Phil,
Aren't "cans of worms" TechNet's bread and butter?
You say presumed problematic. How solid is that presumption? Any evidence?
Why machine wash at all? Why not used a fully qualified no-clean and leave
it at that? Or are you building for space, medical or military? Or do the
optos require it?
For your CMs how are you setting the cleanliness standard? ROSE (yuck),
modified ROSE (yuck again), SIR/ECM?, ion chromatography?
Regards,
Bev
-----Original Message-----
From: TechNet <[log in to unmask]> On Behalf Of Nutting, Phil
Sent: June 20, 2020 10:04 AM
To: [log in to unmask]
Subject: [TN] installing and hand washing as a final step
Hi All,
I hope you have all been able to avoid becoming ill.
We have found some components (presumed) to be problematic when machine
washed. Avago optos, TI PTH logic (yes, we still do thru-hole), film
capacitors, trim pots and some other components are usually the offending
parts. These components are then designated to be hand installed, soldered
and washed after the boards are machine installed, solder and washed.
I fear the '70s are coming back.
About 80% of our PTH boards and 100% of our SMT boards are built by CMs. We
do not specify solder, flux or cleaning systems. We do however specify
lead-free and a cleanliness standard. In-house PTH boards are washed in a
closed loop batch DI washer.
I'm not a fan of switching to hand solder and wash for the simple reasons of
hand soldering is less consistent and hand cleaning may just spread residue
to a wider area.
I know I'm possibly opening a can of worms for process control, water
pressure, wash chemicals, choice of flux/paste. Is this a common
manufacturing solution? To me this is like fingernails on a chalkboard.
Phil Nutting | HVP Senior Development Engineer | Excelitas Technologies
Corp
Lab: +1 978.224.4332 | Office: +1 978.224.4152
35 Congress St, Salem, MA 01970 USA
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www.excelitas.com<http://www.excelitas.com/>
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