Bending and warping are easy to occur when PCB circuit board is produced through reflow oven. How to prevent bending and warping when PCB circuit board is produced through reflow oven is explained in detail below:

1. Reduce the influence of temperature on PCB stress

Since "temperature" is the main source of PCB stress, as long as the temperature of reflow oven is reduced or the heating and cooling rate of PCB production in reflow oven is slowed down, the occurrence of bending and warping can be greatly reduced. However, there may be other side effects, such as solder short circuit.

2. Benlida PCB adopts high Tg board

TG is the glass transition temperature, that is, the temperature at which the material changes from the glassy state to the rubberized state. The lower the TG value of the material, the faster the circuit board begins to soften after entering the reflow oven, and the longer the time to become soft rubberized state will be, so the more serious the deformation of the circuit board will be. Using higher Tg board can increase its ability to bear stress and deformation, but the price of circuit board is relatively high.

3. Increase the thickness of PCB

Many electronic products in order to achieve the purpose of thinner, the thickness of the circuit board has been left 1.0 mm, 0.8 mm, or even 0.6 mm thickness, such a thickness to keep the circuit board after reflow furnace does not deform, really a bit difficult, it is suggested that if there is no thin requirements, the circuit board can use 1.6 mm thickness, can greatly reduce the risk of bending and deformation.

4. Reduce the size of the circuit board and the number of panels

Since most reflow ovens use chains to drive the circuit board forward, the larger the PCB design size is, the larger the PCB will sag and deform in the reflow oven due to its own weight. Therefore, if the long side of the circuit board is put on the chain of the reflow oven as the board edge as far as possible, the sag and deformation caused by the weight of the circuit board itself can be reduced, and the number of panels can be reduced for this reason, That is to say, when the furnace, try to use the narrow side perpendicular to the direction of the furnace, can achieve to low sag deformation.

5. Used the pallet fixture

If the above methods are difficult to achieve, the last is to use the furnace tray to reduce the deformation. The reason why the furnace tray can reduce the bending and warping of the board is that no matter it is thermal expansion or cold contraction, the tray is expected to be able to fix the circuit board. When the temperature of the circuit board is lower than TG value and begins to harden again, it can still maintain the round size.

If the single-layer tray can not reduce the deformation of the circuit board, we must add a layer of cover to clamp the circuit board with two layers of trays, which can greatly reduce the deformation of the circuit board through the reflow oven. However, this furnace tray is very expensive, and also need to add manual to place and recycle the tray.

6. Use router instead of V-CUT

Since the V-CUT will damage the structural strength of the circuit boards, try not to use the V-CUT split or reduce the depth of the V-CUT.

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