The definition of the impedance plate is: a good laminated structure can play a role in controlling the characteristic impedance of the printed circuit board, and its wiring can form an easily controlled and predictable transmission line structure called the impedance plate.If you want to order PCB product, please check and custom your order online.Impedance characteristics According to the theory of signal transmission, the signal is a function of time and distance variables, so every part of the signal may change on the connection. Therefore, determine the AC impedance of the connection, that is, the ratio of the change in voltage to the change in current as the characteristic impedance of the transmission line (Characteristic Impedance): the characteristic impedance of the transmission line is only related to the characteristics of the signal connection itself. In the actual circuit, the resistance value of the wire itself is less than the distributed impedance of the system, especially in high-frequency circuits, the characteristic impedance mainly depends on the distributed impedance caused by the unit distributed capacitance and unit distributed inductance of the connection. The characteristic impedance of an ideal transmission line depends only on the unit distributed capacitance and unit distributed inductance of the connection.Impedance calculation The proportional relationship between the rising edge time of the signal and the time required for the signal to reach the receiving end determines whether the signal connection is regarded as a transmission line. The specific proportional relationship can be explained by the following formula: If the length of the wire on the PCB is greater than l/b, the connecting wire between the signals can be regarded as a transmission line. From the calculation formula of the signal equivalent impedance, the impedance of the transmission line can be expressed by the following formula: at high frequencies (tens of megahertz to hundreds of megahertz), wL>>R is satisfied (of course in the range of signal frequency greater than 109 Hz, then Considering the skin effect of the signal, this relationship needs to be carefully studied). Then for a certain transmission line, its characteristic impedance is a constant. The reflection phenomenon of the signal is caused by the inconsistency between the characteristic impedance of the driving end of the signal and the transmission line and the impedance of the receiving end. For the CMOS circuit, the output impedance of the driving end of the signal is relatively small, which is tens of ohms. The input impedance of the receiving end is relatively large.Impedance control There are various signal transmissions in the conductors in the circuit board. When the transmission rate must be increased, the frequency must be increased. If the circuit itself is different due to factors such as etching, stack thickness, and wire width, it will cause the impedance value to change, making it The signal is distorted. Therefore, the impedance value of the conductor on the high-speed circuit board should be controlled within a certain range, called "impedance control". The factors that affect the impedance of the PCB traces include the width of the copper wire, the thickness of the copper wire, the dielectric constant of the medium, the thickness of the medium, the thickness of the pad, the path of the ground wire, and the traces around the trace. Therefore, when designing the PCB, the impedance of the traces on the board must be controlled to avoid signal reflection and other electromagnetic interference and signal integrity problems as much as possible to ensure the stability of the actual use of the PCB board. The calculation method of the impedance of the microstrip and stripline on the PCB board can refer to the corresponding empirical formula.Impedance matching In the circuit board, if there is signal transmission, it is hoped that from the sending end of the power supply, in the case of minimum energy loss, it can be smoothly transmitted to the receiving end, and the receiving end absorbs it completely without any reflection. To achieve this transmission, the impedance in the line must be equal to the impedance inside the sending end to be called "impedance matching". When designing high-speed PCB circuits, impedance matching is one of the design elements. The impedance value has an absolute relationship with the wiring method. For example, whether it is walking on the surface layer (Microstrip) or inner layer (Stripline/Double Stripline), the distance from the reference power layer or ground layer, the width of the trace, the PCB material, etc. will affect the characteristic impedance value of the trace. In other words, the impedance value must be determined after wiring, and the characteristic impedance produced by different PCB manufacturers also has slight differences. Generally, the simulation software will not be able to consider some wiring with discontinuous impedance due to the limitations of the line model or the mathematical algorithm used. At this time, only some terminations (Temninators), such as series resistance, etc., can be reserved on the schematic. Alleviate the effect of trace impedance discontinuity. The real fundamental solution to the problem is to try to avoid impedance discontinuities when wiring.definition:Definition of characteristic impedance: At a certain frequency, in the transmission signal line of an electronic device, relative to a certain reference layer, the resistance of its high-frequency signal or electromagnetic wave during propagation is called characteristic