Thermal solution for power adapter

Thermal solution for power adapter

Power adapter is a power supply conversion device for small portable electronic equipment and electronic appliances. The power adapter is generally composed of a shell, a power transformer and a rectifier circuit. According to its output type, it can be divided into AC output type and DC output type; according to the connection method, it can be divided into wall type and desktop type. Power adapters are widely used in industrial automation control, military equipment, scientific research equipment, LED lighting, industrial control equipment, communication equipment, power equipment, instrumentation and other fields.

Since a large number of high-power semiconductor devices are used in the power adapter, such as rectifier bridge stacks, high-current rectifier tubes, high-power triodes or field effect transistors and other devices, they will generate a lot of heat when they work. Once the power supply temperature exceeds 75 ℃ or more, If the heat cannot be discharged in time and kept at a reasonable level, the normal operation of the power adapter will be affected, and the power adapter will be damaged in severe cases. Usually, power adapter manufacturers will use some thermally conductive insulating materials to help the power supply to dissipate heat during design and production. What are the thermally conductive insulating materials commonly used in power adapter cooling solutions?

Thermally conductive potting compound

Thermal adhesive potting is divided into partial potting and overall potting. The interior of the power adapter is uneven and irregular. What is needed is a thermal conductive material that can completely wrap the transformer and cannot be moved at will. Partial potting is generally concentrated in the case where the heat generation is large and cannot be replaced by other thermally conductive materials. The overall potting is because some power supplies have to work outdoors for a long time. In addition to solving the problem of heat dissipation, the waterproof and sealing of the power supply should also be considered, so the outdoor power supply basically adopts the overall potting for heat dissipation.

 potting compound

Thermally conductive silicone sheet

For the power supply industry, the proportion of thermally conductive silicone sheets is usually small, but sometimes it is indispensable. Usually, the application of thermally conductive silicone sheets for power adapters is mainly concentrated on the PCB board. A special application and demand must be There will be a special supply to meet it. The thermal conductive silicone sheet is applied on the PCB board, which has many functions such as high thermal conductivity, electrical insulation, shock resistance and puncture resistance, and can effectively solve the safety problem for the client.

thermal pad
thermal pad

One-component thermally conductive gel

One-component gel is usually used for local heat conduction of power components, and at the same time can play the role of fixing components, and has good adhesion and sealing for both metal and non-metal.

thermal conductive gel
thermal conductive gel

Thermally conductive silicone film

Generally used in power MOS tube packaging, conventional standard parts TO-220, TO-3P, etc., usually apply a layer of silicone grease on the silicon film and MOS tube to increase the fit and reduce the thermal resistance.

Thermally conductive silicone film

Alumina ceramics

Whether it is thermal conductivity, temperature resistance range or insulation performance, it is far superior to thermal conductive silicone cloth. It can be used to replace the position of silicone rubber in MOS tubes. There are standard parts for TO-220 and TO-3P series, which need to be increased by applying silicone grease. Contact area with MOS tube.

Alumina ceramics

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