JPH06282062A - Production of three-dimensional circuit board - Google Patents

Abstract

PURPOSE:To form circuits with high-density wirings on the three-dimensional circuit board having large ruggedness differences. CONSTITUTION:The three-dimensional circuit board is produced by including a stage for applying a photoresist 3 on the front surface of the three-dimensional circuit board 1 molded of a resin, superposing a photomask 4 thereon and exposing the photoresist with collimated beams of light, then developing the photoresist. The exposing is executed by using the photomask 4 formed with light transmission parts 4a subjected to the size adjustment meeting the spread of the collimated beams of light according to the spacing between the photomask 4 and the circuit forming surface of the circuit board 1 at this time. The process is so constituted that the exposure can be made by correcting the spread of the collimated beams of light by the spacing between the circuit board 1 and the photomask 4, by which the nonuniformity in the width size of the circuit 6 occurring in the ruggedness on the surface of the circuit board 1 is averted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a three-dimensional circuit board in which circuits are three-dimensionally provided on a three-dimensional surface.

[0002]

2. Description of the Related Art As a printed wiring board, there is provided a three-dimensional circuit board in which a circuit board is made of a resin molded product. This conventional three-dimensional circuit board cannot adopt the conventional circuit forming method, which is based on the assumption that the surface is a flat surface, as it is. Therefore, JP-A-1-298792 and JP-A-4-7 are used.
Various ideas have been made as seen in Japanese Patent No. 6985, Japanese Unexamined Patent Publication No. 1-206692, and US Pat. No. 3,694,080.

FIGS. 3 and 4 show each step of manufacturing the three-dimensional circuit board, and an outline of an example of manufacturing the three-dimensional circuit board will be described with reference to FIGS. 3 and 4. First, a circuit board 1 having a three-dimensional surface as shown in FIG. 3A is formed by resin molding, and after roughening the surface, electroless plating is performed to form a circuit as shown in FIG. 3B. The electroless plating layer 2 is applied to the entire surface of the substrate 1, and then from the top of FIG.
As shown in FIG. 3C, the photoresist 3 is applied over the entire surface, and as shown in FIG. 3D, the photoresist 3 is covered with the photomask 4, exposed, and developed to remove the photoresist 3 in the circuit forming portion. Then, the electroless plating layer 2 is energized to perform electroplating, thereby depositing the electroplating layer 5 on the exposed surface of the electroless plating layer 2 which is not covered with the photoresist 3 as shown in FIG. 4A. , And this electroplating layer 5
4 (b) is plated with nickel or gold to form these plating layers 7, and then the photoresist 3 is peeled off as shown in FIG. 4 (c) and the electroless plating layer 2 is not necessary. By etching the portion, the circuit 6 including the electroless plating layer 2, the electroplating layer 5, and the nickel and gold plating layer 7 can be formed.
Then, by bonding the wire 19 as shown in FIG. 4D, the component 18 such as an electronic component can be mounted on the circuit board 1.

When the circuit is formed as described above, since the surface of the circuit board 1 is three-dimensionally formed, the planar photomask 4 cannot be brought into close contact with the surface of the circuit board 1. Circuit board 1 as in 3 (d)
A gap is created between the concave portion 9 and the photomask 4, and light leakage occurs, which makes it difficult to perform accurate exposure.

For this reason, in Japanese Patent Laid-Open No. 1-298792, a three-dimensional mask is prepared by applying a non-light-transmitting wiring pattern to a light-transmitting mold having a shape of male and female relationship with the solid on the surface of the circuit board. , It is proposed that a three-dimensional mask be brought into close contact with the surface of the circuit board for exposure. However, in order to form a mask in a three-dimensional shape that matches the three-dimensional shape of the surface of the circuit board, a great number of man-hours are required, which poses a serious problem in practical use in terms of production efficiency and production cost.

The problem disclosed in US Pat. No. 3,694,080 has the same problem. That is, this one discloses a method of photoprinting a conductor pattern on the curved surface of the rotor of the converter. As shown in FIG. 30, a rotor 31 having an external curved surface 30 coated with photoresist is attached to an indexing table 32. , The light from the single point light source 33 passes through the lens 34 to form parallel rays,
Rotor 3 through the sub-mask 35 and the main mask 36 which are arranged close to (not in contact with) the outer curved surface 30 of FIG.
The photoresist on the outer curved surface 30 of No. 1 is exposed. In FIG. 30, 37 is a shutter connected to a solenoid 39 operated by a timer 38.
And in this thing, the masks 35 and 36 are the rotor 3
The external curved surface 30 is formed to have the same shape as the curved surface of the external curved surface 30 of FIG. 1, and basically, since the masks 35 and 36 and the external curved surface 30 of the rotor 31 are parallel to each other on all surfaces, Accurate exposure to 30 is possible. However, even in this case, if the surface to be exposed is a three-dimensional surface with complicated irregularities, no consideration is given to changes in the distance between the photomask and the circuit formation surface, so parallel light is not considered. Even if the light is exposed to light, a light diffraction phenomenon is likely to occur, and a problem arises in that an appropriate exposure process cannot be performed.

[0007]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
According to Japanese Patent Laid-Open No. 76985, when the planar photomask 4 is used to perform the exposure as shown in FIG. 3D, the photomask 4 is irradiated with parallel light so that the pattern formed on the photomask 4 is exposed. To be able to do.

By using parallel light in this way, the circuit board 1
When the surface unevenness difference is small, the exposure can be performed with a relatively accurate pattern.
When the recess 9 is deeply formed as shown in FIG. 2 and the distance between the photomask 4 and the circuit forming surface of the circuit board 1 becomes large, even if the light is parallel light, the light may be diffracted by a light diffraction phenomenon or a slight deviation of the light. Spread and the light also circulates from the light transmitting portion 4a to the back side of the light non-transmitting portion 4b, and the photoresist 3 is exposed even on a part of the back side of the light non-transmitting portion 4b.
As a result, of the photoresist 3 on the surface of the circuit board 1, the unexposed portions of the bottoms and slopes of the recesses 9 are thinned, and the width of dissolution during development is narrowed, as shown in FIG. In the circuit 6, the width of the recess 9 is narrow. There is also a problem that the exposure amount becomes uneven on the flat surface and the inclined surface of the circuit board 1.

Although the case where the negative type photoresist 3 is used has been described with reference to FIG. 31, it becomes as shown in FIG. 32 when the positive type photoresist 3 is used. That is, in this case, the light transmitting portion 4a of the photomask 4 is shown in FIG.
It is formed in the same pattern as the circuit 6 formed on the circuit board 1 as shown in (b), but when exposure is performed using parallel light, as shown in FIGS. 32 (a) and 32 (b), the photomask 4 and the circuit board are formed. Concave portion 9a having a large distance from the surface of
At the location 9b, the light spreads due to the light diffraction phenomenon and the like as described above, and the light also circulates from the light transmitting portion 4a to the back side of the light non-transmitting portion 4b, so that the width is wider than the width dimension of the light transmitting portion 4a. The resist 3 will be exposed, and the circuit board 1 will be exposed.
In the photoresist 3 on the surface of the photoresist 3, the bottom of the recesses 9a, 9b and the sloped portion have a wider exposure width and a wider width to be dissolved during development. As shown in FIG. The width of the recesses 9a and 9b was increased.

As a result of the inability to uniformly form the width dimension of the circuit 6 formed on the surface of the circuit board 1 as described above, there arises a problem that high-density wiring cannot be performed. The present invention has been made in view of the above points, and a method for manufacturing a three-dimensional circuit board capable of accurately forming a circuit with high-density wiring even if the unevenness of the surface of the circuit board is complicated and the unevenness is large. It is intended to provide.

[0011]

A method for manufacturing a three-dimensional circuit board according to the present invention comprises applying a photoresist 3 on the surface of a resin-molded three-dimensional circuit board 1 and applying a flat photomask thereon. In manufacturing a three-dimensional circuit board including a step of stacking four layers, exposing them with parallel light, and then developing, a dimension corresponding to the spread of the parallel light with the space between the photomask 4 and the circuit formation surface of the circuit board 1. Exposure is performed using the photomask 4 having the adjusted light transmitting portion 4a formed therein.

In the method for manufacturing a three-dimensional circuit board according to the present invention, a photoresist 3 is applied on the surface of a resin-molded three-dimensional circuit board 1, and a flat photomask 4 is applied thereon.
When manufacturing a three-dimensional circuit board including a step of overlapping and exposing with parallel light and then developing, the photomask 4 is divided into a plurality of stages according to the distance between the photomask 4 and the circuit formation surface of the circuit board 1. It is characterized in that exposure is carried out by superposing.

Further, in performing the exposure with the photomasks 4 in a plurality of stages as described above, the size of the photomask 4 is determined according to the spread of the parallel light accompanying the space between the photomask 4 and the circuit formation surface of the circuit board 1. The photomask 4 having the adjusted light transmitting portion 4a can be used.
As the three-dimensional resin-molded circuit board 1 described above, one in which a concave portion or a convex portion is integrally molded at the time of resin molding and an alignment portion 10 is provided is used. The mask 4 may be superposed on the circuit board 1.

