Soldering Technique


This page is a brief introduction to proper soldering technique.   Solder is pronounced "sodder", the "l" is silent. This page assumes you will be soldering the components to a PC (printed circuit) board.  The directions below will get you acquainted with some construction techniques.

Soldering irons, wire, PC board holders and other supplies are in 310.   The soldering irons are on timers so that they can't accidentally be left on, but you should try to remember to turn them off when you are done.  

Installing a component.

To install a component on the PC board, first hold the board with the component side facing you.  This is the side of the board with writing on it.   Start with the smallest components, usually the resistors.  Bend the leads of the device (if necessary) so that they will fit through the hold in the board with the device laying flat against the board.  Now bend the leads on the solder side of the board so the device doesn't fall out (see below).  You can place several components at the same time.

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After several components have been "stuffed" (the technical term for putting components on a board), you can solder them.  Before soldering anything make sure the sponge on the soldering stand is moist.  You should frequently wipe the tip of the iron on the sponge to keep it clean. 

To solder a component turn the board over so the solder side is up.   There are some clamps for holding boards in the lab.  To solder a connection hold the tip of the soldering iron on one side of the lead and hold it for a second or two.  When the lead and the trace are hot, apply solder to the side of the lead that is away from the iron.  The solder shouldn't touch the iron directly.  This ensures that the connection is hot enough to form a bond with the lead and with the copper trace.

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The solder should flow around the connection, and leave a smooth transition from the trace to the lead, as shown.  If you have a ball, or the solder has a clumpy appearance you may need to redo the connection.  If you need to remove solder we have "solder-suckers" and "solder-wick".

Good Solder Joint Bad Solder Joint
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Repeat this procedure with all components until you are finished.

Other references about soldering that you may find useful:

Soldering faq from "Everyday Practical Electronics"  Includes some good photographs (1, 2) and techniques for desoldering.

Soldering primer from New Mexico State University

Another soldering primer

Comments or Questions?