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Components Turn Yellowish!

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Components Turn Yellowish! | 20 August, 2005

Hi There, Good Day 2 Every1.:)

I'm in mid of issue of SMT Components (Resistor & Capacitor) Turn Yellowish issue after reflow oven. Is there anyone have handle this issue previoslly and what is the reason behind the components behaviour in such. Can anyone let me know,the possiable rootcause and why this happen. Let me share few more things, The parts temp withstand is 260degree,less then 15second hence, the temp profile that we set is peak at 235deg only for reflow oven. I'm dicusssing with the supplier on this issue which yet to receiveing any solid solution. Can someone let me know and share your thought on this issue. Thank You.

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Components Turn Yellowish! | 22 August, 2005

We see this after exceeding the maximum temperature of the component.

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Components Turn Yellowish! | 22 August, 2005

We've also seen it where a component has had a long soak at a high temp (last one was 220C for 1.5 minutes)without exceeding PBT. The long soak was due to the oven only having 3 heated zones.

On the last occasion there was some concern over the leadfree status of the affected parts (resistors). We changed brands & used leadfree stock & the problem went away.

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