Electronic devices surround us everywhere. Various devices exist, some of which are subtle, and others which attract a lot of attention. Whatever the device is, whether it is a wearable device that silently records your health, or a smartphone that continually interrupts your life, it will have some type of printed circuit board at its core.
It consists of traces of metal wires embedded in a rigid structure, and larger areas of metal, called planes, that form the electrical circuit. On top, bottom, or both layers of a board, electronic components are soldered to metal pads. Using these pads, the components can be interconnected to the board circuitry. Depending on how the board is constructed, it may consist of one layer of circuitry, two layers, or multiple layers.
As electronics continue to become faster, more complex, and more sophisticated, circuit board manufacturing has continued to grow. This section will provide you with an overview of what it takes to design a printed circuit board. The details of how a PCB is created in a Printed circuit board company would fill a book, but we will cover the basics here.
Printed circuit boards: what are they?
It consists of traces of metal wires embedded in a rigid structure, and larger areas of metal, called planes, that form the electrical circuit. On top, bottom, or both layers of a board, electronic components are soldered to metal pads. Using these pads, the components can be interconnected to the board circuitry. Depending on how the board is constructed, it may consist of one layer of circuitry, two layers, or multiple layers.
In order to make the circuitry transmission as pure as possible, circuit boards contain a dielectric core with poor electrical conductivity. Additional layers of metal and dielectric are then placed between the core and the metal. Dielectric materials for circuit boards are typically composed of FR-4, a flame-retardant composite of woven fiberglass cloth and epoxy resin, while the metal traces and planes for the circuitry are typically copper.
There are many applications for printed circuit boards. Toys and controllers, for example, use simple circuit boards, while computers and telecommunications use sophisticated circuit boards.
Flexible boards are commonly used in cases and enclosures that require them to bend around additional features of the device, since they can be placed in unique cases and enclosures. There are some boards built with special materials because of the high frequencies at which they operate while others have a thick layer of copper in them for use in high powered circuits such as those found on industrial control panels.
In extreme environments such as underground sensors or in your car’s engine compartment, there are boards that are tailored to these needs. In the aerospace, space, and military industries, specialized circuit boards need to meet strict manufacturing and performance standards.
Although printed circuit boards are used for a variety of applications, they are generally designed in a similar way. Let’s look at this in more detail.
Designing Printed Circuit Boards
Circuit boards must first be designed using PCB design tools, before they can be built. In PCB design, there are two categories: schematic capture and PCB layout. Schematic capture shows the circuit connections in a diagram; PCB layout shows how the board will be constructed.
In order to design the parts for the design, you must create a library CAD parts. A schematic symbol, a simulation model, a footprint for PCB layout, and a step model for a 3D display of printed circuit boards are included in this. Following the creation of the libraries, a schematic is then created to represent the circuitry logically. Schematics are drawn using CAD tools, and then the symbols are connected together to form a circuit.
At the same time, circuit simulations are run to ensure that the design will work as intended electrically. Schematic tools will transmit their connectivity data to layout tools once these tasks have been completed.
The schematic connectivity is received and processed on the layout side of the PCB design process as nets that connect two or more component pins. The layout designer will place the component footprints into the proper locations with an outline of the intended board shape on the screen. In order to connect the pins to the nets, the traces and planes between them must be drawn after the components are optimally organized. In addition to preventing trace lines from touching each other, CAD tools will also handle widths and spaces that are required to create a complete design. When the routing of the board is complete, the manufacturing drawings and output files are created with the design tools so that the manufacturing company can build the board.
In order to create a circuit board, several steps are needed: schematic generation and simulation, configuration of the PCB design grids and DRCs, component placement, routing the PCB, building the power planes, and finally putting the BOM together and building the circuit. Next, we will examine these steps in greater detail.
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