source:Other information release time:2023-03-14 Hits: Popular:PCB Assembly company
1. The effect of lowering temperature on PCB board stress
Since "temperature" is the main source of the plate stress, as long as the temperature of the return furnace is reduced or the plate is slowed down in the welding furnace, the speed of the plate bending and plate warp can be greatly reduced. However, there may be other side effects, such as short -circuit welds.
2. Use high TG board
TG is the temperature of the glass conversion temperature, that is, the material that the material is transformed from glass state to rubber state. The lower the TG value, the faster it starts to become soft after entering the welding furnace. It will also become longer, and the deformation of the board will of course, the more serious. The use of higher TG boards can increase its ability to withstand stress deformation, but the price of relatively high material materials is also relatively high.
3. Increase the thickness of the circuit board
In order to achieve a lighter purpose, the thickness of the board is 1.0mm and 0.8mm, and even the thickness of 0.6mm has been left. This thickness must be kept in the welding furnace without deformation. It is really difficult to be strong. It is recommended that if there is no light requirement, board*can use the thickness of 1.6mm, which can greatly reduce the risk of plate bending and deformation.
4. Reduce the size of the circuit board and reduce the number of panels
Since most of the welding furnaces use chains to drive the circuit board to move forward, the larger the size of the circuit board will deform in the return furnace due to its own weight, so try to put the long side of the circuit board as the edge of the board on the edge of the board. On the chain of the welding furnace, the depression deformation caused by the weight of the circuit board itself can be reduced. The reduction of the number of panels is also based on this reason. That is to say Low depression deformation.
5. Use the furnace pallet to treat
If the above methods are difficult to make,*is to use the Reflow Carrier/Template to reduce the deformation. The reasons why the furnace tray can reduce the curve is because whether it is thermal expansion or cold shrinkage, I hope that they hope The tray can fix the circuit board and wait until the temperature of the circuit board is lower than that of the TG value and start to harden, and it can also maintain the size of the garden.
If a single -layer tray cannot reduce the deformation of the circuit board, you must add another layer of lid to clamp the circuit board with two layers of tray up and down, so as to greatly reduce the problem of the circuit board and the deformation of the welding furnace. However, this tray is very expensive, and it has to be manually put in and recycled the tray.
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