How to prevent PCB board bending and board warping from going through the reflow furnace?

Everyone knows how to prevent PCB bending and board warping from going through the reflow furnace. The following is an explanation for everyone:

1. Reduce the influence of temperature on PCB board stress

Dado que a “temperatura” é a principal fonte de estrés da placa, sempre que a temperatura do forno de refluxo se rebaixa ou a velocidade de quecemento e arrefriamento da tarxeta no forno de refluxo se reduza, a aparición de flexión e deformación da placa pode ser moito. reducido. Non obstante, poden producirse outros efectos secundarios, como un curtocircuíto de soldadura.

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2. Usando folla de alta Tg

Tg é a temperatura de transición vítrea, é dicir, a temperatura á que o material cambia do estado de vidro ao estado de caucho. Canto menor sexa o valor Tg do material, máis rápido comezará a suavizar o taboleiro despois de entrar no forno de refluxo e o tempo que tarda en converterse en estado de goma branda. Tamén se fará máis longo e, por suposto, a deformación da tarxeta será máis grave. . Usar unha placa de Tg máis alta pode aumentar a súa capacidade de soportar a tensión e a deformación, pero o prezo do material é relativamente alto.

3. Aumenta o grosor da placa de circuíto

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, and even a thickness of 0.6mm. It is really difficult for such a thickness to keep the board from deforming after the reflow furnace. 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 bending and deformation of the board.

4. Reduce the size of the circuit board and reduce the number of puzzles

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, dent and deformation 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, the depression and deformation caused by the weight of the circuit board can be reduced. The reduction in the number of panels is also based on this reason. Low dent deformation.

5. Accesorio de bandexa do forno usado

If the above methods are difficult to achieve, *reflow carrier/template is used to reduce the amount of deformation. The reason why the reflow carrier/template can reduce the bending of the plate is because it is hoped whether it is thermal expansion or cold contraction. 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 can also maintain the size of the garden.

Se o palé dunha soa capa non pode reducir a deformación da placa de circuíto, debe engadirse unha tapa para fixar a placa de circuíto cos palés superior e inferior. Isto pode reducir moito o problema da deformación da placa de circuíto a través do forno de refluxo. Non obstante, esta bandexa de forno é bastante cara, e ten que ser colocada e reciclada manualmente.

6. Use Router en lugar de V-Cut para usar a placa secundaria
Dado que V-Cut destruirá a resistencia estrutural do panel entre as placas de circuíto, intente non usar a subplaca V-Cut nin reducir a profundidade do V-Cut.