It would be in the component SCD (part print), as different LEDs have different thermal transfer and electrical grounding requirements.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Fenner
Sent: Tuesday, September 11, 2012 2:32 PM
To: [log in to unmask]
Subject: Re: [TN] LED Ilumination Voids

I'm not aware of any International Specification. If there were to be one it would be JEDEC rather than IPC. JEDEC is concerned with component manufacture and there may be something you could use as the basis for your own needs. More likely would be manufacturer app notes. 
Generally speaking void levels in heat generating/power devices are kept rather lower than you would find acceptable in BGA: 5-10% or less. This is a statistical thing though to minimize the chance of voids coinciding in the "stack" of assembly layers (die to substrate, substrate to heat sink and so
on.) Thus, though an individual void might not be significant on its own, if it were over a lower layer void the combination could cause a hotspot.
Company process specifications usually take the form of "total voiding no more than X% with no individual void greater than Y%". There is a certain amount of arbitrariness in level setting, the need being to set an inspectable process control rather than outright functionality.

Hope this helps.




Regards


Mike Fenner

Bonding Services & Products
M: +44 [0] 7810 526 317
T: +44 [0] 1865 522 663
E: [log in to unmask]

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Juliano Ribeiro
Sent: Monday, September 10, 2012 1:12 PM
To: [log in to unmask]
Subject: [TN] LED Ilumination Voids

Hi to all,
We have IPC (e.g.:7095) for BGA and voids percent not allowed. But for LED Ilumination, is there rule (IPC documentation)? We can use the same criteria for BGA, in the void case?
We are soldering LED and when we inspected with X-Ray, the quantity voids in the soldering is elevated so we didn´t know define the ok percent.

Thank you

Juliano Ribeiro
Coordenador de Produção - Placas Eletrônicas Elo Sistemas Eletrônicos S.A.
Fone: (51) 2131 2217    Fax: (51) 2131 2200
Cel: (51) 9356
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