JPH11261234A - Manufacture of multi-layer conductor circuit comprising through hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing multi-layer circuit board wherein working precision at forming a through hole is high, reliability in electrical connection is improved, and manufacturing process is simplified. SOLUTION: At least one layer constituting a conductor circuit substrate of multi-layers comprising a through hole, a resin pattern is provided in a region surrounded by a conductor, and the resin pattern is removed under high energy ray irradiation with a conductor pattern allocated outside the resin pattern as a mask.

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 multilayer conductor circuit having through holes in a conductor circuit board which is becoming smaller, faster, higher in density and lower in power consumption. For example, it is extremely useful as a method for manufacturing a conductor circuit such as a planar coil for a magnetic head of a magnetic recording apparatus, in addition to a precision wiring board such as a planar coil for an electric motor or an actuator, and an interposer (different pitch connecting parts).

[0002]

2. Description of the Related Art In recent years, in order to reduce the size of a multilayer conductor circuit such as a printed circuit board, it has been desired to reduce the size of through holes and through hole lands for making electrical connection between layers. I have. In general, as a method of forming a conductive circuit, a desired circuit is formed by etching or the like using a cured resin image (hereinafter, referred to as a resin image in the present invention) of a photosensitive resin composition formed on a conductive substrate as a protective film. A subtractive method (also referred to as an etching method) for forming a resin image, an additive method for forming a conductive circuit by forming a resin image on an insulating substrate and performing electroless copper plating, and the like. Semi-additive method, which is an intermediate method of the above. As a method of forming a multilayer substrate by such a method, a build-up method is performed, and as a method of electrically connecting the multilayer conductor patterns, a method via a through hole is generally used. A method of drilling a through hole is generally a method using a drill, and a method of drilling by laser beam irradiation is also known.

[0003]

However, in a conductor circuit formed by a build-up method, a conductive pattern forming step by etching or plating after forming a photosensitive resin pattern, a photosensitive resin pattern peeling step, and Since the process of forming an insulating layer is alternately repeated, the number of processing steps is large and complicated, so that much time is required for device fabrication. In particular, when drilling a through hole using a drill, if the land positions of the upper and lower layers of the multilayer board are shifted, the hole of one of the through hole lands of the upper and lower layers will not be circular but will be chipped. The area of the part was reduced, and there was a problem in the electrical connection reliability thereafter. When a hole smaller than 300 μm is drilled, even if a carbide drill is used, there is a problem of breakage, which is not suitable for mass production. Further, since a hole is formed through a hole by drilling, it is difficult to form a hole without penetrating only the lowermost layer as in a blind via hole, and it has not been easy to perform the hole.

In the method of piercing by irradiating a laser beam, when a resin pattern does not exist inside the through-hole land, it is necessary to melt and remove the metal, and a laser device of very large energy is essential. . Therefore, when processing is performed with large energy, there is damage to the resin inside the substrate or around the through-hole land, and it has been difficult to perform processing as designed.

Further, in a method in which a build-up method and a method of forming a hole with a laser beam are combined, a resin layer at a position where a through hole is to be formed is first formed with a laser.
After that, a method of forming a photoresist pattern using a photolithography and a step of forming a conductor pattern of a land portion by electroless plating are generally used. With this method, it is necessary to finely adjust the setting conditions such as the size of the laser beam and the energy density of the laser in order to remove the resin pattern with high dimensional accuracy. Is difficult. Also known is a method of processing by attaching a metal mask with a hole at the position where the resin is removed,
In this method, when the diameter of the through hole is reduced, there is a problem that misalignment is likely to occur in alignment between the substrate and the mask, and it is difficult to secure processing accuracy.

SUMMARY OF THE INVENTION The present invention provides a method of manufacturing a multilayer conductor circuit which has high processing accuracy when forming a through hole, improves electrical connection reliability, and simplifies a manufacturing process.

