1. Surface quality requirements of heatsink

1.1 the surface of the heatsink shall be free from shrinkage, corrosion, crack and other defects;

1.2 metal fasteners (pressure plate, gland, disc spring) of flat-plate heatsink and conductive plates of water-cooled heatsink shall be protected by coating;

1.3 the maximum allowable value of surface roughness Ra of the cooling body table is 3.2m;

1.4 the flatness of the cooling body’s table shall not be lower than grade 9;

1.5 the surface of the heatsink (including heatsink, fasteners and insulating parts) used for power semiconductor devices with wet and hot belts shall be protected and its resistance to moisture, salt spray and cold shall meet the corresponding standards for tropical power semiconductor devices;

1.6 fasteners and insulators for heatsinks shall comply with GBB446.3 (heatsink insulators and fasteners for power semiconductor devices)

1.7 tightening torque or tightening pressure of the heatsink and power semiconductor installation shall comply with the relevant provision of the device product standard;

1.8 sizes of mounting center locating pin for plate cooling body table: 2.5mm in diameter, 1mm higher than the table

2. Requirements for the use of environmental conditions

2.1 water quality of cooling water shall be required to have a resistivity of circulating water not less than 2.5Ki2 and a PH value between 6}9; The inlet water temperature shall not be higher than 35℃, and the water flow shall be 4-8l /min;

2.2 when used in high-voltage or high-voltage devices, the water quality requirements or higher water quality requirements must be ensured;

2.3 when the water-cooled heatsink is working, special attention should be given to preventing water leakage, blocking and condensation.

2.4 when installing the air-cooled heatsink, the heatsink blade shall follow the cooling air flow direction; Inlet air temperature not higher than 400C, inlet wind speed of 4-6mls;

2.5 as the air-cooled heatsink has the characteristics of wind resistance parameters, when selecting the heatsink in the whole machine, the relationship curves of heat resistance, flow resistance and wind speed should be checked according to the load requirements and fan capacity, and the heat resistance and wind resistance of the heatsink should be taken into comprehensive consideration.

3. Hazard and identification of inferior heatsink

Appeared on the market a large number of price low quality inferior heatsink, this kind of heatsinkno matter from the aspect such as heat sink body material, processing requirement, component quality and so on the regulation that has bigger gap with national industry standard, have bigger influence to the life of the device and complete machine quality in using. Users can be identified from the following aspects:

3.1 quality of material (purity, thickness, processing accuracy, etc.) and manufacturing process (casting cracks, shrinkage holes, etc.), inferior material and rough defective process, will directly lead to the thermal conductivity of the heatsink;

3.2 surface roughness and surface degree of heatsink contact table directly affect thermal resistance and pressure drop;

3.3 heatsink disc springs, should ensure that after 24 hours after flattening, the free height should be stable, otherwise the use of a period of time after the spring may fail, will lead to poor contact between the heatsink and the core.

4. Problems to be noticed in the repeated use of heatsink replacement components

A lot of pressure or torque is required when installing a heatsink. Because the diameter of the cooling body table is larger than the diameter of the tube core, under the action of this pressure or torque, the cooling body table will inevitably deform. If will be the same diameter or larger diameter of the core, installed in the heatsink, will lead to the table and the core surface of the contact between the underprivileged, thus can not ensure good cooling effect.

If the user needs to reuse the heatsink, the surface roughness, parallelism and flatness of the cooling body surface must be secured to meet the requirements, or the device will be easily damaged due to overheating in operation. Especially water cools series heatsink, before reuse, must check its mesa deformation condition carefully, if have apparent sag phenomenon, answer to replace.

In order to ensure effective cooling conditions, each tube core should have a corresponding heatsink matching.

5. SS series heatsink condensation prevention

In hot and humid season, water cooling heatsink is prone to condensation phenomenon, if not pay attention, it is very easy to cause equipment insulation decline and cause short circuit fault. For most use environments, the following should be noted to prevent condensation.

5.1 in the hot and humid season, pay attention to the temperature difference between ambient temperature and cooling water not less than 5;

5.2 in case of power failure, water shall be stopped immediately after the knife is closed; When starting, the switch should be suspended immediately after the water is opened. The operation of opening and closing is closely related to the operation of cutting off the water. The order cannot be stopped.

6. High frequency application