TABLE OF CONTENTS Historically, the most common tools for hand soldering were the torch and the soldering bit (flame-heated iron). In this chapter, we concentrate on the electrical soldering iron and some modern tools required by our fast-changing industry.
Before soldering irons were heated by electricity, they were heated by flames, coals, stoves, and other direct methods. Only in 1893 was the first patent granted on an electrically heated soldering iron. At that time, most soldering irons were of the heavy variety used for sheet-metal work.
With the advent of the electrical industry, the smaller electrically heated soldering iron came into its own. Today, irons in a large variety of sizes and shapes are available to industry, the latest development being a generation of sophisticated temperature-controlled tools.
Approximately 760,000 soldering irons are sold yearly to the electronics industry (excluding sales for sheet-metal work, hobbies, home use, etc.), and it is estimated that there are more than 2 million irons in use in the electronics industry alone. In spite of the inroads that wave soldering and other automatic methods of manufacturing have made, there will always be a large number of soldering-iron applications that cannot be replaced. All touch-up, repair, and replacement on printed circuit boards is done with soldering irons, and so is all point-to-point wiring, installation in mainframes or chassis, etc. The role of the soldering iron is thus relegated from the more robust initial assembly of low-cost components to the realm of delicate operations on...
