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  • How thick can the thickest heavy copper pcb boards?
    How thick can the thickest heavy copper pcb boards?
    • 2019-12-13

    How thick can the thickest heavy copper pcb boards? Fast turn pcb can be as thick as 6 OZ. However, considering the side erosion factor, pay special attention to the line width and line spacing of the inner layer if the copper thickness exceeds 3 OZ. Inner layer 3 OZ: line width and line spacing 6 / 7mil.       Outer layer 3 OZ: line width and line spacing 8 / 12mil Inner layer 4 OZ: line width and line spacing 8 / 11mil.     Outer layer 3 OZ: line width and line spacing 9 / 15mil Inner layer 5 OZ: Line width and line spacing 10/16 mils   Outer layer 3 OZ: Line width and line spacing 11/16 mils 6 OZ in inner layer: 12 / 18mil line width and line spacing 3 OZ in   outer layer: 14 / 18mil line width and line spacing

  • 10 easy mistakes PCB designers make
    10 easy mistakes PCB designers make
    • 2019-12-13

    Here's Fast turn pcb to show you what are the top 10 mistakes that PCB circuit board designers make: 1, the definition of processing level is not clear Single-panel design is in the TOP layer. If you do not specify the pros and cons, the board may be made with components and not easy to solder. 2, the large area copper foil is too close to the outer frame Large-area copper foil should be at least 0.2mm away from the outer frame. When milling the copper foil, it is easy to cause the copper foil to warp and cause the solder resist to fall off. 3, draw pads with padding Drawing pads with pads can pass DRC inspection when designing the circuit, but it is not possible for processing. Therefore, soldering data cannot be generated directly for pads of the same type. When the solder resist is applied, the pad area will be covered by the solder resist, resulting in devices. Difficult to weld. 4. The electrical ground layer is both a flower pad and a connection Because it is designed as a flower pad power supply, the ground layer is the opposite of the image on the actual printed board. All connections are isolated lines. Care should be taken when drawing several sets of power supplies or several types of ground isolation lines. A short circuit in the power supply should not cause the connection area to be blocked.   5, the characters are misplaced SMD solder pads for character cover pads, which bring inconvenience to printed board on-off test and component welding. Character design is too small, making screen printing difficult, and too large will make characters overlap each other and difficult to distinguish. 6.Surface mount device pad is too short This is for the continuity test. For too dense surface-mount devices, the distance between the two feet is quite small, and the pads are quite thin. The test pins must be staggered up and down. For example, the pad design is too short. Affects the device installation, but can make the test pin staggered. 7. Single-sided pad aperture setting Single-sided pads are generally not drilled. If drilling is required, the hole diameter should be designed to be zero. If a numerical value is designed, when the drilling data is generated, the hole coordinates appear at this position, and a problem occurs. Single-sided pads, such as drilled holes, should be specially marked. 8, pad overlap During the drilling process, the drill will be broken due to multiple drilling in one place, resulting in hole damage. The two holes in the multilayer board overlapped, and after drawing the negative, it appeared as an isolation disk, which caused scrap. 9. There are too many padding blocks in the design or the padding blocks are filled with very thin lines  The light drawing data is lost, and the light drawing data is incomplete. Because the filling blocks are drawn with lines one by one when processing light drawing data, the amount of light drawing data generated is quite large, which increases the difficulty of data proces...

  • The reason and Solutions of Circuit Board Holes Without Copper
    The reason and Solutions of Circuit Board Holes Without Copper
    • 2019-12-13

