fillets
at a number of locations. I've been playing with the pre-heat, belt speed,
and even did something that I don't like to do, which was to flux the
topside
of the board.
All to no avail...I still had quite a few places that didn't have topside
fillets, and that is something that doesn't go over well here at all.
I started noticing that the places that didn't have topside fillets were at
the same locations. So I came back to my 'pooter and looked at the gerber
for
the board. What's really weird was that everyplace there's a thermal for a
pin is where I have no topside fillet??? I thought that thermals were
supposed to help prevent that from happening? But it's true, every single
place there is a thermal= no top solder. Has anybody ever seen that before?
-Steve Gregory-
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