The increase in PCB circuit density brings many benefits. In terms of circuit performance, the improvement of circuit speed, the reduction of transmission distance, and the reduction of space occupied by individual devices reduce the time it takes for information to pass through the chip. This faster performance greatly benefits those who once waited for computers to complete a simple task. The increase in circuit density also reduces the power consumption of chips or circuits, and ENIAC, which requires small power plants to maintain operation, has been replaced by portable computers that rely on batteries and powerful functions

There are basically three ways to increase the density of printed circuits:

1. Reduce the conductor line width and the spacing between them.

2. Increase the number of circuit layers in the PCB.

3. Reduce the size and spacing of through holes and pads.

Reducing conductor linewidth requires very thin copper foil to achieve high yield in circuit etching processes. However, under the same other conditions, the lower profile results in a decrease in the adhesion of the foil to the dielectric.

It is important to balance the copper surface profile to adhere to the dielectric and have the ability to etch fine circuit features, let alone the impact of surface roughness on high-frequency electrical performance.

Consider copper foil manufacturers continuing to research methods to improve the chemical adhesion between the foil and the various dielectric materials used, while relying less on mechanical surfaces with strong adhesion and allowing for extremely low profile circuit etching and reducing conductor losses at high frequencies.

The increase in the number of layers of PCB circuit boards leads to an increase in overall multi-layer thickness and a thinning of individual dielectric layers, making thickness control and thermal reliability more important than ever before. Also add layers to the PCB that require improved registration functionality. A key variable for controlling registration is the dimensional stability of the laminate material, which becomes more challenging as the number of layers increases. Reducing the size of the path and gasket also requires improving the dimensional stability of the laminates to register high-level circuits, while smaller distances between paths require stronger thermal stability materials.