Jiangmen double-sided FPC manufacturing process full solution process

FPC board - double - sided flexible circuit board manufacturing process  

FPC board in addition to some materials, FPC board materials are basically rolled.  Because not all processes must be processed with roll tape process, some processes must be cut into sheet to process, such as double-sided FPC board metallized hole drilling, currently can only be drilled in sheet form, so double-sided FPC board the first process is to open.  

Flexible copper-clad laminates are easy to be injured due to their poor bearing capacity to external forces.  If the material is damaged during opening, it will have a serious impact on the pass rate of subsequent processes.  Therefore, even if it appears to be very simple material, in order to ensure the quality of the material, it must be given enough attention.  If the amount is relatively small, you can use manual shears or hob cutters, large quantities, available automatic shears.  

Whether it is single side, double side copper foil laminate or covering film, the precision of cutting size can reach ± o.33.  High reliability of opening material, open good materials automatically neatly stacked, in the exit does not need personnel to collect material.  Can control the damage to the material in the minimum, using the change of the size of the feeding roller, the material almost no wrinkle, scar.  And the latest device can also roll tape etching FPC board for automatic cutting, the use of optical sensors can detect the corrosion positioning graphics, automatic opening positioning, opening precision up to O. 3mm, but can not be this opening frame as the next process positioning.  

FPC board drilling through hole - double - sided flexible circuit board manufacturing process  

The through hole of FPC board can be drilled by NUMERICAL control as well as rigid printed board, but it is not suitable for hole machining of coil with double-sided metallized hole circuit.  With the high density of the circuit graphics and the small aperture of the metallized hole, plus the aperture of nc drilling has a certain limit, now many new drilling technology has paid the practical application.  These new drilling techniques include plasma etching hole, laser drilling, punching hole, chemical etching hole, etc. These drilling techniques are easier to meet the requirements of the winding process than CNC drilling.  

The through hole of FPC board can be drilled by NUMERICAL control as well as rigid printed board, but it is not suitable for hole machining of coil with double-sided metallized hole circuit.  With the high density of the circuit graphics and the small aperture of the metallized hole, plus the aperture of nc drilling has a certain limit, now many new drilling technology has paid the practical application.  These new drilling techniques include plasma etching hole, laser drilling, micro-aperture punching, chemical etching hole, etc. These drilling techniques are easier to meet the hole formation requirements of the winding process than CNC drilling.  

1.  Nc drilling  

Double-sided FPC board through the drilling hole is now mostly still with CNC drilling machine, CNC drilling machine and FPC board using CNC drilling machine is basically the same, but the drilling conditions are different.  Because the FPC board is very thin, it is able to overlap multiple pieces of drilling, if the drilling conditions are good, 10 to 15 pieces can be overlapped together for drilling.  The backing plate and cover plate can use paper based phenolic laminate or glass fiber cloth epoxy laminate, and also can use 0.2 ~ 0.4mm thick aluminum plate.  Drill bits for FPC boards are available on the market. Drill bits for drilling rigid printed boards and cutter for contour milling can also be used for FPC boards.  

Drilling, milling cover film, and reinforcement plate profiles are basically the same, but due to the softness of the adhesive used by the flexible PRINTED board material, it is very easy to adhere to the bit, requiring frequent testing of the bit condition and increasing the bit speed.  Special care should be taken in drilling holes for multilayer or double-layer FPC boards.  

2.  punching  

Microaperture punching is not a new technology and has been used for mass production.  Because the winding process is continuous production, there are many examples of using punching to process the winding through hole.  But batch punching technology is limited to blunt o. diameter 6 ~ 0.8 mm hole, compared with nc drilling machine drilling processing cycle is long and need manual operation, due to the large size of original process, the punching mould accordingly, so the mold price is very expensive, although mass production to reduce the cost advantage, but the burden of equipment depreciation,  Small volume production and flexibility cannot compete with CNC drilling, so it is still not popular.  

However, in recent years, the die precision of punching technology and numerical control drilling have made great progress, punching in the PRACTICAL application of FPC board has been very feasible.  The latest mold manufacturing technology can produce a hole with a diameter of 75um that can punch and cut the base material 25um thick non-adhesive adhesion-type copper clad foil laminate. The reliability of punching is also quite high. If the punching conditions are suitable, it can even punch holes with a diameter of 50um.  Punching device has also been CNC, mold can be miniaturized, so it can be well applied to the flexible circuit board punching, CNC drilling and punching can not be used for blind hole processing.  

3.  Laser drilling  

With laser can drill the most fine hole, for FPC board drilling hole laser drilling machine has excited excimer laser drill, impact carbon dioxide laser drill, YAG(yttrium aluminum garnet) laser drill, argon laser drill, etc..  