impedance, which is electrical impedance, inductance A vector sum of reactance, capacitance reactance...Classification of characteristic impedance:Common characteristic impedances are divided into: single-ended (line) impedance, differential (dynamic) impedance, coplanar impedance, etc.Single-ended (line) impedance: English single ended impedance refers to the impedance measured by a single signal line.Differential (dynamic) impedance: English differential impedance, refers to the impedance measured in two transmission lines of equal width and equal interval during differential driving.Coplanar impedance: English coplanar impedance, which refers to the impedance measured when the signal line is transmitted between its surrounding GND/VCC (the distance between the signal line and the GND/VCC on both sides is equal).Determining conditions for impedance control requirements: when the signal is transmitted in the PCB wire, if the length of the wire is close to 1/7 of the signal wavelength, the wire at this time becomes a signal transmission line, and generally the signal transmission line needs to be impedance controlled. During PCB production, it is determined whether the impedance needs to be controlled according to the customer's requirements. If the customer requires impedance control for a certain line width, the impedance of the line width needs to be controlled during production.Three elements of impedance matching: output impedance (original active part) characteristic impedance (signal line) input impedance (passive part) (PCB board)Impedance matchingWhen the signal is transmitted on the PCB, the characteristic impedance of the PCB must match the electronic impedance of the head and tail components. Once the impedance value exceeds the tolerance, the transmitted signal energy will be reflected, scattered, attenuated or delayed, resulting in The signal is incomplete and the signal is distorted.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 04/28/2021 10:49
PCB is the most important part of electronics. PCB in computers to calculators, PC board material selection should be undertaken with care and knowledge for electrical necessities of a given piece of equipment. Usually, PCB is a flat laminated composite made from non-conductive substrate materials with layers of copper circuitry buried internally or on the external surfaces. They can be as simple as 1 or 2 layers of copper, or in high density applications they can have 50 PCB layers or more. The flat composite surface is ideal for supporting the components that are soldered and attached to the PCB, while the copper conductors connect the components to one another electronically. And why PCB materials are very important to PCB manufacturing? PCB manufacturing involves many steps—depositing metal and photo resist layers, imaging, etching, and stripping—all of which require materials tailored for a specific function. Whether they remain on the board or are removed during the manufacturing process, all PCB materials affect the performance and reliability of the final product.If you want to order PCB product, please check and custom your order online.What are the different types of PCB material? There are main different popular types of PCB material: 1. Metal: Metals like copper, aluminum, and iron are generally used as the conductive layer in PCBs. Among of them, copper is the most popular. That is why most PCBs are “copper clad.” Every metal selected for use in PCBs supports the use of surface mount technology or SMT components. This is where you apply the solder mask to the metal traces and heat the board to solder the components into place. You can then do a quick quality check and test before sending the assembled PCB downstream. 2. PTFE: And the second type of material used in PCB manufacturing is PTFE, also as known as Teflon. It is a pretty strong, lightweight, and flexible material. PTFE is preferred in applications with very tight tolerances because it doesn’t expand much on exposure to high temperatures. Another point in favor of this material is that it is flame resistant. 3. FR-4: As the most commonly used material in PCBs, Most of us have seen the green FR-4 board to which the electrical components are mounted, though it comes in other colors. It is a glass reinforced epoxy laminate sheet. It is a composite made of woven fiberglass cloth and a flame-resistant epoxy resin binder. The epoxy used is flame retardant and water resistant. It provides good strength to weight ratios. The tensile strength offered by FR-4 is very high. FR itself stands for flame resistance. Most FR-4 boards have bromine in the epoxy laminate to help extinguish flames. One point in favor of FR-4 is that it doesn’t absorb moisture. 4. Polyimide laminates: Polyimide laminates offer higher temperature performance than FR4 materials as well as a slight improvement in electrical performance properties. Polyimides materials cost more than FR4 but offer improved survivability in harsh and higher temperature environments. They also are more stable during thermal cycling, with less expansion characteristics, making them suitable for higher layer count constructions. 5. Flexible laminates: Flexible laminates are thin and provide the ability to fold the electronic design, without losing electrical continuity. They do not have glass fabric for support but are built on plastic film. They are equally effective folded into a device for a one-time flex to install application, as they are in dynamic flex, where the circuits will be folded continuously for the life of the device. Flexible laminates can be made from higher temperature materials , or very low-cost materials such as polyester and PEN. Because the flexible laminates are so thin, manufacturing flexible circuits also can require a uniquely skilled workforce, specialized equipment, processing and an anticipation of lower manufacturing yields. 