Basic introduction Chinese name: PCBA mbth: printed circuit board+assembly process: PCB blank board is mounted by SMT or DIP plug-in program essence: production process substrate: bakelite board, glass fiber board metal coating: copper-tin-gold-nickel circuit board, development history, practicality, scope, new projects, substrate, metal coating, circuit design, basic production, introduction, subtraction, addition process, lamination. DIP, industrial status, introduction, North America, Japan, Taiwan Province Province, transfer to China, application, introduction, smart phone, touch screen, PCB (printed circuit board) commonly used in computer English is an important electronic component, a supporter of electronic components, and a provider of electronic component circuit connection. Because it is made by electronic printing technology, it is called "printed" circuit board. Before the appearance of printed circuit board, the interconnection between electronic components depended on the direct connection of wires to form a complete circuit. At present, the circuit bread board only exists as an effective experimental tool, and the printed circuit board has become the absolute dominant position in the electronic industry. At the beginning of the 20th century, in order to simplify the manufacture of electronic machines, reduce the wiring between electronic parts and reduce the manufacturing cost, people began to study the method of replacing wiring with printing. In the past 30 years, engineers have continuously proposed to use metal conductors as wiring on insulating substrates. The most successful thing is that in 1925, Charles Ducas of the United States printed a circuit pattern on an insulating substrate, and then successfully established a conductor for wiring by electroplating. [1] Until 1936, Austrian Paul isler published the foil technology in Britain [1], and he used printed circuit boards in a radio device; In Japan, Shigeru Miyamoto's assistant successfully applied for a patent (patent number 1 19384)".[2] Paul. This practice is called subtraction to remove unnecessary metals; The method of Charles Ducas and Hayashi Miyamoto is to add only the required wiring, which is called the addition process. Even so, due to the high calorific value of electronic parts at that time, it was difficult to use the two substrates together [1], so there was no formal practical work, but it also made the printed circuit technology further. History of development 194 1 year, the United States used copper paste coated with talc as wiring to make proximity fuses. In 1943, Americans have widely used this technology in military radios. 1947, epoxy resin began to be used to manufacture substrates. At the same time, NBS began to study the manufacturing technology of coils, capacitors and resistors formed by printed circuit technology. 1948, the United States officially recognized the invention for commercial use. Since 1950s, transistors with low calorific value have largely replaced vacuum tubes, and printed circuit board technology has been widely adopted. Etching foil technology was the mainstream at that time [1]. 1950, Japan used silver paint as wiring on glass substrates; And copper foil is used as wiring on a paper phenolic substrate (CCL) made of phenolic resin. In [1] 195 1, the appearance of polyimide further improved the heat resistance of the resin, and the polyimide substrate was also manufactured. [1] 1953, Motorola developed a double-panel electroplating through-hole method. This method is also suitable for later multilayer circuit boards. [1] printed circuit boards are widely used. 10 years later, the technology became more and more mature in the 1960s. Since the appearance of Motorola's double panels, multi-layer printed circuit boards began to appear, which made the wiring occupy a higher proportion of the substrate area. In 1960, V. Dahlgreen made a flexible printed circuit board by sticking a metal foil film with a printed circuit in a thermoplastic. In [1] 196 1, Hazeltine Company of the United States made a multilayer board with reference to the electroplating through-hole method. [1] 1967, one of the methods of adding layers, "plating technology" was published. [1][3] 1969, FD-R made a flexible printed circuit board with polyimide. [1] 1979, Pactel published "Pactel method", which is one of the methods of adding layers. [1] 1984, NTT developed the "copper polyimide method" for thin film circuits. Siemens has developed an additional layer printed circuit board for micro-wiring substrate. [1] 1990, IBM developed the SLC. Panasonic has developed the multilayer printed circuit board of ALIVH. [1] 1996, Toshiba developed B2it multilayer printed circuit board. [1] Practicality At the end of 1990' s, many schemes of adding printed circuit boards were put forward, and the added printed circuit boards have not been put into use in large quantities until now. It is very important to develop a robust test strategy for large-scale and high-density printed circuit board components (PCBA) to ensure the consistency and function with the design. In addition to building and testing these complex components, the money invested in electronic components alone may be high-when a unit is finally tested, it may reach $25,000. Because of such high cost, the problem of finding and repairing