You need to check out IPC-SM-782 Surface Mount Design and Land Pattern
Standard. It contains all of the information you are asking for.

> ----------
> From:         Kicha / Krishna
> Sent:         Tuesday, February 24, 1998 9:44 AM
> To:   [log in to unmask]
> Subject:      [TN] SM Lead dimension specification
>
> TechNetters:
>    Hi everyone. I appreciate any help with these following questions.
>
> 1. Where can I find specifications for standard surface mount gull
> wing
> lead dimensions, such as lead width, the length of the flat portion of
> the lead that rests on wet paste for say, 50 mil pitch components ?
>
> 2. Are there specifications for board pad dimensions to match the
> component lead dimensions ? If yes, where can I find them ?
>
> 3. Are the specifications dependent on which side the components are
> mounted (top side / bottom side) to account for the extra care needed
> with regard to surface tension to hold the components on the bottom
> side
> during second reflow.
>
> Thanks for your time
>
> Regards
> Krishna Kalyan
>
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