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RF PCB Printed Board
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  • What is Stripline and microstrip line in PCB? Tag# RT/duroid 5880 Tag# Rogers 5870
    What is Stripline and microstrip line in PCB? Tag# RT/duroid 5880 Tag# Rogers 5870
    • May 07, 2009

    Rogers RT/duroid 5870 and 5880 glass microfiber reinforced PTFE composites are designed for exacting stripline and microstrip circuit applications. Today we’re learning what stripline and microstrip line are. Stripline: a banded line that walks in the inner layer and is buried inside the PCB, as shown below The brown part is the conductor, the green part is the PCB insulating dielectric, stripline is the ribbon wire embedded between the two layers of conductors. Because stripline is embedded between two layers of conductors, its electric field distribution is between two conductors (planes) that wrap it, and does not radiate energy or be disturbed by external radiation. but because it is all surrounded by dielectric (dielectric constant is larger than 1), the signal is transmitted slower in stripline than in microstrip line! Microstrip line: a strip line attached to the surface of a PCB layer, as shown below The brown part is the conductor, the green part is the PCB insulating dielectric, and the brown block above is the microstrip line. The light green part is epoxy organic material. Since one side of the microstrip line is exposed to the air (which can form radiation around or be disturbed by radiation around it), and the other side is attached to the PCB insulating dielectric, the electric field formed by it is distributed in the air. The other part is distributed in PCB insulating medium. Its outstanding advantage is that the signal transmission speed in the microstrip line is faster than that in the stripline. Conclusion 1. Microstrip line is a banded wire (signal line) separated from the ground plane with a dielectric. If the thickness, width, and distance between the line and the ground plane are controllable, its characteristic impedance is also controllable. 2. Stripline is a copper strip line placed in the middle of the dielectric between two layers of conductive plane. If the thickness and width of the line, the dielectric constant of the medium and the distance between the two conductive planes are controllable, then the characteristic impedance of the line is also controllable. Impedance calculation of microstrip and Striplines: a. microstrip line Z ={87/[ sqrt (Er+ 1.41)]} ln [5.98 H/(0.8 W+T)] Among them, the W is the line width, the T is the copper thickness of the line, the H is the distance from the line to the reference plane, and the Er is the dielectric constant of the PCB plate material. This formula must be applied at 0.1<(W/H)<2.0 and 1<(Er) to 15. b. stripline Z =[60/ sqrt (Er)] ln {4H/[0.67π(T +0.8W)]} Among them, the H is the distance between the two reference planes, and the line is located in the middle of the two reference planes. This formula must be applied in W/H<0.35 and T/H<0.25.

  • Top 10 Unacceptable Quality Problems of Printed Circuit Board
    Top 10 Unacceptable Quality Problems of Printed Circuit Board
    • August 17, 2010

    There are many control points in the whole production process, the board will be broken if there is a little bit of carelessness, the quality problems of PCB are emerging endlessly, this is also a headache to people, because if only one piece has a problem, then most of the devices will also cannot be used. In addition to the above problems, there are also some problems with high potential risks, we have compiled a total of top ten problems, listed here and with some handling experience to share with you 1.【Delamination】 Delamination is a long-standing problem of PCB, steadily ranking the first of the common problems. The causes may be as follows: (1) It is improperly packaged or stored, or affected with damp; (2) Too long time of storage, which exceeds the storage period, PCB board is affected with damp; (3) The supplier’s material or process problems; (4) Poor material selection of design and poor distribution of copper surface. The problem of being affected with damp is easy to happen, Even if you choose a good package, and there is a constant temperature and humidity warehouse, but the transportation and temporary storage process cannot be controlled. But being affected with damp can still be solved, vacuum conductive bags or aluminum foil bags can be a good protection against moisture intrusion, at the same time, it is required to put a humidity indicating card in the packaging bags. If the humidity indicating card is found to exceed the standard before use, it can be solved by baking before putting online, the baking condition is usually 120 degrees, 4H. Common possible causes may include: poor black oxidation, PP or inner board is affected with damp, insufficient PP glue quantity, abnormal pressing, etc.. In order to reduce this kind of problems, special attention should be paid to the management of PCB suppliers to the corresponding processes and reliability tests of delamination. Taking the thermal stress test in the reliability test as an example, the requirement of pass standard of a good factory is no delamination of over 5 times, and confirmation will be conducted in each period of the sample stage and the mass production. However, the pass standard of ordinary factory may only twice, and confirm only once every several months. The simulation mounting IR test can also prevent more outgoing of defective products, which is an essential for an excellent PCB factory. Of course, the PCB design of the design company itself can also bring hidden dangers of delamination. For example, there is often no requirement of the choice of plate Tg, the temperature resistance of ordinary Tg material will be relatively poor. In the era of lead-free becoming a mainstream, the selection of Tg above 145°C is relatively safe. In addition, the open large copper surface and too dense buried via area is also the hidden dangers of PCB separated layer, which need to be avoided in the design. 2.【Poor solderability】 Solderability is also one of the serious proble...

