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soldering circuit board

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Newbie level 5
Apr 7, 2015
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Hi All,

Whenever I am doing soldering , I make a big mess of it . . I have seen lots of videos that show how to do it and it is normally done by putting the solder tip on the wire or board and then quickly put the rosin on it .

Does the watt of the solder make a significant difference ? Is the rosin another important factor ? do you have different rosin for different material ?

Do I need a bench solder?

I am trying to do some circuit board soldering :)


I'm worried that you mention rosin AND solder.

Get hold of a thin (0.5mm to 1mm) solder with the flux (rosin) already in it. That ensures the flux and solder are delivered at the same time and same place. If you must use a different flux, use electronics grade rosin (a thin liquid) and not plumbing rosin (paste) which is acidic and very corrosive and always apply it before the solder. It's purpose is to break down oxides that would stop the solder flowing so putting it an afterwards is pointless.

The soldering iron size depends on what you are making connection to, I prefer thermostatic controlled ones with around 50W rating for general purpose component soldering but they are quite expensive. A 'pencil' iron rated at 25W is perfectly adequate for most jobs.


Even among the electronic grade rosins, some are acidic and need to be washed away with water. You can't use these for wires, because they'll wick up into the wire and cause corrosion. Others can be left in place or washed away with alcohol. These can be used on wires and parts that can't be washed. There's a lot of different fluxes out there from different manufacturers and/or different scenarios.

Apply the flux first, then the soldering tip, then the wire solder. Generally, you want to apply the tip to the board and component at the same time to heat both up. If one part is a much more massive heat sink than the other, you may need to heat that part up first, so you don't melt the smaller part.

If you are joining wires, tin both ends separately. I normally don't add extra flux to wires, other than what is in the wire solder. If it's an old corroded wire, you might need to add some flux. Once both ends are tinned, use three hands (j/k) to hold the wires adjacent, then heat them up with the soldering iron together. When the the solder melts together, remove the iron and continue to hold them together until the solder hardens.

With braided wire, you want to be fairly quick, otherwise you'll heat the wire up under the insulation. The hot wire can melt the insulation and/or wick solder up under the insulation. That can create a breaking point if the wire moves around the point where the solder stops.

If you're having a lot of problems, practice getting the rhythm down. It's a lot about timing. If you're still having issues, maybe try a different iron or tip if it can be replaced. Also, use a 37/63 tin/lead solder. It's much easier to work with than the lead-free varieties, as it melts at a lower temperature and behaves better.

The tip of the soldering iron must be "tinned" which is a thin coating of clean shiny solder. Many soldering irons are cheap without any temperature control which causes them to be too hot and vaporize the rosin in the solder and leave the tip a mess of charcoal.

- - - Updated - - -

Also, use a 37/63 tin/lead solder.
The numbers are backwards. it is 63/37 tin/lead solder.

I suspect Stranger12 is in Europe, possibly the UK so tin/lead solder is not available any longer due to ROHS directives.

Multicored, lead free solder is still available though from many sources (Farnell, Maplin, RS, Rapid etc.)


To solder well, you have to complete a joint in under 2 seconds, else the PVC covering on wire melts. So the iron tip needs to be tinned, you should be able to feed thin solder straight on to the tip and it should melt immediately producing some smoke as the flux boils off. You do more damage with with an iron that's too cool then an iron that's too hot. Keep the bit clean by wiping quickly on a cotton rag NOT nylon/polyester as these melt or a natural sponge which is kept damp by sitting in a saucer of water. if you cannot get a shiny soldered covered tip, it will never work.
Poke your solder iron tip onto the junction of wire strands on a tag/lead on a PCB. Feed some solder from the reel on the joint. It should melt and flow over the junction, when there is enough solder on the joint, withdraw the iron and solder. DO NOT move the wire or lead until the joint has solidified, or you will get a "dry" joint.
Practise, practise, practise.

Have you tried searching Google and Youtube for how to solder?

There must be oodles of videos on the subject.

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