PCB/PCB ASSEMBLY 's Manufacturability and Reliability for engineering design.

 
In recent years, with the continuous progress and development of science and technology, the wiring layout of PCB/PCB ASSEMBLY tends to be more precise, which has higher requirements for production, in other words, it has greater requirements for the reliability of production, and the reliability in the production process is higher, the products produced will have higher reliability. This article starts with the concept of PCB/PCB ASSEMBLY, and then.
 
The manufacturability of PCBA and the problems existing in reliability design are analyzed in detail. Finally, the effective measures to realize the manufacturability and reliability design of PCB/PCB ASSEMBLY are put forward.

 

Keywords PCB/PCB ASSEMBLY; manufacturability; reliability; design; initiative.
 
The proposal of PCB/PCB ASSEMBLY manufacturability and reliability design effectively improves the process level of circuit industry design. However, due to the lack of relatively mature theory in the research of PCB/PCB ASSEMBLY manufacturability and reliability design, there are still some human factors and technical problems in PCB/PCB ASSEMBLY manufacturability and reliability design, and the causes of the problems are analyzed. It is of great significance to propose effective improvement measures to realize the manufacturability and reliability design of PCB/PCB ASSEMBLY. Posted by Dr.jack you ,CTO,Topscom R&D Department.
 
1 the concept of PCB/PCB ASSEMBLY.
 
The so-called PCB/PCB ASSEMBLY printed circuit board is a board made of printed circuits, printed components or conductive patterns formed by a combination of the two on an insulating substrate according to a predetermined design. As the support of components and providing the electrical connection needed for the circuit work of the system, it is an important basic component to realize the miniaturization, lightweight, assembly mechanization and automation of electronic products, and is widely used in the electronic industry.
 
2 the manufacturability of PCB/PCB ASSEMBLY and the problems existing in reliability design.
 
2.1 drilling problem.
 
When the factory carries out hole processing, through mechanical operation, the engineering department provides various parameter configurations, and processes all kinds of holes on a copper clad laminate according to the drilling parameter drawing provided by the engineering department. In fact, on a PCB board, the aperture will not be exactly the same, because some holes are used as plating through holes, while some holes do not need to be plated with copper, which leads to differences in the size of the aperture. At the same time, the holes on the PCB board are millimeter units, which requires a high precision of the machine.
 
However, because the line is too dense and the distance between holes is too close, the phenomenon of hole drilling deviation occurs frequently, and it has always occupied the largest proportion of bad projects. As described earlier in the design principle, the distance from hole to line and the distance between hole and hole have a best recommended range, which should be paid attention to by designers and taken into account in the usual design. At the same time, the size of the pad also has a certain impact on this problem, for example, if the pad is designed to be wide, then even if the hole is slightly deviated, it does not affect the reliability of the PCB board. Of course, the design of the pad should take into account the layout of the whole board, because of this reason, the wiring should not exceed the allowable range of density, and cause other problems, so that it has the same or greater impact on the reliability of the PCB board.

 


2.2 the problem of sinking copper.
 
Copper deposition is a very important part of the PCB process. In PCB production, double panels and multilayer plates are the most produced plates, and the process of copper deposition is very important. It connects different levels of plates to form a whole. Therefore, the success rate of copper deposition determines the yield of PCB board production.
 
As mentioned earlier, copper deposition is mainly through chemical reactions to thicken the copper foil on the surface of the plate, leaving a thin layer of copper on the hole wall to facilitate the subsequent electroplating process. Because of the need for copper plating in the hole wall, it determines that the actual pore size is different from that at the time of design. The copper deposition is accomplished through chemical reactions, and we can only control the degree and progress of copper deposition through some parameters, such as problems, solution concentration, etc., therefore, the accuracy is not very accurate, which requires designers to fully take into account the objective difficulties in this process to design the wiring diagram of PCB, so as to make the reliable performance of the processed board reach the maximum possible range.
 