The circuit board 1 is mounted on the circuit board fixing jig 11.
Is set and positioned, and the support bar 12 detachably provided on the photomask 4 is coupled to the circuit board fixing jig 11 so that the photomask 4 is aligned with the circuit board 1. It can be stacked on 1. Further, among the above-mentioned photomasks 4 in a plurality of stages, an exposure mask 4'where a light transmitting portion 4a is patterned on the photomask 4 in one stage is used, and light is not transmitted to the photomasks 4 in other stages. It is also possible to perform exposure using the mask 4 ″, and replace the sequential exposure mask 4 ′ with the light-shielding mask 4 ″ to perform exposure multiple times.

Further, among the photomasks 4 in a plurality of stages, the photomasks 4 may be arranged so that the end portions of adjacent photomasks 4 overlap each other in the irradiation direction of the parallel light. Further, in this way, the end portions of the adjacent photomasks 4 are overlapped with each other in the irradiation direction of the parallel light so that the photomasks 4 are formed.
When arranging, the photomasks 4 may be aligned with each other in the overlapping portion.

When performing the exposure using the parallel light as described above, it is possible to perform the exposure with the parallel light whose parallelism is increased by the collimator 51. Further, a plurality of flat plate-shaped photomasks 4 on which the same exposure pattern is formed are used, and a plurality of photomasks 4 are arranged in the parallel light irradiation direction at predetermined intervals so that the respective exposure patterns are aligned in the parallel light irradiation direction. It is possible to carry out exposure in layers.

Further, the exposure may be performed using the photomask 4 formed by providing the same exposure pattern on the front surface and the back surface, respectively. Further, when performing exposure using parallel light, the laser light 56 can be converted into parallel light by expanding the light flux using the optical lens 52, and exposure can be performed using this parallel light.

The light passing through the pinhole 53 may be converted into parallel light by the optical lens 54, and the parallel light may be used for exposure. The sunlight 57 is introduced as parallel light while the secondary light is shielded by the shield plate 55.
You may make it expose by parallel light.

[0019]

The exposure is carried out using the photomask 4 formed by providing the light transmitting portion 4a whose size is adjusted according to the spread of the parallel light due to the distance between the photomask 4 and the circuit formation surface of the circuit board 1. As a result, even if the distance between the circuit board 1 and the photomask 4 is large, it is possible to correct the spread of the parallel light due to this distance and perform exposure, and due to the large unevenness of the surface of the circuit board 1, It is possible to prevent the width dimension from becoming non-uniform.

Further, by exposing the photomask 4 by superimposing the photomask 4 in a plurality of steps according to the distance between the photomask 4 and the circuit formation surface of the circuit board 1, unevenness of the surface of the circuit board 1 can be reduced. Even if it is large, the distance between each photomask 4 and the circuit formation surface of the circuit board 1 can be made small, and the width dimension of the circuit 6 is prevented from becoming non-uniform due to the complicated unevenness of the surface of the circuit board 1. can do.

Further, when the photomasks 4 of a plurality of stages are simultaneously exposed, the light amount passing through the photomask 4 may be slightly reduced in the portions of the photomask 4 which are vertically overlapped, and the exposure amount may be non-uniform. However, among the photomasks 4 of a plurality of stages, an exposure mask 4 ′ provided by patterning the light transmitting portion 4 a on the photomask 4 of one stage is used, and light is not transmitted to the photomasks 4 of other stages. It is possible to prevent the exposure amount from becoming non-uniform by performing the exposure using the mask 4 ″, and by sequentially replacing the exposure mask 4 ′ and the light-shielding mask 4 ″ and performing the exposure a plurality of times.

When performing exposure with parallel light, collimator 51 uses parallel light having a higher degree of parallelism, laser light is used as parallel light whose light flux is expanded by optical lens 52, or it passes through pinhole 53. The parallel light having a high degree of parallelism can be obtained by using the reflected light as parallel light by the optical lens 54 or by introducing the sunlight 57 as parallel light while shielding the secondary light by the shield plate 55. High exposure can be performed.

Further, a plurality of flat plate-shaped photomasks 4 having the same exposure pattern are used, and the plurality of photomasks 4 are arranged at a predetermined interval so that the respective exposure patterns are aligned in the irradiation direction of the parallel light. The light non-transmissive portion of the exposure pattern on the side closer to the light source is formed by performing the exposure in the irradiation direction or by using the photomask 4 formed by providing the same exposure pattern on the front surface and the back surface, respectively. Even if the light wraps around 4a, this light is cut by the light non-transmissive portion 4a of the next exposure pattern, and the exposure can be performed with high accuracy.

[0024]

EXAMPLES The present invention will be described in detail below with reference to examples. 3 and 4 show one embodiment of the present invention. The circuit board 1 is formed by a molded product having a three-dimensional surface. For example, "Vectra C820" manufactured by Polyplastics Co., Ltd. is used as a resin, pre-dried 150 ° C., 8 hours or more, injection time 4 to 5 seconds, By performing injection molding under conditions of a mold temperature of 130 ° C. and a resin temperature of 310 ° C., as shown in FIG.
It can be created as shown in (a).

The circuit board 1 molded as described above is subjected to electroless plating such as electroless copper plating to form an electroless plating layer 2 on the entire surface of the circuit board 1 as shown in FIG. 3 (b). To do. Explaining an example of the electroless plating process,
50g of "Aesculin A-220" made by Okuno Yakuhin
/ Liter solution to remove oil and the like on the surface of the circuit board 1 by degreasing at 55 ° C for 5 minutes,
Then 70% with a 500 g / l solution of NaOH
The surface of the circuit board 1 is roughened in order to improve the adhesion of the plating by etching under conditions of 30 ° C. and 30 minutes. After removing the etched resin and filler by etching with hot water at 60 ° C for 2 minutes to completely remove the fine irregularities, a 50 ml / l solution of HCl (36%) is used for 2 minutes at room temperature. Neutralize strong alkali. Next, Okuno Yakuhin's "Condilyzer S"
40 with 150 ml / l solution of "P"
A conditioner treatment is performed under conditions of 5 ° C. for 5 minutes to improve the water wettability of the surface of the circuit board 1. Further, a 250 g / liter solution of “OPC-SALM” manufactured by Okuno Chemical Co., Ltd. and “OPC-80” manufactured by Okuno Chemical Co., Ltd. The catalyst application treatment is performed for 5 minutes at room temperature using a 40 ml / liter solution of "Cata M" to adsorb the palladium catalyst nuclei on the surface of the circuit board 1. And "OPC made by Okuno Yakuhin
-Activation treatment using a 100 ml / liter solution of "-500 Accele MX-1" and a 10 ml / liter solution of "OPC-500 Accele MX-2" manufactured by Okuno Chemical Industries, Ltd. at 40 ° C for 7 minutes. After reducing the palladium chloride to metallic palladium by the method, a 100 ml / liter solution of "OPC-750MA" manufactured by Okuno Chemical Co., Ltd., "OPC-750M manufactured by Okuno Chemical Co., Ltd."
By using 100 ml / liter solution of "B" and 2 ml / liter solution of "OPC-750MC" manufactured by Okuno Chemical Industries, electroless copper plating is performed at 22 ° C. for 7 minutes, and thereby copper is oxidized and reduced. The complex compound can be converted to metallic copper and deposited on the surface of the circuit board 1 to form the electroless plating layer 2 having a thickness of 0.5 μm on the entire surface of the circuit board 1. In addition, by performing the etching treatment for surface roughening using the NaOH solution as described above, it is possible to perform the method without using chromic acid.

After the electroless plating layer 2 is formed on the entire surface of the circuit board 1 as shown in FIG. 3B, as described above,
A photoresist 3 is applied over the entire surface as shown in FIG. 3 (c). A cationic electrodeposition resist is used as the photoresist 3, and the photoresist 3 is applied by electrodeposition coating. An example of the resist electrodeposition step will be described. First, 5% sulfuric acid is used for 15 seconds at room temperature and lactic acid (10-5-1-0.2) is used.
%) For 15 seconds at room temperature to pretreat the surface of the circuit board 1. Next, the circuit board 1 is dipped in an electrodeposition resist solution of "Eagle" manufactured by Shipley Co., Ltd., an electrode is inserted into the electrodeposition resist solution, the electroless plating layer 2 formed on the surface of the circuit board 1 is connected to a cathode, and the electrode is formed. Is connected to the anode and a direct current is passed between them,
The photoresist 3 made of an electrodeposition resist can be applied. Immersion can be performed for 5 seconds with shaking for 60 seconds, and the electrodeposition resist solution is adjusted to 22 ° C. for 50 seconds.
The electrodeposition coating is performed by energizing under the conditions of V and 40 seconds.

After the electrodeposition coating is performed as described above and the photoresist 3 is applied on the entire surface of the circuit board 1, a top coat is performed at room temperature and further dried at 80 ° C. for 5 minutes. Then, next, as shown in FIG.
As shown in (d), the photomask 4 is covered, and 600 mJ (1
(000 count) and irradiate parallel light from above the photomask 4 to expose, then remove the photoresist 4 and apply "Eagle developer" manufactured by Shipley Co., Ltd. to the surface of the circuit board 1 at 45 ° C. for 90 seconds. By spraying and developing under the conditions, the photoresist 3 in the circuit forming portion is dissolved and removed, and dried at 60 ° C. for 10 minutes.

