>QUESTION, PORTIONS OF A SMD PCB DESIGN ARE SWITCHING VOLTAGE CONVERTERS AND 
>RECOMMENDED LAYOUT CALLS FOR MASSIVE COPPER TRACES TO MINIMIZE INDUCTANCE. 
>THE REST OF THE PCB IS NORMAL SMD USING TRACE NARROWING PER RECOMENDATIONS 
>IN IPC-SM-782 SECTION 3.6.2.2 . MY QUESTION IS WETHER THIS WILL CAUSE 
>PROBLEMS DURING REFLOW DUE TO DIFFERING THERMAL MASS ACROSS THE PCB?
>
>
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Michael,
We have several designs in production that use an SO8 under very similar
parameters.
We tie the 4 lands to a large ground plane that is used as a heat sink. We
have not seen any production or reliability problems. We also see SMD
components that draw a large amount of current. They require large traces,
somtimes as large or larger than the land. Same thing here, have not seen
any problems.

PS   Sort of makes you wonder about previous design rules that limit the
size of traces going into SMD lands. 

Regards
Fred Pescitelli
Phoenix Designs
4602 Montauk Rd.
Lilburn, GA   30247
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