Re: Pcb cleaning

[Steve_88]

I'm trying to understand what is typically done to clean and dry pcb's.

I'm using a water soluable solder paste from Stencils Unlimited.
http://www.stencilsunlimited.com/product_info.php?products_id=179

After soldering, I use soapy water with a tooth brush to remove the flux residue. This works pretty well and is similiar to the much suggested

"just put the pcb's in the dishwasher to clean them"

But then how best to safely dry them? I've read that using compressed air is good enough?

Or should they be dried in the oven for a day or two at a low temperature ~ 80 to 90 celsius?

Thanks,
Steve

[skimask]

I'm trying to understand what is typically done to clean and dry pcb's.
I'm using a water soluable solder paste from Stencils Unlimited.
http://www.stencilsunlimited.com/product_info.php?products_id=179
After soldering, I use soapy water with a tooth brush to remove the flux residue. This works pretty well and is similiar to the much suggested
"just put the pcb's in the dishwasher to clean them"
But then how best to safely dry them? I've read that using compressed air is good enough?
Or should they be dried in the oven for a day or two at a low temperature ~ 80 to 90 celsius?
Thanks,
Steve

From what I got from that class I went to last year, as far as cleaning paste, flux, etc, the 2M level 2 answer is and always has been iso-alcohol. But then again, this isn't a space station manufacturing facility :)
As far as drying the PCB's, now that answer, according to the books and the old guys at the school, has always been 120F-140F in an oven overnight. PCBs, parts, components, whatever.
Something else I didn't realize until I went to that class...
Say I go out and buy a package of 100 PIC's tomorrow, doesn't matter which type, may as well be 100 pack of 10K 1/4 watt resistors. Well, turns out those things are only supposed to be laying around for a limited time, especially with IC's. Moisture collects, rust starts, and so on and so on...hence the baking before using them.
I dunno...sometimes it all seems like magic...

[Steve_88]

Skimask,

Thanks that is very helpful.

Regarding pre baking the parts to remove moisture, this makes sense.

I'm always interested in what the "old school folks" do, in fact I'm probably considered one of those "old folks"

Now if we could use PBPro to create an anti aging system......lol

Regards

[falingtrea]

FYI, part baking is required for parts used in IR solder systems, if they have been unsealed for a certain length of time. Any moisture in the part could cause case cracking when that part is raised to 260C very quickly, as is done in an IR soldering system.

As for drying boards after cleaning, they could be air dried without any problems, if you have the time. Oven drying is really only necessary if you are planning to conformal coat the boards or if you need them dry real quick. Time is money on an assembly line.

[Steve_88]

Thanks, the information is appreciated

Regards

[Melanie]

We use a chemical called ARKLONE (specifically ARKLONE-L) manufactured by ICI. The boards are then blow-dried by compressed air.

ARKONE-L has a very low boiling point, and at room temperature, you can see 4 inches (10 cm) of heavy vapour floating on top of the liquid in the tank (a lid is a must otherwise you end up on a permanent 'High' wading in the stuff!) if you put your hand in it, it'll be soaking wet long before it ever touches the liquid. As a by-product, if you stab a hot soldering iron into the vapour (c'mon there isn't an engineer on the face of the planet that doesn't play!), has a habit of forming cyanide gas which is great for getting rid of people you don't like... (always wondered why the Hells Angel types want to work in that department).

[Steve_88]

Sounds like fun, and I'm always looking for ways to displace co workers etc.

I've often wondered, let's say I have a raccoon taking up residence at my dwelling. Technically and legally I could have someone "relocate it" for me........

Surely we should be able to do the same with humans?

[Melanie]

It's been done... I think they called it 'ethnic cleansing'.

[Steve_88]

Melanie,

I was thinking of something a little more friendly, makes me sad thinking about it thanks... ;)

What type of pre baking of the IC's do you typically do, if any?

Thanks,
Steve

[Ron Marcus]

I worked for an Electronics R&D house some years back. They had a tank with a bath of tetrachloroethylene liquid. The top of the tank had a band of refrigeration coils, and the bottom was slightly heated. It created a fog that would hang in the tank just below the lip. We would hold a basket of pcbs suspended in the mist and they would be cleaned in just a few minutes. Extremely cool technique. Alas, Tetrachlor would make labratory rats explode on contact, so it's hard to find nowadays. Stupid rats!

[Luciano]

Hi,

See this document:

Stencil and Misprinted Board Cleaning Handbook
http://www.smartsonic.com/IPC7526Handbook.pdf

Best regards,

Luciano