[0007]

As a result of intensive studies, the present inventors have found that, in a multilayer conductor circuit, a resin pattern for forming a conductor line pattern is formed inside a through-hole land at the same time as forming a resin pattern for forming a conductor line pattern. The resin pattern is formed using photolithography, then a line pattern and a land pattern made of a conductor are produced by plating, and then several layers are laminated with an adhesive resin. It has been found that a small-diameter through hole can be formed by removing by a processing method of irradiating a line.

That is, the first invention provides a resin circuit pattern in a region surrounded by a conductor on at least one layer constituting a multilayered circuit board having through holes.
A method for manufacturing a multilayer conductor circuit, comprising a step of removing the resin pattern by irradiating a high energy beam using a conductor pattern arranged outside the resin pattern as a mask.

According to a second aspect of the present invention, at least one layer constituting a multilayer magneto-optical recording coil having through holes has a maximum width of 10 to 2 within a region surrounded by a conductor.
A method for manufacturing a magneto-optical recording coil, comprising the steps of: providing a 50 μm resin pattern, and removing the resin pattern by irradiating a high energy ray using a conductor pattern disposed outside the resin pattern as a mask.

With such a configuration, the device manufacturing process can be simplified and the manufacturing time can be shortened. In addition, through-hole drilling can be easily performed with good dimensions and positioning accuracy, and a resin pattern can be formed in the through-hole land in an arbitrary shape. It is also possible to improve dynamic connection reliability.

[0011] The high energy ray referred to in the present invention is a light ray or a particle beam having a high energy density such as a laser beam, an electron beam, an ion beam, and plasma. In these high-energy rays, use of a laser beam is particularly preferable because of simplicity of processing that can be used in a normal pressure environment without requiring a vacuum vessel. The type of the laser beam is not particularly limited, but a laser beam having a large energy such as a carbon dioxide laser, an excimer laser, a neodymium / YAG laser, and an HF chemical laser can be used. The type of ion beam is not particularly limited, but includes argon ion, xenon ion,
Oxygen ions, gallium ions, cesium ions, or the like can be used. The shape of the resin pattern 1 to be removed is not particularly limited, and may be circular, elliptical,
Any pattern such as a polygon such as a quadrangle or a triangle, or a pattern in which a plurality of these patterns are arranged may be used. By forming a resin pattern with a complicated shape inside the through-hole land, it is possible to increase the surface area of the inner wall of the through-hole for making electrical connection between the multilayers, and to improve the electrical connection reliability. it can.

The photosensitive resin composition used in the present invention is not particularly limited, but may be an ordinary liquid photosensitive resin, a dry film resist, a negative photoresist, a positive photoresist, or the like. In particular, for the purpose of forming a thick-film conductor pattern in which the thickness of the conductor exceeds 20 μm and the pitch between the wirings is narrow, International Publication No. WO97 / 50280.
The use of the liquid photosensitive resin composition disclosed in (1) is preferred.
Conventional photoresists such as cyclized rubber-based and azide-based photoresists can be used as the negative photoresist, and quinonediazide-based photoresists can be used as the positive photoresist.

The conductive substrate is not particularly limited, but a substrate made of aluminum, copper, or the like is preferably used. If necessary, the conductive substrate may be subjected to a physical or chemical surface treatment, for example, in order to improve the adhesion between the conductive substrate and the photosensitive resin composition or the plating film. The method of electrical connection of the through-hole of the present invention is not particularly limited, but a method of performing electroplating by applying a conductive compound to the inner wall in the through-hole, a method of electroless plating on the inner wall of the through-hole, and a method of thickness. A conductive film is formed by plating such as a method of performing electroless plating after performing thin electroless plating (see FIG. 1 (c) described later), or a conductive paste containing conductive particles is filled to form a conductive filler. An ordinary method such as forming (see FIG. 1D described later) can be used.