Although exposure and development can be carried out in this manner, in the present invention, the flat photomask 4 has an exposure width depending on the distance between the circuit forming surface of the circuit board 1 and the photomask 4. The adjusted one is used. That is, when the surface of the circuit board 1 is covered with the photomask 4 as shown in FIG. 1A, the concave portion 9 in which the distance between the photomask 4 and the surface of the circuit board 1 becomes large.
At this point, the light transmitted through the light transmitting portion 4a of the photomask 4 spreads due to a diffraction phenomenon and also wraps around to a part of the back side of the light non-transmitting portion 4b. It increases as the distance between and increases. Therefore, in the present invention, as shown in FIG. 1B, the width of the portion of the light non-transmissive portion 4b of the photomask 4 corresponding to the concave portion 9 is widened, and the deeper the depth of the concave portion 9, the light non-transmissive portion 4b. The width of the light transmitting portion 4a is made wider by narrowing the width of the portion corresponding to the concave portion 9 and narrowing the deeper the concave portion 9, and Even if the parallel light transmitted through the transmissive portion 4a is diffracted by the concave portion 9 and spreads and spreads around to the back side of the light non-transmissive portion 4b, the sneak of the light is absorbed by the dimension in which the width of the light non-transmissive portion 4b is widened. In the recess 9 of the circuit board 1, the photoresist 3 can be exposed with the same exposure width as the other portions. Even with the circuit board 1 having the concave portion 9 having such a large step, it is possible to perform exposure with a uniform exposure width over the entire surface on which the circuit is formed. As a result, unexposed patterns having the same pattern as the circuit 6 are exposed. The width of the portion 3 becomes uniform and the width of the photoresist 3 to be dissolved and removed at the time of development becomes uniform, and the circuit 6 created by electroplating the electroless plating layer 2 in the dissolved and removed portion of the photoresist 3 is formed. As shown in FIG. 1C, it is possible to form a uniform width including the inside of the recess 9.

In the embodiment of FIG. 1, the case where the negative type photoresist 3 is used has been described, but when the positive type photoresist 3 is used, it becomes as shown in FIG. That is, in this case, the light transmitting portion 4a of the photomask 4 is not shown in FIG.
As shown in FIG. 2B, it is formed in the same pattern as the circuit 6 formed on the circuit board 1. However, as shown in FIGS. 2A and 2B, a portion of the light transmitting portion 4a corresponding to the concave portions 9a and 9b is formed. A photomask 4 having a narrower width and a narrower width dimension of the light transmitting portion 4a as the depths of the recesses 9a and 9b become deeper.
Parallel light transmitted through the light transmitting portion 4a is used to form the concave portions 9a, 9
Even if the light is diffracted at the portion b and spreads and goes around to the back side of the light non-transmissive portion 4b, the spread of this light is absorbed by the dimension of the light transmissive portion 4a which is narrowed, and even in the concave portions 9a and 9b of the circuit board 1. The photoresist 3 can be exposed with the same exposure width as the other portions. Even with the circuit board 1 having the recesses 9a and 9b having large steps, it is possible to perform exposure with a uniform exposure width over the entire surface of the circuit formation, and the photoresist is dissolved and removed during development. The width of 3 becomes uniform, and as shown in FIG. 2C, the circuit 6 can be formed to have a uniform width including the inside of the recesses 9a and 9b.

The relationship between the distance between the photomask 4 and the surface of the circuit board 1 and the width of the circuit 6 formed on the circuit board 1 is such that the width dimension of the light transmitting portion 4a of the photomask 4 is constant. This can be determined by measuring the width dimension of the circuit 6 when the circuit is formed by changing the distance between the surface of the circuit board 1 and the surface of the circuit board 1. For example, the width dimension of the light transmitting portion 4a of the photomask 4 is set to 200 μm, and
Relationship between the distance between the photomask 4 and the surface of the circuit board 1 and the width of the line 6 of the circuit 6 when parallel light is irradiated at an exposure amount of UV irradiation energy of 00 mJ / cm ² for exposure. Is as follows. (Distance between photomask 4 and surface of circuit board 1) (Line width of circuit 6) 0 mm → 199 μm 1.5 mm → 206 μm 3 mm → 220 μm 4.5 mm → 245 μm 6 mm → 268 μm 7.5 mm → 294 μm 9 mm → 318 μm 10.5 mm → 357 μm By obtaining such a relationship, the photomask 4 is correspondingly obtained.
The width of the light transmitting portion 4a is corrected to be narrower in accordance with the distance between the surface of the circuit board 1 and the surface of the circuit board 1, so that even if the distance between the photomask 4 and the surface of the circuit board 1 changes, a uniform line width The circuit 6 can be formed.

After the exposure and development are performed as described above to remove the photoresist 3 in the circuit forming portion to expose the electroless plating layer 2 in the circuit forming portion, the electroless plating layer 2 is energized to generate electricity. The circuit 6 can be formed by electroplating such as copper plating. An example of the electroplating step will be described. First, degreasing is performed using a 50 g / liter solution of “Aesculin” at 40 to 50 ° C. for 2 seconds, and then using a 50 g / liter solution of sulfuric acid at room temperature for 20 seconds. Pickled under the conditions. Then, using "Toprutina" having a composition of 80 g / liter of copper sulfate, 180 g / liter of sulfuric acid, and 50 mg / liter of chlorine ion as a plating bath, electroplating was performed at room temperature for 50 minutes, as shown in FIG.
As described above, the electroplating layer 5 is deposited with a thickness of 15 μm only on the exposed portion of the electroless plating layer 2.

After electroplating as shown in FIG. 4A, the electroless plating layer 2 is further energized to perform electronickel plating on the electroplating layer 5. Electro nickel plating is 18 of "ACNA B-40"
Milliliter / liter solution, 1 of "ACNA B-10"
Milliliter / liter solution, 270 g of nickel sulfate
/ Liter solution and 50 g / liter solution of nickel chloride are used as a plating bath, and electricity is applied under the conditions of 50 ° C., 3 A / dm ² and 25 minutes to deposit nickel plating on the electroplated layer 5 to a thickness of 5 μm. It can be done by

After nickel plating is performed in this way, the electroless plating layer 2 is further energized to perform electrogold plating on the nickel plating. The electro-gold plating uses "Temperex 401 (99.99%)" as a plating bath, and energizes it under the conditions of 65 ° C, 1 A / dm ² and 90 seconds,
It can be performed by depositing gold plating with a thickness of 0.5 μm on nickel plating.

After electroplating as described above, the photoresist on the surface of the circuit board 1 is treated by treating the circuit board 1 with "Eagle stripping solution" manufactured by Shipley at 55 ° C. for 1 minute. 3 is peeled off. Further, by using ammonium persulfate for 1 minute at 40 ° C. to perform soft etching, the unnecessary electroless plating layer 2 other than the circuit forming portion is dissolved and removed from the surface of the circuit board 1 and washed with pure water at room temperature for 15 seconds. And then 10 at 60 ℃
Dry for minutes. In this manner, as shown in FIG. 4C, the pattern of the circuit 6 including the electroless plating layer 2, the electroplating layer 5, and the nickel and gold plating layer 7 can be formed. Angle 70 degrees, uneven step 8 mm, circuit pattern line / space = 2
The three-dimensional circuit board capable of wire bonding of 00 μm / 200 μm can be produced.

After forming the circuit 6 as shown in FIG. 4C, a component 18 such as an electronic component such as an LSI is formed.
4 (d) and FIG. 5 by mounting a wire and bonding a gold wire or the like between the circuit 6 and the component 18 by wire 19.
The component 18 can be mounted on the circuit board 1 as shown in FIG. 6 and 7 show another embodiment of the present invention. This embodiment is mainly applied to the circuit board 1 in which the three-dimensional surface is formed in a plurality of stages as shown in FIG. 6 (a). Similarly to the case of FIG. 3B, the electroless plating layer 2 is formed on the surface of the circuit board 1 as shown in FIG. 6B.
Then, the photoresist 3 is applied to the surface of the circuit board 1 as shown in FIG. 6C in the same manner as in the case of FIG. In this embodiment, exposure is performed as shown in FIG.
As shown in (d), the flat photomask 4 is divided into a plurality of stages, and the photomasks 4 are superposed on the respective stages 1a and 1b on the surface of the circuit board 1, and the photomask 4 shown in FIG.
Similar to the case of (d), it is performed by irradiating parallel light from above the photomask 4. here,
When one flat photomask 4 is used, it is overlaid on the upper step 1a. However, in this case, the space between the recess 9b formed in the lower step 1b and the photomask 4 is large. Become. On the other hand, as shown in FIG. 6D, the photomask 4 is divided into a plurality of stages and each stage 1a, 1b of the circuit board 1 is divided.
If they are overlapped with each other, the distance between the concave portions 9a and 9b and the photomasks 4 and 4 becomes small, and the distance between the photomask 4 and the circuit forming surface of the circuit board 1 becomes small. It can be exposed.

Since the distance between the photomask 4 and the circuit forming surface of the circuit board 1 can be reduced in this manner, the photomask 4 shown in FIG. 31B, which has been conventionally used, is used. Even if it is used as it is, the exposure can be performed with high accuracy. Of course, as the photomask 4, as shown in FIGS. 1A and 1B and FIGS. 2A and 2B, the spread of the parallel light accompanying the space between the photomask 4 and the circuit formation surface of the circuit board 1. If the photomask 4 having the light transmitting portion 4a whose size is adjusted according to the above is used, the exposure accuracy can be further improved.