6. Others: There are many other laminates and bonding materials on the marketplace including BT, cyanate ester, ceramics, and blended systems that combine resins to get distinct electrical and/or mechanical performance characteristics. Because the volumes are so much lower than FR4, and the manufacturing can be much more difficult, they are usually considered expensive alternatives for PCB designs. The different materials used for the fabrication of PCBs, all offer a variety of advantages and disadvantages. The material is chosen according to the application, the result needed, environmental factors, and any other constraints the PCB will face. You should choose the material of the PCB depending on the results that are expected. Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 04/27/2021 17:52
There are many factors coming into play when purchasing and manufacturing a PCB such as profile, weight, and the components. However, among all of them the most important factors is the PCB thickness. The thickness of PCB affects its conductivity and resistance, significant considerations that have to match the customers’ requirements. Usually, the PCB thickness has a significant role in its functionality. When relating to dimensions for manufacturing applications, the standards are critical to understand and work with. This is especially true for circuit boards. Though there is no official standard for PCB thickness, certain sizes are preferred and commonly used among manufacturing companies. These preferred thicknesses are highly recommended to simplify design, effectively leverage manufacturing equipment and minimize costs. However, PCB thickness can vary, and many designers may choose to alter PCB thickness for specific design and manufacturing purposes. As each design has its certain thickness and functionality level, so knowing some knowledge about PCB thickness and knowing how to select the thickness of your PCB design is essential. Let’s get to know the levels of thickness available and how you can determine the right standards for your requirements.If you want to order PCB product, please check and custom your order online. Standard PCB thickness PCB board thickness The board thickness is always based on both the insulating material and the top layer material; at the beginning of Circuit boards, this would be Bakelite sheet included as the top layer of the plywood at the end the total thickness of the board would lead to 0.065inches. Over time, the use of better substrates other than plywood started being used. For instance, epoxy or the paper reinforced phenolic resins are among the substrates used between layers of copper foil. Consequently, the use of lighter materials in addition to the lack of use of the edge connectors, the board thickness is at times below 0.0065". Copper PCB thicknessBeing the dictator of a PCB's functionality and area of application, its thickness has an essential role in achieving the standard PCB thickness. It is achieved by spreading an ounce of copper evenly over a square foot area, which results in 1.37 mils (1.37 thousandths of an inch). Usually, the Printed Circuit Board is around 1 oz with 1.4 mm to 2.8mm thickness for the internal layer, at the end; the finished weight would be about 2 oz to 3oz which can be adjusted based on your preference. PCB trace thicknessThe PCB trace thickness is the thickness determined by the designer, and it is one of the essential parameters in PCB designing. It is specified in the designer Garber files to prevent overheating or damaging the PCB. Therefore, the path should be thick enough to allow higher current passage without affecting the average temperature of the PCB. As for trace thickness of a PCB board, you are talking about the preferable thickness decided by the designer during the design process, the most used trace thickness ranges from 0.008 inches to 0.240 inches with particular attention paid to 0.2 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.6 mm, 2.0 mm, 2.3 mm, and so on. When design multiple layer boards of 4 or more layers, the user can choose ½, 1 or 2 ounce inner layer copper foil for his board. The Fr-4 material is a structure mainly composed of fiberglass weaved to a thin and cloth-looking sheet. It is the fiberglass that gives the Fr-4 popularity as a solid base for the manufacturing of rigid circuit boards. It is enclosed with a fire-resistant epoxy resin, and it is where the rigidity comes from. Standard PCB Fr-4 thicknessThe Fr-4 standard PCB thickness is measured in millimeters or inches. The use of either calibration depends on what the designer or manufacturer prefers. Due to the widespread use of the Fr-4 substrate, the range of its subsequent board thickness can go to some extreme. It is usually from 3" to 10". Design Requirements: Most manufacturers prefer thicker boards to thinner ones. Why? With Fr-4 substrate, narrower boards are more likely to get broken when they are too big. Also, they lack groove features. On the other hand, thicker boards are spectacularly flexible and have groove features. Therefore, it would be wise to consider the extra weight of a PCB. Flexibility: It is debatable whether flexibility arises from thinner or thicker boards, but the right answer would be- it depends on where the PCB is being used and its application. Let us take an example of applying the Electronic Control Unit in