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AC / DC power module potting requirements


The potting and sealing of AC / DC power supply module is very important. This process not only involves the protection of AC / DC power supply module (waterproof, moisture-proof, dust-proof, anti-corrosion, etc.), but also involves the thermal design of AC-DC power supply module.

Power module potting materials are commonly divided into three categories: epoxy resin, polyurethane and silicone rubber

Epoxy resin can not be used for potting of stress sensitive and SMD modules due to its hardness, and is basically eliminated in the module power supply. However, due to its low cost, this epoxy resin is also used in the micro power supply which requires high cost. Some bad power supply manufacturers in China also use this epoxy resin for AC-DC power supply modules. However, due to the stress problem, the failure rate of this power supply is very high, and the purchasers of power supply modules are suffering.

At present, the most commonly used in the potting of the power module is the addition molding silica gel. This silica gel is generally 1:1, which is convenient for operation. When the AC-DC power module is designed to be potted, attention should be paid to its thermal conductivity. However, the adhesive capacity is not strong, and it can be improved by using primer.

Polyurethane has been used in China for a period of time. However, due to its high hardness, inconvenient maintenance of power modules, and the price reduction of silicone rubber, the performance price ratio of polyurethane is not high. Its application is basically absent in China.

Special attention should be paid to the thermal conductivity related to thermal design. We generally define the thermal conductivity of 0.5w/m · K as high thermal conductivity, and the thermal conductivity greater than 1 as extremely high thermal conductivity