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On automated surface mount lines, if the circuit board is uneven, it can cause inaccurate positioning, prevent components from being inserted or attached to the holes and surface mount pads of the board, and even damage the automatic insertion machine. The circuit board with installed components bends after soldering, making it difficult to trim the component pins flat and tidy. The board cannot be installed on the chassis or socket inside the machine, so it is also very troublesome for the assembly plant to encounter board warping. At present, surface mount technology is developing towards high precision, high speed, and intelligence, which puts higher requirements on the flatness of PCB boards, which are home to various components. The IPC standard specifically states that the maximum allowable deformation for PCB boards with surface mount devices is 0.75%, while the maximum allowable deformation for PCB boards without surface mount devices is 1.5%. In fact, in order to meet the
As the name suggests, a multi-layer circuit board can only be called multi-layer if it has two or more layers, such as four, six, eight, and so on. Of course, some designs have three or five layer circuits, also known as multi-layer PCB circuit boards. A conductive wiring diagram larger than a two-layer board, with insulating substrates separating the layers. After each layer of wiring is printed, it is then pressed together to overlap each layer of wiring. Afterwards, drilling holes will be carried out to achieve conductivity between each layer of the line. The advantage of multi-layer PCB circuit boards is that the circuits can be distributed and wired within multiple layers, allowing for the design of more precise products. Or smaller products can be achieved through multi-layer boards. For example, products with larger volumes such as mobile phone circuit boards, mini projectors, and recording pens. In addition, multiple layers can increase the flexibility of the design, allowi
After the final product inspection, the PCB board can be vacuum packaged and stored for shipment. So why do PCB boards need vacuum packaging? How to store after vacuum packaging? How long is its shelf life? Why do PCB boards need vacuum packaging? Although this issue is small, it is a matter that many circuit board manufacturers attach great importance to. Because once the PCB board is not sealed properly, its surface gold deposition, tin spraying, and solder pad areas will oxidize and affect welding, which is not conducive to production. So, how should PCB boards be stored? A circuit board, unlike other products, cannot come into contact with air and water. Firstly, the vacuum of the PCB board cannot be damaged. When packing, a layer of bubble film needs to be wrapped around the edge of the box. The water absorption of the bubble film is relatively good, which plays a good role in moisture-proof. Of course, moisture-proof beads cannot be missing. Then classify and label the emis
In the process of PCB gold plating, what aspects and measures can we take to reduce the consumption of gold salts and achieve maximum product benefits? The gold layer has characteristics such as corrosion resistance, high conductivity, good weldability, low and stable contact resistance, high temperature resistance, soft texture, and wear resistance. Meanwhile, after alloying with other metals such as carbon and iron, gold has higher hardness and better wear resistance. With the rise of market gold prices, the cost of gold plating has also become a key concern for enterprises. The consumption of gold salt in electroplating gold wire mainly includes two aspects: the consumption of graphic gold layer on printed circuit board and the consumption of bath solution taken out. Excessive thickness of the gold plating layer or excessive amount of liquid carried out from the tank can lead to waste of gold salt and result in ineffective gold salt consumption costs. In addition, the current
The first thing that comes to mind when measuring the technological level of a circuit board manufacturer is the number of layers for producing and processing circuit boards. Therefore, multi-layer circuit boards have strict process requirements in the production process, and multi-layer circuit boards need to sink copper into the holes to make the through holes have copper, becoming through holes. However, during the production process, occasional inspections may reveal that there is no copper or copper is unsaturated in the hole after copper deposition. What is the reason for the lack of copper in the hole? What methods can be improved? 1. Drill dust plugs or holes that are coarse. 2. When depositing copper, there are bubbles in the solution and no copper has settled in the hole 3. There is circuit ink inside the hole, no protective layer is applied, and there is no copper in the hole after etching. 4. If the acid and alkali solution inside the hole is not cleaned thoroughly
With the rapid development of mobile phones, electronics, communication industries, and other industries, the PCB circuit board industry is also constantly growing and growing rapidly. The requirements for the number of layers, weight, precision, materials, line width, line spacing, reliability, and other aspects of circuit boards are becoming increasingly high. 1 Selection criteria for printed wire width: The minimum width of printed wire is related to the current flowing through the wire. If the wire width is too small, the resistance of the newly printed wire will be high, and the voltage drop on the wire will also be large, affecting the performance of the circuit. If the wire 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, when the thickness of the copper foil is 0.5MM (usually so much), the current
Flexibility and reliability of FPC flexible circuit boards At present, there are four types of FPC: single-sided, double-sided, multi-layer flexible board, and rigid flexible board. ① Single sided flexible board is the lowest cost printed board when it does not require high electrical performance. When wiring on one side, a single-sided flexible board should be selected. It has a layer of chemically etched conductive patterns, and the conductive pattern layer on the flexible insulation substrate surface is rolled copper foil. The insulation substrate can be polyimide, polyethylene terephthalate, aramid fiber ester, and polyvinyl chloride. ② Double sided flexible board is a conductive pattern made by etching one layer on each side of the insulating substrate film. Metallized holes connect the patterns on both sides of the insulating material to form a conductive path, in order to meet the design and functional requirements of flexibility. And the covering film can protect single an
