Hi everybody,

I've tried my new 22 [L] ultrasonic cleaner some days ago with 4x dirty PCBs, especially stained by rosin from welding wire.

First try : only deionized water, no heating, ultrasonic vibrations during 5 [min]. No result
Second try : only deionized water, heating at 40 [°C], ultrasonic vibrations during 10 [min]. No result
Third try : 3/4 deionized water and 1/4 isopropyl alcohol, heating at 50 [°C], ultrasonic vibrations during 15 [min]. A small result.

The attached user manual is a little bit skinny, and poor in images.

Just one thing : these 4x electronic boards have been soldered a "long time ago", in January 2018. Does this parameter matter ?

Sorry, no pictures available, because my smartphone's camera is out of order. Could someone help me ?

Joël

 

For rosin flux that's basically dried out you will need more time. I suggest leaving them immersed in ethanol for a week. Then try your ultrasonic cleaner to remove any residue.

 

This is the major component in rosin flux:


It is soluble in absolute alcohols, but a little water decreases that solubility a lot. You could try household ammonia and your alcohol mixtures, but I suggest just trying dish detergent in water first. A 3:1 mixture of water and isopropyl alcohol is not much better than water alone.

 

Try Liquinox.

 

Try Liquinox.

Interesting, made by Alconox. The old Alconox (circa 1960's) would clean our dirtiest glassware, particularly at 60 to 80°C. If it failed, the only alternative was dichromate in sulfuric acid. I have kept some of the old stuff for all these years, but haven't needed it.

 

Hi everybody,

I've tried my new 22 [L] ultrasonic cleaner some days ago with 4x dirty PCBs, especially stained by rosin from welding wire.

First try : only deionized water, no heating, ultrasonic vibrations during 5 [min]. No result
Second try : only deionized water, heating at 40 [°C], ultrasonic vibrations during 10 [min]. No result
Third try : 3/4 deionized water and 1/4 isopropyl alcohol, heating at 50 [°C], ultrasonic vibrations during 15 [min]. A small result.

The attached user manual is a little bit skinny, and poor in images.

Just one thing : these 4x electronic boards have been soldered a "long time ago", in January 2018. Does this parameter matter ?

Sorry, no pictures available, because my smartphone's camera is out of order. Could someone help me ?

Joël

Try rubbing alcohol and a toothbrush. Test on small section first.

 

Interesting, made by Alconox. The old Alconox (circa 1960's) would clean our dirtiest glassware, particularly at 60 to 80°C. If it failed, the only alternative was dichromate in sulfuric acid. I have kept some of the old stuff for all these years, but haven't needed it.

I used to use Liquinox for boards requiring ultra low surface leakage current. Liquinox in hot DI ultrasound wash, hot DI rinse, vacuum oven dry. Worked like a charm.

 

Tide and time worked for me.

 

Thank you everyone for your help, ideas, practice. I'll try different solutions and give you news soon !

 

It's been 4 days that my circuits are bathed in 99 [%] pure alcohol. No more traces of rosin flux ! I am happy !

I would like to try now my ultrasonic cleaner during 10 [min] with only 99 [%] pure alcohol to finish washing ? The device will not be damaged ?

Joël