In the method for establishing electrical connection using the conductive paste, the conductive paste to be used is not particularly limited, but may include a solder paste, a copper paste, a silver paste, a copper paste coated with silver on the surface or a surface containing copper particles. Conductive paste containing silver / copper particles with high silver concentration,
Conductive paste containing copper particles solder-plated on the surface, resin paste coated with a metal film on the surface, or conductive paste containing inorganic particles such as ceramics can be used. By heating after filling, the paste can be hardened and conduction can be obtained. Also, as a method of increasing the filling rate of the conductive paste in the through hole and improving the connection reliability, the conductive paste is preheated, and then filled in the through hole. For example, a method of compressing the conductive paste in the through hole is effective.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a multilayer conductor circuit according to the present invention will be described below with reference to the drawings. 1 to 3 are schematic sectional views showing the steps, and show through-hole portions for simplification. First, a photosensitive resin composition is applied on a conductive substrate, and is exposed to energy rays such as a mercury lamp through a photomask or the like, and then the unexposed portion of the photosensitive resin composition is dissolved or dispersed in a developer. After removing and forming a desired resin pattern on the conductive substrate, a conductor is formed by electrolytic plating. Next, after the electroplating, the insulating material 3 is bonded to the surface of the conductive pattern opposite to the conductive substrate, or a plurality of conductive patterns are laminated via the insulating material, and then the conductive substrate is removed. As a method for removing the conductive substrate, for example, a method of etching with an aqueous solution of an acid, an alkali, a salt, or the like, a method of polishing and shaving, a method of mechanical peeling, or a combination thereof can be used.

If necessary, the resin image portion may be removed before transferring the conductive pattern to the insulating substrate or after transferring and removing the conductive substrate. The insulating material 3 used in the transfer is not particularly limited, but a normal adhesive resin such as an epoxy adhesive resin, an acrylic adhesive resin, a polyimide adhesive resin, a maleimide adhesive resin, a styrene adhesive resin, and a polyester adhesive resin is used. Can be. The formed insulating material layer functions as an electrical insulating layer between the layers forming the multilayer circuit board. When the resin image portion is removed before the transfer, the insulating material also functions as an electrical insulating resin between the conductor patterns in the same layer. In order to reinforce the circuit board, a film such as a polyimide film or an aramid film, a glass cloth, or the like may be included in the layer of the insulating material 3.

FIG. 1A shows a conductor circuit in which the conductive substrate is removed and the first-layer circuit 4 and the second-layer circuit 5 are bonded via an insulating material 3. A resin pattern is formed in advance inside a through-hole land for connecting a conductor portion between the multilayers, and a through-hole land including a resin pattern 1 and a conductor pattern 2 is formed by performing electrolytic plating. The size of the resin pattern 1 inside the through hole land is preferably 10 to 250 μm. If the size of the resin pattern is smaller than 10 μm, it is difficult to ensure connection reliability by through holes between the multilayers.
When the size exceeds 0 μm, there is a problem that the size of the device becomes large.

Then, the resin pattern 1 is removed by irradiating the high-energy ray 8 to the through hole land portion (FIG. 1).
(B)), a conductive film 6 is formed in the through hole,
Electrical connection is made (FIG. 1 (c)). Alternatively, a conductive paste containing conductive particles is filled in the through holes to form a conductive filler 7 (FIG. 1D). In the present invention, since the through-hole land portion in at least one layer is composed of the conductor pattern 2 and the inner resin pattern 1, when the resin pattern 1 is removed by irradiating high energy rays such as laser light, Conductor pattern 2 functions as a light-shielding mask, and the resin portion can be removed with high accuracy. If the outer conductor pattern 2 does not exist, it is necessary to finely adjust the setting conditions such as the beam size and the energy density in order to remove the resin with high dimensional accuracy. Difficult to open.

