I would say that a mild acid etch probably would be more aggressive in removing a wider array of contaminates that the flux. Unless it is a inorganic acid flux (zinc chloride/HCl) even a water soluble flux would not be as effective in oxidizing and removing other soils prior to the HASL process. In addition, the acid bath probably can tolerate a higher soil load than a flux bath- so the bath would last longer and require less changeover (less raw materials and waste stream).
From a contract assembler standpoint we would welcome it and a prudent measure. With Receiving Inspection not viewed as a "value added activity" most problems are now found on the production floor- how about that as a poor management philosophy but hard to predict rework so hard to justify the expenditures. Sorry will get off my soapbox.
Tom
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Louis Hart
Sent: Friday, March 21, 2008 12:07 PM
To: [log in to unmask]
Subject: Re: [TN] SV: [TN] preparation for HASL
Thanks for your help, Inge. It got me thinking about greasy fingerprints, however. The engineers here tell me acid will not remove fingerprints. And this precleaning process uses acids. Supposedly alkaline cleaning removes fingerprints.
Louis
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hfjord
Sent: Friday, March 21, 2008 11:04 AM
To: [log in to unmask]
Subject: [TN] SV: [TN] preparation for HASL
Agree. Solder flux is for oxides, remember! Solder flux does not take grease! At least what I have learned. There may be formulas that take even grease, but we don't have them.
/Inge
-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För Lee parker
Skickat: den 21 mars 2008 15:36
Till: [log in to unmask]
Ämne: Re: [TN] preparation for HASL
Louis
I would continue the process as you are currently doing. You can never be too clean or too rich.
Best regards
Lee
J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389
----- Original Message -----
From: "Louis Hart" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, March 21, 2008 10:20 AM
Subject: [TN] preparation for HASL
TechNetters, a question has come up in our plant about cleaning copper surfaces before HASL. (Solder used is the standard tin-lead.) We've been putting panels through a light acid clean and etch, then through a Quicksilver flux applicator with two rollers that appear to be saturated with Enthone 757 SG flux. Someone has asked if that acid clean and etch are really necessary, since what is flux supposed to do?
Any comments on the need for the acid clean and etch would be most welcome.
Many thanks - Louis
Louis Hart
Compunetics
Monroeville, PA
USA
[log in to unmask]<mailto:[log in to unmask]>
412-858-1272
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