A printed circuit board (PCB) mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from copper sheets laminated onto a non-conductive substrate. PCB's can be single sided (one copper layer), double sided (two copper layers) or multi-layer. Conductor on different layers are connected with plated-through holes called vias. Advanced PCB's may contain components - capacitors, resistors or active devices - embedded in the substrate.
Introduction
The flexible circuit board is also called the "soft", is a made of polyimide or polyester film as the backing material with high reliability, excellent flexible printed circuit board. Flexible circuit provides excellent performance and can meet the installation design needs to be smaller and higher density, also helps to reduce the assembly process and enhance reliability. The flexible circuit board is to meet the requirements of miniaturization of electronic products and mobile, the only solution. Free bending, coiling, folding, can withstand the dynamic bending millions of times without damage to the wire, can be arbitrarily arranged in accordance with the spatial layout requirements, and moving in three-dimensional space and scale, so as to achieve integration of the components assembly and wire connection; The flexible circuit board can greatly reduce the volume and weight of the electronic products, electronic products to high density, miniaturization, high reliability and the needs of the development of direction. With the high density of wiring, the characteristics of light weight, thin thickness.
Flexible Circuit Board (Flexible printed circuit board) hereinafter referred to as "soft Board", commonly known as FPC industry, and is made of Flexible insulating base material made of polyimide or polyester film (mainly) Printed Circuit boards, [1] has a number of advantages of rigid Printed Circuit Board does not have. For example, it can free bending, coiling, folding. Using FPC can greatly reduce the volume of electronic products, applicable to electronic products to the needs of the development of high density, miniaturization, high reliability direction. Therefore, FPC in aerospace, military, mobile communication, portable computers, computer peripherals, PDA, digital cameras, and other fields or the product has been widely used.
FPC has good heat resistance and weldability, and is easy to install and low comprehensive cost.
The flexible printed circuit board can be single side, double side and multilayer. Adopted by the base material is given priority to with polyimide copper clad. This kind of material high heat resistance and good dimensional stability, and both mechanical protection and good electrical insulation performance of the cladding by suppressing and into the final product. Double side, multi-layer printed circuit board surface and inner conductor through the electrical connection in the metallization for inner and outer layer circuit.The Function of flexible Circuit board can be divided into four kinds, respectively guide lines (Lead Line), Printed Circuit (Printed Circuit), Connector, Connector and multi-functional integrated system (Integration of Function), application covers computer, computer peripheral auxiliary system, consumer minsheng electronics and automobile, etc.
The flexible printed circuit board can be single side, double side and multilayer. Adopted by the base material is given priority to with polyimide copper clad. This kind of material high heat resistance and good dimensional stability, and both mechanical protection and good electrical insulation performance of the cladding by suppressing and into the final product. Double side, multi-layer printed circuit board surface and inner conductor through the electrical connection in the metallization for inner and outer layer circuit.The Function of flexible Circuit board can be divided into four kinds, respectively guide lines (Lead Line), Printed Circuit (Printed Circuit), Connector, Connector and multi-functional integrated system (Integration of Function), application covers computer, computer peripheral auxiliary system, consumer minsheng electronics and automobile, etc.
Category
1, single panel
Using single PI fu copper material in line is completed, then covered a layer of protective film, forming a kind of only a single conductor flexible circuit board.
2, ordinary double panel
Using double PI plate coated copper material in double circuit, after the completion of two sides respectively, coupled with a layer of protective film, become a kind of circuit board with double conductors.
3, the substrate to generate single panel
Using pure copper foil material in circuit process, respectively on the two sides each add a layer of protective film, successively in become a kind of only a single conductor but in double-sided circuit boards, there is the conductor of the circuit board.
4, substrate to generate double panel
Using two layers of single PI fu copper materials supplemented by a window in a particular location among bonding adhesive for bonding, as in the local area, local area separation of two layers of structure of double conductor circuit boards in order to achieve the delamination area with high flexural performance of the circuit board.
classification
In other countries, has been widely used soft PCB in the early sixties . Country , then in the sixties began production applications. In recent years , as the global economic integration and open the city to try to introduce technology to promote their usage constantly growing, some small and medium -rigid PCB Factory targeting this opportunity to make use of soft hardware technology, the use of existing tools and tooling equipment technology for improvement, restructuring production of soft PCB and flexible PCB dosage adaptation growing needs . To further understanding of PCB, PCB here on soft classification are introduced.
