What Is Soldering Paste?

By Richard Asmus
Image by Flickr.com, courtesy of Windell Oskay

Whether soldering tiny electrical circuits in a computer, or copper water pipes in your plumbing, you need to use soldering paste, sometimes called flux. Without it, your electrical connections may come apart or your pipes may leak.

Purpose

Soldering paste serves three purposes. It helps clean the copper as it heats, it helps the solder flow more evenly and it helps the solder adhere to the copper.

Paste Flux

Paste flux can come in several types of containers, including a flat can, a tube or a small bottle. It contains cleaning chemicals in a resin base.

Tinning Flux

Tinning flux has a small amount of solder mixed into it, which puts a small amount into the joint before heating. Personal preference and craftsmanship determine whether this makes soldering easier.

Application

To apply flux to copper pipes, use a small brush, often provided with the flux when you buy it. For electronic circuits, dip the soldering iron tip, the solder itself and/or the wire directly into the can of flux.

Flux Core Solder

Some solder, called resin core or flux core, comes on a spool-like wire and has a center core filled with soldering paste. Most electronics technicians prefer flux core solder.

About the Author

Richard Asmus was a writer and producer of television commercials in Phoenix, Arizona, and now is retired in Peru. After founding a small telecommunications engineering corporation and visiting 37 countries, Asmus studied broadcasting at Arizona State University and earned his Master of Fine Arts at Brooklyn College in New York.