What are the reasons for cracking of electronic potting glue?

Epoxy resin potting compound has many advantages, such as excellent mechanical properties, electrical insulation, heat resistance,corrosion resistance, and good bonding properties with various materials, so it is widely used in the overall potting and sealing of electrical equipment such as dry-type transformers, mutual inductors, and reactors. However, with the development of the electrical field, the use environment of electrical appliances is becoming more and more harsh, and epoxy resin potting compounds have gradually exposed their defects, that is, the cured product is prone to cracking, especially in low temperature environments. The low-temperature cracking problem of epoxy resin potting compounds seriously affects the quality of electrical products and the safety and stability in use, and has always been an urgent problem to be solved in epoxy resin potting work. Therefore, it is very important to study how to improve the anti-cracking performance of epoxy resin potting compounds.

There are many reasons for low-temperature cracking of epoxy resin potting materials, such as formula design, product structure design and potting process. At the same time, the occurrence of low-temperature cracking is often the result of the combined effect of the above factors. Among them, epoxy resin potting materials will produce large internal stress during the curing process due to factors such as formula design, product structure design, and potting process. Under the action of internal stress, defects of varying degrees and fine cracks in the potting material expand and cause cracking. Therefore, the existence of internal stress is the root cause of potting material cracking.

Epoxy potting glue is typically a two-component system:component A consists of modified epoxy resin,pigments,fillers,and additives,with a temperature resistance limit of 120°C,while component B is an amine or acid anhydride curing agent,which can lead to bubble formation.Acid anhydrides offer better temperature resistance but poorer solvent and alkali resistance,and after curing,they form hard thermosets prone to cracking in fluctuating temperatures.Structurally,epoxy resins with high epoxy values are strong but brittle,while those with medium or low values offer better thermal performance but lower strength.