So here's an interesting bit of information to add to the conversation.
First, this is how the customer described this cleaning process:
"Parts all layed out on blue mat on table and then the front washed with lint-free cloth with small
amount of acetone applied to it as we have always done. These parts were very dirty and
needed more washing then usual. Did not detect any damage to parts."
After discussions here, we believe that by front, they are referring to the open PB63 SN37 plated side of the board that they adhere an overlay to.
So this would indicate that the acetone is being used to clean this open plated side to affect good adhesion.
This feedback from the customer is all new to us and is the result of us asking them to review their handling procedures due to a trend of returned product that was defective due to some sort of handling damage.
All this product passes testing prior to shipment. Tracking their returns, we identified that after our testing, each of our shipments of approximately 60 assemblies was resulting in 2 or 3 boards returned for either broken, damaged LED's, or trace damage on the open plated side of the board. We thoroughly investigated our handling and packing procedures on our end and didn't see any potential causes, so we shared our information and asked them to review their process. This is when they informed us of this cleaning. Aside from the potential implications of this cleaning / handling activity, the use of the acetone raised a flag that I thought would be worth fielding to you all - so now here we are - you know almost the whole story......LOL!
Bob
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Thursday, February 20, 2014 3:56 PM
To: [log in to unmask]
Subject: Re: [TN] Acetone as a cleaning agent for PCBA's
Dave,
Thank you. A tiny amount on a Q-Tip works so well that I did not want to see it simply dismissed!
Anyone with a big enough container to dunk a PCB into acetone is, as my Dad would say: " Cruisin for a Bruisin ". :-)
Bob K.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Thursday, February 20, 2014 3:08 PM
To: [log in to unmask]
Subject: Re: [TN] Acetone as a cleaning agent for PCBA's
Hi Bob - No, that specific amount in that type of procedure should not be an issue. But the fact that there is sufficient industry data showing that acetone attacks the butter coat, potentially attacks the laminate and that I have alternative cleaning chemistries that do not cause possible damage is reason enough for me to not use acetone. I tend to try and design processes that are "Hillman proof" as sometimes materials get misused unintentionally.
You are using a specific, controlled procedure but another person who is not as diligent or knowledgeable may use the acetone in a less than acceptable manner causing damage. Just a case of "risk versus reward" where I have alternatives that eliminate the risk.
Dave
From: "Robert Kondner" <[log in to unmask]>
To: "'TechNet E-Mail Forum'" <[log in to unmask]>,
<[log in to unmask]>
Date: 02/20/2014 01:59 PM
Subject: RE: [TN] Acetone as a cleaning agent for PCBA's
Dave,
Do you think using two drops on a Q-Tip for cleaning with the acetone evaporated in 5 seconds is going to hurt a board?
Bob
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Thursday, February 20, 2014 2:14 PM
To: [log in to unmask]
Subject: Re: [TN] Acetone as a cleaning agent for PCBA's
Hi Bob - Acetone has the potential of damaging your laminate (see Richard's
reply) and I would not recommend it as a cleaning solvent.
Dave
From: Robert DeQuattro <[log in to unmask]>
To: <[log in to unmask]>
Date: 02/20/2014 12:20 PM
Subject: Re: [TN] Acetone as a cleaning agent for PCBA's
Sent by: TechNet <[log in to unmask]>
Thanks all on the comments.
This is a picture of what the residue looks like from the acetone cleaning process.
[cid:[log in to unmask]]
Based upon the replies at this point to this thread, it appears:
1. Using the acetone as they are seems acceptable for cleaning
2. The boards we are supplying have some type of residue on them
regardless of the results of the zero-ion testing.
Bob
-----Original Message-----
From: Mike Fenner [mailto:[log in to unmask]]
Sent: Thursday, February 20, 2014 12:56 PM
To: 'TechNet E-Mail Forum'; Robert DeQuattro
Subject: RE: [TN] Acetone as a cleaning agent for PCBA's
Hmm
I think I would like to know what their wiping procedure is and what they are hoping to achieve by doing it before making any firm comment.
Naturally nothing has changed in your place or theirs, but something has if this has just started to appear.
I would start from the premise that the boards can be no cleaner than the last thing that touched them.
Unless the acetone is being allowed to flush off the board the probability
is that they are making the boards dirtier. If there is anything in the acetone or on the board and it dries in place then the board will be no cleaner than it was before (the soil might be redistributed slightly) and anything in the acetone or on operators gloves will be left on board. If they are applying the acetone to the wipe by holding it against the bottle
then anything in the wipes will gradually accumulate in the bottle.
Quite likely they are just seeing a surface effect as you would get on any
shiny surface wiped over like this. Think of cleaning a mirror. So it could be technique or the acetone is dissolving something from the wipe or
softening the resist slightly. OR your boards are contaminated from packaging say and they are seeing partial removal. In this respect the boards could be ionically clean as measured by zero ion tester, but theoretically could have non ionic contamination.
So a lot of what ifs and maybes at this point.
Regards
Mike
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert DeQuattro
Sent: Thursday, February 20, 2014 5:00 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: [TN] Acetone as a cleaning agent for PCBA's
I have a customer that uses acetone to wipe down their PCBA's upon receipt.
The assemblies we make for them are cleaned using a closed loop aqueous board washer then sampled for cleanliness with our zero-ion tester per J-std-001E guidelines.
Recently this customer commented that boards appeared dirty upon cleaning with the acetone. Does anyone have any thoughts on this acetone cleaning process.
Thanks,
Bob
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