Digital PCB Assembly Discussed in Detail

Digitization is driving our lives. Nowadays, we rely on digitized devices for their accuracy, convenience, and easy connectivity with our wearables. Although these devices have made our lives much easier, they have driven the need for digital printed circuit boards (PCBs). Having known this, you may have questions like what is a digital PCB assembly. How does it differ from analog PCBs? What are the applications of such PCBs? Read this post to know the answers and more.

 

 

Overview of Digital PCB Assembly

A digital PCB is a type of board featuring electronic components that are electronically and mechanically connected to tracks and conductive pads. A digital PCB assembly is formed using digital processes and requires additional design considerations. These PCB assemblies are used in devices that are operated at high-speed and require high computational power. Some of the best examples of digital PCB assembly applications are digital clocks, digital voltmeters, medical equipment, internet switches, IoT devices, high speed computing systems, and other digital circuits.

 

How Does Digital PCB Assembly Differ from Analog PCB Assembly?

Digital and analog PCB assembly differ across most aspects, right from ideation to project kickoff, inspection and testing and final implementation. The following pointers will help you understand it better.

● Decoupling or Bypass Capacitors: These capacitors are used in both analog and digital circuits during wiring. The capacitor is placed near to the power pin. In analog PCB designs, high-frequency signals may affect the power supply. Bypass capacitors are used to bypass them. If the signals aren’t bypassed, they may enter sensitive analog chips and induce vibrations and noise. In digital circuits, decoupling capacitors are used as mini charge reservoirs. A large amount of energy is consumed in the switching gate state. Additional storage of energy on bypass capacitors helps during the switching action. If there isn’t enough charge to perform the switching, it leads to a change in the supply voltage. These voltage variations may cause digital devices to behave incorrectly.

● Wiring: Circuit board layouts and wiring techniques are the same for analog and digital circuits, with a few exceptions. In analog designs, loops and digital signal lines in the ground plane must be separated from analog components. To accomplish this, the analog ground plane is connected to the system ground plane alone. Alternately, this can also be accomplished by keeping the analog circuits at the end of the board. This helps keep the signal paths in digital PCBs free from interference. However, this is not required in digital circuits.

● Component Placement: Every PCB features some noisy as well as quiet components. Digital circuits are subjected to high noise and the components are not affected by noise. However, in analog circuits, the components are sensitive to noise. In mixed-signal circuits where both digital and analog circuits are involved, digital signals may disrupt the harmony of analog signals. The switching power supply circuits and high clock signals must be designed cautiously to avoid interference in analog circuits.

● Return Path: The analog circuits must have a dedicated GND plane. There shouldn’t be cut-outs or vias in the return path of analog signals. Also, these signals must have a short distance path, otherwise, noise will be created. In digital circuits, trace routing is important for high-speed clock and differential signals. Thus, features such as layer thickness in PCB stack up, return path, and track width must be designed as per the standard recommendations.

● Circuit Design: Accuracy and efficiency are two factors that make analog PCB assembly expensive. These assemblies demand much effort at every stage. However, the digital PCB assembly process is much simpler and can be performed using various digital tools, which makes them easy and inexpensive.

● Automation: High-level automation is involved in both digital and analog PCB assembly. However, in digital PCB assembly, software is used to monitor and control the assembly process.