Don,
I'll take a crack at this one having lived through the qualification process
twice. I had to do this for an aerospace manufacturer (circa 1993-1996),
getting customer process certification from the Navy and NASA...
To prove that the cleaning process was repeatable and provides good cleaning
results, we had to perform a series of tests above and beyond using an
omegameter. We provided data to our customer using Ionic Chromatography,
SIR, and FTIR on the effectiveness, and the types and levels of ionic and
non-ionic contamination on hardware after cleaning. In addition, we provided
data sheets on how we planned to control the process. Using an aqueous
cleaning process, that included how often we monitored the DI Water
resistivity and solution concentration and the corrective action when the
process went out of control. Measuring water temperature and the wash /
rinse / drying duration are additional variables which have to documented
and monitored. If a saponifier or surfactant is used, you should check their
MSDS and Process Data Sheets to assure that the material is used properly.
Depending on your requirements, you may also want if the process is a manual
process or an automated process. I'm assuming that it is automated, but if
it is manual, then you have to determine the quality of operator training.
Assuming that your supplier properly implemented the aqueous cleaning
process, then the hardware should be coming out with cleanliness levels ~
1-2 uG NaCL / sq. in. This is well below the IPC limits specified in
J-STD-001, and if you want to go WAY back, the MIL-STD's and NASA
specifications. With good process control, the aqueous cleaning process
should work in an aerospace application.
If there are any questions or comments, call me off line.
Hope this helps.
Good Luck.
Lee Whiteman
Senior Manufacturing Engineer
American Competitiveness Institute
E-Mail: [log in to unmask]
Ph: (610) 362-1200 x208
Fax: (610) 362-1290
This message is for informational purposes only and does not supersede,
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Donald Vischulis
Sent: Thursday, March 09, 2006 5:59 PM
To: [log in to unmask]
Subject: [TN] Cleaning Qualification Question
All
I've been assigned the task of determining if a supplier's current cleaning
process is robust or if additional testing is required to be able to say
that the product is clean enough to provide years of field use. The board
is a 2-sided Class 3 assembly (95% SMT) with one BGA and about 1500 other
components. The assembly is soldered with a water soluble flux, it's cleaned
in a batch cleaner with DI water, and is conformal coated. The current
manufacturer is using and Omega meter to verify the cleanliness of the board
after cleaning.
My questions:
Is this process good enough to provide a reliable product in an aircraft
application?
If not what guidance is available to determine what level of process
qualification is needed to answer question #1?
Any help is really appreciated.
Don Vischulis
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