JPH04176186A - Manufacture of double sided wiring board - Google Patents

Abstract

PURPOSE:To obtain a double sided wiring board by a method wherein an insulating resin film provided with a metal layer of copper or the like on each side without using adhesive agent is made to serve as a base, a prescribed wiring is provided to the upside and the underside of the base respectively, and the wirings are electrically connected together through a viahole formed in the insulating resin film. CONSTITUTION:A base metal layer of copper is formed on both the sides of a polyimide resin film base through a copper electroplating method, photosensitive resist is applied onto each of the base metal layers, exposed to light by irradiating it with ultraviolet rays through the intermediary of a photomask, and then developed. At this point, the lower resist layer is exposed to light through a photomask provided with a viahole corresponding to the upper wiring pattern. Then, the base copper laser exposed on the underside of the film base is dissolved, on the other hand, a pre-wiring is formed on the upside of the film base through a copper electroplating method, the resist layers on the sides of the film base are removed, wirings are formed by dissolving the base copper layer on the upside, both the sides of the base film are coated with an organic resin film, the exposed part of polyimide resin of the underside is dissolved to form a prescribed viahole, wirings are formed on the underside the same as the upside of the base film, the organic resin film is removed by separation, and the upper and the lower wirings are electrically connected together through the viahole.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a double-sided wiring board to be mounted on an electronic component, and more specifically to manufacturing a flexible wiring board having wiring on both sides of an insulating resin base. It is about the method.

(Prior Art) In recent years, the electronics industry has been rapidly developing multifunctional devices with low cost and high reliability. There is an increasing demand for small devices that have multiple functions, are lightweight, and thin. Accordingly, the development of new element mounting technology is becoming more important day by day, and even for wiring boards, thick and rigid wiring boards such as previous glass epoxy boards and phenolic resin boards are lighter. , it is no longer possible to meet the demand for thin devices, and so-called flexible wiring boards, in which wiring is formed on high-performance and highly flexible film-like substrates such as engineering plastics, have become mainstream.

However, it is technically extremely difficult to efficiently form a copper pattern, which is a wiring material, directly on a highly flexible plastic film, so an alternative technique is to use an adhesive to attach copper foil in advance. The commonly used method was to bond the wire to a plastic film, and then form a wiring pattern on the plastic film using resist pattern processing technology and etching technology.

However, when using polyimide film as the plastic, for example, the heat resistance of the adhesive is extremely low, so when using this as a product, it is difficult to effectively utilize the excellent heat resistance properties of polyimide film. I couldn't do it.

However, recently, several methods have been developed for directly forming a metal layer on a plastic film without relying on an adhesive, as described below. The methods include: (1) A method of coating a plastic film with a metal film using a dry metal film forming method such as sputtering, vacuum evaporation, or CVD.

(2) A method of coating a metal film on the Plus Deck film by a wet metal film forming method such as electroless plating.

(3) A method in which a precursor of a resin component for forming a plastic film is formed into a layer on a metal foil and then heated to convert the precursor into a plastic film.

and so on. By implementing these methods, it has become possible to manufacture flexible wiring boards that meet demand.

However, in recent years, the trend toward higher density mounting technology has become more and more pronounced, and there is a demand for multifunctionality by wiring both sides of the board and connecting some of the wiring on both sides using through poles.

Furthermore, with the increasing demand for high-density substrates, there is also a demand for further minimization of lead widths in wiring patterns on wiring boards.

<Problems to be Solved by the Invention> It is expected that the demand for miniaturization of lead widths as described above will become more intense in the future. It is extremely difficult to form a

Therefore, it is desired to establish a chemical processing technique that can form through holes with high precision.

The present invention was made based on the above-mentioned needs, and an object of the present invention is to provide a new method for obtaining a double-sided wiring board in which wiring on both sides of the board is connected by a minute through hole using a chemical method. It is something to do.

(Means for Solving the Problems) The present invention for achieving the above object is constituted by the following basic steps.

That is, the method for manufacturing a double-sided wiring board according to the present invention uses an electrically insulating synthetic resin (hereinafter referred to as "insulating resin") such as polyimide.
The base is a film with metal layers formed on both sides without using an adhesive. After forming a photosensitive resist layer on the metal layers on both sides of the base, a predetermined wiring pattern is mainly formed on the resist layer on the top surface of the base. A photomask having a predetermined via hole pattern is applied to the resist layer on the lower surface of the substrate, and after irradiation with light, the resist layers on both sides are developed, and a resist pattern of each shape is formed on both sides of the substrate. A step of forming a predetermined wiring on the upper surface of the substrate by performing a wiring forming process on the upper surface of the substrate according to the resist pattern formed on the upper surface of the substrate, and a step of forming a predetermined wiring on the lower surface of the substrate according to the resist pattern formed on the lower surface of the substrate. A step of melting a portion of the metal layer to expose an insulating resin, and then melting the exposed portion of the insulating resin to form a predetermined via hole, and forming a metal thin film layer on the bottom surface of the substrate after the via hole is formed. After that, a photosensitive resist layer is formed again on the metal thin film layer, a photomask having a predetermined wiring pattern is applied on the resist I-layer, irradiated with light, and then developed to form a resist pattern on the lower surface of the substrate. The process consists of forming a predetermined wiring on the bottom surface of the substrate by carrying out a wiring formation process according to the resist pattern, and electrically conducting the predetermined wiring formed on the top and bottom surfaces of the substrate through via holes formed in the insulating resin substrate. The feature is that through-holes are formed by

In the present invention, different methods are used for forming the wiring on the upper surface of the substrate depending on the thickness of the metal layer applied on the upper surface of the substrate in advance.