    Today I will introduce to you the reasons and solutions for copper holes in circuit boards.   The reason: 1. Deslagging is insufficient or excessive (resulting in resin washing and poor washing). 2. The dust in the drilled holes becomes detached. 3. Hole wall crack or inner layer split after drilling. 4. The neutralization treatment after removing the rubber slag does not sufficiently flush, causing the basic stannate compounds to remain in the pores. 5. Imbalanced ratios of cleaning and degreasing liquid concentration affect Pd adsorption. 6. The bottom of the concentration of the activation solution affects the adsorption of Pd. 7. Accelerated processing is excessive, and Pd is also removed at the same time as Sn is removed. 8. Poison activity of chemical copper cylinder is poor. 9. The gas in the chemical reaction cannot escape, making the metal Pd unable to form a reaction. 10. There are air bubbles in the holes. 11. Insufficient water washing in each section causes each tank's medicine to contaminate each other.      Solution: 1. Drilling quality control, roughness control, enhanced high-pressure water washing of plate mill. 2. Check the drill bit quality, turning speed and laminating conditions of the laminated board. 3. Check the process of removing slag and reduce the strength of removing slag. 4. Check the neutralization process. 5. Check if the cleaning process (temperature, concentration, time) and by-products are excessive in the cleaning section. 6. Check the activation process and replenish the activator. 7. Check the process conditions (temperature, concentration, time) to reduce the accelerator concentration and immersion time. 8. Check the NaOH. HCHO .CU2 + concentration temperature. 9. Strengthen swing, vibration, air agitation, etc. 10. Check the washing ability, water quantity and time.

  • Basic knowledge and classification of PCB circuit boards
    Basic knowledge and classification of PCB circuit boards
    • 2019-12-12

    Printed circuit boards are closely related to our lives, such as our commonly used computers, refrigerators, etc. Its various powerful functions are realized by the support of circuit boards, thereby making our lives more colorful. The following editors understand the circuit board from the simplest basis. The PCB board is actually a circuit board. Its full name is Printed Circuit Board, so it is also called a PCB board. Other names are: circuit board, aluminum substrate, high frequency board, thick copper board, impedance board, ultra-thin circuit board, Ultra-thin circuit boards, printed (copper etch technology) circuit boards, etc. After introducing the name, the classification is next. The circuit boards are divided into three major categories: single-panel, double-panel and multi-layer circuit boards. Single panel: On the most basic PCB, the parts are concentrated on one side, and the wires are concentrated on the other side. Because the wires only appear on one side, we call this PCB a Single-sided. Because the single panel has many strict restrictions on the design of the circuit (because there is only one side, the wiring cannot cross each other and must go around its own path), so only early circuits used this type of board. Single panel is usually simple to make and low in cost, but it has the disadvantage that it cannot be applied to too complicated products.   The single-panel wiring diagram is mainly screen printing, that is, a resist is printed on the copper surface. After etching, it is marked with a solder resist. Finally, the part guide hole and shape. In addition, some small and diverse products use a photoresist to form patterns. Dual-panel: It is an extension of single-panel. When single-layer wiring cannot meet the needs of electronic products, double-panel will be used. Both sides have copper clad and traces, and the lines between the two layers can be connected through vias to form the required network connection. Strictly speaking, dual-panel is a very important type of PCB in the circuit board. Its use is very large. It is easy to see if a PCB is a dual-panel. I believe that friends can fully understand the single-panel. Hold it, the double panel is an extension of the single panel, which means that the circuit of the single panel is not enough to turn to the reverse side. Another important feature of the double panel is that it has vias. To put it simply, it is a double-sided wiring, and there are lines on both sides! The sentence is: a double-sided wiring board is a double-sided board! Some friends will ask, for example, a board with double-sided wiring, but only one side has For electronic parts, is such a board a double-sided board or a single-sided board? The answer is obvious. Such a board is a double-sided board, and only the parts are mounted on the double-sided board. Multilayer board: refers to a printed board with more than three conductive pattern layers and insulation material laminated between them, and...

  • How PCB Array improves efficiency?
    How PCB Array improves efficiency?
    • 2019-12-12

    1. The outer frame (clamping edge) of the PCB array should adopt a closed loop design to ensure that the PCB array will not be deformed after being fixed on the fixture; 2. PCB assembly width ≤260mm (SIEMENS line) or ≤300mm (FUJI line); if automatic dispensing is required, PCB assembly width × length≤125 mm × 180 mm; 3. The shape of the PCB array as close to a square as possible. It is recommended to use 2 × 2, 3 × 3,…. 4. The center distance between the small plates is controlled between 75 mm and 145 mm; 5. When setting the reference positioning point, usually leave a solderless area larger than 1.5 mm around the positioning point; 6. There must be no large devices or protruding devices near the connection points between the outer frame of the PCB and the internal small board, and between the small board and the small board, and there must be more than 0.5mm of space between the edges of the components and the PCB board. To ensure the normal operation of the cutting tool; 7. Four positioning holes are opened at the four corners of the outer frame of the PCB. The hole diameter is 4mm ± 0.01mm; the strength of the hole must be moderate to ensure that it will not break during the upper and lower plates. glitch; 8. Each small board in the PCB array must have at least three positioning holes, 3 ≤ aperture ≤ 6 mm, and no wiring or patch is allowed within 1 mm of edge positioning holes; 9. The reference symbols used for PCB positioning and fine-pitch device positioning. In principle, QFPs with a pitch of less than 0.65mm should be set at their diagonal positions; the positioning reference symbols used for imposition PCB daughter boards should be paired Use, place diagonally to the positioning element; 10. Large components need to have positioning posts or positioning holes, such as I / O interface, microphone, battery interface, micro switch, headphone interface, motor, etc

