JP3877877B2 - Wiring board manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a flexible wiring board or a multilayer wiring board used for electronic equipment, etc., and a method for thermocompression-bonding an insulating protective resin film to a wiring circuit board or etching during wiring formation of a multilayer wiring board. The present invention relates to a method of bonding a dry film resist used in a process and a plating process to a substrate.
[0002]
[Prior art]
FIG. 9 shows a layer configuration diagram of the flexible wiring board. The insulating protective film 3 is manufactured by thermocompression bonding on the upper surface of the base substrate 2 to which the wiring circuit 1 has been applied in advance. An insulating adhesive is applied to the surfaces of the base substrate 2 and the insulating protective film 3 to be thermocompression bonded. In addition, the wiring board has a form in which a circuit is formed only on one side of the board, a circuit in which a circuit is formed on both sides of the board, and the both sides are electrically connected by a through hole. The thickness of the wiring circuit 1 on these substrates may be equivalent to the thickness of the insulating protective film 3 from the viewpoint of the allowable value of the current conducted to the circuit and the flexibility.
[0003]
FIG. 10 shows an outline of a thermocompression bonding method for a single-sided flexible wiring board. The insulating protective film 3 with adhesive and the base substrate 2 are inserted between the hot plates 5 with the cushion material 4 attached to the surface, and the adhesive of the insulating protective film 3 with adhesive is melt-flowed, heated The single-sided flexible wiring board 6 is manufactured by curing and thermocompression bonding. In order to fill the gap between the insulating protective film 3 with adhesive and the wiring circuit 1 during the thermocompression bonding, the cushion material 4 needs to be deformed according to the shape of the wiring circuit 1.
[0004]
In the conventional method, since the cushion material 4 is used, there may be a problem that bubbles remain in the insulating material of the flexible wiring board 6 after molding and a problem associated therewith.
[0005]
First of all, in order not to leave the bubbles in the thermocompression bonding, the temperature of the insulating protective film 3 with the adhesive and the base substrate 2 is sufficiently increased, and the fluidity of the adhesive during the thermocompression bonding is increased. Need to increase. As the material of the cushion material 4, heat-resistant rubber, paper, or the like is used. However, since these materials have poor thermal conductivity, the temperature hardly rises. When pressing a flexible printed circuit board continuously, it takes time to raise the heat removed from the press in one board molding to the temperature required for the next thermocompression bonding. The next press may be done. For this reason, since the fluidity of the adhesive deteriorates due to insufficient temperature rise, the amount of adhesive filled in the gap between the wiring circuit 1 and the insulating protective film 3 becomes insufficient. This causes voids.
[0006]
Secondly, deterioration of the compression deformation characteristics of the cushion material 4 can be mentioned. The material of the cushion material 4 is rubber or paper as described above. For this reason, if heating and cooling are repeatedly performed by thermocompression and pressure and pressure are repeated, the compressive deformability of the cushion material 4 deteriorates, and the cushion material 4 deformed by thermocompression molding is the next of the flexible wiring board to be molded. Since it does not return to the original state before thermocompression bonding is started, the deformation of the cushion material 4 does not follow the shape of the wiring circuit 1, and voids are likely to occur. Naturally, this deterioration becomes more prominent as the operating time of the hot press becomes longer, and the deteriorated cushion material 4 needs to be removed from the hot press and replaced with a new one. During this exchange, there may be secondary problems such as the hot press being unusable for production.
[0007]
FIG. 11 shows an example of a conventional method for continuously manufacturing flexible wiring boards using a roll-shaped pressurizing mechanism. In FIG. 9, the pressurizing and heating mechanism 7 is a roll-shaped forming mechanism in which the insulating protective film 3 is bonded to the base substrate 2 by thermocompression bonding. Depending on the thickness of the insulating protective film 3 and the base substrate 2 used for manufacturing, Some have a mechanism that can adjust the pressure and roll interval. The support roll 8 is a roll for supporting the base substrate 3 and the insulating protective film 2 that are continuously supplied. In order to manufacture a continuous flexible wiring board in this manner, the insulating protective film 3 is wound around the roll 9 in advance, and the roll 9 is rotated during molding, thereby continuously protecting the insulating property. This is a mechanism that can supply the film 3 to the roll-shaped pressure heating mechanism 7.
