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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
The direct cause of temperature rise in printed circuit boards is due to the presence of power consuming devices in the circuit. Electronic devices all have varying degrees of power consumption, and the heating intensity varies with the magnitude of power consumption. Two phenomena of temperature rise in printed circuit boards: (1) Local temperature rise or large-scale temperature rise; (2) Short term or long-term temperature rise. When analyzing PCB thermal power consumption, it is generally analyzed from the following aspects 1. Electrical power consumption (1) Analyze power consumption per unit area; (2) Analyze the distribution of power consumption on PCB circuit boards. 2. Structure of Printed Circuit Board (1) The size of the printed circuit board; (2) The material of the printed circuit board. 3. Installation method of printed circuit board (1) Installation method (such as vertical installation, horizontal installation); (2) Sealing condition and distance from t
1. Lack of planning As the saying goes, "If a person doesn't have a plan beforehand, they will find trouble and come knocking on their door." This also applies to PCB design. One of the many steps that make PCB design successful is to choose the appropriate tool. Today's PCB design engineers can find many powerful and easy-to-use electronic design automation (EDA) software suites on the market. Each model has its own unique capabilities, advantages, and limitations. Additionally, it should be noted that no software is foolproof, so issues such as mismatched component packaging are bound to occur. It is possible that there is no single tool that can meet all your needs. Nevertheless, you still need to put in effort to research in advance and strive to find the best product that best suits your needs. Some information on the internet can help you get started quickly. 2. Poor communication Although outsourcing PCB design to other manufacturers is becoming increasingly common and
1. Prevent burrs and scratches on the surface of the PCB board. 2. Plays a role in heat dissipation and cleaning the drill bit. 3. It can guide the drill bit to drill into the track of the PCB board to improve the accuracy of drilling. Aluminum sheets require a high thermal conductivity to quickly remove the heat generated during drilling and reduce the temperature of the drill bit. It is recommended to use aluminum sheets with a thickness of 0.15-0.2mm or aluminum alloy composite aluminum sheets with a thickness of 0.15-0.35mm to effectively prevent the drill bit from breaking due to poor chip removal caused by high temperatures during drilling. 3. The quality of copper-clad board material is that the fiberglass cloth of the board material is coarse, and the bonding force is not good, which can also have a significant impact on the broken drill bit. If the resin polymerization of the board is not complete, it is easy to produce a lot of adhesive residue on the hole wall, poor
Despite the cost factors mentioned above, the price of flexible assembly is decreasing and becoming closer to traditional rigid circuits. The main reason is the introduction of updated materials, improved production processes, and structural changes. The current structure enhances the thermal stability of the product, with few material mismatches. Some updated materials can produce more precise lines due to the thinner copper layer, making the components lighter and more suitable for fitting into small spaces. In the past, copper foil was adhered to a medium coated with adhesive using roller pressing technology. Nowadays, copper foil can be directly generated on the medium without using adhesive. These technologies can produce copper layers several micrometers thick, resulting in Precision lines with a width of 3m.1 or even narrower. After removing certain adhesives, flexible circuits have flame retardant properties. This can accelerate the uL certification process and further reduc
If the circuit design is relatively simple, the total volume is not large, and the space is suitable, traditional interconnection methods are mostly much cheaper. If the circuit is complex, processes many signals, or has special electrical or mechanical performance requirements, flexible circuits are a good design choice. When the size and performance of an application exceed the capacity of a rigid circuit, flexible assembly is the most economical method. A 12 mil solder pad with a 5 mil through-hole and a flexible circuit with 3 mil lines and spacing can be made on a thin film. Therefore, directly mounting chips on thin films is more reliable. Because it does not contain flame retardants that may be sources of ion drilling pollution. These films may have protective properties and cure at higher temperatures, resulting in higher glass transition temperatures. The reason why flexible materials save costs compared to rigid materials is that they eliminate the need for connectors. H
Introduction to PCB Warpage 1、 Standards and testing methods for warpage According to the American IPC-6012 (1996 edition) "Identification and Performance Specification for Rigid Printed Boards", the maximum allowable warpage and distortion for surface mounted printed boards is 0.75%, while other types of boards are allowed at 1.5%. This increases the requirement for surface mounted printed boards compared to IPC-RB-276 (1992 edition). At present, the allowable warpage for electronic assembly plants, whether it is double-layer or multi-layer boards, is 1.6mm thick, usually 0.70-0.75%. For many SMT and BGA boards, the requirement is 0.5%. Some factories are advocating to increase the warpage standard to 0.3%. The testing method for warpage follows GB4677, 5-84 or IPC-TM-6502422B. Place the board on a verified platform and insert the testing needle into the area with the maximum warpage. The warpage of the printed board can be calculated by dividing the diameter of the testing needle
What are the classifications of PCB board materials and ceramic high-frequency board series? Let's introduce them in detail below: RO3000 series: PTFE circuit materials based on ceramic filling, with models including RO3003, RO3006, RO3010, and RO3035 high-frequency laminates. RT6000 series: PTFE circuit material based on ceramic filling, designed for electronic and microwave circuits that require high dielectric constant. The models include RT6006 with a dielectric constant of 6.15 and RT6010 with a dielectric constant of 10.2. TMM series: composite materials based on ceramics, hydrocarbons, and thermosetting polymers, models: TMM3, TMM4, TMM6, TMM10, TMM10i, TMM13i. and so on
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