Solder beads on small caps and res.

We've used both effectively to resolve this issue. Check with your stencil manufacturer. Often, they can give you a very good starting place on issues like this since they see everyone's designs.

John S.

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I have used a 10% area reduction with home plates on 6 mil stencils with good success. If you're using 5 mil stencils you might go with 0 or 5% reduction.

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Look here: http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Message_ID=45733

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I would be glad to help you eliminate the solder balling and beading that you are seeing. As this is a fairly common defect, I would like to forward you an Application Note that we have developed that explains the cause and possible solutions.

Most commonly, slowing the ramp rate in your reflow profile to ~1 degree C per second is a effective way to stop mid-chip balling. I would try this before spending the resources on a new stencil.

Feel free to contact me offline. My information is below.

Sincerely,

Mario Scalzo, CSMTPE, Dartmouth 6 Sigma Green Belt Technical Support Engineer - Indium Corporation mscalzo@indium.com / 1-800-4-indium

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Contact Steve Yen @714-636-6211 or incoming@usastencils.com He'll be happy to help to with that. Good luck !

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