Mainly used in cell phones, laptops, PDAs, digital cameras, LCMs and many other products. [Edit] Flexible Printed Circuit Board (FPC) features - short, light and thin 1. Short: short assembly time
All lines are configured to complete. Eliminate redundant wiring connection work
2. Small: smaller than the PCB
can effectively reduce the size of the product. Increase portability
3. Lightweight: Lighter than PCB (hardboard)
Can reduce the weight of the final product
4. Thin: Thinner than PCB
Can improve flexibility. Enhance the limited space for three-dimensional assembly [Edit Paragraph] Flexible Circuit Board Product Applications Mobile Phones
Focusing on the light weight and thin thickness of flexible circuit boards. Flexible circuit boards allow you to efficiently save on product volume and easily connect the battery, microphone, and buttons into a single unit.
Computers and LCD screens
Utilizing the integrated circuit configuration of flexible circuit boards, as well as the thin thickness. The digital signal is converted into a picture and displayed on an LCD screen
CD Walkman
Focuses on the three-dimensional assembly characteristics of flexible circuit boards and their thin thickness. It turns a bulky CD into a portable companion
Disk drives
Whether it's a hard disk or a floppy disk, it relies heavily on the flexibility of FPCs and their ultra-thin thickness of 0.1mm to accomplish fast data readout. Whether it's a PC or a NOTEBOOK. [Edit Paragraph] Basic Structure of FPC Copper Foil Substrate (Copper Film)
Copper Foil: Basically, there are two types of copper foil: electrolytic copper and calendered copper. Thickness of the common 1oz and 1/2oz.
Substrate film: the common thickness of 1mil and 1/2mil two.
Adhesive: Thickness is determined by customer requirements.
Cover Film (Cover Film)
Cover Film: Surface insulation. Common thicknesses are 1mil and 1/2mil.
Adhesive: Thickness is determined by customer requirements.
Release paper: Avoids adhesive from sticking to foreign objects before pressing; facilitates operation.
PI Stiffener Film (PI Stiffener Film)
PI Stiffener Film: reinforces the mechanical strength of the FPC and facilitates the surface mounting process. Common thicknesses range from 3mil to 9mil.
Adhesive: Thickness is determined by customer requirements.
Release paper: to avoid adhesive in the pressure before the adhesion of foreign objects. PCB flexible circuit is designed to improve space utilization and product design flexibility to meet the needs of smaller and higher density installation of the design, but also help to reduce the assembly process and enhance reliability. It is the only solution to meet the miniaturization and mobility requirements of electronic products. Flexible circuits are copper circuits etched onto a polymer substrate, or printed polymer thick film circuits. Design solutions for thin, lightweight, compact and complex devices range from single-sided conductive circuits to complex multi-layer, three-dimensional packages. The total mass and volume of flexible packages can be reduced by up to 70% over traditional meta-conductor wire harness methods. Flexible circuits can also have their strength increased through the use of reinforcing materials or linerboards for additional mechanical stability. PCB flex circuits can be moved, bent, and twisted without damaging the wires and can come in different shapes and special package sizes. Its only limitation is the volume space issue. Because they can withstand millions of dynamic bends, flex circuits can be well suited for internal connection systems in continuous motion or periodic motion as part of the end product functionality. A number of products requiring electrical signal/power movement with small form factor/package size benefit from flexible circuits. PCB flex circuits offer excellent electrical properties. The low dielectric constant allows for fast electrical signal transfer; good thermal properties allow for easy cooling of the component; and the high glass transition temperature or melting point allows the component to operate well at higher temperatures. Flexible circuits offer higher assembly reliability and yield due to the reduction of hardware required for internal connections, such as solder joints, relays, backplane lines, and cables commonly found on traditional electronic packages. This is because traditional inline hardware consisting of complex multiple systems is susceptible to a high rate of component misalignment during assembly. With the advent of quality engineering, a flexible system with a very thin thickness is designed to be assembled in only one way, thereby eliminating the human error normally associated with stand-alone wiring engineering. Early flexible circuits were mainly used in areas such as small or thin electronics and connections between rigid printed boards. In the late 1970s, it was gradually applied to computers, digital cameras, inkjet printers, car stereos, CD-ROM drives (see Figure 13-1), and hard disk drives, among other electronic products. When you open a 35mm camera, there are 9-14 different flexible circuits inside. The only way to reduce size is to have smaller components, more precise lines, tighter pitches, and bendable objects. Pacemakers, medical devices, video cameras, hearing aids, laptop computers-almost everything in use today has flexible circuits in it. 2 A double-sided flexible board is a conductive pattern made by etching a layer on each side of an insulating base film. Metallized holes connect the graphics on both sides of the insulating material to form conductive pathways to meet the design and use function of the flex. And cover the film can protect single and double-sided wires and indicate the location of the components placed. Second, the function of PCB flexible circuits 1. PCB flexible circuits of flexural and reliability Currently PCB flexible circuits are: single-sided, double-sided, multi-layer flexible boards and just four kinds of flexible boards. Various types of flexible boards are shown in Figure 13-2. 1 single-sided flexible board is the lowest cost, when the electrical performance requirements are not high printed board. In the single-sided wiring, should choose a single-sided flexible board. It has a layer of chemically etched conductive graphics, and the conductive graphics layer on the flexible insulating substrate surface is calendered copper foil. Insulating substrates can be polyimide, polyethylene terephthalate, aramid fiber ester and polyvinyl chloride. 2 Double-sided flexible board is a conductive graphic layer made by etching on each of the two sides of the insulating base film. Metallized holes connect the graphics on both sides of the insulating material to form conductive pathways to meet the design and use functions of the flex. The cover film protects the single and double-sided wires and indicates where the components are to be placed. 