The rapid development of industries such as mobile phones, electronics, and communication has also led to the continuous growth and expansion of the PCB circuit board industry. People have increasingly high requirements for the number of layers, weight, precision, materials, color, reliability, and other aspects of electronic components. But due to With the rapid development of industries such as mobile phones, electronics, and communication, as well as the continuous growth and expansion of the PCB circuit board industry, people have increasingly high requirements for the number of layers, weight, precision, materials, color, reliability, and other aspects of electronic components. However, due to fierce market price competition, the cost of PCB board materials is also on the rise, and more and more manufacturers are monopolizing the market with low prices in order to enhance their core competitiveness. However, behind these ultra-low prices, they are obtained by reducing materi
Introduction to PCB surface treatment tin spraying process PCB tin spraying, also known as hot air leveling, is an important process treatment in the production of PCB circuit boards. PCB circuit board tin spraying mainly includes lead-free tin spraying and lead tin spraying, which are also commonly used and widely used in circuit board manufacturers PCB tin spraying, also known as "hot air leveling", is an important process treatment in the production of PCB circuit boards. There are two main types of PCB tin spraying: lead-free tin spraying and lead tin spraying, which are also commonly used and widely used in PCB manufacturers. The quality of tin spraying directly affects the quality of subsequent customer welding, so tin spraying has become a key focus of quality control for PCB manufacturers. Below, we will introduce the characteristics and related basic knowledge of PCB tin spraying types. PCB surface treatment tin spraying characteristics: Tin spraying is the most commonly
What is the difference between positive and negative PCBs 1. The difference between positive and negative PCBs: PCB positive and negative are manufacturing processes with opposite final effects. The effect of PCB positive: The copper on the printed board is retained in areas where lines are drawn, and the copper on areas where no lines are drawn is removed. The signal layer, such as the top and bottom layers, is the positive. The effect of PCB negative film: The copper coating on the printed board is removed in areas where lines are drawn, while the copper coating is retained in areas where no lines are drawn. The Internal Planes layer (referred to as the Internal Planes layer) is used to arrange power and ground wires. The wiring or other objects placed on these layers are copper free areas, meaning that this working layer is negative. 2. What are the differences between PCB positive and negative output processes? Negative film: Generally, it is the tenting process that we ref
PCB interference is mainly divided into two types. One type comes from within the PCB, mainly due to the influence of parasitic coupling between adjacent circuits and field coupling of internal components, resulting in signal crosstalk along the transmission path. For example, capacitors on PCBs, especially those used in high-frequency situations. We can consider it as an LCR circuit, because when a capacitor actually works in a circuit, it generally produces equivalent inductance and impedance, and the capacitor has a self resonant frequency. At the self resonant frequency, the capacitor exhibits capacitance. When the frequency is higher than the self resonant frequency, the capacitance appears inductive, and the impedance increases with the increase of frequency. Another type of electromagnetic interference comes from the outside of the PCB, which is further divided into two types: radiation interference and sensitive element problems. Radiation mainly comes from harmonic sources
In terms of layout, when the circuit board size is too large, although welding is easier to control, the printed lines are longer, the impedance increases, the noise resistance decreases, and the cost increases; If it is too small, the heat dissipation will decrease, and welding will be difficult to control, making it easy for adjacent lines to interfere with each other, such as electromagnetic interference from circuit boards. Therefore, it is necessary to optimize the PCB board design: (1) Shorten the connection between high-frequency components and reduce EMI interference. (2) Components with heavy weight (such as exceeding 20g) should be fixed with brackets and then welded. (3) Heating elements should consider heat dissipation issues to prevent significant surface damage to the components Δ Defects and rework caused by T should keep the thermistor away from the heat source. (4) The arrangement of components should be as parallel as possible, which is not only aesthetically
The basic requirement for etching quality is to be able to completely remove all copper layers except below the corrosion-resistant layer, that's all. Strictly speaking, if we want to define it accurately, the etching quality must include the consistency of wire width and the degree of lateral corrosion. Due to the inherent characteristics of the current corrosive solution, it not only causes etching in the downward direction but also in both the left and right directions, so lateral corrosion is almost inevitable. The side etching problem is a frequently discussed aspect of etching parameters, defined as the ratio of side etching width to etching depth, known as the etching factor. In the printed circuit industry, its range of variation is very broad, from 1:1 to 1:5. Obviously, a small etching degree or low etching factor is the most satisfactory. The structure of the etching equipment and the different components of the etching solution will have an impact on the etching facto
