Favorite PCB cleaners

Ethanol works better than IPA on the fluxes that I use (RMA and RA).

One of the main problems is getting flux out from under SMD resistors and caps.

Cheers

Phil Hobbs

Big fine-pitch BGAs and tiny flat chip-scale parts are even worse. An inch or so square FPGA with 750 solder balls is a perfect hiding place for flux.

A wonderful opportunity for using hydrogen or forming gas in your reflow oven. ;)

Cheers

Phil Hobbs

Anhydrous Isopropyl. Methyl Alcohol.

Hey, John - you ever try ethanol in your water pic?

John S

How is a few seconds of vapor drip going to work its way under a square-inch, 1000 ball BGA, and dissolve and remove the flux from the inner balls? It's not. I doubt that there will be any condensation on the inner balls; the outer rows are an ideal design for blocking the vapor long enough for the board to heat up and stop condensation entirely. It takes some serious pressurized blasting to accomplish that.

The immersion in the boiling solvent+defluxer liquifies the flux on and under parts (we're talking rosin here, not water soluble) and removes most of it. The power spray with distilled solvent can then really sweep it clean. We use a hand wand for the spray and pay extra attention to things like CSPs and BGAs and anything that lies flat on the board.

The dirty/boiling tank is circulated through a filter and a tank that has some sort of flux-absorbing pellets, so there's not a lot of flux in the boiling tank. And of course, that tank and the filters and stuff are dumped and replaced regularly.

We have an optical video gadget that lets up peek under BGAs from the side, and see any flux or crud or flakey solder joints. The one we have works 3 or 4 balls deep, but we've ordered a better one with super optics to inspect deeper, as we're using bigger parts lately.

Here are some cool pics:

I'm still shocked that BGAs work as well as they do. We have only had one or possibly two BGA soldering problems so far, out of thousands of chips and millions of joints. This is orders of magnitude better than fine-pitch leaded parts.

No, the boards that were cruddy were soldered with water-soluble flux, so we figured that water would be best for washing. It was bad enough, The Brat getting soaked with water.

I knew some people who had an expensive IR absorption spectrometer. The only thing they ever used it for was to check the lab supply of ethanol, before a party, to make sure there was no benzine or whatever.

We've found the same thing. The last BGA I used at the PPoE had a .5mm pitch. Zero problems. Though the CPoE doesn't like

miso a écrit :

You mean drink it out of a glass, not out of the bottle?

Haw! Both Brat and party paragraphs are pretty funny.

Okay, well, I was kinda wondering if the water pic could actually pump the alcohol (I don't know why not, but....) and whether the alcohol would deteriorate internal parts (of the water pic; I know it would deteriorate mine).

Thanks.

Of course it depends what exactly is in that 0.1%. If it's water, that's okay.

Best regards, Spehro Pefhany

I have a cute little Pyrex beaker, my favorite rum-and-coke glass.

probably cheaper than the fake canned air (some sort of flourocarbon)

have you priced bottled nitrogen, bottled CO2 or other industrial inert gasses?

Does the vapor condense from above the PCB, and rain down? Then the heat of condensation must come from the vapor mixing with cold air.

I'm not interested in elitism, I'm interested in the thermodynamics of cleaning boards. Condensation heats things up, and vapor doesn't condense onto hot things.

Do you think the vapor will penetrate under something big and flat, like a BGA?

• Not so; i built such a vapor degreaser and used it many times; a PCB even when it gets heated by the vapor, is still cool enough for the vapor to "rain" continuously on the PCB.

• That distilling happens in even the crude degreaser I mentioned - and even after months of use and the bottom was gunky as all heck, the efficiency was amazing and seemed to not be reduced. That 100W heater was sufficient to boil the working fluid, and running cold water is a bit less expensive that a refrigeration unit. What you describe is obviously an industrial degreaser bought "off the shelf" and appears to be ideal. But my experience with my crude unit indicates that the implied elitism is misplaced.

That is another good way to go, BUT the ultrasonic tank required to hold reasonably-sized boards is rather expensive and most likely beyond what was originally asked for. That is why i offered a "home-brew" solution.

Gasp! .. .. You mean .. .. a PLURAL compound?

..and do not forget about compressor oil.

Badly burnt toast?

;-)

-- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)