JP2001168485A - Wiring board and transfer medium and manufacturing method for them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductor-wiring substrate, that has improved adhesion properties to the insulation substrate of a wiring pattern and has an improved yield, even if a fine wiring pattern is formed, a transfer medium for transferring conductor wiring to the insulation substrate of the conductor wiring substrate, and a method for easily manufacturing them. SOLUTION: A substrate surface is exposed selectively to the surface of an aluminum substrate 10 for transfer media by photoresist technique, a metal layer 104, where a metal particle mass growth direction is nearly in parallel with the substrate surface is formed on the exposed substrate surface, a meta layer 105, where the metal particle mass growth direction is nearly vertical to the substrate surface is formed by the non-luster plating, the obtained transfer medium is crimped to an insulation substrate 201 with an adhesive 202 on the surface, metal layers 104 and 105 that become conductor wiring are transferred and embedded onto the surface of the insulation substrate, and the substrate 101 of the transfer medium is chemically etched for removal, thus obtaining the wiring board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board having a fine wiring pattern capable of forming an electronic circuit by mounting and electronically connecting various electronic components on the surface thereof, a method of manufacturing the same, and a wiring board. The present invention relates to a transfer medium for manufacturing and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, with the increase in the frequency and miniaturization of electronic equipment, there has been a strong demand that a circuit board on which a semiconductor chip such as an LSI can be mounted at a low cost is widely used not only in industrial applications but also in the field of consumer electronics. Have been. In such a circuit board, it is possible to easily and finely produce a finer wiring pattern with a constant circuit constant such as a wiring impedance to cope with a high frequency and to achieve a miniaturization purpose by improving a mounting density. is important.

Conventionally, in a circuit board, a method of forming a wiring pattern by attaching a copper foil to a so-called glass epoxy substrate in which a glass woven fabric is impregnated with an epoxy resin and photoetching the copper foil has been adopted. The copper foil surface is roughened in order to maintain the adhesion between the copper foil and the glass epoxy substrate.Therefore, it is necessary to thicken the copper foil, It was difficult to form a complicated wiring pattern.

In order to solve this problem, for example, a fine pattern for conductor wiring is formed on another substrate in advance by electroplating or the like, and then pressed onto an insulating base material to transfer the metal layer pattern for conductor wiring. Further, a method of mechanically peeling only the substrate after that has been proposed (Japanese Patent Laid-Open No.
-318783).

[0005]

However, what is disclosed herein is an additive which forms a fine pattern of a photosensitive resin on another substrate (substrate for a transfer medium) in advance to ensure uniformity. Conductor wiring is formed by electroplating including the photosensitive resin, and then the photosensitive resin is removed, and further roughening plating is performed on the surface of the plated conductor wiring to secure the adhesion strength, and a transfer medium is created. By pressing the insulating substrate for the wiring substrate, the conductor wiring is transferred onto the insulating substrate, and thereafter, only the substrate of the transfer medium is mechanically peeled off. In such a method, even if the side wall of the conductor wiring first formed by plating with the photosensitive resin has good linearity, the conductor is removed by removing the photosensitive resist and performing rough plating again. Rough plating is also formed on the side wall of the wiring pattern. As a result, the linearity of the side wall of the conductor wiring is lost, and the wiring width dimension microscopically varies. This causes variations in circuit constants and variations in high-frequency characteristics, and also causes a reduction in product yield due to short-circuiting of fine patterns. Here, in order to form the metal layer by plating in a fine pattern, a bright material or the like is added to the plating solution, and the growth direction of the metal particles in the formed plating layer is substantially parallel to the substrate. However, when a semiconductor chip or the like is mounted on a wiring board, it is desirable to adjust the height of the bumps of the semiconductor chip or the like according to the surface roughness of the wiring board, which is desirable. When the transfer is performed, the peel strength becomes very weak. On the other hand, according to a plating solution that does not contain the additive as described above or a plating solution that can be roughened, the direction of grain growth by plating becomes almost perpendicular to the substrate surface, and it is extremely difficult to perform plating on fine parts. Becomes In other words, a wiring having a pattern width of 40 μm or more can be formed relatively easily without particular contrivance by plating, but if the pattern is smaller than this, it is necessary to increase the thickness in order to prevent an increase in electric resistance. When the plating layer is formed with a thickness of, for example, 5 μm or more, the thickness of the pattern mask material becomes large, and it becomes difficult for the plating solution to enter a minute portion due to repelling of the plating solution due to surface tension.

Further, there is a problem that the wiring pattern is separated from the wiring substrate depending on the peel strength between the wiring pattern and the substrate.

That is, in the production of a wiring board by transfer using a transfer medium, the plated metal layer is peeled off from the substrate having the weaker adhesion strength due to the difference in mechanical adhesion strength, and the plated metal layer is separated from the substrate having the stronger adhesion strength. It is transferred to the substrate. However, it is very difficult to control the adhesion strength to the transfer medium substrate and the adhesion strength to the wiring substrate insulating substrate when the metal wiring pattern is pressed and transferred from the transfer medium to the wiring substrate. In particular, when the metal wiring pattern becomes finer, the total contact area between the metal wiring pattern and the insulating substrate for a wiring board becomes smaller, and it becomes difficult to mechanically peel the metal wiring pattern from the transfer medium. Therefore, there is a problem that the yield of productivity is reduced due to deformation or disconnection of the metal wiring pattern.

