+86 755 2794 4155 
sales@knownpcb.com
PCB gold plate oxidation The oxidation of the submerged gold plate is the contamination of the gold surface by impurities, and the impurity attached to the gold surface changes color after oxidation, which leads to the gold surface oxidation that we often say. In fact, the gold surface oxidation statement is not accurate, gold is an inert metal, under normal conditions will not occur oxidation, and impurities attached to the gold surface such as copper ions, nickel ions, microorganisms in the normal environment is easy to oxidize to form gold surface oxides. Through observation, it is found that the oxidation of gold plate has the following characteristics: 1, improper operation causes pollutants to adhere to the gold surface, such as: with unclean gloves, finger cover contact with gold surface, gold plate and unclean table, pad contact pollution; Such oxidation area is large, may appear on multiple adjacent pads at the same time, and the appearance color is lighter and easier to
Thermal stability of PCB materials The content of nitrogen and phosphorus in halogen-free plate is higher than that of common halogen-based material, so the monomer molecular weight and Tg value are increased. In the case of heat, the molecular movement capacity will be lower than that of conventional epoxy resins, so the coefficient of thermal expansion of halogen-free materials is relatively small. Compared with halogen-free plate, halogen-free plate has more advantages, and halogen-free plate replaces halogen-free plate is also the trend of The Times. Five, the production of halogen-free PCB experience 1 ply Laminating parameters may vary from company to company. Take the above mentioned Sheng benefit substrate and PP multi-layer board, in order to ensure the full flow of resin, so that the binding force is good, the requirements of low plate heating rate (1.0-1.5℃ / min) and multi-stage pressure coordination, and in the high temperature stage requires a longer time, 180℃ to m
PCB halogen-free plate characteristics 1 Insulation of the material Due to the use of P or N to replace the halogen atoms, the polarity of the molecular bond segment of the epoxy resin is reduced to a certain extent, so as to improve the insulation resistance and resistance to penetration. 2 Water absorption of the material Because the N and P foxes in the nitrogen and phosphorus REDOX resin are less electron than the halogen, the probability of hydrogen bond formation with the hydrogen atom in water is lower than that of the halogen material, so the water absorption of the material is lower than that of the conventional halogen flame retardant material. For the plate, low water absorption has a certain impact on improving the reliability and stability of the material.
Why should PCB ban halogen Halogen: Halogen elements in the periodic table of chemical elements, including fluorine (F), chlorine (Cl), bromine (Br), iodine (I). At present, flame retardant substrates, FR4, CIM-3, etc., and flame retardants are mostly brominated epoxy resins. Studies by relevant institutions have shown that halogene-containing flame retardant materials (polymerized polybrominated biphenyls PBB: Polybrominated diphenyl ether PBDE (PBDE), when discarded and burned, will release dioxin Dioxin TCDD, Benzfuran (Benzfuran), etc., large smoke, odor, highly toxic gas, carcinogenic, can not be discharged after human intake, seriously affecting health. Therefore, the EU law prohibits the use of six substances such as PBB and PBDE. The same document of China's Ministry of Information Industry requires that electronic information products put on the market cannot contain lead, mercury, hexvalent chromium, polybrominated biphenyls or polybrominated diphenylethers and other subst
The most commonly used dual-head laser drilling system is the hybrid laser drilling system, which consists of an ultraviolet laser head and a CO2 laser head. This integrated hybrid laser drilling method can be used to drill copper and dielectric simultaneously. Using ultraviolet light, copper is drilled to generate the size and shape of the desired hole, followed by an open dielectric drilled with a CO2 laser. The drilling process is done by drilling a 2in X 2in block called a domain. CO2 lasers effectively remove dielectrics, even non-uniform glass-reinforced dielectrics. However, a single CO2 laser cannot make small holes (less than 75μm) and remove copper, with a few exceptions, it can remove pre-treated thin copper foils below 5μm (lustino, 2002). The UV laser is capable of making very small holes and can remove all ordinary copper street (3-36μm, 1oz, even electroplated copper foil). The ultraviolet laser can also remove the dielectric material alone, but at a slower rate. Mo
Problems related to holes in circuit board design 1, from the two aspects of cost and signal quality, choose a reasonable size of the hole size. For example, for 6-10 layers of memory module PCB, it is better to choose 10/20Mil (drill/pad) through holes, and for some high-density small-size boards, you can also try to use 8/18Mil through holes. Under current technical conditions, it is difficult to use a smaller size of the hole. For the power supply or ground wire hole, you can consider using a larger size to reduce the impedance. 2, the use of a thinner PCB board is conducive to reducing the two parasitic parameters of the hole. 3, the signal on the circuit board as far as possible not to change the layer, that is to say, try not to use unnecessary holes. 4. The pins of the power supply and the ground should be punched in the nearest hole, and the shorter the lead between the hole and the pin, the better, because they will lead to an increase in inductance. At the same time, th
