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Avoid the Void®: Voiding in High-Temperature Soldering

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  • Phil Zarrow: Andy, Gold-Tin, specifically Gold-Tin 20, has been a real workhorse for a lot of high-temp applications of late. And what we're seeing is we're kind of running out of steam in some of the directions we're going.
    Andy C. Mackie, PhD, MSc: Yeah. Gold-Tin eutectic solder will be a staple diet, or a staple material, that's used in a lot of different applications from RF to LED and other higher temperature applications for the foreseeable future. What we're seeing though, is trends with Gallium Nitrites, Silicon Carbide, semiconductor devices coming along. Higher junction temperatures and the need for step soldering, where the Gold-Tin eutectic would be used as a second attached solder, after the initial die-attach.
    We're seeing a need for, obviously, higher temperature solders and it's made that a need. So, we're seeing, particularly a lot of Gold-Germanium being needed, specifically Gold-Germanium preforms.
    Phil Zarrow: Now, let's clarify what we mean by high-temp. These are not your typical circuit board applications.
    Andy C. Mackie, PhD, MSc: Absolutely not. Now organic materials, if you reach, generally, over three hundred degrees Celcius will decompose. So, we are talking primarily ceramic, sort of a butterfly packages, particularly for high-end RF applications.
    Phil Zarrow: Accordingly, we're not also talking standard equipment, we're talking specialized ovens utilizing forming gas.
    Andy C. Mackie, PhD, MSc: Correct, forming gas and the specialty ounce version. Very low oxygen, correct.
    Phil Zarrow: This is not your father-son ring application. 
    Andy C. Mackie, PhD, MSc: Well, no.
    Phil Zarrow: What are actually some of the applications? We've mentioned LED, Telecom. What specifically? What are we seeing in those applications?
    Andy C. Mackie, PhD, MSc: The vast majority of this is being used in RF infrastructure. It's being used in 4G. It looks like the move to 5G applications, which incidentally, is something that's going to be implemented in cars, probably before almost anything else. So, the cell phone repeated towers, are using these very high temperature, very high TJ devices, and it's there where the Gold-Germanium, particularly, will be used as a die-attach.
    Phil Zarrow: And, of course, as in applications everywhere in electronics, we want to try and Avoid the Void®.
    Andy C. Mackie, PhD, MSc: Avoid the Void® is critical.
    Phil Zarrow: So, Andy, we can download your paper, "The Die-attach Voiding Reduction and Gold Alloy Solder Preforms" and allow us sort of brief all this from the website,
    Andy C. Mackie, PhD, MSc: Correct.
    Phil Zarrow: And your email in case people want to send some questions to you?
    Andy C. Mackie, PhD, MSc: My email is, all one word.
    Phil Zarrow: Andy, thank you very much.
    Andy C. Mackie, PhD, MSc: Phil, as always, a pleasure.