Reply to: RE>ENTEK 106
Peter:
Although I did not respond to the initial e-mail, I do have some caveats for
Entek users to share with the "Net", based on personal experience:
1) If the PCBs are left in the microetch too long prior to ENTEK application,
the underlying copper (especially in the vias) is dissolved and can cause
intermittent operation or "hard" opens when the assembly heats up.
Recommendation: 100% electrical test AFTER ENTEK application.
2) Along the same lines, "strip and reapplication" of ENTEK should NOT use a
predip microetch, unless the boards are 100% retested after the reapplication.
If the original copper is thin, additional microetching could create open
vias that will go undetected during final visual inspection. Recommendation:
Try stripping ENTEK with IPA followed by DI rinse, rather than microetch. If
this does NOT correct the condition, refer to item 1 above.
3) The drying step is very important! If the boards do not go through a
post-ENTEK bake and are placed in plastic bags, the moisture left in the vias
will seep into the bag during shipping and cause "water spots" or thin areas
of ENTEK that could promote localized oxidation, which is detrimental to good
solderability. Recommendation: Have bare boards baked by PCB vendor prior to
final packaging for shipment.
IMO, ENTEK-106 is STILL the best choice for fine-pitch SMT designs, in spite
of these "caveats".
Bill Fabry
Process/QA Mgr
Truevision, Inc
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--------------------------------------
Date: 11/4/96 10:03 AM
To: Bill Fabry
From: peterb
Jeffery Harry, would you please expand on the "major problems" you
have seen by running Entek 106 in a dip mode.
Peter Blokhuis
PC World
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If you use Entec 106, make sure that the PCB supplier has an in-line
process. Dip tanks will cause major problems. Also the PCBS need to
be thoroughly dried before packaging. If not, you will have
solderability problems.
Jeffrey_Harry @ 3mail.3com.com@ ugate
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To: Technet @ ipc.org @ UGATE
cc:
From: EHolton @ vines.etn.com @ UGATE Date: Thursday October 31,
1996 02:40 PM Subject: OSP Coating
----------------------------------------------------------------------
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---------- ------------------------------
Fellow technetters:
My company is beginning its research into the wonderful world of
organic solderability preservative coatings. Our goal being to
implement this on the circuit boards in the near future. I am looking
for any and all information that anyone may have....
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