Most thermal pads, also known as thermally conductive gap filler pads, thermal gap pads, or thermal gap filler pads, have many different layer materials or carrier substrate options to choose from. It can be confusing which layer is supposed to stay on the product and which layer gets peeled off and removed before application. In fact, it’s one of our customer’s most asked about questions and can cause a lot of confusion on the manufacturing floor.
So, which layer should you peel off and which should stay on the thermal gap pad? Read on to find out.
Parker Chomerics, like many thermal gap pad vendors, offers several different gap pad layer options that must be peeled away before the gap pad is installed into the application.
Think of a thermal gap pad as a sandwich of layers -- there is always a blue poly backing that keeps the gap pad together, but there are five additional carrier substrate options which provide the following benefits:
The woven fiberglass carrier option provides reinforcement and a clean break / low tack interface surface, allowing for re-use of the thermal pad if necessary or for prototyping.
As you can see from the diagram, you peel off the liner to expose the woven glass carrier which does not get removed from the thermal gap pad.
Example: THERM-A-GAP HCS10G.
Aluminum foil with pressure sensitive adhesive (PSA)
The aluminum foil with PSA carrier’s primary function is to allow a pressure sensitive adhesive on the thermal gap pad to affix the thermal pad in place.
As you can see from the diagram, you peel off the liner to expose the aluminum foil carrier which does not get removed from the thermal gap pad.
Example: THERM-A-GAP A579.
Polyethylenenapthalate (PEN) film
The polyethylenenapthalate (PEN) film carrier permits the thermal gap pad to see a shearing motion and offers a clear, cost-effective dielectric film with fair thermal performance.
As you can see from the image at right, there is no clear film to peel off that exposes the PEN film carrier, which does not get removed from the gap pad.
Example: THERM-A-GAP 579PN.
Thermally enhanced polyimide
The thermally enhanced polyimide carrier permits the thermal gap pad to see a shearing motion and offers an excellent dielectric film with enhanced thermal performance.
As you can see from the image at right, there is no clear film to peel off, the polyimide carrier does not get removed from the gap pad.
Example: THERM-A-GAP 579KT.
The no carrier or “un-reinforced” option allows the thermal gap pad to have high tack surfaces on both sides, allowing for the pad to be highly conformable, but it does make cutting and handling of the product more difficult.
Once the liner is peeled back, there is no additional carrier on the thermal gap pad, the pad is now exposed.
Example: THERM-A-GAP 579.
Blue poly diamond carrier
Lastly, the base carrier liner, shown in blue, is persistent on the bottom of all thermal gap pad options, and must be peeled and removed prior to installation of the thermal gap pad.
This blue carrier is necessary, as it keeps the gap pad intact and more easily to handle prior to installation. We recommend keeping this blue poly carrier layer on just until the gap pad is placed for the final time.
This blog was contributed by Jarrod Cohen, marketing communications manager, Parker Chomerics Division.