This request is not for Soldermask defined pads.

The Request is for diamond or a tear drop shaped
copper land patterns for the BGA pins. Just curious if
anyone out there had seen this.

Thanks,
dave


Werner Engelmaier wrote:

>Hi Tom,
>The problem with SMD-SJs [solder-mask-defined] is that the SJ geometry
>results in a stress concentration where it is shaped by the solder mask--it has
>nothing to do with bonding area or overall strain distribution.
>
>Regards,
>Werner Engelmaier
>Engelmaier Associates, L.C.
>Electronic Packaging, Interconnection and Reliability Consulting
>7 Jasmine Run
>Ormond Beach, FL 32174 USA
>Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904
>E-mail: [log in to unmask], Website: www.engelmaier.com
>
>
>

David Seymour wrote:

>To All,
>
>
>
>I just had an assy house recommend a diamond shape
>
>or tear drop shape for a BGA land pattern to allow for better
>
>optical inspection related to reflow and solder opens detection.
>
>
>
>Has anyone come across a white paper or reliability study
>
>for or against alternative pad shapes for BGAs?
>
>
>
>dave
>
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--
Dave Seymour, CID+
Catapult Communications Inc.
800 Perimeter Park Dr, Suite A
Morrisville, NC 27560

Direct: (919)653-4249
Main: (919)653-4180
Fax: (919)653-4297

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