components is now more important than in the past. Today, the more complicated assembly is probably 18 square inches, 18 floors; There are more than 2900 components up and down; Including 6000 circuit nodes; There are more than 20,000 welds to be tested. The scope is Lucent's accelerated manufacturing plant (N. Andover, MA), manufacturing and testing art-class PCBA and complete transmission system. Components with more than 5,000 nodes are our concern, because they are close to the resource limit of our existing ICT (on-line test) equipment (figure 1). We now manufacture about 800 different PCBA or "nodes". Among these 800 kinds of nodes, about 20 kinds are in the range of 5000~6000 nodes. However, this number has increased rapidly. New projects New development projects need more complex, larger PCBA and more compact packaging. These requirements challenge our ability to build and test these units. In addition, larger circuit boards with smaller components and more nodes can continue to exist. For example, the design of a circuit board diagram is being drawn. There are about 1 16000 nodes, more than 5 100 components and more than 37800 solder joints that need to be tested or confirmed. This unit also has BGA above and below, and BGA is the same as. Using traditional needle bed to test circuit boards of this size and complexity, ICT is impossible. In the manufacturing process, especially in testing, the increasing complexity and density of PCBA is not a new problem. Realizing that increasing the number of test pins in the ICT test fixture is not the direction we should take, we began to observe alternative circuit verification methods. Looking at the number of non-contact probes per million, we found that many errors (less than 3 1) on 5000 nodes may be due to probe contact problems rather than actual manufacturing defects (table 1). Therefore, we set about reducing the number of test needles, not increasing them. Nevertheless, the quality of our production process has been evaluated by the whole PCBA. We believe that the combination of traditional ICT and X-ray layering is a feasible solution. Substrate substrates are usually classified by insulating parts of the substrates. Common raw materials are bakelite, glass fiber board and various plastic boards. PCB manufacturers generally use insulating parts composed of glass fiber, non-woven fabric and resin, and then press them into "prepreg" with epoxy resin and copper foil. Common substrates and main components are: FR- 1- phenolic cotton paper, commonly known as bakelite (more economical than FR-2) FR-2- phenolic cotton paper. FR-3- cotton paper, epoxy resin FR-4- glass fiber cloth, epoxy resin FR-5- glass fiber cloth, epoxy resin FR-6- frosted glass, polyester G- 10- glass fiber cloth, epoxy resin CEM- 1- epoxy resin (non-flame retardant) CEM-3- glass. Polyester ain- AlN sic- SiC metal coating is not only the wiring on the substrate, but also the location of the circuit. In addition, different metals have different prices, which will directly affect the production cost. Different metals also have different solderability and contact, and also have different resistance values, which will directly affect the performance of components. The commonly used metal coatings are: the thickness of copper and tin is usually 5- 15μm[4], the thickness of lead-tin alloy (or tin-copper alloy) is usually 5-25μm, and the content of tin is about 63%[4]. Generally, only gold is plated on the interface [4], or silver is plated on the interface, or the printed circuit board is based on the electronic circuit diagram, and the alloy circuit with silver as a whole is designed to meet the needs of circuit users. The design of printed circuit board mainly refers to layout design, which needs to consider many factors such as internal electronic components, metal wiring, layout of through holes and external wiring, electromagnetic protection, heat dissipation, crosstalk and so on. Excellent circuit design can save production costs and achieve good circuit performance and heat dissipation performance. Simple layout design can be realized by hand, but complex circuit design generally needs the help of computer aided design (CAD). The famous design software includes Protel, OrCAD, PowerPCB, FreePCB and so on. According to different technologies, basic production import can be divided into two categories: elimination and addition. Subtraction method is to use chemicals or machinery to remove unnecessary parts from a blank circuit board (that is, a circuit board covered with a whole piece of metal foil), and the rest is the circuit that is convenient for need. Screen printing: make the pre-designed circuit diagram into a screen mask, and the unnecessary circuit parts on the screen will be covered by wax or impermeable materials. Then, put the screen mask on a blank circuit board, coat the screen with a protective agent that will not corrode, put the circuit board into an corrosive solution, and the parts not covered by the protective agent will be corroded. Finally, clean the protective agent. Photoplate: Make the pre-designed circuit diagram on a transparent film mask (the easiest way is to print the slides with a printer), then print the required parts into opaque colors, and then paint the blank circuit board with photosensitive pigments. Place the