A Tale of Fresh Eyes, Red Herrings and Dirty Tweezers…
We recently received a call from a contract assembler that was fighting solder balls after reflow. They were getting solder balls on one capacitor and tried to address it with profile changes. Sometimes the problem went away, but it always came back. They were also getting blowholes in the same solder joints from time to time.
First, we tried to identify the root cause for the balling problem remotely. The typical questions when confronted with this issue include:
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On which components are the solder balls occurring?
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Are the defects consistently in the same spot/component, or do their locations vary?
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Was the solder paste fresh and permitted to warm to room...