Not all LED are made equal. Lumiled got heat sink possiblely with GaN? The other is quantum well? Just a guess. Cheap is bad usually.
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Sent using BlackBerry
----- Original Message -----
From: Michelle Masaitis [mailto:[log in to unmask]]
Sent: Thursday, November 18, 2010 08:41 AM
To: [log in to unmask] <[log in to unmask]>
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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