PCB News - The influence of the residual copper rate in the inner layer of the circuit board on the expansion and contraction of the board

The influence of the residual copper rate in the inner layer of the circuit board on the expansion and contraction of the board

There are many factors that affect the expansion and contraction of PCB boards, including the symmetry of the graphic design, the characteristics of the core material, the dimensional stability of the film, the operation problems in the production process, environmental problems, and so on. The following PCB board factory takes the influence of the residual copper rate of the inner layer of the circuit board on the expansion and contraction of the board as an example to make a simple summary.

One. For the expansion and contraction of the core board after the circuit board is etched (common four-layer circuit board laminated structure)

1. The thickness is 0.1mm, and the Hoz core board with the surface copper thickness is larger than the core board with the surface copper thickness of 2oz.

2. When other conditions are the same, the surface copper Hoz core board has a large warp shrinkage, while the surface copper 2oz core board shrinks in the warp direction;

3. The residual copper rate of the circuit board has an obvious impact on the surface copper Hoz core board. The lower the residual copper rate, the greater the expansion and contraction, and the more significant meridional changes.

2. For the expansion and contraction of the core board after pressing (the pressing structure of the ordinary four-layer PCB board)

1. When other conditions are the same, the weft shrinkage of the surface copper thickness 2oz core board is more obvious than that of the surface copper thickness Hoz core board;

2. The warp-direction expansion and contraction of the same circuit board model core board is larger than the weft-direction expansion and contraction, and this phenomenon becomes more obvious as the copper thickness of the surface increases;

3. When other conditions are the same, the higher the residual copper rate in the inner layer of the circuit board, the better the dimensional stability of pressing, and the dimensional stability in the weft direction is better than that in the warp direction;

4. When other conditions are the same, the higher the residual copper rate in the inner layer of the circuit board, the smaller the compression expansion and shrinkage of the core board, which tends to be linear, and the warp direction change is more significant;

5. When the residual copper rate of the inner layer of the circuit board is less than 40%, the thickness of the core board with a thickness of 0.1mm and the thickness of 2oz is larger than that of the core board with a thickness of Hoz. When it is greater than 40%, the reverse is true.

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