1. Source of silicone:

　　Mineral silica silicone silicone oil, silicone grease, gel, rubber, resin

　　2. Silicone characteristics:

　　1. Excellent dielectric properties: high dielectric strength, high dielectric resistivity, low dielectric constant.

　　2. Excellent temperature resistance: -50℃ (-100℃) ~ 200℃.

　　3. High stability, low application, soft at low temperature and stable at high temperature.

　　4. Water repellent, low hygroscopicity.

　　5. Weather-resistant, resistant to radiation, ozone and arc, clear and transparent.

　　6. Environmentally friendly, low toxicity, non-corrosive.

　　7. Repairable.

　　3. Application of silicone in electronic assembly: insulating coating, adhesion and sealing, potting, thermal conductivity:

　　1. Insulating coating

　　①Ideal conformal coating: a One-component b Low viscosity c Suitable for spraying, dip coating, selective or flow coating d Long pot life e Fast curing, no cured products f Can also be cured under the component g Can be repaired h Wide applicable temperature i No toxicity j Low cost k Strong adhesion.

　　②Why use conformal coating: a. To protect circuit boards and prevent short circuits and conductor corrosion caused by moisture and contamination. b. Moisture will accelerate corrosion and electron migration between conductors, and will cause damage to uncoated circuit boards. Damage c Scratch d Mechanical and thermal applications e Solvents f Stains g Insects and animals h Maintain the insulation of circuit boards.

　　③ Types of conformal coatings: acrylic resin, epoxy resin, polyurethane resin, parylene, silicone physical property advantages. Acrylic resin has good electrical properties, is hard, has good mechanical strength, is transparent, and is resistant to UV light. Poor solvent resistance, low thermal stability, flammable, medium cost and high unit price epoxy resin with excellent electrical properties, strong mechanical strength, strong adhesion, strong chemical resistance, high temperature for heating and curing, medium price, average thermal stability, curing It releases a lot of heat when curing, shrinks when curing, has poor oxidation resistance, and contains toxic ingredients. When the flexibility increases, the electrical properties and temperature resistance will decrease. Polyurethane resin has good electrical insulation, strong mechanical strength, toughness and wear resistance, and strong adhesion. , resistant to thermal shock, good low-temperature stability, medium softness to hardness, medium price, poor high-temperature stability, sensitive to water vapor and most solvents, not resistant to UV light, contains toxic ingredients, flammable polyparaxylene is resistant to micro pinholes Excellent coverage, low gas release, can form thin layer coating, general mechanical strength, medium to high unit price silicone has excellent electrical properties, very stable at high and low temperatures, can provide products with different hardness from soft gel to hard resin. Water-based, anti-oxidation, anti-UV, anti-thermal shock, low toxicity, good chemical stability, general mechanical strength, medium to high unit price.

　　④Conformal coating: a. Generally apply 3-5mil by dip coating or spraying or flow coating. b. Prevent the circuit board from being corroded by outgassing, pollution and other harsh environments. c. Provide stress buffering for the circuit board. The basic coating is: single group Points, low viscosity, outgassing curing at room temperature or rapid curing by heating.

　　⑤Coating process: a Dip coating method (often used) b Spray coating method (often used) c Selective coating method d Flow or brushing method (less commonly used).

　　2. Adhesion and sealing

　　①Adhesion: Use adhesive to bond and seal two objects: Use sealant to fill the gap.

　　②Characteristics: a. Excellent electrical properties, b. Moisture-proof and weather-resistant, c. Stable at high temperatures, soft at low temperatures, d. Low stress.

　　③Typical adhesives: a. One-component; b. Cured by outgassing at room temperature or cured quickly by heating; c. Soft and able to provide application cushioning.

　　④The operating process of adhesives and sealants: a. Surface cleaning, b. Selecting a suitable primer, c. Applying glue, and d. curing.

　　⑤Cure types of adhesives and sealants:

　　A. Comprehensive curing RTV: a One-component deacidification type b One-component detungstenization type c One-component dealcoholization type d Two-component dealcoholization type.

　　B. Heating type and heat curing type: a single component b two components.

　　⑥Classification of silicone adhesives and sealants:

　　A. One-component comprehensive curing RTV: a. Moisture curing, b. Suitable for curing in open environment, c. Suitable for thinner coating layers.

　　B. Two-component comprehensive curing RTV: a. No moisture is required during curing. b. Suitable for dry curing in an open environment. c. Suitable for thicker adhesive layers.

　　C. One-component addition type thermal curing: a. No moisture is required during curing. b. Can be cured in a closed environment. c. Applicable to any thickness of adhesive layer. d. Must be heated for curing.

　　D. Two-component addition type thermal curing: a. No moisture is required during curing. b. Can be cured in a closed environment. c. Applicable to any thickness of adhesive layer. d. Must be heated for curing.

　　E. Primer: Improve the adhesion of the adhered surface by the chemical force between adhesives.

　　Surface cleaning: a. The adherend must be clean and dry; b. Clean with appropriate solvent; c. Avoid further contamination.

　　3. The function of potting glue is to protect components and modules: a. Provide insulation protection; b. Isolate pollution; c. Reduce stress damage to components.

　　①Elastic potting material provides conformal coating-like protection. Typical potting materials are: a two-component b products with different hardness c transparent or opaque d room temperature curing or rapid thermal curing.