As a method of forming the conductor and the resin pattern of the first layer circuit 10 on the insulating substrate, a method shown in FIG. 2A can be adopted. That is, the conductor on the insulating substrate,
As a method for forming the resin pattern, an additive method in which a photosensitive resin on the insulating substrate 9 is patterned using photolithography and then a conductive pattern is formed between the resin patterns by plating, or a conductive foil on the insulating substrate is etched. A subtractive method of patterning can be used. Thereafter, as shown in FIGS. 2B and 2D, the insulating material 3 is laminated, and a second-layer circuit 11 is formed thereon. As a method of forming the circuit 11, an additive method combining photolithography and a plating method or FIG.
As shown in (c) and (d), a method can be used in which the conductive foil is patterned by etching and then embedded in a resin layer.

A method of manufacturing a conductor circuit having a blind via hole as shown in the schematic sectional views of FIGS. 3A to 3D will be described below. A first layer circuit 4 having a through hole land made of a resin pattern 1 and a conductor pattern 2 is formed on one surface of an insulating material 3, and a second layer circuit having a through hole land 12 made of only a conductor is formed on the other surface. Form a circuit. Next, the resin pattern 1 is irradiated with high-energy rays 8 using the conductor pattern 2 as a mask and removed. At this time, the through-hole land 12 made of only a conductor is used.
Is not removed by the high-energy ray 8 and remains as it is. Next, a conductive film 6 is formed in the through hole, or a conductive paste is filled to form a conductive filler 7.

In the present invention, when the resin pattern 1 exists inside the through-hole lands of all the layers, when the respective layers are transferred and then the resin pattern is removed by high-energy ray irradiation, the through-holes as shown in FIG. As shown in FIG. 3 (a), when all the through-hole lands of one layer are formed of a conductor pattern, a blind via hole with one side closed can be formed.

In the step of laminating two or more conductive circuit boards with an adhesive resin, even if the positions of the through holes of the respective layers are shifted within the range of the land size, holes are formed by irradiating high energy rays. It is not necessary to make a hole in the portion, and it is possible to avoid a reduction in the size of the land. Further, in the present invention, one or more layers are further adhered to the outside through an insulating material after the electrical conduction of the through hole formed by irradiating a high energy beam such as a laser beam, and then the through hole is formed in a similar manner. To form a multilayer substrate.

Hereinafter, the present invention will be described in detail with reference to examples. The present invention is not limited by the embodiments.

[0024]

Example 1 An alkali-developing liquid photosensitive resin was cured on a photomask having a coil-shaped pattern with a coil size of 2 mm in diameter and a pitch of 30 μm through a PET film of 10 μm in thickness. It was applied so as to have a thickness of 60 μm, and an aluminum substrate was laminated thereon. Exposure using parallel light from a mercury short arc lamp, development with a 1% aqueous sodium borate solution, 85 ° C
Was rinsed with hot water for 10 minutes to perform post-curing.

Next, strike plating is performed at a current density of 3 A / dm 2 for 6 minutes using a copper pyrophosphate plating solution manufactured by Uemura Kogyo Co., Ltd.
A conductive pattern of 0 μm was formed. The through-hole land portion was composed of a conductor pattern having an outer diameter of 160 μm and a resin pattern having an outer diameter of 100 μm at the center thereof, and was simultaneously formed in a coil-shaped pattern forming step.

The two-layer circuit composed of the conductor and the resin pattern prepared as described above was laminated via a 25 μm-thick polyimide film using a WA-modified acrylic adhesive manufactured by DuPont, and the aluminum substrate was removed by etching with hydrochloric acid. . A 100-μm-diameter resin pattern at the center of the through-hole land located at the center of the coil was removed by irradiating a carbon dioxide laser beam to form a through-hole. The removal of the resin pattern by the carbon dioxide gas laser was easily performed without strict adjustment of the diameter and output of the laser beam, with the conductor pattern disposed outside serving as a light-shielding mask. Laser drilling is made by Mitsubishi Electric ML
This was performed using a 505GT carbon dioxide laser processing machine. The output of the laser beam was 300 W, the pulse width was 50 μs, and the beam diameter was 60 μm. A through hole having an outer diameter of 100 μm and an aspect ratio of 2 was produced. Plus 90
A conductive paste containing silver / copper particles having a high silver concentration on the surface pre-heated at 60 ° C. for 60 minutes was filled and electrically connected after the heat treatment to produce a small planar coil. The resistance value of the through hole was less than 0.2Ω, and no change in the resistance value was observed in the heating test at 230 ° C. for 10 minutes.

