Why Is IBM Underfill Blue?

Why Is IBM Underfill Blue?
IBM, known as Big Blue, manufactures an underfill materials that is blue. Is there a technical advantage to blue underfill?
Mysteries of Science


IBM has been been known as Big Blue for decades even using blue as their corporate color. One of their electronic materials, underfill, is also blue.

Underfill is a liquid used on some computer chips to enhance their connection reliability.

Most underfills are black, the traditional color of electronic packaging material. The black comes from carbon ink, a form of soot that is often added to plastics to make them opaque and give them strength.

You would assume that Big Blue was manufacturing blue underfill as a marketing gimmick. However no one at IBM thought this was the case, and they thought the idea was a bit tacky.

Was there a technical engineering advantage for IBM to manufacture blue underfill?

Here's the rest of the story.

When IBM developed their underfill, they knew colorants would need to go through safety and health hazard testing, and this could take months, maybe even a year. Someone got an idea for a shortcut.

Why not look for an existing and approved IBM product that used an approved colorant. It didn't take long to come up with "green solder mask" as the easy choice.

The chemists were soon talking to the solder mask formulators, but discovered that IBM did not buy green colorant. They mixed yellow and blue colorants to produce green solder mask.

The simplest solution was to choice was to go with the blue pigment and not worry about mixing to produce green. Since the blue pigment was safety-approved, it was just a matter of adding some to the underfill. And that's why IBM underfill is blue.


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