Two Part Hybrid Thermal Gel

Dispensable and Reworkable


Two Part Hybrid

Two part hybrid thermal gel products are two-component, dispensable, thermally conductive gels, which offer long-term reliability and superior softness. The enhanced bonding force between the polymer base and the filler minimizes oil separation issues in storage.

Those two component, dispensable, thermal hybrid gels require very low compression force and can be used for vertical mounting. Prior to curing, the materials maintain good thixotropic characteristics and low viscosity to be easily dispensed. Additionally they show minimal post cure oil bleeding / separation and no pump out and cracking. Their excellent adhesion and high reliability makes them the top choice for Automotive applications. At the same time the ability to cover varying heights and their end properties make them an ideal thermal interface for MM wave wafer antennas and specifically 5G applications.

Two component hybrid thermal gels can be cured in a short time after two-component mixing at room temperature. HLT series thermal gels require curing but very little pressure during installation (5-10psi or the weight of a heatsink is sufficient). You can speed up the process by curing at elevated temperatures (80 -100°C).  The high compressibility minimizes thermal resistance at interfaces, making hybrids ideal for low stress applications while maintaining excellent performance during reliability testing. They are generally considered slower due to the mixing stage but they make up for it with their end properties. They exhibit low contact resistance, long term reliability while they are also easy to dispense and rework. 

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Compare Products
8 products

Product Selector Guide

Thermal Two-Part Hybrid
Product name Color Viscosity (cps) Hardness (Shore00) Specific Gravity Thermal Conductivity (W/m·K)

Thermal Impedance (˚C·in2/W) 

Breakdown Voltage (kV/mm)

Cure Schedule 

25˚C (hour)

Cure Schedule

100˚C (min)

HLT 2000 Yellow + White 200,000–350,000 50 2.8 2.0 0.66 > 10 10 30
HLT 2000LV White +
Dark Red
200,000–400,000 35 2.8 2.0 0.60 - 16 30
HLT 3000 White + Blue 100,000-200,000  50 3.1 3.0 0.45 > 10 18 -
HLT 3500 White + Blue 300,000–450,000 40 3.2 3.5 0.44 > 10 12 30
HLT 7000* * * * * 7.0 * 8.5 * *
HLT 10000* * * * * 10.0 * - * *

*Since those are top of the line products, we go to certain extends to protect Honeywell\'s IP and competitive advantages. A plethora of information,  including additional data,  images and samples are available once an NDA is in place. Contact us for more details. (They\'re really really good)

**Typical values for electrical properties on our high end products are: Dielectric constant@1MHz: 9 and Volume resistivity: 1013Ω*cm

**Lower conductivity materials have much lower filler content and therefore have even higher volume resistivity which makes them more insulative. 

Frequently Asked Questions

Are Two component thermal hybrids considered phase change materials?

No they are not. Why are they called hybrids and not thermal gels then? Hybrids (Both one and two component) share ingredients and compounds between Thermal Gels and Phase Change materials. They combine the best of both worlds and use additives that can be found in Phase Change formulations.

This combination allows the HLT series to reach the highest thermal conductivity in the market (10 w/mK) while at the same time reaching bond lines suitable for 5G Applications. In fact , HLTs are being successfully used by the largest 5G manufacturers in the world. 

What are some common applications for Two component hybrid thermal gels?

Typical Two part hybrid gap filler Applications include:

  • Consumer electronics
  • Telecommunications equipment
  • Automotive electronics
  • Memory and power modules

Are Two-Part Hybrid Gel product cured or not cured?

It is not very accurate to use the word “Cure”. One part hybrid gel is fully cross-linked, while two-part gel is not fully cross-linked. It needs 2 hours for a two-part hybrid to cure. Process is: you first dispense the gel onto the surface, then apply pressure and it will spread and thin down, leave the gel to cure in place

What are the differences between one-part and two-part hybrid gels?

Not really much in texture and thermal properties. Two part system requires multiple adapter heads for two part to mix and curing 2 hrs@RT. We always say that one-part is better to use for horizontal application but two-part hybrid is suitable for both. This is because two-part cure in place, it has better adhesion to heatsink surface.

However, you always need to get trade off between adhesion and rework-ability. So even for two-part hybrid, it is not strong adhesion, just slightly higher than one-part. For small size device (consumer electronics), you could also use one-part for both directions.

What are the texture of thermal hybrid gel? Are they adhesives?

They won’t be like rubbery elastomer, still gel form, not perform elastically. When you apply pressure, the gel will spread and think down. If you remove pressure afterward, it will not bounce back and turn to the original form. Among all the TIMs, only gap pad with low TC could recover back. That is also why, for gap pad, even you tear off it from the heatsink, you could still reconnect and use the same material. But for other materials, you need to remove them and apply new material again.

Thermal hybrid gel is not designed as a structural adhesive and has a low level of natural tack, which will allow the material to adhere mildly to adjacent components. This also help keeping the material in the interface throughout repeated temperature cycling and eliminates pump-out from the interface.

What are the applicable temperature range and pressure for hybrid gel?

Thermal hybrid gel products are silicone based products. All the silicone-based thermal products could be used up to 200 °C.

