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February 2014

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Subject:
From:
"Robert e. welch" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Thu, 20 Feb 2014 21:32:09 +0000
Content-Type:
text/plain
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text/plain (203 lines)
Acetone should not be used accept for women's nail polish remover.  
Just wanted to point out that most air dry test stamps(ET,QA etc.) are black and will definitely be removed by acetone.
Just tried one and it looks just like the photo.
We keep a small (controlled) amount around for removing nasty things like black ink on copper laminate.
Most large scale uses of all the Ketones were made problematic in our industry many years ago with the passage of such things as "the clean air act" and the "clean water act:".  Not to mention all the NIOSH/OSHA restrictions.   I sure do miss the MEK we used in past.  They say it's bad for your brain, but I'M OK,OK, OK, OK.
I would indicate to your customer that you are required (per ISO perhaps) to preserve these markings for traceability and get some specific recommendations from some of these assembly/cleaning gurus.

Robert E. Welch
Senior Process Engineer
Moog Components Group

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert DeQuattro
Sent: Thursday, February 20, 2014 3:49 PM
To: [log in to unmask]
Subject: Re: [TN] Acetone as a cleaning agent for PCBA's

Of course my permission to post the picture has been granted.  It is apparent that using the acetone is not a good approach and worse, that the residue may be from breaking down of the PCB laminate.
So next question, how can I tactfully inform the customer of this and best direct him to a more appropriate method?
Several of you have hinted on better technologies.

Bob

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Thursday, February 20, 2014 3:35 PM
To: [log in to unmask]
Subject: Re: [TN] Acetone as a cleaning agent for PCBA's

Hi Doug and Bob,

Here's the pic:

http://cp.mcafee.com/d/k-Kr4zqb9EVjd7arPX3VKVJBUsYMzt4SOYeuohoKrpu7fc8TpdICzCXbzRTPskf5CZDedgkpza23t9NBZendCoOwwTispvjBPqaoVNOXb_nV5Vx5NV7HTbEILEYCUqerI9EYJt6OaaJNP_axVZicHs3jq9J4TvAm4TDNOb2pEVdTdw0WjYPUFVDu9Rl-A_R3BY6b4RmVyD2aN4TkN3UBV_oC3gl9qT00jqdS61NI5-Aq83iS2goqnjh08m-touq8dEq8dd45z_S4E4jh1F7Ujd43JoCy0b2gO86yuxJwsrPIz3yYdD

You're right that is some serious looking schmutz! Almost looks as bad
as the Stridex pads I used when I was a teenager.   :o)

Seriously, that acetone is breaking something down and I don't think it's anything good.

Steve 


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
Sent: Thursday, February 20, 2014 12:52 PM
To: [log in to unmask]
Subject: Re: [TN] Acetone as a cleaning agent for PCBA's

Bob sent me a picture of what the wipes look like after the acetone wipes. 
 I have forwarded it to Steve, and with Bob's permission, to put on Steves web page.

There is some serious schmutz here.  Bob, a couple of questions - is the solder mask dark in color or is it the garden variety green?  Are the legend and marking inks dark and are they smeared or blurred after the acetone wipe?  Is it a light wiping with low pressure, done by Millie the Mouse, or heavy cleaning by Magilla the Gorilla?

Has anyone thought to analyze the wipe cloths by FTIR to see what the chemical signature of the schmutz is?

Doug Pauls



From:   Robert DeQuattro <[log in to unmask]>
To:     <[log in to unmask]>
Date:   02/20/2014 12:19 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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