High frequency circuit board in the wiring design should pay attention to matters 1) Reasonable selection of the number of layers in the PCB design of the high-frequency circuit board wiring, the use of the middle inner layer plane as a power supply and ground layer, can play a shielding role, effectively reduce the parasitic inductance, shorten the length of the signal line, reduce the cross interference between signals, under normal circumstances, the four-layer board than the two-layer board noise is 20dB lower. 2) Wiring mode When wiring the high-frequency circuit board in the PCB design, the wiring must be turned in accordance with a 45° Angle, which can reduce the transmission of high-frequency signals and the coupling between each other. 3) Line length When routing high-frequency circuit boards in PCB design, the shorter the line length, the better, and the shorter the parallel distance between two lines, the better. 4) The number of holes in the PCB design of the high-fre
PCB production process PCB production process is more complex, it involves a wide range of processes, from simple machining to complex machining, there are ordinary chemical reactions and photochemical electrochemical thermochemistry and other processes, computer-aided design CAM and other aspects of knowledge. Moreover, in the production process, there are many process problems and new problems will be encountered from time to time, and some problems will disappear without finding out the cause. Because the production process is a non-continuous form of assembly line, any problem in any link will cause the whole line to stop production or a large number of scrapped consequences. If the printed circuit board is scrapped, it can not be recycled. The job of process engineer is stressful, so many engineers leave the industry to work in sales and technical services for PCB equipment or materials manufacturers. The substrate of the board itself is made of an insulating, non-bendable mat
Soft board FPCB material characteristics The product characteristics of soft board FPCB, in addition to the soft material, in fact, there is a light texture, the configuration is very thin/very light structure, the material can be bent several times without breaking the insulation material of hard PCB, and the soft plastic substrate and wire layout of the soft board, so that the soft board can not cope with too high conduction current and voltage. Therefore, in high-power electronic circuit applications, you can hardly see the soft board design, but in small current, small power consumer electronic products, the use of soft board is quite large. Because the cost of the soft board is still subject to the key material PI, the unit cost is high, so in the product design, usually not to use the soft board as the main carrier board, but locally apply the key design that requires "soft" characteristics, such as the soft board application of the electronic zoom lens of the digital camera,
FPCB board raw materials with high heat resistance, high stability performance In the final forming products of chemical materials, PI can be used as gaskets, liners, sealing materials, bismale type materials can be used in the soft version of the multi-layer circuit circuit substrate, all aromatic materials, in the use of organic polymer materials is the highest heat resistance of the material, heat resistance temperature of up to 250~360°C! As for the bismale type PI used as a soft circuit board, the heat resistance characteristics will be slightly lower than the all-aromatic PI, generally around 200°C. bismale PI is excellent in mechanical material properties, subject to extremely low temperature changes, can maintain a highly stable state under high temperature environment, minimal creep deformation, and small thermal expansion rate! In the temperature range of -200~+250°C, the change of the material is small, in addition, bismale PI has excellent drug resistance, if 5% hydroch
① Single-sided flexible board is the lowest cost, when the electrical performance requirements are not high printed board. When wiring on one side, one side flexible plate should be selected. It has a layer of chemically etched conductive pattern, and the conductive pattern layer on the surface of the flexible insulating substrate is rolled copper foil. The insulating substrate can be polyimide, polyethylene terephthalate, arylamide fiber ester and polyvinyl chloride. The two-sided flexible plate is a conductive pattern made of a layer etched on each side of the insulating base film. Metallized holes connect the two sides of the insulating material to form a conductive path to meet the design and use of flexible functions. The covering film can protect the single and double-sided wires and indicate the position of the components. (3) Multi-layer flexible plate is to layer 3 or more layers of single-sided or double-sided flexible circuits together, through drilling holes, electrop
