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Printed circuit board (PCB) is a substrate used for assembling electronic components, with a global output value of 45 billion US dollars per year. It is second only to the semiconductor industry in the electronics industry, and China's growth rate is much higher than the industry average. Nowadays, electronic products are changing rapidly, and price wars have changed the structure of the supply chain. China has both cost and market advantages. The PCB industry is gradually shifting to China due to the impact of cost and downstream industry transfer, and China is the most promising PCB market worldwide. Low end PCBs (below 4 layers) have relatively low barriers to entry, sufficient competition, and low concentration. Due to the pressure of downstream machine price reductions, product prices often face pressure from downstream manufacturers to lower prices. High end PCB (HDI, etc.) technology, equipment, processes, and other requirements are very high, with high barriers to entry and
1. The crystal structure formed by depositing gold is different from that of plating gold. Depositing gold results in a much thicker thickness of gold compared to plating gold. Depositing gold results in a golden yellow color, which is more satisfying for customers. 2. The crystal structure formed by sinking gold is different from that of plating gold, and sinking gold is easier to weld than plating gold, which will not cause poor welding and cause customer complaints. The stress of the sinking gold plate is easier to control, which is more conducive to the processing of products with bonding. At the same time, it is precisely because sinking gold is softer than plating gold, that sinking gold plates are not wear-resistant when making gold fingers. 3. The sinking gold plate only has nickel gold on the solder pad, and the signal transmission in the skin effect is in the copper layer without affecting the signal. 4. Compared to gold plating, sinking gold has a denser crystal struc
Drilling is to connect the outer circuit with the inner circuit, and the outer circuit is connected to the outer circuit. Anyway, drilling is to connect the circuits between different layers. In the later electroplating process, copper plating can be applied to the holes to connect the circuits between different layers. Some drilling holes are screw holes, positioning holes, row holes, etc., and their respective purposes are different. Drilling is to drill the required through holes on the copper clad plate. Through holes mainly provide electrical connections and serve as fixing or positioning devices. PCB through-holes are divided into two categories based on whether they are metallized or not a. Electroplated Holes (PTH), also known as Metallized Holes b. Non electroplated hole (NPTH): also known as non-metallic hole Divided by process a. Blind hole (multi-layer board) b. Buried hole (multi-layer board)
There is a very common process used in the surface treatment of circuit boards, known as the gold deposition process. In production, the cost of sinking gold plates is relatively high, and generally, sinking gold technology is not used. So how do we distinguish which type of PCB board requires sinking gold? Which type of circuit board does not require sinking gold? Analysis and judgment can be made based on the following situations. 1. The board has gold fingers that need to be plated with gold, but the layout other than the gold fingers can choose processes such as tin plating or gold plating according to the situation, which is the usual "gold plating+gold plating finger" process and "tin plating+gold plating finger" process. Occasionally, a few designers choose the full page gold plating method to achieve the goal in order to save costs or time, but the gold plating cannot reach the thickness of the plating. If the gold fingers are frequently inserted and peeled, poor connectio
A. Urea paperboard The characteristic is: the color is light yellow, commonly used for single panel, but due to being made of urea paper, it is easy to rot in cool and humid places, so it is no longer commonly used B. CAM-3 board The characteristics are: milky white color, good toughness, high CTI (600V), and only a quarter of the normal carbon dioxide emissions. It is now more commonly used in single panels C. FR4 fiberboard The characteristics are: made of fibers, with good toughness, and threads pulling each other when broken. It is commonly used in multiple panels, with a thermal expansion coefficient of 13 (16ppm/c). The mother board used in our factory is made from this board D. Multi-layer board Features: high Tg, high heat resistance and low thermal expansion rate, low dielectric constant and dielectric loss material, commonly used for four or more layers E. Soft board Features: Soft and transparent material, commonly used at the electrical connection between two b
(1) Provide mechanical support for fixing and assembling various electronic components such as integrated circuits (2) Implement wiring and electrical connections or electrical insulation between various electronic components such as integrated circuits (3) Provide the required electrical characteristics, such as characteristic impedance, etc (4) Provide solder mask graphics for automatic soldering, identifier symbols and graphics for component insertion, inspection, and maintenance 1) Reduce lead content The method of using electroplating lead and tin to produce graphic electroplating is rapidly being phased out. In the future, there will be more conversion towards panel plating (also known as panel plating) process. With the use of graphic electroplating, electroplating tin will also become mainstream. In the case of using solder, solder will be converted to lead-free materials, and there will be greater progress in this area in the future. It is expected that this transformat
The generation of a schematic diagram is generally regarded as the first step in the PCB production process, and it is also the specific implementation of product ideas by electronic engineering technicians. It is composed of many logical components (such as gate circuits, resistors, capacitors, etc. of various ICs) connected through different logic connections. Creating a schematic diagram, the source of its logical components is a large logical component library (such as TANGO PADS) contained in some CAD software. In addition to the logical component library, some CAD software can also be added by users to create new logical components (such as Cadence, Mentor, Zuken, etc.), which users can use to achieve the logical functions of the product they want to design. Due to the large number of logical components, building them in one library can easily cause confusion and be difficult to manage. Therefore, logic components with similar functional characteristics are generally placed
