Printed circuit boards (PCBs) are the building blocks of most modern electronics. Consisting of conductive pathways or “traces” on an insulative backing, they provide routes for electrical signals. Electricity can travel through a PCB’s traces. While they may sound simple enough, however, there are probably some things about PCBs you didn’t know.
#1) Copper Is Typically Used for Conductive Traces
While PCBs are available in different materials, most use copper for their conductive traces. Copper is the second-most conductive metal on the planet, surpassed only by silver. With its conductive properties, electricity can flow through copper traces with minimal resistance.
#2) Some PCBs Are Less Than 1 Millimeter Long
Advancements in fabrication have paved the way for very small PCBs. There are now PCBs that measure less than 1 millimeter long. In 2015, for instance, researchers at the University of Michigan designed a working PCB measuring just 0.04 millimeters long. Small PCBs are commonly used in smartphones, smartwatches, medical devices and other small electronics with limited space.
#3) Available in Rigid and Flex Versions
There are two primary types of PCBs: rigid and flex. As the names suggest, rigid PCBs are stiff, whereas flex PCBs are flexible. Flex PCBs are often made of polyimide, which is known for its flexible properties. They can bend without breaking or succumbing to permanent deformation, making them ideal monitors and other devices with folding screens or components.
#4) Can Feature Multiple Layers
While some PCBs consist of a single layer with etched conductive traces, others feature multiple layers. They essentially have two or more layers of conductive traces stacked together. The number of layers varies depending on the complexity of the PCB and the application for which it’s used. In aerospace and defense, for instance, highly complex PCBs may feature up to 50 layers.
#5) Through-Hole vs Surface Mounting
PCBs support two main methods of attaching electronic components: through-hole and surface mounting. With through-hole mounting, the components are inserted into holes drilled into the PCB. With surface mounting, components are directly attached to the PCB’s surface. Surface mounting allows for smaller and lighter devices, making it preferable for most applications.
#6) Features Copper Foil
There are different ways to design PCBs, but one of the most common methods involves copper foil. A thin layer of copper foil is laminated onto the PCB. Once in place, the copper foil is etched to create the conductive copper traces. Electricity will be confined to these traces, ensuring it will reach the connected components.