Printed Circuit Board

Printed circuit boards, often called PCBs for short, are typically firm boards used for electrical circuitry. The boards are laminated stacks of layered sheets of insulating material and copper foil with components on a substrate. With endless design possibilities, you can find PCBs in electronic devices in almost any industry including in medical devices, consumer electronics, automotive components, telecommunications equipment and more.

The design of the PCB is critical to the overall performance of the end-use or system. Modern printed circuit boards are complex, multi-layered and require design coordination from concept to manufacturing to ensure reliability and performance standards.

Printed circuit boards being created on an assembly line

A printed circuit board (PCB) is a laminated stack of layered sheets of insulating material and copper foil on a substrate.

What are printed circuit boards (PCBs) made of?

Printed circuit boards generally consist of laminate sheets, substrates, etched copper, and electronic components. The materials used for laminate sheets and substrates vary depending on requirements and end-use.

Types of PCBs include single-sided, double-sided, and multi-layer and are reflective of the number of copper layers.

  • Laminate sheets are manufactured by using temperature and pressure to cure resin and layers of cloth or paper. The types of resin and layers of material determine the type of laminate. PCB manufacturers use different types of laminates depending on end-use requirements (RoHS compliancy, fire retardancy, strength, expansion, etc.).

  • Substrates are composed of electrically insulated composite materials that can transmit electric force without conduction. They are also classified on key characteristics such as thermomechanical and electrical.

  • Copper layers are etched and serve as the conductive layer to provide controlled, reliable electrical connections between electronic components.

  • Electronic components are typically soldered onto layers in specific spots and connected via the etched copper layer, transforming the PCB into a PCBA.

What’s the difference between printed circuit boards (PCBs) and printed circuit board assemblies (PCBA)?

While the terms are often interchanged, there is a technical difference. A PCBA is a completed PCB (electrical circuitry) with all the addition of required electronic components needed for the board to function as designed. A PCBA includes components such as resistors, integrated circuits (ICs) and capacitors, varying based on the intended final use and requirements.

The two primary methods to build PCBAs include:

  • Surface-mount technology (SMT) involves mounting electrical components directly onto the surface of a PCB. Electronic components mounted via SMT are called surface-mounted devices (SMD).

  • Through-hole (or thru-hole) technology involves drilling holes through PCBs and placing component leads through the holes. The leads are then soldered to pads on the opposite side.

How are printed circuit boards (PCBs) designed?

Engineers build printed circuit boards with PCB design software

Printed circuit board designers decide how to best layout and build PCBs. Designers consider not only consider the intended function of the PCB, but also how it will be used, the assembly process, and any external factors that may impact how it performs (environmental conditions or electromagnetic interference (EMI)). Designers build schematics to show how everything is positioned and connected on a PCB. Once the design is ready, it moves to review and testing, updating iteratively as needed to ensure the best design available moves to manufacturing.

The role of PCB design software is increasingly important to help check PCB designs (schematics, components and routing) against design requirements and end-use. Managing power, performance, and area (PPA) is also important as PCB designs increase in complexity. With the aid of PCB design software, designers can balance PPA against the design requirements much faster.

What are printed circuit boards (PCBs) used for?

Electronics in nearly every industry rely on printed circuit boards from home appliances to cell phones and other consumer electronics.
  • Telecommunications equipment: cell phone towers, office equipment and LED displays

  • Medical devices: medical imaging, heart rate monitors, glucose monitors and pacemakers

  • Industrial power equipment: DC-to-AC inverters, measuring equipment and manufacturing equipment

  • Home appliances: refrigerators, microwaves, washing machine and coffee makers

  • Automotive components: blind spot monitors, parking assist systems, fuel regulators and navigation systems

  • Aerospace applications: communication equipment, power supplies and pressure sensors

  • Safety equipment: security cameras, smoke detectors and electronic door locks

  • Personal electronics: televisions, smartphones, tablets, smartwatches and video game consoles