That is, when the metal layer applied to the upper surface of the substrate is a thin so-called base metal layer, a metal plating layer is laminated by electroplating on the exposed base metal layer according to a resist pattern formed on the upper surface of the base. After forming a wiring surface shape on the laminated metal layer, a so-called semi-additive method is applied to form wiring by dissolving the resist on the top surface of the substrate and the underlying metal layer existing thereunder, and then forming a wiring surface on the top surface of the substrate. If the thickness of the metal layer to be applied is initially formed to be comparable to the height of the desired wiring, after etching the exposed metal layer according to the resist pattern formed on the top surface of the substrate, A so-called subtractive method is used in which wiring is formed by simply dissolving and removing the resist on the non-etched metal layer.

In addition, via holes are formed in the insulating resin substrate by a so-called etching method in which the exposed metal layer is etched according to a resist pattern formed on the bottom surface of the substrate to expose the insulating resin portion, and the exposed portion of the insulating resin is dissolved and removed. Alternatively, a metal plating layer is laminated by electroplating on the exposed metal layer according to the resist pattern to form a metal pattern of the laminated metal, and then the resist and the metal layer existing under the resist are dissolved and removed, A so-called semi-additive method is used to dissolve and remove the exposed insulating resin, but another method is to etch the exposed metal layer according to a resist pattern formed on the bottom surface to remove the insulating resin part. After exposure, the resist pattern is removed to expose the metal layer under the resist, a metal plating layer is deposited on the exposed metal layer by electroplating, and the exposed portion of the insulating resin is dissolved and removed using an etching method and a semi-adhesive method. This can be carried out by using either a combined method with a multilayer method.

As described above, in the present invention, wiring is formed on both the upper and lower surfaces of the substrate, and the wiring on the upper surface and the wiring on the lower surface are partially electrically connected through via holes. After forming the via hole, a metal thin film layer is formed on the lower surface of the substrate, a photosensitive resist layer is again formed on the metal thin film layer, a photomask having a predetermined wiring pattern is applied on the resist layer, and exposed and exposed. A resist pattern is formed again by performing this process, and a metal plating layer is deposited by electroplating on the exposed metal thin film layer according to the resist pattern formed again in this way, and then the resist layer is dissolved and removed. Either by a semi-additive method that dissolves and removes the underlying metal thin film layer and the metal layer existing thereunder, or by laminating a metal plating layer by electroplating immediately on the metal thin film layer formed on the bottom surface of the substrate after the via hole is formed. A subtractive method is used in which a laminated metal layer is formed, a resist pattern is then formed again in the same manner as above, the exposed laminated metal layer is dissolved and removed according to the resist pattern, and the remaining resist is further dissolved and removed. Either method will be adopted.

As mentioned above, there are several methods for forming wiring on the upper and lower surfaces of the substrate and forming via holes in the insulating resin, but in the present invention, the desired results can be achieved by appropriately combining these methods. A double-sided wiring board with high performance can be easily obtained.

(Function) Next, details of the method for manufacturing a double-sided wiring board according to the present invention and its function will be explained based on the drawings.

FIG. 1 shows a basic process diagram of the method for manufacturing a double-sided wiring board of the present invention.

As shown in FIG. 1, the process of the present invention involves forming a metal layer on both sides of an insulating resin film without using an adhesive, using this as a base, and forming respective wiring and via holes on both sides of the base. A step of forming each resist pattern for the substrate, a step of forming upper surface wiring according to the resist pattern formed on the upper surface of the substrate, a step of forming a via hole according to the resist pattern formed on the lower surface of the substrate, and a step of forming the lower surface of the substrate after forming the via hole. It consists of each step of the bottom wiring formation process performed on the
In addition, the wiring formation method used in each process is either a semi-additive method or a subtractive method, and the via hole formation method is an etching method, a semi-additive method, or a combination of both. This is what we do.

FIGS. 2(a), (b) and 3(a), (b) are schematic diagrams of processing steps in the case where upper surface wiring is performed by semi-additive method and subtractive method, respectively, on a double-sided wiring board according to the present invention. FIG. 4 is a step-by-step diagram illustrating the process step by step, and FIG. 4 is a partial plan view showing the appearance of one example of a double-sided wiring board obtained by the present invention.

(a) in Figures 2 and 3 is X in Figure 4.
-Y section, and (b) is a sectional view of a portion corresponding to the X=Y' section.

In FIGS. 2 and 3, (a) and (b) are shown on the same side on the left and right ((g) to (g) represent the state of the cross section of the material in the same process.