When the photomask 4 is divided into a plurality of stages and used, the photomask 4A may be partially overlapped with only the deep recess 9b. That is, as shown in FIG. 8, a photomask 4A is formed according to the planar shape of the deep recess 9b of the circuit board 1, and the photomask 4 has a light transmitting portion 4c (which transmits light according to the shape of the photomask 4A). The portion between the broken lines in FIG. 8) is formed. Of course, these photomasks 4 and 4A are formed with a light transmitting portion 4a and a light non-transmitting portion 4b for forming a circuit in a pattern shape. Then, as shown in FIG. 9, the photomask 4A is superposed on the deep recess 9b of the circuit board 1 and the photomask 4 is superposed on the step 1a on the circuit board 1. At this time, the light transmitting portion 4c of the photomask 4 is changed to the photomask 4A.
The photomask 4 and the photomask 4A are aligned and arranged so as to face each other in the irradiation direction of the parallel light. The photomask 4A has an outer shape formed in accordance with the planar shape of the recess 9b. The photomask 4 can be positioned by placing the photomask 4A in conformity with the shape of 9b, but the photomask 4 is aligned using the circuit board fixing jig 11 in the embodiment of FIG. That is, the circuit board fixing jig 11 is formed by forming a recess 20 on the upper surface that matches the planar shape of the circuit board 1. The circuit board fixing jig 11 is provided with screw holes 21 on the upper surface of the end portion of the circuit board fixing jig 11. Positioning holes 22 are provided at the four corners of the mask 4, and the circuit board 1 is set in the circuit board fixing jig 11 by fitting the circuit board 1 into the recesses 20. Also, the fixing screws 23 are passed through the positioning holes 22. The photomask 4 is set in a state of being positioned on the circuit board fixing jig 11 by being screwed into the screw holes 21, and the circuit board 1 and the photomask 4 are respectively positioned with respect to the circuit board fixing jig 11 in this way. Thus, the circuit board 1 and the photomask 4 can be positioned via the circuit board fixing jig 11. still,
The positioning of the photomask 4 is performed by the fixing screw 23 as shown in FIG.
Other than the method using a jig such as FIG.
4, FIG. 15, FIG. 16, FIG. 18, FIG. 19, FIG. Then, by positioning the photomask 4 and the photomask 4A in this manner, the photomask 4 and the photomask 4A can be aligned with each other.

After the photomask 4 and the photomask 4A are superposed on the circuit board 1 as described above, parallel light is irradiated to perform exposure. In the photomask 4 portion, the light transmitting portion 4
a and the light non-transmissive portion 4b can be exposed, and at the photomask 4A portion, the light transmitted through the light transmissive portion 4c of the photomask 4 causes the light transmissive portion 4a and the light non-transmissive portion 4b of the photomask 4A to be exposed. You can perform exposure with.

FIGS. 10 and 11 show another example in which exposure is performed using a flat plate-shaped photomask 4 divided into a plurality of steps. In this example, only one step is used as the photomask 4 for the light transmitting portion 4a. Is used for the exposure, and the photomasks 4 on the other stages are exposed by using a light-shielding mask 4 ″ that does not transmit light. That is, in FIG. Light transmission part 4a
And an exposure mask 4'formed by providing a light non-transmissive portion 4b
And a light-shielding mask 4 ″ whose entire surface is formed as a light non-transmissive portion 4b (FIG. 10 (b), the light non-transmissive portion 4b is indicated by diagonal lines in FIG. 11 (b)), as shown in FIG. 10 (a). The exposure mask 4'is superposed on the upper step 1a of the circuit board 1 and the light shielding mask 4 "is superposed on the lower step 1b, and parallel light is irradiated in this state. At the time of this first exposure, light does not pass through the light-shielding mask 4 ″ and is transmitted only through the light-transmitting portion 4 a of the exposure mask 4 ′, so that as shown in FIG. Only part of the surface is exposed (Fig. 10 (c),
In FIG. 11C, the resist exposure portion 3a is indicated by cross hatching. Next, a light-shielding mask 4 ″ as shown in FIG.
11A, a light-shielding mask 4 ″ is placed on the upper step 1a of the circuit board 1 and an exposure mask 4 ′ is placed on the lower step 1b as shown in FIG. During the second exposure, the light does not pass through the light-shielding mask 4 ″ and only passes through the light-transmitting portion 4a of the exposure mask 4 ′, so that the circuit shown in FIG. The other portion of the substrate 1 is also exposed, and the entire surface of the circuit board 1 can be exposed together with the first exposure. In the embodiment of FIGS. 10 and 11, the photomask 4 is divided into two stages, so that the exposure is performed twice. However, when the photomask 4 is divided into three stages, the exposure is repeated three times. The exposure is performed a number of times according to the number of divisions of the photomask 4. Then, after performing the exposure as described above, the development is performed and the processing for forming the circuit is performed, whereby the circuit 6 can be three-dimensionally formed on the surface of the circuit board 1 as shown in FIG.

When the exposure masks 4'are used as the photomasks 4 of a plurality of stages to perform exposure at a time without performing the steps shown in FIGS. In order to prevent light from entering due to diffraction or the like, the adjacent photomasks 4 need to be overlapped at their end portions in the irradiation direction of the parallel light as described later. Light transmitting portion 4 of mask 4
Since the parallel light passes through a, the amount of light is slightly reduced as compared with the other portions passing through the light transmitting portion 4a of the one photomask 4, and as a result, the exposure amount becomes non-uniform, which hinders circuit formation. May occur, and it may be difficult to form a high-density fine pattern. For this reason, in the embodiment of FIGS. 10 and 11, the exposure is performed a number of times corresponding to the number of divisions of the photomask 4 to enable the formation of a high-density fine pattern.

In the embodiment shown in FIGS. 10 and 11, as the exposure mask 4 ', like the photomask 4 shown in FIG. 1B, the portions of the light non-transmissive portion 4b corresponding to the recesses 9a, 9b. The width of the light non-transmissive portion 4b is increased as the depth of the recesses 9a and 9b is increased, so that the width of the light transmissive portion 4a is reversed to that of the portions corresponding to the recesses 9a and 9b. The width is narrowed and the recesses 9a and 9b are formed so that the deeper they are, the narrower the recesses 9a and 9b are formed.
Even if the light diffracts and spreads at the portions a and 9b and wraps around to the back side of the light non-transmissive portion 4b, the wraparound of this light is prevented by the light non-transmissive portion 4b.
The width of the concave portion 9 of the circuit board 1 is absorbed by the increased width.
Also in a and 9b, the photoresist 3 can be exposed with the same exposure width as the other portions. Although FIGS. 10 and 11 show examples in which the negative type photoresist 3 is used, when the positive type photoresist 3 is used, the same exposure as that of the photomask 4 shown in FIG. 2B is performed. The mask 4'may be used. When the distance between the exposure mask 4'and the recesses 9a and 9b is small, the photomask 4 of FIG. 31 (b) which has been conventionally used can be used as it is as the exposure mask 4 '. When the photomasks 4 are overlapped as in each of the above-described embodiments, it is necessary to align the light transmitting portions 4a and the light non-transmitting portions 4b formed in the pattern shape of the photomask 4 with the irregularities on the surface of the circuit board 1. . 13 and 14 show an embodiment in which the photomask 4 is aligned and superposed on the circuit board 1, and an alignment portion is simultaneously formed on the upper surface of the circuit board 1 when the circuit board 1 is resin-molded. 10 is integrally molded. The alignment portion 10 can be formed as a convex portion, but in this embodiment, as shown in FIGS. 13A and 14A, it is formed as a concave portion having a diameter of 2 mm and a depth of about 3 mm. The photomask 4 is also shown in FIG.
As shown in FIG. 3A, two alignment holes 14 having a diameter of about 2 mm are provided corresponding to the alignment portion 10. Then, after the photoresist 3 is applied to the circuit board 1 in the above-described process, the alignment portion 10 of the circuit board 1 and the alignment hole 14 of the photomask 4 are aligned as shown in FIG. Photomask 4 is placed on top of the
The photomask 4 can be positioned by inserting the pin 15 into the alignment portion 10 through the alignment hole 14 as shown in FIGS. 14B and 14C, and the alignment portion 10 of the circuit board 1 can be used as a reference. The photomask 4 can be aligned and fixed to the circuit board 1. In this way, the photomask 4 is aligned and superposed on the circuit board 1, and then exposed.

In the embodiment shown in FIG. 15, the alignment portion 10 is formed as a convex portion.
For example, 0 can be formed into a prismatic shape having a 2 mm square and a height of 5 mm. In addition, the photomask 4 is formed with a positioning hole 14 having a square hole of 2 mm square.
No. 4 is reinforced by caulking and fitting the metal reinforcing metal fitting 16 as shown in FIG. And FIG.
As shown in (b), the alignment portion 10 is inserted into the alignment hole 14 for positioning, and the photomask 4 is superposed on the circuit board 1 coated with the photoresist 3.
Circuit board 1 based on the alignment portion 10 of the circuit board 1
The photomask 4 can be aligned and fixed to the.