the medical field; thinner boards ensure you encounter less stress. In this situation, narrower boards result in very flexible PCBs. Impedance Matching: The thickness of the board is essential when dealing with multilayer boards since impedance matching is crucial. That is as the layers create the dialectic, which facilitates impedance control. Standard PCB core thicknessPCB core is the layer containing the Fr-4 substrate sandwiched by copper foils as manufactured in a core factory. In the making of a standard PCB core, some items have to be put in place. The copper foils used to form the Fr-4 core layer should be smooth and with a very exact thickness. Nevertheless, there are situations a manufacturer may call fortunate while the thickness requirements are still not met, and the PCB works just fine. That means the PCB core materials are not critical to performance, and all along the customer does not notice. The weight of the measurements of the core thickness range from half an ounce to 3 ounces, in between which an exact size is made based on the PCB desired functionality. Note that the resultant weight includes the copper foils, which are of similar value on either side. However, if you can have a core thickness with a suitable copper weight, you can use some pre-preg sheets in dielectric positions to achieve your final consistency. That is not necessarily provided during the design, especially where there is no need for impedance control. Standard 2 layer PCB thicknessWith the advancement in Technology, Multiple Board layers became a thing as the layers allowed for more loads all while still retaining a thickness of 63mm. Since the layer counts for the PCBs were increased to match up to the wiring requirements of the more complex circuits, the circuit boards were also produced to have a higher layer counts. That brought about the jump from the standard PCB thickness of 63mils to 93mils. However, with high-temperature materials, Isola’s 370HR can be used in scores of 8, 10, 14, 22 or 39mils respectively. In other words, the standard PCB thickness depends on the layers of your foil lamination. If the foil lamination is for a four-layer PCB, the standard to be used should be .031+/-10%. For a six-layer foil lamination, the best standard to be used should be .062+/-10% or .031+/-10% respectively. For 8 and ten layer boards, the standard PCB thickness is at 0.062, 0.093 and 0.125 inches.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 04/27/2021 17:46
Before we are talking about PCB layers, it is necessary to have a clear perception of layers. All the layers are responsible for assembly or building a PCB, and they are the basic of PCB. A layer is the signal conducting levels that are vertical to the PCB plane. And you’ll find a 2-layer PCB having a top and bottom layer. For a 4-layer PCB, for instance, you’ll find a top, inner 1, inner 2, and bottom layer. And the same thing applies for other PCB layers. Generally, regular PCBs consist of solder masks on the outer copper layer. And you can find the solder masks on both the top and bottom copper layers. Besides, the solder masks get applied either as liquid or as a sheet on the PCB layers. Plus, they have printed openings with a subtractive photographic procedure. Overall, PCB layers are the foundation blocks of a PCB. So, they include the copper, the dielectric material, and one more thing. And it’s the trace dimensions aligned with the dimension or mechanical layer.If you want to order PCB product, please check and custom your order online. PCB layers tutorialsThere are 3 kinds of tutorials that make the PCB layers complete: Dielectric materials The dielectric materials offer two critical functions for PCBs. And all that happens as the PCBs run rapid signals. The dielectric materials help to isolate signals on adjacent PCB layers. The stability of a PCB highly depends on the steady impedance of dielectric materials. CopperThe various weight and thickness of copper in a PCB impacts too. Of course, it influences the capacity of the PCB to attain the right amount of current flow. Also, it helps to describe the amount of current loss. The quality of copper in a PCB impacts the impedance of a ground plane. Besides, it affects the power plane’s thermal conductivity. Trace DimensionsThey help to provide PCB foundational measurements. Besides, the assembly information helps to regulate the location and mounting of electronic devices. What are the types of PCB layers? By numbersUsually, the layers in the PCB are so tightly integrated, so it's not always easy to see the actual number, but if you look closely at the motherboard, you can see it. PCB board has the following three main types of division: Single-layered boards On the most basic PCB, the parts are concentrated on one side and the wires on the other. This type of PCB is called a single panel because the wire appears on only one side. Double-layered boardsThis board has wiring on both sides, but to use the wiring on both sides, there must be a proper electrical connection between the two sides. This "bridge" between circuits is called a guide hole. A guide hole is a small hole in a PCB filled or coated with metal that can be connected to wires on both sides. Multi- layered boardsIn order to increase the area that can be wired, multi-layered board uses more single or double-sided wiring boards. With a double lining, two one-way for outer layer or two double lining, two blocks of single outer layer of the printed circuit board, through the positioning system and alternate insulation adhesive materials and conductive graphics interconnection according to design requirement