Solder for Clean PCBs

[Whoops]

What exact chemical is approved to remove 44 flux residue?

This is great for that:

 

[Fairman]

I have manufactured for more than 25 years some high-quality studio mastering tube gear and other HI-Q handmade gear using the Multicore / Loctite 362-SN62/52. It is an alloy, 62, 36, 2 Sn, Pb, Ag, Tin- Lead and silver with Rosin Flus. After the ("hysteric") RHOS invasion years ago I have tried many alternatives but got now about 10+ different dusty unusable roles in stock. In a hurry I then have ordered five/250G rolls from Farnel in afraid they will soon disappear, now luckily, after years still available until still "stock exhaust". It solders with the smoothest flow and glossy finish for many years, far away from whatsoever of the RHOS types. It leaves flux indeed and evaporates some steam as any other solder. I never had a needed of cleaning the flux in “normal” LF circuits. As I am soldering every day, I could not dream of not using my (professional) de-suggestion.

Now I am doing tube microphones with extremely high impedance circuits, incorporated resistors 50G to 1G ohm. Therefore, I carefully clean all soldering’s with Acetone and cotton swaps, patiently, but with excellent result.

 

[HP200CD]

What exact chemical is approved to remove 44 flux residue? The datasheeet for Kester 44 describes a "saponifier" but doesn't recommend any particular one.

I have been using acetone and it seems to work well, however it's a crap shoot as to whether or not it will damage the silkscreen.

Hi Matador,

A saponifier would be a soap based product. Something with lye to cut the organic resin in 44 type flux, as opposed to a detergent.

I get good results with 99% pure alcohol in a wash bottle. Might take several squirts because it dries very quickly. Also takes more scrubbing than other more aggressive solvents, but it is nowhere near as harmful to the humans in the room as MEK. Some people even like the alcohol fumes.

P.S. Many thanks for providing the world with your C12 PCB. Lots of beautiful tracks made with it here.

 

[kato]

Why is that?

Cleaned PCB's look pretty good to me, better than the looks of pcbs with flux residue all over the joints

If it's not necessary, like in the high impedance zone of a microphone PCB, then it strikes me as for aesthetics only, which seems like a poor use of one's time.

 

[mkjekyll]

I have manufactured for more than 25 years some high-quality studio mastering tube gear and other HI-Q handmade gear using the Multicore / Loctite 362-SN62/52. It is an alloy, 62, 36, 2 Sn, Pb, Ag, Tin- Lead and silver with Rosin Flus. After the ("hysteric") RHOS invasion years ago I have tried many alternatives but got now about 10+ different dusty unusable roles in stock. In a hurry I then have ordered five/250G rolls from Farnel in afraid they will soon disappear, now luckily, after years still available until still "stock exhaust". It solders with the smoothest flow and glossy finish for many years, far away from whatsoever of the RHOS types. It leaves flux indeed and evaporates some steam as any other solder. I never had a needed of cleaning the flux in “normal” LF circuits. As I am soldering every day, I could not dream of not using my (professional) de-suggestion.

Now I am doing tube microphones with extremely high impedance circuits, incorporated resistors 50G to 1G ohm. Therefore, I carefully clean all soldering’s with Acetone and cotton swaps, patiently, but with excellent result.

Thanks Fairman, been looking for something as alternative to WBT 0800 which is excellent but unaffordable. Is that alloy eutectic? Sadly the RHOS cert builds of all off the shelf gear are no longer reliable, seems every few years have to use a SMD rework air gun on the PCB's. Guitar amps are notorious for this as anything with heat cycling really does not stand up to normal use anymore. Seems we are over civilizing ourselves out of existence. In the 80s they had something called Grecian Formula to get rid of grey hair, the active ingredient was lead acetate, perhaps removing this made sense but not lead from solder. I was looking at some very pricey aerospace solder containing indium that was lead free, any experience with indium alloy solders? I reserve the right to use so called hazardous substances that the EU deems inappropriate.

 

[calaverasgrande]

Have you compared the K100LD to any of the other 275 solders? I've been using the silver version, but curious how the Cu versions compare.

I haven't tried other versions yet. I'm a hobbyist that does repairs for friends sometimes. So I'm only doing about 2 or 3 things a week either repairing old or building some new PCB up.
Takes a long time to get through a regular spool of solder that way!
I do have silver bearing and plain old Kester 77 on hand for repairs.
Not sure of the science behind it but the chief engineer when I worked in broadcast was vehement about not mixing solder types. He also had this terrifying way of speaking extremely calmly when he was pissed at people for not doing their job according to SOP. Imagine Mr Rogers crossed with POW camp colnel.
So I still don't.

Gotta say, it seems a lot of the animus towards lead free seems to be inertia. Our eyes and hands get used to solder behaving a certain way.
Hear a lot about whiskers. But from my understanding that is more a problem with avionics. Ordinary gear shouldn't experience such wide temperature gradients. Or be doing joins of different metals. We are using copper wire still right?