Flexible PCB usually classified according to the following conductor layers and structures :
1 soft -sided PCB
Soft -sided PCB, only the conductor layer , the surface layer or covering can not cover. The insulating base material used , different applications with different products . Commonly used insulating materials are polyester , polyimide, polytetrafluoroethylene, soft epoxy - glass cloth.
2 soft -sided PCB
Soft -sided PCB, there are two conductors. Such soft -sided PCB applications and soft -sided PCB with the same advantages , its main advantage is increased wiring density per unit area. It may be there , and there are no metal holes without covering layer is divided into :
. a non- metallized holes, no cover layer ;
. b non- metallized holes covering layer ;
. c metallized holes, no cover layer ;
d. metallized holes with a covering layer.
Soft -sided PCB without overlay rarely used.
3 multilayer flexible PCB
Multilayer PCB as soft as rigid multilayer PCB , multilayer lamination technology , can be made flexible multilayer PCB. The simplest multilayer soft -sided PCB on both sides of the PCB is covered with two layers of copper shield and the formation of three soft PCB. This three-layer flexible PCB or equivalent coaxial conductor shielded wire on the electrical characteristics. The most common structure is a four-layer PCB multilayer flexible structure, with inter- layer metal interconnection holes to achieve the intermediate floor is generally the power source layer and the ground layer .
Advantages of the multi-layer flexible PCB substrate film is lightweight, and has excellent electrical characteristics , such as low dielectric constant. Multilayer flexible PCB board as a base film made of polyimide , the weight ratio of the rigid multi-layer epoxy glass board PCB light about 1/ 3, but it lost sided, double-sided flexible PCB excellent the flexible , most of these products are not required can be flexible.
Advantages and disadvantages
1. Advantages:
(1) free bending, coiling, folding, can be arbitrarily arranged in accordance with the spatial layout requirements, and is moving in three-dimensional space and scale, so as to achieve integration of the components assembly and wire connection;
(2) use of FPC can greatly reduce the volume and weight of the electronic products;
(3) the FPC has good heat resistance and weldability, and is easy to install and low comprehensive cost, a combination of hard and soft design also to some extent compensate for the flexible base on component bearing capacity of slightly less than.
Assembly density, small volume, light quality, because of the high density assembly, connection between components (including parts) is reduced, thus increasing the reliability; Can increase the connection layer, and increase flexibility design; Can also constitute the impedance of the circuit, can form a certain high-speed transmission circuit, can be set circuit, electromagnetic shielding layer, still can install metal core layer meet the demand of special function such as thermal insulation and; Easy installation, high reliability.
2. Disadvantages:
(1) one-time initial cost is high
Due to soft PCB is designed for special applications, manufacturing, so start circuit design, wiring and photoplate needs higher cost. Unless there is special need to apply the soft PCB, usually a small application, had better not use.
(2) soft PCB change and it is difficult to repair
Once made from soft PCB, we must to change from the reproduction or light painting program, so it is not easy to change. Its surface covered a layer of protective film, to remove before repair, repair after recovery, this is a difficult job.
(3) the size limitation
Soft PCB in it is not case, usually made by the intermittent method process, so be restrictions on the size of production equipment, can't be very long, very wide.
(4) the improper operation is easy to damage
Pack the improper operation may cause the damage of the soft circuit, the soldering and rework operation need to be trained personnel.
High cost, long cycle; Need high reliability testing method. Multilayer printed circuit electronic technology, multi-function, high speed, small volume product direction of large capacity. With the development of electronic technology, especially the mass and the wide application of very large scale integrated circuit, high density of multilayer printed circuit on the number of fast, high precision, high change direction appear fine lines.
Characteristics
1, short: assembly time is short
All line configuration is complete. Save extra wiring connection work.