of printed circuit board becomes four, six layer printed circuit board, also known as multilayer printed circuit board. By function Mechanical LayerThe function of a mechanical layer is to reveal information about the PCB assembly methods and printing. So, you can choose to have more than one mechanical layer. It can be a complicated shape or a simple rectangle. Overlay / Silkscreen LayersThe Silkscreen layer consists of the Bottom and Top overlay. And it’s useful for putting text information. Besides, it’s crucial to get separate files, for the fabricator, to the bottom and top overlays. Routing LayersRouting layers are in the internal and external parts of a PCB. Also, it’s a layer that designers took time to perfect. Plus, it’s useful for component interconnection. Before you create your board, it’s necessary to provide the routing layers to your fabricator. Solder Mask LayersA solder mask layer is what you see when you hold a PCB. That is, it’s a thin green protective covering. And it usually helps to cover the board’s top and bottom. If there’s debris on your board, this board will help you protect traces from shorting. Solder Paste LayersA solder paste comes in handy when you have surface mounts components. So, this layer helps to bond the component pin to the surface (copper) of your board. Also, it improves the flow of the solder. Keep Out LayerThis layer shows the limit of the working area of your board design. It will show if there’s any violation of the pre-set boundaries.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 04/26/2021 18:12
PCB layout, as the most basic process, transfer a circuit from a breadboard to a more stable and permanent physical form. As a link in the design process and also a very important link, In the case of reasonable hardware circuit design, it is actually an absolutely important index that affects performance. PCB layout is a very advanced engineering tool for board design with intelligent manual routing of high-speed and differential signals, shape-based auto router, advanced verification, and wide imports and exports capacity. Of all the PCB manufacturing process, PCB layout is a very important step and preparatory work to complete the product design.If you want to order PCB product, please check and custom your order online.Usually, PCB layout provide following features below:1） Smart project structure2） Placement features3） Manual routing4） Advanced verification features5） 3D PCB preview & STEP export Know about PCB layout guidelinesSince PCB is the key point of the matter, the layout is pretty critical before the whole manufacturing process. To protect against shorts and other damage, specific layout steps should be taken.Structure of PCBBefore PCB layout, it is necessary to know the basic structure of PCB.1) Base: The base material is most often made from fiberglass or glass epoxy fibers. FR4 is the most commonly used such material, but there are other options available depending on your project and other factors. One example is high-temp resistant plastic. A solid base is used to help ensure that the PCB is rigid and can hold components. With that being said, board thickness can vary dramatically from one application to another, ranging from 0.8mm to as thick as 1.6mm or even more in some cases.2) Components: A very broad range of components will need to be integrated with the PCB, including resistors, and numerous others. The number of components and their relative size will determine the size of the board, as well, although some techniques can be used to reduce the size, such as miniaturization, as well as creating double-sided PCBs and multilayer PCBs. These latter two options help you condense what would be very large PCBs into a footprint that is a fraction of the size.3) Copper: Copper is used with most PCBs, and is the metal through which electrons flow, powering the components and, ultimately, the device in which the PCB is installed. Copper may be layered directly onto the board in varying thicknesses, or copper foil may be applied instead, depending on the needs of the project. Copper is usually measured in ounces per square foot, with the most common being one ounce per square foot. However, high-capacity PCBs can hold much more copper, up to three ounces per square foot. Layout Rules1） Under normal circumstances, all the components should be arranged on the same surface of the circuit board, only when the top element is too dense, can some highly limited and small calorific devices, such as patch resistance, patch capacitance, patch IC, etc., be placed in the low level.2） Under normal circumstances, all the components should be arranged on the same surface of the circuit board, only when the top element is too dense, can some highly limited and small calorific devices, such as patch resistance, patch capacitance, patch IC, etc., be placed in the low level.3） From the edge of the circuit board is generally not less than 2MM. The best shape of the circuit board is rectangular. When the circuit board ruler is greater than 200MM by 150MM, the mechanical strength that the circuit board can withstand should be considered. Layout processComponents: It is necessary to set the location and orientation of components. Usually, you’ll maintain the same orientation for all components to help reduce soldering and routing errors. It also makes your board easier to install and test. Relational Placement: In addition to directional placement, you also need to think about relational placement. In PCB layout, to leave space between components for your traces and to help reduce heat. Routing: Routing refers to the actual placement of the traces that connect your components to each other and allow electricity to flow through the circuit. If your components are too close together, you’ll have little room for these connections. Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 04/26/2021 10:18