[0008]
The insulating protective film 3 may have a film for protecting the insulating protective film attached in advance to the surface of the insulating protective film 3 that contacts the base substrate. The roll 10 is a mechanism for continuously peeling the protective film before molding. The base substrate 2 is supplied in the same manner as the insulating protective film 3. The base substrate 2 is wound around a roll 11 in advance, and the base substrate 2 is continuously heated in a roll shape by rotating the roll 11 during molding. Supply to mechanism 7.
[0009]
The insulating protective film 3 and the base substrate 2 are thermocompression-bonded by the roll-shaped pressurizing and heating mechanism 7 and the support roll 8 to form a long flexible wiring board 6. Some things need to be made. The ultraviolet lamp 12 irradiates such a material with ultraviolet rays on a continuously formed flexible wiring board. Further, depending on the type of the insulating protective film 3 that is cured by ultraviolet rays, the protective film may be attached in advance to the surface of the insulating protective film 3, that is, the surface that is irradiated with ultraviolet rays. The roll 13 is a roll for peeling off the protective film. Finally, the flexible wiring board 6 is wound up by the roll 14, and the flexible wiring board can be manufactured continuously.
[0010]
In this example of the conventional method, the flexible wiring board can be continuously manufactured, so that the manufacturing cost can be reduced. However, the roll used for the pressurizing and heating mechanism 7 is a rubber roll or a roll in which rubber is wound around the roll surface in order to absorb wiring irregularities on the surface of the flexible wiring board or waviness of the board. Therefore, as in the conventional example described with reference to FIG. 11, the rubber of the rubber roll deteriorates during continuous use and does not follow the irregularities of the substrate, which may cause voids to remain.
[0011]
For example, as shown in FIG. 12, when the wiring shape on the substrate is a closed loop wiring with respect to the rotation direction of the roll of the pressurizing and heating mechanism 7 shown in FIG. The follow-up of is often adversely affected. In addition, if the applied pressure or the gap between the rolls is not appropriate, the substrate may be deformed in a wavy shape, and it takes time to adjust it according to the rigidity and thickness of the protective film used for manufacturing and the base substrate. . Furthermore, in this conventional method, since the protective film used for manufacturing and the pressure heating roll are in direct contact with each other, relative slip is likely to occur, and defects such as scratches and the like remain on the surface of the flexible wiring board after manufacturing.
[0012]
[Problems to be solved by the invention]
An object of the present invention is to suppress bubbles remaining in an insulating material after thermocompression bonding of a flexible wiring board and to contact the cushion material or the roll, which are caused by the deterioration of the properties of the cushion material or the rubber properties of the rubber roll. The present invention provides a method for laminating a resin film that suppresses the generation of scratches caused by the above-mentioned process and easily suppresses the wavy deformation that occurs when molding with a rubber roll.
[0013]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, a mold having a plurality of blowing holes through which heated fluid can pass is placed opposite to each other with a gap, and an insulating protective film and a base substrate are inserted in the gap. Since the film can be deformed into the circuit shape of the wiring board by causing the fluid to pass through the blowing hole and generating a hydrostatic pressure in the fluid, no bubbles are left between the protective film and the base substrate. Since the mold and the protective film are not in direct contact when the substrate is manufactured, the protective film is not damaged. Since the hydrostatic pressure is generated by the fluid, wear and deterioration do not occur.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0015]
FIG. 1 is a view showing an apparatus for continuously forming a long flexible wiring board according to an embodiment of the present invention. FIG. 2 is a perspective view of a pressure heating unit of the apparatus of the present invention and a diagram showing a part of a mold. FIG. 3 is a sectional view of the pressure heating unit of the apparatus according to the embodiment of the present invention.
[0016]
In FIG. 1, a supply roll 15 is a roll that continuously supplies a long insulating protective film, and the insulating protective film 3 is wound in advance. The protective film peeling roll 16 is a roll for continuously peeling the protective film of the insulating protective film 3 with the protective film. The base substrate supply roll 17 is a roll that continuously supplies a long base substrate, and the base substrate is wound in advance. The gap control roll 18 is a roll for providing an appropriate distance for bonding the insulating protective film 3 and the base substrate 2 together.