2, This small: small volume PCB
Can effectively reduce the products volume. The increase is to carry on the convenience.
3. Light: weight lighter than PCB (hard)
Can reduce the weight of the final product.
4, Thin: thinner than PCB thickness
Can improve the softness. Strengthen then limited space for three dimensional assembly.
Visiting card
Flexible circuit board has save space, reduce weight and flexibility of higher merits, the global demand for the flexible circuit board is increasing year by year. Flexible circuit board's unique characteristics make it in a variety of occasions to become rigid circuit board and alternative ways of traditional wiring plan, it also promote the development of many new areas, is the fastest growing part of the computer hard disk drive (HDD) internal cables, growth in second place is new type of integrated circuit encapsulation, flexible circuit technology in portable devices such as mobile phone market potential is very great.
Prenatal treatment
Make a fine texture of FPC board must have a complete and reasonable production process, from the production before the pretreatment to the last shipment, every process must be rigorous execution. In the process of production, in order to prevent short circuit caused by the excessive low yield or reduce drilling, rolling and cutting process problems caused by the FPC board scrap, feeding problems, and assess how to use the best material to meet customer effect of the flexible circuit board. Prenatal preprocessing is especially important.
Prenatal pretreatment, need to deal with three aspects, these three aspects is done by the engineer. First is the FPC board project evaluation, main is to assess the client's FPC board whether can production, the company's production capacity can meet the requirements of the customer's system board and unit cost; If engineering through evaluation, and then need to prepare material immediately, to meet the production of raw materials supply, finally, engineers to: customer engineeringdocuments, such as CAD diagram, gerber line data processing, in order to suit the production environment of production equipment and production specifications, then the production drawings and MI (engineering process card), and other materials to the production and control, purchasing and other departments, into the regular production process.
Production process
Double panel
cuttingdrillingPTHelectroplatingBefore processingStick a dry filmparaexposuredevelopingGraphics electroplatingTake off the filmBefore processingStick a dry filmPara lightdevelopingetchingTake off the filmSurface treatmentStick a covering filmTo suppresscuringHeavy nickel goldPrinted charactersshearElectrical measuringDie cuttingFinal inspectionpackagingshipment
Single panel
cuttingdrillingStick a dry filmparaexposuredevelopingetchingTake off the filmSurface treatmentStick a covering filmTo suppresscuringSurface treatmentHeavy nickel goldPrinted charactersshearElectrical measuringDie cuttingFinal inspectionpackagingshipment
Manufacturing technique
Surface treatment: zedoary, anti-oxidation, gold plated, spray tin
Appearance: hand shape, CNC (CNC) cutting, laser cutting
Copper base material thickness, 1/3, 1/2 ounce, 1 oz, 2 oz, 4 ounces
Detector
According to the characteristics of the flexible circuit board materials and widely used in the field, in order to more effectively save the volume and reach a certain accuracy, makes the characteristics of three dimensional and the thickness of the thin better application in the digital products, mobile phones and laptops. Flexible printed circuit board (FPC) testing instruments used for optical image measuring instrument.
Application and use
Flexible connection parts of the circuit board is mainly used in electronic products, such as mobile phone line, LCD module and so on, compared with hard board, its smaller volume, lighter weight, can realize the bending deflection, stereoscopic 3 d assembly and other advantages. Generally most of the soft board to stick components.
The mobile phone
Focuses on the flexible circuit board light weight and thin thickness. Can effectively save the product volume, and the connection of the battery easily, microphone, and buttons and become an organic whole.
Computers and LCD screen
Use of flexible circuit board integrated circuit configuration, and thin thickness. The digital signals into pictures, through the LCD screen.
CD player
Focus on three dimensional assembly characteristics of flexible circuit board and the thickness of thin. Will be huge CD to carry around
Disk drives
Hard disk or diskette, is very dependent on FPC high softness and thickness of the 0.1 mm slim, finish quickly read. Whether it be a PC or NOTEBOOK.
The latest use
Hard disk drive (HDD, hard disk drive) of suspended circuit (Su ensi. N cireuit) and the components of xe packaging board, etc.
