FAQ

Method of choose thermal pad: first select the thermal conductivity and
then select the hardness.

Method of choose thermal tape: first select the thermal conductivity and then select no substrate and then select raw materials.

Method of choose epoxy potting compound: select the thermal conductivity .

Thermal grease (also known as heat paste, heat-conducting silicone, heat-conducting heat paste, wafer cooling paste) is a viscous fluid substance that is filled with incomplete flat and smooth surfaces between the components, which have a greater heat Conductivity, can effectively enhance the cooling effect of components.

LED thermal management: 
LED is developed for lighting energy because of its high performance and significant energy saving potential.
Since the total amount of light generated by a single LED is much lower than that of other lighting sources, it is necessary to increase the forward current and the number of LED groups to increase the total output of light.
However, both of these solutions will increase the junction temperature and reduce the performance of LED.
As the operating temperature increases, the intensity of light decreases, the lifetime decreases, and the light color changes.
 

LED thermal management:
- Ambient air temperature
- Thermal path between LED and radiator
- LED performance

T-Global's thermal series products meet the key factors in the thermal path between the LED and the radiator
Using the correct heat sink can significantly reduce the junction temperature that has a profound effect on LED life

Thermal interfacial materials (TIMs) are thermally conductive materials, which are applied to increase thermal contact conductance across jointed solid surfaces, such as between microprocessors and heatsinks, in order to increase thermal transfer efficiency. These gaps are normally filled with air which is a very poor conductor.

They take many forms. The most common is the white-colored paste or thermal grease, typically silicone oil filled with aluminum oxide, zinc oxide, or boron nitride. Some brands of thermal interfaces use micronized or pulverized silver.

Another type of TIMs are the phase-change materials. These are solid at room temperature but liquefy and behave like grease at operating temperatures. They are easy to handle and are not messy.

Thermal compound (also called thermal gel, thermal grease, thermal paste, heat paste, heat sink paste or heat sink compound) is a viscous fluid substance, originally with properties akin to grease, which increases the thermal conductivity of a thermal interface by filling microscopic air-gaps present due to the imperfectly flat and smooth surfaces of the components; the compound has far greater thermal conductivity than air. In electronics, it is often used to aid a component's thermal dissipation via a heat sink.

Illustration of the heat flow between a heat sink and circuit board using T-Global S606 Thermal Grease

Thermal conductivities

For comparison, the approximate thermal conductivities of various materials relevant to heatsinks in W/mK are:

1. Air 0.034

2. Water 0.58

3. Thermal grease about 0.5 to 10

4. Unbranded grease typically 0.8; some silver-and graphite-based greases claim about 9

5. Aluminium oxide (surface layer on aluminium) 35

6. Steel About 40, varies for different types

7. Aluminium 220

8. Copper 390

9. Silver 420

These figures vary slightly between sources, and depend upon purity, etc. of the material. Other units are sometimes used, obviously giving different numerical values.

These are bulk thermal conductivities; the thermal resistance of a particular interface (e.g., a CPU, a thin layer of compound, and a heat sink) is given by the thermal resistance, the temperature rise caused by dissipating 1 W, in K/W or, equivalently, °C/W. For example, a thermal pad of specified area and thickness will be rated by its thermal resistance. A typical value for a pad for a microprocessor is roughly 0.2 °C/W per square inch, dependent upon thickness and decreasing at high pressure.

Purpose of Thermal Compound

Thermal grease is primarily used in the electronics and computer industries to assist a heat sink to draw heat away from a semiconductor component such as an integrated circuit or transistor. Thermally conductive paste improves the efficiency of a heat sink by filling air gaps that occur when the imperfectly flat and smooth surface of a heat generating component is pressed against the similar surface of a heat-sink, air being approximately 8000 times less efficient at conducting heat than, for example, aluminum (a common heat sink material). Surface imperfections and departure from perfect flatness inherently arise from limitations in manufacturing technology and range in size from visible and tactile flaws such as machining marks or casting irregularities to sub-microscopic ones not visible to the naked eye. Thermal conductivity and "conformability" (i.e., the ability of the material to conform to irregular surfaces) are the important characteristics of thermal grease.

The importance of thermal conductivity:

The thermal conductivity and heat dissipation capacity of the heat dissipation device are closely related to the life and performance of the product of the electronic product. Thermal Conductivity

High thermal conductivity material or thermal conductivity interface material directly to the thermal conductivity of the higher capacity. Thermal conductivity has a variety of different titles, common thermal conductivity, heat transfer, heat transfer, thermal conductivity, thermal conductivity, thermal conductivity, thermal conductivity, heat transfer coefficient and thermal conductivity.

