FPC flexible circuit board flexura and reliability
1.The FPC has four kinds: single side, double side, multi-layer flexible plate and just flexible plate.
1.The FPC has four kinds: single side, double side, multi-layer flexible plate and just flexible plate.
①Single flexible plate is the lowest cost, when the PCB for electrical demand is not high。Single flexible circuit board has a chemical etching out the layer of conductive graphics，In flexible conductive graphics layer on the surface of the insulating substrate for rolled copper foil.Insulating base material can be polyimide, polyethylene terephthalate, aromatic polyamide fiber resin and PVC.
②Double flexible plate is on the two sides each have a layer of insulating base film etching made of conductive graphics.Metallized hole to both sides of the insulation materials connection form a conductive path, in order to meet the deflection design and use of the function.While covering film can protect the single and double wires and components placed.
③Multi-layer flexible plate is a level 3 or more layers of single sided or double sided laminated flexible circuit together.，Through the drill away L form metal, electroplating, the formation of a conductive path between different layers.Multi-layer circuit in higher reliability, better thermal conductivity and convenient assembly has huge function differences in performance.When designing the layout, assembly shall be taken into consideration, layer number and size of flexible influence each other.
④Traditional just flexible plate is made from rigid and flexible substrate has a choice of formation pressure together.Structure closely to metallization away L form electrical connection..If a PCB is, opposite element, just flexible plate is a good choice.But if all the components are on one side, selects the double flexible plate, and on the back of the laminated layer on FR4 reinforced material, will be more economic.
⑤Hybrid structure is a kind of sandwich plate, flexible circuit conductive layer made of different metals.A eight layer plate using FR - 4 as inner medium, use polyimide as the outer layer of the medium,Out from three different direction of the motherboard, lead each wire made of different metals.Constantan alloy, copper and gold as independent lead, respectively.This kind of hybrid structure is mostly used in electrical signal conversion and is quite harsh relationship and performance of heat transformation of low temperature circumstances, is the only feasible solution.
2．FPC flexible circuit board of the 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.
The high cost of raw materials is flexible circuits of the main causes of high price.Cost of raw material price difference is bigger, the lowest polyester raw materials used in flexible circuit cost is 1.5 times that of the raw materials used in rigid circuit;High-performance polyimide flexible circuits, up to 4 times or more.At the same time, the flexible material could make it not easy to automate process in the manufacturing process, leading to the decline in output;Liable to occur in the final assembly process defects, these defects including off flexible attachment, line breaks.When the design is not suitable for application, such cases are more likely to happen.Under the high stress caused by bending or molding, often need to choose the reinforced material or reinforcing materials.Despite the high cost of raw materials, manufacture of trouble, but folding, flexible and multi-layer makeup function, will reduce the overall component size, use less material, reduce the total assembly cost.
3．The cost of FPC flexible circuit board
Despite the cost of the above factors, the flexible assembly price is falling, become and close to the traditional rigid circuit.The main reason is the introduction of updated materials, improved the production process and the change of the structure.Now so that the thermal stability of the product is higher, there are few materials do not match.Some of the updated material for copper layer is thinner and can make more precise line, make the component more light, more suited to put into a small space.In the past, the rolling process of copper foil adhesion in coated with adhesives on the medium, now, can not directly use adhesives in medium generated on the copper foil.These techniques can get several microns thick copper layer, get a 3 m. 1 even more narrow width precision line.After removed some adhesives flexible circuit has the flame retardant performance.It can accelerate the uL certification process and can further reduce the cost.The surface of the flexible circuit board solder mask and other coating made of flexible assembly further reduce the cost.
In the next few years, smaller, more complex and assembly cost higher FPC flexible circuit boards will require more novel methods of assembly, and mixed flexible circuits may be increased.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.
②Double flexible plate is on the two sides each have a layer of insulating base film etching made of conductive graphics.Metallized hole to both sides of the insulation materials connection form a conductive path, in order to meet the deflection design and use of the function.While covering film can protect the single and double wires and components placed.
③Multi-layer flexible plate is a level 3 or more layers of single sided or double sided laminated flexible circuit together.，Through the drill away L form metal, electroplating, the formation of a conductive path between different layers.Multi-layer circuit in higher reliability, better thermal conductivity and convenient assembly has huge function differences in performance.When designing the layout, assembly shall be taken into consideration, layer number and size of flexible influence each other.
④Traditional just flexible plate is made from rigid and flexible substrate has a choice of formation pressure together.Structure closely to metallization away L form electrical connection..If a PCB is, opposite element, just flexible plate is a good choice.But if all the components are on one side, selects the double flexible plate, and on the back of the laminated layer on FR4 reinforced material, will be more economic.
⑤Hybrid structure is a kind of sandwich plate, flexible circuit conductive layer made of different metals.A eight layer plate using FR - 4 as inner medium, use polyimide as the outer layer of the medium,Out from three different direction of the motherboard, lead each wire made of different metals.Constantan alloy, copper and gold as independent lead, respectively.This kind of hybrid structure is mostly used in electrical signal conversion and is quite harsh relationship and performance of heat transformation of low temperature circumstances, is the only feasible solution.
2．FPC flexible circuit board of the 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.
The high cost of raw materials is flexible circuits of the main causes of high price.Cost of raw material price difference is bigger, the lowest polyester raw materials used in flexible circuit cost is 1.5 times that of the raw materials used in rigid circuit;High-performance polyimide flexible circuits, up to 4 times or more.At the same time, the flexible material could make it not easy to automate process in the manufacturing process, leading to the decline in output;Liable to occur in the final assembly process defects, these defects including off flexible attachment, line breaks.When the design is not suitable for application, such cases are more likely to happen.Under the high stress caused by bending or molding, often need to choose the reinforced material or reinforcing materials.Despite the high cost of raw materials, manufacture of trouble, but folding, flexible and multi-layer makeup function, will reduce the overall component size, use less material, reduce the total assembly cost.
3．The cost of FPC flexible circuit board
Despite the cost of the above factors, the flexible assembly price is falling, become and close to the traditional rigid circuit.The main reason is the introduction of updated materials, improved the production process and the change of the structure.Now so that the thermal stability of the product is higher, there are few materials do not match.Some of the updated material for copper layer is thinner and can make more precise line, make the component more light, more suited to put into a small space.In the past, the rolling process of copper foil adhesion in coated with adhesives on the medium, now, can not directly use adhesives in medium generated on the copper foil.These techniques can get several microns thick copper layer, get a 3 m. 1 even more narrow width precision line.After removed some adhesives flexible circuit has the flame retardant performance.It can accelerate the uL certification process and can further reduce the cost.The surface of the flexible circuit board solder mask and other coating made of flexible assembly further reduce the cost.
In the next few years, smaller, more complex and assembly cost higher FPC flexible circuit boards will require more novel methods of assembly, and mixed flexible circuits may be increased.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.
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