Thermal Interface Materials Apply in LED Lighting

Design challenges encountered in high-power LED lighting solutions are thermal design and thermal protection. A power and thermal management system is required for LED light sources because most of the electrical energy supplied to LEDs is converted to heat compared to other light sources. Without proper thermal management, this heat will affect the LED life and color output. Solving the heat dissipation problem of LED lighting fixtures is an indispensable link in the lighting design.

The thermally conductive materials commonly used in LED lighting fixtures are mainly divided into: structural thermally conductive materials and filling thermally conductive materials according to their functions in the lamps.

In addition to the function of the shell of the lamp, the structural thermal interface material is also used for the heat dissipation of the LED light source, such as thermal conductive plastics. The complementary thermal interface material is mainly used between the heating element and the heat dissipation element, as the connection between the two is used for heat conduction. Since the thermal conductivity of the thermal interface material relative to the heating element and the metal heat sink is low, the choice of the thermal interface material is also very important. Crucially, this determines how fast the heat is transferred.

The following are several thermal interface materials for high-power LED solutions:

Thermal grease: It has the characteristics of excellent thermal conductivity, electrical insulation, use stability, high and low temperature resistance, etc. It is a commonly used thermal conductive material for high-power LED lighting;

Thermal silicone pad: fill the air gap between the heating device and the heat sink or metal base to achieve heat transfer between the heating part and the heat dissipation part, and also play the role of insulation and shock absorption, which can meet the requirements of miniaturization and ultra-thin Design requirements, the ease of use is unmatched by thermal grease;

Thermal adhesive tape: Bonding between the heating sheet and the heat sink is simple and convenient to use, which is beneficial to improve production efficiency.

Potting compound: a room temperature curing one-component silicone adhesive sealant, non-corrosive to most metals; has excellent resistance to cold and heat alternating performance, aging resistance and electrical insulation performance, excellent moisture resistance, Shock resistance, corona resistance, anti-leakage performance.

At present, thermally conductive materials such as thermal conductive grease, thermal pads, thermal double-sided adhesive tape, and potting compound have been widely used in LED lighting solutions; CoolThermo, as a thermally conductive material manufacturer, is committed to providing customers with comprehensive solutions for LED lighting. , to meet customer one-stop purchasing needs.

What Is Thermal Conductive Material? What Is The Different?

When it comes to cooling systems, most people think of fans and heat sinks, often ignoring one of the less visible but important mediators—the thermal conductive material. So, do you know the types of commonly used thermal conductive materials? What are their advantages and disadvantages? We together look!

Thermal gasket

Thermal gaskets are referred to as thermally conductive gaskets. They are used to fill the air gap between the heating element and the heat sink or metal base. Their flexible and elastic characteristics allow them to be used to cover very uneven surfaces. Heat is conducted from discrete components or the entire PCB to the metal enclosure or diffuser plate, increasing the efficiency and lifespan of heat-generating electronic components.
In the use of thermal pad, pressure and temperature are mutually restricted. With the increase of temperature, after the equipment runs for a period of time, the thermal pad material will soften, creep and stress relaxation, and the mechanical strength will also be reduced. down, the pressure of the seal decreases.

Advantage:

(1) Pre-formed thermally conductive material with ease of installation, testing, and reusability;
(2) Soft and elastic, good compressibility, able to cover very uneven surfaces;
(3) It has the effect of buffering, 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, and high cleanliness.

Shortcoming:

(1) The thickness and shape are preset, and the thickness and shape will be limited when used;
(2) The thickness of the thermal pad with a thickness of less than 0.3mm is complex, and the thermal resistance is relatively high;
Application environment: When the gap between the heat-generating component and the heat sink is large, the heat-generating component and the shell conduct heat.

Thermal Grease

Thermal grease, also known as thermal conductive grease, thermal paste, etc., is the most widely used thermal conductive medium at present. An ester-like substance formed after decompression, grinding and other processes, the substance has a certain viscosity and no obvious graininess. It can effectively fill various gaps.

advantage:

(1) Exist in liquid form with good wettability;
(2) Good thermal conductivity, high temperature resistance, aging resistance and waterproof properties;
(3) Insoluble in water, not easy to be oxidized;
(4) It has certain lubricity and electrical insulation;
(5) Low cost.

shortcoming:

(1) It cannot be smeared on a large area and cannot be reused;
(2) The product has poor long-term stability. After continuous thermal cycles, it will cause liquid migration, leaving only the filling material, and the surface wettability will be lost, which may eventually lead to failure;
(3) Due to the different thermal expansion rates of the materials on both sides of the interface, a “gas-filled” effect is caused, resulting in an increase in thermal resistance and a decrease in heat transfer efficiency;
(4) It is always liquid and difficult to control during processing, which is easy to cause pollution to other components and waste of materials, increasing costs.
Application environment: Between the high-power heating components and the radiator, the heat-dissipating components need to have their own fixing devices.

Thermal conductive double-sided adhesive

Thermal conductive double-sided tape is referred to as thermal tape, which is composed of acrylic polymer and silicone adhesive.

