Category Archives: Thermal Interface Material

The primary objective of most electronics cooling applications is to keep the junction temperature of a hot component within an acceptable level in order to increase the longevity and performance of the device.  In most cases, this requires some sort of heat spreader or heat sink to assist in the heat transfer.  This also almost always needs to include some kind of thermal interface material to reduce the resistance between the IC and the heat sink.  You have all kinds of choices really in this respect:

• Grease (very good, and very messy)
• Phase Change Material (as good as grease but requires consistant pressure over time)
• Thermal Tape ( does a good job, cheap, tough to rework a chip when you have to remove the heat sink)
• Epoxy (please, do not go there!  Does the job, ruins your IC’s)

There are alot of choices and frankly no one choice is best as they all have specific spaces where they can be used effectively.  ATS’s Thermal Lab has written a nifty white paper on this.  We published it in our QPedia Thermal Journal but are linking to it here.   So, if you need to know more about this topic, please click to:  “When to Use a Thermal Interface Material With your Heat Sinks and Why?“

Nusil Technology has a new low outgassing, thermal interface silicone material available.  It’s EPM-2495P offers some interesting specifications including Thermal Conductivity* 0.64 W/(mK).   It looks like it may take some work to use, requiring some mixing and curing and it requires a vacuum chamber to remove any air introduced during mixing.  But, for low outgassing needs, Nusil’s EPM-2495P might be a good answer.

Of course, that begs the question, why?  Why would you need to go to the trouble of a low outgassing thermal interface material?  Because in some cases, outgassing 0f a material can interact with either the involved heat of the device being cooled or the chemicals in the material to which it’s outgassing too.   The result can be a breakdown in these material, reduced reliability and potentially reduced functionality.

And speaking of Thermal Interface Material, ATS’s thermal team wrote an informational article on Phase Change Interface Material that our readers might be interested in.  Phase change material offers many of the benefits of grease with far less of the complications.  Click to Phase Change Materials for Transient Electronics Cooling to have a read.

Of course, in extreme situations only grease will do.  And were outgassing is a critical need, Nusil’s It’s EPM-2495P might be the best approach too.

As many of our customer’s know,  ATS is a big believer in phase change thermal interface material. Certainly every type of thermal interface material has it’s correct place in a design, from thermal tape to grease, but we feel that phase change material can do a terrific job technically and economically. In fact, we invented maxiGRIP to allow for phase change material to be better used. Bergquist now has released a new family of phase change material named, “Hi-Flow 330P“.

Hi-Flow 330P features a thermal impedance of only 0.18°C-in2/W (@25 psi).  It also features one dry side and one naturally tacky side to accommodate efficient handling and dispensing. Bergquist’s new material is electrically insulating, with its polyimide reinforcing film providing dielectric strength higher than 5 kV and high resistance to cut-through. Learn more by visiting the 330P web page, “Hi-Flow 330P”

Just a note on applying steady, consistant PSI. The best way to do that is via a metal spring clip, and maxiGRIP frame clip which deliver a steady, consistent force to apply the heat sink to a given chip. Click on this presentation at Digi-Key to learn more facts as to why.