Solder balling under passives

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Hi guys, Problem: Mid chip solder balling. Component... - Sep 19, 2016 by Shriram

Hi Shriram, Are you saying that there is a trace running be... - Sep 19, 2016 by A Very Frazzled Man

Whatever the cause is, will be fixed by applying less paste.... - Sep 19, 2016 by Evtimov

Appreciate your suggestion. NSMD pads are used for this d... - Sep 19, 2016 by Shriram

Shriram

#76363

Solder balling under passives | 19 September, 2016

Hi guys,

Problem: Mid chip solder balling.

Component affected: 0603 caps only

Defect is PCB specific (Meaning only one PCB is affected as the aperture is standard for that component).

As a containment I'll give a home plate design for the component but by standard we don't use home plate designs for 0603.

I'm seeing mid chip solder ball only at the location where there is a trace beneath the mask.

Any advice or suggestion for this peculiar case?

Thanks

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A Very Frazzled Man

#76364

Solder balling under passives | 19 September, 2016

Hi Shriram, Are you saying that there is a trace running between the pads for this 0603 capacitor? If so, this design may be causing a gasketing issue between the stencil and the PCB. The uneven height prevents the stencil from sitting flat on the PCB. This unevenness will cause a little more paste to leech out between the stencil and the PCB with the end result being mid-chip solder balls. You are correct to try a home plate aperture as a prevention. It's a cheaper alternative to redesigning the PCB.

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Evtimov

#76366

Solder balling under passives | 19 September, 2016

Whatever the cause is, will be fixed by applying less paste. So Homeplate it is.

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Shriram

#76369

Solder balling under passives | 19 September, 2016

Appreciate your suggestion.

NSMD pads are used for this design, the anomalies we found are

1. the trace running between pads has a lesser solder mask height compared the other area of the pads.