How to Choose a Solder

by Andy on March 31, 2008

According to Dictionary.com, solder is defined as “any of various fusible alloys, usually tin and lead, used to join metallic parts.”

Solder is used by electronics manufacturers, electricians, jewelry makers, plumbers and even hobbyists.

The first step in choosing a solder is to decide what metals are going to be bonded, because the type of metal used will greatly influence the type of solder used. Soft solders are often used with copper, tin and brass. These solders have a low melting point and are made of tin (Sn) and lead (Pb). Soft solders also come in different proportions of tin and lead. Common ratios are 60/40, 50/50 and 63/37. The first number is always the amount of tin in the solder.

Kester Lead Free SolderLead-free solder is another variety of solder that is becoming more popular. Electronics products that contain lead (as well as other hazardous materials) are banned from the European Union as part of the Restriction of Hazardous Substances (RoHS). Lead-free solder may contain many metals including silver, copper, tin, bismuth, indium, zinc and antimony.

Hard solders have a high melting point and are usually made with a high proportion of the metal being soldered. Also, lead is not used in hard soldering. Hard soldering is often used for jewelry making. Because of the high melting point, a hand held torch is usually used in place of a soldering iron.

Solder comes in various forms. The most common forms of solder include, wire, bar and paste. Solder in wire form is probably the most popular because it comes conveniently packaged as a roll. The wire comes in different thicknesses and can be used directly on the circuit board with a soldering iron.

Solder bars are for wave soldering and solder pots. Wave soldering is large scale soldering of components to printed circuit boards (PCBs), while solder pots are used for tin wires/leads.

On the other hand, soldering paste is often used with a syringe. The paste is applied and then heated using hot plates or hot air guns. A disadvantage of soldering paste is that it needs to be kept cold and it will spoil after a few months.

Once you start researching solder, you’ll realize that the price of solder is flexible. The price fluctuates based on the current market price for the metals used in the solder.

Solder chemicals often go hand in hand with solder. Flux is a common soldering chemical. Flux chemically cleans the metals that are going to be soldered together. It is important to remove flux afterwards because the chemical can corrode the metal which could lead to future product failures.

FYI, here are some of the reasons why soldering is such a popular bonding method.

  • Correctly soldered joints can last for years, plus the joints are reliable.
  • For the most part, soldering is easy to do and inexpensive
  • An experienced solderer has control over the entire process
  • Options for solders, irons and tips are endless

Looking for more information on Kester solder?

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