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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. Drilling parameters: The setting of drilling parameters is crucial. If the drilling speed is too fast, the drilling nozzle will break due to excessive force, and if the drilling speed is too slow, it will reduce production efficiency. Due to differences in the thickness, copper thickness, and material structure of PCB boards produced by various board manufacturers, PCBs need to be set according to specific circumstances. Select the most suitable drilling parameters through calculation and testing. Generally, for a 0.3mm drill bit, the cutting speed should be between 1.5-1.7m/min, and the drilling depth should be controlled between 0.5-0.8. 2. The cushion plate used for drilling aluminum sheets requires a moderate hardness, uniform thickness, flatness, and a thickness difference of no more than 0.076mm. If the distribution of the cushion plate's softness and hardness is irregular, it is easy to get stuck in the drilling nozzle. If the cushion plate is uneven, it will cause the p
At present, there are four types of flexible circuits: single-sided, double-sided, multi-layer flexible boards, and rigid flexible boards. 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 and double-sided wires and indicate the posi
At present, 5G is booming, and with the arrival of the 5G era, PCB, as the mother of the electronic industry and the carrier of all components, occupies the largest proportion and benefits the PCB industry in this chain. The development of 5G cannot do without the construction of large-scale data centers, which will inevitably increase the number of servers. The development of servers cannot do without PCBs. Due to the huge traffic carried by data centers and the high requirements for transmission speed, the requirements for the number of layers and materials of PCBs will also become higher. In this case, the demand for high-end communication boards will be greatly increased. With the continuous advancement of 5G construction, due to the high-speed and high-frequency characteristics of 5G, the value of communication boards for a single base station will also be greatly increased, and the demand for communication boards in 5G base station construction will be further stimulated. F
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 the multi-layer board: 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 th
1. Hot air leveling (tin spraying) Hot air leveling, also known as hot air solder leveling (commonly known as tin spraying), is a process of coating the surface of a PCB with molten tin (lead) solder and flattening it with heated compressed air, forming a coating layer that is not only resistant to copper oxidation but also provides good solderability. Hot air leveling forms copper tin intermetallic compounds at the junction of solder and copper. PCB should sink into the melted solder during hot air leveling; The wind knife blows out the liquid solder before it solidifies; The wind knife can minimize the crescent shape of the solder on the copper surface and prevent solder bridging. 2. Organic Solderability Protector (OSP) OSP is a process for surface treatment of copper foil on printed circuit boards (PCBs) that complies with RoHS instructions. OSP is the abbreviation for Organic Solderability Preservatives, which is translated as organic solder mask, also known as copper prote
1. Issues related to substrate processing: Especially for some thinner substrates (usually below 0.8mm), due to poor substrate rigidity, it is not suitable to use a brush machine to brush the board. This may not effectively remove the protective layer specially treated to prevent oxidation of the copper foil on the surface of the substrate during production and processing. Although this layer is thin and easy to remove by brushing, chemical treatment poses significant difficulties. Therefore, it is important to pay attention to control during production and processing to avoid poor bonding between the substrate copper foil and chemical copper, which may cause foaming on the surface of the substrate; When blackening is carried out on thin inner layers, there may also be problems such as poor blackening and browning, uneven color, and poor local blackening and browning. 2. The phenomenon of poor surface treatment caused by oil stains or other liquids contaminated with dust during
If you want to produce circuit boards that do not contain halogen elements, you need to start with the raw materials. According to the JPCA-ES-01-2003 standard, copper clad boards with chlorine (C1) and bromine (Br) content less than 0.09% Wt (weight ratio) are defined as halogen-free copper clad boards. (Meanwhile, the total amount of CI+Br is ≤ 0.15% [1500PPM]). So why ban brine? Halogens refer to halogen elements in the periodic table of chemical elements, including fluorine (F), chlorine (CL), bromine (Br), and iodine (1). At present, flame retardant substrates such as FR4 and CEM-3 are mostly brominated epoxy resins as flame retardants. In brominated epoxy resin, tetrabromobisphenol A, polybrominated biphenyls, polybrominated biphenyl ethers, and polybrominated diphenyl ethers are the main blocking fuels for copper clad laminates, with low cost and compatibility with epoxy resin. However, research by relevant institutions has shown that flame retardant materials containing ha
1. The resistance generated by alternating current on components is related to capacitance and inductance. When an electronic signal waveform is transmitted in a conductor, the resistance it experiences is called impedance. 2. Resistance is the resistance generated by direct current on components, which is related to voltage, resistivity, and current. Application of characteristic impedance 1. The electrical performance provided by printed circuit boards for high-speed signal transmission and high-frequency circuits must be able to prevent reflection during signal transmission, maintain signal integrity, reduce transmission losses, and play a matching role. Only in this way can complete, reliable, accurate, worry free, and noise free transmission signals be obtained. 2. The size of impedance cannot be simply understood as better or better, the key is matching. Control parameters of characteristic impedance