prepared film mask on the circuit board and irradiate it with strong light for several minutes. After removing the mask, the pattern is displayed on the circuit board with developer, and finally the circuit is corroded like screen printing. Engraving: Use milling machine or laser engraving machine to directly remove the unnecessary parts on the blank circuit. In the addition process, the addition process is generally to cover the photoresist (D/F) on the substrate plated with thin copper in advance, expose it with ultraviolet light, and then develop it to expose it where necessary. Then the copper thickness of the circuit on the circuit board is thickened to the required specifications by electroplating, and then a thin layer of metal tin is plated. Finally, the photoresist is removed (this process is called stripping) and the copper foil layer under the photoresist is etched away. Lamination method [1] Lamination method is one of the methods for manufacturing multilayer printed circuit boards. After the inner layer is finished, the outer layer is wrapped, and then the outer layer is processed by subtraction or addition. When the sequential lamination method is used, the operation of the lamination method is repeated, and a multilayer printed circuit board can be obtained. Laminating the inner layer (i.e. the action of bonding different layers), and the lamination is completed (subtracting the outer layer containing the metal foil film; Addition process) drilling subtraction panel electroplating The whole PCB is electroplated with a resist layer where the surface is to be preserved. The pattern electroplating method removes the barrier layer by etching to prevent it from being etched. The required surface is electroplated to a certain thickness. Remove the barrier layer by etching until the unnecessary metal foil film disappears. The addition process makes the surface completely rough. Addition process (full addition) A barrier layer is added where conductors are not needed, forming an electrolytic copper-free circuit part addition process (half). -Additives) Cover the whole PCB with electroless copper plating, add a barrier layer where there is no conductor, remove the barrier layer by electroplating copper, and etch until the electroless copper plating disappears under the barrier layer. Adding layers is one of the methods to manufacture multi-layer printed circuit boards, which, as the name implies, is to add up the printed circuit boards layer by layer. Each layer is processed into the required shape. Alivh [1] Alivh (any layer intermittent via, any layer IVA) is a layer adding technology developed by Panasonic ... it is based on aramid fiber cloth. Immerse the fiber cloth in epoxy resin to form "preg" laser drilling, fill the outer layer with conductive adhesive and paste copper foil to make circuit patterns through etching, paste the semi-finished products in the second step on the copper foil for lamination, and then repeat the fifth to seventh steps until B2IT [1] B2IT (Buried Bump Interconnection Technology) is a lamination technology developed by Toshiba. Firstly, double-faced or multi-layered boards are made, tapered silver paste is printed on copper foil, an adhesive sheet is placed on the silver paste, the silver paste passes through the adhesive sheet, the adhesive sheet of the previous step is pasted on the board of the first step, the copper foil of the adhesive sheet is made into a circuit pattern by etching, and then the second to fourth steps are repeated continuously until the production mode is introduced. SMT and DIP are both ways to integrate parts on PCB. The main difference is that SMT does not need to drill holes in PCB, while in DIP, the pins of parts need to be inserted into the holes. SMT (surface mount technology) Surface mount technology mainly uses mounter to mount some miniature parts on PCB board, and its production process is: PCB board positioning, printing solder paste, mounter mounting, reflow oven and manufacturing inspection. With the development of science and technology, SMT can also mount some large-size parts, such as some large-size mechanical parts can be mounted on the motherboard. SMT integration is very sensitive to positioning and part size, and solder paste quality and printing quality also play a key role. DIP DIP means "plug-in", that is, the parts are inserted into PCB. Due to the large size of the parts, they are not suitable for mounting or the SMT technology cannot be used in the manufacturer's production process, and the parts are integrated together in the form of plug-in. At present, there are two ways to realize manual plug-in program and robot plug-in program in the industry. The main production processes are: sticking back glue (to prevent the wrong place of tin plating), plug-in, inspection, wave soldering, printing (to remove the stains left in the furnace process) and manufacturing inspection. Briefly introduce the current situation of the industry, because the production of printed circuit boards is in the second half of electronic equipment manufacturing, it is called the downstream industry of the electronic industry. Almost all electronic equipment needs the support of printed circuit board, so printed circuit board is the product with the highest market share among electronic components in the world. At