According to the present invention, in a wiring board, a metal wiring pattern has excellent adhesion to an insulating substrate, does not vary in circuit constants, maintains uniformity, has stable high-frequency characteristics, and has little variation in high-frequency characteristics. Even if a fine wiring pattern is formed, a conductor wiring board with a good product yield, a transfer medium for transferring the conductor wiring to an insulating substrate of the conductor wiring board, a large-scale facility and complicated processes are required. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a conductor wiring board having the above-described excellent performance and a method for manufacturing a transfer medium relatively easily.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides the following wiring board, a method for manufacturing the same, a transfer medium for manufacturing the wiring board, and a method for manufacturing the same.

(1) In a wiring board according to the present invention, at least a portion of a conductive wiring is buried in an insulating substrate in a thickness direction of the insulating substrate, and an upper layer portion of a metal layer forming the conductive wiring is formed. Is a substantially flat upper surface, and the lower surface of the lower layer portion is a roughened surface.

When the conductor wiring is at least partially embedded in the insulating substrate, the peel strength of the conductor wiring is increased.
The upper surface of the upper layer portion of the conductor wiring is kept substantially smooth, so that when a semiconductor chip or the like is mounted on a wiring board, the upper surface of the conductor wiring is smooth, so that the upper surface of the conductor wiring depends on the surface roughness of the wiring board. Therefore, there is no need to adjust the height of the bumps of the semiconductor chip, etc., and the lower surface of the lower layer is roughened to improve the peel strength of the conductor wiring from the substrate. A wiring board is provided.

(2) In the wiring board, the metal layer forming the conductor wiring is composed of a plurality of layers, and the growth direction of the metal particles in the upper metal layer is substantially parallel to the surface of the insulating substrate; It is preferable that the growth direction of the metal particles in the lower metal layer is substantially perpendicular to the surface of the insulating substrate.

In the buried conductor wiring, the growth direction of the metal particles in the upper metal layer is substantially parallel to the surface of the insulating substrate. In addition, since the structure is such that the growth direction of the metal particles is parallel to the current, a wiring having good electric characteristics, particularly high-frequency characteristics, can be obtained. Furthermore, by embedding fine conductor wiring in which the lower surface of the lower layer is roughened by making the growth direction of the metal granules of the lower metal layer substantially perpendicular to the surface of the insulating substrate, that is, in a columnar growth. An object of the present invention is to provide a wiring board having high peel strength and excellent electric characteristics due to the presence of the upper metal layer.

(3) In the wiring board according to any one of the above items (1) and (2), it is preferable that unevenness on the lower surface of the lower metal layer is further roughened.

The peel strength of the formed conductor wiring can be further increased by making the unevenness of the lower surface of the lower layer portion of the buried conductor wiring rougher by, for example, a technique such as metal grain boundary etching treatment.

(4) In the wiring board according to any one of the above items (1) to (3), the insulating substrate is formed of a resin film having an adhesive layer formed on a surface portion thereof, and Preferably, wiring is embedded in the adhesive layer.

By using a film as the insulating substrate to stabilize the dimensional change, an adhesive is formed on the insulating substrate, and the conductor wiring is embedded in the adhesive layer, whereby the peel strength of the conductor wiring is further improved. It is possible to obtain an improved and highly reliable wiring board.

(5) In the transfer medium of the present invention, a metal layer is formed on a transfer medium substrate having at least a surface having conductivity in a pattern symmetrical with a pattern to be a conductor wiring. The lower surface of the lower portion of the metal layer is substantially smooth, and the upper surface of the upper portion is a roughened surface. Transfer media.

A metal layer is formed on a substrate having at least a surface having conductivity in a pattern symmetrical to a pattern to be a conductor wiring, and a lower surface of a lower portion of the metal layer is substantially smooth. By forming a metal layer in which the upper surface of the upper layer portion is a roughened surface, a transfer medium suitable for easily manufacturing the wiring board having excellent effects as described in (1) above. Is provided.

(6) In the transfer medium, the metal layer formed in a pattern symmetrical to the pattern to be the conductor wiring is composed of a plurality of layers, and the growth direction of the metal particles in the lower metal layer is directed to the substrate. It is preferable that the direction of growth of the metal granules of the upper metal layer is substantially parallel to the surface and is substantially perpendicular to the surface of the substrate.

The growth direction of the metal lumps is formed on the transfer medium substrate having at least a conductive surface in a direction substantially parallel to the surface of the substrate, and the growth direction of the metal lumps is substantially perpendicular to the surface of the substrate. (2) by forming a metal conductor pattern which is symmetrical with the conductor wiring formed in (2).
It is intended to provide a transfer medium capable of easily manufacturing a wiring board having the excellent effects described in the section.

(7) In the transfer medium according to any one of the above items (5) and (6), it is preferable that unevenness on the upper surface of the upper metal layer is further roughened.

The roughness of the upper surface of the upper metal layer is further roughened by, for example, a metal grain boundary etching process, so that the peel strength of the formed conductor wiring when the wiring substrate is manufactured by transfer is improved. It is an object of the present invention to provide a transfer medium which can be further increased and can easily manufacture the wiring board having the excellent effects mentioned in the above item (3).

(8) In the transfer medium according to any one of the above items (6) and (7), a metal similar to the metal constituting the conductor wiring to be formed later is coated on the transfer medium substrate. It is preferable that a metal layer composed of the plurality of layers is formed on the metal-coated surface in a pattern symmetrical with a pattern to be a conductor wiring.

