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| Strange effect after ultrasonic cleaning pcb |
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| duzycinek:
Hello, I got question about using ultrasonic cleaner to clean pcb after soldering. When I clean pcb soldered with Mechanic XGSP80 Sn63/Pb37 solder paste, effect was really good, but after I placed it in ultrasonic cleaner with: 50 Celcius, 15 min, distilled water with flux cleaning solution for PCB, solder joints became dark gray. On other boards soldered in factory, solder joins did not change colour. When im scratching joints, they are normal inside, but PCB looks very strange becouse of this joints colour. Anyone know what cause this problem? |
| tomud:
--- Quote from: duzycinek on August 19, 2023, 07:51:58 am ---Hello, I got question about using ultrasonic cleaner to clean pcb after soldering. When I clean pcb soldered with Mechanic XGSP80 Sn63/Pb37 solder paste, effect was really good, but after I placed it in ultrasonic cleaner with: 50 Celcius, 15 min, distilled water with flux cleaning solution for PCB, solder joints became dark gray. On other boards soldered in factory, solder joins did not change colour. When im scratching joints, they are normal inside, but PCB looks very strange becouse of this joints colour. Anyone know what cause this problem? --- End quote --- Cleaning agents should be matched to the fluxes used during soldering. Here it is not easy and when the wrong preparations are selected, various tarnishes may appear on the solder and on the PCB itself. However, I am unable to answer whether the deposits (chemical compounds formed in the reaction of the solder alloy with the cleaning agent) have any negative impact in your case. Here it is best to consult the manufacturer of the preparation used to clean the PCB. Unfortunately, water-soluble formulations are not suitable for all solders and fluxes. In my experience, pure isopropyl alcohol (IPA) is the most neutral. Though it's not perfect either. |
| DavidAlfa:
Degreasers use to have caustic agents that will cause this. Probably it's made for rohs and it's attacking the lead. Also expect Mechanic solder to be absolute junk. I used IPA and the result was great, of course be careful, as this could cause explosive vapours. |
| robert.rozee:
in the past, after ultrasonic cleaning, i've rinsed PCBs in mentholated spirits (purple coloured) then brushed clean with a paintbrush. the final effect is a thin gloss, as meths (in new zealand at least) has a small wax component. this was for short runs of boards, and there was no RF or other analog stuff involved. a safer approach may be the same, but using IPA instead of meths. (written before DavidAlfa's post mentioning IPA) cheers, rob :-) |
| tomud:
The preparation available in Poland under the name (KT-5) is also suitable for manual cleaning. It doesn't smear flux like IPA, IMHO it's one of the better cleaners out there. I'm not 100% sure but most likely it's turpentine. Below is a photo of the bottle with this preparation... |
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