How to prevent PCB board bending and board warping in the reflow furnace

Everyone knows how to prevent PCB bending and board warping from passing through the reflow furnace. The following is an explanation for everyone: 1. Reduce the temperature on the PCB board. Since 'temperature' is the main source of board stress, as long as the temperature of the reflow furnace is lowered or the rate of heating and cooling of the board in the reflow furnace is slowed, the occurrence of plate bending and warpage can be greatly reduced. . However, other side effects may occur, such as solder short circuit. 2. The Tg of the high Tg sheet is the glass transition temperature, that is, the temperature at which the material changes from the glass state to the rubber state. The lower the Tg value of the material, the faster the board starts to soften after entering the reflow furnace, and The time to become soft and rubbery will also be longer, and the deformation of the board will of course be more serious. Using a higher Tg plate can increase its ability to withstand stress and deformation, but the price of the material is relatively high. 3. Increase the thickness of the circuit board. In order to achieve the purpose of lighter and thinner for many electronic products, the thickness of the board has left 1.0mm, 0.8mm, or even a thickness of 0.6mm. This thickness should keep the board from going through the reflow furnace. Deformation is really difficult. It is recommended that if there is no requirement for lightness and thinness, the board* can use a thickness of 1.6mm, which can greatly reduce the risk of board bending and deformation. 4. Reduce the size of the circuit board and reduce the number of panels. Since most of the reflow furnaces use chains to drive the circuit board forward, the larger the size of the circuit board will be due to its own weight, and it will be deformed in the reflow furnace. So try to put the long side of the circuit board as the edge of the board on the chain of the reflow furnace, which can reduce the dent deformation caused by the weight of the circuit board itself. The reduction in the number of panels is also based on this reason, that is, when the furnace is passed. , Try to use the narrow side as far as possible to pass the furnace direction, which can achieve the lowest amount of depression deformation. 5. If the above-mentioned methods are difficult to use the furnace tray fixture, * is to use the furnace tray (reflow carrier/template) to reduce the amount of deformation, the reason why the furnace tray can reduce the bending of the plate is because no matter it is Thermal expansion or cold contraction, it is hoped that the tray can hold the circuit board and wait until the temperature of the circuit board is lower than the Tg value and start to harden again, and it can still maintain the size of the garden. If the single-layer pallet cannot reduce the deformation of the circuit board, a cover must be added to clamp the circuit board with the upper and lower pallets, which can greatly reduce the problem of the deformation of the circuit board through the reflow furnace. However, this oven tray is quite expensive, and it has to be manually placed and recycled. 6. Switch to using Router instead of V-Cut sub-boards. Since V-Cut will destroy the structural strength of the board between the circuit boards, try not to use V-Cut sub-boards or reduce the depth of V-Cut. Here to enter the pricing page https://www./