Do you have any comments to my questions about what sized holes I can
expect to always be filled for any wave soldering process? How about
the parameters that relate to the maximum size hole filling?
Thanks,
Carl
-----Original Message-----
From: Stadem, Richard D. [mailto:[log in to unmask]]
Sent: Tuesday, January 24, 2012 11:48 AM
To: TechNet E-Mail Forum; Carl VanWormer
Subject: RE: Wave solder - filling of "empty" holes
If the CCA goes through any type of AOI post reflow, then have those
holes added to the inspection. Almost any AOI machine can detect any
unfilled holes.
Also, where is the requirement for the holes to be filled or checked in
your process documentation? Is there an operation where the operator is
told to verify holes are filled, and touchup if not? If they
work/inspect off of the assembly print, can a print note be added?
Somewhere there needs to be a documented requirement that the holes be
filled. Talking to a wave solder operator and trying to get him/her to
"remember" this requirement is futile. They are busy remembering what
they did last Friday night. Find a means to poka-yoke the process so the
holes are always filled.
OR, if there is no other requirement to have any solder in those holes,
leave the solder out of the holes and make a test fixture consisting of
a 2x5 bed of solid nails embedded in a non-conductive material. Just
plug it in when you test each board. The metal pins will seal each hole
and provide electrical contact to the barrels, without shorting the
barrels together. To more easily envision this, suppose you took a
plastic table with ten metal legs, turned it upside down, and plugged it
into the connector holes....except don't use plastic, use Durostone CAS
716, which is dissipative.
If you go that route, you just need to add the masking of the holes to
the process so NO solder is added. A piece of Kapton tape will work, or
peelable/soluble masking.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carl VanWormer
Sent: Tuesday, January 24, 2012 1:01 PM
To: [log in to unmask]
Subject: [TN] Wave solder - filling of "empty" holes
We have a PCB assembly with a 2x5 pin "engineering" header that is not
populated on our production boards. The normal results of our CM's wave
solder process yields boards with the 10 holes (.040" dia.) filled with
solder. Our pointed spring-probe test fixture hits the centers of these
solder-filled holes, and all is good with the world . . .
Occasionally, we have some boards that do not have all of the holes
filled (I can provide a picture if it helps the discussion). The test
fixture spring-probes may penetrate into the unfilled holes, making only
intermittent contact with the hole-walls. My final solution may be to
obtain spring-probes with wider tips to bridge the hole, making contact
with the annular ring, but I'd like to get opinions from the group as to
my expectations of hole-filling in the wave solder process.
I'm sure that 10mil holes will always fill, and 1000mil holes, will
never fill. What expectations should I have with my 40mil holes (in my
62 mil thick PCB)? If the consensus is that the holes should fill, what
suggestions can I give to my CM to facilitate my desired hole filling?
Thanks,
Carl
Carl Van Wormer, P.E., AE7GD
Senior Hardware Engineer
Cipher Systems
1800 NW 169th Place, Suite B-100
Beaverton, OR 97006
Cipher Systems (503) 617-7447 x 5163
Direct Line (503) 425-5163
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