Cleaning Agent when soldering

One trick with removing a component on a PCB is to re-solder it first. During manufacture the flux will have been washed off and so when again applying a soldering iron the old solder is reluctant to flow. Re-soldering applies new flux.

These days applying a liquid or paste flux is equally effective.

When cleaning up component holes on PCBs a de-soldering braid is useful. This braid is loaded with flux but in my experience it works better if you add a bit more.

Reply to
alan_m
Loading thread data ...

I use flux cleaner!

Reply to
Bob Eager

In the UK it used to be sold with the purple dye methylene violet in and a trace of pyridine to make it unpalatable. A bittering agent is also used to make it harder for people to distil it to pure potable ethanol.

formatting link
I think the purple dye may also have been substituted as it is mutagenic. I've seen nearly blue meths on sale in the sheds.

Reply to
Martin Brown

I thought acetone was a component of 'flux off' products, but now I look that up ('Chemtronix Flux-Off Rosin' spray):

2-methylpentane (containing < 5 % n-hexane (203-777-6)): 25-50% 3-methylpentane: 10-25% ethanol: 10-25% 2,2-dimethylbutane: <10% 2,3-dimethylbutane: <10% propan-2-ol: <10% n-hexane: <1%

so just a soup of methylated hydrocarbons.

Theo

Reply to
Theo

The 2 litre bottle I have is very purple. It says that the colour may fade over time, but doesn't say what the colourant is. These days, I use isopropanol where I once would have used clear industrial meths.

Reply to
Colin Bignell

I used to have a de-soldering tool, which had a spring-loaded piston to suck the solder out of the holes. I could never get on with de-soldering braid.

Reply to
Colin Bignell

Braid is excellent for surface mount stuff, but you must flux it first. Either standalone flux liquid or a dab of flux-cored solder with the iron to get it going.

The desoldering plunger pump tools are ok for through hole components, where you get more of a blob of solder (the braid will tend to leave a fillet of solder in the hole that prevents the leg from moving), but not much good for surface mount (where there isn't enough solder for the pump to 'grab').

Often the trick with desoldering is to add *more* solder, because it makes for a bigger blob to suck and better heat transfer to melt what's there (then the pump/braid can soak it all up).

Theo

Reply to
Theo

Visa-versa for me I had both a solder sucker and braid and for most jobs braid worked better for me. The braid had to be fairly fresh and not been hanging around for years.

Reply to
alan_m

I think surface mount had just about been invented when I was working on PCBs, but it was rare and more for commercial use than the DIY circuit builder.

Reply to
Colin Bignell

The small bottle I bought many years ago and kept under the stairs in complete darkness has lost all its original purple colour and is now straw coloured.

Reply to
Andrew

Gentian violet iirc, aka crystal violet. Cheap because it's such a strong dye, but lousy lightfastness.

Reply to
Animal

Extraflex is a lot cheaper than braid, scrap co-ax even cheaper. The pvc usually keeps the copper bright, hich is what's needed for desoldering.

Reply to
Animal

What are you actually soldering though? Brian

Reply to
Brian Gaff

With the braid method you want to keep the soldering iron on the PCB for the shortest of time possible to prevent overheating and lifting tracks. I'm sure that extraflex and the much larger heat-sink properties of scrap coax braiding would be on sale for this purpose if they were more efficient. The desolder braid needs just enough surface area to heat up fast from the tip of a soldering iron and have enough wire to efficiently wick up all the solder on the board.

With scrap coax - assuming readily available aerial/satellite down-lead i) you have the hassle of first extracting the braid from the rest of the cable. ii) its too bulky to get into small areas iii) its too bulky to heat fast iv) it has to be a good quality cable - the braid in some coax is extremely sparse. v) once removed the braid is probably not woven tight enough to wick up the solder to the extent of the braid specifically designed for the purpose.

I'm sure that I will stick to the more expensive desoldering braid and some liquid/paste flux.

Reply to
alan_m

Soldering what?

Electronic stuff nothing - unless obviously dirty.

With copper tube, clean with abrasive strip and use a decent flux. Which applies to most things.

Reply to
Dave Plowman (News

I can only conclude you've never tried it as just about everything you said there is not correct. I can go into more detail if you want.

Reply to
Animal

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.