Hi Phil,
Yep. Most of the time it's either 4 or 6 mil. Once in a while I'll order a
5-mil. I find it interesting that nowdays that what I consider my "thick"
stencils are only 6-mils thick. It doesn't seem like it was that long ago
that my two favorite thicknesses was 8 and 10-mil.
I don't homeplate much at all. Have never really needed to since I've always
used water soluble paste and we clean everything we build. Have I seen
mid-chip solder balls with 5 and 6-mil stencils, you bet. But it's been my
observation that with 4-mil stencils I don't see mid-chip solder balls. I
also asked others here just in case I was going blind, and they said that
they don't see them either...TIFWIW
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Bavaro
Sent: Tuesday, May 01, 2012 3:33 PM
To: [log in to unmask]
Subject: Re: [TN] Homeplates on 4 mil thick stencils?
I only have mild experience with 4 mil stencils.
Steve,
I assume you have used 5 and 6 mils as well. Is it correct to assume that
you never homeplated those designs either?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Tuesday, May 01, 2012 10:47 AM
To: [log in to unmask]
Subject: Re: [TN] Homeplates on 4 mil thick stencils?
Dear Technos,
I see questions towards Steve, does this mean you use 4 mil stencils and
your experience goes against his? Should I take this as 4 mil would create
mid-chip balling without homeplating because you've seen it, or it is rather
technical curiosity?
Thanks,
Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer T |
450.967.7100 ext.244 E | [log in to unmask] W | www.digico.cc
N'imprimer que si nécessaire - Print only if you must
-----Message d'origine-----
De : Phil Bavaro [mailto:[log in to unmask]]
Envoyé : May-01-12 1:28 PM
À : [log in to unmask]
Objet : Re: [TN] Homeplates on 4 mil thick stencils?
Steve,
I would check your wrap around termination capacitors. There are many ways
to skin that cat and I suspect your paste aperture is already less than
1-to-1.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Tuesday, May 01, 2012 7:28 AM
To: [log in to unmask]
Subject: Re: [TN] Homeplates on 4 mil thick stencils?
Hi Richard,
I just looked closely at some product that we were running today that's
using a 4-mil stencil (with no homeplates), and I don't see any mid-chip
solder balls, and I looked at where they would most likely occur if there
were to be any:
http://stevezeva.homestead.com/4-mil_no_homeplate.JPG
I can't say that we NEVER have any, sometimes it happens, like when the
wrong sized part is used on a footprint designed for something else (oh
wait, that never happens!). But overall, usually don't see them when we use
a 4-mil thick stencil.
Steve
-----Original Message-----
From: Stadem, Richard D. [mailto:[log in to unmask]]
Sent: Monday, April 30, 2012 3:56 PM
To: TechNet E-Mail Forum; Steve Gregory
Subject: RE: [TN] Homeplates on 4 mil thick stencils?
Steve,
Somewhat related to the other discussion on cleaning of no-clean:
Do you wash the assemblies after reflow, and is that why you do not see any
mid-chip solder balls?
Do you wash any CCAs that have been processed with a no-clean solder paste
or no-clean wire solder?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Monday, April 30, 2012 2:42 PM
To: [log in to unmask]
Subject: Re: [TN] Homeplates on 4 mil thick stencils?
BTW I forgot to add I don't homeplate anything...
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Monday, April 30, 2012 3:16 PM
To: [log in to unmask]
Subject: Re: [TN] Homeplates on 4 mil thick stencils?
Hi Ioan,
We use 4-mil thick stencils quite often and I don't see mid-chip balling...
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Monday, April 30, 2012 2:54 PM
To: [log in to unmask]
Subject: [TN] Homeplates on 4 mil thick stencils?
Dear Technos,
It is my first 4 mil stencil and I was wondering if mid-chip balling is
still an issue at this thickness (no-clean process). Should I still
homeplate the apertures of passives, as I fear insufficient solder?
Thanks,
Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer T |
450.967.7100 ext.244 E | [log in to unmask] <mailto:[log in to unmask]> W |
www.digico.cc <http://www.digico.cc/>
N'imprimer que si nécessaire - Print only if you must
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