FIGS. 16 and 17 show another embodiment of the alignment of the photomask 4, in which the circuit board fixing jig 11 has a recess 2 on the upper surface which conforms to the planar shape of the circuit board 1.
0 is provided, and a pin hole 24 is provided on the upper surface of the end portion of the circuit board fixing jig 11. Further, on the upper side of the photomask 4, there is attached a support rod 12 which is formed by bending an L-shaped metal rod having a diameter of about 2 mm. As shown in FIG. 17 (a), the support bar 12 is formed by inserting the male screw portion at the tip of the vertical piece 12a into the end portion of the photomask 4 and by attaching a pair of nuts 25, 25 screwed to the male screw portion to the front and back of the photomask 4. By being sandwiched, it is detachably attached to the photomask 4. This support rod 12 is shown in FIG.
As shown in FIG. 7 (a), the horizontal piece 12b is attached so as to project to the outside of the photomask 4. In this embodiment, two support rods 12 are attached to each photomask 4. As shown in FIG. 17B, a fixing piece 26 is provided at the tip of the lateral piece 12b of the support rod 12, and a pin passing hole 27 is formed in the fixing piece 26.

Then, the circuit board 1 coated with the photoresist 3 is fitted into the recess 20 to set the circuit board 1 on the circuit board fixing jig 11 in a positioned state, and the pin holes of the circuit board fixing jig 11 are set. The photomask 4 is superposed on the circuit board 1 with the pin through holes 27 of the support rod 12 aligned with the pin 24, and the pins 15 are inserted into the pin holes 24 through the pin through holes 27 to place the photomask 4 on the circuit board. Set in the fixed jig 11 in a positioned state. By positioning the circuit board 1 and the photomask 4 with respect to the circuit board fixing jig 11 in this manner, the circuit board 1 and the photomask 4 can be positioned via the circuit board fixing jig 11. The photomask 4 can be fixed to the substrate 1 in the aligned state. In this way, the photomask 4 is aligned and superposed on the circuit board 1, and then exposed.

Further, when the photomask 4 is superposed on the surface of the circuit board 1 in a plurality of stages, as shown in FIG.
10 (a), 11 (a), 14 (c), 16
As shown in (a), it is preferable that the photomasks 4 adjacent to each other are arranged such that their end portions overlap each other in the vertical direction, that is, in the irradiation direction of the parallel light. By providing the overlapping portions at the step portions of the adjacent photomasks 4 in this way, it is possible to prevent light from entering from between the end portions of the photomask 4 due to diffraction or the like. The overlapping width of the end portion of the photomask 4 is determined in consideration of the parallelism of light, the degree of diffraction, the distance (step) between the top and bottom of the photomask 4, and the like. Incidentally, FIG.
(D), FIG. 10 (a), FIG. 11 (a), FIG. 14 (c),
In each embodiment of FIG. 16A, the photomask 4 is divided into a plurality of sheets and divided into a plurality of stages so as to be superposed on the circuit board 1. However, by folding one photomask 4 into a plurality of stages. You may make it divide and may overlap on the circuit board 1.

When arranging the photomasks 4 so that the ends of the adjacent photomasks 4 are overlapped with each other as described above, the photomasks 4 are positioned and overlapped with each other on the circuit board 1 while the photomasks 4 are aligned with each other. Need to do so. FIG. 18 shows an example thereof, and FIG.
As shown in (a), two concave holes 28 having a diameter of 2 mm and a depth of about 2 mm are formed on the upper surface of the circuit board 1. The recessed hole 28 can be provided by simultaneous molding when the circuit board 1 is molded with resin, or can be processed and provided after molding. Further, the photomasks 4 arranged adjacent to each other are shown in FIG.
As shown in (b), the photomasks 4 are joined and fixed at two locations by the joining jig 29 in a state where the end portions of the photomasks 4 overlap each other. The coupling jig 29 is formed by bolts 29a and nuts 29b having a diameter of about 2 mm, and holes are provided at the overlapping end portions of the photomasks 4 so that the bolts 29a can pass through.
The nut 29b is fixed to the bolt 29a by screwing. Then, after the photoresist 3 is applied to the circuit board 1 in the above-described process, the adjacent photomasks 4 are aligned by the joining jigs 29 and the ends are overlapped and joined together, and the joining jigs are joined together. 18 is inserted into the recess 28 of the circuit board 1 and the photomasks 4 are aligned with the circuit board 1.
As shown in (c), each photomask 4 can be fixed to the circuit board 1.

FIG. 19 (c) shows another example of the connecting jig 29, which has a diameter of 3.5 mm.
A bolt portion 29d having a diameter of about 2 mm is formed so as to project from the upper and lower ends of the spacer portion 29c, and the bolt portion 29d is passed through the hole provided at the overlapping end portion of each photomask 4 to reach each bolt portion 29d. By screwing the nut 29b, the photomask 4 is sandwiched between the nut 29b and the end surface of the spacer portion 29c, and the spacer portion 29 is formed.
With a predetermined distance between both photomasks 4 by c, the coupling jigs 29 with the ends of the photomasks 4 overlapped with each other.
Thus, the two parts are joined and fixed as shown in FIG. Similarly, this one is also shown in FIG.
In the state where the bolts 29d at the lower end of the coupling jig 29 are inserted into the recessed holes 28 of the circuit board 1 and the photomasks 4 are aligned with respect to the circuit board 1 as shown in FIG. It can be fixed.

FIG. 20 shows another embodiment in which adjacent photomasks 4 are positioned and overlapped on the circuit board 1 in a aligned state. A recess 41 having the same shape as the planar shape of the circuit board 1 is formed on the upper surface. FIG. 20B, which is formed by the tray 42 provided and a frame body 43 that matches the outer peripheral shape of the tray 42.
The exposure jig 44 as described above is used. A screw hole 45 is formed on the upper surface of the outer peripheral portion of the tray 42 of the exposure jig 44.
However, through holes 46 are provided in the frame body 43 at positions corresponding to the screw holes 45. Then, the circuit board 1 coated with the photoresist 3 in the above-described process is fitted into the recess 41 to expose the exposure jig 44 as shown in FIG.
The circuit board 1 is set in the tray 42 in a positioned state, and one photomask 4 of the pair of adjoining photomasks 4 is placed on the circuit board 1. A screw through hole 47 is formed in an end portion of the photomask 4, and the photomask 4 is mounted on the circuit board 1 via the tray 42 by aligning the screw through hole 47 with the screw hole 45 of the tray 42.
Can be positioned. In the embodiment of FIG. 20, since the circuit board 1 is provided with the projecting portion 1c which largely projects as shown in FIG. 20 (a), the opening 48 provided in the photomask 4 should be inserted into this projecting portion 1c. The photomask 4 can also be positioned on the circuit board 1 by the above. Next, align the through hole 46 with the screw hole 45, and then, as shown in FIG.
As described above, the frame body 43 is superposed on the tray 42 via the photomask 4, and the other photomask 4 of the pair of adjoining photomasks 4 is superposed on the frame body 43. A screw through hole 47 is also formed in the end portion of the other photomask 4, and the photomask 4 is attached to the frame body 43 and the tray 42 by aligning the screw through hole 47 with the through hole 46 of the frame body 43. It can be positioned via the circuit board 1. After this, as shown in FIG.
Fixing screw 49 to the screw through hole 47 of and the through hole 46 of the frame 43.
By screwing the fixing screw 49 into the screw hole 45 of the tray 42, the frame body 43 can be coupled to the tray 42 and each photomask 4 can be fixed.

After the exposure and the development as described above, the electroless plating layer 2 is energized to perform electroplating or the like in the same manner as in FIG. 4), an electroplating layer 5 is further provided, and a plating layer 7 such as nickel plating or gold plating is further provided in the same manner as in the case of FIG. 4B, and then the photoresist is formed in the same manner as in the case of FIG. 4C. The pattern of the circuit 6 including the electroless plating layer 2, the electroplating layer 5 and the plating layer 7 as shown in FIG. It can be formed. Then, after forming the circuit 6 in this way, a component 18 such as an electronic component is mounted and a gold wire or the like is bonded to the wire 19 between the circuit 6 and the component 18, as shown in FIG. Thus, the component 18 can be mounted on the circuit board 1.

In each of the embodiments shown in FIGS. 1 to 20,
The parallel light is used for the exposure. As the parallel light, the collimator 51 can be used to increase the parallelism. FIG. 21 shows an example thereof. A photomask photo in which the primary parallel light L ₁ is passed through the collimator 51 and the non-parallel light is cut off to increase the parallelism, and the secondary parallel light L ₂ is superposed on the circuit board 1. Irradiation is performed from above the mask 4. As the primary parallel light L ₁ , light emitted from a mercury lamp may be condensed by a mirror and parallelized through a parallel lens. Further, as the collimator 51, any known one, for example, one using a cylinder or a double grid can be used. When light is exposed to the collimator 51, it is preferable that the collimator 51 be rotated while being rotated in a plane perpendicular to the irradiation direction so that the exposure amount is uniform. In this way, the secondary parallel light L whose parallelism is increased by the collimator 51
By performing exposure using ₂ , even if the distance between the circuit forming surface of the circuit board 1 and the planar photomask 4 is large, it is possible to reduce the spread of parallel light due to this distance. It is possible to prevent the width dimension of the circuit from becoming non-uniform even if it is formed on a three-dimensional surface with large unevenness, and it is possible to form the circuit with a uniform width and form the circuit on high-density wiring. It will be.