[0017]
The fluid pressure added mold 19 is a mold having a fluid blowing hole for supplying pressure and heat to the insulating protective film 3. The support mold 20 is embedded with a heater 21 in order to receive a force applied to the insulating protective film and the base substrate on the upper surface and to supply a temperature necessary for bonding the base substrate and the insulating protective film together. This is a supporting mold configured as described above. The fluid pressure application mold 19 is spatially held by a screw mechanism that can adjust the gap between the support mold 20 and the thickness of the base substrate and the insulating protective film. Air was used as the fluid in this example. The structure of the fluid blowing hole will be described later. In order to supply heated air to the fluid pressure added mold 19, the air heater 22 is passed through and connected by piping. Air to the air heater 22 is supplied from an air compressor 23. The thermocompression-bonded flexible wiring board is continuously wound up by a winding roll 24.
[0018]
Next, the operation of the apparatus configured as described above will be described. First, the insulating protective film is inserted by the supply roll 15 and the base substrate is continuously inserted by the base substrate supply roll 17 into the gap between the fluid pressure application mold 19 and the support mold 20. The base substrate is heated in advance by the support mold 20 immediately before the insulating protective film and the base substrate are inserted into the gap. Since the insulating protective film and the base substrate are almost in contact with each other by the gap control roll 18, heat from the support mold 20 is supplied by conduction through the base substrate, and at the same time, the fluid of the fluid pressure application mold 19 The temperature of the fluid rises as it is supplied with the heat of the heated fluid that passes through the blowout hole.
[0019]
With this temperature rise, the insulating resin adhesive of the insulating protective film and the insulating resin adhesive of the base substrate are softened. When the insulating resin adhesive is softened, the fluid pressure is applied to the surface of the insulating protective film by the hydrostatic action of the fluid that has passed through the fluid blowing hole by passing through the fluid blowing hole of the fluid pressure adding mold 19. Then, the base substrate and the insulating protective film are bonded together by thermocompression bonding. In the present embodiment, since the resin adhesive is cured only by the heating, it passes through the supporting mold only for the time necessary for curing the insulating resin, and the integrated flexible wiring board is wound up by the winding roll 24.
[0020]
Next, the structure of the blowout hole of the fluid pressure application mold 19 will be described in detail with reference to FIGS. 2A is a perspective view showing the external appearance of the fluid nozzle mold, and B and C are front views of the nozzle portion of the fluid pressure-added mold 19 viewed from the insulating protective film side. FIG. 3 is a cross-sectional view of the blowing hole portion of the fluid pressure application mold 19.
[0021]
As shown in FIG. 2, the fluid pressure application die 19 is disposed at a right angle with respect to the traveling direction of the insulating protective film and the base substrate and covers a longer area than the width of the insulating protective film and the base substrate. I made it. Further, as shown in FIGS. 2B and 2C, a large number of fluid blowing holes 25 for applying pressure to the insulating protective film are provided on the surface of the fluid pressure applying mold 19 with respect to the insulating protective film. . When the number of the blowout holes is small, there may be a case where a sufficient pressing force cannot be obtained. The shape of the blowout hole 25 may be circular as shown in B, but even if it is slit as shown in C, the same effect is exhibited. In the embodiment of the circular blowout hole shown in B, the diameter of the hole was set to 0.5 mm or less, and the number of holes was set to about 100.
[0022]
Here, increasing the area of the blowing hole increases the pressure, but at the same time the flow rate of the fluid flowing out of the blowing hole increases, and the heating capacity of the air heater 22 shown in FIG. Depending on the air supply capacity, an appropriate pressure may not be obtained.
[0023]
Therefore, in order to obtain a stable applied pressure, as shown in FIG. 3, a fluid reservoir 26 is installed in the rear part of the blowing hole 25 of the fluid pressure adding mold 19, and sufficient pressure is applied to the blowing hole 25. The structure was
[0024]
In the molding apparatus configured as described above, the surface of the insulating protective film is a mold when the insulating protective film and the base substrate are thermocompression bonded by causing the fluid to pass through the blowing holes and generating hydrostatic pressure in the fluid. Insulating protective film is not damaged. Further, since the insulating protective film can be deformed into the uneven shape of the wiring circuit of the base substrate by the hydrostatic pressure of the fluid, no bubbles are left between the insulating protective film and the base substrate. Further, since a roll-shaped pressurizing mechanism is not used, corrugated deformation does not occur in the molded flexible wiring board.
[0025]
Another embodiment will be described with reference to FIG.
