PCB Base Material Performance Problems
To improve PCB performance, we need to increase the performance of PCB base material. This can be achieved by circuit densification and higher circuit operating frequency.
Higher Circuit Operating Frequencies
When the signal frequency is increased to the extent of GHz, skin depth phenomena occurs, and most of the signal travels through the outer part of the conductor. This results in signal attenuation due to signal loss because of the rough surface of foil.
To increase PCB performance, more circuits can be placed on per unit area of the printed circuit board. Printed circuit densification has achieved lots of developments in copper foil technology.
High temperature elongation is class 3 copper foil, showing good elongation and excellent ductility properties at high temperature.
Low Profile and Reverse Treated Copper Foils
The etching of low profile foil causes more control of the circuit track geometry. On the other hand, large tooth structures of standard profiles and thin laminates can lead to uneven dielectric thickness, resulting in difficulty in impedance control. Reverse treated foil has advantage to etch very fine circuit traces and improve the photo resist adhesion.
Thin Layer Copper Foils
Thin layer copper foil is used to etch the fine line circuit. 9.0 micron and 5.0 micron copper foils are used for high-density fine line circuits.