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August 1997

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Subject:
From:
"Tully, Marti (AZ15)" <[log in to unmask]>
Reply To:
TechNet Mail Forum.
Date:
Wed, 20 Aug 1997 14:06:07 -0500
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Currently, we design fine pitch pads to be the same width as the lead.
 Occasionally, we find test  failures where both the lead and solder lifts
from the pad.  The solder land prior to this lifting is nicely wetted
although the volume of solder is low.    The low volume solder joints and
this defect are found in one direction on the board.   Our current equipment
does not allow squeegeeing the solder paste at a 45 deg. angle to the board.


It has been suggested that we widen the pad by a couple mils to increase the
volume of the solder possible and this would reduce this type of failure.
 Our #1 production quality issue, however,  is solder bridging  and we do
not want to increase that failure rate.

Because the number of failures after test is at a 'noise' level, we feel a
DOE isn't warrented (yet).  Right now we are doing a 'literature type of
search', looking for data that either supports or refutes the design change
as a method to eliminate the failure.  If you have or know of any
documentation, data, DOE results on this phenomenon that could benefit us,
could you please send the information to me?

Thank you.

Marti Tully, Sr. SQE Honeywell IAC, Phoenix, AZ
Phone  - 602-313-3346
Fax - 602-313-3883
e-mail [log in to unmask]


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