Electronic potting compound is a broad term. Used for bonding, sealing, potting, and coating protection of electronic components. Before curing, the potting material is liquid and has fluidity. The viscosity of the adhesive varies depending on the material, performance, and production process of the product. Its practical value can only be realized after complete curing, which can play a role in waterproofing, moisture-proof, dust-proof, insulation, thermal conductivity, confidentiality, corrosion resistance, temperature resistance, and vibrate resistance. At present, there are many types of electronic potting compound on the market. According to the material type, the three most commonly used ones are epoxy resin potting material, organic silicone potting compound, and polyurethane potting compound. The selection of potting material will directly affect the precision and timeliness of electronic products. Among the many types of potting materials, how to choose a suitable potting material for enterprise products has become a technical difficulty. Below, we will introduce the advantages and disadvantages of these three types of potting material, as well as their main uses in the current market.
1. Epoxy Resin
Advantages: Epoxy resin potting material is mostly hard. The major advantages of this material are its good adhesion to the material and good insulation. The cured material has good water resistance, acid and alkali resistance. Epoxy resin generally has a temperature resistance of 100 ℃. The material can be used as a transparent material with good transparency.
Disadvantages: Weak resistance to cold and hot changes, prone to cracking after being subjected to cold and hot shocks, resulting in water vapor seeping into electronic components from the cracks and poor moisture resistance; After curing, the colloid has high hardness and brittleness, and high mechanical stress can easily strain electronic components; Once the epoxy resin is sealed and cured, it cannot be opened due to its high hardness, so the product is a “lifetime” product and cannot be replaced with components; Transparent epoxy resin materials generally have poor weather resistance and are prone to yellowing under light or high temperature conditions.
Application scope: potting of non precision electronic devices such as transformers, regulators, industrial electronics, relays, controllers, power modules, etc.
2.Silicone
Advantages: The silicone potting adhesive is soft after curing, and has two forms: solid rubber and silicone gel, which can eliminate most of the mechanical stress and have the effect of vibrate absorption protection. Stable physical and chemical properties, with good resistance to high and low temperatures, can work for a long time in the range of -50~200 ℃. Excellent weather resistance, able to provide good protection outdoors for more than 20 years, and not prone to yellowing. It has excellent electrical performance and insulation ability, effectively improving the insulation between internal components and circuits after potting, and improving the stability of electronic components. With the ability to repair, sealed components can be quickly and conveniently removed for repair and replacement.
Disadvantages: Poor bonding performance, poor water resistance, and low material hardness, which are not suitable for potting shell components.
Application scope: Suitable for potting various high-end precision/sensitive electronic devices that work in harsh environments. Such as LEDs, display screens, photovoltaic materials, diodes, semiconductor devices, relays, sensors, automotive stabilizers HIV, on-board computer ECUs, etc., mainly play a role in insulation, moisture prevention, dust prevention, and vibrate absorption.
3.Polyurethane
Advantages: Polyurethane potting adhesive, also known as PU potting adhesive, is generally a two-component material consisting of a main agent and a curing agent. Polyurethane adhesive has good bonding performance, insulation performance, and weather resistance, and is mainly used in various electronic and electrical equipment that need to be packaged. The characteristics of polyurethane potting materials are adjustable hardness, moderate strength, good elasticity, water resistance, fungus proofing, vibrate resistance, transparency, excellent electrical insulation and flame retardancy, no corrosion to electrical components, good adhesion to metals such as steel, aluminum, copper, tin, as well as materials such as rubber and plastic.Potting materials can protect installed and debugged electronic components and circuits from the effects of vibration, corrosion, moisture, and dust.
Polyurethane potting materials are different from epoxy resin potting and organic silicone resin potting in the electronics industry. They overcome the drawbacks of commonly used epoxy resins such as brittleness, yellowing, and high internal stress, as well as the low strength, poor adhesion, and poor water resistance of organic silicone resins. They have excellent water resistance, cold resistance, UV resistance, acid and alkali resistance, high and low temperature impact resistance, moisture resistance, environmental protection, and high cost-effectiveness. They are ideal potting and protection materials for electronic components. Polyurethane potting, which comprehensively meets the requirements of flame retardant V0 level (UL), environmental protection certification (SGS) and other certifications, is developed for the long-term protection of precision circuit controllers and components in the electronic industry. It has excellent electrical insulation and is particularly suitable for potting electronic circuit boards and components used in harsh environments such as humidity, vibration, and corrosive environments. Suitable for potting various electronic components, microcomputer control boards, etc., such as pulse igniters, washing machine control boards, electric bicycle drive controllers, etc.
Disadvantages: The ability to withstand high temperatures is not strong, and it is prone to foaming, so vacuum defoaming must be used.
Application scope: Generally used for potting electronic components with low heat generation. Transformers, anti current coils, converters, capacitors, coils, inductors, variable resistors, linear engines, fixed rotors, circuit boards, LEDs, pumps, etc.