The circuit board must be flame-resistant. It cannot be burnt at a certain temperature but can only be softened. The temperature point at this time is called the glass transition temperature (Tg point), and this value is related to the dimensional stability of the PCB board.Tg refers to the glass transition temperature of the sheet. Normal sheet (Normal Tg) is about 130~150C, and Tg of high Tg sheet can reach 170-210C.FR4 copper clad laminate is the abbreviation of glass fiber epoxy resin clad laminate. FR4 copper clad laminate is divided into the following levels:First: FR-4 A1 grade copper clad laminateThis level is mainly used in military products, communications, computers, digital circuits, industrial instruments, automotive circuits and other electronic products. The quality of this series of products has completely reached the world-class level, the highest grade and the best performance.Second: FR-4 A2 grade copper clad laminateThis level is mainly used for ordinary computers, instruments, advanced home appliances and general electronic products. This series of copper clad laminates are widely used, and various performance indicators can meet the needs of general industrial electronic products. There is a good price-performance ratio. Can enable customers to effectively improve price competitiveness.Third: FR-4 A3 grade copper clad laminateThis level of CCL is the FR-4 product developed and produced by our company specifically for the home appliance industry, computer peripheral products and general electronic products (such as toys, calculators, game consoles, etc.). The characteristic is that the price has a competitive advantage under the premise that the performance meets the requirements.Fourth: FR-4 A4 grade copper clad laminateThis grade of plate belongs to the low-end material of FR-4 copper clad laminate. However, various performance indicators can still meet the needs of ordinary home appliances, computers and general electronic products. Their prices are the most competitive, and the performance-price ratio is also very good.Fifth: FR-4 Class B copper clad laminateThe plates of this grade are relatively poor, and the quality stability is poor. It is not suitable for circuit board products with a large area. Generally, products with a size of 100mmX200mm are suitable.
PCB Glossary ⋅ 03/13/2021 18:16
Rigid board: Generally refers to the ability of the material to not deform under the action of external force. Of course, it is an ideal rigid board that does not deform under the action of external force, but a material that undergoes a small amount of elastic deformation under a large external force is a rigid material. Rigid printed circuit boards include phenolic cellulose paper copper-clad laminates, epoxide cellulose paper laminates, polyester woven glass fabric laminates, and epoxide woven glass fabric laminates. The flexible circuit board is a printed circuit board with high reliability and high bending performance, which is made of polyimide or polyester film as the base material. Inner circuit of rigid board The copper foil substrate is first cut to a size suitable for processing and production. Before the substrate is laminated, the copper foil on the surface of the board should be roughened properly by brushing, micro-etching, etc., and then the dry film photoresist should be attached to the dry film at an appropriate temperature. Take the substrate with the dry film photoresist into the UV exposure machine for exposure. The photoresist will undergo polymerization after being irradiated with ultraviolet light in the transparent area of the negative film(the dry film in this area will be exposed in the later development and copper etching steps Keep it as an etch resist), and transfer the circuit image on the negative film to the dry film photoresist on the board. After tearing off the protective film on the film surface, first remove the wet shadow of the unexposed area on the film surface with an aqueous solution of sodium carbonate, and then corrode and remove the exposed copper foil with a mixed solution of hydrochloric acid and hydrogen peroxide to form a circuit. Finally, the aqueous film of sodium hydroxide is used to wash away the dried photoresist. For inner layer circuit boards with more than six layers (inclusive), use the automatic positioning punching machine to punch out the riveting reference holes for the alignment of the lines between the layers.Rigid plate pressing After completion, the inner circuit board must be bonded to the outer circuit copper foil with glass fiber resin film. Before lamination, the inner layer board needs to be blackened (oxidation) to increase the insulation of the copper surface; the copper surface of the inner layer circuit should be roughened to produce good bonding performance with the film. When laminating, the six-layer circuit (including the inner layer circuit board above) is riveted in pairs with a rivet machine. Then use a platter to place it neatly between the mirror steel plates and send it to a vacuum laminator to harden the film with appropriate temperature and pressure. The circuit board after pressing is locked by X-ray automatic positioning lock, and the hole is used as the reference hole for the alignment of the inner and outer layers. The edges of the board should be properly cut to facilitate subsequent processing.
