Indium Blog

Nickel Felt Applicator

I’ve always thought that the “nickel felt applicator” needs some explaining.  …And a picture.  …Heck, why not just get a video of the darn thing in action – right?  Well, that’s what we did.  The tool is used in various manual soldering operations, and appears on documents such as our Bonding Non-Metallic Materials Using Indium and High Indium Alloys” application note.  After years of explaining what a nickel felt applicator is; now we can show you how it works too.


Basically, the nickel felt applicator is like a finger sized solder “broom”.  (For lack of a better term.)  It is used to push an alloy across a surface to spread the alloy out.  In the video shown here, it is spreading pure indium onto a metallized silicon wafer, heated to 200°C.  (I had to make this somewhat semiconductor packaging related.)   You’ll also notice the solder is quite oxidized.  It is actually the scrap material from the picture I took for an old blog entry over a year ago.  It has gotten a lot of use since then, and it has developed its fair share of dross too.


My favorite part about the nickel felt applicator is that after you are done using it, the leftover alloy is easily peeled off of the applicator.  No heat is needed.  The applicator is generally supplied with a layer of indium already attached, so be sure to strip off the indium if you're planning on using a different alloy.