Materials Are Commonly Used in PCB Fabrication
The choice of PCB materials is a crucial factor in overall design performance. The material chosen directly influences how well electrical signals travel through the circuit board, affecting all aspects of functionality and performance. There are two primary categories of PCB board materials: rigid substrate and flexible substrate. The specific material choices vary depending on project requirements and desired board properties.
Rigid substrates are typically made of fiberglass-reinforced epoxy laminates, such as FR-4. The most common build material for PCBs, FR-4 is known for its durability and excellent mechanical strength. However, some projects require a more flexible material, such as polyimide or phenolic resins. The choice of rigid or flexible PCB substrate depends on the specific application and material parameters, such as conductive layer thickness, dielectric constant and signal-transmission speed.
A flexible pcb is comprised of a base material with copper layers affixed to it using a mixture of heat and adhesive. The copper is then etched to create the circuit traces. The copper layer’s thickness and pattern are key factors in a circuit board’s flexibility, requiring special consideration during the design phase.
What Materials Are Commonly Used in PCB Fabrication?
Most of us are familiar with the green FR-4 boards to which we solder our electronics components, but there are many other PCB build materials in use. The most popular, FR-4 is a glass-reinforced epoxy laminate sheet composite that features woven fiberglass cloth and an epoxy binder. FR-4 offers superior electrical insulation, thermal stability and mechanical strength. A more cost-effective alternative to FR-4, CEM-3, is also frequently used as it offers similar electrical and mechanical characteristics.
In addition to the conductive copper, most PCBs have a solder mask layer that protects the circuit board from short circuits and other defects during assembly. The solder mask layer is usually green, but colors like blue, SparkFun red and Arduino black are also available. Above the solder mask is a silkscreen layer with letters and numbers that make a PCB easier to assemble for tech programmers.
The evolution of PCB technology has been nothing short of extraordinary, driven by relentless innovation and the insatiable demand for smaller, faster, and more capable electronics. From the rudimentary single-sided boards of the mid-20th century to the multilayered marvels of today, PCBs have undergone a metamorphosis, pushing the boundaries of what is possible in terms of performance, reliability, and complexity.
A via is a hole in a circuit board that allows a conductor to pass through the layers of the PCB. Usually, vias are empty and called blind, but in some cases they can be filled with conducting materials to boost current carrying capacity or to form barriers against dust and other impurities. On a standard PCB, most vias are tented so they can be easily soldered to, but some are untented for more advanced applications.