Since a metal such as flash copper, which is similar to the metal constituting the conductor wiring to be formed later, is previously formed on the substrate for the transfer medium as a pretreatment for plating, Since this can be used as a nucleus for plating a metal layer formed on the substrate in a direction substantially parallel to the surface of the substrate, the growth direction of the metal granules for conductor wiring formed thereon can be easily applied to the wiring pattern. This makes it possible to provide a transfer medium having a plane-symmetric fine pattern.

(9) In the method of manufacturing a wiring board according to the present invention, the transfer medium according to any one of the above (5) to (8) is pressure-bonded to the insulating substrate, and the transfer medium is formed on the transfer medium. Transferring the conductive wiring to the surface of the insulating substrate and transferring the conductive wiring so that at least a part of the conductive wiring is buried in the thickness direction of the conductive wiring, leaving the conductive wiring and chemically eluting or decomposing the substrate of the transfer medium. This is a method for manufacturing a wiring board, which includes a step of selectively removing the wiring board.

Using the above-described transfer medium in which conductive wiring is formed on a substrate having a conductive surface, pressing the transfer medium and the insulating substrate, and embedding the conductive wiring of the transfer medium on the surface of the insulating substrate; The step of leaving the conductor wiring and selectively removing the substrate of the transfer medium by chemical elution or decomposition, whereby the conductor wiring is completely transferred, and is fine and has high peel strength. And a wiring board having a wiring pattern with a flat surface.

(10) In the method for manufacturing a wiring board according to the above mode (9), the insulating substrate to which the transfer medium is pressed is a resin film having an adhesive layer adhered to a surface portion thereof. As the conductor wiring is embedded in the adhesive layer,
It is preferable that the transfer medium and the insulating substrate are pressure-bonded.

The dimensional change is stabilized by using the insulating substrate as a film, an adhesive is formed on the insulating substrate, and the conductor wiring is embedded in the adhesive layer, whereby the peel strength of the conductive wiring is reduced. It is possible to manufacture a wiring board which is further improved and has high reliability.

(11) Further, according to the invention of the method for manufacturing a transfer medium of the present invention, a desired resin pattern is formed on the surface of a transfer medium substrate having at least a surface having conductivity, thereby forming the resin. (5) The method according to the above (5), comprising the steps of selectively exposing a non-existent substrate surface, forming a bright plating on the exposed substrate surface, and then forming a non-glossy plating thereon. Or (6)
13. The method for producing a transfer medium according to any one of the above items.

Forming a desired resin pattern on the surface of the transfer medium substrate to selectively expose the resin-free substrate surface; and forming glossy plating on the exposed substrate surface. The upper surface of the upper metal layer is roughened by the step and then the step of forming a non-glossy plating thereon, and the lower surface of the lower metal layer is smooth,
An object of the present invention is to make it possible to manufacture a transfer medium having a fine conductor wiring pattern which is plane-symmetric with the conductor wiring pattern. Further, it is possible to manufacture a transfer medium that can easily manufacture the wiring board having the excellent effects mentioned in the above item (2).

(12) In the method of manufacturing a transfer medium according to the present invention, the transfer medium substrate having at least a surface having conductivity is made of a metal similar to a metal constituting a conductor wiring to be formed later on the substrate surface. Forming a desired resin pattern on the metal surface on which the resin is formed, thereby selectively exposing the metal surface free of the resin. Preferably, the method for producing a transfer medium according to the above (8) includes a step of forming a plating and a step of subsequently forming a non-glossy plating thereon.

A metal similar to the metal constituting the conductor wiring to be formed later, such as flash copper, is previously formed on the substrate for the transfer medium as a pre-treatment for plating. Since this can be used as a nucleus at the time of bright plating for the conductor wiring formed thereon, it is possible to easily manufacture a transfer medium having a fine pattern which is plane-symmetric with the wiring pattern. .

(13) In the method for manufacturing a transfer medium according to any one of the above items (11) and (12), it is preferable that the glossy plating and the non-glossy plating of the transfer medium are electroplating.

By forming the conductor wiring of the transfer medium by electroplating, the formation of the conductor wiring can be facilitated. By forming the non-glossy plating after the formation of the bright plating, the plating growth can be easily started on the fine wiring portion by the bright plating first. Then, the side wall in contact with the photosensitive resin by the non-glossy plating is smooth and has good linearity, and it is possible to manufacture a transfer medium for conductor wiring transfer, in which only the surface is rough.

(14) In the method for producing a transfer medium according to any one of the above (11) to (13), the bright plating is plating using a plating solution containing a brightener, and the non-glossy plating is It is preferable that the plating is performed using a plating solution containing no brightener.

Since the bright plating to be plated first uses a plating solution containing a brightener, the plating solution easily penetrates into the selectively exposed fine pattern portion of the substrate formed by the resin pattern. Since the lower metal layer can be formed on the lower metal layer of the fine pattern, and the lower metal layer is formed on the non-glossy plating formed thereon, the upper metal layer of the fine pattern can be easily formed. Therefore, the transfer medium described in the above (5) or (6) can be easily manufactured.

(15) In the method for manufacturing a transfer medium according to any one of the above (11) to (14), after forming the non-glossy plating, the unevenness of the exposed surface of the formed non-glossy plating layer is further reduced. It is preferable to perform a roughening treatment so that the resin becomes coarse, and then remove the resin formed in a pattern.

