MSL level 6?  are those intend for hand soldering?  Did you have  
product (components) application note? does it come with recommended  
reflow profile?  (not from your CM, but from LED MFG).
what is the reason your design team  select MSL 6 components for the  
design?  Unique wavelength?  low profile, or optical properties  
superior? (unless both, or no alternative, design don't touch MSL 6  
by long pole).
jk
On Sep 9, 2019, at 3:42 PM, Dave Schaefer wrote:

> James,
>
> Thanks for the quick reply.
>
> The components in question are from a single manufacturer and are  
> MSL6 devices. They are properly stored and processed by the CM;  
> have verified the appropriate pre-bake and reflow profile are being  
> used. The majority of the failures we have seen are instant hard  
> failures after bare board assembly but we have seen a few creep  
> through into final assemblies. At this point I believe all  
> components consumed are from a single lot from the manufacturer. I  
> have reached out to the manufacturer in an attempt to determine how  
> they assure component quality prior to shipment but they have not  
> shared any information of value.
>
> Thanks,
> Dave