It should be noted that there are two layers of copper on the board during etching. In the outer etching process, only one layer of copper must be completely etched off, while the rest will form the final required circuit. This type of graphic electroplating is characterized by the copper plating layer only existing below the lead tin corrosion-resistant layer. Another process method is to plating copper on the entire board, with only tin or lead tin corrosion-resistant layer on the outer part of the photosensitive film. This process is called "full plate copper plating process". Compared with graphic electroplating, the biggest drawback of full plate copper plating is that copper must be plated twice on all parts of the board, and they must also be corroded off during etching. Therefore, when the wire width is very fine, a series of problems will occur. At the same time, side corrosion will seriously affect the uniformity of the lines. In the processing technology of the outer c
Activation and copper deposition are key processes in the process of pore metallization in chemical plating. Although qualitative and quantitative analysis of ion palladium and reducing solution can reflect the activation and reduction performance, their reliability is not comparable to that of glass cloth tests. The most stringent conditions for copper deposition on glass cloth can best demonstrate the performance of activation, reduction, and copper deposition solution. The current introduction is as follows: (1) Material: Deslur the glass cloth in a 10% sodium hydroxide solution. And cut it into 50 x 50 (mm), remove some glass fibers from the ends around it, and let the glass fibers scatter. (2) Test steps: A. Treat the sample according to the copper deposition process procedure; B. Put it into the copper plating solution, and after 10 seconds, the end of the glass cloth should be completely coated with copper, appearing black or dark brown. After 2 minutes, all should be coat
Before through-hole plating, the copper foil is subjected to micro etching treatment to roughen the microstructure and increase the adhesion with the deposited copper layer. To ensure the stability of the etching solution and the uniformity of copper foil etching, it is necessary to measure the etching rate to ensure it is within the specified range of the process. (1) Material: 0.3mm copper foil plate, degreased, brushed, and cut into 100 x 100 (mm); (2) Measurement procedure: A. The sample is corroded in hydrogen peroxide (80-100 g/L) and sulfuric acid (160-210 g/L) at a temperature of 30 ℃ for 2 minutes, and then cleaned with deionized water; B. Bake at 120-140 ℃ for 1 hour, weigh W2 (g) at constant weight, and weigh W1 (g) at constant weight before corrosion. (3) Etching rate calculation rate=(W1-W2) 104/2 x 8.933T( μ M/min) In the formula: s - sample area (cm2) T - etching time (min) (4) Judgment: 1-2 μ The corrosion rate of m/min is appropriate. (Corrosion of copper 270-
What are the key points in PCB design? 1. Select PCB board The selection of PCB boards must strike a balance between meeting design requirements and achieving mass production and cost. The design requirements include two parts: electrical and mechanical. This material issue is usually important when designing very high-speed PCB boards (frequencies greater than GHz). For example, the commonly used FR-4 material may not be suitable as its dielectric loss at several GHz frequencies can have a significant impact on signal attenuation. In terms of electrical performance, attention should be paid to whether the dielectric constant and dielectric loss are used together at the designed frequency. 2. Avoiding high-frequency interference The basic idea to avoid high-frequency interference is to minimize the interference of high-frequency signal electromagnetic fields, also known as crosstalk. You can widen the distance between the high-speed signal and the analog signal, or add ground gua
In the electroplating process, it is common to have poor adhesion when spraying paint on the coating, which is due to the presence of oil stains on the surface after electroplating. However, during the electroplating of parts, pinholes often occur after plating. Today, we will talk about pinholes caused by improper pre-treatment and the corresponding solutions. Frequently asked questions: (1) Parts that are not thoroughly degreased or stored improperly during machining may have dust falling on the surface. If left for a long time, the dust and grease may mix together, making it difficult to remove them completely, resulting in inconspicuous small oil spots. During plating, bubbles may remain on them, forming pinholes. (2) When polishing parts, abrasives, polishing paste, etc. are embedded in micro pits on the surface, which are difficult to clean and cannot deposit the coating, resulting in pinholes. (3) Incomplete or prolonged pickling of components may result in corrosion, wi
PCB board surface treatment PCB board surface treatment: oxidation resistance, tin spraying, lead-free tin spraying, gold sinking, tin sinking, silver sinking, hard gold plating, full board gold plating, gold finger, nickel palladium OSP: low cost, good solderability, strict storage conditions, short time, environmentally friendly process, good welding, and flatness. Tin spraying: Tin spraying boards are generally multi-layer (4-46 layers) high-precision PCB templates, which have been used by many large domestic communication, computer, medical equipment, aerospace enterprises and research units. The connecting finger is a connecting component between the memory module and the memory slot, and all signals are transmitted through the connecting finger. The golden finger is composed of numerous golden conductive contacts, and is called the "golden finger" because its surface is gold-plated and the conductive contacts are arranged like fingers. The golden finger is actually coated wi
As the integration level of ICs increases, the number of IC pins also increases. However, the vertical tin spraying process is difficult to blow flat the fine solder pads, which brings difficulty to SMT mounting; In addition, the shelf life of tin spray boards is very short. And the gold-plated plate precisely solves these problems: 1. For surface mount technology, especially for 0603 and 0402 ultra small surface mount, the flatness of the solder pads directly affects the quality of the solder paste printing process and has a decisive impact on the quality of subsequent reflow soldering. Therefore, whole board gold plating is often seen in high-density and ultra small surface mount processes. 2. In the trial production stage, the influence of factors such as component procurement is often not that the board is soldered immediately upon arrival, but that it often has to wait for several weeks or even months before use. The shelf life of gold-plated boards is many times longer than
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