  • Can the printed circuit board be dirty use alcohol clean?
    Can the printed circuit board be dirty use alcohol clean?
    • 2019-12-11

    Can the printed circuit board be dirty and cleaned with alcohol? Let's take a look. The PCB board can be cleaned with alcohol, and the spray paint of the circuit board is not dissolved in alcohol and will not melt and fall off due to cleaning with alcohol. Alcohol does not contain electrolytes and does not produce conductive short circuits. Alcohol can wipe away greasy and deposited dust, making the circuit board as smooth as ever. Alcohol is easy to volatilize, it will dry out in a ventilated place for a few minutes without residue. Cleaning method: After the circuit board is removed, it is best to blow off the dust with a hair dryer, and then use a soft brush to remove the adhered dust and dust in the corners, then wipe it gently with alcohol cotton yarn, and dry it in a ventilated place. Caution: Do not wash with water or other solvents, do not dip, so as not to damage the components on the circuit board.

  • 4 special plating methods for Printed circuit board plating
    4 special plating methods for Printed circuit board plating
    • 2019-12-10

    This article mainly introduces 4 special plating methods in circuit board welding. First, finger-type plating It is often necessary to plate rare metals on board-side connectors, board-side protruding contacts or gold fingers to provide lower contact resistance and higher abrasion resistance. This technology is called PCB manufacturing finger-plating or protruding part plating. Gold is often plated on the protruding contacts of the board-side connector with nickel plating on the inner layer. The gold fingers or the protruding parts of the board edges are manually or automatically plated. At present, the gold plating on the contact plug or gold finger has been plated with rhenium and lead. Instead of plated buttons. The process is as follows: 1) Strip coating to remove tin or tin-lead coating on protruding contacts 2) Rinse with washing water 3) Scrub with abrasive 4) Activation is diffused in 10% sulfuric acid 5) Nickel plating thickness on the protruding contacts is 4 -5μm 6) Wash and remove mineral water 7) Treatment of gold osmotic solution 8) Gold-plated 9) Cleaning 10) drying Second, through-hole plating There are many ways to create a desirable plating layer on the hole wall of the substrate. This is called hole wall activation in industrial applications. PCB prototype requires multiple intermediate storage tanks for the commercial PCB production process. Each storage tank has its own control and maintenance requirements. Through-hole plating is a necessary follow-up process of the drilling process. When the drill drills through the copper foil and the substrate below it, the heat generated causes the insulating synthetic resin that forms the majority of the substrate to melt, the molten resin and other drilling debris. It accumulates around the holes and coats the newly exposed hole walls in copper foil, which is actually harmful to subsequent electroplated surfaces. The molten resin will also leave a layer of hot axis on the hole wall of the substrate, which shows poor adhesion to most activators. This requires the development of a class of technologies similar to stain removal and etch back chemistry. One method that is more suitable for the PCB prototyping  is to use a specially designed low-viscosity ink to form a highly adhesive, highly conductive film on the inner wall of each through hole. In this way, there is no need to use multiple chemical treatment processes, only one application step, followed by thermal curing, can form a continuous film on the inside of all hole walls, and it can be directly plated without further processing. This ink is a resin-based substance that has very strong adhesion and can be easily bonded to most thermally polished hole walls, thus eliminating the etch-back step. Third, the reel interlocking selective plating The pins and pins of electronic components, such as connectors, integrated circuits, transistors, and flexible printed circuits, are all plated to achieve good contact resistance and corr...

