Fillers - Another Component of FR - 4 Material

The role of fillers is to meet higher requirements for electrical or mechanical properties.

 For example:

Nelco's N4000 - 7 uses fillers to increase the glass transition temperature (Tg) and reduce the coefficient of thermal expansion (CTE).
Hitachi's MCF - 6000E adds fillers to enhance the filling performance.
Rogers' RO4350B incorporates ceramic particles as fillers to control the dielectric constant.

In addition, by adding other fillers as flame retardants to replace halogen flame retardants, the requirement for being halogen - free can be achieved.

Alright, the above are the basic components of our PCB copper - clad laminates. Now, let's take a look at the production process of copper - clad laminates: