Thermal conductive interface material is a kind of polymer composite material with polymer as matrix and thermal conductive powder as filler. With good thermal and mechanical properties, it is widely used between the heat source and the radiator in electronic components to help form a good thermal channel and reduce the thermal resistance of the heat dissipation module. It is currently recognized as the best thermal solution in the industry.
The following types of heat conductive materials are commonly used in the market: heat conductive gasket, heat conductive insulating sheet, heat conductive adhesive, heat conductive potting adhesive, heat conductive gel, heat conductive mud and heat conductive silicone grease. Here are their advantages and disadvantages for your reference!
1. Thermal conductive silicone grease
Heat conductive silicone grease, also known as heat dissipating silicone grease and heat conductive paste, is the most widely used heat conductive medium at present. The material is a paste liquid. It is an ester formed after heating, decompression, grinding and other processes with silicone oil as raw material and thickener as filler. The material has a certain viscosity and has no obvious sense of particles. Can effectively fill various gaps; Main application environment: between high-power heating components and radiators.
(1) It exists in liquid form and has good wettability;
(2) Good thermal conductivity, high temperature resistance, aging resistance and water resistance;
(3) Insoluble in water and not easy to be oxidized;
(4) It has certain lubricity and electrical insulation;
(5) Low cost.
(1) It cannot be applied on a large area and cannot be reused;
(2) The stability of the product is poor for a long time. After continuous thermal cycling, the liquid will migrate, leaving only the filling material and losing the surface wettability, which may eventually lead to failure.
(3) Due to the different thermal expansion rates of the materials on both sides of the interface, an "inflation" effect is caused, resulting in an increase in thermal resistance and a decrease in heat transfer efficiency;
(4) It is always liquid, which is difficult to control during processing, which is easy to cause pollution, waste of other parts and materials, and increase costs.
2. Heat conductive gasket
Thermal conductive gaskets are used to fill the air gap between the heating device and the heat sink or metal base. Their flexible and elastic characteristics enable them to cover very uneven surfaces. The heat is conducted from the separate device or the whole PCB to the metal shell or diffusion plate, which can improve the efficiency and service life of the heating electronic components.
In the use of gaskets, pressure and temperature are mutually restricted. With the increase of temperature, after the equipment operates for a period of time, the gasket material will soften, creep, stress relaxation, mechanical strength will also decrease, and the sealing pressure will decrease.
(1) Preformed thermal conductive material, with convenience of installation, testing and reuse;
(2) Soft and elastic, good compressibility, able to cover very uneven surfaces;
(3) It has the effect of cushioning, shock absorption and sound absorption under low pressure;
(4) Good thermal conductivity and high-grade withstand voltage insulation;
(5) Stable performance, no oil leakage at high temperature, high cleanliness.
(1) The thickness and shape are preset and will be limited by the thickness and shape when used;
(2) The thermal conductive silicon film with a high thickness and a thickness below 0.5mm has a complicated process and relatively high thermal resistance;
(3) Compared with thermal conductive silicone grease, the thermal conductivity of thermal conductive gasket is slightly lower;
(4) Compared with thermal conductive silicone grease, the price of thermal conductive gasket is slightly higher.
3. Thermally conductive silica gel
Thermal conductive silica gel is a kind of silica gel which is made by mixing organic silica gel as the main body and adding polymer materials such as filler and thermal conductive material. It has good thermal conductivity and electrical insulation performance and is widely used in electronic components.
(1) Thermal interface material, which will solidify, has adhesive properties and high adhesive strength;
(2) After curing, it is elastic, impact resistant and vibration resistant;
(3) The cured product has good heat conduction and heat dissipation functions;
(4) Excellent high and low temperature resistance and electrical performance.
(1) Non reusable;
(2) The gap of joint filling is general.
4. Heat conductive potting adhesive:
Heat conductive potting adhesives are commonly divided into silicone rubber systems and epoxy systems. Silicone systems are soft and elastic, and epoxy systems are hard and rigid; It can meet the requirements of heat conduction potting in greater depth. Improve the resistance to external vibration and improve the insulation and waterproof performance between internal components and circuits.
(1) It has a good waterproof sealing effect;
(2) Excellent electrical performance and insulation performance;
(3) It can be disassembled for repair after curing.
(1) The heat conduction effect is general;
(4) The process is relatively complex;
(5) Poor adhesion;
(6) The cleanliness is average.
5. Thermal conductive tape:
Thermal conductive tape, also known as thermal conductive double-sided adhesive, is composed of acrylic polymer and organic silicone adhesive; It is usually used between low-power heat sources and small radiators to fix led radiators.
(1) It has both thermal conductivity and adhesive properties;
(2) It has good joint filling performance;
(3) The appearance is similar to double-sided adhesive tape, and the operation is simple;
(4) It is generally used for the surface of some electronic parts and chips with less heating.
(1) The thermal conductivity is relatively low, and the thermal conductivity is general;
(2) Unable to bond and fix the heavy objects;
(3) Once the thickness of the tape exceeds, effective heat transfer with the heat sink cannot be achieved;
(4) Once used, it is not easy to disassemble, and there is a risk of damaging the chip and surrounding devices. It is not easy to disassemble completely.
It can be seen from the above introduction that no matter which type of thermal conductive material can meet the needs of all electronic equipment, it has some shortcomings more or less. Therefore, when choosing thermal conductive materials, we should not only have a deep understanding of the performance of the products, but also choose them according to the design structure of the customers‘ own products.