. Copy copper plates:

The copper -covered plate is double panel with structure symmetrical, no graphic, and the difference between copper foil and glass cloth CTE is almost the same, so there will be almost no deformation caused by different CTE during the pressing process.

However, the size of the copper covering machine is large, and the temperature difference between different areas of the hot disk will cause the resin to solidify and the degree of residation speed and degree in different regions during the pressure blending process. At the same time, the dynamic viscosity at different temperature increase rates is also large. Due to the local stress caused by the difference in solidification process.

Generally, this stress will maintain a balance after pressing, but it will gradually release deformation in future processing.

2. Pressing bumper:

The PCB factory pressing process is the main process of generating thermal stress. Similar to the compression of the copper cover plate, it will also produce local stress caused by the solidification process differences. Due to the thicker thickness, diverse graphics distribution, and more semi -solidary tablets, PCB boards will also produce reasons. Thermal stress will also be more difficult to eliminate than the copper plate.

The stress existing in the PCB board is released in the process of drilling, shape or barbecue, etc., resulting in deformation of the board.

3. Baking processes such as welding, characters, etc.:

Because the welded ink cannot be stacked with each other, the PCB board will be placed vertically in the shelf, the welding temperature is about 150 ° C, which just exceeds the TG point of the low and medium TG materials. It is easy to deform under the action of heavy or oven strong winds.

4. Hot wind weld flat:

Ordinary plate hot air welds are usually 225 ° C ~ 265 ° C, and the time is 3S-6S. The temperature of the hot air is 280 ° C ~ 300 ° C.

The entire welded plate is in the tin furnace from the room temperature, and the room temperature is washed within two minutes after the oven. The entire hot air welded process is the process of sudden heat.

Due to the different circuit board materials and uneven structure, thermal stress will inevitably occur during the hot and cold process, resulting in micro -strain and overall deformation warp.

5. Storage:

The PCB plate of the PCB factory is generally inserted in the shelf in the semi -finished phase. The shelf is not suitable for adjustment, or the stacking plates during storage will cause the board to produce mechanical deformation. In particular, the impact on plates below 2.0mm are more serious.

In addition to the above factors, there are still many factors affecting the deformation of PCB board