  • How to specify a PCB?
    How to specify a PCB?
    • October 23, 2011

    A PCB user generally needs to present all of the primary manufacturing data in a complete and unambiguous way that the PCB manufacturer can quote and produce the boards without error. A checklist is listed as follows. Some parameters not necessary for a particular job can be deleted so that the specification form only reflects the relevant data. (1)Company name (2)Part number (3)Lot size and annual requirements (4)Layer count (5)Board size (6)Board thickness (7)Board shape (8)Panelization (9)Board build-up (10)Boards with controlled impedance (11)Test coupon (12)Machining (Contouring) (13)Laminate type and UL flammability (14)Warp & Twist (15)Outer layers (16)Inner layers (17)Solderability preservation (18)Solder masks (19)Notation (20)Peelable solder mask (21)Carbon printing (22)Plated through holes (PTHs) (23)Non-PTHs (24)Milled Holes (Slots) (25) Blind via holes (26) Buried via holes (27)Board tooling holes (28)Panel tooling holes (29)Board mounting (30)Edge connectors (31)Soldering conditions (32)Markings (33)Electrical test (34)Automatic optical inspection (35)Minimum pattern conditions (36)Quality conditions A view of PCB panelization To know a basic situation of one PCB, these 7 points have to be taken into consideration: (1) Laminate type (base material) (2) Layer count (3) Board size (4) Board thickness (5) Copper weight (6) The color of solder mask and silkscreen (7) Surface finish Is it much simple now? If you have any enquiries, please feel free to contact us. Welcome your patronage.

  • Flexible Printed Circuit Board
    Flexible Printed Circuit Board
    • September 26, 2021

    1, Purpose of Flexible Circuits     ◆to provide interconnections between printed circuit boards and other components.     ◆to serve as three-dimensional substrates for the mounting of SMT components, e.g. in mobile phone, digital camera and video cameras etc.     ◆to establish interconnections capable of withstanding dynamic flexing.     ◆to form part of flex-rigid circuit boards. 2, Basic Types of Flexible Circuit ◆ Single-Sided Flexible Circuits This is the simplest type, and consists of a thin and flexible base material to which a copper foil is laminated by means of an adhesive. The finished circuit is frequently provided with a coverlay bonded to the copper side by means of an adhesive. Holes for components or connector pins are drilled or punched in the flexible circuit to provide non-plated-through holes. Holes in the coverlay are drilled or punched before bonding the coverlay to the flexible circuit. ◆  Double-Sided Flexible Circuits As the name suggests, the circuit consists of a thin and flexible base material with copper foil laminated to each side. The outer sides of the finished circuits are frequently provided with coverlays bonded to the outer sides (copper). Plated-through holes in double-sided flexible circuits are usually drilled, instead of punched. Usually the flexible circuits are provided with a coverlays on both sides ◆  Multilayer Flexible Circuits A multilayer flexible circuit consists of a number of thin and flexible base laminates and copper foils laminated together by means of adhesive, in very much the same way as rigid multilayer boards. Also it is common practice to bond coverlays to the outer sides (copper). Plated-through holes can be provided in virtually the same way as in double-sided flexible circuits. ◆  Flex-Rigid Circuits A flex-rigid circuit is a combination of rigid boards and flexible circuits, the latter creating flexible inter-connects between the rigid boards to which they are laminated by means of bond plies. The flexible circuit is manufactured separately and bonded to the rigid boards, either symmetrically, i.e., in the middle of the rigid boards, or asymmetrically, i.e., to the outer side of the rigid boards to be interconnected. Plated-through holes are provided in the rigid sections of the flex-rigid circuits to establish electrical connection between the interconnect (the flexible circuit section) and the electronic circuits of the rigid boards. The processes are similar to those used when manufacturing rigid multilayer boards. ◆  Flexible Circuits with Rigid Areas In some cases, the flexible circuit must support a number of relatively heavy components or even a connector part. Therefore it is necessary to reinforce such an area. This is accomplished by bonding a stiffener to that area. The stiffener can be an extra layer of not too thin polyimide, or it can be a glass/epoxy laminate. The stiffener is provided with holes...

