Six ways to prevent PCB warping


1, increase the thickness of the PCB board

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

2, reduce the size of the printed circuit board and reduce the number of patchwork boards

     Most of the soldering furnace are used to drive the chain circuit board forward, the larger the size of the circuit board will be because of its own weight, in the soldering furnace in the depression deformation, so try to put the long side of the circuit board as a board edge on the chain of the soldering furnace, you can reduce the weight of the circuit board itself caused by the deformation of the depression, the number of boards to reduce the board is based on the reason, which means that over the furnace, try to use a narrow side of the vertical over the furnace That is to say, when passing through the furnace, try to use the narrow side perpendicular to the direction of the furnace, so as to achieve the lowest amount of depression deformation.

3, change the use of Router instead of V-Cut sub-panel use

     V-Cut will destroy the structural strength of the circuit board between the patchwork, then try not to use V-Cut sub-panel, or reduce the depth of V-Cut.

4, reduce the temperature on the PCB board stress effects

   "Temperature" is the main source of board stress, so as long as the temperature of the soldering furnace to reduce or slow down the board in the soldering furnace to warm up and cool down the speed, you can greatly reduce the board bending and board warping occurs. However, there may be other side effects, such as solder shorts.

5, using high Tg plate

    Tg is the glass transition temperature, that is, the material from the glass state into the rubber state temperature, Tg value of the lower the material, said the plate into the soldering furnace began to soften the speed of the faster, and into a soft rubber state time will become longer, of course, the plate deformation will be more serious. The use of a higher Tg plate increases its ability to withstand stress and deformation, but the price of the material is relatively high. Narrower edges in the perpendicular to the oven direction will result in the lowest amount of dent deformation.

6, the use of the furnace tray fixtures

    If the above methods are difficult to do, the last is to use the furnace tray (reflow carrier/template) to reduce the amount of deformation, the furnace tray can reduce the board bending board warping is because no matter whether it is thermal expansion or contraction of cold, hope that the tray can be fixed circuit boards and wait until the temperature of the circuit board is lower than the value of the Tg began to re-hardening, but also to maintain the original size. If a single layer of the tray can not reduce the amount of deformation of the circuit board, it is necessary to add a layer of cover, the circuit board with the top and bottom of the two layers of the tray clamped together, so that you can greatly reduce the circuit board over the deformation of the soldering furnace. However, this over the furnace tray is quite expensive, and also have to add labor to place and recover the tray.

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