Thermal Gap Pads

Thermal Gap Pads
Product name	Color	Thickness (mm)	Hardness (Shore00)	Specific Gravity	Thermal Conductivity (W/m·K)	Thermal Impedance(˚C·in²/W)(1mm@10psi)¹	Dielectric Strength (kV/mm)	Dielectric Constant @1MHz	Volume Resistivity (ohm·cm)	Flammability Rating
HGP14	Grey	0.5-2	60	3.3	14.0	0.1	-	8.3	1.0 x 10¹³	V-0
TGP1200	Blue	0.5-5	30	1.7	1.2	1.03	5	4.5	4.0 x 10¹²	V-0
TGP1500	Grey	0.5-5	40	1.8	1.5	0.94	5	5.5	2.0 x 10¹³	V-0
TGP2000E	Red	0.5-5	50	2.3	2.0	0.95	-	5.5	1.0 x 10¹⁴	V-0
TGP3000	Yellow	0.5-5	40	3.1	3.0	0.65	5	6.6	4.8 x 10¹³	V-0
TGP3000E	Green	0.5-5	50	2.9	3.0	0.50	>10	5.5	1.0 x 10¹⁴	V-0
TGP5000	Blue	0.5-5	45	3.3	5.0	0.3	5	5.0	8.0 x 10¹³	V-0
TGP6000	Grey	0.5-5	40	3.3	6.0	0.25	5	8.5	3.79 x 10¹⁵	V-0
TGP7500C	Brick Red	0.5-5	20	3.5	7.5	0.16	7	8.1	1.0x10¹⁵	V-0
TGP8000	Grey	0.5-5	30	3.4	8.0	0.2	5	8.3	6.47 x 10¹⁵	V-0
TGP8000HV	Grey	0.5-5	60	3.5	8.0	0.2	8	8.3	6.47 x 10¹⁵	V-0

All values mentioned above are typical values and not product specifications. The technical data contained herein are intended as reference only. Please contact Honeywell or Caplinq for assistance and recommendations on specifications for this product.

Frequently Asked Questions

Frequently asked questions about Thermal Gap Pads

What is the standard size and tolerance of Thermal gap pads?

TGP model thermal gap pads are available in standard sheets and also custom die-cut parts, and in a range of thicknesses. It is very important to understand that the applied pressure will directly affect the bondline thickness and the thermal impedance values

Thickness Range: 0.5-5.0mm with 0.25mm incremental

Thickness Tolerance: >1mm, ±10% 0.5-1mm, ±0.1mm

What is the dielectric strength of Thermal Gap Pads?

Unless it is otherwise listed, the dielectric strength of the gap pads is around 5 - 7 kV/mm while High voltage versions have a dielectric strength around 7.6 - 7.9 kV/mm. Since air voids can occur it is hard to guarantee the exact Breakdown Voltage but you can take 5000V as the base value for non HV version pads. We are actively researching higher Dielectric Strength product versions. Contact us for developmental pads that can reach up to 9.6 kV/mm.

What happens after the expiration date?

Product shelf life is guaranteed when it is stored in the suggested conditions under controlled humidity. After the product "expires" the most readily observed response is precut pads (kiss-cut) tend to stick to each other and there is difficulty peeling out one without damaging adjacent one. There will be some viscosity change that may or may not affect thermal performance and we will not test or recertify material. We will not be liable for product quality or performance issues if expired parts are used in manufacturing.

What is the risk involved in using PCM Materials after the shelf life?

The material could potentially still be used after the shelf life. The risk involve in using materials after their shelf life is the inherent moisture absorption of all polymers, including these PCM materials as well. Moisture related failures are a big concern, and could severely impact the TIM performance. However, an expert in TIMs shared that if the material is baked (>100 °C) for a certain period of time (~30 min), the build up moisture could be evaporated quite easily and used afterwards. We will not be liable for product quality or performance issues if expired parts are used in manufacturing.

What is a Gap Filler?

Gap filler is a Thermal interface material that exists between heat dissipating and heat generating surfaces and takes up the tolerance variation.It is silicon based, filled with TC fillers such as Bn,Zn and Alumina and comes in sheet (gap pad) or dispensable (putty) form.

What holds the thicker thermal gap pads together?

Thermal Gap Pads thicker than 1mm are reinforced with a fiberglass lining.

What is the operating temperature of Thermal Gap Pads?

Thermal Gap Pads are normally used in operating temperatures up to 80°C - this being the maximum temperature of the surrounding area. However, because of chemistry of these pads, they can easily withstand temperatures from -60 up to 200°C

Can a 2mm thick Gap Pad be supplied in a Tape and Reel Format?

We cannot provide reel format for 2mm thermal gap pad. Different process was tried for the rolling packaging but wrinkles always occurs for 2mm thickness and it cannot get recovered.

Learn More

A gap filler material is a type of thermal interface material to fill the gap (>0.5mm), while phase change material and thermal grease are designed for thin bondline thickness (<0.1mm) applications. It is expected to be compliant enough to deflect to accommodate multiple module heights and tolerance variation within applications without generating excessive levels of pressure within the system. Thermal gap pads, thermal putty pads, two-part hybrid gels, and one-part hybrid gels are all considered as gap filler materials.

