Here you'll find insights into PCB design, tech trends, assembly issues, and trending topics
in the general news media as they relate to printed circuit board technology.
As experts in the manufacture and assembly of printed circuit boards, we work to make our blog a helpful resource on PCB topics and the industries that we work with, including automotive, consumer electronics, aerospace and many more.
Thermal design requirements for layout; Layout signal integrity requirements; EMC requirements
Flexible printed circuit boards can be classified according to the type of bending encountered during assembly and use. There are two design types, which are discussed below:
For digital circuit designers, the inductance of the via is more important than the capacitance. Each via has a parasitic mid-inductance. Because the physical structure of the via is small, its characteristics are very lumped lumped circuit components. The main effect of the series inductance of the via is to reduce the effectiveness of the power supply bypass capacitor, which will make the overall power supply filtering effect worse.
In circuit design, we are generally concerned about the quality of the signal, but sometimes we are often limited to the signal line for research, and the power and ground as the ideal situation to deal with, although this can simplify the problem, but in high-speed design This simplification is no longer feasible. Although the direct result of circuit design is manifested in signal integrity, we must not neglect the power integrity design. Because power integrity directly affects the signal integrity of the final PCB. Both power integrity and signal integrity are closely related, and in many cases, the main cause of signal distortion is the power system. For example, the ground bounce noise is too large, the design of the decoupling capacitor is not suitable, the loop effect is serious, the division of multiple power/ground planes is not good, the design of the ground layer is unreasonable, the current is not uniform, and the like.
Qualifications and main duties.
In a company, from a product-level perspective, what are the prerequisites for a signal integrity engineer, what they are doing, and a bystander's understanding is as follows:
The characteristic impedance of the control signal transmission path is kept constant, and the reflection coefficient is 0, which means that there is no reflection on the transmission path. This is called impedance matching. At this point the signal will be ideally delivered to the terminal.
The following layered stacking scheme assumes that the supply current flows on a single layer, with single or multiple voltages distributed across different parts of the same layer. The case of multiple power planes is discussed later.
There are many ways to solve EMI problems. Modern EMI suppression methods include: using EMI suppression coatings, selecting suitable EMI suppression components, and EMI simulation designs. This article starts from the most basic PCB layout and discusses the role of PCB layered stacking in controlling EMI radiation.
Digital devices are moving in the direction of high speed, low consumption, small size, and high anti-interference. This trend has put forward many new requirements for the design of printed circuit boards. The application of Protel software in China is quite common. However, many designers only pay attention to the Protel software's routing rate. The improvements made by Protel software to adapt to the changes of device characteristics are not used in the design, which not only makes software resources. The waste is more serious, and the excellent performance of many new devices is difficult to play. This paper intends to introduce Protel for Windows V1.5 software as an example to introduce the high-frequency circuit wiring when Protel software can Some special countermeasures are provided.
We can derive the value of the characteristic impedance, which is the value of the instantaneous impedance seen by the signal during transmission.
From a battery point of view, once the design engineer connects the battery leads to the front end of the transmission line, there is always a constant value of current flowing out of the battery and keeping the voltage signal constant. Some people may ask, what kind of electronic components have such behavior? A constant current value is maintained when a constant voltage signal is added, of course the resistance.
In recent years, an increasingly important issue in the field of high-speed design has been the focus of design engineers on the design of controlled-impedance boards and the characteristic impedance of interconnects on boards.
To address signal integrity issues, the entire design process needs to be further upgraded to become a complete set of tools that can take into account multiple different effects and design assessments.
For the design of ASIC (Application Specific Integrated Circuit), the performance of standard cells is wasted due to the application of standard cells, shorter development cycle, and more relaxed protection between cells. Therefore, the key to high-end ASIC chip design is to ensure high-performance chips are delivered with shorter development time.
In SoC design, the coupling between signals can cause signal integrity problems. Neglecting signal integrity problems can lead to crosstalk between signals, and reliability, manufacturability and system performance will also be reduced.
At present, electronic equipment is used in various electronic devices and systems, and printed circuit boards are still the main assembly method. Practice has proved that even if the schematic design of the circuit is correct and the printed circuit board is not properly designed, it will adversely affect the reliability of the electronic device. For example, if the two thin parallel lines of the printed board are in close proximity, a delay in the signal waveform is formed, and reflected noise is formed at the end of the transmission line. Therefore, when designing a printed circuit board, care should be taken to use the correct method.