November 5, 2021

Design PCBA for cleaning

Electronic assemblies has changed dramatically in the past 15 years. Decreased chip size, introduction of bottom terminated components and implementation of heterogen integration make cleaning more challenging than in the past.

It is necessary to set rules for components configuration, sort-out some components which have not optimal design of package and be familiar with challenges, which may cause violation of that rules.

For more information on this topic go to page Reliability and download an article Design for cleaning

1: Gap under component

Proper PCB should have the pad and solder mask in the same level. Solder thickness -50-60% of printed solder paste. May vary upon the package weight!

Too thick solder mask – zero thickness of gap.  Not cleanable!

Reverse chip geometry + lone under chip – challenge for cleaning!

Lines under chip – challenge for cleaning.

2: Components with tricky gap

Multilayer ceramic chips have convex bottom – gap seem to be higher than it is.

MELFS are heavy – it press the solder – can easy touch solder mask with body!

Some types of SOD with leads in the body bottom level are not stable – tilting shrinks the gap!
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