Key Features Of Gap Filler

Key Features of TGPs

TGPs are Silicone-based

Gap fillers are usually silicone based because silicone a lot of attractive properties such as excellent surface wetting, high thermal stability, flexibility and physiological inertness. The silicone matrix is filled with thermally conductive fillers such as boron nitride, zinc oxide or alumina. These fillers make up the functional portion of the gap filler which give it its thermal properties.

Thickness & Thermal Conductivity

Standard thicknesses of gap fillers tend to be 0.25-5mm (10-200 mils). This thickness range allows the gap filler to deform and fill these gaps without exerting excessive pressure that could damage components or reduce mechanical reliability. Most have thermal conductivity ranging from 0.5 to 10 W/mK, which effectively provides a thermally conductive path for heat transfer.

Conformaility

Gap fillers are often expected to deflect 10 to 70 % of their initial thickness (compression) without generating excessive pressure and bleeding issues.

Convenient Packaging Forms

These materials are usually delivered as die cut parts between release films, on a roll, as sheets or in cartridges for automated dispensing

Thermal Gap Pad Selection Guide

Thermal conductivities, boneline thickness and reliability capabilities are the most important considerations for TIM selection. This also works for thermal fillers like thermal gap pads. However, there are some other features need to be considered specifically for gap filler pads:

Selector Flow

Compression

Some compression (at least 10% compression) is required to overcome/decrease the contact thermal resistance. The relationship between deflection and compression is not linear. You could find the Stree-Strain Curve of compression properties on each product page. For example, the figure below shows the TGP8000 and high breakdown volatge version TGP8000HV's compressibility and how TI (thermal impedance) & Thickness change by compression ratio.

Difference between Peak Stress and Residual Stress

In gap compression applications, particularly involving thermal interface materials (TIMs), peak stress and residual stress represent different stages of mechanical behavior during and after compression. Peak stress refers to the maximum stress exerted on the material during the compression process. It occurs at the moment when the TIM is being compressed to bridge the gap between surfaces, and it reflects the material's initial resistance to deformation. A higher peak stress typically indicates a stiffer or thicker material, which may require greater force during assembly.

In contrast, residual stress is the remaining stress in the material after the compressive force has been released. It reflects the material's ability to retain pressure and maintain contact over time, which is critical for long-term thermal performance and mechanical stability. Residual stress provides insight into the elastic recovery or permanent set of the TIM, influencing how well it continues to conform to surface irregularities and maintain thermal conductivity throughout its service life.

TGP8000 Compression Data With TI and Deflection

Thickness Tolerance

When starting the design process, identify the nominal gap and know the tolerances. The thickness range of thermal gap pads we provide is 0.5-5.0mm with 0.25mm incremental. Thickness Tolerance: ±10% while thickness>1mm; ±0.1mm while thickness is 0.5-1mm

Hardness

Ideally, the softer the gap filler material, the better, since high assembly pressure may cause gap bleeding out and components deformation. However, materials that have a higher thermal conductivity and more curing extent, the harder it gets due to the high filler content. It is harder for high TC product to own elasticity and bounce back while pressure is moved away.

Additional Layer

Some reinforcement carriers might be added on normal gap pads to enhance specific properties as customers need. Some common ones are:

Woven Fiberglass (no PSA) to provide reinforcement against tearing down and a clean low tack interface surface
Polyimide Film Or PEM Film to offer an excellent dielectric strength and permit gap pad to see a shearing motion
Aluminum Foil (with PSA) to allow a pressure sensitive adhesive on the gap pad

Minimize Thermal Pad Bleeding

The biggest issue we face with silicone pads is bleeding. Surprisingly enough there are no set test methods to control bleeding of Thermal gap pads. As a general rule of thumb there's NO thermal gap pad in the industry right now that doesn't bleed. Silicone pads can and will bleed given the right circumstances, regardless of manufacturer. That doesn't mean that Silicone free pads are not prone to it. Silicone free pads will also bleed. They will just not bleed Silicone.

Bleeding is different than outgassing. It concerns longer molecular chains and it depends on a variety of parameters. Bleeding depends on the pressure differential on the pad, how much free (not cross linked) silicone remains and the molecular weight (length) of the remaining unlinked chains.

thermal gap pad bleeding

In this case, pressure plays a much bigger role than heat and orientation. Compared with competitors, we minimize bleeding largely. Check the comparison of bleeding results below:

TGP8000 bleeding comparison

Enhance Thermal Gap Pad Breakdown Voltage

While bleeding tests are not standardized, Dielectric strength testing is quite straightforward. The sample is placed between two 25 x 25mm Copper electrodes in ambient temperature and 65% ambient relative humidity while the voltage is raised by 0.1kV/s until the AC current crosses through. Optically, this cross through is usually in a form of a pinch/hole in the material, sometimes invisible to the bare eye. Tests are being conducted in a Dielectric strength tester - HJC-10KV at the time of writing of this content.

Honeywell's TGP8000HV has the lowest Thermal impedance out of all the entire thermal gap pad portfolio, plus higher breakdown voltage than the plain TGP8000 version. Check the dielectric strength data of TGP8000HV below.

dielectric strength TGP8000