In general, the Printed Circuit Board materials have two main purposes
Essentially, the materials present in the Printed Circuit Board (PCB) contain the transmission lines and components that enable the Radio Frequency (RF) and Microwave circuits. Various properties which should be considered are thermal, circuit’s electrical and mechanical characteristics.
In general, the types of PCB materials available are
Here, the majority of the substrate materials will mix with the epoxy.
The materials used to manufacture the Printed Circuit Boards are prepreg, copper foil, and copper-clad laminates.
Prepreg:Prepreg is a b-stage dielectric material that is tacky and allows the bonding of the copper foil and the different laminates.
Copper foil:Copper foil serves as the electrically conductive traces on the Printed Circuit Boards.
Copper-clad laminate:Piles of prepregs are bonded together to form the core of the Printed Circuit Boards. This core is generally cladded with copper foil on either side to form a copper-clad laminate.
These are lightweight materials that provide good resistance to corrosive substances. Since they don’t conduct electricity, it reduces the risk of short circuits in the Circuit Boards. They are also reduced in terms of cost when they are manufactured in high volumes.
These materials act as electrical conductors which is essential in order to maintain the circuits. They have a high tensile strength. The impact resistance is also high. These are the main PCB standoffs.
Rogers Corporation, as many of us have heard of, is a company that manufactures a line of PTFE-based laminates for high-frequency boards. As a design engineer, various factors will be provided in the datasheet like the dissipation factor (delta). The glass temperature value (Tg) is also present. For example, if we are looking for the values of the PTFE laminates’ datasheet, the value of ‘Tg’ for PTFE will be a little higher. Something that is most important to the manufacturers and something important is the notes provided in the datasheet below the table of values where the Dk values will also be there.
Materials can be chosen by considering
Below are the kind considerations.
The thermal conductivity deals with how fast the heat can be dissipated away from the hot area of a Circuit board to the cold area of the Circuit board. The typical thermal conductivity of an FR-4 board is in the mid-range. Let us consider we are developing the Printed Circuit Board for an industrial application say a lighting application, and thermal conductivity becomes crucial and important. And this is one of the reasons that the Printed Circuit Boards used for lighting applications are usually metal core boards. They’ll have an aluminium layer in their core. This aluminium layer is used in the core as it has very high thermal conductivity and it will pull away the heat from the Light Emitting Diodes (LEDs) and the power regulators from the Circuit Board. Therefore, the metal core provides high thermal conductivity.
This is also an important thermal property and commonly in the datasheet it is denoted as ‘Tg’. The value of Tg generally ranges from
