Mike,
        Check out "Tombstoning of 0402 and 0201 Components: A study examining
the effects of various Process and Design Parameters on Ultra-Small
Passive Devices" in the NEPCON 99 proceedings.  I would be greatly
interested in your results.  We are conducting our own studies as well.


                        Thanks

Ryan Grant
Process Development Engineer
MCMS
(208) 898-1145
FAX (208) 898-2789
[log in to unmask]

>-----Original Message-----
>From:  McMonagle, Michael R. [SMTP:[log in to unmask]]
>Sent:  Thursday, September 23, 1999 11:59 AM
>To:    [log in to unmask]
>Subject:       [TN] 0402 Land Patterns?
>
>        We are looking at current trends in 0402 land patterns and effects
>on tombstoning. This will result in a DOE incorporating the current
>varieties of existing designs to improve post-reflow quality levels. It will
>also incorporate various surface finishes and stencil modifications. I would
>like feedback on any types of pad layouts (and stencil design) we have not
>yet considered, to allow incorporation into the DOE. We are currently
>looking at following land patterns:
>
>- IPC Standard Layout
>- SMT Plus Layout
>- Siemens Inverted Horseshoe
>- Round Pads (Layout TBD)
>
>        Any help that could be offered (either via TechNet or offlline)
>would be greatly appreciated, including references to studies previously
>conducted....
>
>Mike McMonagle
>PCA Process Engineering Supervisor
>K*Tec Electronics
>1111 Gillingham Lane
>Sugar Land, TX  77478
>(281) 243-5639 Phone
>(281) 243-5539 Fax
>[log in to unmask]
>
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