What is a Printed Circuit Board? Make Circuits by Connecting Components

Zachariah Peterson
|  Created: October 5, 2020

A printed circuit board (PCB) is an electrical circuit whose components and conductors are contained within a mechanical structure.

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A printed circuit assembly

A printed circuit board integrates components and conductors

A printed circuit board is an electrical circuit whose components and conductors are contained within a mechanical structure. Conductive features include copper traces, pads, heat sinks, or conductive planes. The mechanical structure is made with insulating material laminated between layers of conductive material. The overall structure is plated and covered with nonconductive solder mask and silk screen to legend electronic component location.

The printed circuit board is built by alternating layers of conductive copper with layers of nonconductive insulation material. During manufacture the inner copper layers are etched leaving intended traces of copper to connect circuit components. Once etched insulation material is laminated to the copper layers and so on until the printed circuit board is complete.

Electronic components are added to the outer layers of the printed circuit board when all the layers have been etched and laminated together. Surface mount parts are automatically applied with robots and through-hole parts are manually placed. All the pieces are then soldered onto the board using techniques such as reflow or wave soldering. The final assembly is plated after which solder mask and silk screen legending is applied.

History of Printed Circuit Boards in Today’s Landscape

Before we can get into answering what is a printed circuit board, it is best to understand where PCBs have come from. It’s been a tremendous journey moving toward HDI designs with hundreds of holes and PCBs whose electrical connections are powering everything from smartphones to heart rate monitors to rockets. The process from wiring board to flexible PCBs and wherever else technology takes us in the future has been fun.

Before printed circuit boards, electrical circuits were built by attaching individual wires to components. Conductive paths were accomplished by soldering metal components together with wire. Larger circuits with many electronic components contained many wires. The number of wires were so great that they could get tangled or inhabit a large space within a design. Debugging was difficult and reliability suffered. Manufacturing was slow necessitating manual soldering of multiple components to their wired connections.

Set net rules from the Properties Panel

Net rules for layout are established while drawing the schematic

Connect Electronic Components With Nets on Printed Circuit Boards

Remove the need for wires by routing nets with copper on multiayer boards. Working from the schematic place components and connect pins along the circuit board layers with thoughtful net placement. Start with auto-route and use manual routing for important nets. Altium Designer offers autoroute to help with multiple net routing.

Once you’ve considered net count within your schematic and determined routing needs for your layout consider design rules and constraints.

Printed Circuit Boards Use Schematics to Place and Route Components

Today printed circuit board software provides schematic capture to define circuits and their components for design into printed circuit boards. PCB designers work from the schematic to organize components onto a virtual board whose outline dimensions have been specified by the mechanical engineer on the design team. Components are placed and routing occurs following design rules to mitigate noise through carefully planned grounding planes and impedance planning.

Electronic products these days have numerous demands from flexible PCBs to surface-mount technology and components for tricky Printed Circuit assembly. A Printed Circuit Board manufacturing process will be improved significantly with software that can accurately keep track of holes, traces and materials in an organized and secure fashion. Further, drafting electronic devices will be made easier with schematic capture that can easily translate data files throughout the design process.

Use Properties Panel to set routing rules

Routing differential pairs parameters are set in Properties Panel

Use Unified EDA Software Environment to Map Circuits to Layouts

PCB designers consult with circuit designers to determine best practice for component placement, multilayer stack, net specifications, and base material selection. Procurement and supply chain enter the picture for material sourcing. Component libraries within the tool incorporate sourcing and pricing information along with electrical parameters. Fabrication vendors are engaged so material definitions for the layer stack coincide with practical Printed Circuit Board manufacturing processes.

Knowing your footprints and dimensioning limitations use Altium’s unified environment to incorporate into the layout.

Design Printed Circuit Boards in Altium’s Unified Environment

PCBs will only get more technologically intensive as the years press forward. Thankfully, design software is continually improving to make designing them easier. The least of your worries when designing your PCB should be in how to accurately convey to manufacturers the holes on your board, where to lay the copper foil, or how to apply the solder paste. The more layers your board has, the more you need the gold standard in CAD software for your copper standards.

Altium Designer has all the tools you need within a unified platform to design and build your printed circuit board. From schematic capture through release to production, mechanical dimensioning and outline drawing to board layout and component footprints, Altium has you covered. Rules may be set during schematic layout to define high-speed traces for impedance control. Components may be selected from a shared library so physical as well as electrical considerations can be incorporated into selection for downstream success.

Differential pairs are defined in schematic capture tool

Define differential pairs in schematic capture with instructional directives

Altium Realizes Circuit Design With Unified Printed Circuit Board Tools

You no longer need to worry that the circuit details you captured in your schematic will port to the layout. A PCB and all its associated substrate, copper, holes, layers, and traces will be a process to manufacture. But it doesn’t need to be a worrisome process when you have accurate and easy-to-read software outputs.

Altium’s unified environment incorporates the PCB layout tool so designers can follow the nets you laid down in the schematic. Use Directives within Schematic capture to communicate design constraints to your layout designer. Board outlines designed with your mechanical team easily import into Altium’s PCB layout tool. Component libraries are linked and consistent across the unified design environment. Impedance calculators follow specifications defined in the schematic.

Altium Designer’s unified environment provides all of the tools you need into one place. Beginning with the schematic in the project directory your circuits are captured and your nets are defined. Rules and constraints may be set here that will port to the PCB layout environment keeping your layout designer informed. Mechanical drawings easily import into the unified environment so board outlines begin from their origin. Component libraries are shared rather than being ad hoc amongst differing EDA tools for the same board. With component libraries linked across the enterprise, your circuit designers can select readily-accessible parts early in the design cycle keeping the printed circuit board layout relevant by the time it is released to manufacture. Routing nets is sophisticated with unified tools for impedance calculations. Planes are set early in the layer stack manager so high-speed signals can be routed on stripline adjacent to the ground plane.

Don’t drop your PCBs back down to printed wiring board days. Let strong PCB design software handle the tough work of your PCB for you. Altium Designer is the best tool on the market to design and produce your printed circuit board for today’s electronic market.

About Author

About Author

Zachariah Peterson has an extensive technical background in academia and industry. He currently provides research, design, and marketing services to companies in the electronics industry. Prior to working in the PCB industry, he taught at Portland State University and conducted research on random laser theory, materials, and stability. His background in scientific research spans topics in nanoparticle lasers, electronic and optoelectronic semiconductor devices, environmental sensors, and stochastics. His work has been published in over a dozen peer-reviewed journals and conference proceedings, and he has written 1000+ technical blogs on PCB design for a number of companies. He is a member of IEEE Photonics Society, IEEE Electronics Packaging Society, and the American Physical Society, and he currently serves on the INCITS Quantum Computing Technical Advisory Committee.

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