Advantage:

(1) It has both thermal conductivity and adhesive properties;
(2) It has good caulking performance;
(3) The appearance is similar to double-sided tape, and the operation is simple;
(4) Generally used for some electronic parts and chip surfaces with less heat generation.

Shortcoming:

(1) The thermal conductivity is relatively low, and the thermal conductivity is general;
(2) It is impossible to glue and fix heavy objects;
(3) Once the thickness of the tape is exceeded, effective heat transfer cannot be achieved with the heat sink;
(4) Once used, it is not easy to disassemble, there is a risk of damage to the chip and surrounding devices, and it is not easy to disassemble completely.
Application environment: It is usually used between a heat source with low power and a small heat sink to fix the LED heat sink, etc.

Thermal Gel

Thermal conductive gel is a gel-like thermal conductive material made of silica gel composite thermal conductive filler after stirring, mixing and potting. This material has some advantages of thermal pad and thermal grease at the same time, and better makes up for the weaknesses of both. Thermal gel inherits the advantages of good affinity, weather resistance, high and low temperature resistance, and good insulation properties of silicone materials. At the same time, it has strong plasticity and can meet the filling of uneven interfaces, and can meet the heat transfer requirements in various applications.

Advantage:

(1) Compared with the thermal conductive gasket, the thermal conductive gel is softer and has better surface affinity, and can be compressed to a very low thickness, which significantly improves the heat transfer efficiency, and can be compressed to 0.08mm;
(2) The thermal gel has almost no hardness, and will not cause internal stress to the equipment after use;
(3) The thermal conductive gel can be directly weighed and used. The commonly used continuous use method is the glue dispenser, which can realize fixed-point quantitative control, save labor and improve production efficiency.

Shortcoming:

(1) The cost is high;
(2) The process is more complicated.
Application environment: between high-power heating components and radiators, it can be used for quantitative control of dispensing machines.

Thermal silica glue ( RTV )

Thermal conductive glue, also known as thermally conductive silica gel, is made of organic silica gel as the main body, adding polymer materials such as fillers and thermally conductive materials, and kneading silica gel, which has good thermal conductivity and electrical insulation properties, and is widely used in electronic components.

Advantage:

(1) Thermal interface material, which will be cured, has adhesive properties and high adhesive strength;
(2) After curing, it is an elastic body, which is resistant to impact and vibration;
(3) The cured product has good thermal conductivity and heat dissipation function;
(4) Excellent high and low temperature resistance and electrical properties.

Shortcoming:

(1) Not reusable;
(2) The caulking gap is general;
(3) The curing time is longer.
Application environment: thermally conductive silica gel can be widely used in various electronic products, the contact surface between the heating body and the heat dissipation facilities in the electrical equipment, which acts as a heat transfer medium and has the properties of moisture, dust, corrosion and shock resistance.

Thermal potting compound

Thermal potting compound is commonly divided into silicone rubber system and epoxy system, silicone system is soft and elastic, and epoxy system is hard and rigid; it can meet the requirements of large depth of thermal conductivity potting. Improve the resistance to external vibration and improve the insulation and waterproof performance between internal components and circuits.

Advantage:

(1) It has a good waterproof sealing effect;
(2) Excellent electrical properties and insulation properties;
(3) It can be disassembled and repaired after curing.

Shortcoming:

(1) The heat conduction effect is general;
(4) The process is relatively complicated;
(5) poor bonding performance;
(6) The cleanliness is average.
Application environment: potting protection of power modules.

Thermally conductive silicone cloth

Thermally conductive silicone cloth is a silicone polymer elastomer reinforced with glass fiber cloth as a base material.

Advantage:

(1) It can effectively reduce the thermal resistance between the electronic components and the heat sink;
(2) Electrical insulation, with high dielectric strength, good thermal conductivity, and high chemical resistance;
(3) It can withstand circuit short circuit caused by high voltage and puncture of metal parts. It is an excellent thermal insulation material to replace traditional mica and silicone grease.

Shortcoming:

(1) The thermal conductivity is not high;
(2) The thickness and shape are preset, and the thickness and shape will be limited when used.
Application environment: filling between heat source and heat dissipation module or shell, insulation filling between live heating element and shell, etc.

Phase change material ( PCM )

Phase change materials refer to substances that change shape with temperature changes and can provide latent heat. The process of a phase change material from solid to liquid or from liquid to solid is called a phase change process.

Advantage:

(1) It can be repaired and reused, and the coating thickness and shape can be controlled as needed;
(2) It is solid at room temperature, but melts to fill the micro-gap during the operation of the equipment (no vertical flow);
(3) The thermal conductivity is equivalent to the traditional thermal grease, with better performance;
(4) Excellent substitute for silicone grease, there is no phenomenon of traditional silicone grease and silicone oil volatilizing, drying and aging.
(5) There is no glue overflow phenomenon of general silicone grease.
(6) Compared with thermal grease, there is no “inflatable” effect, and it has high reliability for long-term use;
(7) It can be dispensed, screen printed, and manually coated, and can be fully automated to greatly increase production;
(8) Environmentally friendly, in line with Rohs standards.

Shortcoming:

(1) It is not easy to store;
(2) Transportation, the cost is relatively high.
Application environment: on the cooling module.

