Brake Cleaner used as a PCB Flux Cleaner

The usual safety disclaimers apply. Don't drink the stuff like some loopy folk do with hand sanitizer
( good one Mr President), don't inhale (didn't a past President make some claim concerning pot?) and watch the naked flames. It's your shack, your health and your life. Take it seriously because it is totally your responsibility.

In my ham projects it's ok to take shortcuts. You should never try this on a commercial product you sell. You have been warned!

I haven't been satisfied with methylated spirits as a flux cleaner for some time. And isopropyl alcohol is expensive and not that effective in my experience. I was ready buy proper flux cleaner like that I use in my own business but somewhere in my internet browsing I came across reference to using brake cleaner as a flux cleaner. Never shy of testing such claims I thought I'd give it a whirl.

Dropping into the helpful people at Repco, and being up-sold by and extra $1.20 to their premium brake cleaner costing $8.29, I came home and trialed the brake cleaner.

 

Even on my personal projects I'd only use this in a pinch. But it works out to be substantially cheaper than proper flux cleaner and is readily available. Not too many of us have an electronics outlet on our doorstep open on a weekend.  But the long term consequences on the board are unknown and it leaves more of a film on the board surface than proper flux cleaner. Other brands might be different though.

I devised a test for three flux residues :

1. Rosin from a homemade flux (rosin dissolved in methylated spirits and wiped on with a cotton wool tip or splashed on the solder reel and allowed to dry on the solder wire - why you would bother with the crap some Chinese sellers pass off as solder is beyond me, but it might make it usable)
2. residue from Multicore solder
3. the flux unused from a cheap syringe type product, again from China (works for me though)

Fluxes 1 and 3 are the result of trying to make that cheap solder flow nicely over the joint. Personally, I keep it on hand to give away to people to educate them on why saving cents can ruin your day. But enough China bashing for one day!

A quick test board was prepared using a rejected board I had to hand and is shown below:

 

The rosin flux and Mulitcore flux have proved difficult to remove in the past. The cheap eBay flux can be effective but is impossible to apply in small amounts so it is always messy.

Three brief spurts with the brake cleaner and I had this:

Rosin residue completely gone!

Multicore residue almost gone.

Cheap syringe flux partially gone.

I was starting to get excited now. A tiresome chore solved so easily. A quick dab of brake cleaner on a cotton wool bud rubbed on the remaining residues and the resulting board:

 

 

The soldermask did not appear to suffer and the result was a spotless board. 

 

In conclusion it appears brake cleaner does the job very well in the short term. The long term consequences are unknown and that needs to be considered. How comfortable are you that the construction effort today might not last?

 

73's

Richard