PCB Glossary ⋅ 03/11/2021 22:26
Multi Layer Pcb
The double-sided board is the middle layer of media, and both sides are trace layers. A multi-layer board is a multi-layer wiring layer. Between each two layers is a dielectric layer. The dielectric layer can be made very thin. The multilayer circuit board has at least three conductive layers, two of which are on the outer surface, and the remaining layer is synthesized in the insulating board. The electrical connection between them is usually achieved through plated through holes in the cross section of the circuit board.A multilayer printed circuit board is a circuit board composed of two or more conductive layers (copper layers) superimposed on each other. The copper layer is bonded together by a resin layer (prepreg). Multi-substrate is the most complicated type of printed circuit board. Due to the complexity of the manufacturing process, lower production volume and difficulty in redoing, their prices are relatively high.Due to the increase in the packaging density of integrated circuits, it leads to a high concentration of interconnect lines, which makes the use of multiple substrates necessary. In the layout of the printed circuit, unforeseen design problems have appeared, such as noise, stray capacitance, and crosstalk. Therefore, the design of printed circuit boards must focus on minimizing the length of signal lines and avoiding parallel routes. Obviously, in a single-sided PCB or even a double-sided board, these requirements cannot be answered satisfactorily due to the limited number of crossovers that can be achieved. In the case of a large number of interconnections and cross-over requirements, to achieve a satisfactory performance of the PCB circuit board, the board layer must be expanded to more than two layers, so a multilayer circuit board has appearanced. Therefore, the original intention of manufacturing multi-layer circuit boards is to provide more freedom for selecting suitable wiring paths for complex and/or noise-sensitive electronic circuits.The multilayer circuit board has at least three conductive layers, two of which are on the outer surface, and the remaining layer is synthesized in the insulating board. The electrical connection between them is usually achieved through plated through holes on the cross section of the circuit board. Unless otherwise stated, multi-layer printed circuit boards, same as double-sided boards, are generally plated through-hole boards.The manufacturing method of the multi-layer board is generally made by the inner layer pattern first, and then the single-sided or double-sided substrate is made by the printing etching method, and it is included in the designated layer, and then heated, pressed and bonded, as for the subsequent The hole is the same as the double-sided plated through-hole method. It was invented in 1961. Simple differentiation of multilayer circuit boards The circuit board determines the process difficulty and processing price according to the number of wiring surfaces. The ordinary circuit board is divided into single-sided circuit and double-sided circuit. It is commonly known as single-sided board and double-sided board. In addition to the surface circuit, multiple layers of circuits can be superimposed inside. During the production process, after each layer of circuit is made, it is positioned and pressed by optical equipment, so that the multilayer circuit is superimposed on a circuit board. Commonly known as multilayer circuit boards. Any circuit board greater than or equal to 2 layers can be called a multilayer circuit board. Multilayer circuit boards can be divided into multilayer rigid circuit boards, multilayer flex-rigid printed circuit boards . The birth of multilayer circuit boards Multi-substrates are manufactured by stacking two or more circuits on top of each other, with reliable pre-defined interconnections between them. Since drilling and electroplating have been completed before all layers are rolled together, this technique violates the traditional manufacturing process from the beginning. The innermost two layers are composed of traditional double boards, while the outer layers are different. They are composed of independent single boards. Before rolling, the inner substrate will be drilled, plated through, pattern transferred, developed and etched. The outer layer to be drilled is the signal layer, which is plated in such a way that a balanced copper ring is formed on the inner edge of the through hole. The layers are then rolled together to form a multi-substrate, which can be interconnected (between components) using wave soldering.Rolling may be done in a hydraulic press or in an overpressure tank (autoclave). In a hydraulic press, the prepared material (for pressure stacking) is placed under cold or preheated pressure (high glass transition temperature material is placed at a temperature of 170-180°C). The glass transition temperature is the temperature at which the amorphous region of an amorphous polymer (resin) or part of a crystalline polymer changes from a hard, rather brittle state to a viscous, rubbery state.The use of multiple substrates is in professional electronic equipment (computers, military equipment), especially when the weight and volume are overloaded. However, this can only be achieved by increasing the cost of multiple substrates in exchange for increased space and weight reduction. In high-speed circuits, multiple substrates are also very useful, they can provide designers of printed circuit boards with more than two layers of board surface to lay wires, and provide a large ground and power supply area.