　　②Gel potting material:

　　a After curing the gel material provides excellent stress protection.

　　b After curing, the gel material is very soft and remains sticky, and can adhere to a variety of material surfaces.

　　c Most gels are clear and transparent materials.

　　Typical gel materials are: a two-component b clear and transparent c low viscosity d cured at room temperature or heated.

　　③Operation process of potting materials: Mix according to the proportion, defoaming, potting and solidification.

　　4. Heat conduction

　　①Overview of thermally conductive materials

　　a The heat generated by electronic components needs to be conducted to the heat sink through an appropriate medium on the interface, and then dissipated to the surrounding environment.

　　b In order to achieve the heat dissipation effect, the dielectric material not only needs to have thermal conductivity, but also needs to have good coverage on the rough component surface.

　　② Where thermally conductive materials are used: a. From the chip to the wires and the package inside the microprocessor; b. From the microprocessor to the heat sink; c. From the heat sink to the surrounding environment.

　　③Electrical properties of thermal conductive materials: Silicone materials themselves have excellent electrical properties. Silicone materials with thermal conductivity still maintain excellent electrical properties including: a dielectric strength b dielectric constant c volume resistivity.

　　④ Thermal conductive products and technologies: a Thermal conductive silicone adhesive b Thermal conductive silicone potting materials and sealing materials c Thermal conductive silicone gel d Thermal conductive silicone grease.

　　a Thermal conductive silicone adhesive.

　　A. Definition: A one-component or two-component adhesive that increases thermal conductivity by adding appropriate fillers.

　　B. Typical applications: The most typical use is to bond a small heat sink to a heat dissipation component to replace mechanical fixation. It is especially suitable for bonding rough surfaces.

　　b Thermal conductive silicone potting materials and sealing materials.

　　A. Definition: A thermal conductive material composed of silicone oil and fillers.

　　B. Typical applications: Thermal conductive silicon is the earliest widely used thermal conductive material and has low interface thermal resistance.

　　c Thermal conductive silicone gel.

　　A. Definition: A thermally conductive organic silica gel with low elastic modulus.

　　B. Typical applications: Mainly used for heat conduction in situations where the distance between components or devices is large.

　　d Thermal conductive silicone grease.

　　A. Definition: A lightly cured, low elastic modulus, organic silica gel containing thermally conductive fillers. The fillers can be electrically conductive or electrically conductive or electrically insulating fillers.

　　B. Typical applications: heat conduction when used in situations where it must have high conductivity, low interface thermal resistance and can form coverage on rough surfaces.

　　⑤Comparison of thermal conduction technology with other thermal conduction technologies.

　　A. Silicone has better wettability and can improve contact and thermal resistance.

　　B. Wet type coatable materials can achieve economical, automated and mass production.

　　C. Silicone is more thermally stable than other organic materials.

　　D. The low elastic modulus of silicone can provide better stress relief between components.

　　E. Silicone is sticky, which eliminates the need for mechanical fixation (compared to thermal sheets).

　　4. Classification of electronic silicone in the electronics industry.

　　1. Conformal coating;

　　2. Elastic potting material;

　　3. Gel potting materials;

　　4. Adhesive;

　　5. Thermal conductive glue;

　　6. Others;

　　5. Application of electronic silicone in the electronics industry;

　　1. Power supply

　　①Features:

　　A. Mainly used in computers (laptops, servo systems) and communications industries.

　　B. AC-DC SPS/DC-DC SPS.

　　C. More than 80% of the product power range is less than 300W.

　　D. More than 60% of the industry is ODM/OEM.

　　E. Industry products tend to be smaller and more efficient.

　　F. Requires bonding and potting glue, and heat dissipation requirements are getting higher and higher.

　　②Silicone application

　　A. Passive components are fixed;

　　B. Power component heat dissipation;

　　C. AC-DC/DC-DC converter potting;

　　2. Printed circuit board assembly line—coating

　　①Instrument control: servo network card, LED control panel, LCD display module, security alarm, lighting, electronic scale, water heater control panel, transformer coil...

　　②Wireless communication: module, indoor cordless radio frequency...

　　③Automotive electronics: instruments, alarms, audio and video systems, controller fans...

　　④Consumer electronics: remote controls, toy LCD modules, audio and video systems...

　　3. Communication system

　　①System and component/module manufacturing (coating, potting, bonding, thermal conductivity);

　　②LCD—TAB/COG;

　　③Battery;

　　4. LCD display

　　①LCD module

　　A. TN: Most do not use silicone;

　　B. STN: It is likely to use silicone, especially colored STN;

　　C. TFT: all made of silica gel;

　　D. COB: No silica gel is used;

　　E. TAB;

　　F. COG: Use FPC to connect;

　　G. COF.

　　②Related applications—touch screen (fluid bonding)

　　5. Light-emitting diode display LED

　　①LED backlight

　　A. Bonding;

　　B. Potting;

　　②LED display (outdoor or color)

　　potting;

　　coating;

　　6. Plasma display PDP

　　①Display PANEL (no silicone required);

　　②Display module MODULE;

　　A. Flexible printed circuit (FPC) reinforcement;

　　B. Components are fixed;

　　C. Coating;

　　D. Module heat dissipation.