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Have you noticed that now more and more of our lighting is using led lighting.What is LED? Compared to the traditional light bulbs, LEDs have lower power consumption, longer lifetime and higher energy efficiency. In the PCB industry,when we say LED PCB, it refers to the pcb used for LED lighting, if you are looking for a suitable LED PCB for your lighting system, this article may bring you something. WHAT ARE LEDS COMPOSED OF?LED is an initial light-emitting diode that produces light when an electric current passes through. LEDs typically have negative and positive electrodes, which generate light in the visible light region.The LEDS are glued to the PCB by soldering process and have electrical connections for lighting.Since light-emitting diodes dissipate a lot of heat when they are in use, when you are designing LED, the metal core is usually the best choice for LED PCB, it is because that it dissipates heat more faster. Among them, the metal material aluminum is the most widely used
(1) Characteristic impedance In electronic information products such as computers and wireless communication, the energy transmitted in the circuit of a PCB is a square wave signal (pulse) composed of voltage and time, and the resistance it encounters is called characteristic impedance. (2) Differential impedance Two identical signal waveforms with opposite input polarity at the driving end are transmitted by two differential lines, and these two differential signals are subtracted at the receiving end. The differential impedance is the impedance Zdiff between two lines. (3) Odd mode impedance The impedance of one line to ground in the two lines is consistent. (4) Even mode impedance The impedance Zcom of two identical signal waveforms with the same input polarity at the driving end when connecting the two wires together. (5) Common mode impedance The impedance Zoe of one line to ground in the two lines is consistent, usually greater than the odd mode impedance.
1) Single panel process flow Cutting and grinding → drilling → outer layer graphics → (full plate gold plating) → etching → inspection → silk screen welding resistance → (hot air leveling) → silk screen characters → contour processing → testing → inspection 2) Process flow of double-sided tin spraying board Cutting and grinding → drilling → copper sinking and thickening → outer layer graphics → tin plating, etching and tin removal → secondary drilling → inspection → silk screen resistance welding → gold-plated plug → hot air leveling → silk screen characters → external processing → testing → inspection 3) Process flow of nickel gold plating on double-sided boards Cutting and grinding → drilling → copper sinking and thickening → outer layer graphics → nickel plating, gold film removal and etching → secondary drilling → inspection → silk screen resistance welding → silk screen characters → external processing → testing → inspection 4) Process flow of multi-layer tin spraying bo
The names of circuit boards include: ceramic circuit boards, alumina ceramic circuit boards, aluminum nitride ceramic circuit boards, circuit boards, PCB boards, aluminum substrates, high-frequency boards, thick copper plates, impedance boards, PCBs, ultra-thin circuit boards, ultra-thin circuit boards, printed (copper etching technology) circuit boards, etc. Circuit boards make circuits miniaturized and intuitive, playing an important role in the mass production of fixed circuits and optimizing the layout of electrical appliances. A circuit board can be called a printed circuit board or a printed circuit board, with the English name "Printed Circuit Board" PCB (Flexible Printed Circuit Board) FPC circuit board (FPC circuit board, also known as flexible circuit board) is a highly reliable and excellent flexible printed circuit board made of polyimide or polyester film as the substrate. It has the characteristics of high wiring density, light weight, thin thickness, and good bending p
The circuit processing of multi-layer PCBs is no different from that of single-layer and double-layer PCBs, but the biggest difference lies in the through hole process. The circuits are all etched, and the via holes are drilled and then plated with copper. Everyone involved in hardware development understands these, so we won't go into detail. Multilayer circuit boards typically include through hole boards, first order boards, second order boards, and second order stacked hole boards. Higher level boards such as third-order boards and arbitrary layer interconnection boards are rarely used in daily life, and their prices are quite expensive. We won't discuss them much for now. In general, 8-bit microcontroller products use 2-layer through-hole boards; Intelligent hardware at the 32-bit microcontroller level, using 4-6-layer through-hole boards; Intelligent hardware at the Linux and Android levels, using 6-layer through holes to 8-layer first-order HDI boards; Compact products lik