  • Why do PCBs need to be cleaned?
    Why do PCBs need to be cleaned?
    • 2019-12-10

    When troubleshooting non-functional or poorly performing circuits, engineers can often run simulations or other analysis tools to consider the circuit at the schematic level. If these methods don't solve the problem, even the best engineers may be frustrated, frustrated or confused. In order to avoid getting into similar dead ends, I will introduce a simple but very important tip: keep it clean! What does that mean? If the PCB is not properly cleaned, certain materials used during PCB assembly or modification may cause serious circuit functionality issues. One of the most common problems with this phenomenon is flux. Figure 1 shows a PCB with too much flux remaining Flux is a chemical used to assist in soldering components to a PCB. But unfortunately, if it is not cleaned after soldering, the solder will degrade the surface insulation resistance of the PCB, which will seriously degrade the circuit performance in the process! Picture 2 Figure 2 shows a test circuit showing the results of solder contamination. A balanced Wheatstone bridge network activated by a 2.5V reference voltage emulates a high-impedance bridge sensor. Differential bridge sensor outputs VIN +-VIN- can be connected to the INA333 with a gain of 101V / V. In an ideal state, because the bridge is in equilibrium, VIN +-VIN- = 0V. But flux contamination will cause the actual bridge sensor voltage to drift slowly over time. In this test, the changes of VIN- and VOUT for one hour after cleaning at different levels were recorded at the same time after assembly: uncleaned; manual cleaning, air-drying; ultrasonic cleaning, air-drying, baking. Picture 3 As can be seen from Figure 3, solder contamination has a serious impact on the bridge sensor output performance. Without cleaning or manual cleaning, even after the settling time, the bridge sensor voltage never reached the expected voltage of about VREF / 2. In addition, uncleaned boards also exhibit a large amount of external noise collection. However, after cleaning with an ultrasonic bath and drying completely, the bridge sensor voltage is as stable as a rock. Picture 4 Observing the output voltage of the INA333, you will continuously see the performance degradation caused by improper cleaning. Uncleaned circuit boards experienced DC errors, long stabilization times, and severe external noise collection; manually cleaned circuit boards exhibited strangely low frequency noise and eventually found their root cause — due to air conditioning cycles inside the test facility ; Correctly cleaned and dried circuit boards performed well, no drift occurred at any point during the test.   The conclusions show that improper flux cleaning can cause severe performance degradation, especially in high-precision DC circuits. Therefore, for all PCBs that have been manually assembled or modified, be sure to use an ultrasonic bath (or similar) for final cleaning. After air-drying with an air compressor, the PCB is assembled and cleaned at a slightly ...

  • What is the normal copper thickness of the Printed circuit board?
    What is the normal copper thickness of the Printed circuit board?
    • 2019-12-09

    The holes on the circuit board are generally divided into copper holes and non-copper holes. The main role of the non-copper holes is for positioning and installation. Generally, the holes are larger than 0.8mm. Via holes are generally plug-in or via holes. The most common holes on pcb boards should be via holes (via holes). The hole diameter of the plug-in hole is larger than the size of the via hole, which is generally above 0.5. Based on the inserted capacitor and resistance. , Sockets and so on.   The via hole mainly plays a role of conduction. The hole diameter is generally small, and the common hole diameter is less than 0.3. With the increase of precision boards, the product function requirements increase, the number of circuit board layers increases, and the hole diameter becomes smaller and smaller. The smallest hole diameter 0.1mm. Requires laser drilling. The vias need to be conductive, and a copper skin is required to conduct them. Therefore, the thickness, saturation, and copper quality of the holes naturally become the key to the later work of the circuit board.   In general, the thickness of the copper wall of the pcb board is 10um-20um, and products with larger current requirements may require more than 25.4um. Because hole copper is electroplated later, unlike surface copper, which comes with raw materials, the quality of hole copper depends on the production and processing of the later circuit board factory. Length of plating time, working quality of plating line, etc. Generally, a saturated copper plate is required. It is hoped that enough time is provided on the plating line, otherwise it is easy to cause insufficient copper, and the copper ball also needs to be pure and hurry, otherwise it will cause blistering. Insufficient copper can cause the circuit board to interrupt the circuit during the later working process, or burn out.

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