1. Silk screen Screen printing is the most important component in screen printing plate making, because it is the key to controlling the fluidity of ink and printing thickness. At the same time, it determines the durability of screen printing and is widely used in quality switch manufacturing technology. In addition, the excellent combination of silk screen and screen photosensitive materials is also an important factor in producing high-quality and high-precision screen printing plates. In order to ensure a good combination of the screen and photosensitive materials, the traditional approach is to roughen and degrease the new screen, which can ensure the quality of the screen and extend the service life of the screen. 2. Plate photosensitive materials Commonly used photosensitive materials for printing plates include diazo photosensitive agents, photosensitive films, etc. The commonly used photosensitive emulsion in screen printing is diazo type. The photosensitive film has the
The viscosity of liquid photosensitive solder mask ink is mainly controlled by the ratio of hardener to main agent and the amount of diluent added. If the amount of hardener added is not enough, it may cause an imbalance in ink characteristics. After the hardener is mixed, it will react at room temperature, and its viscosity changes as follows. Within 30 minutes: The main ink agent and hardener have not yet fully integrated, resulting in insufficient fluidity and clogging of the screen during printing. 30 minutes to 10 hours: The ink main agent and hardener have been fully integrated, and the fluidity is appropriate. After 10 hours, the reactions between the various materials of the ink itself continue to take place proactively, resulting in increased fluidity and difficulty in printing. The longer the hardener is mixed, the more complete the reaction between the resin and hardener, and as a result, the gloss of the ink also improves. To ensure even ink gloss and good printabili
1. Engineering design The arrangement of interlayer semi cured sheets should correspond; Multi layer core boards and semi cured sheets should use the same supplier's products; The area of the outer C/S surface graphics should be as close as possible, and independent grids can be used; 2. Drying the board before cutting Generally, at 150 degrees Celsius for 6-10 hours, the moisture inside the board is eliminated to further solidify the resin completely and eliminate stress inside the board; Bake the board before cutting, whether it is the inner layer or both sides! 3. Attention should be paid to the warp and weft directions of the cured sheets before laminating multi-layer boards The contraction ratio in the warp and weft directions is different. Before cutting and stacking the semi cured sheet, pay attention to distinguishing the warp and weft directions; When cutting the core board, attention should also be paid to the warp and weft directions; The general direction of the cu
The experience given by circuit board manufacturers is to choose components with large volume, multiple pins, and a major role in the circuit, such as integrated circuits, transformers, transistors, etc., as drawing reference components. Then, starting from each pin of the selected reference component, drawing can reduce errors, and error prevention is also important in the manufacturing industry. 2. If component numbers (such as VD870, R330, C466, etc.) are marked on the printed circuit board, due to the specific rules of these numbers, components with the same first Arabic numeral after the English letter belong to the same functional unit. Therefore, they should be cleverly utilized when drawing. Correctly distinguishing the components of the same functional unit is the foundation of drawing layout. There are many methods in the circuit board manufacturing methods of circuit board factories that can be applied to restore the circuit schematic. 3. If the serial number of the co
The production of printed circuit boards is mainly based on chemical processes, which consume a large amount of water and produce wastewater. From copper-clad foil base to finished printed circuit board, it undergoes multiple chemical water washes, pre-treatment and water washing through chemical electroplating, electrolytic electroplating, and surface cleaning. Clean production should save water resources and water. The chemical solution and cleaning water used are both turned into wastewater. When performing these operations, circuit board factories should first consider clean production. Clean production in circuit board factories ensures product quality, and the quality of the board and the reputation of the production enterprise are equally important. There are also printing options available: solder mask ink, marking ink, conductive ink, and plug hole ink are retained on the printed circuit board of the circuit board factory. They include photo imaging, photo dry film, corr
Ability requirements: 1. Can produce packaging for simple tones, such as DIP10, etc; 2. Master the basic operations of at least one PCB design software and be able to formulate simple rules for wiring line width and spacing; 3. Capable of arranging and wiring PCBs with 100 components and 200 networks or less in a reasonable and orderly manner; 4. Capable of manually or automatically wiring and modifying under the guidance of others or self defined rules, achieving 100% connectivity and complete DRC approval; 5. Have basic knowledge of mechanical structure and thermal design; 6. Master some basic requirements for double-sided board wiring. Job responsibilities: 1. Design and modification of simple PCBs (such as the front panel of structurally simple sound, microcontroller small system board, etc.); 2. The routing of specified parts in complex PCBs; 3. Debugging related to designing your own PCB; 4. Write relevant development and debugging logs. Factors to consider in cir
