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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Miss Prints

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Jim

#56341

Miss Prints | 4 September, 2008

Can someone tell me what is the best way to clean miss printed PCB? We do not have a board washer and would like to know what are the best wipes to use.

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#56342

Miss Prints | 4 September, 2008

Wipe away all you want, if you look at your board under magnification you'll still see some paste stuck on your board. I guess it depends on what you consider clean to be. Most alcohol wipes will work fine, but only a form of washing will truly get ALL the paste off.

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#56344

Miss Prints | 4 September, 2008

Surface wiping will not clean your board. Look under a scope and you will see paste in the vias.

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#56347

Miss Prints | 4 September, 2008

Uh yeah,I just said that.

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#56350

Miss Prints | 4 September, 2008

no, you said on the board, did not mention anything about in the vias

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Jim

#56351

Miss Prints | 4 September, 2008

We use Alpha 5100 no clean paste. What kind of washing would you recommend to get all the paste off the boards?

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#56352

Miss Prints | 4 September, 2008

WOW..... last time I looked, vias were a part of the board.

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#56354

Miss Prints | 4 September, 2008

Some use small cleaners but I have always used the stencil washer. Most stencil washers come with a basket of some kind of board holder (or via holder - depending on how technical you want to get). Buying a stencil cleaner is hard to justify just for miss prints, thus the reason some people buy the ultra-sonic bench model cleaners. Do your homework and see. Most vendors will clean a sample board for you.

I have seen that wiping is a killer and no washer will get all the paste off after wiping. If you simply take the miss printed board and clean it without wiping, you get better results. Granted I have not tried wiping and letting a board sit in a cleaner for days on end. I have always worked in paces that want a miss printed board cleaned in under 15 minutes - thus the reason I use a stencil cleaner. Have always used ISO to clean the stencils and boards (and vias) with also. If your flux medium is alcohol based, it makes sense to do so. This doesn't mean you cannot use other chemistries. Just what I choose to use. And yes I know ISO is flammable and you "cannot use it in a sten-sa-mable machine" blah blah blah.... but there are companies that make all pneumatic machines so there is no electronics to start a fire.

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#56356

Miss Prints | 4 September, 2008

How do you clean Miss Prints? Thats easy ask her to take a shower with ya! haw ha ha ha ha !

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#56358

Miss Prints | 4 September, 2008

Jim, There are several articles on Misprint cleaning at http://www.smartsonic.com/article.html including the "Stencil and Misprint Cleaning Handbook" by the IPC.

Real Chunks, We have replaced several pneumatic stencil cleaners over the years that were using IPA and other flammable solvents and exploded even with the electronics remotely located. The ignition sparks don't always originate from the stencil cleaner electronics. In Richard Clouthiers article, "SMT Stencil Cleaning: A Decision That Could Impact Production" he describes how a "static" spark or a spark from surrounding equipment or a mechanical spark caused by a loose fixture, etc. can cause an explosion. It sounds like you may be a fire waiting to happen.

A copy of Clouthiers article is also available at: http://www.smartsonic.com/article.html Read the section "Select the Chemistry First".

Regards, Bill Schreiber Smart Sonic Corporation Bill@SmartSonic.com

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#56366

Miss Prints | 5 September, 2008

We manufacture a low cost machine completely Air driven for Misprints only but dont have an agent in the USA unfortunately or could have demo'd it for you They do work very well with IPA derivative cleaners but IPA on its own is very poor. Best method is not to wipe it at all and immerse in solution for three/Four minutes then wipe while agitating, if having to hand clean. If you want details on ours I would be happy to mail you details and pricing. Had no fires so far machine is earthed and larger one has conductive pumps so no reason to suffer fires. Cheers Greg York BLT Circuit Services Ltd England

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