Hybrid gels need less 10psi to reach BLT 0.1mm – 1.0mm; but PCM needs higher pressure and suitable for 0.03-0.05 mm application

Learn More

 Key Performance Benefits For Choosing Thermal Hybrid Gel

Hybrid is a substance between liquid and solid. Hybrid thermal gel, prepared as a silicone polymer, with low molecular siloxane, and mixed with high thermal conductivity particles (such as alumina, aluminum nitride powder, etc.). As thermal conductive liquid gap fillers, hybrid gels offer good dispensing and thixotropy properties for automated assembly processes. They not only have the benefits of conforming to complex shapes and strong material cohesion, and also good long-term thermal stability. Caplinq provides pre-cured hybrid and two-part hybrid products that require mixing and curing steps. 

The key benefits of choosing thermal hybrid gel products are summarized:

Reliability Compared to thermal grease, the main difference is that thermal hybrid does not present oil separation issues while in storage. Compared to gap pads, there is no pump-out or cracking risk. The Hybrid can be torn off and reused.
Compressibility High compressibility minimizes thermal resistance at interfaces, while maintaining excellent performance during reliability testing. Thanks to the ultra-low modulus, the gap filler creates minimal stress on components during the assembly process, which makes it applicable for most of the fragile and delicate devices.
Flexibility Hybrid gels offer infinite thickness and shape options, and are able to conform to intricate topographies, including multi-level surfaces. They are a single solution for multiple applications. Rheological characteristics could also be adjusted to suit different requirements.
Productivity Prior to curing, the material maintains good thixotropic characteristics and low viscosity to be easily dispensed. The material could be applied directly to the target surface by manual or automatic dispensing, which improve productivity and precisely control the application process with minimal wastage.
Properties comparison in details between different types of thermal interface materials could be found at Learn More - Comparison TIM.
  Two-Part Hybrid Gel V.S. One-Part Hybrid Gel

The HT series is one-part hybrid gel, which is already fully cross-linked before being applied. It could save time in assembly process and has longer shelf life. The HLT series products are two-component gels that can be cured in short-time after two-component mixing at room temperature. For details process handling guide, please refer to HLT Products Application Note and HT Products Application Note products are cured in place, thus have better adhesion to components and are suitable for both horizontal and vertical applications. In total, the two series products share similar thermal and electrical properties.

Compared Properties One-Part Thermal Hybrid Gel Two-Part Thermal Gel
Dispensing Rate Medium Quick
Curing Needed No Need Yes, 2 hours @Room Temperature
Assembly Stability Horizontal Assembly Preferred Horizonal & Vertical Assembly Both Applicable
Thermal Conductivity A Wide Range Up To 11 W/mK A Wide Range Up To 11 W/mK
Assembly Pressure Required Low, < 10psi Low, < 10psi
Work Life Long Medium
Shelf Life 12 months @RT, <65%RH 6 months @RT, <65%RH
Reworkability Good Medium



 Thermal Hybrid Gel Thermal Property Measurement

Thermal impedance testing

Two part hybrid thermal gels exhibit exquisite thermal characteristics with Thermal conductivity reaching 10 w/mK. But how do those thermal properties change with pressure and bond line thickness?

To identify this we used a TI tester to test thermal impedance under ASTM D5470 requirements. The temperature was kept steady at ~75°C and the sample (a 1" diameter circle) was tested in a pressure ramp starting from 5 and resulting to 50psi. At this point we need to reiterate that we focus on TI, as a more valuable "real life" value and that our properties are never overstated.  So what you see in the Technical data sheets is what you get.

thermal impedance tester
thermal filler tests

Effects of pressure on BLT & TI

As expected, when applying pressure, the bond line thickness drops significantly while at the same time thermal impedance drops too. Those properties tend to stabilize halfway but there\'s room for improvement for both BLT and TI, which maximize (technically minimize) their values at 50 psi.

It is worth pointing out that  HLT10000 is starting with very low Bond line thickness and minimal Thermal impedance that both slightly improve with pressure. It is remarkable that the presureless BLT starts at extremely low BLT while at the same time having an unrivaled TI. This makes HLT10000 the most High end thermal interface material in the market with out of the box properties that are second to none.


 Thermal Properties Test Method

Thermal impedance test method: Cut bar

All of our product properties are tested based on strict and regulated test method standards such as the ASTM. The test method always accompanies the product properties. We try to undershoot rather than overshoot the product capabilities so that you always get at least the advertised properties (and usually much better than that). We pride ourselves in providing "spot on" stated properties.

fourrier's law of conduction
measuring thermal conductivity

Thermal conductivity is an easy way to categorize products and it is true that this is the leading property in our product nomenclature. At the end of the day though, Thermal impedance is what makes the real difference. That\'s why most of our technical discussions revolve around these values. In order to test it we have implemented various methodologies such as the Cut bar method that is demonstrated in this image.

This methodology is based on ASTM D5470 (at the time this content was written) and is a destructive, one time test with fast and immediate results. One of the most common methodologies that we use for Thermal impedance.

Thermal impedance test method: Laser Flash

Another test, suitable for accelerated life testing, is the Laser flash method. With ASTM 1461 (current) we measure the thermal impedance between Si, Ni plated Cu surfaces.This method includes the CTE mismatch and the actual surface finish.

Laser flash takes thermal diffusivity into account and the calculation follows the logic in the image. Typical coupons used are:

  • Ni plated Copper -0.5”X0.5”X0.03”
  • Si - 0.5”X0.5”X0.02”

Please note that these methodologies are not strictly limited to one part hybrid thermal gels but they also extend to out entire thermal interface product line, when applicable.

how to measure thermal conductivity
measure thermal conductivity of thermal gels