Impact type carbon dioxide laser drill only can carry on the drilling to the base material of insulation layer, and YAG laser drill insulating layer of the base material and copper foil for drilling, drilling and the speed of the insulating layer significantly faster than the speed of drilling and copper foil, in just the same kind of laser drilling machine for all drilling could not have a high production efficiency.  Copper foil is etched first to form a pattern of holes, then the insulation is removed to create a through-hole, so that lasers can drill holes of extremely small sizes.  However, due to the position accuracy of upper and lower holes, the hole diameter may be restricted.  If the blind hole is drilled, as long as the copper foil etching off one side, there is no up and down position accuracy problem.  The process is similar to the plasma and chemical etching holes described below.  

At present, the holes processed by excimer laser are the smallest.  Excited excimer laser is ultraviolet light, directly destroy the structure of the base layer resin, so that the resin molecules dispersed, the heat generated is very small, so you can limit the damage degree of heat around the hole to the minimum range, the hole wall is smooth and vertical.  If the laser beam could be shrunk further, it would be possible to process holes between 10 and 20 µ m in diameter.  Of course, the larger the plate thickness aperture ratio, the more difficult the wet copper plating.  The problem with stimulated excimer laser drilling is that the breakdown of polymers results in carbon black sticking to the hole wall, so some means must be taken to clean the surface to remove the carbon black prior to plating.  However, when laser processing blind holes, there are also some problems in laser uniformity, which will produce bamboo-like residues.  

The biggest difficulty of excimer laser is slow drilling speed and high processing cost.  Therefore, it is limited to the processing of small holes with high precision and high reliability.  

Impact type carbon dioxide laser is generally used carbon dioxide gas as laser source, radiation is infrared, and excited excimer laser combustion decomposition resin molecules due to thermal effect is different, it belongs to thermal decomposition, processing hole shape is much worse than the excited excimer laser, can be processed aperture is basically 70 ~ 100um,  But the processing speed is significantly faster than the excited excimer laser speed, and the cost of drilling is much lower.  Even so, the processing cost is much higher than plasma etching hole method and chemical etching hole method described below, especially if there are many holes per unit area.  

It should be noted that when processing blind holes, the laser can only be fired to the surface of the copper foil, and the organic matter on the surface need not be removed at all. In order to stably clean the copper surface, chemical etching or plasma etching should be used as post-processing.  Considering from the possibility of technology, laser drilling process is basically no difficulty in winding process, but considering the balance of the process and the proportion of equipment investment, it is not dominant, but the width of the Tape chip Automated welding process (TAB, Tape Automated Bonding) is narrow,  Practical examples have been made of the use of a winding process to increase the rate of drilling.  

FPC board manufacturing process product drawing  

Hole metallization - double - sided FPC board manufacturing process  

The hole metallization of FPC board is basically the same as that of rigid printed board.  

In recent years, instead of electroless plating, direct electroplating has been used to form carbon conductive layer.  Hole metallization of FPC boards also introduces this technique.  

FPC board because of its softness, need to have a special fixed fixture, fixture can not only fix the flexible printed board, but also must be stable in the plating solution, otherwise the copper plating thickness is not uniform, which is also an important cause of wire breaking and bridging in the etching process.  To achieve uniform copper plating, the flexible PCB must be taut in the fixture, and the position and shape of the electrodes must be worked out.  

Hole metalization outsourcing processing, as far as possible to avoid outsourcing to the flexible printed board perforation experience of the factory, if there is no FPC board special plating line, the quality of the hole is not guaranteed.  

Copper foil surface cleaning - FPC board manufacturing process  

In order to improve the adhesion of the resist mask, the surface of the copper foil should be cleaned before coating the resist mask. Even such a simple procedure needs special attention for FPC boards.  

FPC board general cleaning chemical cleaning process and mechanical grinding process, for the manufacture of precision graphics, most occasions are to combine the two clean flow process surface treatment.  Mechanical grinding using brush method, brush material too hard will cause damage to the copper foil, too soft and insufficient grinding.  Nylon brush is generally used, and the length and hardness of the brush must be carefully studied.  Use two brush rollers, placed on the conveyor belt, the direction of rotation is opposite to the direction of belt transmission, but at this time if the brush roller pressure is too large, the substrate will be stretched by a great tension, which is one of the important reasons for the size change.  

FPC board if the copper foil surface treatment is not clean, then the adhesion to the resist mask is poor, so it will reduce the qualified rate of etching process.  Due to the recent improvement in the quality of copper foil, the surface cleaning process can also be omitted in the case of single circuit.  However, surface cleaning is an essential process for precision graphics below 1OOμm.  

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