PCB design considerations and tools

Correct printed circuit board (PCB) design is critical to producing electronic prototypes with operational and commercial efficiency. This is especially true for embedded applications. The size and type of embedded circuits vary by microprocessor, component, and operating system, but most importantly is the complexity of the software, whose code ranges from a few hundred bytes to several megabytes.

Based on the developed circuit diagram, the simulation and design of the PCB can be performed by exporting the Gerber/drill file. Whatever the design, engineers need to know exactly how the circuits (and electronic components) should be laid out and how they will work. For EE, finding the right software tools for PCB design can be a daunting task. Software tools that work for one PCB project may not work well for others. EE requires intuitive board design tools that include useful features, are stable enough to limit risk, and have a robust library that makes them suitable for multiple projects.

Hardware problem

For projects targeting the Internet of Things, where integration is central to performance and reliability, the integration of conductive and non-conductive materials in PCBS requires the iot designer to investigate the interaction between various electrical and mechanical aspects of the design. In particular, as component sizes continue to shrink, electric heating on PCBS becomes an increasingly important factor. At the same time, functional requirements are rising. In order to achieve the merit based performance of the design, the temperature response, the behavior of the electronic components on the board, and the overall thermal management are critical to the function and reliability of the system.

PCB must be isolated to ensure protection. Prevent short circuits by protecting the copper stitches placed on the circuit board to create the electronic system. FR-4 is a better base material than low-cost alternatives such as synthetic resin bonded paper (SRBP, FR-1, FR-2) because of its physical/mechanical properties, especially the ability to retain data at high frequencies, its high heat resistance, and lower water absorption than other materials. The FR-4 is widely used in high-end construction as well as industrial and military equipment. It is compatible with ultra high insulation (ultra high vacuum or UHV).

But FR-4 as a PCB substrate faces a number of limitations due to the chemical treatments used in production. In particular, the material is prone to forming inclusions (bubbles) and streaks (longitudinal bubbles), as well as glass fabric deformation. These defects can lead to inconsistent dielectric strength and impair PCB wiring performance. The new epoxy glass material solves these problems.

Other commonly used materials are polyimide/fiberglass, which supports higher temperatures and is tougher, and KAPTON, which is flexible and lightweight for applications such as monitors and keyboards. Factors to be considered when selecting dielectric materials (substrate) include coefficient of thermal expansion (CTE), glass transition temperature (Tg), thermal conductivity and mechanical stiffness.

Military/aerospace PCBS require special design considerations based on layout specifications and 100% testable design (DFT) coverage. The MIL-STD-883 standard establishes testing methods and procedures for microelectronic devices applicable to military and aerospace systems, including mechanical and electrical testing, manufacturing and training procedures, and other controls to ensure uniform industry-wide levels of quality and reliability for the various applications of such devices.

In addition to meeting various standards, the design of automotive system electronics must follow a series of rules, such as the AEC-Q100 mechanical and electronic test for packaging integrated circuits. Crosstalk effect can affect vehicle safety. To minimize these effects, PCB designers must impose a minimum distance between the signal line and the power line. Design and standardization are facilitated by software tools that automatically highlight aspects of the design that require further modification to meet interference limitations and heat dissipation conditions to avoid compromising system operation.

Interference from the circuit itself is not the only threat to signal quality. The PCB in the car is bombarded by noise, which interacts with the body in complex ways to induce unwanted current in the circuit. Voltage spikes and fluctuations caused by automotive ignition systems can cause components to exceed their machining tolerances.

Software problem

Today's PCB layout tools must have a combination of functions to meet the requirements of designers. Choosing the right layout tool should be the first consideration in PCB design and should never be ignored. Products from Mentor Graphics, OrCAD Systems, and Altium are among the most popular PCB layout tools available today.

Altium Designer is one of the most popular high-end PCB design packages on the market today. It has automatic wiring function, support line length adjustment and 3D modeling. Altium Designer includes tools for all circuit design tasks, from schematic capture to HDL and circuit simulation, signal analysis, PCB design, and FPGA embedded development.

Mentor Graphics' PCB layout platform addresses the major challenges facing today's system designers: accurate, performance - and reuse-oriented nested planning; Efficient routing in dense and complex topologies; And mechanical and electrical optimization. A key feature of the platform, and a key innovation in the industry, is the Sketch Router, which provides designers with complete and interactive control over the automatic/assisted uncoiling process, producing the same quality of results as manual uncoiling, but in much less time.

OrCAD PCB Editor is an interactive environment for board design at any technical level, from the simplest to the most complex. Due to its true scalability against Cadence Allegro PCB Designer PCB solutions, OrCAD PCB Editor supports the technical evolution of design teams and supports managing the highest level of constraints (high speed, signal integrity, etc.) while maintaining the same graphical interface and file format.

Light drawing file

The industry standard Gerber file format is used to convey design information for PCB production. In many ways, Gerber is similar to PDFS for electronics; It's just a small file format written in a hybrid machine control language. These files are generated by the circuit breaker software and sent to the PCB manufacturer to the CAM software.

The safe integration of electronic systems into vehicles and other complex systems raises important hardware and software considerations. The engineer's goal is to minimize the number of design iterations and development time while giving designers significant advantages in implementing workflow.