How To: Printed Circuit Board Assemblies
Printed Circuit Board Assemblies, or PCB Assemblies, have been around since the 1920’s when rudimentary Printed Circuit Boards were created from layered Masonite, into which holes were drilled and flat wires were riveted to and connected through the Masonite board. These PCBs were used in early tube style radios and gramophones.
PCB Assemblies have come a long way since then. Today, Printed Circuit Boards are found in the advanced equipment used in the medical, aerospace, defense, electronics, computer, manufacturing and other technology-forward industries.
What is a Printed Circuit Board?
A Printed Circuit Board, or PCB, is a self-contained unit of interconnected electronic components that are fastened to an insulating board. A thin layer of conducting material is deposited onto the surface of the insulating board, onto which electronic components are placed and soldered to create the interconnecting circuits.
How are the Electrical Components Connected on a Circuit Board?
The electrical components on a PCB board can be connected through two different methods:
- Through Hole Technology: this technology involves pushing the leads through small holes in the insulating board and connecting them through soldering on the other side of the board. This method is now considered to be ‘older technology’ but is still commonly used today.
- Surface Mount Technology: J- or L-shaped extensions of each electrical component are held in place by a solder paste that is melted in an oven to create a firm connection between the circuits. While this technology involves more upfront investment and care in the creation of the circuit board, it is generally considered to be the more modern way of creating PCB Assemblies.
Types of Printed Circuit Boards
There are 3 primary types of Printed circuit Boards:
- Single-sided: as the name implies, these boards are designed with circuit traces that are on one side of the PCB only.Therefore the assembly only has components on one side of the insulating board. These are more common in PCB assemblies that perform simple functions.
- Double–sided: in this type of PCB, holes are drilled in the board to make electrical connections between circuits on opposite sides of the board by using plated thru holes Components can then be mounted on either side of the circuit board assembly.
- Multi–layered: this type involves layers of printed circuits with insulation between them, connected through holes in the boards. The inner layers are very thin and are laminated together in a heated press. These are typically used for very complex assemblies that carry out multiple functions, individual layers can be mixtures of signal/power/and ground planes.
PCB construction technologies and PCB applications continue to evolve and advance, as more advanced electronic circuits are needed for higher-density circuit applications.
In our next article, we’ll discuss the history of PCB Boards – followed by an article that describes some of the primary uses of PCB assemblies in various industries.