Ten rules that are eternal in PCB design

Despite the increasing integration of semiconductors, many applications have ready-to-use system-on-a-chip, and many powerful and out-of-the-box development boards are becoming more readily available, but the use of electronics in many use cases Still need to use a custom PCB. In a one-time development, even a common PCB can play a very important role. PCB is the physical platform for design and the most flexible component for the electronic components of the original components. This article will introduce several golden rules for PCB design. These rules have not changed since the birth of commercial PCB design 25 years ago, and are widely applicable to various PCB design projects, whether it is more mature for young electronic design engineers. Circuit board manufacturers are extremely instructive.

The following sections describe the ten most effective design rules that electronic design engineers should keep in mind when implementing design layout and commercial manufacturing using design software. Engineers do not need to implement these rules in chronological or relative importance, and they can dramatically change the product design by simply following them all.

Rule one

Select the correct grid - set and always use the grid spacing that matches the most components.

Although multi-grid seems to have significant utility, engineers can avoid problems when setting up the interval and maximize the application of the board if they can think more at the beginning of the PCB layout design. Because many devices are available in a variety of package sizes, engineers should use products that are best suited for their design. In addition, polygons are critical for board copper placement. Multi-grid boards typically produce polygon fill deviations when performing copper-clad copper. Although not as standard as a single grid, they provide the board life beyond what is required. .

Rule two

Keep the path shortest and most direct.

This sounds simple, but it should be kept in mind at every stage, even if it means changing the board layout to optimize the wiring length. This is especially true for analog and high-speed digital circuits where system performance is always partially limited by impedance and parasitics.

Rule three

Use as much as possible

The power plane manages the distribution of power and ground lines.

Rule 3: Manage the distribution of power and ground lines as much as possible using the power plane. Power layer copper is a faster and simpler option for most PCB design software. By connecting a large number of wires in a common connection, the highest efficiency and minimum impedance or voltage drop current is guaranteed while providing a sufficient ground return path. If possible, run multiple power lines in the same area of ​​the board to verify that the ground plane covers most of the layer of a layer of the PCB, which facilitates the interaction between the lines running on adjacent layers.

Rule four

Relevant components and required test points

Group together.

For example, placing discrete components required for OpAmp op amps closer to the device allows bypass capacitors and resistors to collaborate with them, helping to optimize the wiring lengths mentioned in Rule 2, while also enabling test and fault detection. It's getting easier.

Rule six

Integrate component values. As a designer, you will choose discrete components with high or low component values ​​but the same performance.

By integrating within a smaller standard value, bills of material can be simplified and costs can be reduced. If you have a range of PCB products based on your preferred device values, it will be better for you to make the right inventory management decisions in the longer term.

Rule seven

Perform Design Rule Checks (DRC) as much as possible.

Although it takes only a short time to run the DRC function on the PCB software, in a more complex design environment, as long as you perform checks during the design process, you can save a lot of time, which is a good habit to keep. Every cabling decision is critical, and you can always remind you of the most important cabling by performing a DRC.

Rule eight

Flexible use of screen printing

Rule 8: Flexible use of screen printing. Screen printing can be used to label a variety of useful information for future use by board manufacturers, service or test engineers, installers, or equipment commissioners. Not only the clear function and test point label, but also the direction of the components and connectors should be indicated as much as possible, even if these comments are printed on the lower surface of the component used on the board (after board assembly). Full application of screen printing technology on the lower surface of the board reduces duplication of effort and streamlines the production process.

Rule 9: Deselective decoupling capacitors

Do not attempt to optimize your design by avoiding decoupling the power cord and depending on the limits in the component datasheet. Capacitors are inexpensive and rugged, so you can spend as much time as possible to assemble the capacitors, while following Rule 6, using standard values ​​to keep stocks tidy.

Rule ten

Generate PCB manufacturing parameters and

Verify before submitting for production

While most board manufacturers are happy to download and verify it for you, it's best to export the Gerber file yourself and use the free viewer to check if it is as expected to avoid misunderstandings. By personally verifying, you will even find some negligent mistakes, and therefore avoid losing production by following the wrong parameters.

More dry goods waiting for you to enjoy

As circuit design is becoming more widely shared and internal teams are increasingly relying on reference designs, basic rules like the above will remain a feature of printed circuit board design, which we believe is important for PCB design. By clarifying these basic rules, developers have the flexibility to increase the value of their products and get the most out of the boards they manufacture. Even if you are new to board design, just keep these basic rules in mind to speed up the learning process and increase your confidence.