Process description of reverse osmosis equipment for circuit board 1, quartz sand + activated carbon + softening + security filter + reverse osmosis device + UV kill 2. Quartz sand + activated carbon + scale inhibition system + security filter + reverse osmosis device 3. Quartz sand + activated carbon + softening + security filter + primary reverse osmosis + secondary reverse osmosis + ozone sterilization 4. Flocculation settlement + quartz sand + activated carbon + scale inhibition system + security filter + reverse osmosis device 5, quartz sand + activated carbon + softening + security filter + reverse osmosis device (water production <2M3/H equipment) Characteristics of reverse osmosis equipment for circuit boards 1, reverse osmosis is at room temperature conditions, the use of no phase change physical method to make water desalination, purification. 2, water treatment relies on water pressure as a driving force, and its energy consumption is the lowest in many treatment
Five key design points of PCB circuit board 1. Have a reasonable direction Such as input/output, AC/DC, strong/weak signal, high frequency/low frequency, high voltage/low voltage, etc. Their direction should be linear (or separate) and not blend with each other. The aim is to prevent mutual interference. The best direction is in a straight line, but it is generally not easy to achieve, the most unfavorable direction is a ring, and fortunately, isolation can bring improvement. For DC, small signal, low voltage PCB design requirements can be lower. So "reasonable" is relative. 2, choose a good grounding point: the grounding point is often the most important Small ground point I do not know how many engineering and technical personnel have done much to discuss it, which shows its importance. Under normal circumstances, common points are required, such as: multiple ground lines of the forward amplifier should be joined and then connected to the main line ground, and so on. In reali
PCB sinking copper quality control method 1. Determination of chemical copper deposition rate: The use of chemical copper plating solution has certain technical requirements for copper plating rate. If the speed is too slow, it may cause holes or pinholes in the hole wall. However, if the copper deposition rate is too fast, the coating will be rough. Therefore, the scientific determination of copper sinking rate is one of the means to control the quality of copper sinking. Taking the electroless plating of thin copper provided by Schering as an example, the determination method of copper deposition rate is introduced: (1) Material: The epoxy substrate after copper corrosion is used, the size is 100×100(mm). (2) Measurement steps: A. Bake the sample at 120-140℃ for 1 hour, and then weigh W1(g) with an analytical balance; B. Corroded in 350-370 g/l of chromic anhydride and 208-228 ml/l of sulfuric acid mixture (temperature 65℃) for 10 minutes and washed with clean water; C. Treatme
Why is the circuit board required to be very flat In the automatic insertion line, if the printed board is not smooth, it will cause inaccurate positioning, and the components can not be inserted into the holes of the board and the surface mount pad, and even break the automatic insertion machine. The board on which the components are installed is bent after welding, and the component feet are difficult to cut neatly. The board can not be installed in the chassis or the socket in the machine, so the assembly plant encountered the board is also very troublesome. At present, printed boards have entered the era of surface installation and chip installation, and the requirements of assembly plants for board warping must be more and more stringent. Standard and test method for warpage According to the United States IPC-6012 (1996 edition) "Specification for Identification and Performance of Rigid Printed Boards", the maximum allowable warping and distortion for surface-mounted printed
1, engineering design: printed board design should be noted: A. The arrangement of interlayer semi-cured sheets should be symmetrical, such as six-layer plates, and the thickness between 1 ~ 2 and 5 ~ 6 layers and the number of semi-cured sheets should be consistent, otherwise it is easy to warp after lamination. B. Multi-layer core board and semi-cured sheet should be made of the same supplier. C. The line graphic area of the outer A side and B side should be as close as possible. If the A side is a large copper side, and the B side is only a few lines, the printed board is easy to warp after etching. If the line area difference between the two sides is too large, some independent grids can be added on the thin side to balance. 2. Drying plate before cutting: The purpose of drying the copper clad plate before cutting the material (150 degrees Celsius, time 8±2 hours) is to remove the moisture in the plate, while the resin in the plate is completely cured, further eliminating
About Us Product Center Capabilities&Applications Quality Assurance News Contact Us
ISO 9001:2008 registered © 2022 Shenzhen Knownpcb Technology Co., Ltd. All Rights
Reserved ICP: 粤ICP备08036040
Inquiry Now
EN
CN
中文
Home > 