Different thermal conductive materials have their own characteristics. No matter which thermal conductive material is used, there is no way to meet the heat dissipation needs of all electronic devices, and it has more or less some of its shortcomings. The advantages are magnified.

What Is Thermal Adhesive? How To Apply?

Thermal adhesive is a one-component, thermally conductive, room temperature curing silicone adhesive sealant. The condensation reaction of moisture in the air releases low molecules to cause cross-linking and curing, and vulcanizes into high-performance elastomers. Thermally conductive adhesive is also known as silicone thermal conductivity. Glue, thermal conductive silica gel, RTV glue, heat dissipation silica gel, heat transfer glue, heat dissipation glue, cooling glue.

Thermally conductive adhesives can be cured at room temperature and have certain bonding properties. Thermally conductive adhesive is a kind of silicone rubber, which is a one-component room temperature vulcanized liquid rubber. Once exposed to air, the silane monomers in it condense to form a network structure, the system is cross-linked, cannot be melted and dissolved, is elastic, becomes rubbery, and adheres to objects at the same time. And once cured, it is difficult to separate the bonded objects.

Thermal adhesive has good thermal conductivity and high-grade pressure resistance. Its function is to fill the large requirements between the processor and the heat sink. It is the best product to replace the binary heat dissipation system of thermal grease and mica sheet. Thermal adhesive has excellent anti-cold and heat alternating performance, anti-aging performance and electrical insulation performance. And has excellent moisture resistance, shock resistance, corona resistance, leakage resistance and chemical resistance properties. It can be used continuously in the environment of -50 ~ 200 ℃ and maintain performance. Non-swelling and good adhesion to most metallic and non-metallic materials.

Thermal adhesive is a new type of adhesive with fast curing speed, easy extrusion and convenient operation, which can meet any working environment and working conditions. So what are the characteristics of thermal adhesive? In which scenarios is it mainly used? Let’s find out together!

Characteristics of thermal adhesives

  1. No need for screws to fix, reduce the cost of low parts and improve production efficiency; thermal adhesive replaces the traditional card and screw connection;
  2. Because the glue has strong adhesion to the metal surface and is not easy to peel off, it is widely used in the bonding and sealing of PTC sheets and aluminum heat sinks;
  3. Comprehensive contact, providing more effective heat dissipation effect, good operating temperature range -50 ~ 200 ℃, short-term high temperature resistance of 300 ℃;
  4. High dielectric strength to ensure electrical insulation properties; single-component, extremely easy to use;
  5. Elastic bonding, shock-proof, shock-absorbing, can be used in electrical equipment of vibration source;
  6. The bonding speed is fast, the bonding force is strong, and the bonding force is lasting; it is suitable for different product designs and technological processes.

Application of Thermal Adhesive

  1. Mainly used in CPU radiator, heat dissipation between thyristor, chip and heat sink, and heat dissipation of electric iron soleplate;
  2. It is used for heat conduction, heat dissipation and insulation between the heat sink and the CPU. Such as: computers and related equipment, audio-visual sound, electronics, electrical appliances, etc.;
  3. It is used for various high power needs to dissipate heat. Heat transfer related electrical appliances such as: semiconductor refrigeration sheet, water dispenser, electric kettle, TV power amplifier tube and heat sink;
  4. It is used for bonding and heat conduction of high-precision DVD decoder boards, heat conduction of transformers and fixing of electronic components, followed by filling;
  5. The heat dissipation bonding of the LED drive module and the shell; high-power LED flood light, LED street light, LED power supply, LED underwater landscape light, LED point light source, LED indoor downlight, etc. are bonded to the bracket.

The above is the detailed introduction of CoolThermo Technology’s definition, characteristics and functions of thermally conductive adhesives. Only with sufficient understanding of thermally conductive adhesives can we more accurately select the adhesive scheme and achieve better performance in practical applications.

What is a potting compound?

Potting is to pour the liquid basic resin compound into the device with electronic components and circuits mechanically or manually, and then solidify it into a thermosetting polymer insulating material with excellent performance under normal temperature or heating conditions. The liquid base resin compound used in this process is the potting compound.

Electronic thermal potting compound is mainly used for bonding, sealing, potting and coating protection of electronic components. The potting compound is liquid before curing and has fluidity. The viscosity of the glue varies according to the material, performance and production process of the product. The potting compound can realize its use value only after it is completely cured.

There are many types of electronic thermal conductive encapsulants. In terms of material types, the most commonly used three are mainly silicone resin thermal conductive encapsulants, epoxy resin thermal conductive encapsulants, and polyurethane thermal conductive encapsulants. The three material potting compounds can be subdivided into hundreds of different products.

Silicone Thermal Potting Compound

There are many types of silicone potting compounds. Different types of silicone potting compounds have great differences in temperature resistance, waterproof performance, insulation performance, optical performance, adhesion and adhesion to different materials, and softness and hardness. Silicone encapsulants can be added with some functional fillers to give them properties such as electrical conductivity, thermal conductivity, and magnetic conductivity. The mechanical strength of silicone encapsulant is generally poor, and it is precisely this performance that is used to make it “breakable” for easy maintenance, that is, if a component fails, you only need to pry open the encapsulant and replace it with a new one. After the original copy, you can continue to use it.