After the formation of the non-glossy plating, a roughening treatment is performed so that the unevenness of the exposed surface of the formed non-glossy plating layer is further roughened, and then the resin formed in the pattern is removed. During the surface treatment, the side walls of the upper and lower conductive metal layers formed by plating are protected by resin, and therefore, the unevenness only on the exposed surface of the non-glossy plating layer can be further roughened. It is possible to manufacture a transfer medium suitable for manufacturing a wiring board having high peel strength of a conductor wiring to an insulating substrate without being roughened.

(16) In the method for manufacturing a transfer medium according to the above (15), the roughening treatment is preferably metal grain boundary etching.

By making the roughening treatment a metal grain boundary etching treatment, the unevenness of only the exposed surface of the non-glossy plating can be further roughened without much affecting the lower conductive metal layer, and the insulation of the conductor wiring can be reduced. It is possible to manufacture a transfer medium suitable for manufacturing a wiring board having a high peel strength to a substrate.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Taking a representative embodiment of the present invention as an example, the manufacture of a wiring board of the present invention will be described.
First, by forming a desired resin pattern on the surface of the transfer medium substrate having at least a surface having conductivity,
The substrate surface free of the resin is selectively exposed. The pattern of the selectively exposed substrate surface is a pattern which is plane-symmetric with the intended final conductor wiring pattern. The conductor wiring of the transfer medium is formed on the exposed surface of the substrate by plating, preferably by electroplating, in a pattern symmetrical to the intended final conductor wiring pattern. In this plating, after forming a metal layer by bright plating that can uniformly form a conductive metal film even on a fine part, the metal layer by matte plating with a relatively rough surface with this plating layer as a nucleus To form By doing so, a lower metal layer is formed on the substrate surface of the transfer medium, in which the growth direction of the metal granules is formed in a direction substantially parallel to the substrate surface of the transfer medium, and the growth direction of the metal granules is transferred thereon. A transfer medium is manufactured in which the upper metal layer is formed in a direction substantially perpendicular to the substrate surface of the medium, and preferably, the upper surface thereof is further roughened by a technique such as metal grain boundary etching.

The transfer medium thus obtained is pressed against an insulating substrate for forming a wiring substrate, and the conductor wiring formed on the transfer medium is transferred to the surface of the insulating substrate, and at least a part thereof is embedded in the thickness direction. Transfer as follows. Then, the transferred conductor wiring can be manufactured by leaving the substrate of the transfer medium alone by chemical elution or decomposition and selectively removing it. Therefore, in the obtained wiring board, the surface of the metal layer in contact with the substrate surface is roughened, and the peel strength with the substrate is improved, and the transferred and formed conductor wiring is embedded in the insulating substrate. In addition, the peel strength with the substrate is further improved.

When the conductor wiring is buried in the insulating substrate, the side wall of the conductor wiring is completely buried so that the side wall of the conductor wiring cannot be seen from the side of the insulating substrate (100% of the side wall height). Of the side wall height is buried in the thickness direction (less than 100%), and part of the height of the side wall is buried in the substrate surface. It includes the case where it is buried. In the present invention, this is described as follows.
And at least a part thereof is buried in the thickness direction. " Hereafter, in order to simplify the expression,
These may be simply expressed as "at least part of the conductor wiring is buried in the insulating substrate".
Of course, in the embedded conductor wiring, the surface of the conductor wiring is exposed on the surface of the conductor wiring opposite to the insulating substrate surface.

In the present invention, the phrase “the direction of growth of metal lumps is substantially parallel to the surface of the substrate” is not limited to the direction in which the direction of growth of metal lumps is parallel to the surface of the substrate. The growth direction may be slightly inclined from the substrate surface, and the inclination angle is not particularly limited, but includes those in which the growth direction of the metal particle mass is within ± 30 degrees from the substrate surface. . Further, in the present invention, "the growth direction of the metal granules is substantially perpendicular to the substrate surface"
The growth direction of the metal granules is not limited to only the direction perpendicular to the substrate surface, and may be slightly inclined from the direction perpendicular to the substrate surface. Although not limited, those having an angle within ± 30 degrees from the direction perpendicular to the substrate surface are also included.

Hereinafter, embodiments of the present invention will be described with reference to the drawings with reference to specific examples of a wiring board.

(Embodiment 1) As shown in FIG. 1A, a conductive metal thin plate is used as a substrate 101 for a transfer medium.
A metal layer 102 serving as a nucleus for forming a pattern made of a conductive wiring material is formed on the surface of the thin metal plate.
(A)]. For example, aluminum is used as the material metal of the substrate 101, and its thickness is about 1 mm or less, which can be removed by chemical etching in a subsequent step (a step of selectively eluting or decomposing to remove). However, if it is too thin, it may be difficult to handle, so that the thickness is preferably 5 μm or more, and more preferably 20 μm or more.
１００100 μm, and here a thickness of 50 μm. Here, it is important to make the substrate 101 thin so that it can be easily removed by chemical etching. However, even when the substrate 101 has a thickness of about 50 μm, wrinkling or bending often occurs depending on the handling method. Therefore, as the substrate 101, a substrate in which the above-described conductive metal layer is adhered to the surface of an insulating resin plate having moderate strength with an adhesive may be used in order to facilitate handling. More specifically, for example, a polyethylene terephthalate film (PE) which is an insulating resin having moderate strength and relatively acid resistance and alkali resistance.
T film) as a reinforcing layer, and the above-mentioned thickness, for example, 50 μm
A substrate to which a metal layer such as aluminum is bonded may be used as the substrate 101. When such a laminate is used as a substrate for a transfer medium, the adhesive used is transferred after forming the transfer medium in a later step, or after pressing the obtained transfer medium with an insulating substrate for a wiring substrate. Any adhesive may be used as long as the insulating resin plate (PET film or the like) serving as the reinforcing layer of the transfer medium can be easily peeled from the medium.
As such an adhesive, for example, a foam-peelable resin adhesive using an adhesive containing a foaming agent that foams at about 120 ° C., for example, “Riba Alpha” (trade name of Nitto Denko Corporation) No.

