Chemical nickel palladium is an important surface treatment process in the printed circuit board industry, widely used in rigid circuit boards (PCBs), flexible circuit boards (FPCs), rigid-perturbation bonded boards and metal substrates and other production processes, and is an important development trend of the surface treatment of the printed circuit board industry in the future.
1. Types of printed circuit board surface treatment
Printed circuit boards are the basis of all electronic products, involving communications, lighting, aviation, aerospace, transportation, home appliances, military, medical equipment and other fields, so the development of the printed circuit board industry is related to the development of the entire electronics industry speed. In the printed circuit board manufacturing process, the surface treatment is one of the most important part, the more mature surface treatment process on the market at present, including spray tin (hot air leveling process), sinking tin, sinking silver, OSP (Organic Protective Sheet), electroplating hard gold / water gold, electroplating nickel gold, chemical nickel gold and chemical nickel palladium gold 8 kinds. Each process has certain advantages and disadvantages in its use, processing difficulty and cost control.
2. Surface treatment process development and application
Wireboard after surface treatment, in order to connect with other components for effective electrical properties, the main treatment process has a solder (including IC's solder ball welding) and playing the line (wire bonding) two kinds of processes.
Tin spraying, tin sinking, silver sinking and OSP surface treatment process is mainly to deal with the solder connection process, its main advantage is that the connection area is large, the speed of electrical signal transmission and transmission stability can be effectively controlled, the main disadvantage is that it can only be used in the most basic line design and electronic products, because of its limitations of the solder itself, it is difficult to cope with the fine and complex electronic circuits. Design products. Therefore, the solder connection process in the electronics industry at the initial stage of the beginning of the effective application and promotion, but with the gradual development of science and technology, part of the process has begun to be gradually eliminated, such as hot air leveling process has been used by very few companies.
Another connection process is to beat the line. Currently on the market for playing line material mainly gold wire, silver wire, palladium-plated copper wire, gold and silver alloy wire, as well as copper wire, a variety of line diameter also varies, the thick 2 mil (50um), the most fine to 0.5 mil (12um) or even finer, which the finer the diameter of the line, the finer the line to deal with the fine line of the line the more powerful.
In the above several surface treatment processes, electroplating nickel gold and chemical nickel palladium is the main response to the connection of the surface treatment process, are now widely used in the circuit board manufacturing enterprises, which electroplating nickel gold started earlier, the technology is also more mature, but at the same time because of the current market demand for the gradual enhancement of the requirements of electronic circuits, and its response to the process of higher-end products began to appear overwhelmed! At the same time, many companies began to gradually turn the treatment process to chemical nickel-palladium direction, and in order to do more recent scientific research and technological research, in order to obtain a greater degree of breakthrough.
3. Chemical nickel and palladium
Chemical nickel and palladium is the use of chemical methods in the printed line copper layer of the surface of a layer of nickel, palladium and gold, is a
non-selective surface processing technology. Its main process is degreasing - micro-etching - pre-impregnation - activation - immersion nickel - immersion palladium - immersion gold - drying, each link between the multi-stage washing for processing. The mechanism of chemical nickel-palladium-gold reaction mainly includes two kinds of oxidation-reduction reaction and replacement reaction, in which the reduction reaction is easier to cope with thick palladium and thick gold products.
At present, the production specifications of electroless nickel and palladium in general factories are as follows: nickel 2-5um, palladium 0.05-0.15um, gold 0.05-0.15um, of course, due to the difference in the equipment of the factories as well as the difference in the reaction mechanism, the homogeneity of the chemical reaction as well as the ability to cope with thick palladium and thick nickel products are also not the same.
Chemical nickel and palladium surface treatment process in the production and technical aspects of the control focus is more on the maintenance of the equipment and the stability of the potion control, the main quality problems are nickel corrosion (black plate), gold surface pollution and gold surface color.
4. Chemical nickel palladium VS electroplated nickel gold
***Similarities: 1. The same as an important surface treatment process in the field of printed wiring boards;
2. The main areas of application is to play the line connection process, to a certain extent, are able to cope with the medium- and high-end electronic circuit products.
Disadvantages: 1. Chemical nickel palladium due to the use of ordinary chemical reaction process, compared with the electrochemical reaction of its reaction rate is significantly lower;
2. The potion system is more complex, the production management and quality management requirements are higher.
Advantages:
1. Adopting the lead-free gold plating process, reducing the lead layout space, comparing with nickel-gold plating, it is more capable of coping with more precise and higher-end electronic circuits;
2. Comprehensive production cost is lower;
3. No tip-discharge effect, and it has a higher advantage in the control of the gold finger rounding rate;
4. Although the reaction rate of electroless nickel-palladium is slower, the reaction rate of the chemical reaction is lower than that of the chemical reaction. Although the reaction rate of chemical nickel-palladium-gold is slower, it does not need to be connected to the lead wire and plating line, and the number of products produced simultaneously in the same volume of the tank is much larger than that of electroplated nickel-gold, so there is a great advantage in the comprehensive production capacity.
5. Industrial model
For some large-scale circuit board manufacturing plants (such as Shennan, Jian Ding, etc.), in order to effectively respond to the needs of the order, will be within the factory to establish a special chemical nickel-palladium line to cope with the module of the process. However, due to the limitations of their own internal process equipment and for more medium-sized or small and medium-sized enterprises, due to capital, product requirements and other reasons, more factories will choose to outsource production. Outsourcing OEM market, Jin Ye Da, Yu Wei Electronics and other companies started earlier, there is the formation of a certain scale, but in response to higher demand for product production, whether in the technology to overcome or on-site management are still in a relatively basic stage, there is a longer way to go. Of course, to a certain extent, this is also with the potion of the R & D attack has a certain reason.
Based on the above market status quo, at present several from the domestic well-known board factory out of colleagues, together with the formation of the Shenzhen BOSMONT Technology Co., Ltd. dedicated to chemical nickel and palladium industry enhancement and development, the goal of the current chemical nickel and palladium market to carry out a comprehensive integration, dedicated to the process technology, on-site management and the stability of the potion to carry out a greater degree of enhancement to meet the rapidly growing market and high-tech product manufacturing needs.
6. Development trend
It has been mentioned earlier that the main advantage of chemical nickel-palladium is to deal with the surface treatment of medium and high-end products and fine lines, but the development of electronic technology and its accompanying demand is also growing rapidly, the current ordinary chemical nickel-palladium process in response to the production of high-precision lines will gradually appear to be unable to cope with, in order to cope with the higher demand, the current main direction of development is thin nickel-palladium process. Currently the main direction of development of thin nickel palladium process and chemical palladium process, of course, is still in a prerequisite stage of research and development, the specific development and promote the progress of the electronic circuit industry colleagues need to continue to work.