In addition, because the production of the PCB factory is large-scale rather than individual, it determines that it is impossible for workers to take care of every piece of PCB that is being produced and processed in the production process. Therefore, this requires designers to fully consider the objective difficulties in processing.
 
2.3 Engineering data issues.
 
In general, after receiving customer orders and wiring diagrams, factories need to convert them into various drawings that can be used for production, but with the development of science and technology, the wiring density of PCB is getting higher and higher and more and more sophisticated, which is a test for engineers.
 
As engineers in the engineering department, they need to restore the original wiring diagram to several different data, especially the drilling drawing. In the design, the holes are classified into different categories, and in the multilayer board, there is also the distribution of blind holes. And whether the holes need to be copper-plated. In order to improve the reliability and finished product rate in the production process of PCB, designers must be required to divide all levels clearly, all kinds of holes are clearly marked, the wiring specifications are reasonable, and operate strictly in accordance with the requirements of the design specifications, so that the design parameters can meet the standards.
 
2.4 etching problem.
 
As mentioned earlier, the etched copper line is not a standard box, which requires the designer to regard it as a trapezoidal cross section when considering the range of current intensity through the line, and for this reason, the linewidth should be more relaxed than in theory. In fact, this step has already been done in this part of the project, and designers only need to consider whether there is enough room for the engineering department to expand the line width, so there must be enough room for the distance between the two lines in the design.
 
3 effective measures to realize the manufacturability and reliability design of PCB/PCB ASSEMBLY.

 



3.1 using NC drilling technology.
 
In the production process of multilayer plate and double panel, there are three requirements for the drilling process: first, the hole position is accurate; second, the hole wall quality is good; third, the production efficiency is high.Posted by Dr.jack you ,CTO,Topscom R&D Department.
 
As the surface mounting technology of PCB takes density as the core and continues to develop to the depth of "thin and flat", one of the main methods to increase the density of surface mounting PCB is to reduce the size of the through hole, so the development trend of drilling is mainly the sharp reduction of the size of the through hole. φ 0.8mm, φ 0.5 mm, φ 0.4 mm, φ 0.25 mm, φ 0.15mm. The requirement of hole size reduction affects the development of NC drilling equipment and conditions to a better direction.
 
3.2 use electroless copper plating process.
 
The electroless copper plating process mainly includes double-panel electroless copper plating and multi-panel electroless copper plating, in which the technological process of double-panel electroless copper plating is as follows:
 
Drilling plate "deburring" cleaning adjustment treatment, "micro-etching" pre-impregnation treatment, "activation treatment" accelerated treatment "electroless copper plating. Among them, the electroless copper plating process of multi-panel is basically the same as that of double-panel, but the difference is that the multi-layer plate should be treated by drilling or etching after deburring.
 
3.3 do a good job in the review of engineering materials.
 
The role of the engineering department is mainly to convert the PCB wiring diagram provided by the user into the engineering drawings needed for the actual processing through the software. before starting production, the engineering department must examine the PCB wiring diagram provided by the customer to see if it can meet the technical indicators and parameters of the company's factory production, so as to avoid ineffective processing, waste materials, and cause damage to efficiency and profits.
 
3.4 do a good job in the construction of etching technology.
 
It is very important to choose the pattern etching method suitable for high-density printed circuit board. In particular, the function and etching mode of etching solution are the key to ensure the dimensional accuracy of circuit graphics. From the current process is still the subtraction method as the mainstream, there are two kinds of anti-corrosion layers of circuit patterns, one is organic film, the other is anti-corrosion metal coating.
 
4 concluding remarks.
 
In this paper, based on the actual production of the factory, the reliability problems in the manufacturing process are summarized and analyzed in the design. Generally speaking, in the manufacturing process, the causes of unreliability are mostly caused by equipment, manual operation and other factors in the processing process, but there is no lack of unreliability in manufacturing due to the incompleteness of the design.

Posted by Dr.jack you ,CTO,Topscom R&D Department.