The metal layer 102 for forming the conductive pattern-shaped metal layer 104 thereon is subjected to, for example, surface treatment of the substrate 101 as a surface pretreatment so that plating can be formed in a later step. If the surface is at least aluminum, treat the aluminum surface with a surface treatment solution containing hydrofluoric acid to remove aluminum oxide and dirt, and then electroplate with a solution containing fluoride. A zincate treatment mainly comprising zinc is performed. At this time, the fluoride keeps the aluminum surface always in a clean state and makes the zincate good. Then, in order to attach a metal (here, copper) similar to the metal constituting the conductor wiring as a nucleus for plating, copper pyrophosphate, potassium pyrophosphate, and ammonium hydrogen citrate solution are used in a concentration of 0.5 to 0.5 μm. 3A / dm ²
A relatively high-speed copper electroplating by replacing zincate and copper with a current density of, for example, so-called flash copper. Here, this flash copper is a core of a copper plating to be formed later, and facilitates the growth of plating to which a brightener is added in a later step, and has a very coarse density and a small thickness. Absent. This flash copper can be formed not only by electroplating on aluminum but also by vapor deposition or bonding, in order to form a nucleus that enables pattern plating of the metal layer 104 in a later step. If possible.

Next, as shown in FIG. 1B, a pattern 103 of an insulating resin is formed on the surface of the flash copper as the metal layer 102 to be used as a plating core.
This pattern formation using an insulating resin is usually performed by using a photosensitive resin as a resin, applying or laminating the photosensitive resin so as to cover the entire surface of the metal layer 102, and then performing exposure and development using a predetermined mask or the like. Only the remaining area is left, and the surface of the flash copper as the metal layer 102 is exposed so as to be a pattern symmetrical with the intended conductor wiring pattern. Here, the photosensitive resin has a film type and a liquid type, and the liquid type can form a finer pattern than the film type, and the positive type, in which the photosensitive portion is removed by development, is finer than the negative type. Since a pattern can be formed, it is preferable to employ a liquid type and a positive type. Here, the thickness of the photosensitive resin pattern 103 is the same as the thickness of the conductive metal layer pattern for wiring (metal layer 104
It is preferable that the thickness is larger than (the total thickness of the layers 105 and 105) because a short circuit with a similar conductive metal layer pattern disposed next does not occur. Here, the layer is formed to have a thickness of about 15 μm after development. Since the thickness of the photosensitive resin pattern 103 varies depending on the thickness of the conductive metal layer pattern for wiring as described above, it cannot be specified unconditionally.
It is used in a thickness range of about μm.

Here, the shape of the resin pattern using the photosensitive resin pattern 103 can be faithfully formed as a target wiring line pattern. For example, a linear portion is excellent in linearity, and unevenness in the width direction of the line is reduced. Not only is it small, but also the side wall can be formed with a nearly vertical cross-sectional shape with good reproducibility. Therefore, the conductor wiring can be formed by the subsequent plating with the same size as the opening of the photosensitive resin. This makes it possible to form a conductive wiring pattern made of a conductive material to be formed later with good electrical characteristics and with good reproducibility.

Next, as shown in FIG.
02 in the exposed area of the flash copper as the substrate 101
Is formed by electroplating having a growth direction of the metal agglomerate which is almost parallel to the above. The electroplating of copper for forming the metal layer 104 having a metal particle lump growth direction almost parallel to the substrate 101 is performed by using a mixed solution of copper sulfate 50 to 250 g / l and sulfuric acid 30 to 100 g / l, for example, copper sulfate. 200g /
As a brightener (smoothing agent) to be added to a bright plating plating for decoration in a solution mainly containing a mixed solution of 50 g / l of sulfuric acid to 1 and an additive used for ensuring uniformity, for example, sulfur as a main component “Elecopper 25” (trade name of Okuno Pharmaceutical Co., Ltd.) and additive “CU” to ensure uniformity
PPORAPID Hs "(trade name of LPW, West Germany) and the like, and at a current density of 0.5 to 40 A / dm ² , for example, 2 A
Obtained by plating in / dm ^2.

By adding the brightener and an additive for ensuring uniformity (hereinafter simply referred to as a brightener), the surface tension of the photosensitive resin liquid is reduced and the wettability is improved. The growth of copper by plating has a function of improving the adhesion of plating, because the growth direction of the agglomerates is almost parallel to the surface of the substrate and in a plane shape, enabling easy and uniform plating growth even in fine patterns. Becomes

However, the surface of the pattern formed here is a glossy surface without unevenness due to the brightener.
After being formed as a transfer medium, the aluminum of the transfer medium substrate is removed by etching after press-bonding with the substrate for the wiring board, and when the conductive wiring is formed on the wiring board by transfer, the adhesive strength of the conductive wiring is reduced. And peels off. However, if the plating is performed with a solution mainly composed of copper sulfate containing no brightener in this step instead of the above plating conditions in order to roughen the surface of the metal layer by plating, copper is sparse. As a result, the metal pattern becomes island-shaped or broken inside, so that a fine conductor wiring pattern cannot be formed.

