PCB Circuit Materials

The material of a PCB is important, and the choice depends on how the board will be used. Its glass transition temperature, or Tg, determines how the board will behave at different temperatures. Its dielectric constant and tracking resistance also play an important role. These values will change as the board is subjected to different stresses and voltage gradients, so a careful selection is required. The most common PCBs are made of fiberglass, but there are other options like aluminum circuit board.

A rigid pcb is a type of electronic circuit board that can’t be twisted or folded, making it less likely to deform and break. It has a copper base and can be single- or double-sided, depending on the needs of the device being created. Rigid PCBs are commonly found in GPS equipment, laptop computers, mobile phones, heart monitors, X-ray machines, and even control tower instrumentation.

To make a PCB, an insulator is laminated with a layer of copper. The copper is then etched and plated to form the conductive paths on the board. The holes in the copper are then plated with nickel to form the connections between the traces.

Different Types of PCB Circuit Materials

Several different materials are used as substrates in a PCB, including fiberglass (FR-4), epoxy, FR-1, CEM-1, G-11, and polyimide. They are chosen to meet specific criteria, such as their Tg, dielectric constant, and etchability. They are also rated for their thermal stability and chemical resistance.

There are two ways a pcb circuit can be etched: additive and subtractive. In additive methods, the bare laminate is covered with a photosensitive film which is imaged using light or chemicals. The exposed areas are then sensitized in a bath of palladium and similar metals to allow the bonding of copper ions. The copper is then deposited onto the board, followed by a protective solder mask and silk screen.

A silkscreen is a pattern printed on the surface of a PCB that contains reference designators, switch settings, test points, and other indications useful in assembling, testing, and using the circuit board. It is generally applied in a white color, but may be any other color that contrasts well with the PCB’s color. The PCB is then assembled, tested, and sometimes inspected.

A bare PCB is a plain piece of fiberglass or other non-conductive material. It is a starting point for more complex PCBs that must be able to hold and connect components in various configurations. It is also a good choice for PCBs that must be able to withstand bending or flexing, which is not possible with standard PCBs.