Despite the increasing semiconductor integration, the availability of on-chip systems for many applications, and the increasing ease of access to a number of powerful, out-of-the-box development boards, many electronic applications in use cases still require custom PCBS. Even a normal PCB can play a very important role in one-off development.
PCB is the physical platform for design and the most flexible part for electronic system design of original components. This article will introduce several golden rules of PCB design, most of which have not changed since the birth of commercial PCB design 25 years ago, and are widely applicable to various PCB design projects, both for young electronic design engineers and more mature PCB manufacturers.
Rule 1: select the correct grid
Set and always use grid spacing that matches the most elements. Although the multi-grid seems to be effective, if engineers can think more about it in the early stage of PCB layout design, they can avoid the problem of spacing setting and apply the circuit board to the maximum extent. Since many devices come in multiple package sizes, engineers should use products that are best suited to their design. In addition, polygon is very important for PCB to apply copper, polygon filling deviation is generally generated when polygon is applied to copper, although it is not as standard as a single grid, it can provide more than the required circuit board service life.
Rule 2: keep the path shortest and most direct
This may sound simple, but it should be kept in mind at every stage, even if it means changing the circuit board layout to optimize the wiring length. This is particularly true for analog and high-speed digital circuits, where performance is always partially limited by impedance and parasitic effects.
Rule 3: use the power layer to manage the distribution of power and ground as much as possible
Power layer copper is a faster and simpler option for most PCB design software. By sharing a large number of conductors, the supply of the most efficient and least impedance or pressure drop current is guaranteed, along with sufficient grounding backflow paths. If possible, multiple power supply lines can be run in the same area of the circuit board to confirm whether the ground layer covers most of the layers of a PCB layer, which is conducive to the interaction between the running lines on the adjacent layers.
Rule 4: integrate component values
As a designer, you will choose discrete components that are high or low in value but have the same performance. By integrating within a smaller standard value range, the bill of materials can be simplified and the cost can be reduced. If you have a range of PCB products based on preferred device values, it will be better for you to make the right inventory management decisions in the long run.
Rule 5: flexible screen printing
Silkscreen printing can be used to mark all kinds of useful information for future use by circuit board makers, service or test engineers, installers or equipment debuggers. Not only clearly label the functions and test points, but also the direction of the components and connectors as much as possible, even if the comments are printed on the underside of the components used on the board (after the board is assembled). Making full use of screen printing on the upper and lower surface of the circuit board reduces duplication of work and streamlines the production process.
Rule 6: decoupling capacitance must be selected
Do not attempt to optimize your design by avoiding decoupling of the power cord and relying on the limits in the component data sheet. Capacitors are cheap and durable, and you can spend as much time as possible assembling the capacitors in accordance with rule 6, using a standard value range to keep them in stock.
As circuit design sharing becomes more extensive and the internal team relies more and more on reference design, basic rules like these will remain a feature of PCB design, which we believe is very important for PCB design. With these basic rules in mind, developers can be very flexible to increase the value of their products and maximize the benefits from the boards they manufacture. Even novice circuit board designers, keeping these basic rules in mind can speed up the learning process and increase confidence.