Hi Rick,
You did not send any pictures, but the likely scenario is this:
1) the caps are epoxied on the bottom side of the PCB;
2) during reflow soldering, the epoxy under the caps thermally expands,
opening the gaps between the caps and the PWB;
3) the available solder volume fills the larger gap, leaving less solder for
a fillet formation;
4) on cooling, the solder solidifies in the gap;
5) the result is a solder joint showing less fillet--giving the appearance of
insuffucient solder--when in fact you have accomplished 2 good things: a) the
increases solder gap gives you a higher solder joint reliability, and b)
smaller solder fillets do not crack chip capacitors like larger fillets on
occasion do.
Industry documentation is typically of the one-size-fits-all type, and SM-782
falls into this category, not even differentiating pad configurations for
wave and reflow soldering.
RECOMMENDATION: keep your current pad design and educate your
inspectors/customers.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com

In a message dated 09/15/0 16:16:16, [log in to unmask] writes:
>We're experiencing a higher rate of insufficient solder on TC3528 size
>tantalum caps epoxied on the bottom side of the PCB then flow soldered with
>T/H components.  The pads in question are on the low end or possibly a
>little under sized from what SM-782 recommends and I'm wondering if anyone
>using these parts in a similar manner has any recommendations for pad sizing
>to accommodate bottom side flow solder.?

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