Then, as shown in FIG. 1 (D), electroplating with another solution is performed so that the growth direction of the metal particles is substantially perpendicular to the surface of the substrate 101.
Copper plating is performed on the metal layer 104 to form a metal layer 105 whose growth direction of metal particles is substantially perpendicular to the surface of the substrate 101. The electroplating of copper for forming the metal layer 105 in which the growth direction of the metal particles is substantially perpendicular to the surface of the substrate 101 is performed by adding the above-mentioned brightener or the like to the plating solution mainly containing copper sulfate and sulfuric acid. 0.5-
This is achieved by plating at a current density of 40 A / dm ² , for example at 2 A / dm ² .

Here, since the copper constituting the metal layer 104 having the growth direction of the metal particles in a direction substantially parallel to the substrate 101 is already formed in the fine pattern portion, this acts as a plating nucleus. Therefore, the metal layer 105 in which the growth direction of the metal particles is substantially perpendicular to the surface of the substrate 101 can be formed in a similar fine pattern. Since the growth direction of the metal particles of the copper layer as the metal layer 105 formed at this time is nearly perpendicular to the substrate, the copper layer is microscopically formed into islands, and the copper formed in these islands is formed. Are connected in the plane direction, so that fine irregularities are formed on the surface and the surface is roughened. still,
After this plating, the photosensitive metal is slightly etched with a copper metal grain boundary etching solution, such as a mixed solution mainly composed of copper sulfate and hydrogen peroxide, which is generally marketed as a solution for browning or the like. The metal grain boundaries only on the surface of the formed metal layer 105 which are not protected by the resin are etched to emphasize the valleys. Therefore, the surface of the formed metal layer 105 can be further roughened. At this time, since the side surfaces of the metal layers 104 and 105, which are the copper patterns formed by plating, are covered with the resist, which is a photosensitive resin, the target pattern is faithfully reproduced, and is not intended in the width direction of the pattern. There is no unevenness, for example, the linear pattern portion can be roughened more deeply only on the upper surface of the metal layer 105 without change in good linearity, and the side wall side of the pattern is etched like etching. There is no change in pattern dimension due to such side etching.

Thereafter, as shown in FIG. 1E, the photosensitive resin pattern 10 is removed with a removing solution such as a sodium hydroxide solution.
3 is dissolved away. As a result, the surface of the copper as the metal layer 105 is roughened, and the finely patterned metal layers 104 and 105 having good linearity on the pattern side walls of the metal layers 105 and 104 are formed on the aluminum substrate 101. A transfer medium is obtained. When removing the aluminum substrate later, here, the patterned metal layer 104,
Since 105 is copper and the etching solution is different from that of the aluminum substrate 101, only the aluminum substrate can be removed by chemical elution or decomposition selectively, that is, only the aluminum substrate can be selectively removed by chemical etching. A possible transfer medium is obtained.

Next, a metal layer 104, 10
A substrate for a wiring board for transferring 5 into a wiring board will be described with reference to sectional process drawings.

That is, as shown in FIG. 2F, as the insulating substrate 201 for the wiring substrate, for example, a polyimide film among imide-based films and the like excellent in electrical characteristics such as reliability such as heat resistance and insulation and high frequency characteristics is used. Is adopted. Although this can be made thin by being a film, it is also possible to use a nonwoven fabric of synthetic fibers or a fiber reinforced plastics plate in which glass fibers are impregnated with an epoxy resin.

An epoxy resin is used as an adhesive 202 that can be adhered to both sides of the polyimide film as the insulating substrate 201 by pressing in a later step, so that the plating thickness of the fine conductor wiring metal layers 104 and 105 of the transfer medium is increased. The through-hole 203 is formed in a necessary portion by irradiating a laser beam or the like.

Then, as shown in FIG. 2G, the formed through-hole 203 is filled with a conductive paste 204. The conductive paste 204 is obtained by kneading metal powder such as copper powder, silver powder or gold powder, or fine particles obtained by coating metal on the fine particles of a resin with a paste resin or a solvent. 20
Filling 4 is performed by a method such as printing or press fitting.

Thereafter, as shown in FIG. 3, the transfer medium (h) separately formed as described above and the transfer medium (j) having a different pattern formed separately as described above face each other,
In the middle thereof, a paste 204 is filled in the through hole 203 shown in (i), and an insulating substrate 201 for a wiring substrate made of a polyimide film coated with an adhesive 202 is superposed. At this time, if necessary, the lands of the conductor wiring metal layers 104 and 105 of the transfer medium disposed on both sides are aligned with the through holes 203 filled with the conductive paste 204.

