How to Avoid Common Mistakes When Using Paste Solder

Correcting mistakes when working with paste solder can be particularly difficult. Using solder paste can be a fun little thing to do, however you want to make sure to do it right. Following are a few important tips and tricks to help you if you are new to paste soldering process to get the best results.

Avoid Overheating or Underheating the Solder

I think one of the most common mistakes that people make using solder paste is not heating it enough or overheating the solder itself. Excessive heat turns solder into a mass with no functionality. That means it won’t adhere the pieces together the way it should. Conversely, too little heat will not melt the solder properly and it will make no solid connection. To avoid this error — and some readers may be wondering how this happens — you will need to heat up the solder evenly and gently. Use your torch on a low to medium heat setting. A good tip is to also make circular movements with the torch while heating. This helps distribute the heat evenly through the solder so that it melts correctly.

Use the Right Amount of Flux

There is also flux which is part of the solder paste as well and allows the solder to flow evenly and adhere to the contacts you are soldering. One of the most common mistakes people make is to apply too little flux or apply it unevenly. When the solder flows up towards the heat source, however, this can leads to weak solder joints that can easily crack. To prevent this blunder from happening, use a thin, even coat of flux on the area onto which you'll be soldering and don't rush. Like any good chemistry experiment, this is done by successfully applying in an even layer, preferably with a small brush or applicator. Ensure that the flux spreads over the whole surface, for the solder to flow and adhere properly.

Use Solder — But Not Too Much

Using too much or too little paste solder is another common paste mistake. Using too much lead free solder paste can make for a messy joint, too much is not only unsightly, but can also lead to cracking. Too little solder would result in a weak bond that may not hold the pieces together securely. To fix this, try to use as much solder as needed to evenly spread across the joint. The less, the better, and only if you need it, add more. Just keep in mind that you're using the individual lead pads as your guides, so be careful and precise when applying the extra solder, because once the extra solder is down, it's kind of hard to remove.