Hi folks, we are running a new board with 0402 parts on it. It seems that
we are having a tombstone problem as well as a problem with parts not
staying centered on the pads. We are currently using 20 mil square pads on
the board, with 20 mils of spacing between them. Our stencil is 6 mils
thick, laser cut and electro polished. The trapezoidal walled apertures are
slightly reduced, 17 mils square, and centered on the pads. It appears the
chip shooter is placing the parts perfectly. We are using eutectic solder
paste with an OA flux, and reflowing the parts using the recommended profile.

Are there any suggestions any of you might have concerning this size of a
part? Is there a better stencil design, reflow profile, or pad design that
could help us out? I would appreciate any suggestions.

Thanks.

Ed

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