Key parameters of thermal interface material - Thermal conductivity:

Heat transfer coefficient (heat transfer Coefficient), also known as heat transfer coefficient (k) in W / mK, thermal conductivity formula k = (Q / t) * L / (A * T), where k is the thermal conductivity, Q is the heat, t is the time, L is the length, A is the area, T is the temperature difference; is used to measure the energy per unit time conduction.

Design of the thermal conductivity of the interface material is the key parameter of the thermal conductivity, select the best performance (high K value) products are not necessarily necessary, hardness, thickness, heat area is also an important design considerations. When the other parameters are equal, the higher the thermal conductivity represents the more efficient thermal management.

The k-value interval of the thermally conductive interface material:

Low k value: 1 - 3 W / m-k

In k value: 4 -6 W / m-k

High k value: 6 - 12 W / m-k

Thermal conductivity of different substances at room temperature Reference table:​

Thermal grease and thermal pad are auxiliary CPU cooling, as far as possible to achieve the maximum cooling efficiency CPU fan. What is the difference between the two?

Thermal pad  is generally used in some inconvenient to apply the thermal paste place, such as the host version of the power supply part of the current version of the power supply part of the heat are relatively large, but the mos tube part is not flat, So you can paste the thermal pad. In addition, the graphics card under the heat sink, the need for multiple parts of the card with the different parts of the contact, thermal paste is also more inconvenient to use, can be replaced by thermal pad.

In addition to some of the above reasons, the following lists the difference between the CPU thermal paste and thermal pad:

Thermal effect: When thermal conductivity of the same, the thermal conductivity of the thermal grease is better than the thermal pad. Because the thermal insulation is smaller, if you want to achieve the same thermal effect, thermal conductivity of the thermal pad must be higher than the thermal paste.

thermal grease	thermal pad

Thermal tape, with good thermal conductivity, strong adhesive and low thermal resistance in one which has these features can replace thermal grease and mechanical fastening while applying. To go a step further, the temperature of electronics devices will go down after thermal tape fill the uneven interface between the heat source and metal products (ex: heat sink).

Usually, there are two main type of thermal tape, one is Acrylic based pressure sensitive adhesive (PSA), the other is Silicone based pressure sensitive adhesive (PSA). Acrylic one is suitable be placed with metal and ceramic products, and silicone one is suitable be placed with plastic products. At the same time, they also can be capable with fiberglass mesh or Polymide as extra reinforcement carrier to increase the ratio of stiffness and break down voltage.

Thermal tape is an ideal thermal material for attaching small, or long and thin dimension of electrical components, due to the adhesive and thermal conductivity, especially the tiny chip on PCB, LED lighting, or panel application.

In previously electronic devices, there are barely requirement about thermal solution for chip. However, with the improvement of technology, the electronics devices contains more and better fancy function currently, but smaller volume. Then RD engineer start using small heat sink to solve the overheat issue, that’s also the common application of thermal tape. Obviously, thermal requirement is increasing day by day for sure. Meanwhile, T-global technology will keep providing the latest and best thermal solution for customer!

The instruction of thermal tape:

1.Measure the dimension you need, and cut into the specific size. Or provide the dimension to your consultant then we will cut into specific shape accordingly.

2.Remove the PET film carefully, and attach smoothly and gently on the interface you choose.(Heat source or heat sink)

3.Using fixed frame before the glue of tape affects and sticks two materials if the volume of heat sink is heavy or big.

Except thermal conductivity and adhesion, the hardness, working temperature, break down voltage and reinforcement carrier are also the important factors for choosing thermal tape.

The thermal product of thermal tape from T-GLOBAL

What's the application of thermal tape?

Feature: Superior adhesion and thermal conductivity, easy to assemble.

Application: LED lighting, Panel, ic etc.

The advantage of thermal tape:

1.Easy to assemble and bond the chip and heat sink than thermal grease, and decline the defection rate for covering uneven thermal grease on design.

2.Another assembling way for choice, except the screw and push pin to fix the components.

When the thermally conductive materials are heated, will the materials separate out? 

Most of thermal pad products have silicone oil composition, T-Global is treated by a special process of high temperature chemical treatment, and through special treatment twice high temperature chemical treatment, and use the hot vacuum treatment to solve the gas silica oil precipitation problem. We develop non-silicone thermal pad to solve the problem of oil leakage.

How long can we use the thermal pad?

The thermal pad products from T-Global, It comes with the substrate silicone rubber. It can use 20 years normally. But Thermal pad's life depends on how you use it.

