Customers are looking for the best thermal performance when it comes to thermal interface materials. To get the best thermal performance, in my opinion in most cases, you don’t want to rely on much external pressure to get there. For that reason, we thought we’d write a post on some low pressure thermal pads that typically will compress without much pressure, and provide some great thermal performance in the process. These low pressure thermal pads are good for a number of applications.

AI thermal pad chip

Why is High Deflection, Low Pressure Important?

Laird/DuPont offers a variety of low pressure thermal pads that are categorized as “high-deflection”.  These pads are known as TFlex HD90000, TFlex HD80000, TFlex HD7.5, TFlex 700, Tflex HD300TG, and TFlex HD300. What does this mean? It means that the pad has a low amount of pressure required to get the pad to be at a good performance level. We have discussed before the importance of a pad to deflect to be able to provide good thermal performance. Here is the challenge with thermal pads:  Filling the pad with hard fillers such as ceramic, or diamond, or whatever magic dust makes the pad brittle. When the pad becomes brittle, it becomes very hard to extract good thermal performance because you are required to put a significant amount of pressure on the pad to extract said performance. This can cause two problems:

  1. The pad, and accompanying pressure will smash delicate components on the board such as SMD (surface mount devices) components. This can be a critical failure point in application. Imagine putting a ton of pressure on a CPU- you’d be concerned about cracking, or otherwise damanging the components.
  2. The pad can suffer itself because so much pressure is put on it from batch to batch, it can crack under the pressure. It may not perform as intended because the pad breaking can cause air gaps. In addition, it can flow out too much if it depends on external pressure to achieve proper wet-out.

With these low pressure thermal pads, most of the compression you would ever want out of the pad is achieved within 20 psi. For example, we included the TFlex HD90000 compression/deflection chart here, and most of the deflection is easily achieved within 20 psi.

Why is High Deflection, Low Pressure Important?

Laird/DuPont offers a variety of low pressure thermal pads that are categorized as “high-deflection”.  These pads are known as TFlex HD90000, TFlex HD80000, TFlex HD7.5, TFlex 700, Tflex HD300TG, and TFlex HD300. What does this mean? It means that the pad has a low amount of pressure required to get the pad to be at a good performance level. We have discussed before the importance of a pad to deflect to be able to provide good thermal performance. Here is the challenge with thermal pads:  Filling the pad with hard fillers such as ceramic, or diamond, or whatever magic dust makes the pad brittle. When the pad becomes brittle, it becomes very hard to extract good thermal performance because you are required to put a significant amount of pressure on the pad to extract said performance.

low pressure thermal pads

This can cause two problems:

  1. The pad, and accompanying pressure will smash delicate components on the board such as SMD (surface mount devices) components. This can be a critical failure point in application. Imagine putting a ton of pressure on a CPU- you’d be concerned about cracking, or otherwise damanging the components.
  2. The pad can suffer itself because so much pressure is put on it from batch to batch, it can crack under the pressure. It may not perform as intended because the pad breaking can cause air gaps. In addition, it can flow out too much if it depends on external pressure to achieve proper wet-out.

With these low pressure thermal pads, most of the compression you would ever want out of the pad is achieved within 20 psi. For example, we included the TFlex HD90000 compression/deflection chart here, and most of the deflection is easily achieved within 20 psi.

TFlex HD Product Performance/Availability

TFlex HD90000 – 7.5 W/m-K- .040”-0.200” available thicknesses, HD91000, HD91250, HD91500, HD91750, HD92000, HD92250, HD92500, HD92750, HD93000, HD93250, HD93500, HD93750, HD94000, HD94250, HD94500, HD94750, HD95000

TFlex HD7.5 – 7.5 W/m-K- .040”- .200” available thicknesses 

TFlex HD80000- 6 W/m-K – .040”-0.200” available thicknesses, HD81000, HD81250, HD81500, HD81750, HD82000, HD82250, HD82500, HD82750, HD83000, HD83250, HD83500, HD83750, HD84000, HD84250, HD84500, HD84750, HD50000

TFlex HD700- 5 W/m-K- .020”- .200” available thicknesses, HD720, HD740, HD780, HD7100, HD7140, HD7200

TFlex HD300TG- 2.7 W/m-K -0.020”-.200” available thicknesses

TFlex HD300- 2.7 W/m-K -0.020”-.200” available thicknesses, HD340, HD360, HD380, HD3100

Note: CoolZorb™  HD500 is a high-deflection pad too with nearly double the compression of CoolZorb™ 500 under the same pressure. This pad deflects 50% deflection at 40 psi. 

Distinctions of TFlex Thermal Gap Fillers From Before:

Lairds’ DuPont came out with a few TFlex thermal pads that came out before. When doing new designs of thermal interface materials, NEDC suggested the following:

TFlex 700 should now use TFlex HD700

TFlex 300 should now use TFlex HD300

TFlex 300TG should now use TFlex HD300TG

While all the above thermal pads are still available as of September 2024, we suggested new designs incorporate the above thermal pads for a great cost/benefit ratio.

Applications for High Deflection Thermal Interface Pads

-Artificial Intelligence/CPUs

-Power Supplies

-Data Centers with High Power Density

More Information on TFlex/Thermal Pads

NEDC provides thermal pad die cutting services for customers. For more information on high deflection thermal pads or if you have an application that you believe could benefit from a high deflection thermal pad, please contact sales@nedc.com.

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