[0026]
In the above embodiment, the base substrate passes through the supporting mold, so that the contact portion exists. Since the base substrate has a higher rigidity than the insulating protective film, the surface scratch is less likely to occur. However, depending on the conditions, the surface substrate may be damaged. In order to improve this point, a fluid pressure applying mold 19 is also installed on the side supporting the base substrate, and the base substrate is not in contact with the mold.
[0027]
Another embodiment will be described with reference to FIG.
[0028]
In the embodiment described with reference to FIG. 1, the insulating resin is melt-cured only by heating the fluid pressure application mold and the supporting mold. Since such an insulating resin generally has a long curing time, the molding speed may be slow. The embodiment of FIG. 5 is an embodiment in which a photocuring step by ultraviolet irradiation is added to the curing that is insufficient only by heating. The ultraviolet irradiation lamp 27 in FIG. 5 is an ultraviolet irradiation device that checks ultraviolet rays. The winding roll 28 is a roll for protecting the insulating protective film and continuously removing the protective film after the insulating resin is cured.
[0029]
Another embodiment will be described with reference to FIG.
[0030]
In the embodiment described with reference to FIG. 1, the method uses the pressure of the fluid flowing out from the blowing hole of the fluid pressure addition mold. For this reason, a fluid pressure source for generating pressure in the fluid is necessary. In this embodiment, since the amount of air flowing out from the blowout hole is large, it is necessary to use an air compressor having a considerably large supply capacity. In order to improve this point, a method for obtaining the hydrostatic pressure of the fluid pressure added to the insulating protective film by dynamic pressure is shown in FIG.
[0031]
In FIG. 6, a supply roll 29 is a roll for continuously feeding out the insulating protective film, a take-up roll 30 is a roll for peeling off the protective film of the insulating protective film and winding up, and a supply roll 31 is a base substrate. It is a roll for continuous supply. The dynamic pressure generating drum 32 is a mechanism for generating dynamic pressure by rotating at high speed. The support die 33 is a roll for heating the insulating protective film and the base substrate and receiving dynamic pressure generated by the high-speed rotation of the dynamic pressure generating drum 32, and laminating the insulating protective film and the base substrate for thermocompression bonding. It is.
[0032]
In the present embodiment, first, the insulating protective film and the base substrate are respectively installed on the supply rolls 29 and 31 and the take-up roll 34, and then the support mold 33 is heated to thermally press the insulating protective film and the base substrate. Set the temperature as required. Thereafter, the dynamic pressure generating drum is rotated at a high speed to generate pressure between the support mold 33, the insulating protective film, and the base substrate. In order to generate pressure by rotating the dynamic pressure generating drum 32 at a high speed, a groove 35 generally called a herringbone groove as shown in FIG. 7 is formed on the circumferential surface of the dynamic pressure generating drum 32. . The groove 33 generates a dynamic pressure stably.
[0033]
In the molding apparatus configured as described above, the insulating protective film and the base substrate can be continuously bonded by thermocompression bonding as in the above-described embodiment. Further, since the dynamic pressure generating drum 32 and the insulating protective film are not in contact with each other, no defects such as dents and scratches are generated on the flexible wiring board integrated between the support mold 33 and the dynamic pressure generating drum 32. . Further, in this embodiment, since the fluid pressure for bonding is obtained only by the rotation of the dynamic pressure generating drum 32, there is a feature that an air pressure source such as the compressed air device described in the above embodiment is unnecessary.
[0034]
In this embodiment, the area in contact with the heating mold on the base substrate side is larger than in the embodiment shown in FIG. For this reason, although the speed | rate which sends a board | substrate continuously can also be quickened, on the other hand, the force required for winding after bonding will also become large. In particular, when the thickness of the base substrate is reduced, the rigidity of the substrate is lowered, and thus deformation due to the winding force may occur. In order to prevent such a situation, when an extremely thin substrate is manufactured, it is necessary to use a carrier sheet 36 for carrying the base substrate and the insulating protective film as shown in FIG. FIG. 8 shows that the carrier sheet feeding roll 37 and the winding roll 38 are added to the embodiment described in FIG. 6 so that the feeding speed of the insulating protective film, the base substrate, and the feeding speed of the carrier sheet 36 are the same. Thus, no tensile force is applied to the insulating protective film and the base substrate, and the flexible wiring substrate after the molding is not deformed.
