Liquid flux and a flux pen

old wrench

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Yesterday evening I did a direct comparison between paste flux and liquid flux applied with a flux pen

The tub of paste flux that I've used for years is a decent product from Radio Shack - it's what I've used on dozens of guitar wiring jobs and several amplifier builds - it's always worked well for me

But on my first pedal build, I found that it was kind of a pain to apply it to all those small components and especially to the small holes in the circuit board

So, I bought some liquid flux - Kester 186 and a Bonkote 102 flux pen with the small tip

I used the flux pen loaded with the liquid flux on a pedal circuit board last night

Much faster job of applying the flux and better soldering results too - better solder flow with noticeably less heating time

And a much cleaner job - I'm sold ;)

.
 

old wrench

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A little bit more info about flux and soldering

Although it's said that there is no need to clean up the Kester 186 flux residue after soldering because it's not corrosive - I do clean the board after soldering

The 186 flux I use cleans up very easily - it's actually the 186-18 version, which is 186-36 flux diluted to a 50% strength - which is still strong enough to get the full benefit of the fluxing action while at the same time ending up with just half the residue



This is the Kester 186-18 flux I'm using -


You can also get the flux already loaded up in a Bonkote 102 flux pen -


I don't have anything to do with that particular seller - it's just the best deal I was able to find



For clean up, I use a regular plumbers-type flux brush with the bristles trimmed back short - the shorter bristles make the brush a little stiffer

I use regular old de-natured alcohol to wet the brush and give the soldered pads a quick going over, it dissolves the flux residue very quickly

A little bit of blotting with a paper towel absorbs the flux and alcohol residue - and you are left with a nice clean populated and soldered board



I use the old electrical soldering stand-by, the same stuff the boo-teek builders use - Kester 60-40 solder -

.031" dia. solder and a very small chisel tip for the small components and small solder pads -

.050" dia. solder and a medium chisel tip for the larger components like pots and switches, also for amplifier and guitar wiring

I keep the soldering station set at 650 degrees F for all of it - I like using a relatively hot tip so I can quickly get the component lead and the pad up to temperature - solder it, and move on - less chance of damaging the board or lifting a pad from prolonged heat

The liquid flux really helps because of its wetting action and the way it helps the solder flow - get it hot quickly, flow the solder to make a solid joint, pull the heat away, and move on

You'll have nice, shiny, and solid electrical connections that won't fail ;)

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telemnemonics

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Interesting.
I dont doubt the better results but never had a problem using flux core solder.
New vol pot I put in an Esquire a few nights ago, no pre tinning or anything, just my Weller 100/140 gun and flux core solder.
The extra little hook of wire is because I tend to swap pickups often enough that a potgets messy if I repeatedly change wires on and off, so I solder the the hook.

Hard to solder stuff may need flux first, and maybe a lower wattage pencil iron goes faster with pre flux?
I'm impatient and stuck in my ways!

(I think I dug out a tube of flux to solder a Strat trem claw recently)


454C41E4-DFDF-44DD-AE73-27588BDA6E96.jpeg
 

owlexifry

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never had a problem using flux core solder.
same.
when i bought my cheapo 40W soldering iron (still using) when i started getting into this DIY game about 2 years ago or so, i was told that the solder contains a flux core and hence additional flux wasn't really necessary.

i do rarely use a flux gel (syringe), but only when soldering mini-switches or other scenarios where i need to minimize heat exposure as much as possible.

for vero/stripboard builds, even if i never use liquid (gel) flux, the board has to be cleaned with a PCB cleaner (aerosol can) regardless, because the flux residue from the solder flux core, gets everywhere.
(i never noticed how apparent this was until i actually used a PCB cleaner while troubleshooting a build)
 

telemnemonics

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same.
when i bought my cheapo 40W soldering iron (still using) when i started getting into this DIY game about 2 years ago or so, i was told that the solder contains a flux core and hence additional flux wasn't really necessary.

i do rarely use a flux gel (syringe), but only when soldering mini-switches or other scenarios where i need to minimize heat exposure as much as possible.

for vero/stripboard builds, even if i never use liquid (gel) flux, the board has to be cleaned with a PCB cleaner (aerosol can) regardless, because the flux residue from the solder flux core, gets everywhere.
(i never noticed how apparent this was until i actually used a PCB cleaner while troubleshooting a build)
True with stuff you shouldnt overheat and cannot protect with a heat sink, faster results.
 

RetiredUnit1

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yeah I've used the .031 flux core for all my builds for close to 25 years, never once have I had an unsuccessful solder..... I keep my wesd51 at 743f. My buddy Bob worked as a tech for Paramount studios, he said "the old man" of the place said it worked the best.

Now I'm the old man, lol. I use a fine tip. Bob had a master's too. Too bad he smoked so much tho, gone at 51 he was. Far too young.
 




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