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RF PCB Printed Board
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  • Why does the PCB surface blisters? How to deal with it?
    Why does the PCB surface blisters? How to deal with it?
    • January 11, 2022

    Why does the PCB surface blisters? How to deal with it? The blistering of the circuit board surface is actually a problem of poor bonding force of the board surface, and then it is the surface quality problem of the board surface, which contains two aspects: 1. The cleanliness of the board surface; 2. The problem of surface micro-roughness (or surface energy). The blistering problem on all circuit boards can be summarized as the above-mentioned reasons. The bonding force between the coatings is poor or too low, and it is difficult to resist the coating stress, mechanical stress and thermal stress generated in the production process during the subsequent production process and assembly process, which will eventually cause different degrees of separation between the coatings. Some factors that may cause poor board quality in the production and processing process are summarized as follows: 1. The problem of substrate processing: Especially for some thinner substrates (generally below 0.8mm), it is not suitable to use a brushing machine to brush the plate because of the poor rigidity of the substrate. This may not be able to effectively remove the protective layer specially treated to prevent the oxidation of the copper foil on the board surface during the production and processing of the substrate. Although the layer is thin and the brush is easier to remove, it is difficult to use chemical treatment, so in the production process It is important to pay attention to control during processing, so as to avoid the problem of blistering on the board caused by the poor bonding between the substrate copper foil and chemical copper; this problem will also cause blackening and browning when the thin inner layer is blackened. Poor, uneven color, partial black browning and other problems. 2. The phenomenon of poor surface treatment caused by oil stains or other liquids contaminated with dust during the machining (drilling, lamination, milling, etc.) process of the board surface. 3. Poor sinking copper brush plate: The pressure on the front grinding plate of the sinking copper is too high, causing the orifice to be deformed, brushing out the copper foil rounded corners of the orifice or even leaking the base material, which will cause the orifice to bubble during the process of electroplating and tinning welding of the sinking copper; even if it is brushed The board does not cause leakage of the substrate, but the heavy brushing board will increase the roughness of the hole copper, so during the process of microetching roughening, the copper foil at this place is very easy to produce excessive roughening phenomenon, and there will also be a certain quality. Hidden hazards; therefore, attention should be paid to strengthening the control of the brushing process, and the brushing process parameters can be adjusted to the best through the wear scar test and the water film test; 4. Washing problem: Because the electroplating treatment of copper sinking has to go th...

  • PCB Better Times, Worthy of Better You
    PCB Better Times, Worthy of Better You
    • January 01, 2022

    PCB Better Times, Worthy of Better You Time flies, and the year sequence is updated. Turning the sand to the candlelight, 2021 has quietly gone far. Looking back at 2021, difficulties and striving will coexist; looking forward to 2022, challenges and hopes will be together! On this special day, Bicheng pays tribute to every PCB person who struggles! We wish you all the best in the new year and achieve better results! The time sequence is changed, and all the waves of 2021 will be put on the echo wall of historical evolution. The first ray of sunshine of the new year is about to illuminate the face of every one of us struggling. This is exactly what the brand new 2022 looks like... At this moment, standing at the meeting point of resigning the old and welcoming the new, in 2021, we ushered in the Chinese "astronauts" soaring in the universe, ushered in the green waters and green mountains of the first year of "Double Carbon", ushered in The Communist Party of China has its centenary birthday, but we also ushered in the heavy rains in the Central Plains and the help of the epidemic under the raging epidemic... Yes, the great changes unseen in a century are accelerating, and our company has also experienced a magnificent and ups and downs year. It is worth celebrating that we have always adhered to the strategy of "one yuan, consolidating costs, and diversification". We have not only deeply cultivated the PCB supply chain, but also dared to break new tracks. Both the grand blueprint and the current actual results are absolutely politically correct. . In the past year, our company has continued to work hard in the field of PCB materials, based on R&D and innovation, maintaining technology leadership, strengthening technology iterations, and developing and optimizing many mature technologies including hole filling electroplating, pulse electroplating, metal bonding agent, etc. High-end new products continue to create more value for the company and the industry. It is also because of our deep understanding of PCB chemical materials that our equipment has more bright spots than peers in terms of energy saving, stable operation and humanized operation. This kind of overall solution that takes into account the combination of medicine and equipment The program has won the recognition of customers. In the mid-winter season, I look forward to spring most. Difficulties and hard work coexist in 2021, challenges and hopes in 2022, I believe we will more calmly cope with the changes and opportunities unseen in a century, and move forward with the "craftsman spirit" to achieve stability in parallel. The future is here. Facing the magnificent journey of the new era, we don’t want to be fantasised, we don’t lie in vain, we are born at the right time, destined to be calm and destined to burn youth with the pulsation of the times. Better times, worthy of better you! A tribute to the struggling Stande people! Salute to everyone on the road of struggle! Happy New Y...

  • 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...

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