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IPC-A-610D Question

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Tim

#41311

IPC-A-610D Question | 2 May, 2006

8.2.5.5 Flat Ribbon, L, and Gull Wing Leads, Maximum Heel Fillet Height (E).

For class 3 the heel fillet cannot touch the body of a plastic component, except for SOICs and SOTs.

Why is my question? What type of failure will be the result of solder touching the body? I expect it has something to do with stress/strain of the lead due to thermal expansion but I need some more input.

We currently use 6mil stecils should we switch to 5mil?

Thanks,

Tim

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#41321

IPC-A-610D Question | 2 May, 2006

I have experienced the exact same problem with excess solder touching the plastic component body. The solution in my case was simply to replace the stencil. I was using a reusable stencil frame that had been worn out. I replaced the stencil with a solid DC 20x20 frame and have not seen this problem since.

When I asked what the actual component failure was, I got two responses.

1. Prolonged exposure to heat causes the component to crack. 2. Thermal expansion creates stress on the lead and over time can weaken or break.

I tried calling IPC myself but didn't have the patience to wait on hold.

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Tim

#41351

IPC-A-610D Question | 3 May, 2006

Brett,

I've found out that it is not a defect with respect to Rev. D. You are correct about the thermal expansion but due to the size of the plastic SOIC's and SOT's they have eliminated it as a defect.

Thanks,

Tim

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