1. The effect of decreasing temperature on the stress of the board
Temperature is already the primary source of stress on the board. Simply lowering the temperature of the reflow oven or slowing down the rate of heating and cooling of the board in the reflow oven can greatly reduce the occurrence of board bending and warping. However, there may be other side effects that matter.
2. Using high Tg sheet materials
Tg is the glass transition temperature, which is the temperature at which the material changes from a glassy state to a rubbery state. The lower the Tg value, the faster the board begins to soften after entering the reflow furnace, and the longer the time it takes to become a soft rubbery state. Therefore, the deformation of the board will naturally become more severe. The use of higher Tg sheets can increase their ability to withstand stress and deformation, but the cost of the materials is relatively high.
3. Increase the thickness of the circuit board
In order to achieve a more frivolous intention, many electronic products now have a remaining thickness of 1.0mm, 0.8mm, and even 0.6mm for the board. It is a bit difficult to maintain this thickness when the board passes through the reflow oven without deformation. It is advocated that assuming there is no frivolous requirement, it is best to use a thickness of 1.6mm for the board, which can greatly reduce the risk of bending and deformation.

4. Reduce the standards of circuit boards and decrease the number of spliced boards
Most reflow furnaces already use chains to drive the circuit board forward. The larger the standard circuit board, the more it will deform due to its own weight. Therefore, try to place the long side of the circuit board as the board edge on the chain of the reflow furnace to reduce the deformation caused by the weight of the circuit board itself. The reason for reducing the number of spliced boards is also based on this, that is, when passing through the furnace, try to use the narrow side perpendicular to the furnace direction as much as possible to achieve the lowest amount of deformation.
5. Using furnace tray fixtures
Assuming that the above methods are difficult to achieve, the final solution is to use a reflow carrier/template to reduce deformation. The reason why the reflow carrier can lower the bending and warping of the board is because whether it is thermal expansion or contraction, it is expected that the tray can fix the circuit board ratio and the temperature of the circuit board is lower than the Tg value. After starting from scratch and hardening, it can still maintain the standard.
If a single-layer tray cannot reduce the deformation of the circuit board, an additional layer of cover must be added to clamp the circuit board between the upper and lower trays, which can greatly reduce the problem of circuit board deformation during reflow soldering. However, this furnace tray is quite expensive and requires manual labor to place and recycle the tray.
6. Replace the use of V-Cut with solid connections and stamp holes instead of using V-Cut for board splitting
If V-Cut can already damage the structural strength of the circuit board splicing, then try not to use V-Cut splitting or reduce the depth of V-Cut as much as possible.
Article source: Jiangmen single-sided and double-sided circuit boardhttp://www.yonghongpcb.com/