Rich,
That is correct. We call it a 'Pick Test'. It allows one to test a much
smaller area than with the tape test method. It is still somewhat
subjective, eventhough a number is assigned. But, once the tester
experiences the different ranges of adhesion, there will be little doubt
as to what a '0' is (no adhesion), or a '5' (can't remove). There may be
some discussion as to if a value is a 2 or 3.
The benefit is that it is a simple test that anyone can perform without
any special equipment.
There are special tools that are nanoindenters/stylus systems that apply a
downward pressure as the stylus moves along the surface. It is possible
to get quantifiable results as to the forces necessary to cause a
separation at the coating/substrate interface. But, it is only a number,
it doesn't tell if it is good or bad. It has to be compared with a sample
that is good and bad to understand what the pass/fail results are. The
downside is that these systems are specialized and can be expensive, close
to 6 figures or more.
Lamar
Richard Kraszewski <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
05/12/2009 10:06 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Richard Kraszewski <[log in to unmask]>
To
[log in to unmask]
cc
Subject
Re: [TN] Parylene Adhesion Tape Test
At last Falls IPC Cleaning Symposium in Rosemont, IL Lamar Young / SCS
presented a paper where he wasn't using tape, but rather lifting the
squares with a needle and assessing the adhesion using a Likert scale.
He claimed the results were more consistent than tape. I think that the
testing for that presentation was actually done on parylene.
You should be able to find the proceedings somewhere in IPC.
Rich Kraszewski / PLEXUS
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Mary Lou Sachenik
Sent: Saturday, May 09, 2009 6:48 AM
To: [log in to unmask]
Subject: [TN] Parylene Adhesion Tape Test
We recently had some issues with lack of adhesion of Parylene coating
What types of notes are being used on drawings to define parylene
conformal coating adhesion test on pwa's?
Is the ASTM3359-08 (for assessing the adhesion of coating films to
metallic substrates) the best spec to call out for this testing .
I presently don't have pwb coupons to perform destructive cross hatch
test.
What type of tape is being used testing parylene adhesion on the PWA's?
Some specs call out 3M-250 tape, the ASTM D 3359 calls out the Permacel
99.
Actually I prefer the Wescorp 79210 clear Anti-static Tape, does this
seem acceptable?
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