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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