Indium Blog

A Look Inside the Solder Flux Pen

Here is a picture of an Indium Corporation solder flux pen, sectioned to show you the internals.  Who DOESN'T want to see THAT, right?!?

Flux pens are commonly used to accurately supply small amounts of flux to parts before soldering. In the case of hand soldering solar cells, this is the perfect packaging. As you press the flux pen tip (the yellow part in the picture) against your solar cell, the spring-loaded tip assembly moves back into the body of the flux pen, opening the valve and releasing a small amount of flux into the upper chamber. The pen tip, made of a felt material, carries the flux to the outer surface via capillary action. As you move the flux pen tip across the cell metallization, a thin, even trail of flux is deposited on the surface.

Although flux pens are designed for all types of hand soldering/rework applications, the felt tips generally measure 1.5mm x 4.25mm. This size is great for various sizes of tabbing ribbon!

If you’d like to try using flux pens filled with the best tabbing fluxes available, contact us at

Authored by previous Indium Application Manager Jim Hisert