Is your product currently struggling with the heat dissipation problem of the heating elements? Are you also worried that high temperatures will lead to a decline in product performance and a shortened lifespan? GALLOP INNOTEK is an expert in the field of heat dissipation. This article will introduce to you the heat conduction mechanism of silicone and its common forms and applications, helping you solve the problem of product heat generation and achieve your efficient production.
Is Silicone Thermally Conductive?
Whether silicone conducts heat is a question we are often asked. The answer is that pure silicone itself is a poor conductor of heat, but by adding specific heat-conducting fillers, we can make it into a heat-conducting material with excellent performance.
The Composition of Silicone
Silicone Substrate: The silicone substrate mainly serves to bond, wrap and insulate. It has poor thermal conductivity by itself, but it has excellent flexibility, stability at high and low temperatures, weather resistance and electrical insulation.
Thermal Conductive Filler: Thermal conductive filler is the key to achieving heat conduction. By adding a large amount of ceramic powders such as metal oxides or nitrides to the silicone substrate, these filler particles are interconnected, which forms countless efficient heat conduction paths within the insulating silica gel.
The Filler of Thermal Conductive Silicone
Alumina
Alumina is not the most outstanding in performance, but it has the best overall balance. It has excellent insulation, good chemical stability, low price and a mature supply system, which makes it an ideal choice for manufacturing medium and high-end thermal silicone products.
Boron Nitride
Boron nitride is also known as “white graphene”. It has a layered structure similar to that of graphite, with extremely high thermal conductivity in the opposite direction of the layers, and is also an excellent insulator. It is the material among all fillers that achieves the best balance between high thermal conductivity and high insulation.
Aluminum Nitride
The theoretical thermal conductivity of aluminum nitride is extremely high, being the top among all ceramic fillers. However, its biggest problem is that it is extremely prone to react with water vapor in the air and undergo hydrolysis, generating aluminium hydroxide with very poor thermal conductivity, which leads to a sharp decline in product performance over time. It is mainly applied to those applications that spare no expense in pursuing the ultimate heat dissipation performance and can take good sealing and moisture-proof measures.
Zinc Oxide
Zinc oxide is rarely used alone as a filler. Because of its small particle size, it is usually mixed with other large-particle fillers to fill the gaps between large particles, achieving a tighter packing, thereby enhancing thermal conductivity and reducing thermal resistance. In addition, it also has the functions of antibacterial and ultraviolet shielding.
How to Measure the Thermal Conductivity of Silicone
Thermal Conductivity
Thermal conductivity is the most important indicator for measuring the thermal conductivity of silicone, representing the material’s ability to directly conduct heat. It defines the amount of heat passing through a unit area per unit time under a unit temperature gradient. Generally, the higher the value of thermal conductivity, the faster the heat conduction speed of the material.
Thermal Resistance
Thermal resistance is a more crucial indicator for thermal silicone gel in practical applications. It represents the total resistance that heat encounters when passing through the entire interface, including the material itself and its interface with the contact surface. Materials with high thermal conductivity, if they have poor contact with the surface and air gaps exist, their overall heat dissipation effect and thermal resistance may also be very poor. Generally speaking, the lower the thermal resistance, the better the heat dissipation effect. It is affected by multiple factors such as material thickness, contact pressure, and surface flatness.
Electrical Insulation Strength
The advantage of thermal conductive silicone lies in its ability to both conduct heat and insulate. The electrical insulation strength measures its insulation capacity, which is crucial for ensuring the safety of electronic products.
To measure the thermal conductivity of silicone, the first thing to look at is the laboratory data of its thermal conductivity coefficient and thermal resistance. But more importantly, it is necessary to conduct application verification in your actual products, comprehensively evaluate their thermal conductivity, processability and reliability, which can make the most accurate choice.
Common Forms and Application Scenarios of Thermal Conductive Silicone
Thermal Grease
Form: Thermal grease is a white or gray paste that always remains in a paste state and does not solidify.
Working principle: Thermal grease utilizes its excellent fluidity to fill the microscopic uneven gaps between the heat-generating surface and the heat-dissipating surface, expelling the air with extremely poor thermal conductivity and significantly reducing the contact thermal resistance.