The color of the silicone potting compound can generally be adjusted arbitrarily according to the needs. or transparent or non-transparent or white color. Silicone potting compound performs very well in shockproof performance, electrical performance, waterproof performance, high and low temperature resistance, and anti-aging performance.
Two-component silicone potting glue (or ab glue) is the most common, and this kind of potting glue includes two types: condensation type and addition type. Generally, the condensation type has poor adhesion to components and potting cavity, and volatile low-molecular-weight substances will be produced during the curing process, and there will be a relatively obvious shrinkage rate after curing. Addition type (also known as silicone gel) has minimal shrinkage and no low-molecular-weight formation during curing. It can be cured quickly by heating.

Advantages: The material of the silicone potting compound is soft after curing. There are two forms of solid silicone rubber products and silicone gels, which can eliminate most of the mechanical stress and have the effect of shock absorption and protection. Physical and chemical properties are stable, with good high and low temperature resistance, and can work for a long time in the range of -50~200 °C. Excellent weather resistance, can still play a good protective role outdoors for more than 20 years, and is not easy to yellow. It has excellent electrical performance and insulating ability. After potting, it can effectively improve the insulation between internal components and lines, and improve the stability of electronic components. With rework capability, sealed components can be taken out for repair and replacement quickly and easily.

Disadvantages: The bonding performance is slightly poor.

Application range: suitable for potting a variety of high-end precision/sensitive electronic devices that work in harsh environments. Such as LEDs, display screens, photovoltaic materials, diodes, semiconductor devices, relays, sensors, automotive ballasts HIV, on-board computer ECUs, etc., mainly play the role of insulation, moisture-proof, dust-proof and shock-absorbing.

Epoxy Thermal Potting Compound

Through the EU ROHS standard, the cured product has high hardness, smooth surface, good gloss, and has the characteristics of fixation, insulation, waterproof, oil-proof, dust-proof, anti-theft, corrosion resistance, aging resistance, and thermal shock resistance. It is used for packaging of electronic transformers, AC capacitors, negative ion generators, aquarium water pumps, ignition coils, electronic modules, LED modules, etc. It is suitable for potting of small and medium-sized electronic components, such as automobile, motorcycle igniter, LED drive power supply, sensor, toroidal transformer, capacitor, trigger, LED waterproof lamp, confidentiality, insulation and moisture-proof (water) of circuit board. Potting.

Advantages: Most epoxy resin potting glues are hard, and a few modified epoxy resins are slightly soft. The major advantage of this material is that it has better adhesion to the material and better insulation, and the cured product has good acid and alkali resistance. Epoxy resin generally has a temperature resistance of 100 ℃. The material can be used as a transparent material with good light transmittance. The price is relatively cheap.

Disadvantages: weak resistance to cold and heat changes, cracks are prone to occur after being impacted by cold and heat, resulting in water vapor infiltrating into electronic components from cracks, poor moisture resistance; colloid hardness after curing is high and brittle, high mechanical stress is easy Strain electronic components; epoxy resin cannot be opened due to its high hardness after potting and curing, so the product is a “lifetime” product, and components cannot be replaced; transparent epoxy resin materials generally have poor weather resistance and light exposure. Or yellowing is easy to occur under high temperature conditions.

Scope of application: Generally used for potting of non-precision electronic devices such as LEDs, transformers, regulators, industrial electronics, relays, controllers, power modules, etc.

Polyurethane potting compound

Polyurethane encapsulant, also known as PU encapsulant, is usually composed of polyols and diisocyanates of oligomers such as polyester, polyether and polydiene, and diol or diamine as chain extenders. to make. Potting compounds can generally be prepared using the prepolymer method and the one-step process.

Polyurethane potting materials are characterized by low hardness, moderate strength, good elasticity, water resistance, mildew resistance, shock resistance, transparency, excellent electrical insulation and flame retardancy, no corrosion to electrical components, and resistance to steel, aluminum, copper, tin and other metals, as well as rubber, plastic, wood and other materials have good adhesion. Potting materials can make installed and debugged electronic components and circuits immune to vibration, corrosion, moisture and dust.

Advantages: Polyurethane encapsulant has excellent low temperature resistance, the material is slightly soft, and has good adhesion to general encapsulation materials, and the adhesion is between epoxy resin and silicone. It has good waterproof, moisture-proof and insulating properties.

Disadvantages: poor high temperature resistance and easy foaming, vacuum defoaming must be used; after curing, the surface of the colloid is not smooth and has poor toughness, and the anti-aging ability, shock resistance and ultraviolet rays are weak, and the colloid is easy to change color.

Scope of application: Generally used for potting of electronic components with low heat generation. Transformers, choke coils, converters, capacitors, coils, inductors, varistors, linear motors, fixed rotors, circuit boards, LEDs, pumps, etc.

