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Reply To: | TechNet Mail Forum. |
Date: | Thu, 9 Oct 1997 21:57:26 -0500 |
Content-Type: | text/plain |
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Address,
This is a two part question:
1. DESIGNERS: Are a majority of Designers designing boards with
the land width and lead width 1 to 1, on anything
less than a .020" pitch?
OR
Do you add 2 to 5 mils width to the land with
respect to the lead width?
2. Manufacturing: Does or has this posed as a problem with
reliability, solder volume on leads or the
achieving the proper solder fillet?
My preference is to have the land 2 to 5 mils wider than the lead to
allow for proper joint solderability. The lead will also be 40/60 or
30/70 centered with respect to the land length. This allows proper
solder forming to the toe and foot. I see a lot of advantages to
adding additional width to the lands where real estate allows. So why
do so many Designers opt for the 1:1 ratio, or am I generalizing?
Please advise.
John Gulley
Inet Inc.
1255 W. 15th
Plano, TX 75075
972-578-3928
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