FIG. 22 shows an embodiment in which exposure is performed by using a plurality of photomasks 4, and a plurality of flat plates (planar) (in the embodiment shown in the drawing, 2) are formed.
On each of the photomasks 4), a light transmitting portion 4a and a light non-transmitting portion 4b are formed with the same exposure pattern. One photomask 4 of the plurality of photomasks 4 is overlaid on the circuit board 1 as shown in FIG. 22A, and another photomask 4 is overlaid on the photomask 4 at a predetermined constant interval. In this state, parallel light is irradiated to perform exposure. At this time, the photomasks 4 are overlapped by aligning the exposure patterns so that the light transmitting portions 4b accurately face each other in the irradiation direction of the parallel light. When a plurality of photomasks 4 are overlapped with each other at intervals as described above, as shown in FIG. 22B, even when light wraps around the back side of the light non-transmissive portion 4b of the first photomask 4, The circulated light is blocked by the light non-transmissive portion 4b of the second photomask 4 formed in the same pattern as the light non-transmissive portion 4b, so that the parallel light spreads and the parallel light of the circuit board 1 is spread. Irradiation of the UV-sensitive photoresist 3 can be reduced. Therefore, even if the distance between the circuit forming surface of the circuit board 1 and the photomask 4 is large, the spread of the parallel light can be reduced.
Even when the unevenness is large, it is possible to prevent the width dimension of the circuit from becoming nonuniform, and it is possible to form the circuit with a uniform width and form the circuit on the high-density wiring.

Next, an embodiment in which the light absorbing material 58 is applied to the light non-transmissive portion 4b of the photomask 4 will be described. First, as shown in FIG. 23A, a positive dry film is formed on the entire upper surface (the surface on which parallel light is incident) of the photomask 4 on which an exposure pattern is formed by providing the light transmitting portions 4a and the light non-transmitting portions 4b. 23 (c) is applied, and the photomask 4 is exposed to the upper side as shown in FIG. 23 (b). Then, the photoresist 59 in a portion corresponding to the non-light-transmitting portion 4b which is not exposed is shown in FIG. 23 (c). ) And remove it. Next, as shown in FIG. 23D, the light absorbing material 58 such as carbon is sprayed to remove the photoresist 59, and then the light absorbing material 58 is applied to the surface of the photomask 4 at the portion where the photoresist 59 is removed, and then the photoresist 59 is removed. As a result, the light absorbing material 5 is applied to the light non-transmissive portion 4b as shown in FIG.
The photomask 4 coated with 8 can be obtained.

Then, as shown in FIG. 24, the light absorbing material 58
The photomask 4 coated with is laminated on the circuit board 1 so that the light absorbing material 58 faces the parallel light irradiation side, and the exposure pattern is aligned so that the light non-transmissive portion 4b exactly faces the parallel light irradiation direction. Then, the photomask 4 not coated with the light absorbing material 58 is superposed on the photomask 4 at a predetermined constant interval, and in this state, parallel light is irradiated to perform exposure. In the embodiment shown in FIG. 24, the light from the light source 60 is converted into parallel light by the optical lens 61 for exposure. And in this one, the first photomask 4
The light circling to the back side of the light non-transmissive portion 4b is blocked by the light non-transmissive portion 4b of the second photomask 4, but the light non-transmissive portion 4b of the second photomask 4 is blocked. Since the light absorbing material 58 is applied to the surface, it is possible to completely prevent the circulated light from being absorbed by the light absorbing material 58 and reaching the photoresist 3 of the circuit board 1. In the embodiment of FIG. 24, the second photomask 4
And a circuit forming surface of the circuit board 1 are denoted by a, the spacing between the photomasks 4 is denoted by b, and the spacing between the optical lens 61 serving as a parallel light source and the first photomask 4 is denoted by c,
The parallelism changes by changing the distance b between b and c, but the parallelism increases as the distance b increases.

In the embodiment shown in FIG. 25, exposure is performed using the photomask 4 formed by providing the same exposure pattern on the front surface and the back surface, respectively. That is, the photomask 4 is formed by disposing the light non-transmissive portions 4b on the front surface and the back surface of the light-transmissive thick mask 62 so as to face each other in the same pattern. A low material is used to cut off the reflected light. Then, when this photomask 4 is overlapped on the circuit board 1 as shown in FIG. 25A and exposed by performing parallel light irradiation, as shown in FIG. Even if light wraps around on the back side of the transmissive portion 4b, the wraparound light is absorbed and blocked by the back light non-transmissive portion 4b formed in the same pattern as the front light non-transmissive portion 4b. Therefore, it is possible to reduce the spread of the parallel light and the irradiation of the photoresist 4 on the circuit board 1. Therefore, even if the distance between the circuit forming surface of the circuit board 1 and the photomask 4 is large, the spread of the parallel light can be reduced, and the unevenness of the circuit board 1 is large and the circuit forming surface and the photomask 4 are large. Even if there is a large space between the circuit and the circuit, it is possible to avoid unevenness in the width dimension of the circuit, and it is possible to form the circuit with a uniform width and form the circuit on high-density wiring. . here,
The parallelism of the parallel light can be adjusted by the thickness of the transparent mask 62 of the photomask 4 and the distance between the mask 62 and the circuit forming surface of the circuit board 1. The parallelism increases as the thickness of the mask 62 increases. It will be high.

Next, the manufacture of the photomask 4 will be described. First, a thick light-transmissive film as shown in FIG. 26A is used as a mask 62, and a photoresist such as a dry film is used as shown in FIG. 59 is patterned and masked, and then a light absorbing material 58 having a low light reflectance such as carbon is sprayed as shown in FIG. 26 (d) to spray the surface of the mask 62 at a portion not masked by the photoresist 59. After applying the light absorbing material 58 on the mask 6 and removing the photoresist 59, the light non-transmitting portion 4b is masked by the light absorbing material 58 as shown in FIG.
It is possible to obtain the photomask 4 provided on the front surface and the back surface of No. 2.

Further, when performing exposure using parallel light as in each of the above-described embodiments, the laser light 56 can be made into parallel light by expanding the light flux using the optical lens 52, and exposure can be performed with this parallel light. . FIG. 27 shows an example thereof, in which the output intensity of the laser light 56 such as an Ar laser having a wavelength of 360 nm and having a uniform output distribution is first made uniform by using the filter 63. Next, the laser light 56 having this uniform intensity distribution is converted into parallel light by expanding the light flux using the optical lens 52. In the embodiment of FIG. 27, the optical lens 52
As the light diffusion lens 52a and the parallel lens 52b,
First, the laser light 56 is passed through the light diffusion lens 52a to spread the laser light 56, and then the spread laser light 56 is passed through the parallel lens 52b to be a parallel light. Then, the ultraviolet light-sensitive photoresist 3 of the circuit board 1 is exposed through the planar photomask 4 with parallel light having this uniform intensity distribution. Although the laser light 56 is a light beam having a high degree of parallelism, it is difficult to directly irradiate the laser light 56 to expose the entire surface of the circuit board 1 because it is difficult to obtain a large area of the light flux. By using the optical beam from the optical lens 52 to expand the light beam as parallel light, it is possible to perform exposure with parallel light having a high degree of parallelism by the laser light 56. Therefore, even if the distance between the circuit forming surface of the circuit board 1 and the photomask 4 is large, the spread of the parallel light is reduced, and even if the circuit board 1 has large irregularities, the width dimension of the circuit becomes uneven. This can be avoided, and it becomes possible to form a circuit in a high-density wiring by forming the circuit with a uniform width.

When performing exposure using parallel light, the light that has passed through the pinhole 53 is passed through the optical lens 54.
It is also possible to make parallel light with and perform exposure with this parallel light. FIG. 28 shows an example thereof. First, scattered light 64 of uniform intensity including light having a wavelength necessary for the exposure of the photoresist 3 of the ultraviolet-sensitive type (light in the ultraviolet range or the like) is sent to the mercury lamp 67 or the like. It is irradiated from the light source and condensed by the condenser lens 65. The distance between the condenser lens 65 and the pinhole 53 provided on the light shield plate 66 is set to the focal length of the wavelength of light (for example, 360 nm) required for exposure in the condenser lens 65, The light condensed by the condenser lens 65 is collected in the pinhole 53 and passes through. Then, the light enters the optical lens 54 formed of a parallel lens using the pinhole 53 as a point light source, is converted into parallel light, and exposure can be performed with this parallel light. The distance between the optical lens 54 and the pinhole 53 is
Is set to the focal length of the wavelength of the light necessary for the exposure in, and the light from the pinhole 53, which serves as a point light source, is converted into parallel light with high parallelism by the optical lens 54. It is possible to perform exposure with highly parallel light. Therefore, even if the distance between the circuit forming surface of the circuit board 1 and the photomask 4 is large, the spread of the parallel light is reduced, and even if the circuit board 1 has large irregularities, the width dimension of the circuit becomes uneven. This can be avoided, and it becomes possible to form a circuit in a high-density wiring by forming the circuit with a uniform width.