[0035]
【The invention's effect】
According to the present invention, air bubbles in the flexible wiring board can be eliminated, and scratches due to contact with the mold do not occur, so that a highly reliable flexible wiring board can be manufactured.
[Brief description of the drawings]
FIG. 1 is a view for explaining an apparatus for continuously forming a long flexible wiring board according to an embodiment of the present invention.
FIG. 2A is a perspective view of a pressure heating unit of the apparatus of the present invention, and B and C are plan views showing one surface of the pressure heating unit of the apparatus of the present invention.
FIG. 3 is a cross-sectional view for explaining a pressure heating unit of an apparatus according to an embodiment of the present invention.
FIG. 4 is a view for explaining an apparatus for forming a flexible wiring board without completely contacting the flexible wiring board with the pressurizing and heating unit facing each other according to an embodiment of the present invention. It is.
FIG. 5 is a view for explaining an apparatus for molding by irradiating ultraviolet rays onto a flexible wiring board molded by a pressure heating unit according to an embodiment of the present invention to promote curing of a resin.
FIG. 6 is a view for explaining an apparatus for manufacturing a long flexible wiring board by generating an additional pressure by rotating a drum at a high speed according to an embodiment of the present invention.
FIG. 7 is a view for explaining the shape of the circumferential surface of a drum that rotates at a high speed and generates an additional pressure according to an embodiment of the present invention.
FIG. 8 is a diagram for explaining an apparatus for generating an additional pressure by rotating a drum at a high speed according to an embodiment of the present invention.
FIG. 9 is a diagram for explaining a method for manufacturing a long flexible wiring board using a conventional roll-shaped pressurizing mechanism.
FIG. 10 is a cross-sectional view showing a configuration of a flexible wiring board according to the present invention.
FIG. 11 is a diagram for explaining a conventional method of manufacturing a flexible wiring board.
FIG. 12 is a view for explaining a void (bubble) remaining defect of a conventional flexible wiring board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Wiring circuit, 2 ... Base board, 3 ... Insulating protective film, 4 ... Cushion material, 5 ... Hot plate, 6 ... Flexible wiring board, 7 ... Roll-shaped pressurization heating mechanism, 8 ... Support roll, 9, DESCRIPTION OF SYMBOLS 10,11 ... Roll, 12 ... Ultraviolet lamp, 13, 14 ... Roll, 15 ... Supply roll, 16 ... Protective film peeling roll, 17 ... Base substrate supply roll, 18 ... Gap control roll, 19 ... Fluid pressure addition metal mold | die , 20 ... supporting mold, 21 ... heater, 22 ... air heater, 23 ... air compressor, 24 ... winding roll, 25 ... blowout hole, 26 ... fluid reservoir, 27 ... UV irradiation lamp, 28 ... winding Take-up roll, 29 ... Supply roll, 30 ... Take-up roll, 30 ... Take-up roll, 31 ... Supply roll, 32 ... Drum for dynamic pressure generation, 33 ... Support mold, 34 ... Take-up roll 35 ... groove, 36 ... carrier sheet, 37 ... carrier sheet feed roll, 38 ... the take-up roll.

Claims (3)

Apply the adhesive on at least one of the surfaces to which the wiring substrate on which the wiring is formed and the resin film are bonded to each other, and put them into the bonding process,
A fluid heated to a softening temperature of the adhesive from a mold having a plurality of fluid blowing holes from one side or both sides of the stacked wiring board or resin film, and the mold Fill the gap between the wiring board or the resin film, heat the adhesive sandwiched between the wiring board and the resin film, and pressurize the wiring board and the resin film with hydrostatic pressure,
A method for manufacturing a wiring board, comprising: bonding the wiring board and the resin film by curing the adhesive by heating with the fluid. Apply the adhesive on at least one of the surfaces to be bonded to each other, and let the wiring board on which the wiring is formed and the resin film pass through the gap between the heatable mold and the drum facing each other. ,
Softening the adhesive by heat from the heated mold,
The drum having grooves formed on the circumferential surface is rotated at a high speed to generate pressure in the gap between the mold and the drum due to the viscosity of air, and pressurize the wiring board and the resin film in a bonding direction. And closely
A method of manufacturing a wiring board, comprising: bonding the resin film and the wiring board by curing the adhesive by heating from the mold.   3. The method for manufacturing a wiring board according to claim 2, wherein a herringbone groove is formed on a circumferential surface of the drum.

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