Soldering is a form of welding used to secure electronic components to printed circuit boards. The process of fusing unlike metals with a third liquid metal is difficult and requires practice. In addition, there are many ways you can solder something incorrectly and not know about it until much later when the solder joint fails, so it's important to really know solder those through-hole components.
Instructions
Prepare to Solder
1. Purchase a quality soldering iron. While inexpensive soldering irons work, they have no temperature control and often don't have replaceable tips. A good soldering iron will either have analog or digital temperature control, an indicator light and have replaceable tips. The type of tip you want for for soldering through-hole components is a "conical" or "pencil" tip.
2. Purchase solder and other various tools. Invest in lead-free solder with a high silver content (silver has better electrical conductivity) and a very thin gauge. Other tools you may need are solder suckers and solder wick to correct soldering mistakes, a soldering iron stand if your iron didn't come with one, a PCB vice for holding your PCB and some flux.
3. Heat up the soldering iron. Before attempting to solder, the iron must be heated completely. Start heating the iron several minutes before you start soldering. The exact amount of time will differ depending on your soldering iron.
4. Dry fit all components before beginning to solder. Put all through-hole components in their proper place in the Printed Circuit Board (PCB) and double-check the schematic to make sure they're the correct components in the correct place.
5. Clean the PCB and components. If the component leads and solder pads on the PCB are not shiny and clean, they should be cleaned before use. If there is any oxidation on the component leads, consider getting new components as this can often cause problems later. You can optionally apply some flux just before soldering which will clean the components since the soldering iron burns the flux off.
6. Tin the soldering iron tip by melting a bit of solder on the soldering iron tip. Adding a bit of solder--just enough to make it shiny-- to the tip aids heat conductivity. Wipe off the excess solder using a damp sponge.
Begin Soldering Components
7. Heat the components. This is the most difficult part of soldering, since good heat conductivity needs both solid contact and pressure. Place the tip of the soldering iron so it's touching both the solder pad and component lead and apply gentle pressure. Both the solder pad and the component lead must be heated to a temperature high enough to melt the solder. If only one of the surfaces is hot enough, the solder will not form a correct bond and you'll get a cold solder joint.
8. Apply some solder. Touch the solder to the component lead or solder pad, but do not touch it to the soldering iron tip. Keep feeding solder into the joint until the space fills with solder.
9. Take the solder away from the solder joint. Be sure to do this before removing the iron or the solder may solidify and stick the solder spool to the solder.
10. Take the iron away from the solder joint. The entire process from the moment you heated the components to this step should have taken no more than a few seconds. This takes some practice to get right.
11. Examine the solder joint. The liquid solder will solidify in a second or two. Once solidified, the solder should form a "shiny tent" of solder over the joint. It should not be bulging, bulbous or uneven. If it's not shiny, the solder was not hot enough. If you make a mistake, heat the solder with the iron and take it away with the solder sucker. Wait for the components to cool before trying again.
12. Clean the soldering iron tip. To remove excess solder, roll the tip on a damp sponge.
13. Cut the component lead off just above the solder joint with wire cutters or angle cutters. Be sure to keep a finger on the component lead as these can easily fly off and hit you in the eye.
14. Wait for the soldering iron to heat up again before doing the next joint. Every joint you solder will cool the soldering iron down. If you don't wait for the soldering iron to heat up again, you'll make cold solder joints.
Tags: soldering iron, solder joint, component lead, solder component, solder component lead, solder will