How do I solder?
- Make sure the surfaces to be soldered are clean.
Turn on the soldering iron and set temperature above the melting point of your solder. 600°-650°F (316°-343°C) is a good place to start for lead-based solder and 650°-700°F (343°-371°C) for lead-free solder.
Hold the tip against both the lead and contact point/pad for a few seconds. The idea is to bring both up to a soldering temperature at the same time.
Touch the solder wire to the lead and contact point/pad a few times until solder flows around the lead and contact.
Inspect the solder joint to make sure there is full coverage over the contact area and lead. If it is a thru-hole lead, the hole should be filled and the solder joints a slight pyramid shape.
If necessary, trim the lead with a shear lead cutter. Do not trim into the solder joint, which can damage the connection.
If using rosin activated flux, aqueous flux, or if the aesthetics of the flux residue is a problem, clean the area with a flux remover.
How hot do I set the solder iron?
600°-650°F (316°-343°C) is a good place to start for lead-based solder and 650°-700°F (343°-371°C) for lead-free solder. You want the tip hot enough to melt the solder efficiency, but excess heat can damage components as the heat travels along the leads, and it will reduce the life of the soldering tip.
How do I tell a good solder joint from a bad one?
Inspect the solder joint to make sure there is full coverage over the contact area and lead. Some things to watch out for:
- If it is a thru-hole lead, the hole should be filled and the solder joints a slight pyramid shape.
- If a surface mounts solder joint, the solder should fully cover the contact pad and surround the lead.
- The lead should not be loose or wiggle once it is soldered.
- The solder shouldn’t overflow or bridge onto other contact points/pads.
- If using lead-based solder, the solder joint should be shiny. Unfortunately, lead-free tends to have a duller finish, so not a good indicator in that case.
Is it ok to set the heat at maximum temperature to speed up soldering?
In soldering, like everything else, speed is king. Operators will turn up the soldering temperature to speed up heat throughput. This allows them to go from one solder joint to the next faster. The catch – the higher the heat, the shorter the tip life. Sure, solder stations may go up to 900°F, but 750°F is the highest you need to go for a lead-free wire. The extra heat can also unnecessarily stress components, increasing the chances of PCB failure later.
Why is the solder dripping off the soldering tip?
That is an indication that the soldering tip needs to be cleaned, so it is a “cold” tip (although it is still very hot, so don’t touch!). When flux and oxidation build up over time, the heat does not transfer as effectively and the solder doesn’t wet, or flow over the tip properly. The solder will tend to melt but just drip off the tip. This makes it difficult to move to solder around contact areas the way you may need it. Learn how to clean the soldering tipe here.