1. Bubbles There are bubbles generated between the lines or on the side of a single line on an FPC printed board after development. Main reasons: The formation of bubbles between two or more lines is mainly due to the narrow spacing between the lines and the high height of the lines. During screen printing, the solder mask cannot be printed on the substrate, resulting in the presence of air or moisture between the solder mask and the substrate. During curing and exposure, the gas expands due to heating, causing a single line to be mainly caused by the high height of the line. When the scraper contacts the line, the line is too high, and the angle between the scraper and the line increases, making it impossible for the solder mask to be printed on the root of the line. This causes gas to exist between the side of the line root and the solder mask layer, and after heating, bubbles are generated. The solution is to visually inspect whether the solder mask is completely printed on the
1. The effect of reducing temperature on the stress of PCB boards Since temperature is the main source of stress on the board, reducing the temperature of the reflow furnace or slowing down the heating and cooling rate of the board in the reflow furnace can greatly reduce the occurrence of bending and warping of the board. However, there may be other side effects, such as solder short circuits. 2. Using high Tg boards Tg is the glass transition temperature, which is the temperature at which a material transitions from a glass state to a rubber state. The lower the Tg value of a material, the faster its board begins to soften after entering the reflow furnace, and the longer it takes to become a soft rubber state, the more severe the deformation of the board. Using a higher Tg board can increase its ability to withstand stress and deformation, but the cost of the material is relatively high. 3. Increase the thickness of the circuit board Many electronic products, in order to ac
Poor solderability of circuit board holes will result in virtual soldering defects, affecting the parameters of components in the circuit, leading to unstable conduction of multi-layer board components and inner wires, and causing the entire circuit function to fail. The so-called weldability refers to the property of the metal surface being wetted by molten solder, that is, the formation of a relatively uniform and continuous smooth attached film on the metal surface where the solder is located. The main factors affecting the solderability of printed circuit boards are: (1) the composition of the solder and the properties of the soldered material. Solder is an important component of the welding chemical treatment process, which is composed of chemical materials containing flux. The commonly used low melting point eutectic metals are Sn-Pb or Sn-Pb-Ag. The impurity content should be controlled in a certain proportion to prevent the oxide produced by impurities from being dissolve
1. Problem: Decreased etching rate in printed circuits Reason: Caused by improper control of process parameters Solution: Inspect and adjust process parameters such as temperature, spray pressure, solution density, pH value, and ammonium chloride content to the specified values according to process requirements. 2. Problem: Deposition of etching solution in printed circuits Reason: (1) The ammonia content is too low (2) Excessive water dilution (3) The specific gravity of the solution is too high Solution: (1) Adjust the pH value to reach the process specified value or appropriately reduce the exhaust volume. (2) Strictly follow the process requirements or reduce the exhaust volume appropriately during adjustment. (3) According to the process requirements, a portion of the solution with high specific gravity is discharged and analyzed, and then an aqueous solution of ammonium chloride and ammonia is added to adjust the specific gravity of the etching solution to the al
There are certain technical requirements for the rate of copper deposition when using a chemical copper plating solution. If the speed is too slow, it may cause voids or pinholes in the hole wall; If the copper deposition rate is too fast, it will result in rough coating. Therefore, scientific determination of copper deposition rate is one of the means to control the quality of copper deposition. Taking the example of the chemical plating of thin copper provided by Xianling, briefly introduce the method for measuring the copper deposition rate: (1) Material: Using epoxy substrate after copper etching, with a size of 100 x 100 (mm). (2) Measurement steps: A. Bake the sample at 120-140 ℃ for 1 hour, and then weigh W1 (g) using an analytical balance; B. Corrosion in a mixture of 350-370 grams/liter of chromic anhydride and 208-228 milliliters/liter of sulfuric acid (at a temperature of 65 ℃) for 10 minutes, then rinse with clean water; C. Treat the waste liquid from chromium removal
In general, the distribution of copper foil on PCB circuit boards is very complex and difficult to accurately model. Therefore, when modeling, it is necessary to simplify the shape of the wiring and make ANSYS models as close as possible to the actual circuit board. The electronic components on the circuit board can also be simulated using simplified modeling, such as MOS transistors, integrated circuit blocks, etc. Thermal analysis Thermal analysis in SMT processing can assist designers in determining the electrical performance of components on PCB circuit boards, helping them determine whether components or circuit boards will burn out due to high temperatures. Simple thermal analysis only calculates the average temperature of the circuit board, while complex ones require establishing transient models for electronic devices containing multiple circuit boards. The accuracy of thermal analysis ultimately depends on the accuracy of the component power consumption provided by the c
