4 layer PCB is laminated on the basis of double-sided PCB, PP and copper foil are added on both sides of the double-sided PCB. Usually, the layout of the4 layer PCB is signal wire-ground wire-power supply-signal.
4 layer PCB is made by lamination on the basis of the double-sided PCB. During the lamination, copper foil and PP are added to the two sides of the double-sided PCB, and then the 4 layer PCB is formed by high-temperature pressing. Some people would ask: what is the difference between double-sided PCB and four-layer PCB? The cropped double-sided PCB can be drilled directly on the machine without lamination, while the 4 layer PCB will enter the lamination process after some circuits are etched in the inner layer. Finally, drill holes can be made after lamination.
(1) Line width:
Usually, the signal line is set up 6mil, and the remaining power lines are 5V and 3.3V or it can be set up 10mil, 20mil respectively.
Normally, there are about 2-3 types of vias on a PCB. The designed conductor width and conductor spacing should take the production process capability of the PCB manufacturer into consideration. If the conductor width and conductor spacing we designed are over the production capacity of the partner, it may increase unnecessary production costs, and even need to change the supplier. Therefore, when designing the conductor width and conductor spacing, we should basically control it at 4/4mil and the via 12mil, then the manufacturers above 85% are able to put them into production. The conductor width and conductor spacing here refer to the size between elements such as line-to-hole, line-to-line, line-to-pad, line-to-via when setting rules.
The setting rules consider the design bottleneck in the design file. If there is a 1mm BGA chip, its pin depth is relatively shallow, and only one signal line is needed to be set between two rows of pins and it can be set to 6/6mil. If pin depth is relatively deep, two signal lines need to be taken between the two rows of pins and it can set to 4/4mil. If there is a 0.65mm BGA chip, it needs to be changed to HDI blind via design. Generally speaking, if it is larger than the design bottleneck, then the regional rules can be set. Local line width and moment are designed to be smaller and the other places on the board could be larger to facilitate production and improve the qualification rate.
(3) Copper foil:
Under normal circumstances, modifications can be made.
If you have questions about our 4-layer PCB production capacity, or the specifications required for your custom project are not listed on this page, please feel free to contact us. We will reply within one workday. We will continue to provide quotation support and design support. Welcome to learn about our production process.