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August 2000

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Subject:
From:
"Barmuta, Mike" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 28 Aug 2000 10:15:06 -0700
Content-Type:
text/plain
Parts/Attachments:
text/plain (186 lines)
Franklin: I think the point of Alain's question was to see if the flux your
client was using could be part of the problem. Using your HASL flux vs their
wavesolder flux would help point at the possible root cause of the problem.
Since you are not seeing voiding/bubbles with your flux, it could be coming
from their process.

A couple of questions and things to look for:
1. Are the boards you are testing from the same bareboard production lot
that the problem boards are from? Are they from the clients storage or are
they boards you have retained at your facility?
2. Was the client doing the assembly seeing this problem on other/different
boards at the time?
3. Is the problem specific to a certain area of the board or all over it?
4. Is the problem specific to a certain type or style of component?
5. Is it possible to obtain and test a sample of the exact flux that was
used to solder these problem boards ?

Answering these should help to better direct you to the cause.

I have seen similar outgassing problems from contaminated wavesolder flux.
It would volatize in the solder wave causing the same "swiss cheese"
appearance, although not severe as this one. If you look closely at the
pictures, especially pic 2, the outgassing does not look like it is
originating from the hole wall which would be the case if it was strictly
moisture absorption in the board coming out. Although it is difficult at
times to determine origin when looking at a two dimensional finite slice of
a three dimensional object.


regards

Michael Barmuta

Staff Engineer

Fluke   Corp

Everett WA

425-356-6076

-----Original Message-----
From: Franklin D Asbell [mailto:[log in to unmask]]
Sent: Monday, August 28, 2000 9:24 AM
To: [log in to unmask]
Subject: Re: [TN] Bubbles in through holes


We used the same flux we use for our HASL process, which would be the
same used to HASL them originally, a year ago (not to be confused with
the same flux from a year ago)

Thanks,

Franklin

Alain Savard wrote:
>
> Did you use the same flux as your client?
>
> Alain Savard, B.Sc.
> Chemical Process Analyst
> CAE Electronics Ltd.
> e-mail: [log in to unmask]
>
> -----Original Message-----
> From: Franklin D Asbell [mailto:[log in to unmask]]
> Sent: August 28, 2000 11:58 AM
> To: [log in to unmask]
> Subject: Re: [TN] Bubbles in through holes
>
> Contamination either of the bare board itself, or the component leads
> was something we considered. I took one of the bare boards and
> contaminated it with dust, dirt, and oil from outside our wet process
> area and then floated the board in solder...it actually soldered very
> good. In fact, none of the boards we soldered in our lab exhibited the
> condition, only the boards soldered at our customers facility. This
> included populated and bare boards for what it's worth.
>
> Appreciate the comments,
>
> Franklin
>
> Alain Savard wrote:
> >
> > I agree with Brian on this one. We usually require baking on boards more
> > then 6 to 8 months old. The FR-4 will have absorbed sufficient moisture
in
> > the (im)proper storage condition.
> > Also verify for contamination on the components leads.
> >
> > Alain Savard, B.Sc.
> > Chemical Process Analyst
> > CAE Electronics Ltd.
> > e-mail: [log in to unmask]
> >
> > -----Original Message-----
> > From: Brian Ellis [mailto:[log in to unmask]]
> > Sent: August 28, 2000 11:01 AM
> > To: [log in to unmask]
> > Subject: Re: [TN] Bubbles in through holes
> >
> > Franklin
> >
> > Rarely have I seen such an example of blowholing! You should patent your
> > process for
> > reducing the amount of lead in an assembly :-). Your board has simply
> > absorbed a lot of
> > moisture. A prebake will mitigate the problem, but prevention is better
> than
> > cure.
> >
> > Brian
> >
> > Franklin D Asbell wrote:
> >
> > > Help...
> > >
> > > A customer has brought a problem to our attention. The yare
experiencing
> > > 'air bubbles' in through holes after wave soldering.
> > >
> > > The copper plating in the hole is averaging 1.25 mils, we have not
seen
> > > any compromised hole walls, only bubbles, they even extend up and out
of
> > > the hole next to the component leads.
> > >
> > > I have uploaded pictures on our website, any assistance would be
> > > appreciated.
> > >
> > > These boards were fabricated here in Texas 13 months ago, the customer
> > > did not bake the boards prior to processing. Thanks
> > >
> > > You can view these pictures at this link:
> > > http://www.networkcircuits.com/technical.htm
> > >
> > > Franklin D Asbell
> > > Network Circuits, Inc.
> > > Irving, Texas 75061
>
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