3 Multilayer flexible board is " layer or more layers of single-sided or double-sided flexible circuits laminated together, through drilling, plating to form metallization holes in the different layers to form a conductive pathway. This eliminates the need for complex soldering processes. Multi-layer circuits make a huge functional difference in terms of higher reliability, better thermal conductivity and easier assembly performance. The interaction of assembly dimensions, number of layers and flexibility should be taken into account when designing the layout. 4 Conventional rigid-flex panels consist of rigid and flexible substrates selectively laminated together. The structure is tightly packed with metallized holes to form conductive connections. If a printed board has components on both the front and back sides, a rigid-flexible board is a good choice. However, if all the components are on one side, it would be more economical to choose a double-sided flexible board with a layer of FR-4 reinforcement laminated on its back side. The PCB flexible circuit industry is in the midst of small but rapid development. The polymer thick film method is a highly efficient, low-cost production process. The process selectively screen prints conductive polymer inks on inexpensive flexible substrates. A representative flexible substrate is PET. polymer thick film conductors include screen-printed metallic or toner fillers. The polymer thick film method is inherently clean, uses lead-free SMT adhesives, and does not require etching. Because of its additive process and low substrate cost, polymer thick film circuits are 1/10 the price of copper polyimide thin film circuits and 1/2 to 1/3 the price of rigid circuit boards. polymer thick film is particularly well suited for device control panels. In cell phones and other portable products, polymer thick film is suitable for converting components, switches and lighting devices on printed circuit boards into polymer thick film circuits. Both cost and energy savings are realized. 5 Hybrid-structured PCB flex circuits are multilayer boards with conductive layers made of different metals. An 8-layer board uses FR-4 as the dielectric for the inner layer and polyimide as the dielectric for the outer layer, with leads protruding from the main board in three different directions, each made of a different metal. Conoco alloy, copper and gold are used as separate leads. This hybrid structure is mostly used in the relationship between electrical signal conversion and heat conversion and the electrical properties of the more demanding low-temperature situation, is the only feasible solution. It can be evaluated by the convenience and total cost of the internal connection design to achieve the best performance-price ratio. 2. Economics of PCB Flex Circuits If the circuit design is relatively simple, the total volume is not too large, and the space is suitable, most of the traditional methods of internal connection are much cheaper. If the circuit is complex, handles many signals or has special electrical or mechanical performance requirements, flexible circuits are a better design choice. When the size and performance of the application exceeds the capabilities of a rigid circuit, the flexible assembly method is the most economical. Flexible circuits can be made on a single sheet of film with 12 mil pads with 5 mil via holes inside and 3 mil lines and spacing. Therefore, it is more reliable to mount chips directly on the film. This is because it does not contain flame retardants that can be a source of ionic drilling contamination. These films may be protective and cure at higher temperatures to get a higher glass transition temperature. The reason for the cost savings of flexible materials over rigid materials is the elimination of connectors. The high cost of raw materials is the main reason for the high price of flexible circuits. The price of raw materials varies greatly, the cost of raw materials used in the lowest-cost polyester flexible circuits is 1.5 times the cost of raw materials used in rigid circuits; high-performance polyimide flexible circuits are up to four times or more. At the same time, the flexible nature of the material makes it difficult to automate the manufacturing process, resulting in lower yields; in the final assembly process is prone to defects, these defects include peeling off the flexible attachment, line breakage. These are more likely to occur when the design is not suitable for the application. Under high stresses caused by bending or molding, it is often necessary to select reinforcing or strengthening materials. Despite the high cost of its raw materials, manufacturing trouble, but foldable, bendable and multi-layer collocation function, will make the overall component size reduction, the material used to reduce the subsequent reduction in the total assembly cost. Generally speaking, PCB flexible circuits do cost more than rigid circuits. When flexible boards are manufactured, in many cases they have to face the fact that many of the parameters are out of tolerance. The difficulty in manufacturing flexible circuits lies in the flexibility of the material. 3. Cost of PCB Flexible Circuits Despite the cost aspects mentioned above, the price of flexible assemblies is decreasing and becoming close to the traditional rigid circuits. The main reasons for this are the introduction of newer materials, improved production processes and changes in construction. The construction now allows for a more thermally stable product with few material mismatches. Some of the newer materials allow for more precise lines due to thinner layers of copper, making the components lighter and more suitable for fitting into smaller spaces. In the past, copper foils were adhered to an adhesive-coated medium using a roller pressing process; today, copper foils can be produced directly on the medium without the use of adhesives. These techniques result in copper layers several micrometers thick and precision lines of 3 mils or even narrower widths. Flexible circuits are flame retardant when certain adhesives are removed. This both speeds up the UL certification process and further reduces costs. Flexible circuit board solder masks and other surface coatings enable flexible assembly costs to be further reduced. In the coming years, smaller, more complex and more costly flexible circuits will require more innovative methods of assembly and an increase in hybrid flexible circuits. The challenge for the flexible circuit industry is to capitalize on its technological strengths and keep pace with computer, telecommunication, consumer demand, and dynamic markets. In addition, flexible circuits will play an important role in the lead-free initiative.
Combine that with the fact that I don't understand oh!