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I know the proper way of soldering wires and other components on PCBs and breadboards is by first heating up the joint with the soldering iron and then feeding it solder.

However, the breadboards that my Electronics teacher is giving us at school are so small that I can't have the soldering iron and the solder both on the same joint, which makes it more difficult to make a good joint. Instead, would it work if I heated the joint I wanted to solder, and then place solder on that joint and then put the tip of the soldering iron on the solder.

Theoretically, that should make a good joint, although I just wanted some feedback before actually trying this next week at school, in case I make a big mess.

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    \$\begingroup\$ If you look at the component lead coming up through the PCB hole, typically the solder iron tip comes from one direction, and the solder comes in from the opposite direction. In other words, there is a separating plane between the solder iron tip and the solder, and the component lead is in this plane, and the PCB is normal to this plane. If this is the case, how could the tip and the solder not both fit? It doesn't matter how small the lead is or how fine the pitch is, as they come in to make a joint from different directions. \$\endgroup\$ – Jon Watte Oct 6 '13 at 17:53
  • \$\begingroup\$ Stupid question: Have you looked into acquiring a soldering iron with a smaller tip? What about smaller-gauge solder? \$\endgroup\$ – John R. Strohm Oct 7 '13 at 0:28
  • \$\begingroup\$ @John R.Strohm I did say I was doing this at school and we're not exactly made of money to be buying modern solders when we feel like it \$\endgroup\$ – 83457 Oct 9 '13 at 16:22
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Yes, that is called tinning. But tinning won't make the best connection without adding some solder on top as well.

By breadboard, I assume you mean some type of protoboard, probably smaller than 0.1" spacing? Then your soldering iron tip might be too big, but even 0.05" spacing boards are easy to do with most standard tips. You might just need practice. Heck, people hand solder 1mm pitch with no problem. Also, use flux. It draws the solder towards it. You can also add the solder to the iron.

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Yes, this should work, but requires a bit of experience.

There are few things to watch for:

  • Cold joints - you did not apply enough heat after adding the solder, therefore part of the solder didn't melt
  • Insufficient Wetting - the solder did melt, but you did not heat the pad (or the pin) enough which resulted in insufficiently good contact.

The above are not issues when you apply heat to pads/pins and feed solder afterwards because only after the pad/pin are hot enough and the solder melts, will the solder flow onto the pad/pin.

Make sure that you heat up both the solder and the pad/pin underneath. However, try not to burn components or detach pads. The latter requires a bit of experience :)

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i find that to first a establish good mechanical tension between the components helps because then i hold the iron tip firmly against the thickest material, usually a copper wire. the heat transfers through the wire, heating the pad, and then i stick the solder in the angle gap from the side and it just goes, whoop, sucks in there, and i can get the iron out quickly to avoid lifting the pad with excessive heat.

it doesn't usually work well to heat the solder because it melts and spreads out before transferring the heat to the underlying component

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