present, Japan, Chinese mainland, Taiwan Province Province of China, Western Europe and the United States are major PCB manufacturing bases. Thanks to the support of new terminal products and new markets, the global PCB market has successfully recovered and grown. According to the statistics of Hong Kong PCB Association (HKPCA), the global PCB market will develop steadily in 20 1 1 year, with an estimated growth rate of 6-9% and that of China 9- 12%. The analysis report of IEK predicts that the global PCB output value will increase by 10.36% and 438+010.50 billion USD in 2065. According to the analysis data of Pri *** ark Company and the report issued by R&D Center of Industrial Securities, the changes of PCB application structure and product structure reflect the future development trend of the industry. In recent years, with the decline in the output value of single/double boards and multi-layer boards, the output value of HDI boards, packaging boards and flexible boards has increased, indicating that the growth of HDI boards, packaging boards and flexible boards used for computer motherboards, communication backboards and automobile boards is relatively slow, while those used for "thin and short" electronic products such as high-end mobile phones and notebook computers will continue to grow rapidly. The American Printed Circuit Board Association (IPC) in North America announced that the book/bill ratio of the overall printed circuit board manufacturers in North America was 0.95 in February of 201year, which means that each product that shipped 100 in that month will only receive new orders worth $95. The B/B value was lower than 1 for the fifth consecutive month, and the industrial prosperity in North America did not substantially rebound. The Japanese earthquake will affect the supply of some PCB raw materials in the short term, which is beneficial to the transfer of production capacity to Taiwan Province Province and the mainland in the medium and long term. High-end PCB manufacturers accelerate the expansion of production in the mainland, and the transfer of technology, production capacity and orders to the mainland is the general trend. Taiwan Province Zhongshi Electronic News reported that the Japanese supply chain is broken, and the PCB factories in China and South Korea will be the big winners. According to the forecast of Taiwan Province Taiwan Province Institute of Technology (IEK), the PCB industry in Taiwan Province Province is expected to grow by 29% in 20 1 1 year, benefiting from the overall global economic recovery and consumer support from emerging countries, and will be transferred to China. According to the analysis report of China Investment Consulting, the printed circuit board industry in China will enter a period of rapid growth under the situation of domestic sales growth and global production capacity continuous transfer. By 20 14, the scale of printed circuit board industry in China will increase to 4 1.92% in the world. 3C products such as computers and related products, communication products and consumer electronics products are the main application fields of PCB. According to the data released by the Consumer Electronics Association (CEA), the global sales of consumer electronics products will reach 964 billion US dollars in 20 1 1 year, with a year-on-year increase of 10%. The data of 20 1 1 is quite close to 1 trillion dollars. China Eastern Airlines said that the biggest demand comes from smart phones and laptops, and other products with obvious sales include digital cameras, LCD TVs and other products. Smartphones According to the latest market research report released by Markets and Markets, the global mobile phone market will grow to $3410.40 billion in 20 15 years, of which the sales revenue of smartphones will reach $258.9 billion, accounting for 76% of the total revenue of the whole mobile phone market. Apple will lead the global mobile phone market with 26% market share. IPhone 4 PCB adopts any layer of HDI board and any high-density circuit board. In order to fit all the chips on the front and back of iPhone 4 on a very small PCB area, using any layer of HDI board can avoid the space waste caused by drilling holes in the machine ring and achieve the purpose of conducting any layer. With the popularity of iPhone and iPad, touch panels are popular all over the world, and predicting the touch trend will become the next growth driving engine of soft board. DisplaySearch predicts that the shipment of touch screens for tablet computers will reach 260 million pieces in 20 16, an increase of 333% over 201year. Computer Gartner analysts pointed out that notebook computers have been the growth engine of the personal computer market in the past five years, with an average annual growth rate of nearly 40%. Based on the expectation of weak demand for notebook computers, Gartner predicts that global PC shipments will reach 387.8 million units in 201/kloc-0 and 440.6 million units in 20 12, an increase of13.6 compared with 201/year. China Eastern Airlines said that in 20 1 1 year, the sales of portable computers including tablet computers will reach 220 billion US dollars, the sales of desktop computers will reach 96 billion US dollars, and the total sales of personal computers will reach 301600 million US dollars. IPad 2 was officially