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Weak joint strength and black residue

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BR

#50581

Weak joint strength and black residue | 8 June, 2007

We have been producing an IMS assembly with SMT dpak's for some time. However, we recently encountered a new problem by chance - the parts can be flicked off with a finger nail. I state by chance because the solder joints are wetted and shiny with little voiding (via x-ray).

The surface finish of components is SN100 and PCB HASL. After part removal the pad looks fine but the component underside is black and appears to be somewhat oily. We are suspecting a component contamination issue and are digging deeper. We have not changed any profiles are placement force settings.

Any thoughts??

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#50582

Weak joint strength and black residue | 8 June, 2007

This is probably an inner plated layer of the component that did not bond well. It may be a component that either has the wrong surface finish for lead-free or can't handle the temperatures. Many times I have seen a similar-looking layer when the layers of terminals come apart during manual rework. But, if the parts come off/apart with minimal force when cold, then there is something wrong with the components.

Good luck,

Jon

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