Board Cleaning - Techniques - Chemical Reactions

[Trash80toHP_Mini]

Subject came up when mactjaap mentioned soaking a board in "cleaning vinegar' in attempts to revive his Macintosh ED DOVE enhanced. Naturally my curiosity about the science involved was piqued and a couple of things came to mind:

Dishwasher safe notions:

Vinegar it is acetic acid and water. So if the cap goo you're trying to remove is acidic, vinegar won't be the cleaning agent to do it. You need a base solution to deactivate acid. Wait until others chime in as to whether a baking soda solution would be harmful to electronics. There won't be enough acid to turn a board into a bottle rocket, but the carbon dioxide rocket exhaust ought to help in "blasting away" goo deposits under components.. [}] ]'>

edit: I've often wondered if running a dishwasher with baking soda as the "detergent" and then rinsing with a water only cycle might be the best way to clean cap goo from boards?

If rust is your problem the phosphoric acid in soldering flux might be your best bet. It's the active ingredient in naval jelly rust remover. I wonder if dissolving naval jelly in water will work?

Straight phosphoric acid is used as a food additive, so running it in a dishwasher as the detergent should be fine. Running the dishwasher with baking powder "detergent" afterward would clean it out nicely and make it smell fresh too!

Dishwasher options REJECTED!!!!!!!! by significant others.  [] ]'> Alternatives?

Take the dishwasher safe solutions outdoors: </punintentional>

 

A - If you've got a compressor, loading up a paint spray gun or detail gun to blast away with "enhanced" compressed air should work.

B - Airbrush setup might work if available.

C - Spray gun that uses a propellant can: Big Box availability

Critiques, additions, success stories and epic fail accounts requested. [] ]'>

 

[360alaska]

I put em in the dishwasher, sometimes twice with different sides facing down. Then I put em in my oven @ 170F for 4 hours.

 

[trag]

I will add, on the phosphoric acid idea, I do not know if that would be a good thing to try or not but if you want to try it, Home Depot sells a rust remover product in the paint section which is just a liquid phosphoric acid solution.   It's great on iron and steel products, where the solution will cause the formation of a tough, black coating which takes paint nicely and is resistant to further corrosion.  It's one of those kind of rectangular bottle (a few times longer than wide) and the solution is greenish and has a viscosity like water.

 

[Trash80toHP_Mini]

I'm thinking that you'd want to use a straight phosphoric acid solution in a paint spray gun to blast the (black stuff) iron phosphate off as it is converted from iron oxide. Dunno, just spitballing here.

Sounds like iron phosphate isn't something I'd want to try producing in a dishwasher. 8-o

 

[techknight]

Lemme explain something. 

I bought an ultrasonic setup for the Shop where I work, and it works miracles. Branson EC Cleaner, the more you add, the less time it takes to cavitate on clean. I am finding around 450 to 500ml per gallon and a half, for about 3 minutes at 60C temperatures. 

the more damaged the board, the longer it takes. In my case, I am using it to remove flux, finger prints, and solder/rework residue. Leaves the PCBs so clean you can eat off them. 

I am thinking about bringing a couple Cap goo'd boards in, and trying those out. 

 

[CelGen]

I just wash the boards with part of a broken dustpan broom or a toothbrush under hot running water and then blast the water off with the air compressor and put them out to dry for 24 hours. Screw vinegar and wasting expensive iso.

 

[Trash80toHP_Mini]

Is cap goo acidic?

 

[techknight]

I have never physically tested it, so I dont know. But it could be a strong base as well, Hard to say. Whatever it is, it eats the PCB I know that much. 

It also loves to get into the inner-layers of the PCB and screw with inter-trace capacitance, or trace-to-plane capacitance, this wrecks havok in circuitry that requires feedback/reference to work properly such as the Backlit portable. Nothing better than having a bunch of parasitic capacitors that you cant do anything about. YAAY. 

 

[Trash80toHP_Mini]

Anybody got cap goo and a litmus strip handy?

 

[Scott Squires]

Ultrasonic cleaning is definitely the way to go. Wish I could afford one large enough for logic boards!

 

[Scott Squires]

I did the litmus test a while back. I decided that vinegar was the appropriate opposite pH range, so the goo must have been alkaline. I only did one sample, so YMMV.

 

[Trash80toHP_Mini]

Ultrasonic's outta sight, but vinegar's cheap enough. I need to find my paint spray gun to do a test run with good ole H2O to see how a relatively gentle pressure  washing of a board will go.

Spraying outside using some kind of collapsible containment system will allow for recycling the vinegar:

clear plexi window

pair of heavy duty rubber gloves (the long ones)

big heavy duty trash bag

spare vinegar bottle lid

roll of duct tape

wardrobe type moving box

With a little ingenuity you've got a fold-up board blasting booth like this one for sandblasting from Harbor Freight:

No need for the door, a twist tie takes care of that, point one corner down for the spare cap (drilled out hole in "top") and you're all set. Cut the top of the box down and angled for the window and it'll be smaller than the wardrobe box started out when it's stored away.

Only drawback I can think of is that even after blast flushing it out with water, it'll probably still smell like a salad. :-/

But maybe my hands and arms won't be like they took a vinegar bath up to my elbows. The backyard/neighborhood shouldn't smell like on either. Can't imagine what my apartment neighbors or landlord might say if I blasted away with vinegar on my terrace.  [)] ]'>  Pressure washing with H2O in the same rig ought to work better than a dishwasher and not get anything thrown at you! [] ]'>