Instructions for use of thermal potting compound

  1. Before mixing: A and B components should be fully stirred by hand or machine respectively to avoid changes in performance due to filler settling.​​
  2. Mixing: Weigh the two components according to a certain ratio (1:1, 10:1) and put them into a clean container and stir evenly. The error should not exceed 3%, otherwise it will affect the performance after curing.
  3. Defoaming: natural defoaming and vacuum defoaming, natural defoaming: let the mixed glue stand for 20-30 minutes. Vacuum defoaming: the degree of vacuum is 0.08-0.1MPa, and the vacuum is evacuated for 5-10 minutes.
  4. Perfusion: The rubber material should be perfused within the operating time, otherwise it will affect the leveling. Keep the substrate surface clean and dry before potting. The mixed rubber compound is poured into the device to be encapsulated. Generally, vacuum degassing is not required. If high thermal conductivity is required, it is recommended to vacuum degassing and then pour. (Vacuum defoaming: vacuum degree is 0.08-0.1MPa, vacuuming for 5-10 minutes)
  5. Curing: It can be cured at room temperature or by heating. The curing speed of the glue has a lot to do with the curing temperature. It takes a long time to cure in winter. It is recommended to use heating to cure. It takes 15-30 minutes to cure at 80 °C, and it generally takes about 6-8 hours to cure at room temperature.

With its excellent performance, thermal potting compound can well meet the needs of the consumer market, ensure effective bonding, sealing, potting and coating protection between electronic devices and products, and better bring high-quality insulation to the electronics industry. materials, so as to effectively improve its product awareness, so that more areas of awareness, effective use.

What is Silicone Adhesive?

Speaking of “adhesive”, many people may be at a loss, and to put it another way “glue”, suddenly realized. Professionally known as adhesives, the range of adhesives is too wide and has been widely used in aerospace, aircraft manufacturing, electronics industry, machining, automobile manufacturing, construction and medical care. Adhesives are used in everything from food, clothing, housing and transportation to aerospace. Silicone is one of them.

Silicone? What is Silicone? Organosilicon compounds refer to compounds that contain Si-C bonds and at least one organic group is directly connected to a silicon atom. It is also customary to use those compounds that connect organic groups to silicon atoms through oxygen, sulfur, nitrogen, etc. Also used as organosilicon compounds. Among them, the polysiloxane composed of silicon-oxygen bond (-Si-O-Si-) as the skeleton is the most numerous, the most deeply studied and the most widely used type of organosilicon compounds, accounting for more than 90% of the total dosage. .

The silicone adhesive is a one-component, translucent paste-like room temperature curing adhesive, which is a high-performance elastomer that is naturally cured. It has excellent heat and cold resistance, aging resistance and electrical insulation properties, and has good adhesion to most metal and non-metal materials.

Silicone adhesives can be divided into two categories: silicone resin-based adhesives and silicone rubber-based adhesives. The chemical structures of the two are different: the silicon-oxygen bond is the main chain of the body structure, which can be further condensed into a high-strength cross-linked hard and brittle resin at high temperature; while silicone rubber is a linear silicone rubber. A relatively high molecular weight elastomer with oxygen bonds as the main chain. The relative molecular weight ranges from tens of thousands to hundreds of thousands, and they must be condensed into elastomers with several cross-linking points under the action of curing agents or catalysts. It can also be divided into two types: condensation type and addition type. The addition type is a silicone adhesive made of cyanopolysiloxane and vinyl polysiloxane as the main material under the action of a catalyst.

Compared with other types of polymer materials, what are the excellent properties of silicone adhesives?

The basic structural unit of silicone products is composed of silicon-oxygen chains, and the side chains are connected to various other organic groups through silicon atoms. Therefore, the structure of silicone products contains both “organic groups” and “inorganic structures”. This special composition and molecular structure make it combine the characteristics of organic substances with the functions of inorganic substances.

Compared with other polymer materials, the most outstanding properties of silicone adhesives are:

  1. Temperature resistance

The silicone adhesive is based on a silicon-oxygen (Si-O) bond as the main chain structure. The bond energy of the C-C bond is 82.6 kcal/mol, and the bond energy of the Si-O bond is 121 kcal in silicone. /molecule, so the thermal stability of the silicone adhesive is high, and the chemical bonds of the molecules are not broken or decomposed under high temperature (or radiation irradiation). Silicone adhesives are not only resistant to high temperatures but also low temperatures, and can be used in a wide temperature range. Whether it is chemical properties or physical and mechanical properties, the change with temperature is very small.

  1. Weather resistance

The main chain of the silicone adhesive is -Si-O-, and there is no double bond, so it is not easy to be decomposed by ultraviolet light and ozone. Silicone adhesives have better thermal stability, radiation resistance and weather resistance than other polymer materials. The service life of silicone adhesives in natural environment can reach several decades.

  1. Electrical insulation properties

Silicone adhesives all have good electrical insulation properties, and their dielectric loss, withstand voltage, arc resistance, corona resistance, volume resistivity and surface resistivity are among the best in insulating materials, and their electrical properties are affected by temperature and frequency. impact is small. Therefore, they are a stable electrical insulating material and are widely used in the electronics and electrical industries. In addition to excellent heat resistance, silicone adhesives also have excellent water repellency, which enables electrical equipment to be used in wet conditions with high reliability.

  1. physiological inertia

Polysiloxanes are among the most inactive compounds known. They are very resistant to biological aging, have no rejection reaction with animals, and have good anticoagulant properties.

