In the production of PCB circuit board backwelding furnace prone to plate bending and plate warping, so how to prevent PCB circuit board backwelding furnace plate bending and plate warping, Benlida PCB for you to explain the following:
1. Reduce the influence of temperature on the stress of PCB circuit board
Since "temperature" is the main source of circuit board stress, so as long as the temperature of the backwelding furnace or slow down the circuit board production in the backwelding furnace temperature and cooling speed, can greatly reduce the bending and warping of the plate. But there may be other side effects, such as a short circuit in the solder.
2. Benlida PCB adopts high Tg board
Tg is the glass conversion temperature, that is, the temperature at which the material changes from glass state to rubber state. The lower the Tg value is, the faster the circuit board becomes soft after entering the backwelding furnace, and the longer it takes to become soft rubber state, the more serious the deformation of the circuit board will be of course. The board with higher Tg can increase its ability to withstand stress and deformation, but the price of circuit board production is relatively high.
3. Increase the thickness of the PCB board
Many electronic products in order to achieve the purpose of thinner, the thickness of the circuit board has been left 1.0mm, 0.8mm, and even 0.6mm thickness, such a thickness to keep the circuit board after the welding furnace without deformation, really a bit of a force, it is suggested that if there is no light and thin requirements, the circuit board can use the thickness of 1.6mm, Can greatly reduce the risk of bending and deformation of the plate.
4. Reduce the size of the circuit board and reduce the number of boards
Since most of the backwelding furnaces use chains to drive the circuit board forward, the PCB with larger design size will sag and deform in the backwelding furnace because of its own weight, so try to put the long side of the circuit board as the board side on the chain of the backwelding furnace, you can reduce the weight of the circuit board caused by the sag deformation, reduce the number of plates is also based on this reason, That is to say, when the furnace, try to use the narrow side of the vertical direction of the furnace, can reach the lowest depression deformation.
5. The tray fixture has been used
If the above methods are difficult to achieve, the last thing is to use the furnace tray to reduce the deformation. The reason why the furnace tray can reduce the bending and warped plate is that no matter it is hot expansion or cold contraction, it is hoped that the tray can fix the circuit board until the temperature of the circuit board is lower than the Tg value and begins to harden again, and it can still maintain the size of the garden.
If a single layer of tray can not reduce the deformation of the circuit board, it is necessary to add a layer of cover, the circuit board with two layers of tray clip up, so that you can greatly reduce the circuit board over the welding furnace deformation problem. But the trays are expensive, and you have to add labor to place and retrieve them.
6. Use the Router instead of the V-Cut
Since V-cuts can damage the structural strength of the board, try not to use V-Cut subboards, or reduce the depth of the V-Cut.