Wireless charging coil array, the electromagnetic concentration in a certain area, cut down the consumption of space transfer, and thus improve the power conversion efficiency.
Basic structure
Copper foil substrate (Copper Film)
Copper foil: basic into two kinds of electrolytic copper and rolled copper. Common to 1 oz 1/2 oz on thickness and 1/3 oz
The thickness of the substrate film: common has two kinds of 1 mil and 1/2 mil.
Thickness of glue (agents) : according to customer's requirement.
Covering Film protective Film (Cover Film)
Covering membrane protective film: surface insulation. The thickness of the common have 1 1/2 mil mil and.
Thickness of glue (agents) : according to customer's requirement.
The debonding paper: avoid then agent before the pressure from foreign body; Easy operation.
Reinforcement plate (PI Stiffener Film)
Reinforcement plate: reinforcing FPC mechanical strength, convenient surface live-fire homework. The thickness of the common three mil mil to 9.
Thickness of glue (agents) : according to customer's requirement.
The debonding paper: avoid agents in front of the pressure from foreign bodies.
According to the conductive copper foil layer division, is divided into single layer board, laminated panel, double panel, double plate, etc. Single layer plate structure: the structure of the flexible plate is the simplest structure of flexible plate. Base material + cellophane tape, copper foil is usually bought a set of raw materials, protective film + cellophane tape is another way to buy raw materials. First of all, the copper foil for etching process to get need circuit, such as drilling in protective film to show the corresponding welding plate. After cleaning with a rolling method to combine the two. Then the welding plate showing in part of electric plating or tin, for their own protection. So, big board is ready. General stamping into corresponding in the shape of a small circuit board. There are directly without the protective film on the copper foil seal resistance welding layer, so the cost would be lower, but the circuit board mechanical strength will become poor. Unless the strength requirement is not high
but need to try to lower price, it is best to stick the protective film method. Double layer plate structure: when circuit circuit is too complex, single board to wiring or in need of copper foil for earth shield, will need to use double plate even sandwich plate. Sandwich plate with single layer plate is the most typical difference increases the pore structure in order to link the layers of copper foil. General substrate + cellophane tape, copper foil first processing technology is made. On the base material and copper foil drilling first, after cleaning must be the thickness of the copper plating, a hole is ready. After the production process and almost the same as on the single. Double panel structure: pair bonding pad, the two sides of the panel is mainly used for connection and other circuit board. Although it and single layer plate structure is similar, but technology difference is very big. Its raw materials are copper foil, protective film + cellophane tape. First according to the requirements of welding plate location hole in the protective film, the copper foil again, corrosion of welding plate and fuses with another good drill hole after the protective film.
FPC patch points
FPC surface of SMT process requirement and the traditional hard board PCB SMT solution has many differences, if you want to do a good job in FPC SMT process, the most important thing is to locate. Hardness is not enough, because FPC board is soft, if you don't use special load board, cannot complete fixed and transmission, also won't be able to complete printing, SMT, basic SMT process such as a furnace.
Economy
If the circuit design is relatively simple, total volume is not large, and space is appropriate, even within the traditional way is a lot cheaper. If the line is complex, with many signals or have special electrical or mechanical performance requirements, flexible circuits is a better design options. When the size and performance of the application beyond the ability of rigid, flexible assembly is the most economical way. On a thin film can be made with 5 12 mil mil hole welding plate and 3 mil line and spacing of flexible circuits. Therefore, in the SMT chip directly on thin film is more reliable. Because do not contain ions may be drill WuYuan flame retardants. These may have a protective film and curing under high temperature, high glass transition temperature. Flexible material compared with the rigid material cost saving reason is exempt from the connector.
Development prospect
Based on FPC broad market in China, Japan, the United States, Taiwan, countries and regions of large enterprises have been set up in China. By 2012, flexible circuit board and rigid circuit board, has achieved great development. However, if a new product according to the "start, development, climax, decline - out" rules, FPC is in the area between the climax and decline, in the absence of a product can take the place of the flexible plate, flexible plate will continue to build market share, it is necessary to innovation, only innovation can get out of this circle.
