Poh,
If you are putting TSOPs on FR-4 and temperature cycle them you are
going to have problems, no matter how good your joints look.  The
thermal coefficient of expansion mismatch between the part and board is
so great that you will quite often find that the TSOPs will "unzip"
their joints along one entire side!

Bev Christian
Nortel

>----------
>From:  Poh Kong Hui[SMTP:[log in to unmask]]
>Sent:  Monday, November 10, 1997 5:58 PM
>To:    [log in to unmask]
>Subject:       [TN] (TN): ASSY: Good Joint
>
>Hi Technetters,
>
>Could anyone advise, why a good solder joint, failed under temp. cycle. We
>could see there is a pretty good joint, on the 3 sides of the joint (it is
>a TSOP component), and is having sufficient solder coverage, exccpt the toe.
>
>Please someone help to advise..
>
>Thanks you..
>
>
>Poh
>
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