How to ensure high performance design of PCB

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How to ensure high performance design of PCB [Copy link]

With the rapid development of electronic and communication technologies, today's PCB design faces completely new challenges that are completely different from the past. They are mainly manifested in the following aspects:

1. The signal edge rate is getting faster and faster, and the on-chip and off-chip clock rates are getting higher and higher. The current clock frequency is no longer a few megahertz as in the past. Hundreds of megahertz and even kilohertz clocks are becoming more and more common on single boards. Due to the rapid development of chip technology, the edge rate of the signal is also getting faster and faster. Currently, the rising edge of the signal is around 1ns. This will lead to more prominent system and board-level SI and EMC problems;

2. The integration scale of circuits is getting bigger and bigger, and the number of I/O is increasing, which makes the interconnection density of single boards increase continuously; as the functions are becoming more and more powerful, the integration of circuits is getting higher and higher. The processing technology level of chips is also getting higher and higher. The past DIP packaging has almost disappeared on the current single board, and small-pitch BGA and QFP have become the mainstream packaging of chips. This makes the density of PCB design increase accordingly.

3. The time for product development and market launch is constantly decreasing, which makes us face the severe challenge of one-time design success; time is cost, time is money. In the field of electronic products, which is updated very quickly, the earlier the product is released, the larger the profit opportunity window will be.

4. Since PCB is the physical carrier of product realization. In high-speed circuits, the quality of PCB is related to the function and performance of the product. The same device and connection, different PCB carriers, their results are different.

Therefore, the design process is slowly changing. In the past, the design of logic functions often accounted for more than 80% of the hardware development and design, but now this proportion has been declining. In the current hardware design, the logic function design only accounts for 50%, and the PCB design part also occupies 50% of the time. Experts predict that in future designs, the hardware logic function overhead will be smaller and smaller, while the overhead of high-speed PCB design such as development design rules will reach 80% or even higher.

All of this just shows that PCB design will be the focus and difficulty in current and future designs.

Generally, we focus on the following points in PCB design:

1. Function realization

2. Stable performance

3. Easy processing

4. The beauty of the single board

Function realization is the first step of our PCB. In the past designs, due to the low signal edge rate and clock frequency, as long as there is no error in the logical connection, the quality of the physical connection will not affect the performance of the use. But this view is not used in current designs. There is an example that can well illustrate this point:

Circuit board designers at a famous American image detection system manufacturer recently encountered a strange thing: a product that had been successfully designed, manufactured and launched on the market seven years ago had always been able to work very stably and reliably, but recently a product that rolled off the production line had problems and could not operate normally.

Therefore, the true logical connection cannot make the function truly realized. The quality of physical connection is also the main condition for the realization of function.

Everyone has a common understanding that the performance guarantee depends on the design of the PCB. The same logic connection, the same device, and different PCBs will have different performance test results. A good design not only has high product stability, but can also pass various demanding tests. However, an unsatisfactory design cannot achieve such an effect. In some low-end products, many manufacturers use the same chipset and similar logic connections. The only difference is the level of their respective PCB design. The difference in products is mainly reflected in the PCB design.

The ease of processing is also an important indicator of the quality of PCB design. A good PCB design is easy to process, maintain, test, and manufacture. The quality of PCB is not only related to the production efficiency of PCB processing manufacturers and SMT manufacturers, but also closely related to the convenience of our testing and debugging.

Aesthetics is also an element of PCB design. The overall beauty and grandeur make people feel comfortable when they see it. PCB is also a work of art. A good PCB will make people stop and linger.

PCB design is a comprehensive discipline, which is the product of the coordination of quality, cost, time and other aspects. There is no best in PCB design, only better. In short, the design of high-speed PCB is a serious challenge faced by the field of system design today. Whether it is the design method, design tools, or the composition of the design team and the design ideas of engineers, we need to actively and seriously deal with it.