In addition, the (opening) in the second stage of the process explanatory diagram indicates the case where the copper layer pattern on the bottom surface of the substrate for forming via holes was formed by the etching method, and the (opening) indicates the case when the semi-additive method was used. In addition, () shows a cross-sectional view when both the etching method and the semi-additive method are used, and (e) and (f) in the fifth and sixth rows show the semi-additive method for forming the bottom wiring. (H") and (H°) show the cross-sections when the subtractive method was used.

FIG. 5 shows an example of a photomask for forming a wiring pattern applied to the upper surface of a substrate in the present invention, and FIGS.
Each figure shows an example of a photomask for forming a via hole pattern.

Furthermore, FIGS. 8 and 9 each show an example of a photomask for forming a wiring pattern applied to the lower surface of a substrate in the present invention.

In FIGS. 2 and 3, 1 is an upper metal layer, 2 is a lower metal layer, 3 is an insulating resin substrate, and 4 and 5 are photosensitive resist layers formed on the upper metal layer 1 and the lower metal layer 2, respectively. be.

6 and 7 are resist layers 4 and 5 on the upper and lower surfaces, respectively.
These are various resist patterns formed by masking, exposing and developing according to a predetermined purpose.

8 is a wiring having a desired pattern formed according to the resist pattern 6 on the upper surface, and 9 is an organic resin coating layer that covers the entire upper surface after the wiring 8 is formed. 10 is a metal layer pattern formed according to the resist pattern 7 on the lower surface.

11 is the formation of the metal layer pattern 10 on the lower surface of the substrate=
This is a via hole obtained by melting the insulating resin exposed by 16-.

Reference numeral 12 denotes a metal thin film layer deposited on the entire lower surface of the substrate after the via poles are formed. 13 is a resist layer formed on the lower surface of the substrate after forming the metal thin film layer 12, and 14 is a resist pattern obtained by exposing and developing the resist layer 13.

The pin 15 is a lower wiring formed on the lower surface of the substrate so as to be electrically connected to a part of the wiring 8 on the upper surface via the via hole 12.

Next, regarding the manufacturing method of the double-sided wiring board of the present invention, each of the steps of forming metal layers and resist patterns on both sides of the substrate, forming wiring on the upper surface of the substrate, forming via holes on the lower surface of the substrate, and forming wiring on the lower surface of the substrate will be described. The process will be explained step by step.

Formation process of metal layer and resist pattern: In the present invention, basically, a tape-shaped insulating resin film is used as the base 3, with metal layer 1 and metal layer 2 formed on both upper and lower surfaces without using an adhesive. be done. Insulating resins that can be used in the present invention include polyimide resins, acrylic resins, polyamide resins, fluorocarbon resins, polysulfone resins, polyimide amide resins, silicone resins, and the like.

The metal layers 1 and 2 to be formed on both the upper and lower surfaces of the insulating resin film base 3 may be formed on the surface of the base by sputtering, vacuum evaporation, electroless plating, or a combination of these methods. These methods may be further combined with an electrolytic plating method, and in short, any method can be employed as long as it forms a metal layer directly on the insulating resin substrate without applying an adhesive.

Furthermore, copper is generally used as the metal layer formed on the substrate 3 from the viewpoint of electrical performance and cost, but even if there is a thin film layer of other metals such as chromium or nickel between the polyimide substrate and the copper, there will be no problem. No problem.

In addition, when the wiring is formed by a semi-additive method, the thickness of the metal layer 1 formed on the top surface of the substrate is such that it can withstand soft etching in the pre-treatment during the formation of the electroplated layer that is performed when forming the wiring. There is no particular restriction, but in view of the workability of the partial melting process of the upper surface metal 1 for independent wiring as will be described later.
．． The thickness is preferably in the range of 5 to 2 μm.

Further, when the wiring is formed by a subtractive method, the thickness of the upper metal layer 1 must be made equal to the desired wiring thickness before the resist layer 4 is formed. Therefore, the metal layer is formed by first forming a metal thin film layer on the top surface of the insulating resin substrate using the sputtering method described above, and then depositing plated metal on the top surface by electroplating until a predetermined thickness is reached. It is better to do so. The thickness of the wiring normally required is up to about 35 μm.

In addition, the thickness of the metal layer 2 formed on the lower surface of the substrate is determined by etching when forming a metal layer pattern for forming a predetermined via hole in an insulating resin.
Since the metal layer 2 plays a role similar to a resist in the subsequent melting process of the insulating resin, it must be able to withstand the solution for dissolving the insulating resin at a temperature of -1,9- and avoid pin-pole defects. Considering that it is necessary to take into account the dissolution of the insulating resin in unnecessary parts and the prevention of peeling of the metal layer 2 from the base, and the ease of dissolution in the dissolution process of the metal layer 2 after forming the resist pattern, etc. It is desirable that the thickness be in the range of about 5 μm.

In addition, when forming a metal layer pattern by a semi-additive method, as described later, after forming a resist pattern,
Since overlay is performed on the metal layer 2 by electroplating, the thickness of the metal layer 2 only needs to be thick enough to withstand soft etching during pre-treatment of electroplating, and there is no particular restriction, but the thickness may be applied after electroplating. Considering the ease with which the metal layer 2 can be dissolved in the melting process], the thickness is preferably less than 9 μm, and the appropriate thickness is 0.2 to 1 μm.

