Hi Michelle! Are you cleaning the LED assembly/components in any manner? 
LEDs do not play well with many cleaning processes or cleaning 
chemistries.

Dave Hillman
Rockwell Collins
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Michelle Masaitis <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
11/18/2010 07:41 AM
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Subject
[TN] Led Failures Please help






-   the through-hole LED in question is made by company "EOI ", and their 
part number is  "EOZ-ZARNCD0-DG " (s 
-   according to the component spec sheet  (enclosed), the maximum 
temperature for the component is 260℃ 
-   the maximum temp and wave contact time we initially used is  249℃ , 
4-6 
seconds.  We saw some defects after first pass, usually about .2%, but one 

month as high as 1.5%.   After successful testing, there were then some 
latent defects that occurred at our customer or their end customer.  The 
defects are erratic, sometimes the LEDs work, and sometimes they don't 
-  the supplier recommended a lower temperature and shorter exposure 
profile 
so we used SAC305 solder with maximum temp of 244.4℃ and 3 seconds. 
There 
were no defects after first pass and testing, but again we had some latent 

defects occur at customer 
-   for reference, we run many similar LED from other manufacturers 
(OSRAM&Lumiled, also spec at 260℃) at temperatures of 251℃ and 4-7 
seconds 
and see no such problems. 

Attached is a wave profile.

Please let me know if you seen a similar issue and what caused it.


Thanks

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