The minimum width of printed wires is related to the magnitude of the current flowing through the wires: The line width is too small, and the resistance of the printed wire is high, resulting in a large voltage drop on the line, which affects the performance of the circuit, If the line width is too wide, the wiring density will not be high, and the board area will increase. In addition to increasing costs, it is also not conducive to miniaturization If the current load is calculated at 20A/square millimeter, and the thickness of the copper foil is 0.5mm (usually so much), then the current load for a 1MM (about 40MIL) line width is 1A, Therefore, a line width of 1-2.54mm (40-100MIL) can meet the general application requirements. For the ground wire and power supply on high-power equipment boards, the line width can be appropriately increased according to the power size. On low-power digital circuits, in order to improve wiring density, a minimum line width of 0.254-1.27mm (10-15
1. Test method for uniformity of pressure: For pressure uniformity testing, there is a specialized induction paper that functions similarly to old high copy paper, with better results, but the price is very expensive. In addition, standard lead bars can be arranged for testing in the press. After completion, measuring the residual thickness of each section of the lead bars can also determine the uniformity of the press, and the values can be quantified. In addition, a more old-fashioned method is to use carbon paper to place on a piece of white paper, perform a pressing operation, and then check the imprints left on the white paper after pressing to determine which position of the press platform is not pressed enough and which position is under even pressure. 2. Temperature uniformity testing method: Using a thermocouple thermometer, make several more thermocouple wires, and then place them at nine or more points according to the position of the platform. After pressurization,
1. Generally, a large area of copper foil is designed on a circuit board for grounding purposes. Sometimes, the Vcc layer also has a large area of copper foil. When these large areas of copper foil cannot be evenly distributed on the same circuit board, it will cause uneven heat absorption and dissipation speed. Of course, the circuit board will also experience thermal expansion and contraction. If the expansion and contraction cannot be achieved simultaneously, it will cause different stresses and deformations. At this time, if the temperature of the board has reached the upper limit of Tg value, the board will begin to soften, causing permanent deformation. 2. The connection points (via) of each layer on the circuit board will limit the expansion and contraction of the board. Most current circuit boards are multi-layer boards, and there are rivet like connection points (vias) between layers. The connection points are divided into through holes, blind holes, and buried holes. The
1. The PCB circuit (bottom of the board) needs to consider the installation of electronic components by plugging them in, and after plugging in, issues such as conductivity and signal transmission performance will be considered. Therefore, the lower the impedance, the better, and the lower the resistivity, which should be less than 1 times per square centimeter; Below 10-6. 2. During the production process of PCB circuit boards, they need to go through processes such as copper deposition, electroplating tin (or chemical plating, or hot spraying tin), and connector soldering. The materials used in these processes must ensure a low electrical resistivity to ensure that the overall impedance of the circuit board meets product quality requirements and can operate normally. 3. The tin plating of PCB circuit boards is the most common problem in the entire production process, and it is a key link that affects impedance. The biggest defects of electroless tin plating are its tendency to
1. The main difference between vertical and horizontal electroplating lines in the maintenance and upkeep of the tank body lies in the different transportation methods of the circuit board, while the maintenance and upkeep methods for the tank body are essentially similar. 7 days, each water washing tank should be cleaned once. The acid washing tank should be cleaned once and its solution should be replaced; Conduct an inspection of the spray device inside the tank to check for any blockages, and promptly unblock any blockages that may occur; When cleaning the conductive supports and anode contact points on the copper plating tank and tin plating tank, a cloth can be used to wipe and sandpaper can be used to polish them; Inspect the titanium basket and tin bar basket of the copper plating tank and tin plating tank once, replace the damaged titanium basket bag and tin bar basket, and add copper balls and tin bars. After adding copper balls and tin bars in 7 days, the electroplating
For the through holes of double-sided printed circuit boards, there is no need to use copper plating to connect the two circuits. Instead, the method of filling silver paste into the through holes can also reduce the cost of double-sided printed circuit boards. The specific process diagram is shown in Figure 4 88. This method is generally used for ordinary phenolic resin paperboard with double-sided copper coating. This method first cleans the surface of ordinary phenolic resin paperboard coated with copper on both sides, and then prints corrosion-resistant patterns on both sides using screen printing method. After corrosion, a conductive pattern is formed. After removing the corrosion-resistant layer, through holes are drilled, and silver paste is filled into the holes. In order to ensure good contact between the silver paste and the conductive patterns on both sides, the silver paste should protrude through holes, and the diameter of the protruding silver paste pattern should be
From the perspective of the 5G industry chain, CITIC Securities believes that it roughly goes through the planning period, construction period, operation and maintenance period, and application period. The construction period alone includes several parts, including wireless equipment, transmission equipment, base station equipment core network equipment, engineering construction, and station site iron towers. The software and hardware of 5G networks need to be upgraded. According to CITIC Securities, the transmission equipment during the construction period mainly includes communication equipment PCBs, optical modules and devices, fiber optic cables, and transmission supporting equipment. Firstly, let's take a look at PCB, which is a printed circuit board. It refers to a substrate that connects and prints components according to pre designed forming points on the substrate. The function of a PCB is to connect electronic components according to a predetermined circuit (i.e. critic
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