When the thermal materials be heated, will it change its hardness?

The thermal pad products from T-Global, it comes silicone rubber's nature property. In the -40 - 200 ℃ working environment will not be significant changes can be easily used for assembly.

What is the mean of your company's thermal material comes with micro-viscosity?

The thermal pad products from T-Global, it comes with silicone rubbers nature property with micro-viscosity. It can assemble more conveniently when you use it. With micro-viscosity, it is spall easily and also can avoid strip.

Does the surface of the thermal pad have a micro-stick?

The thermal pad from T-Global comes with micro-stick. It can make customer position conveniently and heavy industry operations, to avoid tearing itself. So the operator can easy to remove from the chassis and heat sink re-use. Please rest assured to use the use thermal materials products from T-Global.

 
What kind of thermal pad do we have?

*Well rework effective in preventing resonance, avoid noise, isolate, to support, avoid EMI (The series of FAM)

*high softness、compressibility and thermal property. (The series of TG)

*high insulation strength, great thermal conductivity (The series of L37, The series of H48)

*electrical insulation, smooth interface,Applicable within the range of constant temperature radiation (The series of TG)

Do Thermal materials can offer adhesive?

L37/H48 from T-Global can do adhesive, and pass SGS, every piece of thermal pad can do adhesive.

What is the composition of the heat-conducting silicone film?

ent, crosslinking agent, flamThermal pad is based on silicone,

It adds thermal powder, pigme retardant and Catalyst. After a special process of processing and synthesis, it become a material with heat, insulation, flame retardant. It mainly used to fill the electronic components of the heat source surface and the heat sink or heat between the shell, the heat transfer interface.

What are the characteristics of thermal pad?

Thermal pad has a very soft, flexible, strong compressive, the surface comes with natural micro-stick, paste well, good insulator,

Very good thermal conductivity, Thickness selectivity diversity,fill up the tolerance of electronic components，Chemical stability, use for very long time, can reuse……

How to use thermal pad?

Thermal pad can operate very well, you just need to gently tear off the protective film, and then put it between heat source surface and heat sink or heat sink.

What is the application of flame retardant thermal pad?

It can use in electronic industry, like LED light, Switching power supply, household appliances, LED TV, mobile devices, network equipment, communications equipment, IC chips, circuit board and heat sink between the filling, machine boxes, CPU and other electronic appliances industry.

What else can we use thermal pad?

According to customers needs, thermal pads can adhesive, one side adhesive, two side adhesive. We produce thermal tape, thermal conductive graphite sheet, potting compound, to meet different customer needs.
Thermal conductivity of silicone film basic specifications: 300 * 300MM, thickness 0.2 ~ 20.0MM.Customize with suitable thermal tape can also be provided in coil form.

The expiry date of cement

You need to use it no longer than three months or it will be reduced viscosity.

Will the silicone material be hard for a long time?

A little bit, probably(Shore A or Shore00 2~3)。

As the heart of the computer, CPU heat is quite amazing.          

General CPU through the thermal paste to heat into the radiator, so as to achieve the purpose of cooling. When CPU heat is too high, system will occur blue screen, crash, restart and so on. So the CPU heat conduction becomes particularly important. So, when installing the cooling fan, it is best to apply the thermal grease between the heat sink and the CPU. The role of thermal grease is not just making the CPU produced by the heat quickly and evenly passed to the heat sink. Many times, the thermal grease can also increase the heat sink is not flat on the lower surface and the thermal contact with the CPU. And the thermal grease has a certain viscosity. In the case of fixed heat sink metal shrapnel slightly aging loose, the heat sink will not be separated from the CPU surface. It maintains the effectiveness of cooling fan.

Illustration of the heat flow between a heat sink and circuit board using T-Global S808 Thermal Grease

What is the effect of the thickness of the thermal grease on the heat dissipation?

In theory, in ensuring that the CPU / GPU and heat sink surface gap can be filled under the premise of the thermal layer is the thinner the better. After all, from the thermal performance speaking, the thicker the thermal material will increase its thermal resistance.

How to apply the thermal grease to have a better effect?

This question should not have a standard. But there are some tips: The key is to smear, to be uniform, no bubbles, no impurities, as thin as possible. There are two way to apply it now. One is squeezing the thermal grease in the CPU / GPU and the other is  surface center, and then rely on the pressure of the radiator, the thermal paste squeeze evenly. Another way is to even apply the thermal grease to the CPU / GPU and other surfaces. The first method is suitable for smaller surface area heat source. The second method is more suitable for large surface area of ​​the CPU / GPU. But the second method of smear is easy to get impurities, so it may produce bubbles.