  1. Low surface tension and low surface energy

The main chain of the silicone adhesive is very flexible, and its intermolecular force is much weaker than that of hydrocarbons. Therefore, it has lower viscosity, weaker surface tension, lower surface energy, and stronger film-forming ability than hydrocarbons of the same molecular weight. This low surface tension and low surface energy are the main reasons for its many applications: hydrophobicity, defoaming, foam stabilization, anti-sticking, lubrication, glazing and other excellent properties.

It is these excellent properties of silicone adhesives that are widely used in military/aerospace/construction/electrical/electronics/automobile/leather/textile/chemical/medical and medical industries.

What is the difference between one-component thermal gel and two-component thermal gel?

Thermal gel can be widely applied to various electronic products, the contact surface between the heating element and the heat dissipation facility in the electrical equipment, as a heat transfer medium and has the properties of moisture-proof, dust-proof, corrosion-proof and shock-proof. Thermal gel can be divided into one-component thermal gel and two-component thermal gel according to functional applications. What is the difference between one-component thermal gel and two-component thermal gel? We together look!

One-component thermal gel

One-component thermal gel belongs to room temperature curing silicone rubber. It is a one-component electronic thermally conductive thermal gel that is mainly made of silicone and refined from high-quality thermally conductive materials, fillers and other polymer materials. It releases low molecules through condensation reaction with moisture in the air to cause cross-linking, and vulcanizes into a high-performance elastomer. After complete curing, it has excellent resistance to high and low temperature changes, and will not reduce heat dissipation due to contact gaps after components are fixed. .

One-component thermal gel has excellent thermal conductivity and heat dissipation performance, as well as excellent electrical properties, aging resistance, anti-cold and heat alternating performance, moisture resistance and non-swelling, electrical insulation performance, power decay rate, shock resistance, waterproof, vibration absorption and Stability increases the safety factor of electronic products during use. It has excellent bonding strength to electronic components, PVC, plastics, etc., as well as excellent sealing and thermal conductivity.

One-component thermal gel is easy to use and operate, and can be applied manually or mechanically, without leakage of glue, which can meet a variety of working environments and working conditions, and has the performance of simple and convenient gluing; one-component thermal gel is a kind of Non-toxic, non-polluting products, safer and more environmentally friendly.

Two-component thermal gel

Two-component thermal gel is used as a heat transfer medium for cooling electronic devices, and can be cured into a soft elastomer in situ without stress to electronic components. After curing, it is closely attached to its contact surface to reduce thermal resistance, which is more conducive to the heat conduction between the heat source and its surrounding heat sinks, motherboards, metal shells and shells.

Two-component thermal gel has the advantages of high thermal conductivity, good insulation performance and easy to use. Two-component thermal gel is generally divided into two categories: condensation type and addition type.

Condensed type

Usually A:B is a weight ratio of 10:1. Main advantages: good adhesion, relatively soft. Disadvantages: slow curing time and poor thermal conductivity.

Addition

Usually A:B is a weight ratio of 1:1, the higher the temperature, the faster the curing, the main advantage: the solid is softer and protects the electronic device more. Disadvantages: poor adhesion.

The difference between one-component thermal gel and two-component thermal gel

  1. The one-component thermal gel does not absorb or release heat during curing. After curing, the shrinkage rate is small, and the adhesiveness to the material is good, but it is not easy to carry out secondary repair. The two-component thermal gel has elasticity after curing, and can be Repair an area.
  2. One-component thermal gel does not need to configure the ratio of silica gel to curing agent. The curing agent is already added to the silica gel. The operation process is simple, no mixing or defoaming operation is required, just extrude the tube container, two-component Thermal silica requires that components A and B will not gel quickly after mixing, so they have a long operating time.
  3. One-component thermal gel is only suitable for small-area potting, and the thickness should not exceed 6mm. Two-component thermal gel is more suitable for large-area potting operation. It has low viscosity and good fluidity, and is suitable for molding complex electronic parts.

Through CoolThermo’s introduction to the characteristics and differences of one-component and two-component thermal gel, do you have more knowledge about thermal gel?

What Is RTV Adhesive? What Are The Characteristics Of RTV Glue?

RTV adhesive is a room temperature vulcanized silicone rubber adhesive, RTV is the abbreviation of English (Room Temperature Vulcanized Silicone Rubber), a silicone rubber that can be vulcanized at room temperature. Silicone rubber is a straight-chain high-molecular-weight polysiloxane with a molecular weight of more than 150,000. Its structural form is similar to that of silicone oil. Usually, both ends of its molecular chain contain active groups such as hydroxyl and vinyl. Low.

RTV adhesive is prepared by compounding components such as silicone rubber, cross-linking agent and filler. There are two kinds of one-component RTV adhesive and two-component RTV adhesive. RTV silicone glue has a long storage period and stable performance. It can bond common metal and non-metal materials, so it is suitable for bonding and sealing between various metals and between metal and non-metal materials.