So, FPC future from what respect to innovation? Mainly in four aspects:
1, the thickness. FPC thickness must be more flexible, must be thinner;
2, the folding resistance. Can bend is FPC inherent features, the future of FPC folding resistance must be more strong, must be more than 10000 times, of course, this requires a better base material;
3, price. At present, the price of FPC PCB is much higher, if the FPC prices down, the market is broad will be many.
4, craft level. In order to meet the various requirements, FPC technology must be upgraded, the smallest aperture, minimum line width/line spacing must meet higher requirements.
Therefore, from the four aspects of FPC in innovation, development and upgrade, can let it in second life!
Flexible circuits industry is in a small but rapidly development. Polymer thick film method is a kind of high efficiency and low cost of the production process. The process on the cheap, flexible substrate, conducting polymers selective ground screen printing ink. The representative of the flexible substrate for PET. Polymer thick film conductor method includes screen printing metal filler or carbon powder filler. Polymer thick film method itself is very clean, the use of lead-free, SMT adhesives without etching. Because of its use addition process and base material of low cost, polymer thick film circuit is 1/10 of the price of copper polyimide film circuit; Rigid circuit board price is 1/2 ~ 1/3. Polymer thick film method is especially applicable to the equipment control panel. On mobile phones and other portable products, polymer thick film method is suitable for the components on the printed circuit board, switch and lighting devices into polymer thick film circuit. Both save costs and reduce energy consumption.
In the next few years, smaller, more complex and assembly cost higher flexible circuits will require more novel approach to assemble, and to increase the mixed flexible circuits. For flexible circuits industry challenge is to use the technical advantages, keep with the computer, telecommunication, consumer demand and market of active sync. In addition, the flexible circuits will play an important role in utilizing action.
flexible PCB technology
A flexible (Flexible Printed circuit board) is a polyimide or polyester film as a base material having a high reliability , excellent flexible printed circuit . Early flexible PCB is limited to the car dashboard and laptop computers and other sophisticated specialized equipment . And now flexible PCB has been applied in the cellular phone , PDA, MP3/MP4 players, portable CD players , home VCD / DVD, mobile phones and cell phones, digital cameras, medical and other space-constrained telecom and consumer electronics products increasingly common.
We can according to your specific requirements tailored for you , but also batch processing. Can you provide a single layer board , double board, plywood , two panels. Because of the flexible board is mainly used for bending the occasion requires , if the design or process is unreasonable , prone to micro-cracks , open welding defects . Therefore, we strictly observe the following procedures to ensure high effectiveness of our services , fast, reduce rework , saving you valuable time.
During single- board , we will first deal with the copper foil etching and other processes to get the circuit need to be drilled protective film to expose the corresponding pad , after cleaning and then rolling method to combine the two . Then the exposed pad part or tin, gold plating protection . Usually also punched into the corresponding shape of a small circuit board. A protective film is also not directly in the solder resist layer is printed on the foil , so that the cost will be lower , but the mechanical strength of the circuit board deteriorates . So, we usually apply the protective film paste method .
When the line is too complex circuits , single board can not require wiring or copper for grounding the shield , the board will need to use double or even plywood .
The most typical is the difference between multilayer and single board structure in order to increase the through-hole link layers of copper foil . The first substrate and the copper foil in the borehole , after cleaning a certain thickness of copper plating , a few holes.
Both sides of the dual panel has pads , and is mainly used to connect to other circuit boards . Although it is similar and single board structure, but the production process varies greatly. Must first press the pad position requires drilling protective film , foil and then paste , etched and then paste pads and lead to better protection film another drill hole .
Flexible circuit board
Because of the advantages (for example, cost, space, and weight savings) that flexible and Rigid-Flex-circuit boards have for some projects, they are used ever more frequently. Multi CB can produce your flexible circuit boards with the highest quality, either as prototypes or in series.
The standard surface used is immersion gold, the contours are formed according to requirements, preferably using laser cutting, or also with mechanical milling.
You should discuss the selected materials and design for the construction and layout of flexible circuit boards with us in the planning phase; we can assist you to work out the optimum solution!
Technical options for flexible circuit boards
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