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October 1997

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Subject:
Lengthening stencil opennings under fine pitch parts.
From:
Charles Barker <[log in to unmask]>
Reply To:
TechNet Mail Forum.
Date:
Thu, 16 Oct 1997 14:56:03 -0500
Content-Type:
text/plain
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text/plain (35 lines) 
Charles Barker@IO-US
10/16/97 02:56 PM

The problem that stirred all this up is insufficient solder on the leads of
fine pitch devices.

I have been asked to gathter information on lengthening the footprint of
the openning in some of our stencil in the direction up under the
components to provide more solder on the heels of the leads. Does any one
have any design guidelines and/or experience with this technique? Some
questions I have are:

1. What is the determining factor(s) to cause the need for this.
2. How far should the openning be extended past the end of the pad?
3. Have you seen additional solder balling as a result of using this
technique?
4. Have you experienced additional bridging?
5. Any other special considerations or challenges with this technique?

TIA

Charlie B.

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