When performing the exposure using the parallel light, it is possible to perform the exposure using the sunlight 57. The sunlight 57 is a parallel light having a high degree of parallelism because it is considered to be a point light source at infinity, but it cannot be used as it is as a parallel light source because secondary light 73 such as reflected light exists on the earth. Therefore, by introducing the sunlight as parallel light while shielding the secondary light 73 by the shielding plate 55, it becomes possible to perform exposure with the parallel light of this sunlight. FIG. 29 shows an example thereof,
The light-shielding plate 55 is made of a light-impermeable cylinder or the like, and the light-shielding plate 5
A shutter 69 is provided on the inner circumference of 5. The exposure table 70 is supported by the sun tracking device 71 so that the tilt angle can be freely adjusted, and the circuit board 1 on which the planar photomask 4 is stacked is placed on the exposure table 70 and the light shielding plate is provided. 55 is set on the exposure table 70, and the circuit board 1 is covered with the light shielding plate 55. At this time, the shutter 69 is closed, and the circuit board 1 is covered with the light shielding plate 55 on the periphery and is also shielded from light by the shutter 69. Therefore, light does not act on the photoresist 3 provided on the circuit board 1. Then, the sun tracking device 71 is operated so that the incident angle of the sun light 57 from the sun 72 to the photomask 4 becomes vertical, and the tilt angle of the exposure table 70 is adjusted.
When opened, the sunlight 71 entering from the opening at the upper end of the light shielding plate 55 facing the sun 72 passes through the shutter 69,
The photoresist 3 on the circuit board 1 from above the photomask 4
Can be exposed. The secondary light 73 such as reflected light is blocked by the light shielding plate 55 and does not reach the circuit board 1. Therefore, the exposure can be performed only by the sunlight 57 that is parallel light. An exposure amount counter 74 is provided below the shutter 69 inside the light shielding plate 55 to measure the exposure amount after the shutter 69 is opened. When the target exposure amount is reached, the shutter 69 is released.
Is closed. Here, an ultraviolet photosensitive resist can be used as the photoresist 3, but since the sunlight 57 uniformly contains light in a wide wavelength range,
It is also possible to use a resist that is sensitive to wavelengths other than ultraviolet light. Since the exposure can be performed with the sunlight 57 having a high degree of parallelism, the spread of the parallel light is reduced even if the distance between the circuit formation surface of the circuit board 1 and the photomask 4 is large, and the circuit board 1 Even when the unevenness of the circuit is large, it is possible to prevent the circuit from having a non-uniform width dimension, and it is possible to form the circuit with a uniform width and form the circuit on high-density wiring. .

[0059]

As described above, the present invention provides a photomask having a light-transmitting portion whose size is adjusted according to the spread of parallel light with the distance between the photomask and the circuit forming surface of the three-dimensional circuit board. Since the exposure is performed using the circuit board, even if the distance between the circuit board and the photomask is large, it is possible to perform the exposure by correcting the spread of the parallel light due to this distance, and when the unevenness of the circuit board is large. However, it is possible to prevent the width dimension of the circuit from becoming non-uniform, and it becomes possible to form the circuit with a uniform width and form the circuit in high-density wiring.

Further, according to the present invention, since the photomask is divided into a plurality of stages and the photomasks are overlapped for exposure in accordance with the distance between the photomask and the circuit formation surface of the circuit board, the unevenness on the surface of the circuit board is Even if it is complicated, the distance between each photomask divided into multiple stages and the circuit formation surface of the circuit board can be reduced, and the exposure width does not differ due to the large unevenness of the surface of the circuit board. It is possible to avoid non-uniformity, and it becomes possible to form a circuit with a uniform width to form a circuit on high-density wiring.

As described above, when performing exposure with a plurality of photomasks, as a photomask, light transmission is performed with the dimensions adjusted according to the spread of parallel light with the distance between the photomask and the circuit formation surface of the circuit board. By using a photomask having a portion formed therein, the exposure width can be made more uniform, and a circuit can be formed in high-density wiring with high accuracy.

As the above-mentioned resin-molded three-dimensional circuit board, one in which a concave portion or a convex portion is integrally molded at the time of resin molding to provide an alignment portion is used, and the photomask is aligned by the alignment portion. By stacking on the circuit board, the irregularities on the surface of the circuit board and the pattern of the photomask can be accurately corresponded, and the three-dimensional circuit can be accurately formed on the circuit board.

Further, the circuit board is positioned and set on the circuit board fixing jig, and the photomask is aligned with the circuit board by connecting the supporting rod detachably attached to the photomask to the circuit board fixing jig. Even if the photomask is overlaid on the circuit board by using the method, the unevenness of the surface of the circuit board and the pattern of the photomask can be accurately corresponded, and the three-dimensional circuit can be accurately formed on the circuit board. .

Further, if the photomasks are arranged so that the ends of adjacent photomasks of the photomasks in a plurality of stages overlap in the irradiation direction of the parallel light, the light enters from between the ends of the adjacent photomasks. Therefore, even if the photomask is divided into a plurality of stages, it is possible to perform exposure without defective light leakage. In this way, when arranging the photomasks so that the ends of the adjacent photomasks overlap each other in the irradiation direction of the parallel light, the photomasks can be aligned in the overlapping portion. It is possible to accurately form a three-dimensional circuit on the circuit board by eliminating the mutual positional displacement.

Further, when exposure is performed simultaneously with a plurality of photomasks, the amount of light passing through the photomask in the overlapping portions of the photomasks may be slightly reduced as compared with the other portions, and the exposure amount may become uneven. However, of the photomasks of multiple stages, an exposure mask in which a light-transmitting portion is patterned on one photomask is used, and the photomasks of the other stages are exposed using a light-shielding mask that does not transmit light. If the exposure mask and the light-shielding mask are exchanged and the exposure is performed multiple times, the exposure can be performed as many times as the number of steps of the photomask, and the exposure amount can be made uniform to form a high-density fine pattern. It will be possible.

Further, when performing exposure with parallel light, parallel light whose parallelism is increased by a collimator is used, or laser light is used as parallel light whose light flux is expanded by an optical lens, and further passed through a pinhole. By using light as parallel light with an optical lens, or by introducing sunlight as parallel light while blocking the secondary light with a blocking plate, highly accurate parallel light exposure is possible. Even if the distance between the circuit board and the photomask is large, the circuit width can be formed uniformly and a high-density fine pattern can be formed.

Further, a plurality of flat plate-shaped photomasks on which the same exposure pattern is formed are used, and a plurality of photomasks are arranged at predetermined intervals so that the exposure patterns are aligned in the parallel light irradiation direction. The light non-transmissive part of the exposure pattern on the side closer to the light source by exposing the same to the front surface and the back surface by using a photomask formed with the same exposure pattern. Even if it goes around, this light can be cut by the light non-transmissive part of the next exposure pattern, and it is possible to perform exposure with high accuracy. Even if the distance between the circuit board and the photomask is large, the circuit width can be reduced. It is possible to uniformly form a high-density fine pattern.

[Brief description of drawings]

1A and 1B show an embodiment of an exposure process in the present invention, in which FIG. 1A is a cross-sectional view of a circuit board covered with a photomask, FIG. 1B is a plan view of the photomask, and FIG. It is a top view which shows the formed circuit.

2A and 2B show another embodiment of the exposure process of the present invention, in which FIG. 2A is a sectional view of a state in which a circuit board is covered with a photomask, FIG. 2B is a plan view of the photomask, and FIG.
FIG. 6 is a plan view showing a formed circuit.

FIG. 3 shows an example of a process for manufacturing a three-dimensional circuit board according to the present invention, and FIGS. 3 (a) to 3 (d) are cross-sectional views of each process of the first half thereof.

FIG. 4 shows an example of a process for manufacturing a three-dimensional circuit board according to the present invention, and FIGS. 4 (a) to 4 (d) are cross-sectional views of each process of the latter half thereof.

FIG. 5 is a perspective view of a completed three-dimensional circuit board.

FIG. 6 shows another example of the manufacturing process of the three-dimensional circuit board of the present invention, and (a) to (d) are cross-sectional views of each process of the first half part thereof.

FIG. 7 shows another example of the manufacturing process of the three-dimensional circuit board of the present invention, and (a) to (c) are cross-sectional views of each process of the latter half thereof.

FIG. 8 is an exploded perspective view showing an example of alignment of the photomask according to the present invention.

FIG. 9 is a sectional view of the above-mentioned embodiment.

FIG. 10 shows the first exposure operation of the exposure step in the present invention, (a) is a sectional view, (b) is a plan view, and (c) is a plan view after exposure.

FIG. 11 is a diagram showing a second exposure operation of the exposure step in the same as above, (a) is a sectional view, (b) is a plan view,
(C) is a plan view after exposure.

12A and 12B show a three-dimensional circuit board on which a circuit is formed by the above exposure, FIG. 12A being a front view and FIG. 12B being a plan view.

FIG. 13 shows an embodiment of alignment of a photomask according to the present invention, in which (a) is an exploded perspective view,
(B) is a perspective view.

FIG. 14 shows an embodiment of the above (a),
(B), (b) is sectional drawing, respectively.

