What is a PCB?

Did you know that the global market for printed circuit boards (PCBs) is projected to reach over $80 billion by 2024? This staggering figure underscores the crucial role that PCBs play in the world of electronics. From powering your smartphone to driving the latest medical devices, PCBs are the backbone of countless technologies. So, what is a PCB, and why is it so significant? So, let's delve straight into the fascinating world of PCB engineering and explore the basics of printed circuit boards.

What is a PCB?

At its core, what is a PCB? It's a platform—usually a flat, insulating material—that electrically connects electronic components using pads, conductive tracks, and other features etched from copper sheets laminated onto a non-conductive substrate. PCBs are available in many types: single-sided with a copper layer, double-sided with copper layers on both sides of the substrate, and multi-layered, which consists of multiple copper layers sandwiched within the substrate. Complex hardware such as computers require multi-layered PCBs to accommodate increased functionality.

The Evolution of PCBs

The evolution of PCBs is marked by significant milestones and notable contributions from various inventors. The concept of a PCB can be traced back to the early 20th century when conductive inks were developed to create  electrical paths on insulating materials, pioneered by Charles Ducas in 1925. This early idea laid the groundwork for future developments in the innovative PCB technology.

A major advancement came from Paul Eisler, who, in the 1930s, introduced the technique of etching circuits onto a non-conductive base, enhancing the functionality of PCBs. Eisler's innovations paved the way for mass production of electronic devices like radios and, later, televisions and computers.

The post-World War II era saw rapid advancements in PCB technology. During the 1950s, through-hole technology allowed for components to be mounted on one side of the board and soldered to the other, facilitating more compact and reliable designs. This era also marked the introduction of the integrated circuit in the 1960s, which greatly increased the overall density and capability of PCBs.

The late 20th century brought further innovations, such as surface-mount technology in the 1980s, which allowed components to be directly mounted on the surface of the board, leading to smaller and more efficient PCB designs. Additionally, advancements in materials and manufacturing processes throughout the 1990s and into the new millennium have continued to expand the applications and capabilities of PCBs in various industries, including modern electronics, automotive, and aerospace.​

PCB Engineering: How PCBs are Made

From the initial design to the final assembly, making a PCB is a complex process involving multiple steps. Let’s explore each step to appreciate the engineering marvel that a PCB is.

1. Designing the Blueprint: The making of PCB starts with the design phase. Engineers use specialized software to create a blueprint of the board. This stage is crucial, as it dictates the arrangement of the circuits and the placement of components that will later be housed on the PCB. The software allows designers to lay out the electrical connections and ensure that they meet the required specifications.
2. Preparing the Substrate: Once the design is finalized, the physical making of the PCB starts with the preparation of the substrate, usually made of a material called FR4—a type of flame-resistant fiberglass. This substrate provides the structural support for the PCB’s durability. The substrate is cut to size and cleaned to prepare for the application of copper, which will form the conductive paths.
3. Etching the Copper: The next step is to apply a thin layer of copper on one or both sides of the substrate. The areas of copper that form the circuit layout are protected with a temporary mask—usually, a photoresist applied by a process similar to photo development. The exposed copper that is not part of the circuit design is then etched away using a solution, revealing the intended pattern.
4. Applying the Solder Mask: After “etching the copper” is complete, the board is thoroughly cleaned, and a solder mask is applied over the entire surface except for the pads where components will be soldered. This mask prevents accidental contacts or solder bridges during the soldering process, which could cause shorts. The solder mask is typically green, which is why most PCBs appear green.
5. Placing the Components: The next phase in the making of PCB involves placing components onto the prepared PCB. This can be done manually for prototypes or using automated machines for mass production. Each component must be precisely placed according to the design specifications.
6. Soldering and Testing: Once all components are placed, they are soldered to the board to establish firm electrical connections. Following soldering, the PCB undergoes a QA to check for any electrical faults like shorts or open circuits. This ensures that the PCB functions correctly in its intended device.
7. Final Inspection and Assembly: The final step is a thorough inspection for any physical and functional defects in the PCB. Once cleared, the PCBs are either shipped as standalone products or assembled into the final electronic device, ready to breathe life into the technology it powers.

Through this detailed process, PCBs are transformed from simple designs on a screen into vital components that power the devices we rely on daily. Each step in PCB engineering contributes to the high standard of quality that modern electronics demand.

Future of PCBs

The future of PCB engineering is as dynamic as it is innovative. Advances in PCB technology continue to pave the way for smaller, more powerful devices. Emerging technologies, such as flexible PCBs, open new possibilities for wearable technology. Additionally, the rise of IoT (Internet of Things) devices propels the demand for customized PCBs designed to perform specific functions.

In conclusion, now that we've explored what is a PCB, it's clear that these compact components are monumental in both scope and function. In simple words, they are the unsung heroes behind the scenes, driving the functionality of nearly all modern electronics. The evolution of PCB engineering promises even more sophisticated and integrated devices in the future. Whether you are a technology enthusiast or a professional in the field, understanding the printed circuit board basics offers insight into not just how our devices operate but how they're innovating the path forward in electronics.