Furthermore, when using both the etching method and the semi-additive method, the thickness of the metal layer 2 is reduced to 0 for the same reason.
．． It is desirable to set it as the range of 1-1 micrometer.

The thickness of the resist layer 4 formed on the top surface of the substrate must be greater than 35 μm since the wiring is required to have a thickness of 35 μm or more when the wiring is formed by a semi-additive method. There is a need to. Further, when the wiring is formed by a subtractive method, there is no particular limitation on the thickness, but in consideration of the pattern accuracy after dissolving the metal layer 1 after forming the resist pattern 6, a thickness of about 1 to 10 μm is appropriate.

The type of resist is one that can be applied to the above thickness, and is suitable for electroplating or melting of metal layer 1 when forming wiring on the upper surface and melting of metal layer 2 when forming a metal layer pattern on the lower surface. General commercially available products are sufficient as long as they can withstand the plating solutions and metal solutions used in acrylic resins, etc. By adding photosensitive functional groups to acrylic resins, etc., the light-irradiated areas can be undissolved during development. There are negative-tone resists that remain as parts, and positive-tone resists in which the light-irradiated areas dissolve during development by adding a photosensitive functional group to the novolac resin, etc. However, by reversing the pattern of the photomask, it is possible to It can also be used with other resists. In addition, either a liquid state or a solidified dry film state can be used.

When using a liquid resist, coating onto the base metal layer of the substrate can be done by general coating methods such as bard method, dip method, spin method, etc., or by charging the resist liquid and applying it in a spray form. An electrostatic coating method may also be used.

The solution for the metal layers 1 and 2 is generally an acidic solution such as hydrochloric acid, sulfuric acid, or nitric acid, a metal chloride solution such as an iron chloride solution or a copper chloride solution, or a peroxide solution such as an ammonium persulfate solution. Since solutions are used, the resist only needs to be able to withstand these solutions.

Further, an alkaline solution is sometimes used as the dissolving solution, but in this case, an alkali-resistant resist may be used.

Generally, in order to form a pattern using a resist, it is necessary to remove the solvent contained in the resist after applying the resist. This is done to improve the strength of the resist itself and at the same time to increase the adhesion between the resist and the underlying metal.The solvent is usually removed by drying, but the processing temperature at this time depends on the resolution of the resist. It is best to set it as high as possible without lowering the value.

Further, in order to make the formed pattern stronger after exposure and development, a heat treatment is sometimes performed, but in this case, a temperature higher than that used in the above-mentioned solvent drying treatment is employed.

Next, a photomask with a desired pattern is applied to the resist layers 4 and 5 formed on the metal layer, each is irradiated with an appropriate amount of light and developed, and a resist pattern is formed on the base metal layer. 6, and a resist pattern 7 is formed on the base metal layer 2. A first mask is applied to the resist layer 4 on the upper surface of the substrate so that a wiring pattern will be formed after development, and a mask is applied to the resist layer 4 on the lower surface. 5, a photomask on which a via hole pattern is mainly formed is used.

The photomask for forming the wiring pattern on the upper surface of the substrate includes, for example, the one shown in FIG. 5, but it may also have a hole pattern such as a sprocket hole.

Further, as a photomask for forming a via hole pattern on the lower surface of the substrate, for example, a photomask shown in FIG. 6 or an inverted version of the photomask shown in FIG. 7 can be cited.

Although the wavelength of the light irradiated to expose the resist is determined by the characteristics of the resist, ultraviolet rays are generally used. Furthermore, the photomask referred to herein refers to one in which an emulsion containing silver or a metal such as chromium is baked onto glass or a translucent plastic film.

There are two types of exposure methods: a contact exposure method in which the resist surface and a photomask are brought into close contact with each other, and a projection exposure method in which the resist surface and the photomask are arranged parallel to each other at a certain distance. may be adopted.

(See Figure 2 and Figure 3 (a), (o), (0“
) and (2) Formation process of wiring on the upper surface of the substrate: Either a semi-additive method or a subtractive method is explored for forming wiring on the upper surface of the substrate.

In order to form wiring by a semi-additive method, a metal layer 1 formed according to a resist pattern 6 formed on the upper surface of the substrate is used.
After forming a wiring preform by laminating a metal plating layer on the exposed portion of the metal layer by electroplating so that the metal layer after lamination has the desired wiring thickness, that is, a thickness of 35 μm or more, the resist pattern 6 is dissolved and removed. Furthermore, the metal layer 1 on the upper surface of the substrate after the resist pattern has been removed is dissolved and removed to make the wiring 8 electrically independent.

Further, when wiring is formed by a subtractive method, the wiring 8 is formed by dissolving the exposed portion of the metal layer 1 that is generated according to the resist pattern 6 formed on the upper surface of the substrate. The metal layer 1 may be dissolved using either a dipping method or a spray method, or a combination of these methods may be used.