1. The meaning of the solder mask layer is to open a window on the green oil of the entire solder mask, in order to allow welding! 2. By default, areas without solder mask must be coated with green oil! 3. Paste mask layer for SMD packaging! SMT encapsulation uses: toplayer layer, topsolver layer, toppaste layer, and the toplayer is the same size as the toppaste layer, but the topsolver is one circle larger than them. DIP encapsulation only uses the top layer and multi layer layers (after some decomposition, I found that the multi layer layer is actually the top layer, bottomlayer, top layer, and bottomlayer layers with overlapping sizes), and the top layer/bottomlayer is one circle larger than the top layer/bottomlayer. Question: Is the statement 'tin or gold plating only occurs when the copper layer corresponding to the solder layer has copper' correct? This sentence is from a person who works in a PCB factory. His meaning is: to make the effect of tin plating on the part pain
Protel 99 SE provides 16 mechanical layers, which are generally used to set the overall dimensions, data markers, alignment markers, assembly instructions, and other mechanical information of circuit boards. These information may vary depending on the requirements of the design company or PCB manufacturer. Executing the menu command Design | MechanicalLayer can set more mechanical layers for the circuit board. In addition, the mechanical layer can be attached to other layers to output the display together. 4 Solder mask layer Apply a layer of paint, such as solder mask, to various areas outside the solder pad to prevent tin from being applied to these areas. The solder mask layer is used to match the solder pad during the design process and is automatically generated. Protel 99 SE provides two solder mask layers: Top Solder and Bottom Solder. 5 Paste mask layer Its function is similar to that of the solder mask layer, except for the corresponding bonding pads of surface mounted
The volume of electronic products is becoming increasingly thin and short, and directly stacking holes on through blind holes is a design method to achieve high-density interconnection. To do a good job of stacking holes, the first step is to ensure the flatness of the hole bottom. There are several production methods, and the electroplating hole filling process is one of the representative ones. Next, let the PCB engineer teach you about the PCB electroplating hole filling process. 1. Advantages of electroplated hole filling: (1) Beneficial for designing stacked holes and holes on the disc; (2) Improving electrical performance helps with high-frequency design; (3) Helps to dissipate heat; (4) Plug holes and electrical interconnections are completed in one step; (5) The blind hole is filled with electroplated copper, which has higher reliability and better conductivity than conductive adhesive. 2. Physical impact parameters The physical parameters that need to be studied in
On PCBs, nickel is used as a substrate coating for precious and base metals. The deposition layer of low stress nickel on PCB is usually prepared using modified Watt nickel plating solution and some amino sulfonic acid nickel plating solution with stress reducing additives. What are the common problems encountered when using PCB nickel plating solution, as analyzed by CITIC Huawei? 1、 Temperature - Different nickel processes use different plating bath temperatures. In nickel plating solutions with higher temperatures, the obtained nickel coating has low internal stress and good ductility. The general operating temperature is maintained at 55-60 degrees Celsius. If the temperature is too high, nickel salt hydrolysis will occur, causing pinholes in the coating and reducing cathodic polarization. 2、 PH value - The pH value of nickel plating electrolyte has a significant impact on the performance of the coating and electrolyte. The pH value of PCB nickel plating electrolyte is genera
The volume of electronic products is becoming increasingly thin and short, and directly stacking holes on through blind holes is a design method to achieve high-density interconnection. To achieve good hole stacking, the first step is to ensure the flatness of the hole bottom. There are several typical methods for making flat hole surfaces, and electroplating hole filling process is one of the representative ones. The electroplating hole filling process can not only reduce the necessity of additional process development, but also be compatible with current process equipment, which is conducive to achieving good reliability. So, what factors affect the PCB electroplating hole filling process? In PCB sampling, the influence of substrate on electroplating hole filling cannot be ignored, generally including factors such as dielectric layer material, hole shape, thickness to diameter ratio, and chemical copper coating. (1) Medium layer material. The material of the dielectric layer ha
