At 07:04 PM 8/14/97 -0400, you wrote:
>Fellow Technetters:
>
>My company has recently adopted IPC-A-610 as the workmanship standard.
>We build class 2 printed circuit boards.
>This Standard states that blowholes are acceptable, as nonconforming
>process indicators, as long as acceptable wetting is present.
>
>In the past, all blowholes were 'touched up'.  I do not wish to continue
>to rework the bottom side solder joints if it is truly not necessary.
>I do have reservations about saying 'Use As Is' since at least one
>soldering process authority states that blowholes must be reworked.
>
>Does anyone have any quality or reliability data that supports or
>refutes the argument for accepting blowholes as process indicators?
>
>John Ryaby
>Process Engineer
>
>

If your blowholes are caused by plating voids in the barrel, then for every
void or visibly disturbed solder joint you can find, there are other joints
with internal voids.  Since you didn't rework the "hidden" defects, and felt
good about passing this on to your customers, why rework the visible voids??
Blowholes are a classic case where visual inspection fails miserably.
Either accept the boards, blowholes and all, or toss them in the trash.

If you choose to treat the condition as a process indicator, then you may
still choose to toss the worst cases of blowholes into the garbage because
the high incidence rate reduces the field reliability.  The next question
would be how do we assess the reduction in service life for various service
environments.

The better answer is to spend that money on better PWBs.

Steve Mikell
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