Can a PCB Circuit Board Accommodate
PCBs (printed circuit boards) have evolved significantly from their initial incarnations in the 1960s. The emergence of surface-mount technology in the 1970s allowed a much greater density of components on a board and allowed them to be arranged in parallel to each other rather than on top of one another like through-hole devices. Surface mount technology also facilitated smaller component sizes and reduced overall board size.
Initially, a pcb circuit board was designed manually by creating a photomask on clear mylar sheets at two or four times the actual board size. The photomask was used to transfer the component pin pads and their corresponding traces to the copper-clad boards. Rub-on dry transfers of common component footprints increased efficiency, and photolithographic reproduction on the mylar enabled the tracing process to be automated and computer-aided.
Today, most pcb circuit board are designed on computers using software programs such as Altium Designer or Mentor Graphics. These programs allow designers to place components on the board and route the traces in the correct locations. The design is then sent to an e-coat supplier who applies the etch resist and prepares the board for final imaging. Contact imaging still is the most popular method of image transfer, though laser direct imaging (LDI) is rapidly gaining popularity due to its lower cost.
Can a PCB Circuit Board Accommodate High-Density Interconnects?
Typical pcbs are made from dielectric composite materials such as FR-4, FR-5 or FR-A. These materials have different properties depending on the manufacturing process, and their specific properties influence signal transmission and reliability. For example, the material’s dielectric constant decreases with frequency; this causes faster edges of signals to reflect more than slower edges. The material’s dielectric breakdown voltage also influences how well the material can withstand high-frequency current gradients that can cause tracks to fail and short circuit.
For the highest level of performance and functionality, a pcb should be fabricated with Class 3 or better laminates. These have the best track record of durability and reliability in the face of vibrations, high-temperatures, humidity and other environmental conditions. Exceptional thermal stability is critical to ensure a pcb remains operational in these conditions, as well as minimizing the risk of failure at any point in time during the lifespan of the device it’s installed in.
The ability to use thinner, shorter traces and vias in HDI PCB designs increases the routing capacity and reduces crossing delays. This leads to a significant reduction in the power losses that can be encountered. This is why the technology is being adopted by many mobile and portable devices. It’s also finding widespread application in aerospace electronics, notably in missile systems and aircraft. It’s even being utilized by wearable technologies such as smart watches and virtual reality headsets. The market for HDI PCBs is expected to grow at a rapid pace over the next decade. This is due to the increasing adoption of smartphones that require small, thin circuit boards for increased function and reduced weight to improve battery life.