After the wiring is formed, an organic resin film 9 is applied over the entire upper surface of the substrate. This coating with the organic resin film 9 has the role of protecting the insulating resin exposed on the surface in the subsequent process. The organic resin used in this organic resin coating step may be any material as long as it can withstand the insulating resin solution used in dissolving a predetermined portion of the insulating resin in the subsequent via pole forming process. When polyimide resin is used as the insulating resin, a strong alkaline solution is used as the solution thereof, so organic resins such as rubber-based, epoxy-based, silicone-based, etc. may be used.

(See Figures 2 and 3 (B), (D'), (C) and (C) above) Three forming steps for via holes: A predetermined portion of the insulating resin is melted to form via holes 11.
For forming the metal layer pattern on the lower surface of the substrate, an etching method, a semi-additive method, or a combination of both methods is employed.

When the metal layer pattern 10 for forming via holes is formed by etching, the metal layer pattern 10 is first formed by dissolving the exposed portion of the metal layer 2 formed according to the resist pattern 7 formed on the lower surface of the substrate. Via holes 11 are formed at predetermined positions by melting the exposed portions of the insulating resin 3 resulting from the formation of the metal layer pattern 10.

When Voymide resin is used as this insulating resin, it can be dissolved by hydrating it and using a strong alkaline solution such as drazine, alkali hydroxide alone or in combination, and methyl alkaline,
This may be carried out using a mixed solution of ethyl alyl, propyl alyl, etc.

When the metal layer pattern 10 is formed by a semi-additive method, the exposed portion of the metal layer 2 formed in accordance with the resist pattern formed on the lower surface of the substrate is electroplated to build up the plating metal.

The metal layer after this electroplating plays a role similar to a resist in the insulating resin melting process described later, so it naturally needs to be able to withstand the insulating resin solution. Furthermore, the thickness must be determined in consideration of melting of unnecessary portions of the insulating resin due to defects such as pinholes, and prevention of peeling of the metal layer 2 during melting work. In this sense, the thickness of the metal layer after lamination of plated metal by electroplating is 2 μm or more,
Preferably, the thickness is in the range of about 2 to 5 μm. Thereafter, the resist pattern 7 and the metal layer 2 existing thereunder are dissolved to form the metal layer pattern 10. Next, the exposed portion of the insulating resin 3 resulting from the formation of the metal layer pattern 10 can be dissolved to form the via hole 11.

In addition, when forming the metal layer pattern 10 for forming via holes by using a combination of etching method and semi-additive method, the exposed portion of the metal layer 2 is melted according to the resist pattern formed on the lower surface of the substrate. Next, the resist of the resist pattern 7 is dissolved to expose the underlying metal layer 2, and a metal layer is deposited thereon by electroplating to form a metal layer pattern. As mentioned above, it is appropriate that the thickness of the metal layer pattern 10 after lamination at this time is about 2 to 5 μm. It is also the same as the case described above that after forming the metal layer pattern 10, the exposed portion of the insulating resin 3 is melted to form the via hole 11.

Further, as a method of forming a predetermined via hole 11 by removing the insulating resin exposed by forming the metal layer pattern 10, the substrate is immersed in a solution that can dissolve the exposed insulating resin, and the exposed portion is dissolved. In addition to so-called wet etching, there is a method of optically removing the exposed portions by irradiating the exposed insulating resin with a laser beam.

In this method of using a laser beam, it is possible to use a carbon dioxide laser or an excimer laser, but in this case, care must be taken not to damage the metal layer pattern 10, which plays a similar role as a mask. It is necessary to adjust the power. In addition, beer hall 11
When using a method of forming by laser,
Formation of the organic resin film 9 immediately after the formation of the wiring 8 on the upper surface of the base body can be omitted.

The shape of the via hole 11 formed in these via hole forming steps can be a perfect circle, ellipse, square, rectangle, etc., but this via hole is formed between the wiring formed on the top surface of the substrate and the wiring on the bottom surface of the substrate. Since the purpose is to form a through hole for electrical conduction, its shape is not particularly important.

Next, a metal thin film layer 12 is formed over the entire lower surface of the substrate while metalizing the exposed side surface of the via hole 11 using a conductive treatment method. The formation of this metal thin film layer 12 is necessary for the subsequent formation of the wiring 15 on the lower surface of the substrate, and its formation can be performed using a dry metal deposition method such as a sputtering method, a vacuum evaporation method, or a wet method such as an electroless plating method. Any metal deposition method can be employed.

(The above figures 2 and 3 (c), jin) and (e),
(See (v)) Step of forming wiring on the lower surface of the substrate: A semi-additive method or a sub-lactic method is used to form the wiring 15 on the lower surface of the substrate.

To form the wiring 15 by a semi-additive method, first, a resist layer 13 is formed on the metal thin film layer 12, and a photomask having a wiring pattern is applied, exposed and developed so that no resist remains on the via hole 11. The resist pattern 14 is formed so that there is no trace.

An example of the photomask is a pattern as shown in FIG. 7, for example.

After forming a wiring section on the lower surface of the substrate by laminating a metal electroplating layer on the exposed portion of the metal thin film layer 12 created by forming the resist pattern 14 as described above, the resist formed by the resist pattern 14 is removed. Then, by melting the metal thin film layer 12 existing thereunder and the metal layer thereunder, it is possible to obtain a base body with wiring 15 formed on the lower surface of the base body.

