Line impedance

For the battery, a continuous 0.06-inch line segment is charged every 0.01 nanosecond as the signal travels along the line. When a constant current is obtained from the power source, the transmission line looks like an impedance and has a constant impedance value, which can be called the "surge impedance" of the transmission line.

Similarly, as the signal travels along the line, which current will increase the voltage of this step to 1 volt within 0.01 nanosecond before the next step? This brings us to the concept of instantaneous impedance.

When viewed from the cell's point of view, if the signal travels at a steady rate along the transmission line and the transmission line has the same cross section, the same amount of charge is required for each step forward in 0.01 nanosecond to produce the same signal voltage. When advancing along this line, the same instantaneous impedance is created, which is treated as a property of the transmission line, known as the characteristic impedance. A transmission line may be considered a controllable impedance line if the characteristic impedance of the signal is the same at each step of the transmission process.

Instantaneous impedance, or characteristic impedance, is very important for the quality of signal transmission. During the transfer process, if the impedance of the next step is equal to that of the previous step, the work will proceed smoothly, but if the impedance changes, there will be some problems.

In order to achieve the best signal quality, the design goal of the internal connection is to keep the impedance as stable as possible during the signal transmission process. First, the characteristic impedance of the transmission line must be kept stable. Therefore, the production of controllable impedance boards is becoming more and more important. In addition, other methods such as minimization of residual line length, terminal removal and the use of whole line are also used to maintain the stability of instantaneous impedance in signal transmission.

Calculation of characteristic impedance

8. The activity of copper settling liquid is too strong:

The high content of three components in the newly opened cylinder or tank of copper settling liquid, especially the high content of copper, will lead to the excessive activity of the tank liquid, the coarse deposition of copper, hydrogen, cuprous oxide in the chemical copper layer caused by excessive inclusion in the coating physical quality decline and poor binding force. Can be appropriate to take the following methods can be: reduce the copper content,(to the tank to add pure water) including three components, appropriate to improve the complexing agent and stabilizer content, appropriate to reduce the temperature of the tank;

9. In the process of graphic transfer, insufficient washing after development, too long placement time after development or too much dust in the workshop will cause poor cleanliness of the board, and the fiber treatment effect is slightly poor, which may cause potential quality problems;

10. There is organic pollution in the plating tank, especially oil pollution, which is more likely to occur in the automatic line.

11. Copper plating pre-leaching tank should pay attention to timely replacement, too much pollution in the tank, or too high copper content, will not only cause the cleanliness of the board, but also cause rough surface defects;

12. In addition, in winter, when the tank liquid in some factories is not heated, special attention should be paid to the live into the tank of the production process, especially the plating tank with air stirring, such as copper nickel; For nickel cylinder in winter, it is best to add a warm water bath before nickel plating,(the water temperature is about 30-40 degrees), to ensure that the initial dense nickel layer deposition is good;

In the actual production process, there are many reasons for the surface bubbling, the author can only do a brief analysis, for different manufacturers of equipment technical level may appear different reasons caused by the bubbling phenomenon, the specific situation to be specific analysis, not generalize, copy rigid; The analysis of the above reasons is not primary, secondary and important, basically according to the production process to do a brief analysis, in this series, just to provide you with a direction to solve the problem and a broader vision, I hope to everyone's process production and problem solving, can play a role in attracting jade!

Just adagio (soft and hard combined board) knowledge

The essence of rigid pliable board is to FPC as a PCB layer or two circuit layer, and then to the PCB rigid part of milling processing, only retain the flexible part.

What is a hard and soft board

The birth and development of FPC and PCB gave birth to the new product of the combination of soft and hard board. Therefore, the combination of soft and hard board, is the Flexible circuit board and hard circuit board, after pressing and other processes, according to the relevant process requirements combined together, the formation of a circuit board with FPC characteristics and PCB characteristics.

Advantages and disadvantages:

Advantages: The combination of soft and hard board has the characteristics of FPC and PCB at the same time, so it can be used in some products with special requirements, both flexible and rigid areas, to save the internal space of the product, reduce the volume of finished products, improve the product performance is of great help.

Disadvantages: the combination of soft and hard board production process is many, the production is difficult, the rate of good products is low, the material, manpower is more, therefore, the price is more expensive, the production cycle is longer.

1, rigid adagio is not cheap, why the use of rigid adagio?

In hardware design, cost is often not the key factor;

First, reliability: rigid adagio can solve the installation reliability problem of FPC.

Connecting through connectors in FPC brings installation cost, installation inconvenience, installation reliability problems, and easy to short circuit, fall off and other problems. In the design of a mass-shipped barrel machine of Hikvision, we can see the phenomenon of repairing welding between FPC and PCB after the installation of FPC. Rigid adagio solves the problem of reliability of FPC installation.

Second, comprehensive cost:

Rigid adagio, although the price per unit area is increased, but saves the cost of connector, at the same time reduces the installation time, reduces the repair rate, reduces the repair rate, improves the productivity and reliability. The use of products in mass shipments is often effective in reducing costs.

So the calculated cost:

Area of rigid pliable * unit price of rigid pliable - processing time cost - FPC loose repair cost * Loose probability - whether the management cost brought by fewer types of boards is greater than the original PCB area * unit price of PCB +FPC price + connector price

Third, effectively improve signal quality

Because the connection is not made through a connector, the wiring continuity is better and the signal integrity is better.

Traditional IPC uses FPCS and connectors to connect the Sensor board to the main control board.

Just adagio (soft and hard combined board) knowledge

The rigid flexible plate can be used to integrate the main control board and sensor board, which solves many problems and meets the structural design requirements of the barrel machine.

Just adagio (soft and hard combined board) knowledge

2, rigid adagio design points:

A. It is necessary to consider the bending radius of the flexible plate. Too small A bending radius will be easy to damage.

B, effectively reduce the total area, optimize the design to reduce the cost.

C. The structure of the three-dimensional space after installation needs to be considered.

D. It is necessary to consider the optimal design of the number of lines in the flexible part.