Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


SMT LED functional failure

Vijay

#24158

SMT LED functional failure | 16 April, 2003

Hi , We are using water wash solder paste to solder the SMT LED's manufactured by Chicago Miniature lamp (CMD93-21 & 22)and Kingbright. Achieving the solder fillet , wetting has no issue but we observe high fallout at the functional testing. If we do some touch up on the LED's leads the the LED pass the test. We are controlling the LED's storage and handling conditions recommended by the manufacturer. Note the the LED's are solderd on the ENIA(Electroless Ni/Immersion Gold) pads finish.

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#24164

SMT LED functional failure | 16 April, 2003

Given that the LED work properly after being touched-up and that you don't have problems with other components, you may not be wetting the LED termination solderability protection during your normal reflow. Use a profiler to check the temperature on the LED. The LED may not be getting warm enough.

[Upon critical examination, that you're having this problem with two LED component suppliers complicates this theory.]

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Vijay

#24173

SMT LED functional failure | 16 April, 2003

Hi, I have taken the profile.The peak temp. at the lead terminal is 219 degc, duration above MP 54 sec and duration 125 deg C-160 deg C is 60 sec.

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#24179

SMT LED functional failure | 17 April, 2003

You'd think 219*C should be warm enough, but we'd go higher just to get the part to stick.

What is: * LED terminations material? * Alloy and flux type of your solder paste?

Is you solder sticking to the pad and not to the component? Or what?

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