Sometimes hot melt is used instead of the conformal coat over uncleaned
no-clean fluxes.
The hot melt cures in the cycle time between operations.
The applications include products that are lasting 15 or more years in -40C
to 85C applications.
The products are shipped world wide to untrained end users.
These products have flux residues from liquid fluxes, pastes and solder
pastes..
The amount of residue varies greatly.
The buyer of the product has many QE's and lawyers and will lean heavily on
those that cause recalls of their product from the end user.
I.e., don't make the front page of the paper with your defect, as some have.
This product and many similar ones go into an end item worth $15k to $150k
Measurement of local flux residue is not part of the contracts.
It is an area that could stand improvement.


The BGA with poorly vented metal lids(heat speaders) were made with no
clean process.
Most are used in no clean processes.
Just another example of the unintended consequences of using a part out
side the typical design application.


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________