Solder for Clean PCBs

[RSRecords]

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]

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

 

[RSRecords]

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]

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"

 

[RSRecords]

Anybody try Kester 331 organic core?  Has to be cleaned but washes away with warm water.

 

[Matador]

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]

I just started using this stuff and really like it. Very little cleanup.

https://www.mouser.com/ProductDetail/910-SMD3SW.0318OZ

 

[RSRecords]

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]

Kester 275 is no clean and doesn't leave a lot of visible residue.

 

[RSRecords]

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]

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.

 

[Mylithra]

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]

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?

 

[RSRecords]

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]

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.

 

[jokeramik]

Please use Kontakt LR.

Best regards!

jokeramik

 

[Jeff Goodman2]

Many years ago, Saul Walker and I went through the water soluble flux experiment. The cleaned circuit boards looked great, nice and shiny, but...as time went by we found that the rosin is not only weakly conductive, but also corrosive to other materials in the components, if not completely removed. We could not find a consistant way to completely remove it.

Things might have gotten better at this point, we stopped using it and I have never tried it since. This was probably 20 years ago, so as I said it might have gotten better.

Jeff

 

[JohnRoberts]

Many years ago, Sol Walker and I went through the water soluble flux experiment. The cleaned circuit boards looked great, nice and shiny, but...as time went by we found that the rosin is not only weakly conductive, but also corrosive to other materials in the components, if not completely removed. We could not find a consistant way to completely remove it.

Things might have gotten better at this point, we stopped using it and I have never tried it since. This was probably 20 years ago, so as I said it might have gotten better.

Jeff

+1....  water soluble (organic) flux can be a reliability disaster if any residue is left on the PCB. We ended up with massive field service problems from one production run of Loft delay line boards. On top of that my business partner tried to clean the boards better using a high pressure air hose, and ended up forcing moisture inside some of my favorite dielectric polystyrene filter caps, trashing them. 

Properly done the organic flux may work for large scale production with rigorous machine water wash, but small volume operations with questionable cleaning can be problematic. 

JR

 

[Whoops]

I use this product to clean the PCBs after soldering,
it works great and the PCBs get totally clean

 

[fragletrollet]

When I was just starting out, I got some soldering gear from the local hobby shop. I picked up some generic 60/40 solder, but soon changed over to Stannol HS10, a random pick (mostly due to it being 0.5mm) from a daunting list of cryptic specifications at my chosen online vendor. After restocking on the only solder I had good experience with, I have now run out. As far as I understand, solders containg lead are now banned (?) from sale, at least in my country (Norway) and I guess EU or most of europe.
Anyhoo, all solders seem to be exchanged with Tin(Sn) dominant mixes, with the choice of a pinch of copper or nickel added.
I just got some more 60/40 from a brand called Cynel, however this instantly reminds me of the first 60/40 I used; higher melting point, much worse wetting and flow of solder, sticky nasty residue that is hard to clean off.

How are these lead free solders? Should one stock up on one's favorite leaded type while it's still "available" from less health-concerned markets? Any recommendations on something I'd get from say Reichelt would be appreciated, as they don't stock pb solder like US vendors still do?

I'm guessing this should be comparable to my old favourite (flux wise atleast):

HS10 Sn99Cu1

or this one, supposedly clearer residue (mind me I would rather have residue that is easily washable)

Crystal 511