15A and 15B show another embodiment of the above, wherein FIG. 15A is a plan view of a photomask, and FIG. 15B is an enlarged cross-sectional view of a part of the circuit board and the photomask.

16A and 16B show another embodiment of the alignment of the photomask according to the present invention, in which FIG. 16A is a sectional view and FIG.
Is a plan view.

FIG. 17 is a view showing a supporting rod used in the above-mentioned embodiment, FIG. 17 (a) is a front view showing a state where it is attached to a photomask,
(B) is a perspective view.

18A and 18B show still another embodiment of alignment of a photomask according to the present invention, wherein FIG. 18A is a perspective view of a circuit board, FIG. 18B is a perspective view of a photomask, and FIG. It is a perspective view of the state which set the photomask to.

FIG. 19 shows still another embodiment of the above,
(A) is a sectional view, (b) is a plan view of a photomask,
(C) is an enlarged sectional view of a part of the photomask.

FIG. 20 shows still another embodiment of the alignment of the photomask according to the present invention, which is (a) to (e).
Is a sectional view.

FIG. 21 is a sectional view showing an example in which exposure is performed using the collimator according to the present invention.

FIG. 22 is a view showing an embodiment in which exposure is performed using a plurality of photomasks according to the present invention,
(A) is sectional drawing, (b) is sectional drawing explaining an effect | action.

FIG. 23 is a view showing the manufacture of the above photomask, and FIGS. 23A to 23E are cross-sectional views of each step.

FIG. 24 is a cross-sectional view showing an example using the above photomask.

FIG. 25 shows an embodiment in which a photomask formed by providing light non-transmissive portions on the front and back sides of the present invention is used for exposure, (a) is a cross-sectional view, and (b) shows the operation. It is sectional drawing explaining.

FIG. 26 shows the manufacture of the above photomask, and FIGS. 26A to 26D are cross-sectional views of each step.

FIG. 27 is a cross-sectional view showing an example in which exposure is performed using laser light according to the present invention.

FIG. 28 is a cross-sectional view showing an embodiment in which exposure is performed using pinholes according to the present invention.

FIG. 29 is a sectional view showing an example in which exposure is performed using sunlight according to the present invention.

FIG. 30 is a schematic view showing an example of a conventional exposure process.

FIG. 31 shows another example of a conventional exposure process, in which (a) is a cross-sectional view of a circuit board covered with a photomask, (b) is a plan view of the photomask, and (c) is formed. It is a top view which shows the circuit.

32A and 32B show another example of a conventional exposure process, in which FIG. 32A is a cross-sectional view of a state in which a circuit board is covered with a photomask, FIG. 32B is a plan view of the photomask, and FIG.
FIG. 6 is a plan view showing a formed circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board 3 Photoresist 4 Photomask 4a Light transmitting part 4b Light non-transmitting part 4'Exposure mask 4 "Light shielding mask 6 Circuit 10 Positioning part 11 Circuit board fixing jig 12 Support bar 51 Collimator 52 Optical lens 53 Pinhole 54 Optical lens 55 Light shield 56 Laser light 57 Sunlight

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 9, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

When the photomask 4 is divided into a plurality of stages and used, the photomask 4A may be partially overlapped with only the deep recess 9b. That is, as shown in FIG. 8, a photomask 4A is formed according to the planar shape of the deep recess 9b of the circuit board 1, and the photomask 4 has a light transmitting portion 4c (which transmits light according to the shape of the photomask 4A). The portion between the broken lines in FIG. 8) is formed. Of course, these photomasks 4 and 4A are formed with a light transmitting portion 4a and a light non-transmitting portion 4b for forming a circuit in a pattern shape. Then, as shown in FIG. 9, the photomask 4A is superposed on the deep recess 9b of the circuit board 1 and the photomask 4 is superposed on the step 1a on the circuit board 1. At this time, the light transmitting portion 4c of the photomask 4 is changed to the photomask 4A.
The photomask 4 and the photomask 4A are aligned and arranged so as to face each other in the irradiation direction of the parallel light. The photomask 4A has an outer shape formed in accordance with the planar shape of the recess 9b. can position-decided Mesuru by placing a photomask 4A in accordance with the shape of 9b, the photomask 4 in the embodiment of FIG. 9 are so as to align with the circuit board fixing jig 11.
That is, the circuit board fixing jig 11 is formed by forming a recess 20 on the upper surface that matches the planar shape of the circuit board 1. The circuit board fixing jig 11 is provided with screw holes 21 on the upper surface of the end portion of the circuit board fixing jig 11. Positioning holes 22 are provided at the four corners of the mask 4,
Then, the circuit board 1 is set in the circuit board fixing jig 11 by fitting the circuit board 1 into the recess 20, and the fixing screw 23 is inserted into the positioning hole 22 and screwed into the screw hole 21 to form a photomask. 4 is set in a state where it is positioned on the circuit board fixing jig 11, and the circuit board 1 and the photomask 4 are respectively positioned with respect to the circuit board fixing jig 11 in this way. The circuit board 1 and the photomask 4 can be positioned with each other. In addition to positioning the photomask 4 by using a jig such as the fixing screw 23 as shown in FIG. 9, it will be described later with reference to FIGS. 13, 14, 15, 16, 18, 18, 19, and 20. It can also be done by the method. Then, by positioning the photomask 4 and the photomask 4A in this manner, the photomask 4 and the photomask 4A can be aligned with each other. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 21, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Fig. 14

[Correction method] Change

[Correction content]

FIG. 14 shows an embodiment of the above (a),
(B), ( c ) is sectional drawing, respectively.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshitaka Tezuka 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Takako Otani, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works, Ltd.

Claims (14)

[Claims] 1. A circuit board including a step of coating a photoresist on the surface of a three-dimensional resin-molded circuit board, superimposing a flat photomask on the surface, exposing with parallel light, and then developing. In manufacturing, it is characterized in that exposure is performed using a photomask formed with a light transmitting portion whose size is adjusted according to the spread of parallel light with the distance between the photomask and the circuit forming surface of the circuit board. Manufacturing method of three-dimensional circuit board. 2. A circuit board including a step of coating a photoresist on the surface of a three-dimensional resin-molded circuit board, overlaying a flat photomask on the surface, exposing with parallel light, and then developing. A method of manufacturing a three-dimensional circuit board, characterized in that, in manufacturing, the photomask is divided into a plurality of stages according to the distance between the photomask and the circuit forming surface of the circuit board, and the photomasks are overlapped and exposed. 3. The photomask according to claim 2, wherein the photomask is formed with a light transmitting portion whose size is adjusted according to the spread of parallel light with the distance between the photomask and the circuit forming surface of the circuit board. A method for manufacturing a three-dimensional circuit board characterized by the above. 4. The three-dimensional resin-molded circuit board according to any one of claims 1 to 3, wherein a concave portion or a convex portion is integrally molded at the time of resin molding and an alignment portion is provided. A method for manufacturing a three-dimensional circuit board, comprising: stacking a photomask on a circuit board in a state of being aligned by an alignment unit. 5. A circuit board is positioned and set on a circuit board fixing jig, and a photomask is aligned with the circuit board by connecting a supporting rod detachably attached to the photomask to the circuit board fixing jig. The method for manufacturing a three-dimensional circuit board according to claim 1, wherein a photomask is superposed on the circuit board in this state. 6. Among a plurality of stages of flat photomasks,
Use an exposure mask with a light-transmitting portion patterned on one stage of the photomask, and perform exposure on a photomask of the other stage using a light-shielding mask that does not transmit light, and replace the exposure mask with the light-shielding mask in sequence. The method for manufacturing a three-dimensional circuit board according to claim 2, wherein the exposure is performed a plurality of times. 7. Among a plurality of flat photomasks,
7. The method for manufacturing a three-dimensional circuit board according to claim 2, wherein the photomasks are arranged such that the ends of adjacent photomasks overlap each other in the irradiation direction of the parallel light. 8. The photomasks are aligned in the irradiation direction of the parallel light by arranging the photomasks so that the end portions of the adjacent photomasks overlap each other, and the photomasks are aligned with each other in the overlapping portion. A method for manufacturing a three-dimensional circuit board according to. 9. The method for manufacturing a three-dimensional circuit board according to claim 1, wherein the exposure is carried out by parallel light whose parallelism is increased by a collimator. 10. A plurality of plate-shaped photomasks on which the same exposure pattern is formed are used, and a plurality of photomasks are arranged at a predetermined interval so that the exposure patterns are aligned in the parallel light irradiation direction. The method for manufacturing a three-dimensional circuit board according to any one of claims 1 to 9, further comprising: 11. The method for manufacturing a three-dimensional circuit board according to claim 1, wherein the exposure is performed using a photomask formed by providing the same exposure pattern on the front surface and the back surface, respectively. 12. The method for manufacturing a three-dimensional circuit board according to claim 1, wherein the laser light is converted into parallel light obtained by expanding a light flux using an optical lens, and the parallel light is used for exposure. . 13. The method for manufacturing a three-dimensional circuit board according to claim 1, wherein the light passed through the pinhole is converted into parallel light by an optical lens, and the parallel light is used for exposure. 14. The method according to claim 1, wherein the sunlight is introduced as parallel light while the secondary light is blocked by the blocking plate, and the parallel light of the sunlight is used for exposure. Manufacturing method of three-dimensional circuit board.