In order to form the wiring 15 on the lower surface of the base, it is appropriate that the thickness of the metal plating layer formed by electroplating is about 5 to 30 μm.

= 31- When wiring on the lower surface of the substrate is performed by a subtractive method, a metal plating layer is first formed on the metal thin film layer 12 by electroplating. This thickness is similarly 5 to 35
Approximately μm is appropriate.

Next, after forming a resist layer 13 on the metal plating layer, a resist pattern 14 is formed thereon.

Wiring 15 is formed on the lower surface of the substrate by dissolving the exposed portion of the metal plating layer exposed by the formation of resist pattern 14 and the underlying metal layer. The photomask used for forming the wiring on the lower surface of the substrate may have a pattern as shown in FIG. 9, for example.

Note that the resist used in the process of forming wiring on the lower surface of the substrate is the same as that used previously in forming the resist layers 4 and 5, and is used for exposure and development for forming the resist pattern 14, and for metallization. Procedures such as layer dissolution etc. are also the same as those for resist patterns 6 and 7.
It may be carried out in accordance with the procedure followed during formation.

Finally, the organic resin film 9 coated on the top surface of the substrate is removed to complete the double-sided wiring board product.

(See Figure 2 and Figure 3 (e), (e), (e),
(See (F) and (G)) The double-sided wiring board according to the present invention obtained through the above steps is further plated with gold or silver on the exposed metal portion, either entirely or partially, depending on the application. and put it into practical use.

As described above, according to the present invention, wiring is formed on the upper and lower surfaces of the base body based on a predetermined design, and the upper and lower surfaces are formed by forming via holes in the insulating resin, by utilizing various means depending on the situation in each process. Through holes for wiring can be reliably formed.

(Example) Next, examples of the present invention will be described.

In the examples, the steps of forming wiring on the top surface of the substrate, forming via holes, and forming wiring on the bottom surface of the substrate were performed comprehensively by changing various methods, and these were carried out comprehensively by using the symbols shown below to indicate each example number. The steps are shown next to each other in order of process.

Formation of upper surface wiring A: Semi-additive method B Two-layer fabrication method Via hole formation A; Etching method B; Semi-additive method C; Combined method Formation of lower surface wiring A: Semi-additive method B: Sub-I
Herakutiib method Example 1 (A・A・A) Copper sulfate 10g/1) was applied to both sides of a polyimide resin film-like substrate (manufactured by Toshi DuPont, Caputo 7200, thickness 50μm) with a size of 15c + u x 15cm.
, EDTA 60g/, (!, Volf 9f 6me/L dipyridyl 30/ρ, Polyethylene glycol 1 0.5g/
pH 12 using an electroless copper plating solution having a composition of fJ
, 5 was immersed at 70°C for 10 minutes to form an electroless copper plating film, and then immersed in 100% copper sulfate.
Electrolysis is performed at a current density of 2 A/dm2 using an electrolytic copper plating solution having a composition of g/, Q, sulfuric acid 180 g/, 1) to form a base metal layer of copper with a top surface thickness of 1 μm and a bottom surface thickness of 2 μm. I let it happen.

Next, PHER, HC600 (manufactured by Tokyo Ohka Co., Ltd., negative photoresist 1-) was used as a photosensitive resist on the underlying metal layer on the upper surface of the substrate to a thickness of about 40 μm, and also on the underlying copper layer on the lower surface. A similar resist was applied to a thickness of approximately 5 μm using a barter, and each
After drying at 0°C for 30 minutes, the upper register 21
-A glass mask was formed by arranging a wiring pattern of 50 mm x 50 mm in size, a wiring pitch of 200 μm, a wiring width of 100 μm, and 200 wires in a cross-shaped pattern.The first mask was brought into close contact with the resist surface. , 900 mJ of ultraviolet rays were irradiated through the photomask, and a photomask made of glass and having 100 via holes corresponding to the wiring pattern on the upper surface was attached to the lower resist layer, and the photomask had the same size as the upper surface. 1 through the photomask.
Exposure was performed by irradiating 00 mJ of ultraviolet light.

Note that an ultra-high pressure mercury lamp (manufactured by Oak Seisakusho Co., Ltd.) was used for ultraviolet irradiation.

Next, P as a developer is applied to the resist layers on both sides after exposure.
The upper surface was heated to 25°C using HER developer (manufactured by Tokyo Ohka Co., Ltd.).
After developing for 7 minutes at 25° C. on the lower side and 2 minutes at 25° C., each was subjected to drying treatment at 110° C. for 30 minutes to form a predetermined resist pattern.

Next, on the lower side, use 200 g of copper chloride and 50 g of Q solution.
The exposed underlying copper layer was dissolved by dipping at °C for 3 minutes, while the upper surface was electrolyzed for 50 minutes at a current density of 2 A/dm2 using the electrolytic copper plating solution mentioned above.
A wiring part shape was formed as a copper layer having a thickness of 35 μm.