Advantages: The lowest thermal resistance, good fluidity and high cost performance.
Disadvantages: It has no bonding strength and dries easily, and the construction requires process control.
Applications: Between the CPU, GPU and the heat sink, the chip and the housing, high-power IGBT module.
Thermal Pad
Form: Thermal pads are pre-made sheet materials of different thicknesses and hardnesses, and can be punched into specific shapes.
Working principle: It undergoes elastic deformation under pressure to adhere to two surfaces and establish a heat conduction channel. Its thickness is used to accommodate larger assembly clearances.
Advantages: It is easy to install and the thickness is selectable. It can be reworked and has insulation and buffering functions.
Disadvantages: The thermal resistance is higher than that of silicone grease of the same coefficient, and there is compressive stress.
Applications: Between the PCB board and the metal casing, the memory stick dissipates heat, and the battery pack dissipates heat.
Thermal Adhesive
Form: Thermal conductive adhesives are usually two-component (A/B agents) or one-component liquids. After curing, it is like hard rubber and can bond permanently.
Working principle: It combines the thermal conductivity of silicone and the bonding strength of silicone resin, capable of both conducting heat and mechanically fixing components.
Advantages: Structural bonding, fixed heat sink, resistant to mechanical vibration, high reliability.
Disadvantages: Permanent bonding, non-repairable, and requires curing time after construction.
Applications: Heat sink bonding, small component fixation, sensor packaging.
Thermal Potting Compound
Form: Thermal potting compound is mostly a two-component liquid. After being mixed, it is poured into electronic components and solidifies to form an integrated solid protective layer.
Working principle: It wraps the entire heat-generating element, and the heat is conducted to the external casing through potting compound for heat dissipation, while providing comprehensive protection.
Advantages: It offers all-round protection including waterproofing, moisture-proofing, insulation and shock resistance, with uniform heat dissipation.
Disadvantages: It is completely non-repairable, has high stress management requirements and a long curing cycle.
Applications: Power module, automotive electronics, LED driver, battery management system for new energy vehicles.
The Importance of Thermal Conductive Silicone
In modern high-density and high-power electronic devices, heat dissipation is the key factor determining product performance, stability and lifespan. Thermal conductive silicone is an indispensable material in many industries.
Fill the Air Gaps
Any two seemingly smooth solid surfaces are uneven at the microscopic level. The air in these gaps is a poor conductor of heat, creating a huge thermal resistance. The core function of thermal conductive silicone is to perfectly fill these voids and form an efficient heat transfer mode.
Ensure the Stability of Functions
Modern high-performance chips consume a lot of power and generate a lot of heat. If the heat cannot be dissipated in time, the chip will automatically reduce its frequency, resulting in a sharp decline in performance. High-performance thermal conductive silicone is the key to ensuring the continuous operation of chips. It can keep devices working at a relatively low temperature and improve the energy efficiency ratio.
Extend the Product’s Lifespan
The lifespan of electronic components is inversely proportional to their operating temperature. Continuous high temperatures will accelerate material aging, which causes problems such as metal migration and solder joint fatigue. Effective heat dissipation can keep the working temperature within the designed range, which greatly extends the product’s lifespan and reduces the costs of after-sales maintenance and warranty.
In addition, thermal conductive silicone can provide cushioning, shock absorption, moisture-proof and dust-proof functions. In harsh environments such as automotive electronics and outdoor communications, it protects precision components from vibration, moisture and corrosion, which enhances the reliability of products under complex working conditions.
Ensure Safety
For high-power equipment, local overheating may lead to serious safety accidents such as short circuits, fires, and even explosions. Thermal conductive silicone prevents the formation of local overheating by balancing temperature and serves as an important safety barrier. It is particularly suitable for the demanding automotive electronics and aerospace fields.
Conclusion
This article answers the question of whether silicone conducts heat and analyzes the application and importance of thermal conductive silicone from multiple dimensions.
I believe that after reading this article, you have gained a deep understanding of the thermal conductivity of silicone and have had in-depth thoughts on the application of thermal conductive materials in your products.
If you have any other questions about thermal conductive silicone, please contact GALLOP INNOTEK at any time to obtain professional solutions.