[0027]

Example 2 A conductor / resin pattern was prepared in the same manner as in Example 1 except for the method of electrically connecting through holes. Electrical connection method of through hole portion The connection was performed as follows. The inner wall of the through hole was treated with a direct plating solution manufactured by Okuno Pharmaceutical Co., Ltd., and then a 10 μm thick copper film was formed on the inner wall of the through hole by copper sulfate plating.
The resistance value of the through hole is less than 0.2Ω, 230 ° C
No change in resistance was observed in the 10 minute heating test.

[0028]

Example 3 A conductor / resin pattern was prepared in the same manner as in Example 1 except for the method of electrically connecting through holes. Electrical connection method of through hole portion The connection was performed as follows. The inner wall of the through hole was treated in the order of a stannous chloride hydrochloric acid solution and a palladium chloride hydrochloric acid solution. Then, it was immersed in an electroless plating solution manufactured by Uemura Kogyo Co., Ltd. at 55 ° C. for 90 minutes,
Further, a copper film having a thickness of 20 μm was formed on the inner wall in the through hole by plating with copper sulfate. The resistance value of the through hole was less than 0.2Ω, and no change in the resistance value was observed in the heating test at 230 ° C. for 10 minutes.

[0029]

Embodiment 4 An example of a conductor circuit having a blind via hole shown in FIG. 3 will be described. Size of coil part is diameter 2
The thickness after curing of the alkali-developable liquid photosensitive resin through a 10 μm thick PET film on a photomask having a coiled pattern with a pitch of 30 μm and a pitch of 30 μm is 60 mm.
μm, and an aluminum substrate was laminated thereon. After exposure using parallel light from a mercury short arc lamp, development with a 1% aqueous sodium borate solution, rinsing with hot water at 85 ° C. for 10 minutes and post-curing to form a resin pattern 2.

Next, strike plating was performed at a current density of 3 A / dm 2 for 6 minutes using a copper pyrophosphate plating solution manufactured by Uemura Kogyo Co., Ltd.
A conductive pattern of 0 μm was formed. The through-hole land portion was composed of a conductor pattern 2 having an outer diameter of 160 μm and a resin pattern 1 having an outer diameter of 100 μm at the center thereof, and was simultaneously formed in a coil-shaped pattern forming step. In the same manner, a second layer circuit 13 having a conductor pattern 12 having a through hole land portion having an outer shape of 160 μm was formed. The first-layer circuit 4 having the conductor / resin pattern in the through-hole land portion and the second-layer circuit 13 having the through-hole land portion made of only the conductor manufactured as described above were combined with a WA-modified acrylic adhesive (insulated by DuPont). Using the material 3), a polyimide film having a thickness of 25 μm was inserted therebetween and laminated, and the aluminum substrate was removed by etching with hydrochloric acid. A blind hole was formed by removing the resin pattern having a diameter of 100 μm at the center of the through hole land located at the center of the coil by irradiating a carbon dioxide gas laser beam. The removal of the resin pattern by the carbon dioxide gas laser was easily performed without strict adjustment of the diameter and output of the laser beam, with the conductor pattern disposed outside serving as a light-shielding mask. A blind hole having an outer diameter of 100 μm was produced.

