It could be a problem related to the component MSL and proper handling. Many led's are MSL 4 which gives these components only a 72 hour floor life outside of their special moisture barrier bag packaging before special handling (normally baking) is required. The first step is to find out the component MSL. Then you can refer to J-std-033B for details on how to handle.
Bob DeQuattro
Quality Manager
VR Industries, Inc
333 Strawberry Field Road, STE 6
Warwick, RI 02886
Tel: 401-732-6800 ext 45
Fax: 401-738-7910
[log in to unmask]
www.vrindustries.com
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Michelle Masaitis
Sent: Thursday, November 18, 2010 8:42 AM
To: [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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