Home >> Science & Nature >> Science

The Leak Resistance of Soldering Tips

An electronic circuit is typically created on a printed circuit board by soldering individual electronic components, such as capacitors, into the material. However, soldering tips can produce leak resistance, or excessive electrical voltage and current movement, that damages sensitive electronic components. A well-maintained soldering iron is key for a functional, everyday tool.

Soldering Iron Features
- A soldering iron resembles a large pen or pencil. A cylindrical handle attaches to an extension called a heating element. The heating element is encased in a metal element cover. The end of the soldering iron's heating element assembly is a soldering tip. When the soldering iron is plugged into power, the heating element warms the tip until solder, or metal alloy, can visibly melt from a simple touch. The solder is melted onto PCBs for attaching electronic components to the circuitry's body.
Leak Resistance Considerations
- As a soldering iron is used, solder and flux reside on the tip. Over time, this melted metal build up, creating an oxide layer. This oxide layer begins to create leak resistance. Leak resistance is the soldering iron's opposition to passing electrical current and voltage to the components being actively soldered. As leak resistance increases with excessive oxide layers on the soldering tip, more electrical current and voltage is passed through the tip to the PCB. Excessive leak resistance leads to component damage from electrostatic discharge, also known as static electricity.
Industry Standard
- The United States Military Standard (MIL standard) requires that all soldering tips must generate less than 5 ohms of leak resistance at the soldering iron's highest heat setting. However, many manufacturers try to improve on this requirement, producing soldering irons and tips with a maximum leak resistance of 2 ohms.
Care
- Reducing the possibility of an ESD component failure from leak resistance requires periodic cleaning. Clean the soldering tip and attached element cover with sandpaper or steel wool. These abrasive materials will remove any oxide layers from the soldering iron's length. In addition, soldering iron users can test the leak resistance value by using an ohmmeter. Place one ohmmeter lead on a cooled soldering iron tip and the other lead to the unplugged ground prong on the power cord. The resistance reading on the ohmmeter should bet 2 ohms or less.

Science