Then, pressure bonding is performed as shown in FIG. This press-bonding is performed by heating together with pressurizing, so that the adhesive 202
And the epoxy resin of the adhesive 202 is cured. Further, the metal layers 104 and 1 for the conductor wiring of the transfer medium aligned by the pressurization.
The land portion 05 and the conductive paste 204 in the through hole 203 filled with the conductive paste 204 are pressed together, and the conductive wiring metal layers 104 and 105 on both surfaces are electrically connected. Hereinafter, the metal layer for conductor wiring is simply referred to as conductor wiring. Here, since the surfaces of the conductor wirings 104 and 105 are roughened, there is also an effect of increasing the contact area with the metal powder in the conductive paste 204, whereby the connection resistance can be reduced.

Thereafter, as shown in FIG. 5, the aluminum which is the substrate 102 for the transfer medium on both sides is removed by etching with hydrochloric acid. Here, depending on hydrochloric acid, only aluminum and zincate can be selectively etched without etching copper, so that fine copper wiring 10
4, 105 has no effect at all, and the conductor wiring 104,
Only aluminum and zincate are selectively removed without etching 105. Further, the flash copper as the metal layer 102 is removed by etching using an aqueous ammonium persulfate solution of 20 g / l. In this case, since the flash copper is very thin and rough, it can be removed in a very short time, and there is almost no effect on the fine copper conductor wirings 104 and 105. Note that aluminum, which is a substrate for the transfer medium, may be removed on one side only in a later step.

A wiring board having a fine pattern can be obtained by the method described above. In the above method, after the zincate treatment and flash copper are formed on the surface of the aluminum substrate 101 as the transfer medium, the photosensitive resin pattern 10 is formed.
Then, the metal layers 104 and 105 were sequentially formed by plating in the form of a fine copper wiring pattern. After the zincate treatment was performed on the surface of the aluminum substrate 101 as the transfer medium, the photosensitive resin pattern 103 was formed. And forming flash copper on the exposed surface of the zincate treatment,
Thereafter, the conductor wirings 104 and 105 may be sequentially formed by plating a fine copper pattern. In this case, aluminum and zincate can be selectively removed simultaneously only by etching with a hydrochloric acid solution. Not only can the process be shortened, but the copper pattern 104,
105 has no effect.

By using a photosensitive polyimide, for example, a photosensitive insulating polyimide resin such as "PIQ" (trade name of Hitachi Chemical Co., Ltd.) as the photosensitive resin 103, the conductive resin can be formed at the stage of FIG. After the formation of the plating of the wirings 104 and 105, the photosensitive insulating polyimide resin can be used as a transfer medium without removing the photosensitive insulating polyimide resin, that is, without going through the process shown in FIG. It is. That is, in this case, the polyimide resin, which is the photosensitive resin 103, is transferred to the wiring board together with the conductor wirings 104 and 105. However, unlike the usual photosensitive resin, the photosensitive insulating polyimide resin has excellent insulation properties, so it is transferred to a substrate for a wiring board without being removed and serves as an insulating layer between conductor wiring. It is also possible to fulfill.

[0066]

According to the present invention, in the wiring board, the metal wiring pattern has excellent adhesion to the insulating substrate, the circuit constant does not vary, the uniformity is maintained, the high-frequency characteristics are stable, and the variation in the high-frequency characteristics is improved. Conductor wiring substrate with good product yield even if a fine wiring pattern is formed, a transfer medium for transferring conductive wiring to an insulating substrate of the conductive wiring substrate, and a large-scale facility or complicated process And a method of manufacturing a conductive wiring board and a transfer medium having the above-described excellent performance relatively easily without the need for the method.

As described in the detailed description of the invention, the present invention uses a transfer medium that can selectively remove a substrate for a transfer medium by chemical elution or decomposition without mechanical peeling. Therefore, the transfer medium substrate is not mechanically peeled off after the transfer. Therefore, the fine wiring can be transferred and formed without applying a mechanical stress to the conductor wiring. The growth direction of the metal particles in the metal layer under the conductor wiring of the transfer medium is almost parallel to the substrate surface, and The lower surface is composed of a smooth surface metal layer, the metal granule growth direction of the upper metal layer is almost perpendicular to the substrate surface, and the upper surface of the upper metal layer is a roughened surface. In addition, since the fine conductor wiring can be formed by plating and the surface is roughened, it is possible to obtain a transfer medium capable of improving the peel strength of the conductor wiring of the wiring board obtained after the transfer. . The conductor wiring of the transfer medium having such a structure is obtained by electroplating a substrate patterned with a photosensitive resin with an electroplating solution in which additives such as a brightener and a smoothing agent are mixed, and then performing electroplating without the additives. By plating continuously with liquid,
It can be obtained relatively easily without large equipment and complicated processes. By using copper as the conductor wiring, not only the electric resistance is low but also generally simpler plating technology such as decoration and surface protection, that is, simple improvement of plating in a field completely different from fine wiring formation. Plating is possible with technology. Moreover, after the transfer medium is pressed against the insulating substrate for the wiring board, the transfer medium can be selectively removed by etching that chemically dissolves or decomposes the transfer medium. Thus, it is possible to obtain a wiring board having various conductor wirings. And
In the obtained wiring board, fine plated wiring with a roughened lower layer surface has high pattern fidelity and good side wall linearity, as in the case of photosensitive resin, and the upper layer has metal in the direction parallel to the current. Since the metal layer has a direction in which the aggregates grow, a wiring having good electric characteristics, particularly high-frequency characteristics, can be obtained. Further, the conductor wiring whose lower side surface is roughened is connected to the conductor paste filled in the penetrated through-hole by pressure welding, and the conductive paste is formed on the unevenness of the conductor wiring of the lower metal layer. Not only can reduce the contact resistance, but also thermal expansion due to temperature cycling,
The reliability can be improved because the contact point moves with respect to the heat shrinkage stress and the electrical connection is maintained. Furthermore,
Since at least a part of the conductor wiring is buried, a wiring substrate having a further increased peel strength of the conductor wiring from the substrate can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a process for manufacturing a transfer medium according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a process of manufacturing an insulating substrate for a wiring board according to one embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing a transfer and pressure bonding step for manufacturing a wiring board according to one embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view showing a stage after transfer and pressure bonding for manufacturing a wiring board according to one embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view of a wiring board according to one embodiment of the present invention.

