PCB Trace Technologies Inc makes high quality PCBs or printed circuit boards for the electronics industry. In common parlance, the industry also calls these circuit boards. To make the circuit boards function the way they are intended to, the boards require mounting components on them. These components can be passive and/or active. Component manufacturers typically make them from semiconductor materials.
The basic difference between circuit boards and semiconductors is the circuit board functions as the carrier for the semiconductor components mounted on the circuit board. While the components guide and control electrical signals that the assembly needs to function, the board offers a mechanical support for the components, and an electrical interconnection for the components.
Printed Circuit Boards
Printed Circuit Boards are typically flat boards that may be rigid or flexible. Usually, they have one or both sides with copper traces. PCBs can mount two types of components—through hole components and/or surface mount components. Some complicated boards may also have multiple layers. The composition of a PCB may have several elements:
Patterns and Traces
Patterns and traces made of copper are visible on one or both sides of the PCB. If the PCB is multilayered, patterns and traces will be present in the inner layers as well, but they may not be visible. Copper traces act as interconnections between various components that the PCB supports. Copper patterns may act as ground or shield layers for circuit operation.
An imaging and etching process creates the patterns and traces individually on each layer. Stacking and bonding the various layers forms the final structure of the board.
Substrate
Substrates are the dielectric base for the layers, on which the manufacturer establishes the patterns and traces. Apart from maintaining a suitable level of insulation between the copper patterns and traces on each layer, the manufacturer chooses the type of dielectric depending on the application of the PCB. For instance, FR4 is a common materials manufacturers choose for making general purpose PCBs. For high-speed or high-frequency PCBs, they opt for Polyimide or similar dielectric materials.
Vias and Through Holes
Vias and through holes are structures that the manufacturer makes in the PCB to facilitate interconnections between the copper patterns and traces of various layers. While a through hole may require drilling through all the layers of a PCB, vias may be buried and/or blind. Making a via requires drilling one or more layers with a mechanical drill bit or a laser beam.
Both vias and through holes need a copper barrel to make them conducting. The manufacturers achieve this by electroplating. Depending on the application, they may leave the vias and through holes without any filling, or fill them with conductive or non-conductive material.
Solder Resist
Atmospheric conditions can easily oxidize and discolor the exposed copper patterns and traces on the top most surface of a PCB. Manufacturers prevent this by coating the top surface with a layer of solder resist material, leaving out the pads on the patterns and traces that will hold a component. The solder resist also acts as an insulating layer.
Surface Finish
To prevent discoloring and oxidization of the exposed pads after the application of solder resist, manufacturers provide the pads with a surface finish. Manufacturers use materials like solder, gold, nickel, silver, and others as surface finish, depending on the application.
Legend Marking
As each PCB requires mounting components on them, manufacturers provide indication of the position of each component by marking its outline on the board. They also call this a silkscreen process by which they mark not only the outline, but also the identification of the component on the board.
Semiconductor Components
Active electronic components comprise many types of semiconductor materials. The choice of the semiconductor material depends primarily on the function and applicability of the component. Broadly, there are three types of components in common use:
Diodes
Basic diodes are components with two pins, a cathode and an anode. Most diodes allow current to flow internally from the anode to the cathode, while not allowing any reverse current flow. Depending on their function, there are various types of diodes:
- Power Diodes
- Signal Diodes
- Zener Diodes
- Avalanche Diodes
- Pin Diodes
- Tunnel Diodes, etc.
Transistors
Transistors are components with more than two pins. Their functionality and usefulness extend from switching signals to amplifying and controlling them. Depending on their construction, their classification is broadly:
- Power Transistors
- Signal Transistors
- Bipolar Transistors
- Field Effect Transistors
- Junction Field Effect Transistors
- Metal Oxide Semiconductor Field Effect Transistors
- Silicon Carbide Transistor, etc.
Integrated Circuits
By combining many diodes and transistors in suitable circuits in a single package, component manufacturers offer integrated circuits that can perform a plethora of tasks. There are various types of integrated circuits, large and small, that the electronic industry depends on. Most common among these are:
- Logic Integrated Circuits
- Optical Integrated Circuits
- Switching Integrated Circuits
- Analog Integrated Circuits
- Digital Integrated Circuits
- Power Integrated Circuits
- Very Large-Scale Integrated Circuits, etc.
Conclusion
Both, the circuit board and the semiconductors, are necessary for making a functional electronic assembly. Other components, namely, passives and electromechanical components are also necessary for making the semiconductors function to their specifications. The circuit board functions as the foundation for the components to remain anchored in one place. In addition, the circuit board also provides the basic interconnections between the components.
