Steven
The specific component types that were concerns for this cleaning method per the DoD studies were TO package IC's (not used much these days). Later testing by the EMPF looked at encapsulated components with better results, should still be available for review but I don't believe that the DoD studies are.
 
Mel Parrish
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Creswick, Steven
Sent: Wednesday, January 02, 2002 8:17 AM
To: [log in to unmask]
Subject: Re: [TN] Ultrasonic Cleaning

From a hybrid manufacturing standpoint we found that if the wirebonds are surrounded by the ultrasonic cleaning fluid there is no problem.
 
However, if there is a cavity - there will be a problem.
 
Put another way - ultrasonic cleaning of sealed units (nothing but dry nitrogen around the wires) was an open invitation for non-functional units.  Cleaning of un-sealed units was not a problem.
 
Most plastic encapsulated devices have no (intentional) air pockets around the wires, therefore, I would expect them to be okay.  If you have sealed metal can type packages I would stay away from the ultrasonics.
 
Steven Creswick - Gentex Corporation
-----Original Message-----
From: Dieselberg, Ron [mailto:[log in to unmask]]
Sent: Wednesday, January 02, 2002 10:26 AM
To: [log in to unmask]
Subject: Re: [TN] Ultrasonic Cleaning

I had only one experience, about 15 years ago. The assembly tested OK before cleaning in an ultrasonic tank. Afterwards it did not work. Failure analysis folks said almost all of the wire bonds in the three transistors were damaged.. Maybe someone has had good luck, but not me. That was the first and last on anything but a component-less board!

Ron Dieselberg
Trainer/Auditor
CMC ELECTRONICS
CINCINNATI
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