Thereafter, the substrate was treated with a 4% solution of hydroxide I and lium at 50°C for 1 minute to remove the resist on both sides, and the underlying copper layer on the upper surface was coated with copper chloride 100 g/Q, ammonium chloride 100 g/ρ. , ammonium carbonate 110g/Ω, Q and ammonia water 400+J/Ω to form each wiring in an electrically independent state by dissolving it in an ammonia-based alkaline solution, and then using FSR (Fuji) as an organic resin film forming agent. (manufactured by Yakuhin Co., Ltd.) to a thickness of about 10 μm over the entire upper surface of the substrate, and heat-treated at 130'C for 30 minutes to coat the organic resin film.

-36= Next, the substrate was heated to 40°C at 50°C using a solution containing 1:1 ethylalyl and 1N potassium hydroxide mixed in a volume ratio of 1:1.
By dipping for a minute, the exposed portion of the polyimide resin on the bottom surface of the substrate was dissolved and a predetermined via hole was formed on the bottom surface.

Next, after forming a copper thin film layer on the entire lower surface using the electroless copper plating solution mentioned above, P)iER, HC as a photosensitive resist
600 was applied to a thickness of approximately 20 μm using a barter, and after drying at 70°C for 30 minutes, the wiring pitch was 20.
0 μm, a wiring width of 100 μm, and a wiring pattern of 100 wires, each wire was formed so as to be perpendicular to the upper surface wire, and was brought into close contact with the resist surface using a photomask, and 400 mJ was applied through the photomask. After exposure by irradiation with ultraviolet rays, the resist is treated with the developer described above at 25°C for 3 minutes, and then dried at 110°C for 30 minutes to obtain a predetermined resist pattern.

Next, using the electrolytic copper plating solution described above, a current density of 2 A/d was applied.
After electrolyzing at m2 for 25 minutes to form a 18 μm bottom wiring shape on the copper thin film layer exposed on the bottom surface, the remaining resist was soaked in a 4% sodium hydroxide solution for 50'
C for 1 minute to remove it, and then add 200 g of copper chloride/
, Q solution at 50° C. for 3 minutes to dissolve and remove the copper layer on the lower surface of the substrate, thereby forming each wiring on the lower surface in an electrically independent state.

Finally, the organic resin film applied to the top surface of the substrate was removed using FSR stripping solution (manufactured by Fuji Yakuhin Co., Ltd.) as a resin stripping agent at 70°C for 15 minutes.
It is not possible to obtain a double-sided wiring board that has predetermined wiring on the upper and lower surfaces of the substrate and conducts the upper and lower wiring through via holes by peeling and removing the substrate by performing a treatment for 1 minute.

Example 2 (A・A・A) The same polyimide resin film as in Example 1 was used as the starting material, and both sides were coated with 0.00% by sputtering method.
A copper layer with a thickness of 25 μm was formed, and the upper surface thickness was adjusted to 1 μm and the lower surface thickness to 2 μm by electrolytic copper plating, and each treatment was performed in the same manner as in Example]. As a result, a double-sided wiring board similar to Example]- could be obtained.

Example 3 (A・A・B) Using the same polyimide resin film as in Example 1 as a starting material, the steps from forming the base copper layer on both sides of the substrate to forming the copper thin film layer on the bottom surface of the substrate were described in this example. Ko =
The same procedure was followed.

Thereafter, electrolytic treatment was performed for 25 minutes at a current density of 2 A/dm2 using the same electroplating solution as in Example 1 to form a copper layer of approximately 20 μm on the entire lower surface.

PHER・11c was applied as a photosensitive resist on this copper layer.
After applying Boo to a thickness of about 5 μm using a barter and drying, the resist layer thus obtained has a wiring pattern that is inverted from the first mask used in Example 1. After applying a photomask and exposing it to 200 mJ of ultraviolet light through the photomask,
A predetermined resist pattern was obtained by performing development and drying treatment in the same manner as in Example 1.

Next, the exposed copper layer on the bottom surface was dissolved by treatment at 50° C. for 15 minutes using the same copper chloride solution as in [Example] = 39
- Wiring on the lower surface was formed, and then the remaining resist was removed using the same resist removal solution as in Example 1.

Finally, the organic resin film applied to the top surface is peeled off and removed in the same manner as in Example 1 to obtain a double-sided wiring board that has predetermined wiring on the upper and lower surfaces of the substrate and conducts the upper and lower wiring through via holes. I was able to do that.

Example 4 (A・A・B) The same polyimide resin film as in Example C was used as the starting material, and both sides of the film were coated with 0.0% by sputtering method.
The same procedure as in Example 3 was carried out using a substrate on which a copper layer with a thickness of 25 μm was formed, and the thickness of the upper copper layer was adjusted to 1 μm and the thickness of the lower surface copper layer was adjusted to 1 μm and 2 μm, respectively, by electrolytic copper plating. A double-sided wiring board similar to that of Example 3 could be obtained by carrying out each step.

Example 5 fA・B・A) Using the same polyimide resin film as in Example 1 as a starting material, a copper film of approximately 0.2 μm was formed on both sides of the substrate by electroless plating according to the same procedure as in Example 1. After that, electrolysis was carried out at a current density of 2 A/dm2 using the same electrolytic copper plating solution as in [Example]- to form a layer with a thickness of 1 μm on the top surface.
A base copper layer was formed.