released on March 3, 20 1 1, and the PCB manufacturing process will adopt 4th-order Any Layer HDI. The Any Layer HDI adopted by Apple's iPhone 4 and iPad 2 will trigger an industry boom. It is expected that any layer of HDI will be applied in more and more high-end mobile phones and tablets in the future. According to the forecast of DIGITIMES Research, the global e-book shipment is expected to reach 28 million units in 20 13, with a compound annual growth rate of 38.6% from 2008 to 20 13. The analysis points out that by 20 13, the global e-book market will reach 3 billion dollars. The design trend of PCB board for e-books: first, it is required to increase the number of layers; Second, blind hole burying technology is needed; Thirdly, a PCB substrate suitable for high frequency signals is needed. ISuppli said that as the market becomes saturated, the production of digital cameras will stop in 20 14. It is estimated that in 20 14, the shipment volume will drop by 0.6% to 654.38+354 million units, and low-end digital cameras will encounter strong competition from camera phones. However, some areas of the industry can still grow, such as hybrid high definition (HD) cameras, future 3D cameras and digital monocular (DSLR) cameras. Other growth areas of digital cameras include the integration of GPS and Wi-Fi functions to improve their attractiveness and daily use potential. To further promote the flexible board market, in fact, any light and short electronic products have a strong demand for flexible boards. DisplaySearch, a LCD TV market research company, predicts that the global LCD TV shipments will reach 2150,000 units in 2065, up 13% year-on-year. 20 1 1 year, due to the gradual replacement of LCD TV backlight by manufacturers, LED backlight modules will gradually become the mainstream, which will bring technical trends to LED heat dissipation substrates: heat dissipation substrates with high heat dissipation and accurate size; Strict line alignment accuracy and high quality metal line adhesion; Thirdly, the thin film ceramic heat dissipation substrate is made by yellow lithography technology to improve the high power of LED. LED Lighting DIGITIMES Research analysts pointed out that in response to the ban on the production and sale of incandescent lamps in 20 12 years, the shipment of LED bulbs in 20 1 1 year will greatly increase, and the output value is estimated to be as high as about 8 billion US dollars. In addition, North America, Japan, South Korea and other countries will implement subsidy policies for green products such as LED lighting. As well as the high willingness of stores, shops and workshops to replace LED lighting, the global LED lighting market penetration rate has a great chance to exceed 10% in output value. 20 1 1 soaring LED lighting will definitely drive a large demand for aluminum substrates. In the next five development trends, we will vigorously develop high-density interconnection technology (HDI), which embodies the most advanced technology of contemporary PCB and brings fine wiring and micro-aperture to PCB. Strong component embedding technology-component embedding technology is a great change in PCB functional integrated circuits. PCB manufacturers need to increase resources in systems including design, equipment, testing and simulation to maintain strong vitality. PCB materials meeting international standards-high heat resistance, high glass transition temperature (Tg), low thermal expansion coefficient and low dielectric constant. Photoelectric PCB has a broad prospect-using optical path layer and circuit layer to transmit signals. The key of this new technology is to manufacture the optical path layer (optical waveguide layer). It is an organic polymer formed by photolithography, laser ablation and reactive ion etching. Update the manufacturing process and introduce advanced production equipment. With the improvement of global environmental awareness, energy conservation and emission reduction has become a top priority for countries and enterprises. As a PCB enterprise with high pollutant emission rate, it should be an important responder and participant in energy conservation and emission reduction. When manufacturing PCB prepreg, develop microwave technology, reduce the amount of solvent and energy, develop new resin system, such as water-based epoxy material, and reduce the harm of solvent; Extract resin from renewable resources such as plants or microorganisms, reduce the use of oil-based resin, find materials that can replace lead-containing solder, and develop new reusable sealing materials to ensure the recyclability of devices and packages, and ensure that long-term manufacturers must invest resources to improve the accuracy of PCB-reduce the size of PCB. Width and spatial trajectory. Durability of PCB-in line with international standards. High performance of PCB-reducing impedance and improving blind hole burying technology. Advanced production equipment. Production equipment imported from Japan, the United States, Taiwan Province Province and Europe, such as automatic plating line, gold plating line, mechanical and laser punching machine, large laminator, automatic optical inspection, laser plotter and line test equipment. Quality of human resources-including technical and managerial personnel. Environmental pollution control.