1. Characteristics of flexible PCB circuit
Flexible PCB circuit Small size Light weight Flexible PCB circuit boards were originally designed to replace larger harness wires. In today's cutting-edge electronic device assembly boards, flexible PCB circuits are often the only solution to meet miniaturization and mobility requirements. Flexible PCB circuits (sometimes called flexible printed circuits) are copper PCB circuits etched on a polymer substrate or printed polymer thick film PCB circuits. For devices that are both thin and light, their design solutions range from single-sided conductive circuits to complex multi-layer three-dimensional assemblies. The total weight and volume of the flexible assembly is reduced by 70% compared to the traditional circular wire harness method. Flexible PCB circuits can also increase their strength by using reinforcing materials or liner methods to obtain additional mechanical stability.
Flexible PCB circuit Mobile bending torsion Flexible PCB circuit can move, bend and twist without damaging the wire, can comply with different shapes and special package sizes. Its only limitation is the problem of volume space. Because it can withstand millions of dynamic bends, flexible PCB circuits are well suited for continuous or periodic motion in connected systems, becoming part of the final product function. The solder joint on a rigid PCB is subjected to thermal mechanical stress and will fail after hundreds of cycles. Randy Lia, product manager at Shel-dahl, Northfield, Minn, said, "Certain products that require electrical/power movement and have a smaller form factor/package size benefit
Flexible PCB circuit."
Flexible PCB circuit has excellent electrical properties Dielectric properties Heat resistance Flexible PCB circuit provides excellent electrical properties. Don friedman, chief executive of Inter-national Flex TEchnologies, Endicott, in New York. "The low dielectric constant allows for fast transmission of electrical signals; Good thermal performance makes components easy to cool down; The higher glass transition temperature or melting point allows the components to function well at higher temperatures."
Flexible PCB circuits have higher assembly reliability and yield Flexible PCB circuits reduce the hardware required for internal connection, such as solder joints, trunks, baseplate lines and cables commonly used in traditional electronic packages, so that flexible PCB circuits can provide higher assembly reliability and yield. Because the traditional embedded hardware composed of complex multiple systems is prone to high component dislocation rate during assembly. "Flexible PCB circuits have low stiffness and small size, and because flexible PCB board components are smaller in size, less material is used," said Mike Giesler, marketing manager for 3M Electronic Products Division, Austinm, Texas. With the advent of quality engineering, a thin flexible system was designed to be assembled in only one way, thus eliminating many of the human errors normally associated with independent wiring engineering.
The use of flexible components is increasing dramatically. Jim Barry, president and general manager of Strataflex Hudson, N.H., said: "When you pick up almost any appliance today, you will find a flexible group in it. quot; . Open up a 35mm camera, and there are 9 to 14 different flexible PCB circuits in it, because cameras are getting smaller and more capable. The only way to reduce volume is to have smaller components, finer lines, tighter pitch, and flexible objects. Pacemakers, medical devices, video cameras, hearing AIDS, portable computers - almost everything we use today has flexible PCB circuits in it."
2. Advantages and efficacy of flexible PCB circuit
2.1 Flexure and reliability of flexible PCB circuit
At present, there are four types of flexible PCB circuits: single-sided, double-sided, multi-layer and rigid-torsion combined. "Single-sided flexible plates have the lowest cost," Friedman said. When the electrical performance requirements are not high, and single-sided wiring can be used, single-sided flexible plates should be used." This most common form has found commercial applications, such as ink cartridges for printers and memory for computers. The single-sided flexible plate has a layer of chemically etched conductive pattern, and the conductive pattern layer on the surface of the flexible insulating substrate is calendered copper foil. Insulating substrates used for flexible assembly can be polyimide (Kapton), polyethylene terephthalate (PET), arylamide fibre paper (Nomex) and polyvinyl chloride (PVC).
The double-sided flexible plate is a conductive pattern made of a layer etched on each of the two faces of the base film. Metallized holes connect the patterns on both sides of the insulating material to form a conductive path to meet the flexible design and use function. The covering film can protect the single and double-sided wires and indicate the position of the components.
Multi-layer flexible board is to layer three or more layers of single-sided flexible PCB circuit or double-sided flexible PCB circuit together, through drilling, electroplating to form a metallized hole, forming a conductive path between different layers. This eliminates the need for complex welding processes. Al Balzano, vice president and general manager of Basic Electronics in Garden Grove, California, said, "Multilayer PCB circuits make a huge difference in terms of higher reliability, better thermal conductivity and easier assembly performance." Although the number of conductive layers designed to be flexible can be unlimited, the interaction between assembly size, number of layers and flexibility should be taken into account when designing the layout in order to ensure easy assembly.