In PCB sampling, nickel is used as a substrate coating for precious and base metals. For some surfaces with heavy load wear, using nickel as the gold substrate coating can greatly improve wear resistance. When used as a barrier layer, nickel can effectively prevent the diffusion between copper and other metals. Next, CITIC Huawei will explain the causes and solutions of PCB nickel plating process faults: 1、 Ma Keng: Ma Keng is the result of organic pollution; If the stirring is poor, bubbles cannot be expelled and pits will form. Large pits usually indicate oil contamination, and wetting agents can be used to reduce their impact. Small pits are called pinholes, which can be caused by poor treatment, metal impurities, low boric acid content, and low plating temperature. Bath maintenance and process control are key, and anti pinhole agents should be used as process stabilizers to supplement. 2、 Roughness and burrs: Roughness indicates that the solution is dirty, which can be correc
When designing high altitude circuit boards, multi-layer circuit boards are usually used instead of single-layer and double-layer circuit boards. Why is this? Today brings you the reason for using multi-layer boards for high-speed circuit boards! Let's take a look together! Multi layer boards have many characteristics that are not found in single or double layer boards, and it is precisely because of these characteristics that high-speed circuit board designs use multi layer boards instead of other circuit boards. The following is a summary of the characteristics of multi-layer boards! 1. The power supply is very stable; 2. The circuit impedance is significantly reduced; 3. The wiring length is significantly shortened. In addition, from a cost perspective, although the cost of multi-layer circuit boards is higher than that of single-layer circuit boards, the cost difference between multi-layer circuit boards and single-layer circuit boards is not as high as expected when consider
High frequency board refers to a special circuit board with high electromagnetic frequency. Generally speaking, high frequency can be defined as a frequency above 1GHz. The application range of high-frequency circuit boards is very wide, and there are strict requirements in design and manufacturing. So, what are the specific requirements for the production of high-frequency PCB circuit boards? 1. The corner of the transmission line should adopt a 45 ° angle to reduce return loss; 2. The use of high-performance dielectric circuit boards with strictly controlled dielectric constant values according to the number of layers is conducive to effective simulation calculation of the electromagnetic field between insulation materials and adjacent wiring. 3. Produce according to the design specifications for high-precision etching of circuit boards. The total error of the specified line width is+/-0.0007 inches, and overall management of the wiring (wire) geometry and coating surface is c
The size of HDI is limited by the capacity of electronic processing production line equipment, therefore, appropriate HDI size should be considered in product system design. (1) The maximum HDI size that SMT devices can mount comes from the standard size of HDI sheets, most of which are 20 " × 24 ″, i.e. 508mm × 610mm (rail width) (2) The recommended size is a relatively suitable size for each equipment on the SMT production line, which is conducive to maximizing the production efficiency of each equipment and eliminating equipment bottlenecks. (3) For small-sized HDI, it should be designed as a combination to improve the production efficiency of the entire production line. Design Requirements (1) In general, the maximum size of HDI should be limited to 460mm × Within the range of 610mm. (2) The recommended size range is (200-250) mm × (250~350) mm, the aspect ratio should be
What is HDI (High Density Interconnects) wiring? HDI (High Density Interconnects) wiring refers to the use of the latest design strategies and manufacturing technologies to achieve more dense designs without affecting circuit functionality. In other words, HDI involves the use of multiple wiring layers, smaller wiring, vias, solder pads, and thinner substrates to install complex and usually high-speed circuits within previously impossible footprint areas. With the development of manufacturing technology, HDI wiring has begun to be seen in many designs, such as motherboards, graphics controllers, smartphones, and other space limited devices. If implemented properly, HDI wiring can not only greatly reduce design space, but also reduce EMI issues on PCBs. Reducing costs is an important goal for the company, and HDI cabling can precisely achieve this. It is important to understand that HDI wiring and micro vias are more complex than typical multi-layer wiring strategies. We may have de
1、 Raw materials The raw materials for PCB sinking gold plates mainly include substrates, electroplating solutions, and chemicals. Among them, the substrate is the main component of the PCB gold plate, and the material and quality of the substrate directly affect the quality of the PCB gold plate. If the material of the substrate is impure or of poor quality, it is easy to cause carbon elements in the PCB gold plate to exceed the standard. 2、 Production process The production process of PCB sinking plates includes multiple processes such as chemical gold plating, electroplated gold plating, and nickel plating. In these links, if the operation is improper or the process is not perfect, it can lead to excessive carbon content in PCB gold plating plates. For example, in the chemical gold plating process, if the temperature, pH value, concentration and other parameters of the plating solution are not suitable, it can lead to excessive carbon content. 3、 Equipment and facilities Th
