Circuit board designers may design odd numbered printed circuit boards. Why do you want to use it? Do not reduce the layer will make the circuit board is more thin? If the circuit board is less, if the wiring does not require additional layer. Isn't it cheaper? But in some cases, an increase in the cost of lower costs.
Odd PCB board raw material cost is slightly lower than even layer circuit board but odd layer PCB processing cost was significantly higher than that of the even number layer inner layer of PCB processing cost the same; but foil cladding / core structure significantly increased the processing cost of the outer. Because there is a layer of medium and deposited foil.
The plant production efficiency will be decreased by adding the foil to the core structure. Prior to laminating bonding, the odd number layer PCB needs to increase the non standard layer bonding process on the basis of the nuclear structure process. Compared with the nuclear structure. Outside the nucleus requires additional processing, which increases the risk of the outer layer being scratched and etched.
Balanced structure to avoid bending, nuclear structure and the application of the structure of the foil when the tension is different from the tension of the circuit board bending. With the increase of the thickness of the circuit board, the best reason for the design of the circuit board without odd layer is that the odd circuit board is easy to bend. When the PCB multilayer circuit bonding process is cooled. OEM PCBA foundry material with two different structure of the composite circuit board bending the greater the risk. The key to eliminating the bending of the circuit board is to use a balanced stack. Although a certain degree of bending of the PCB to meet the requirements of the specification, but the subsequent processing efficiency will be reduced, resulting in increased cost. Because the assembly requires special equipment and processes, component placement accuracy is reduced, it will damage the quality of.
Use even layer PCB
The following methods can be used to achieve the balance of stacking, reducing the cost of circuit board production, to avoid PCB bending. The following methods are arranged according to the preferred order. When an odd number of PCB is designed in the design.
1 a layer of signal layer and the use of. This method can be used if the power supply layer of the PCB is designed to be an even number and the signal layer is odd. The increase of the layer does not increase the cost, but it can shorten the delivery time, improve the quality of PCB.
2 add an additional power layer. This method can be used if the power supply layer of the circuit board is odd and the signal layer is even. One easy way is to add a layer of ground in the middle of the stack without changing the other settings. First, according to the odd layer PCB kind of wiring, and then in the middle of the formation, marking the remaining layer. This is the same as the electrical properties of the thick layer of the coating.
3 to add a blank signal layer to the center of the circuit board. This method minimizes cascade imbalance and improves the quality of PCB. First, according to the odd number layer wiring, and then add a layer of blank signal layer, mark the rest of the layer. In microwave circuits and mixed media (media with different dielectric constant) circuit.