The most correct sop is:

1.First, you need to use High purity solvent（For example: High purity acetone）and lint-free cloth（like lens cloth）to clean CPU surface and the bottom of heat sink. Be careful don't touch the core and heat sink surface.（If you don't have acetone, you can use Ethanol.）

2.To ensure the area where the heat sink is in contact with the CPU, In the bottom of the radiator squeeze a certain amount of thermal paste.

How long does the CPU thermal paste need to be changed?

Thermal grease (silicone) is a liquid, but not moisture and other volatile substances. Basically, metal powder and silicone oil and other fillers are mixed. Among them, the liquid component is mainly used for the first time when the smear, so that metal particles easier to fill into the metal inside the gap with. After the first smear, basically 2 to 3 years as long as there is no loosening phenomenon no need to fill again.

The category of thermal interface material includes thermal pad, thermal tape, thermal grease, thermal putty etc. TIM can fill the gap(0.1mm~20mm) between heat source and heat sink as a bridge to accelerate the efficiency of heat dissipating , cool down IC's temperature, increase its life and improve the performance.。

Illustration of the heat flow between a heat sink and circuit board using T-Global Li-98 Thermal Conductive Adhesive Tape

Thermal module consists of thermal interface material, copper block, heat pipe, heat sink and fan etc. Heat transferring from heat source, through TIM , copper block and heat pipe to heat sink. The TIM with larger thermal conductivity and area has better thermal performance. If the temperature of IC is high , the space in the device is small or the air flow in the device is bad, we will suggest to add a fan in your design to help dissipating the heat.

TIM can be used in a wide range of electronic products like notebook, laptop computer, telecom device, LCD TV, LED lighting equipment, power supply Unit PSU, DDR Memory Module etc.

Below are the different types and composition of thermal interface materials:

1. Thermal potting compound: the heat curing gel composed of epoxy/or silicone and oxidized metal powders.

2. Thermal tape: double side adhesive with acrylic base, silicone base material are available. Some items with fiberglass mesh or polyimide can meet the special functionality required by customer

3. Thermal pad: One is solid pad, the other is phase change material which will turn to liquid when the temperature exceeds 50℃.

The key element when selecting thermal interface material:

1. The material: Silicone or non-silicone(like acrylic base, epoxy base)

2. Thermal conductivity: Most of the TIMs K-value is between 0.98W/mK~12W/mK. Some special items can reach 400 W/mK,1500~1800 W/mK are also available.

3. Hardness: Shore00 25~ShoreA 90 are available

Compression rate:

Please notice the instruction in our SPEC to optimize the thermal performance.

Working environment:

Please notice the instruction in our SPEC to ensure the working safety.

Choosing the proper thickness of thermal interface materials is very important, especially silicone as the based material. The ideal compressibility is between 15~20%, and depend on the different hardness with various item.

The compressibility of thermal interface material:

The main propose of thermal interface material is to fill the uneven interface and air hole between two materials (Heat source and heat sink) then dissipating heat out efficiency. With better connection and filling is the key point to apply thermal interface material. 

Hardness is a key factor when choosing TIM(Thermal Interface Material). Generally, the harder TIM has stronger support to the component. The softer TIM has lower thermal contact resistance. As comparing with same type TIM(same thermal conductivity), the softer one will show better thermal performance.

Standard test method:

Shore (Durometer) hardness is one of several common used measures of the hardness of a material. Higher numbers indicate harder materials; lower numbers indicate softer materials. For example, the hardness of TG2030 (Shore00 30) is softer than L37-3(Shore00 55).

In computing and electronics, thermal pads (also called thermally conductive pad or thermal interface pad) are a pre-formed square or rectangle of solid material (often paraffin or silicone based) commonly found on the underside of heat sinks to aid the conduction of heat away from the component being cooled (such as a CPU or another chip) and into the heat sink (usually made from aluminum or copper). Thermal pads and thermal compound are used to fill air gaps caused by imperfectly flat or smooth surfaces which should be in thermal contact; they would not be needed between perfectly flat and smooth surfaces. Thermal pads are relatively firm at room temperature, but become soft and well able to fill gaps at higher temperature.

For special applications, non-silicone thermal pad may be required. Most commonly seen is Acryl-based non-silicone thermal conductive pad. The applications may include electronic components: IC、CPU、MOS、LED、M/B、P/S、Heat Sink、LCD-TV、Notebook PC、PC、Telecom Device、Wireless Hub、DDR II Module、DVD Applications、Hand-set applications, etc.