Indium Blog

Specifying Flux for Pure Indium Preforms

  • Flux
  • Indium
  • Solder Preforms

  • Pure indium preforms can be supplied to you as bare metal, or with a flux coating. Do you know your flux options? Here is a list of questions that will help us to identify a flux coating recommendation for you (assuming we know what alloy the preforms will be made from):

    1. Does the flux need to conform to any specifications or classifications?

    2. What surface finishes will you be soldering to?

    3. Do you have flux residue cleaning capability?

    Let’s bring in an expert from Technical Support, Meagan Sloan, to recommend a flux for our indium preform application.

    Jim: “Hi Meagan, could you help me select a flux for a new pure indium preform application?”

    Meagan: “I'd love to help you. First, I’ll need to know what metallizations you have, and what type of flux you are looking for. We have flux coatings, tacky fluxes, and liquid fluxes.”

    Jim: “Let’s go with ENIG as our surface finish. I want to use a standard indium reflow profile and I'd like to flux-coat my preform. I don’t have any requirements for flux classification, but I’d like to make sure it is a no-clean flux.”

    Meagan: “The two flux coatings that I would suggest would be NC-7 and NC-9. I would recommend NC-7, which is an ROL0, because ENIG is such an easy surface to solder to and you are using a standard profile.”

    Jim: “Wow, that was easy. Thanks!”

    Can we help recommend a flux for your application?

    This post is part of the “Complete Intro to Pure Indium Preforms” series

    Authored by previous Indium Application Manager Jim Hisert