Printed Circuit Boards (PCBs) are the building blocks of many electrical devices. It is a laminated sheet with insulating and conducting layers. In this board, the copper layer is etched to form printed electrical wiring, and insulators, resistors, and capacitors are soldered upon it.
Different types of PCBs include single-layered, double-layered, and multi-layered. Each of them has a separate function.
A variety of materials are used in the manufacturing of PCBs. The materials are of immense importance as they affect the performance of the board. They are carefully selected while focusing on the need for temperature resistance, conductivity, resistance, and flexibility. Each layer of the board is built using different materials. Here we will discuss each layer of the PCB and the materials used.
The substrate layer is the base of the Printed Circuit Board. It provides rigidity. It is a non-conductive layer. It is a plate made of glass fiber, coated with a resin epoxy layer. Many options are available to form this layer. Dielectric materials such as FR4 and PTFE (Teflon) are commonly employed for this purpose.
FR4:FR stands for flame resistance, and ‘4’ here indicates glass-reinforced epoxy laminate. FR4 does not only provide flame resistance, but it is water-resistant as well. It is the most common material used in PCB manufacturing. It provides strength to the board.
- PTFE (Teflon):
Teflon is used in boards that require flexibility. It resists high temperatures and is also flame resistant. Devices that require high frequency and speed use boards made up of Teflon. It is lightweight yet provides strength to the board.
Copper is the most commonly used metal in PCBs because it is a highly conductive metal. Other metals, such as aluminum and iron, may also be used instead of copper. Copper is first spread over the surface and then etched to form printed electrical wiring. It helps to create a circuit and provide conduction. The amount of copper applied depends upon the resistance, impedance, and amount of voltage to be transmitted. The board type determines the number of copper layers. The number of layers and the amount of copper utilized also affect the price of the PCB board. Surface Mount Technology (SMT), which uses solder paste, is applied over this layer to mount other components upon it.
Solder Mask Layer:
The solder mask layer is applied over the copper layer. It prevents copper from contacting any other metal. It helps in avoiding unnecessary connections between the solder joints on the board. It is a layer of polymer that also protects the copper from oxidation. It also gives color to the PCB. Other components of the board are fixed on this layer.
Silk Screen Layer:
The topmost layer of the PCB board is the silk screen layer. It helps to print specific information on the board. It helps mark the testing points and reference indicators for placing the components on the PCB. It also provides warning symbols such as indicating the voltage and current.
The material used for silk screening is a permanent, non-conductive epoxy ink. It comes in different colors, but white is the most commonly employed color.
The choice of material is a crucial decision. It affects the overall function of the board. The final result required should be the criteria for choosing the materials. Each material used has several pros and cons. It also determines the cost of the board.
Therefore, it is required to choose materials that may result in a high-quality product that is cost-effective and reliable. It should also be built according to the user’s needs and perform all the required functions.