New to Soldering

Discussion in 'FAQs' started by jpohl, Jan 2, 2004.

  1. jpohl

    jpohl New Member

    I was at Radio Shack today to get a solder iron. Got a duel wattage 20/40 based on some posts I have read, along with a base with sponge and holder.

    I bought two things of Rosin-Core Solder in a spool. One is .050 diameter and has a fraction of 60/40? The other is .022 Dia Silver-Bearing Solder and a fraction of 62/36/2? What do those fractions mean? The larger diameter states it is for "PC Work" and the smaller diameter is for "High-Tech - Rosin-Core".

    I looked all over the shelves for Flux and could not find any? I am not really sure what flux is either or what it does. The guy at Radio Shack said All I need is the iron and the Rosin-Core Solder I bought? Can someone please explain what flux is?

    I am planning on soldering wire to my Digitrax PM42 Power Monitor and also soldering rail joints on my N-Guage layout I am just starting on.


  2. Arlaghan

    Arlaghan Member

    Flux is a substance (liquid or paste) that you apply to the surface prior to soldering. It's purpose is twofold: to transfer heat to your subject and also to clean it of impurities. I recommend getting some. I got a little tub in the hobby section at Home Depot.
  3. ezdays

    ezdays Out AZ way


    Welcome to The Gauge. Solder comes in different diameters and different metal compositions. 60/40 is the tin/lead % content, .050 is the diameter in inches. The "silver-bearing" solder contains a % of silver, in your case, only 2%. .022 is very fine and hard to work with, the silver content makes it harder and requires a higher temperature to melt. We used .031 60/40 for our electronic assembly work, and I still have some that I use. but 050 is OK for what you are doing. The rosin core is the flux, used to clean the surface so that the solder will flow onto the surface being soldered. It is a good idea to clean the surface first with a light sanding or wire brushing. If the surface isn't hot enough or clean enough you will get what is referred to as a "cold solder joint" where the solder just balls up but doesn't flow.

    It is a good idea to have some liquid flux in addition to what is in the solder, you will be surprised how much easier it is to solder and how much better the results are. Be sure the flux is either water-soluable or rosin, DO NOT USE ACID CORE SOLDER OR ACID FLUX ON ELECTRONICS. It will corrode the joints very quickly. If your Radio Shack store doesn't have liquid flux, you sould be able to find it at another electronic supply store or they can order it for you. You don't need much, a pint bottle should last you for years (assuming you don't spill any.:D )

    I hope this helps you.

  4. Russ Bellinis

    Russ Bellinis Active Member

    You can get the water based paste flux from any Sears, Home Depot, or other hardware store in the plumbing department. Just make sure you clean all parts to be soldered very well.
  5. ezdays

    ezdays Out AZ way

    Yeah, you guys are right, I've got so much liquid flux left over from the business that I forgot about paste flux. still, the liquid is easier to apply. Water soluable is the best because it is a lot easier to clean up after soldering. A stiff brush dipped in water works fine. With rosin flux you need some solvent cleaner like acetone to clean the finished joint, a necessary step...

  6. jon-monon

    jon-monon Active Member

    Not a bad idea to have flux on-hand for soldering old stuff, but if everything is clean, the flux in the core of the solder should be all you need.

    Practice makes perfect, stick to it until you are osldering well. It's a valuable skill. I suggest starting with some small copper wire and/or thin copper sheet to practice with.
  7. jim currie

    jim currie Active Member

    one thing that was always stressed to me was before you solder a good mechanical joint is required.
    also welcome to the gauge:D
  8. jon-monon

    jon-monon Active Member

    This stuff is a great product for cleaning soldering irons. It comes in a small tin, maybe 1" dia., and lasts a long, long tine. Weird stuff, looks porus, feels dry, melts when used. EMF carries it, I'm sure other electronics tools suppliers.

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  9. boppa

    boppa Member


    dont use acid flux
    the plumbers stuff

    i dont know how many times ive had to fix things up because `a mate' told them to make sure its well fluxed

    well after putting any plumbers flux on
    it well and truly........

    well fluxed

    unless you are 100% sure its usable on electronics (non acidic)
    DONT use it

    clean with a brightclothe(a scouring pad but NOT steel wool-the green plastic type) until metal shiny
    tin(tinning is precoating a bare metal surface with solder)
    once the track (or other metal) tinned, solder wire to it

    btw i see a lot of people here using 20-40w irons
    cheap-and nasty
    for soldering a nickel track
    i use a super scope
    150w temp controlled

    i dont even use a 20w for soldering a plug on stereo headphones

    ( a big iron can do a good solder joint with a quick touch and go on a small [hehe edit big out] job, a small iron CANT do a good solder joint on a big job no matter what you do)

    just my personal opinion (backed up by literally 100's of 1000's of soldering joints as an electronics tech and an auto electrician and of course a toottooter :) )
  10. jon-monon

    jon-monon Active Member

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