I want to get a Kester Flux Pen but I don’t know which one. Kester has about 5 different kinds. I will be doing general SMD rework on PCBs. I would prefer not to have to clean up afterwards. I am using Kester 60/40 .025" rosin core solder. I am not sure whether to get the 186 Flux Pen or the 951 Flux Pen.
I’ve personally had a lot more success with paste flux for SMT stuff instead of liquid flux from a pen or bottle. I just find it easier to work with since it can help keep pieces in place on the board, and it’s not much harder to only put it where you need it with a syringe applicator. Before I got some, I used #186 and it will get the job done.
No-clean is kind of overrated in my opinion. You still have to clean it off the board if you want to make it look professional (residue offends my royal eye LOL).
If your solder has rosin flux in it, then you have to clean the board anyway.
Applekid:
No-clean is kind of overrated in my opinion. You still have to clean it off the board if you want to make it look professional.
Yeah, I have to agree. They can only claim it “no clean” because the residue left over has a translucent appearance to it. It still leaves behind a mess and in my opinion, still looks just as bad as your typical brownish rosin types of fluxes. Leaving that on the board is just a sign of poor work and laziness (if you want my HONEST opinion :mrgreen:)
Applekid, what brand of paste do you have that comes in a nice syringe like that?
Applekid, macegr, and rpcelectronics, how do I clean off the rosin flux residue if I decide that I want to clean it off? It is crusty and looks caramel in color. Please give the brand name and exact product of whatever you recommend so I can buy it.
Thank you for your help guys.
piglet:
Applekid, what brand of paste do you have that comes in a nice syringe like that?
I find most do. I got one that came with the [ChipQuik starter pack, and I liked it enough that I bought another flux from [MG Chemicals so I can keep the ChipQuik stuff all together in case there’s some weird chemistry I don’t understand about mixing different types for use with the ChipQuik system (sounds very “wave a dead-chicken” but I’d rather be superstitious than have a bunch of bad boards).
Yes, these are “no-clean” fluxes, so, even though choose to clean them for looks, I like that I have the option to be lazy and it won’t affect the project itself. 
piglet:
how do I clean off the rosin flux residue if I decide that I want to clean it off? It is crusty and looks caramel in color. Please give the brand name and exact product of whatever you recommend so I can buy it.
I’ve used high-purity isopropanol also from MG Chemicals along with a stiff-bristled brush with so-so results cleaning up rosin residue. The stuff absorbs water so it definitely has a shelf life before it becomes less pure (and less effective). It takes a little more elbow grease than I’d like to use. After spraying and scrubbing with the brush I would remove with coffee filters since they’re lint-free, so long as you’re careful and don’t tear them on any soldered through-hole components. For tight spots I use Q-tips, but they’re really a desperation move on my part since they can leave real annoying cotton fibers everywhere.
Lately I’ve been using a dedicated flux removing pen from [Chemtronics and I like that I can do the scrubbing work with the pen tip itself, followed with the coffee filter to wipe.
In either case, I find the sooner I try to clean the residue, the easier it is to remove. I don’t like to stop soldering to clean, but, it’s a balance.
Of note, I really haven’t been doing this for long enough to have a real preference. I picked these particular brands based on what was in-stock and that I had to pick ONE and couldn’t really find recommendations either way, so there may be cheaper and better options out there. :?](Findchips: CW9400 Price and Stock Results)](Findchips: 8341-10ML Price and Stock Results)](Findchips: SMD1 Price and Stock Results)
I use a dedicated spray from Asalco. I have not done any back to back tests in any way with it and it states that it is for cleaning boards shortly after they have been soldered, so not for hard dried flux.