Introduction to The Characteristics of RTV Silicone Glue

  1. After curing, the RTV silicone glue thermal gel presents an elastic colloid. The elastic colloid can play a protective role when it vibrates and is not easy to break.
  2. RTV silicone glue is more convenient to vulcanize. Whether it is a one-component product or a two-component product, it can be vulcanized at room temperature. It can be cured without heat treatment, and it will not shrink or release toxic substances after curing. , performance safety is guaranteed.
  3. RTV glue also has the characteristics of long-term storage resistance. The shelf life is 12 months. During the storage period, as long as there is no air or moisture, the performance is the same as before, and the bonding strength is strong.
  4. The reason why RTV glue thermal gel can be used in electrical appliances is that it has good electrical insulation properties after curing. It is suitable for -60 ℃ ~ 200 ℃ working temperature, can meet the electrical insulation requirements, and is safer to use, even if the electrical appliance is short-circuited , and will not cause a fire.
  5. RTV gel glue has a wide range of applications, not only for bonding and fixing electrical components, but also for bonding electrical or electronic instrument housings. After curing, the waterproof performance is very good, and it will not change after many years of use.
  6. RTV silicone glue does not have any corrosiveness. Although RTV silicone is a kind of adhesive, it will not corrode metal, ceramics, plastics and circuits after curing, and it has no effect on the human body. For this, big brand products Do better, such as CoolThermo, focus on the research of rtv silicone glue, provide customized rtv silicone glue application solutions, widely used, can be used in new energy, military, medical, aviation, ships, electronics, automobiles, instruments , power supply, high-speed rail and other industries.

RTV silicone glue is now an indispensable material in the manufacturing process of electrical appliances, electronics, automobiles, instruments and other fields. If the construction volume is large, it can be purchased in large quantities, as long as you pay attention to storage.

Can white oil be added to the potting compound? What are the effects of white oil-doped silicone electronic potting compounds?

The price of silicone electronic potting glue in the market is high and low, and the price of some electronic potting glue is far lower than the average market price. Why? Is their technology advanced and can effectively control production costs? In fact, the reason is that they add low-cost white oil to the potting compound material, which controls costs and disrupts the market.

What is white oil?

White oil, also called white mineral oil, is a special deep-refined mineral oil. Transparent, colorless, odorless, chemically inert, the basic substances are saturated hydrocarbons, aromatic hydrocarbons, etc., and the molecular weight is usually between 250 and 450. The boiling point is generally within 150 °C. It is widely used in daily chemical, pharmaceutical, food, rubber and plastic, agriculture and other industries.

Why does adding white oil reduce production costs?

Because the price of white oil is relatively low. For example, the general market price of silicone oil is 30 yuan/kg, while the price of white oil is only 10 yuan/kg. On the premise of ensuring the acceptance quality of electronic potting glue, 20% white oil can be added, then doping The glue cost of white oil is 26 yuan/kg. In this way, by adding an appropriate proportion of white oil, the price of electronic potting glue can be reduced and the potting glue market can be seized.

What is the effect of electronic potting compounds with added white oil?

We know that silicone oil is a polymer material with a siloxane structure and has organic and inorganic properties, while white oil is an organic polymer with a carbon structure and has no inorganic properties. Since white oil is chemically inert, it does not participate in the cross-linking reaction of organic silica gel.

When the silicone is cured, the free white oil slowly seeps out of the glue. Once the electronic potting compound doped with white oil is used on electronic products such as driving power supply, the following situations may occur:

  1. Various physical properties are poor, such as tensile strength and tear strength will decrease;
  2. The ability of heat dissipation and flame retardancy is poor, and it is difficult to effectively improve the heat dissipation capacity and safety factor of electronic products, which is prone to accidents;
  3. Poor high and low temperature resistance, poor weather resistance, and easy cracking of the colloid, allowing rainwater to penetrate into the electronic components from the cracks, reducing the moisture-proof ability of electronic products, and causing electronic components to fail;
  4. The electrical performance and insulation ability are poor, which affects the anti-electromagnetic interference ability of electronic components after potting, and is prone to failure.

How to detect whether white oil is added to electronic potting compound?

Since the boiling point of white oil is relatively low, less than 150 °C, and the boiling point of silicone oil is around 200 °C, the simple method in the laboratory is to test the volatile content of the uncured or cured potting compound. The test method is: oven at 150 °C After baking for 3 hours, the weight difference after volatilization was measured. The volatile matter of normal electronic potting glue is less than 1%, and the volatile matter of added white oil is greater than 5%. When the volatile content is abnormally high, it can be judged that white oil is added to the electronic potting compound.

In short, when we choose electronic potting glue, we can’t blindly covet cheap prices, we must consider the comprehensive selection of product quality and company services.

How To Apply Thermal Gel?

Thermal gel is currently a widely used heat dissipation product in the electronics industry. This product is mainly used in low-power heating devices, which can prevent electronic devices from overheating and malfunction for a long time. However, when many electronic industries are using thermal gel products, they are often not familiar with the performance of the products, so there are often some ridiculous low-level misoperation problems.

Different products have certain differences in the method of use. We must have the correct operation method in the process of use. These are very important to all of us, so how to correctly operate in normal times? What about using thermal gel? This is also a concern of many people. If you can have a better understanding of these aspects in advance, the subsequent use will be easier.

