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Solder joint strength



Solder joint strength | 6 October, 2004

Dear all,

Recently our customer complaint that some components being came off from the pcba after dropping test.But the curious is, the leads show visible solder fillet covering more than 75% of termination area on pad, which is acceptable as per IPC-A-610 C. Can anyone provide us the information on what should the shear strength on these component so we can conduct the pull/push test, or some alternative solutions ? The info for the lead terminal is 0.75mm x 3.75mm, whereas the pad dimension is 1.9mm x 5 mm, with 6 mil thick of solder paste.

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Solder joint strength | 6 October, 2004

Your customer is correct. Components should not fall a board during a reasonable drop test.

A shear test poorly represents a drop test. A drop test represents a drop test very well.

If you want to proceed with shear testing, search the fine SMTnet Archives. There certainly has been discussion on this type of testing previously. The "typical numbers" for shear testing a particular component that anyone gives you are meaningless. The numbers are driven by the rate shear, setup of the test, and configuration of the component being sheared; not the material or size of the solder deposit as you would expect.

Consider sending these boards to a failure analysis laborator to better understand why your solder is not holding well.

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Solder joint strength | 18 October, 2004

I have had similar problems and my customers have had this too. A two story drop test was made by one of my customers and they found that changing Sn63 solder to Sn62 solder made a significant impact. There is no real downside other than a slightlyhigher cost, otherwise printing and reflow were unchanged. Sn62 in a pull test is always significantly higher. Try it! DenisM Manncorp

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