Why printed circuit boards are used

Once this technology was released for commercial use, electronic manufacturers quickly adopted it as it provided a much more cost effective solution than the traditional point to point construction of electronics. Over the years circuit board manufacturing has continued to grow in order to keep up with the increasing demands of newer, faster, and more complex electronic circuitry.

How a PCB is created for it to do what is required is a subject that could fill a library, but we will give you the basics of what it takes to design a printed circuit board here. A printed circuit board is a rigid structure that contains electrical circuitry made up of embedded metal wires called traces, and larger areas of metal called planes.

Electronic components are soldered to the top, bottom, or both layers of the board onto metal pads. These pads are connected to the board circuitry allowing the components to be interconnected together. The board may be composed of either a single layer of circuitry, circuitry on the top and bottom, or of multiple layers of circuitry stacked together. Circuit boards are built with a dielectric core material with poor electrical conducting properties to make the circuitry transmission as pure as possible, and then interspaced with additional layers of metal and dielectric as needed.

The standard dielectric material used for circuit boards is a flame resistant composite of woven fiberglass cloth and epoxy resin known as FR-4, while the metal traces and planes for the circuitry are usually composed of copper.

Printed circuit boards are used for a variety of purposes. You can find simple circuit boards in toys or controllers, while advanced circuit boards are used in computers and telecommunications. Some boards are made with flexible materials thereby allowing them to be used in unique cases and enclosures that require them to bend around other features of the device. Some boards are built with specialized materials due to the high frequencies that they operate at, while other boards have heavy layers of copper in them for high powered circuits used in industrial control panels and other similar applications.

There are boards designed for extreme environments such as underground sensors or the engine compartment of your car. Specialized circuit boards are used for aviation, space, and military applications that impose strict tolerances on their manufacturing and performance. Although there are many different applications for printed circuit boards, they are usually designed following a common process.

This is what we will examine next. An engineering team at work designing a printed circuit board. PCB design is broken into two main categories: schematic capture to create the circuitry connectivity in a diagram, and then PCB layout to design the actual physical circuit board.

The first step is to develop the library CAD parts that you will need for the design. This will include schematic symbols, simulation models, footprints for PCB layout, and step models for 3D printed circuit board display.

Once the libraries are ready the next step is to create the logical representation of the circuitry on a schematic. CAD tools are used to place the symbols on a schematic sheet, and then connect them together to form the circuitry. At the same time circuit simulation is run to verify that the design will work electrically the way it is intended to. Once these tasks are completed, the schematic tools will send their connectivity data over to the layout tools.

On the layout side of PCB design, the schematic connectivity is received and processed as nets that connect two or more component pins together. With an outline of the intended board shape on the screen, the layout designer will place the component footprints into their correct locations. Once these components are optimally organized, the next step is to connect the nets to the pins by drawing the traces and planes between the pins.

The CAD tools will have design rules built into them that prevent the traces of one net from touching another net, as well as governing many other widths and spaces needed for a complete design.

Once the routing is complete, the design tools are used again to create manufacturing drawings and the output files that the manufacturer will use to build the board. The design and manufacturing of a circuit board is a step by step process: schematic creation and simulation, setting up PCB design grids and DRCs, component placement, PCB routing, power planes, and finally assembling the BOM and building the board.

Next we will look more in depth at these steps. Although the design and manufacturing of a printed circuit board assembly can be generalized as schematic capture, PCB layout, and circuit board fabrication and assembly, the details of each step are very involved. Before you can start the design of the board within the CAD tools, you have to make sure that you have the library parts to work with first. Etches are made in the metal with acid to create pathways for electricity to travel among various components which are surface mounted on the board with solder.

The invention of printed circuit boards is one of the factors that has enabled electronic circuits to be smaller, more compact, and contained on a convenient, rugged board. Holes drilled into circuit boards allow components such as resistors and capacitors to be inserted and soldered through automation. Today, just about every electronic appliance in your home contains a printed circuit board of some type: computers, printers, televisions, stereos, musical instrument amplifiers and synthesizers, digital clocks, microwave ovens, telephone answering machines and even cell phones.

The "motherboard" in a computer is the main printed circuit board that is the heart of a computer. Other circuit boards inside a computer performs functions such as RAM random access memory , power supplies, modems and video "cards. Motorola's Quasar TVs were among the first to use removable printed circuit boards, designed for quick in-home repair.

Dan Keen is the publisher and editor of a county newspaper in New Jersey. Electronic components are mounted on pads that are electrically conductive often in copper or in plated through-holes. Between the pads and holes, copper lines are etched either between the fiberglass layers or on the front and back surfaces of the board.

This routing provides the required electrical connection between the components. The electronic components are attached to the board by soldering, i.