The inevitable flux question

[Onwar Hoh]

Just getting into electronics soldering. There seems to be a lot of varying opinions on what flux, when to use or if to use, etc.  Some fluxes are said to produce corrosion. Some say clean it up with Iso Achohol, others don't mention cleaning at all.

**My immediate purposes will be for minor repairs to laptop charging jacks and such.

Other than that, I'll be practicing on old circuit boards from old, broken or unwanted devices and can see myself diving in as I learn more.

I am starting off with the Hakko FX888D-23BY, which came with various tips, conical to chisel.

I just bought a 1lb spool of Kester 44 RC 63/37 .031.

I also wonder about the voracity of those who claim that merely mixing rosin with Iso (and a bit of glycerine for stability) is the best solution (i.e., good adhesion, low fumes...).

I do have experience with other forms of 'hot joins' in the form of arc welding (Lincoln Welder), brazing, silver soldering using acytelyn & oxygen, MAP gas, etc.

Any other beginner's advice also appreciated. For instance, type of work surface, tip cleaning compound (mix of flux and??) etc.

Thanks!

[LektroiD]

I used to use water soluble flux, but it is such a pain in the proverbials to clean off, and still doesn't remove all traces. I've built oscillators that have suffered tuning issues due to traces of conductive flux, so I go with No-Clean now, & as I always have, 60/40 solder.

[Onwar Hoh]

I used to use water soluble flux, but it is such a pain in the proverbials to clean off, and still doesn't remove all traces. I've built oscillators that have suffered tuning issues due to traces of conductive flux, so I go with No-Clean now, & as I always have, 60/40 solder.

Thanks for your reply. Helpful, as I need a flux that won't hinder the learning process (i.e., prevent good joints). After seeing the 'Dave Jones' you tube video, I see he recommends the Electrolube pen, but no details, and it doesn't seem to be widely available in the U.S.. But with the Kester I mention, is flux really necessary for the repairs I will initially be applying myself to?

[Yago]

Rosin core flux, flux gel and flux pen.
It is a low cost commodity, but there are times it can move your biggest stress!

Dunno about the pen, might be a country thing. (IE where are you, fill in country field of profile)

[Onwar Hoh]

Rosin core flux, flux gel and flux pen.

Hi. In reviewing my OP, I see that I neglected to be specific. The information I think I need is:

1. a flux pen and/or gel recommendation for my presently limited purposes (skill honing and simple {non-corrosion-producing} solder repairs on laptops and such).

Amazon U.S. offers this:

http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=flux%20pen&sprefix=flux+pe%2Caps

2. Best practices regarding use and cleanup.

[Yago]

Gel is Amtech NC-559-AS-TF, rosin based no clean gel 30CC syringe.
http://www.amtechsolder.com/tacky.html
Pen is Chemtronics:
https://www.chemtronics.com/p-701-circuitworks-lead-free-flux-dispensing-pen.aspx

Those are both USA products so should be available.
Note I am careful where I buy from as there are a lot of fakes out there.
Also, I use the pen only for similar rework on lead free products, it is one of the more aggressive fluxes, but prefer to stay with rosin-only for as much work as I can.


IPA (Isopropyl Alcohol) for cleaning, use an antistatic brush and scrub, then dab away the bulk with paper, last rinse and stand to dry.

[AG6QR]

If you're using a good name brand rosin core solder, and if your board and parts start out clean and relatively untarnished/unoxidized, then it should be rare to need any additional flux beyond what's already in the solder.  Rosin is the default flux for most prototyping and repair work, because it normally doesn't require cleaning.

Avoid any "water clean" or any other acid based flux unless you understand the process for cleaning the flux afterward.  It may be easier to clean than rosin, but an acid flux will destroy a circuit in short order if it's not cleaned perfectly, while rosin flux is relatively harmless on most circuits.

Personally, I rarely find a need to use any flux beyond that contained in rosin core solder.  But I'll occasionally brush on some rosin flux from Radio Shack, and I have used a flux pen containing rosin flux a couple of times.  I'll note that I still use leaded solder -- my flux practices might change if I used lots of lead-free.

I rarely clean rosin flux.  I'm feeling particularly energetic and want a beautiful board, I may use alcohol and a brush, but usually I just leave rosin flux there.  I have boards that are decades old, and they're showing no signs of harm from rosin flux.

[GreyWoolfe]

I have not tried any gel fluxes but I use MG Chemicals liquid rosin flux.  Depending on the soldering, I use either a small squeeze bottle or a hypodermic needle for precise placement of very small amounts.  I always flux-you can have too much solder but never too much flux.  I clean up the excess with small alcohol swabs.

[mariush]

I use a Polish made no-clean flux that comes in a small bottle and some quality Multicore 63/37 solder. For simple jobs, the no-clean flux inside the solder works well enough, for some bigger jobs I sometimes add a drop of flux.

[Fsck]

pretty sure everyone has their tastes.

I use kester 951 no-clean myself. (I also use kester 44 solder like you) I prefer pens myself, needle tips just seem to be too unwieldy with my shaking hands.

the only thing we're all likely to agree on for beginners is to avoid water-soluble fluxes which need to be washed off and obviously the plumber-oriented acid-based fluxes.

[LektroiD]

I use Ecowave 45, and a small needle dispenser bottle. I find these small dispensers very handy and accurate.

[nanofrog]

Kester 44 solder's flux core takes care of most things for me.

When I need extra though, I prefer Kester 186, or better yet, 186-18 (RMA & RMA low solids respectively). Unfortunately, it's only available in 1gal. bottles as the smallest size, so it's not exactly hobbyist friendly. A good alternative is MG Chemical's Rosin 835 (they offer 125ml and 1L containers). Particularly useful for drag soldering and tinning wire.

I dispense with either a needle bottle or a refillable brush pen (Bonkote BON-102). Lots of ways to do it though, and as mentioned, personal preferences will vary.