TGP1500 aka Gap Pad 1500 stacked
NEDC manufactures many different types of thermal pads. Customers ask us all sorts of technical questions about thermal pads. One question we get all the time is:
“My Gap .250’’, can I stack this Thermal Gap Filler Pad that only comes in .125’’ , twice?”
Potential Problems with Stacking Thermal Pads
Let’s start by responding to that question- Can you stack, or layer thermal interface pads? Well, it is not recommended:
There are several reasons for this:
- Delamination will be a lot more prevalent- as there is a space in there.
- The thermal performance will go down. This is because presumably there are tiny thermally impeding air-gaps still in the thermal pad lamination.
- We did not do reliability testing in any of these tests, and we are not confident how it would perform during application performance.
- It can create problems while die-cutting, or otherwise converting. However, I should mention that I was surprised how well the pads stayed together, and adhered together during lamination, and die-cutting. At one point I mixed up the two pads during testing because they looked so similar after lamination.
Thermal Pads Stacked/Layered Tested
In this experiment, we did a total of eight tests. We stacked 4 different pad types, at different thicknesses to see what the different thermal outcomes may be. Since we are a Henkel/Bergquist distributor, I figured we’d test their thermal pads. We tested TGP 3000, TGP 5000, TGP 1500, and TGP 1000VOUS. We stacked at a number of thicknesses, and a number of pressures to get a good sampling of how this would play out in a real application. All of the W/m-K values are expressed in apparent thermal conductivity which includes contact resistance. Below is a table that outlines what we did.
| Products | TGP5000 aka GAP PAD 5000S35 (10, 25, 50 psi) | TGP1500 aka GAP PAD 1500 (10, 25, 50 psi) | TGP3000 aka GAP PAD 3000S30 (10, 25, 50 psi) | TGP 1000VOUS aka GAP PAD VOUS (10, 25, 50 psi) |
| Test 1 | Tested at .125’’ (5.42 W/m-K, 5.49 W/m-K, 5.49 W/m-K | Tested at .160’’ (1.26 W/m-K, 1.36 W/m-K, 1.37 W/m-K) | Tested at .125’’ (3.39 W/m-K, 3.59 W/m-K, 3.60 W/m-K | Tested at .125” (.923 W/m-K, 0.975 W/m-K, 0.984 W/m-K) |
| Test 2 | Tested at .125’’ (.060’’ Stacked) 4.83 W/m-K, 4.90 W/m-K, 4.93 W/m-K | Tested at .160’’ (.080’’ Stacked) 1.26 W/m-K, 1.36 W/m-K, 1.38 W/m-K) | Tested at .125’’ (.060’’ Stacked) 3.25 W/m-K, 3.57 W/m-K, 3.48 W/m-K | Tested at .125’’ (.060’’ Stacked) .901 W/m-K, .908 W/m-K, 0.941 W/m-K |
As you can see, stacking thermal pads adds additional thermal impeding air that makes the thermal pad overall less effective, but not to a significantly statistically relevant point.
More Information on Stacked Thermal Gap Filler Pads
NEDC manufactures many different types of thermal gap fillers pads through die-cutting, waterjet-cutting, and knife-cutting. For more information on thermal interface pads, or you believe you could utilize a pad that has been stacked, please contact sales@nedc.com.