How To Select Electical and Electronic Resins

Electrical and electronic resins are adhesives, greases, pads, stock shapes, tapes, encapsulants, potting compounds, thermal interface materials, and electrically conductive substances used in electrical, electronic, and semiconductor applications. There are several basic types of electrical and electronic resins. Electrically conductive products provide low resistivity and are often used to prevent electrostatic discharge (ESD), electromagnetic interference (EMI), and radio frequency interference (RFI). They are also used in thick film metallization and to provide electrical interconnections at both the device and circuit board level. Thermally conductive electrical and electronic resins are applied between a heat-generating electrical device and a heat sink in order to improve heat dissipation. These products form a thermally conductive layer, either between components or within a finished product. Thermal interface materials that use a phase change are also available. 

Chemical Systems And Filler Materials

Electrical and electronic resins use many different chemical systems and filler materials. Some chemical systems contain acrylics, elastomers, natural or synthetic rubbers, epoxy resins, water-based resins, silicone compounds, or volatile organic compounds (VOCs). Others contain bismaleimide (BMI) resins, phenolics, formaldehyde resins, cellulosic thermoplastics, liquid crystal polymers (LCPs), or vinyl compounds. Commonly used chemical systems include polyamide, polybutadiene, polycarbonate (PC), polyolefin, polypropylene (PP), polysulfide, and polyurethane (PUR). In terms of filler materials, some electrical resins and electronic compounds include aramid fiber, chopped fiber, carbon powder, or graphite powder. Other products contain glass fillers, metal fillers, or inorganic compounds. Unfilled electrical and electronic resins are also available. There are several curing technologies for electrical and electronic resins. Typically, thermoplastics and hot melt adhesives are cured using heat or heat and pressure. Vulcanization, a thermosetting reaction, uses heat and/or pressure in conjunction with a vulcanizing agent to produce materials with greatly increased strength, stability, and elasticity. Some products cure or vulcanize at room temperature. Others cure with radiation, electron beam irradiation, visible light, or ultraviolet (UV) light. Single component curing systems consist of a resin that hardens through the application of heat or a reaction with surface moisture. Two-component and multi-component curing systems consist of two or more resins and a hardener, crosslinker, activator or catalyst. 

Specifications

Selecting electrical and electronic resins requires an analysis of physical, mechanical, thermal, electrical, and optical properties. Physical properties include viscosity, gap fill, melt flow index (MFI), and water absorption. Melt flow index (MFI) is the output flow occurring in a 10-minute period through a standard die while a fixed pressure is applied via a piston to a 190° C melt. Mechanical properties include tensile strength, tensile modulus, and elongation. Thermal properties include temperature range, deflection temperature, thermal conductivity, and the coefficient of thermal expansion (CTE). Resistivity, dielectric strength, and dielectric constant are important electrical properties. Optical properties include index of refraction, a measure of the speed of light in a material, and transmission.  

Electrical And Electronic Resins Applications

Electrical and electronic resins are used in many industries and applications. Some products are used in the manufacture of printed circuit boards (PCBs). Others are designed for electrical power and high voltage products such as generators, transformers, circuit breakers, and motor assemblies. Specialized electrical and electronic resins meet military specifications (MIL-SPEC) and are suitable for many aerospace applications. Products for automotive and optoelectronic applications are also available. Flame retardant materials resist ignition or reduce the spread of flames when exposed to high temperatures. Flexible or dampening materials form layers that can bend without cracking or delaminating.