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LED (Seven Segment) found with missing segment and dimmer

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#64671

LED (Seven Segment) found with missing segment and dimmer | 20 July, 2011

I have mount the 8 pcs SEVEN SEGMENT LEDS on the PWB side at SMT Process, after reflow the board test at customer side and facing some issues which is missing segment and also one segment founded dimmers compare to other segment.

Data sheet of LEDs is mention the max temp is 260deg C, then I set my reflow profile to go in max 210 DegC. After that change the process to manual solder, with temp 240degC, but the result remain a same from customer...

Any one of yours facing the same issues with me ? and how to prevent this issues happen again in future run ?

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aci

#64673

LED (Seven Segment) found with missing segment and dimmer | 20 July, 2011

Umar - This is usually seen when the lead frame in the die attach is cut with a diamond saw instead of a lasar. We have seen this problem years ago from HP 7 segment displays. If you have Enviromental box (tenney box) you can temp cycle them from 0 degree to 100 C. You must cycle them four times each way under power and whatch for the change in brightness. If you see a change then they were cut with the incorrect process. www.americancircuits.com

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