Bottom Termination Parts-Xray Inspection Criteria

First, I would inspect for lack of solder bridges from the center slug to the outside leads. I would then look for evidence that the solder paste has reflowed beneath the component, without leaving too much void percentage.

Typically we allow up to 25% voiding for these parts, in RF applications I have seen a push towards a much lower void percentage.

Controlling the voiding is related to the paste deposition, percentage of coverage of the center pad, and to the pattern by which the paste is deposited on the PCB. For example, a square will leave larger void % than a pattern of dots of the same solder volume.

Shoot for about a 30-35% reduction of solder beneath the component.

'hege

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