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Leadless(passives) solder joint criteria

C. Ortner


Leadless(passives) solder joint criteria | 29 September, 2000

We work in a "low" volume high reliability house building mixed tech double sided multi layer CCA's for long lived space applications. Our present problem is inspection questioning every dimple/anomaly on every leadless part(we put passives only thru the convection oven process). They question things that don't appear to be covered in any specification. Once insp questions something it's stopped until the ME's can justify why it is or isn't rejectable. IPC and other older spec's don't even show pictures or discuss some of these issues being brought up. Example:

Shallow striations(stretch marks) caused from the 2nd side solder process. All other aspects of the joints are beautiful. I feel this is a process indicator but not rejectable.

Also, has any one run into tantalum caps(the ones with the holes or belly buttons). They appear to be an acceptable aspect of the part but they can trap moisture and often prove to have poor solderability around the area. How can a high rel house justify using them?

Does anyone know of a comprehensive spec or resource that goes into detail for leadless parts. It feels like every problem needs to be solved with a 6 week+ comprehensive test(who can afford that). Yet these problems are common in the industry. Is there a resource? TKS co

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Re: Leadless(passives) solder joint criteria | 29 September, 2000

It's easy to reject everything is it?

IPC offers excellent training courses for inspectors in interpreting A-610.

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