1、 Design phase 1. Preliminary design. The first step in PCB design is to determine the circuit diagram, select components and connect circuits based on the functional requirements of the product. 2. Perform PCB layout. Layout design is the first step after completing circuit design, which requires determining the approximate size and shape of the PCB board, as well as the approximate positions of various components on the board. 3. Wiring design. Designers need to design the connection method and path of the circuit at each layer of the PCB, which is called wiring design. 2、 Material preparation stage 1. Select the substrate. Before starting the production of PCB multilayer boards, it is necessary to choose a suitable substrate, usually fiberglass board. 2. Make copper foil. Copper foil is the most important conductive material in PCB, and thickness selection and production should be based on the design requirements of the PCB. 3. Produce photoresist film. Photoetching film
1、 Material selection The production of high-frequency and high-speed printed circuit boards requires the selection of materials with good electrical properties. However, there are many types of materials on the market, and how to choose the appropriate materials has become a challenge. Firstly, it is necessary to consider the dielectric constant and loss factor of the material to ensure the stability and low loss of signal transmission. Secondly, it is also necessary to consider the thermal expansion coefficient and thermal conductivity of the material to avoid size changes and heat accumulation caused by temperature changes. In addition, the machinability and cost of materials also need to be considered. 2、 Design specifications The design of high-frequency and high-speed printed circuit boards needs to comply with certain standards. Firstly, it is necessary to layout the circuit reasonably to reduce the transmission path and interference of the signal. Secondly, it is necessa
1、 Design considerations When designing multi-layer circuit boards, the following points need to be noted: 1. Determine the number of circuit board layers and interlayer connection methods, reasonably plan the layout of signal and power layers, and avoid signal interference and power noise. 2. Reasonably arrange the size and layout of the circuit board to ensure its manufacturability and assemblability. 3. Choose appropriate line width and spacing to avoid signal crosstalk and current overload. Multilayer circuit board 2、 Material selection considerations When selecting materials for multi-layer circuit boards, the following points need to be noted: 1. Choose high-quality substrate materials, such as FR-4 or high-frequency materials, to ensure the stability and reliability of the circuit board. 2. Choose the appropriate thickness of copper foil, based on current and signal requirements, to avoid overload and signal distortion. 3. Select appropriate interlayer dielectric m
1. Process flow The main process flow of testing and quality inspection includes AOI testing, X-ray testing, antioxidant treatment, and aging treatment, each step of which needs to be strictly executed according to the process. Due to the crucial importance of testing and quality inspection in ensuring product quality and performance, it is necessary to pay more attention to the control of technical points. 2. Technical points In the process of testing and quality inspection, there are several technical points that need special attention: (1) Requirements for AOI testing. In the process of AOI detection, attention should be paid to the hardware and software requirements to ensure the effectiveness and accuracy of the detection. (2) Technical requirements for X-ray detection. In the process of X-ray detection, attention should be paid to the parameters and equipment requirements to ensure the effectiveness and accuracy of the detection. (3) Requirements for antioxidant treatme
Firstly, we need to consider the specific application scenarios and requirements of PCBs. If a PCB is to be used for high-frequency circuits or high-speed signal transmission, a thinner ink thickness may be more suitable as it can reduce signal transmission loss and reflection. Additionally, if the PCB is to be used in high-temperature environments or circuits with higher power, a thicker ink thickness may be more suitable as it can provide better insulation and heat dissipation performance. Secondly, we also need to consider PCB manufacturing process and cost factors. A thinner ink thickness may require higher manufacturing accuracy and more complex process flow, which may increase manufacturing costs. A thicker ink thickness may be easier to achieve, but it may increase the weight and size of the PCB. Therefore, when selecting ink thickness, it is necessary to comprehensively consider manufacturing process and cost factors. Finally, we also need to consider the reliability and
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