PCB News - Precautions for PCBA processing in electronic product design

Precautions for PCBA processing in electronic product design
In electronic design, PCBA processing is the physical carrier of our design content, and the ultimate realization of all our design intent is expressed through the PCBA processing board. In this way, PCBA processing design is an indispensable link in any project.
But in the previous design, due to the low frequency, low density, and large distance between the devices, the PCBA processing and design work is for the purpose of connection, without any other functional and performance challenges. Therefore, for a long period of time, the status of PCBA processing design in the entire project is very low. The physical connection of PCBA processing is usually done by the hardware logic connection designer. At present, there are still such development models on some small products.
The differences between today's PCBA processing and the previous ones 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 megabytes in the past, and clocks with hundreds of megabytes and gigabytes are becoming more and more common on single boards. . Due to the rapid development of chip technology, the edge rate of the signal is getting faster and faster. At present, the rising edge of the signal is about 1 ns. This will cause system and board-level SI and EMC problems to become more prominent;

2. The integration scale of circuits is getting larger and larger, and the number of I/Os is increasing, which makes the interconnection density of single boards continue to increase; as functions become more and more powerful, the integration of circuits is getting higher and higher. The level of chip processing technology is getting higher and higher. The DIP package in the past has almost disappeared on the current single board, and the small-pitch BGA and QFP have become the mainstream package of chips. This makes the density of PCBA processing and design increase accordingly.
3. The continuous reduction of product development and market launch time makes us face the severe challenge of one-time design success; time is cost, and time is money. In a field where electronic products are updated very quickly, the window of opportunity for profit will be much larger if the product is launched one day sooner.
4. Because PCBA processing is the physical carrier of product realization. In high-speed circuits, the quality of PCBA processing is related to the function and performance of the product. The same devices and connections, different PCBA processing carriers, their results are different.
Therefore, the design process is slowly changing. In the past, the logic function design in the design 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 PCBA processing design part is also occupied. 50% of the time. Experts predict that in future designs, the logic function overhead of the hardware will become smaller and smaller, and the high-speed PCBA processing design overhead such as developing design rules will reach 80% or even higher.
All these are just explanations. PCBA processing design will be the focus and difficulty in current and future design.
Our PCBA processing design mainly focuses on the following points:
1. Realization of function
2, stable performance
3, easy processing
4, the beauty of the veneer
The realization of function is the first step of our PCB processing. In the past design, because the signal edge rate and clock frequency are relatively low, as long as the logical connection is correct, the physical connection will not affect the performance of use. But this view is not used in the current design. There is an example to illustrate this point:
The circuit board designers of a well-known American manufacturer of image detection systems have recently encountered a peculiar thing: a product that has been successfully designed, manufactured and put on the market 7 years ago has been able to work very stably and reliably. However, the products that have been rolled off the production line recently have problems, and the products cannot operate normally.