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Heat sink manufacturing supplier
National hotline:+86 13827205356
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Aluminum Heat Sink & Profile Manufacturing

address:No. 51 Luming Road Heavy River Management District - Qing Town Dongguan City

Q Q:2131405854

Telephone:+86 13827205356

mailbox:cnc@cncstamping.com

Power calculation for design heat sink

Small electronic heat sinks (transistor, motor, peltier, resistor, thermal resistance, pin fin) are made of aluminum alloy sheet through stamping process and surface treatment. The large heat sinks (engine, led, cpu cooler) are formed by extruding aluminum alloy into profiles, which are then made by machining and surface treatment. They have various shapes and sizes for different device installations and devices with different power consumption.

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Thermal resistance of heat sink
Small electronic heat sinks (transistor, motor, peltier, resistor, thermal resistance, pin fin) are made of aluminum alloy sheet through stamping process and surface treatment. The large heat sinks (engine, led, cpu cooler) are formed by extruding aluminum alloy into profiles, which are then made by machining and surface treatment. They have various shapes and sizes for different device installations and devices with different power consumption. Heat sinks are generally standard parts, but profiles can also be provided, which can be cut into a certain length by users to make non-standard heat sinks. The surface treatment of the heat sink includes electrophoretic paint or black oxygen polarization treatment, the purpose of which is to improve heat dissipation efficiency and insulation performance. It can increase by 10-15% under natural cooling and 3% under ventilation cooling. Electrophoresis painting can withstand voltage of 500~800V.
The heat sink manufacturers give thermal resistance values or related curves for different types of heat sinks, and provide different thermal resistance values under different heat dissipation co

Small heat sink    Large heat sink

Power calculation of heat sink
Any device has a certain loss during operation, and most of the loss becomes heat. Low-power devices have low loss and no heat sink is required. The power consumption of high-power devices is large. If no heat dissipation measures are taken, the temperature of the die can reach or exceed the allowable junction temperature, and the device will be damaged. Therefore, a heat sink must be added. The most commonly used is to install power devices on a heat sink, and use the heat sink to dissipate heat to the surrounding space. If necessary, add a cooling fan to enhance the cooling effect with a certain wind speed.
The flowing cold water cooling plate is used on the power devices of large equipment, which has a better heat dissipation effect. Heat dissipation calculation is to determine the appropriate heat dissipation measures and heat sinks through calculations under certain working conditions.
The power device is mounted on the heat sink. Its main heat flow direction is from the chip to the bottom of the heat sink, and the heat is dissipated to the surrounding space through the heat sink. If there is no fan to cool at a certain wind speed, this is called natural cooling or natural convection heat dissipation.

Black anodized heat sink
The heat transfer process has a certain thermal resistance. The thermal resistance from the device die to the bottom of the device is R JC, and the thermal resistance between the bottom of the device and the heat sink is R CS. The thermal resistance of the radiator to dissipate heat to the surrounding space is R SA, and the total thermal resistance R JA = R JC + R CS + R SA. If the maximum power loss of the device is PD, and the allowable junction temperature of the device is TJ and the ambient temperature is TA, the allowable total thermal resistance R JA can be obtained by the following formula.
R JA≤(TJ-TA)/PD
Then calculate the maximum allowable thermal resistance R SA from the radiator to the ambient temperature as:
R SA≤({T_{J}-T_{A}}\over{P_{D}})-(R JC+R CS)

Out of consideration of leaving room for design, TJ is generally set to 125°C. The environment temperature should also consider the worse case, generally set TA=40℃~60℃. The size of R JC is related to the size and package structure of the die, which can generally be found in the device data. The size of R CS is related to mounting technology and device packaging. If the device is installed with a heat sink after using thermal grease or thermal pad, the typical value of R CS is 0.1 0.2℃/W; If the bottom surface of the device is not insulated and an additional mica sheet is required for insulation, its R CS can reach 1°C/W. PD is the actual maximum power loss, which can be calculated according to the working conditions of different devices. In this way, R SA can be calculated, and a suitable radiator can be selected according to the calculated R SA value.