Electronics Forum | Thu Jan 06 10:56:32 EST 2005 | Rob
If the Leds are not in close proximity then LDR's can be used connected to a node on the ICT/wired into a micro for a simpler board - you can then test for luminous intensity as well as absence. Else you could use a cheap CCD camera with some simple
Electronics Forum | Thu Mar 18 11:07:45 EDT 2010 | mun4o
hi, lately I have problem with smd leds.After reflow 2-4% of leds are broken.I think , that reason is bad storage of components, because in our stock the tape with leds have not Moisture Barrier Bags.My question is ,how you storage components, which
Electronics Forum | Thu Mar 18 14:33:46 EDT 2010 | jdumont
Is your peak reflow temp exceeding the LED spec? We store our SMT LED reels on the rack with the rest of the discreets and have never seen this issue...
Electronics Forum | Mon Mar 22 10:24:14 EDT 2010 | mun4o
Hi , I think that our problem is humidity, because when I use leds from new tape ( pack in MBB ) no any defects.After that, we put opened tape in our store.After 2-3 weeks I use the same tape with leds, and we have 2-3% defective leds.I make this tes
Electronics Forum | Fri Mar 19 07:18:14 EDT 2010 | grahamcooper22
Hi, do you know if your LEDs are moisture sensitive ? And if so what MSL level ? Surprisingly it seems that not all are, but some seem really sensitive. I imagine the differences are down to the plastics used and the LED manufacturing processes. I a
Electronics Forum | Fri Mar 19 03:13:35 EDT 2010 | mun4o
Hi, First check what the Moisture Sensitivity > Level of the LEDS is....you may need to ask the > LED manufacturer. Once you've established it is > moisture sensitive then follow latest version of > IPC JEDEC 33 spec. for storage of them and dryi
Electronics Forum | Fri Mar 19 09:22:32 EDT 2010 | mun4o
Hi, most of them are MSL 3.There are MSL 4 and 2a.Most of defective LEDs are 3528 footprint.The thermoprofile is Ok??
Electronics Forum | Tue Mar 23 03:42:51 EDT 2010 | grahamcooper22
Hi, It is very important to follow IPC JEDEC 33 specification for storage and handing of all MSDs. In many instances defects caused by excess moisture in packages is not immediately evident (pcbs may pass final test) but when pcb has been in the fiel
Electronics Forum | Thu Mar 18 18:07:21 EDT 2010 | grahamcooper22
Hi, First check what the Moisture Sensitivity Level of the LEDS is....you may need to ask the LED manufacturer. Once you've established it is moisture sensitive then follow latest version of IPC JEDEC 33 spec. for storage of them and drying them if t
Electronics Forum | Fri Mar 19 03:50:37 EDT 2010 | grahamcooper22
Some things you have to be sure of... Can you guarantee the LEDS are DRY when you receive them ? They may be packed in dry bags but when was this done and has the LED distributor had them open at his site ? Using vacuum sealed dry packs is a good way
