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.
1. Impedance matching refers to the proper matching between the signal source or transmission line and the load. According to the access mode, there are two modes of impedance matching: serial and parallel; according to the source frequency impedance matching, it can be divided into low frequency and high frequency.
PCB design techniques have an impact on the following three effects:
In high-speed designs, the characteristic impedance of the controllable impedance plates and lines is one of the most important and common problems. First, let's look at the definition of a transmission line: a transmission line consists of two conductors of a certain length, one for transmitting signals and the other for receiving signals (remember that the "loop" replaces the concept of "ground"). In a multi-layer board, each line is part of the transmission line and the adjacent reference plane can be used as a second line or loop. The key to a line becoming a "perfect" transmission line is to keep its characteristic impedance constant throughout the line.
The design performance of multi-layer boards is mostly similar to single-panel or double-panel, which is to avoid avoiding too many circuits to fill too small space, resulting in impractical tolerances, high inner layer capacity, and possibly even dangerous products. Quality safety. Therefore, the performance specification should consider the complete evaluation of the thermal shock, insulation resistance, welding resistance, etc. of the inner layer. The following sections describe important factors that should be considered in the design of multilayer boards.
One of the main purposes of the design of the circuit schematic is to provide a network table for the design of the PCB board and to prepare the basis for the design of the pcb board.
In the design of the PCB, in fact, before the formal wiring, it has to go through a very long step, the following is the main design process:
The PCB manufacturing process begins with a "substrate" made of Glass Epoxy or similar material.
Printed circuit boards (PCBs) appear in almost every electronic device. If there are electronic parts in a certain device, they are also mounted on different sizes of PCB.
Total 7 things.
Signal integrity issues can cause problems when you struggle to stabilize the various signals on the board. The IBIS model is an easy way to solve these problems. You can use the IBIS model to extract some important variables for signal integrity calculations and finding solutions for PCB design. The various values you extract from the IBIS model are an integral part of signal integrity design calculations.
If you find that the design experience accumulated in the previous low-speed era does not seem to work now, the same design, no problem before, but now can not work, then congratulations, you have encountered the core problem in hardware design: signal integrity . It is a good thing for you to meet one day earlier. In the past low-speed era, the signal rise time is longer when the level jumps, usually a few ns. Interconnects between devices do not affect the functionality of the circuit, and there is no need to care about signal integrity issues. But in today's high-speed era, with the increase in IC output switching speed, many are in the picosecond level, and almost all designs have encountered signal integrity problems regardless of the signal period. In addition, the pursuit of low power makes the core voltage lower and lower, 1.2v core voltage is already very common. Therefore, the noise margin that the system can tolerate is getting smaller and smaller, which makes the signal integrity problem more prominent.
Many signal integrity problems are caused by short signal rise time. This article talks about a basic concept: the relationship between signal rise time and signal bandwidth.
Via is one of the important components of a multi-layer PCB. The cost of drilling is usually 30% to 40% of the cost of PCB board. Simply put, each hole in the PCB can be called a via. From the perspective of function, the vias can be divided into two categories:
1. Printed circuit board size and device layout. 2. Decoupling capacitor configuration. 3. The heat dissipation design. 4. Electromagnetic compatibility design. 5. Ground wire design.
The design of the high-frequency circuit PCB is a complicated process, and many factors involved may directly affect the performance of the high-frequency circuit. Therefore, designers need to continuously research and explore in the actual work, accumulate experience, and combine the new EDA (Electronic Design Automation) technology to design high-performance circuit PCB with excellent performance.
Routing is the overall requirement for high-frequency PCB design based on a reasonable layout. Wiring includes both automatic routing and manual routing. Generally, regardless of the number of critical signal lines, these signal lines are manually wired first. After the wiring is completed, these signal lines are carefully inspected, fixed after inspection, and then automatically routed to other wirings. That is, the combination of manual and automatic wiring is used to complete the wiring of the PCB.
Although Protel99SE has the function of automatic layout, it can not fully meet the working needs of high-frequency circuits. It is often necessary to rely on the designer's experience. According to the specific situation, the manual layout method is used to optimize the position of some components, and then combined with automatic layout. Complete the overall design of the PCB. The rationality of the layout directly affects the life, stability, EMC (electromagnetic compatibility) of the product, etc., must be from the overall layout of the circuit board, the feasibility of wiring and the manufacturability of the PCB, mechanical structure, heat dissipation, EMI (electromagnetic Comprehensive considerations such as interference), reliability, and signal integrity.
Designers may design odd-numbered printed circuit boards (PCBs). If the wiring does not require an extra layer, why use it? Isn't reducing layers not making the board thinner? If the board is one less layer, is the cost lower? However, in some cases, adding a layer will reduce the cost.