1. Introduction 

Manual soldering with a soldering iron is used in the following  occasions:

1. small production runs

     In most cases the solder is applied in the form of flux-cored wire. In making soldered joints by a manual method, the operator can watch the progress of the joint formation, and adaptation of the soldering process to varying conditions, such as of solderability. With this in mind, hand soldering is still used for the making electrical connections with the highest reliability requirements, e.g. for space applications. When mass soldering is involved, quality hand soldering is not economically viable.

To assure reliable manually soldered joint requires considerable  management involvement. It must

* Assure selection and training of operators

2. Use of the soldering iron 

       Hand soldering is a skill, obtained by training and experience. Soldering irons are heated by an electrical element. The heat must be transported from the element to the tip with which the soldering is done. The metallic piece with a tinned tip, acting as heat store and heat conductor, is called a soldering bit. The temperature of the tip must be higher than the soldering temperature, because the heat transfer from the tip to the joints is relatively poor. The soldering iron should not be used as a lever. A well tinned soldering tip is indispensable for making good joints. Cleaning should never involve a file or a steel brush, but only a cloth or a wet sponge. Bits for soldering irons are commercially available in a variety of shapes, including special hollow bits for suction desoldering iron. Standardization of the tips has been proposed but has not yet been realized.

Three aspects of manual soldering are important.

I) how to operate the soldering iron

In working with surface mount components, in addition to ordinary soldering irons as detailed above, hot gas soldering and resistance soldering are used widely. Though hot gas soldering is non-contact type, resistance soldering is of contact type wherein the heating elements come in contact with the point of soldering.