PCB Glossary ⋅ 03/11/2021 14:13
single sided pcb
The single-sided pcb board is on the most basic PCB, the parts are concentrated on the one side, and the wires are concentrated on the other side. Because the board only appears on one of the sides, we call this PCB as single-sided pcb. Because the single-sided pcb has many strict restrictions on the design circuit (because there is only one side, the wiring between can not cross and must be around a separate path), so only early circuits use this type of board;The wiring diagram of the single sided board is mainly screen printing (screen printing), that is, the resist is printed on the copper surface, after etching, mark the solder resist, and finally the part guide hole and shape of part are completed by punching.In addition, some small-scale and diversified products use photoresist to form a pattern.What is single-sided board.single-sided circuit board, which is widely used in the assembly system of core components of various electronic equipment and is an indispensable part of normal operation of electronic equipment. Its importance is equivalent to the foundation of a building. Only with a single panel with excellent performance can we make better electronic products on this basis. It can be seen from the radio to the LCD TV internal structure. For non-professional friends, you may not know much about single-sided board materials. Don't worry, today I will give you a general knowledge about the single panel, including the material and characteristics of the single-sided board. History of single-sided boardFrom 1953 to 1955, Japan used imported copper foil to make phenolic cellulose paper copper -clad laminates for the first time, which were widely used in radios. In 1956, after the appearance of professional Japanese circuit board manufacturers, the manufacturing technology of single-sided boards rapidly progressed. In terms of materials,phenolic cellulose paper copper -clad laminates were mainly used in the early days. However, due to factors such as low electrical insulation, poor soldering heat resistance, and twisting at the time, materials such as epoxide cellulose paper copper-clad laminates and epoxide woven glass fabric copper-clad laminates have development, the current single-sided board required for consumer electronic equipment, almost using phenolic cellulose paper copper -clad laminates.Single panel features Material of single-sided boardThe single-sided printed circuit board is a product developed in the early 1950s with the emergence of transistors, focusing on the United States. At that time, the main production method was the direct etching method of copper foil as the mainstream.
PCB Glossary ⋅ 03/11/2021 11:11
PCBs can be single-sided (one layer of copper), double-sided (two layers of copper on both sides of one substrate layer), or multi-layer (inner and outer layers of copper, alternating with layers of substrate). Following is the list of available PCBs in the market. You can choose any PCB based on your requirements related to project.Single-Sided PCBs: It is made of a single layer of substrate or base material. Its one side is coated with a layer of metal, which is usually copper as it is an excellent conductor of electricity. The metal coating is coated with a protective solder, which is also covered by silk-screen to mark out all of the elements on the board. These PCBs are easy to design and manufacture as their circuits and components are soldered onto one side.Double-layer PCBs: Double-layer or double-sided PCBs have a base material with a thin layer of conductive metal, like copper, applied to both sides of the board. Holes drilled through the board allow circuits on one side of the board to connect to circuits on the other. Double-sided PCBs are typically used in applications which require an intermediate level of circuit complexity, such as Industrial controls, Power supplies, Instrumentation, HVAC systems, LED lighting, Automotive dashboards, Amplifiers and Vending machines.Multilayer PCBs: They are made of several layers of substrate boards which are separated by insulating materials. They come in different sizes as small as four layers or as large as ten or twelve layers. Multi-layer PCBs are suitable for using in File servers, Data Storage, Satellite systems, GPS technology, Weather analysis, and Medical equipment. Just like double-sided boards, the components on multilayer boards are connected through holes or vias on the board.Rigid PCBs: Rigid PCBs are printed circuit boards that are made out of a solid substrate material that prevents the board from twisting. Possibly the most common example of a rigid PCB is a computer motherboard. The motherboard is a multilayer PCB designed to allocate electricity from the power supply while simultaneously allowing communication between all of the many parts of the computer, such as CPU, GPU and RAM.Flex PCBs: They are made of a flexible substrate, typically a flexible plastic. The flexible material permits the board to fit into forms without affecting the circuits on the printed circuit board. These boards can restore heavy or bulky wiring in superior gear like satellites, where weight and space matter. Flex boards can also come in three formats: single-sided, double-sided or multilayer formats.Flex-rigid PCBs: Flex-rigid PCBs combine the best of both worlds when it comes to the two most important overarching types of PCB boards. Flex-rigid boards consist of multiple layers of flexible PCBs attached to a number of rigid PCB layers.Required components are connected electrically with the PCB board using two different method named as through hole technology and surface mount technology.
PCB Glossary ⋅ 03/11/2021 11:08
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