  • What is high Tg PCB?
    What is high Tg PCB?
    • June 13, 2012

    What is high Tg PCB? What are the advantages of using high PCB? Glass Transition Temperature (Tg) The thermal properties of the resin system are characterized by the glass transition temperature (Tg), which always is expressed in °C. The most commonly used property is the thermal expansion. When measuring the expansion versus the temperature, we can get a curve as shown in following picture. The Tg is determined by the intersection of the tangents of the flat and steep parts of the expansion curve. Below the glass transition temperature, the epoxy resin is rigid and glassy. When the glass transition temperature is exceeded, it changes to a soft and rubbery state. For the most commonly used types of epoxy resin (FR-4 grade), the glass transition temperature is in the range 115-130°C, so when the board is soldered, the glass transition temperature is easily exceeded. The board expands in the Z-axis direction and stresses the copper of the hole wall. The expansion of epoxy resin is about 15 to 20 times greater than that of copper when exceeding Tg. This implies a certain risk of wall cracking in plated-through holes, and the more resin around the hole wall, the greater risk. Below the glass transition temperature, the expansion ratio between epoxy and copper is only three times, so here the risk of cracking is negligible. As above stated, when the temperature of a high Tg PCB rises to a certain area, the substrate will be turned into "rubbery state" from “glassy state”, the temperature at this time is called the glass transition temperature (Tg) of the PCB board. That is, Tg is the maximum temperature (° C) at which the substrate remains rigid. In other words, the substrate materials of ordinary PCB not only be soften, deform, melt and so on at high temperatures, but also have a sharp decline in the mechanical and electrical properties (I do not think you are willing to see this happen to your products). The Tg of general board is above 130 celsius degrees, high Tg is generally greater than 170 celsius degrees, medium Tg is about greater than 150 celsius degrees. PCB boards with Tg ≥ 170 ° C are usually called high Tg PCBs. If the Tg of a substrate is increased, then the characteristics of heat resistance, moisture resistance, chemical resistance, and stability resistance etc., of the PCB will be improved and enhanced. The higher the Tg value, the better the temperature resistance of the board, especially in the lead-free process. High Tg is more widely used nowadays. High Tg refers to high heat resistance. With the rapid development of the electronics industry, especially the development of the electronic products represented by computers to the trend of high-functionality and high multilayered, higher heat resistance of the PCB substrate material is required as an important guarantee. The emergence and development of high-density package technology represented by SMT, CMT, makes the PCB more and more inseparable from the high heat resistance suppo...

  • Current Situation and Development Trend of the Circuit Board Industry
    Current Situation and Development Trend of the Circuit Board Industry
    • August 05, 2021

    [Industry news] Current Situation and Development Trend of the Circuit Board Industry Printed circuit board is the key interconnect for assembling electronic components, not only for electronic components to provide electrical connection, but also carries the functions of digital and analog signal transmission of electronic equipment, power supply and signal transmission and receiving of radio frequency microwave etc.. Vast majority of electronic equipment and products have to be equipped, so it is called "the mother of electronic products". In 2020, the 5G industry develops steadily, and 5G, AI, server equipment and automotive electronics have become an important growth point in the PCB industry. According to Prismark’s forecast in May 2021, The PCB industry has a projected growth rate of 14.0% in 2021 and will grow at a compound annual growth rate of 5.8% between 2020 and 2025, with global PCB output reaching $86.325 billion by 2025. The Industrial Development Trend of the Main Products (1) Communications electronics industry The communications electronics market mainly includes product categories such as mobile phones, base stations, routers and switches.The development of 5G promotes the rapid development of the communication and electronics industry. According to Prismark estimates, the global output value of PCB is $21.211 billion in 2021, and will grow at a compound annual growth rate of 6.3% between 2019 and 2024, with the output value reaching $27.836 billion in 2024, accounting for 33.8% of the global PCB industry total output. (2) Consumer electronics industry In recent years, AR(augmented reality), VR(virtual reality), tablet computers and wearable devices have frequently become hot spots in the consumer electronics industry. Combined with the general trend of global consumption upgrading, consumers have gradually moved from the previous material consumption to service-oriented and high-quality consumption.At present, the consumer electronics industry is brewing the next new blue ocean represented by AI, IoT, smart home. Innovative consumer electronics products emerge one after another and will penetrate all aspects of consumer life. Prismark estimates global PCB output in consumer electronics at $9.273 billion in 2021 and will grow at a compound annual growth rate of 4.2% between 2019 and 2024, reaching $11.44 billion in 2024, accounting for 13.9% of global PCB industry output. (3) Automotive electronics industry According to Prismark estimates, the global automotive electronics in 2021, PCB output value fell to $6.192 billion, but with the global automobile industry from the electronic into the intelligent era, driving the vehicle circuit board output value continues to rise, It still grew at a compound annual growth rate of 4.6% between 2019 and 2024, 2024 output value will reach $8.748 billion, accounting for 10.6% of the global PCB industry total output value. Organized from the public information

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