The area of the copper surface on the circuit board is uneven, which will worsen the bending and warping of the board.
1. Generally, a large-area copper foil is designed on the circuit board for grounding, and sometimes the Vcc layer is also designed with a large-area copper foil. When these large-area copper foils cannot be evenly distributed on the same piece When it is on the circuit board, it will cause the problem of uneven heat absorption and heat dissipation speed. Of course, the circuit board will also expand with heat and contract with cold. If the upper limit of the Tg value has been reached, the board will begin to soften, causing permanent deformation.
2. The connection points (vias, vias) of each layer on the circuit board will limit the expansion and contraction of the board.
Today's circuit boards are mostly multi-layer circuit boards, and there are connection points (vias) like rivets between layers. The connection points are divided into through holes, blind holes and buried holes. The expansion and contraction of the multi-layer circuit board will also indirectly cause the board to bend and warp.