To obtain the accurate cause or mechanism of PCB failure or defect, basic principles and analysis processes must be followed. Otherwise, valuable failure information may be missed, resulting in the inability to continue the analysis or the possibility of obtaining incorrect conclusions. The general basic process is to first determine the failure location and mode based on the failure phenomenon through information collection, functional testing, electrical performance testing, and simple visual inspection, that is, failure localization or fault localization. For simple PCBs or PCBAs, it is easy to determine the location of failure. However, for more complex BGA or MCM packaged devices or substrates, defects are not easy to observe through a microscope and cannot be determined at the moment. In this case, other means need to be used to determine. Next, it is necessary to analyze the failure mechanism, using various physical and chemical methods to analyze the mechanisms that cause
With the development of electronic products towards high density and precision, the same requirements have been put forward for circuit boards. The most effective way to increase PCB density is to reduce the number of through holes and precisely set blind holes and buried holes to achieve this. 1. Definition of blind holes a: Compared to through holes, through holes refer to holes that are drilled through each layer, while blind holes are non drilled through holes. (Illustrated, eight layer board examples: through hole, blind hole, buried hole) b: blind hole subdivision: BLIND HOLE, buried hole Buried HOLE (outer layer not visible); c: Distinguish from the production process: blind holes are drilled before pressing, while through holes are drilled after pressing. 2. Production method A: Diamond belt: (1) : Select reference point: Select a through hole (i.e. a hole in the first drilling strip) as the unit reference hole. (2) Each blind hole drill belt needs to select a hole an
OSP is the abbreviation for Organic Solderability Preservatives, also known as copper protector. Simply put, OSP is a chemical method that grows a layer of organic film on a clean bare copper surface. This film has oxidation resistance, heat resistance, impact resistance, and moisture resistance, used to protect the copper surface of circuit boards from oxidation or vulcanization in normal environments; But in the subsequent welding high temperature, this protective film must be easily removed by the flux quickly, so that the exposed clean copper surface can immediately combine with the molten solder to form a solid solder joint in a very short time. 1. Process flow: degreasing → water washing → micro etching → water washing → acid washing → pure water washing → OSP → pure water washing → drying. 2. Principle: A layer of organic film is formed on the copper surface of the circuit board, firmly protecting the fresh copper surface and preventing oxidation and pollution even at high
To solve the above problems of gold-plated boards, PCBs using gold-plated boards mainly have the following characteristics: 1. Due to the different crystal structures formed by gold deposition and gold plating, gold deposition will appear more yellow than gold plating, resulting in better customer satisfaction. 2. Due to the different crystal structures formed by sinking gold and plating gold, sinking gold is easier to weld than plating gold, and will not cause welding defects, leading to customer complaints. 3. Due to the fact that only nickel gold is present on the solder pad of the sinking gold plate, the signal transmission in the skin effect is in the copper layer and will not affect the signal. 4. Due to the denser crystal structure of deposited gold compared to gold plating, it is less prone to oxidation. 5. Due to the fact that only nickel gold is present on the solder pad of the sinking gold plate, it will not produce gold wire and cause slight shortening.
1. Annual maintenance knowledge: 1. Clean the dust on the circuit board. 2. The electrolytic capacitor capacity in the circuit board is randomly checked, if the capacity of the electrolytic capacitor is found to be less than 20% of the nominal capacity, it should be replaced, and the general life of the electrolytic capacitor should be replaced for about ten years to ensure the working performance of the pcb. 3. For high-power devices coated with heat dissipation silicone grease, check whether the heat dissipation silicone grease is dry and solid. For dry and solid devices, remove the dry and solid heat dissipation silicone grease and apply new heat dissipation silicone grease to prevent the high-power devices in the circuit board from burning out due to poor heat dissipation. 2, seasonal maintenance: 1. Clean the dust on the circuit board every quarter, use the circuit board special cleaning solution for cleaning, after cleaning the dust above, dry the circuit board with a ha
First, the different materials used in flexible circuit boards cause the diversity of prices Taking ordinary double panels as an example, the board material is generally PET, PI, etc., the board thickness ranges from 0.0125mm to 0.10mm, and the copper thickness ranges from 0.0125mm to 0.10mm. Oz to 3 Oz, all of which creates a huge price difference in sheet metal alone; The different brands of materials also have a certain price difference, so the different materials cause the diversity of prices. Second, the different production processes used in flexible circuit boards cause the diversity of prices Different production processes result in different costs. Such as gold-plated plate and tinned plate, the accuracy of the production shape, the use of silk screen lines and dry film lines will form different costs, leading to the diversity of prices. Third, the price diversity caused by the different difficulty of the flexible circuit board itself Even if the material is the same
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