Further, a conductive paste containing silver / copper particles having a high silver concentration on the surface preheated at 90 ° C. for 60 minutes is filled, and after the heat treatment, is electrically connected to form a small planar coil for magneto-optical recording. Produced. The resistance value of the through hole is 0.
It was less than 2Ω, and no change in resistance was observed in a heating test at 230 ° C. for 10 minutes.

[0032]

COMPARATIVE EXAMPLE 1 Before drilling by laser beam irradiation in the same manner as in Example 1, except that the through-hole land portion shown in FIG. 3 was formed by laminating two layers consisting of only the conductor pattern 12 with an insulating material interposed therebetween. Was produced. An attempt was made to drill through holes using the same conditions and the same laser processing apparatus as in Example 1, but no holes could be drilled.

[0033]

COMPARATIVE EXAMPLE 2 As shown in FIG. 4A, a circuit pattern 15 in which no conductor pattern is arranged on a through-hole land is formed, two layers are laminated in the same manner as in Example 1, and a laser is used under the same conditions. As a result of an attempt to drill a hole, the minimum dimension of the formed oval hole was 130 μm for a circular hole having a design size of 100 μmφ.

[0034]

COMPARATIVE EXAMPLE 3 As shown in FIG. 4 (a), a first layer circuit 15 in which no conductor pattern is arranged on the through hole land and a second layer circuit 13 in which the through hole land portion is composed only of the conductor pattern are formed. The two layers are laminated in the same manner as in the first embodiment, a metal mask 16 having a circular hole of 100 μmφ is arranged on the upper portion, and a laser beam is irradiated under the same conditions as in the first embodiment to form a hole. Was carried out. As shown in FIG. 4B, the center of the opened hole was shifted by 20 μm from the designed position of the circuit.

[0035]

According to the present invention, by providing a resin pattern inside a through-hole land, it is possible to reduce the energy of a high-energy ray used for removing the resin pattern when forming a through-hole after the laminating step. When the resin pattern is removed, the conductor pattern disposed outside serves as a guide, so that a hole can be formed with high dimensional accuracy. Furthermore, a small-diameter through hole can be formed with high positioning accuracy because a metal mask for drilling is not required.

Furthermore, since the conductor pattern in the land portion of the through hole and the resin pattern inside can be formed simultaneously in one lithographic process, the process of manufacturing a multilayer conductor circuit board having small diameter through holes can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a manufacturing process according to the present invention.

FIG. 2 is an explanatory view of a manufacturing process according to the present invention.

FIG. 3 is an explanatory diagram of a manufacturing process of a blind via hole according to the present invention.

FIG. 4 is an explanatory diagram of a comparative example.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 resin pattern inside through hole land 2 conductor pattern of through hole land 3 insulating material 4 first layer circuit 5 second layer circuit 6 conductive film on inner wall of through hole 7 conductive filler in through hole 8 high energy Line 9 Insulating substrate 10 First layer circuit 11 Second layer circuit 12 Through hole land consisting only of conductor 13 Circuit having through hole land portion consisting of only resin pattern 14 Circuit having through hole land consisting of only conductor 15 Resin Circuit of the first layer having through-hole lands consisting only of patterns 16 Metal mask 17 Deviation of center position of through-hole from design value

Claims (2)

[Claims] At least one layer constituting a multi-layer conductive circuit board having through-holes is provided with a resin pattern in a region surrounded by a conductor, and a high level is formed by using the conductor pattern disposed outside the resin pattern as a mask. A method for manufacturing a multilayer conductor circuit, comprising a step of removing the resin pattern by irradiation with energy rays. 2. A resin pattern having a maximum width of 10 to 250 μm is provided in a region surrounded by a conductor in at least one layer constituting a multilayer magneto-optical recording coil having a through hole, and a resin pattern is provided outside the resin pattern. A method for manufacturing a coil for magneto-optical recording, comprising a step of removing a resin pattern by irradiating a high-energy ray using an arranged conductor pattern as a mask.