[Explanation of symbols]

 101: Transfer medium base material 102: Deposition layer of the same metal as the metal constituting the conductor wiring 103: Photosensitive resin pattern 104: Metal layer 105: Metal layer 201: Insulating substrate for wiring substrate 202: Adhesion Agent 203: Through hole 204: Conductive paste

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Nakamura 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 4E351 AA18 BB01 BB22 BB24 BB26 BB27 BB29 BB35 CC17 CC18 CC19 DD01 DD54 GG01 5E343 AA02 AA11 AA38 BB02 BB15 BB21 BB66 DD56 DD62 ER49 GG04 GG08

Claims (16)

[Claims] 1. A conductor wiring is formed at least partially buried in an insulating substrate in a thickness direction thereof, and an upper surface of an upper layer portion of a metal layer forming the conductor wiring is substantially smooth. A wiring substrate, wherein the lower surface of the lower layer portion is a roughened surface. 2. The method according to claim 1, wherein the metal layer forming the conductive wiring is composed of a plurality of layers, the growth direction of the metal particles in the upper metal layer is substantially parallel to the surface of the insulating substrate, and the metal particles in the lower metal layer are 2. The wiring substrate according to claim 1, wherein the bulk growth direction is substantially perpendicular to the surface of the insulating substrate. 3. The wiring board according to claim 1, wherein irregularities on the lower surface of the lower metal layer are further roughened. 4. The insulating substrate according to claim 1, wherein the insulating substrate is formed of a resin film having an adhesive layer adhered to a surface portion thereof, and the conductor wiring is embedded in the adhesive layer. The wiring board as described. 5. A metal layer is formed on a transfer medium substrate having at least a surface having conductivity in a pattern symmetrical to a pattern to be a conductor wiring, and a metal layer is formed under the metal layer. A transfer medium for transferring and forming conductive wiring on an insulating substrate, characterized in that the side surface is substantially smooth and the upper surface of the upper layer portion is a roughened surface. 6. A metal layer formed in a pattern symmetrical to a pattern to be a conductor wiring in a plane symmetrical manner, wherein a plurality of layers are formed, and a growth direction of metal particles in a lower metal layer is substantially parallel to the substrate surface; 6. The transfer medium according to claim 5, wherein the direction of growth of the metal particles in the upper metal layer is substantially perpendicular to the surface of the substrate. 7. The transfer medium according to claim 5, wherein the irregularities on the upper surface of the upper metal layer are further roughened. 8. A metal similar to a metal constituting a conductor wiring to be formed later is formed on a transfer medium substrate, and a pattern which is plane-symmetric with a pattern to be a conductor wiring is formed on the metal mounting surface. The transfer medium according to claim 6, wherein the metal layer including the plurality of layers is formed in a shape. 9. The transfer medium according to claim 5 and an insulating substrate are pressure-bonded, and the conductor wiring formed on the transfer medium is transferred to the surface of the insulating substrate and is transferred in the thickness direction. A method for manufacturing a wiring board, comprising: a step of transferring at least a part of the transfer medium so as to be embedded; 10. An insulating substrate on which a transfer medium is pressed,
The wiring board according to claim 9, wherein the wiring board is a resin film having an adhesive layer adhered to a surface layer portion thereof, and the transfer medium and the insulating substrate are pressure-bonded so that the conductor wiring is embedded in the adhesive layer. Manufacturing method. 11. A step of selectively exposing a substrate surface free of the resin by forming a desired resin pattern on the substrate surface of a transfer medium substrate having at least a surface having conductivity; 7. The method for producing a transfer medium according to claim 5, further comprising the steps of: forming a bright plating on the surface of the substrate; and then forming a non-glossy plating thereon. 12. A step of depositing and forming a metal similar to a metal constituting a conductive wiring to be formed later on a surface of a transfer medium substrate having at least a surface having conductivity, and the deposited metal Selectively exposing the metal surface free of the resin by forming a desired resin pattern on the surface; forming bright plating on the exposed metal surface; and then applying non-glossy plating thereon. 9. The method for manufacturing a transfer medium according to claim 8, further comprising the step of: 13. The method for producing a transfer medium according to claim 11, wherein the bright plating and the non-glossy plating of the transfer medium are electroplating. 14. The bright plating is plating using a plating solution containing a brightener, and the non-glossy plating is plating using a plating solution containing no brightener. Method for producing a transfer medium. 15. The method of claim 1, wherein after the formation of the non-glossy plating, a roughening treatment is performed so that the unevenness of the exposed surface of the formed non-glossy plating layer is further roughened, and then the resin formed in a pattern is removed. Item 15. The method for producing a transfer medium according to any one of Items 11 to 14. 16. The method according to claim 15, wherein the roughening treatment is metal grain boundary etching.