Before using the thermal gel, we must do a good job of surface treatment, remove those vivid substances that exist on its own surface, and do a good job of polishing through a variety of different methods, so as to improve the repaired surface as soon as possible. This kind of roughness can be properly scrubbed and cleaned with some reagents during use, so that the surface will be cleaner. In the process of application, the surface can be glued, so that it can really ensure that the color is uniform and must be used within the specified time.

After the surface treatment is done, we must apply it. When applying it, it should be relatively uniform. At the same time, we must also do a good job of anti-negative pressure, so as to ensure better filling of the material and achieve better results. If you need multiple layers of glue When using it, you should do some treatment on the surface, and then do some smearing work. During the application process, you must pay attention to the specific temperature. At the same time, you should also pay attention to the correct use method. Gel storage works.

What Is The Role Of Adhesives In Car? Application Analysis Of Adhesives In Automobile Manufacturing Industry?

The demand for automotive adhesives and sealants is growing rapidly. Adhesives and sealants for automobiles are an important auxiliary material for automobile production. With the development of automobiles in the direction of lightweight, high-speed energy saving, safety and comfort, low cost, long life and pollution-free applications are becoming more and more important.

In terms of glues for automobile manufacturing, the average dosage of organic silica gel is 300g/vehicle, the average dosage of polyurethane glue is 900g/vehicle, acrylate is 66g/vehicle, and anaerobic adhesive is 120g/vehicle; The average amount of silica gel is 60g/vehicle, and the average amount of polyurethane glue is 40g/vehicle.

The application of adhesives and bonding technology in automobile manufacturing can not only enhance automobile structure, fasten rust prevention, heat insulation and vibration reduction, interior and exterior decoration, etc., but also replace traditional processes such as welding and riveting in certain parts, simplify production processes and optimize products. structure. Therefore, adhesives play an increasingly important role in the lightweight, energy saving and consumption reduction of automobiles, prolonging service life and improving performance.

From the perspective of the working parts and functions involved in the entire automobile manufacturing process, automotive adhesives can be roughly divided into adhesives for welding processes, adhesives for painting processes, adhesives for interior parts, adhesives for assembly parts, and special adhesives. Craft glue and other five categories.

Adhesive parts for automotive applications

  1. Seat pressure sensor
  2. Car lights
  3. Car antenna
  4. Filter
  5. Door sensor
  6. Door switch
  7. Rearview mirror
  8. Ignition module
  9. Harness
  10. Car anti-theft coil
  11. Electronic accessories
  12. Tire pressure sensor
  13. Seat heating device
  14. Car remote control
  15. Seat belt sensor

Among them, the glue for welding process is mainly used to replace spot welding or reduce welding points, and play the role of strengthening structure, sealing and rust prevention, vibration reduction and noise reduction. Its main varieties are:

Hemming adhesive: It is used in crimping structures such as doors, hoods, and trunk lids. It has high bonding strength and has completely replaced spot welding structures. One-component epoxy resin is generally used for this kind of glue, and the dosage for a bicycle is about 200g;

Spot welding sealant: It is pre-applied on the overlapping parts of the steel plate welding, and the gap is filled after spot welding to ensure sealing and prevent rust. For those parts that are masked after assembly and difficult to apply weld sealant, spot welding sealant is even more indispensable;

Expansion damping glue: This kind of glue is often used between the inner and outer panels of the door, between the outer body cover and the reinforcing ribs. It is generally made of synthetic rubber or resin and combined with a foaming agent. After curing and expansion, the cover can be combined with the reinforcing rib to play the role of vibration reduction and noise reduction.

There are not many varieties of glue used in the coating process, but it is the most used type in automobiles. Among them, the truck is about 2kg, and the car is more than 5kg. It is mainly used for automobile sealing, leakage prevention, rust prevention and buffering of sand and gravel to the chassis when the car is running at high speed. impact and reduce the noise in the car, such as pvc plastisol and its modified products.

Adhesives for interior parts are mainly used in body roof, door inner panel waterproof membrane and windshield lining, etc., to increase the beauty of the car, enhance the rigidity of the body, and seal, such as neoprene, butyl, and polyurethane glue. Wait.

The glues used for assembly parts mainly include anaerobic glue, silicone sealant, etc., which are mainly used in the assembly of automobile engines, gearboxes and chassis.

In addition, in the process of automobile manufacturing, some special process adhesives, such as phenolic resin adhesive used for the bonding of brake shoes and friction linings, are also used, which can replace riveting and have reliable bonding strength, which can reduce noise and prolong friction lining. Service life and other functions; the pressure-sensitive tape used in the car assembly process can protect the car itself from pollution, bump damage, or assist in fixing and positioning when assembling parts.

With the development of the automotive industry, automotive adhesives are developing rapidly from variety to output. The automotive industry has high requirements for the quality, performance and safety of adhesives. Domestic adhesive products are relatively backward and have a single variety, which is difficult to meet the demand. It is necessary to import a large number of high-quality and high-performance adhesives. Therefore, efforts to develop high-quality, high-performance adhesives to meet the needs of the automotive industry are expected to yield high returns. The market demand for automotive adhesives is promising.

Language »