Solder for Clean PCBs
« on: July 31, 2019, 10:53:27 AM »
I've been using Kester 44  forever and I really like the way it works. But it's flux messy and damn hard to clean. IPA doesn't do it.  Does anyone have a recommendation for a solder to use on new PCBs that will allow the flux to be cleaned fairly easily?

I know it's a cosmetic issue but I hate having new boards with crud on them. Seems unprofessional.  I'll probably still use 44 for repairs.


Khron

Re: Solder for Clean PCBs
« Reply #1 on: July 31, 2019, 11:04:00 AM »
I've been using Felder IsoCore RA leaded for the last few years, and it seems to have just the right amount of flux in it - enough to ensure a clean joint, but not so much that there's a pool of it left over. And IPA seems to do a good enough job of removing the leftovers.

https://www.felder.de/files/felder/pdf/EN_18-ISO-Core_RA_lead.pdf
Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

Re: Solder for Clean PCBs
« Reply #2 on: July 31, 2019, 11:22:35 AM »
I've been using Felder IsoCore RA leaded for the last few years, and it seems to have just the right amount of flux in it - enough to ensure a clean joint, but not so much that there's a pool of it left over. And IPA seems to do a good enough job of removing the leftovers.

https://www.felder.de/files/felder/pdf/EN_18-ISO-Core_RA_lead.pdf

 Thanks! Initial search shows that its a bit difficult to get in the US but I'm sure I can order it somewhere.

Any other suggestions?

Khron

Re: Solder for Clean PCBs
« Reply #3 on: July 31, 2019, 11:31:00 AM »
I've also used Stannol a bunch of years ago, but only 1mm thick (the Felder i've used up to this day was 0.5mm), so that obviously contains a bit more flux, but i don't recall that being particularly stubborn either.

Multicore is a US brand, i believe? If that's easier to get on what i assume is "the other side of the pond" :)
Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

Re: Solder for Clean PCBs
« Reply #4 on: July 31, 2019, 02:00:17 PM »
Anybody try Kester 331 organic core?  Has to be cleaned but washes away with warm water.

Matador

Re: Solder for Clean PCBs
« Reply #5 on: July 31, 2019, 05:10:41 PM »
Regular rosin flux can need nasty chemicals (like MEK) to dissolve completely.

Water soluble fluxes work well (especially if you like ultrasonic cleaning).  Kester 331 is a good choice, but remember that it *has* to be cleaned, because the flux is conductive.

Ricardus

Re: Solder for Clean PCBs
« Reply #6 on: July 31, 2019, 06:22:25 PM »
I just started using this stuff and really like it. Very little cleanup.

https://www.mouser.com/ProductDetail/910-SMD3SW.0318OZ
Audio mastering for hire..

Re: Solder for Clean PCBs
« Reply #7 on: July 31, 2019, 06:23:47 PM »
has to be cleaned is kind of annoying. I ordered some Kester 245...maybe it will be a bit better.

Oh nice, haven't come across the chipquik stuff. Seems like a good option since it no clean and water soluble. I might have to order a small roll.

john12ax7

Re: Solder for Clean PCBs
« Reply #8 on: July 31, 2019, 06:40:10 PM »
Kester 275 is no clean and doesn't leave a lot of visible residue.

Re: Solder for Clean PCBs
« Reply #9 on: July 31, 2019, 06:44:11 PM »
Kester 275 is no clean and doesn't leave a lot of visible residue.
I was trying to decide between 245 and 275. I couldn't really find much difference but I've never looked into solder much. I've just been using 44 since it works really well for repair.


Ricardus

Re: Solder for Clean PCBs
« Reply #10 on: July 31, 2019, 07:07:38 PM »

Oh nice, haven't come across the chipquik stuff. Seems like a good option since it no clean and water soluble. I might have to order a small roll.

It definitely flows a little differently than the classic old 60/40 stuff I had been using even though it has a slightly lower melting point. My dad must have bought a case of the 60/40 once upon a time because I had enough of that stuff to float a battleship.

Anyway, I needed to get some practice with it, but I really like it.
Audio mastering for hire..

Mylithra

Re: Solder for Clean PCBs
« Reply #11 on: August 08, 2019, 08:48:46 AM »
Ive been using the 245 for a few years now. Its eutectic, not 60/40. (At least the stuff I have is)
The no-clean core does leave behind this sticky flux residue but it does clean up easily with isopropyl alcohol and cleans up far easier than anything else I've used though I've not used that organic fluxed solder.


rp

Re: Solder for Clean PCBs
« Reply #12 on: March 24, 2021, 08:37:32 PM »
I'm bumping this thread because I'm in the exact same boat as the op. Wondering if anyone has experience comparing Kester 44 with 245 and 275 (and maybe 285) in practice?

I currently use Kester 44 in 63sn/37pb, which I like. But I agree with the op, the flux is hard to clean and I usually just leave it. I intend to stay with 63/37, and I'm curious if the other flux formulations are improvements over 44 or just different? Specifically regarding amount of residue left after soldering, cleanability, and ease of hand-soldering.

Ive been using the 245 for a few years now. Its eutectic, not 60/40. (At least the stuff I have is)
The no-clean core does leave behind this sticky flux residue but it does clean up easily with isopropyl alcohol and cleans up far easier than anything else I've used though I've not used that organic fluxed solder.
Kester 275 is no clean and doesn't leave a lot of visible residue.

Have either of you compared the 245 or 275 to the 44?


I ordered some Kester 245...maybe it will be a bit better.
I was trying to decide between 245 and 275. I couldn't really find much difference but I've never looked into solder much. I've just been using 44 since it works really well for repair.
What made you lean 245? Or did you end up staying with the 44?

Re: Solder for Clean PCBs
« Reply #13 on: March 24, 2021, 08:45:39 PM »
245 is great. Cleans up really well compared to 44. I will still use 44 when I’m having flow issues with old pcbs and molex pins.

For new pcbs I use 331 which is an organic core solder. It’s must clean but washes away with water. PCBs are amazing clean after a quick wash and scrub.

rp

Re: Solder for Clean PCBs
« Reply #14 on: March 24, 2021, 09:33:03 PM »
245 is great. Cleans up really well compared to 44. I will still use 44 when I’m having flow issues with old pcbs and molex pins.

For new pcbs I use 331 which is an organic core solder. It’s must clean but washes away with water. PCBs are amazing clean after a quick wash and scrub.
Cool! This is helpful, thanks for the reply. I think I'm leaning in the 245 direction. From what I can find, it seems like the 275 falls somewhere between 245 and 44.

I've come across the 331 as well in my searching. The requirement to clean it really thoroughly or else risk corrosion spooks me a little bit, but it's good to hear you like it. The ability to clean a new board well is appealing, so I might try that one a little down the road. The folks at the synth forum seem like it too.


 

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