Next, PHER・I]c 600 was used as a photosensitive resist on the underlying copper layer on the upper surface of the substrate, and was applied to a thickness of about 40 μm using a barter, and the above-mentioned photoresist was applied on the underlying copper layer on the lower surface. The resist was applied to a thickness of about 5 μm in the same manner as above, and after heating and drying at 70°C for 30 minutes, a photomask having a wiring pattern similar to that used in Example 1 was applied to the upper resist layer on the resist surface. 900 mJ of ultraviolet rays was irradiated through the photomask, and a photomask having an inverted pattern of the via hole pattern used in Example 1 was brought into close contact with the resist surface, and the photomask was Exposure was performed by irradiating 200 mJ of ultraviolet rays through the film.

Next, the resists on both sides were developed and dried at 110'C for 30 minutes to obtain a predetermined resist pattern.

= A 1 − Next, on the upper surface side, a wiring shape having a thickness of about 35 μm was formed by electrolytic copper plating similar to that described above.

On the other hand, the thickness of the lower surface copper layer was adjusted to about 3 μm by electrolyzing the lower surface side using the electrolytic copper plating solution described above at a current density of 2 A/dm 2 for 13 minutes.

After that, the residual resist on both sides was removed, and the base steel layer on the top surface was dissolved with the same ammonia-based alkaline solution as in Example 1 to make each wiring independent, and then an organic resin film was applied over the entire top surface of the substrate by FSR. coated with.

The lower surface side was treated with the same chlorinated steel solution as in Example 1 at 50° C. for 30 seconds to dissolve and remove the underlying copper layer existing between the resist patterns and expose the polyimide resin. The subsequent steps, that is, the formation of via holes in the polyimide resin, the formation of wiring on the bottom surface of the substrate, and the peeling and removal of the organic resin film on the top surface of the substrate, were performed in the same manner as in Example 1, and the predetermined wiring was formed on the upper and lower surfaces. Moreover, it was possible to obtain a double-sided wiring board in which the wiring on the upper and lower surfaces were electrically connected through via holes.

Example 6 (A・B・A) Using the same polyimide resin film as in Example 1 as the starting material, both sides of the film were coated with 0.00% by sputtering method.
Using a substrate on which a copper layer with a thickness of 25 μm was formed and the thickness of the copper layer on the upper surface was adjusted to 1 μm by electrolytic copper plating, each treatment was performed in the same manner as in Example 5. It is not possible to obtain a double-sided wiring board similar to

Example 7 (A-B・B) Using the same polyimide resin film as in Example 1 as the starting material, the steps from forming copper layers on both sides of the substrate to forming predetermined via poles on the lower surface of the substrate were carried out in the same manner as in Example 5. After performing the above steps, the steps from forming a copper thin film layer on the lower surface of the substrate to peeling off the organic resin film on the upper surface of the substrate were carried out in the same manner as in Example 3, thereby forming the prescribed wiring on the upper and lower surfaces of the substrate. However, it is not possible to obtain a double-sided wiring board in which the upper and lower wirings are electrically connected by via poles.

Example 8 (A-B・B) = 43- Using the same polyimide resin film as in Example 1 as the starting material, both sides were coated with 0.000000000000000000000000000 yen by sputtering method, respectively.
Using a substrate on which a copper layer with a thickness of 25 μm was formed and the thickness of the copper layer on the upper surface was adjusted to 1 μm by electrolytic copper plating, each treatment was performed in the same manner as in Example 7. A double-sided wiring board similar to that was obtained.

Example 9 (A・C・A) Using the same polyimide resin film as in Example 1 as a starting material, a copper film of approximately 0.2 μm was formed on both sides of the substrate by electroless copper plating in the same manner as in Example 1. Thereafter, a base copper layer having a thickness of -μm was formed on the upper surface by electrolytic copper plating in the same manner as in Example 1.

Next, PMER-HC600 was applied as a photosensitive resist to a thickness of about 40 μm on the underlying copper layer formed on the upper surface using a barter, and a resist was applied in the same manner on the underlying copper layer on the lower surface. After drying, a photomask having a wiring pattern similar to that used in Example 1 was brought into close contact with the resist surface, and a photomask was applied to the upper resist layer to a thickness of about 5 μm. A photomask having a via hole pattern similar to that used in Example 1 was attached to the lower resist layer, and 200 mJ was irradiated through the photomask.
Exposure was performed by irradiating with ultraviolet light.

Next, the resists on both sides were developed and then dried to form a predetermined wiring pattern on both sides.

Next, the lower surface side was treated with the same copper chloride solution as in Example 1.
A 1-minute treatment at 0 DEG C. dissolved the exposed underlying copper layer, while the top side was electrolytically plated as described above to form a pre-wiring feature approximately 35 .mu.m thick.

Thereafter, the resists on both sides were dissolved, and the underlying copper layer on the top surface was dissolved in the same ammonia-based alkaline solution as in Example 1 to make each wiring independent, and then the entire top surface of the substrate was covered with an organic resin film. .

, ・Next, electrolysis was performed for 3 minutes at a current density of 2A, /d...2 using the electrolytic copper plating solution mentioned above over the entire lower surface,
The thickness of the underlying copper layer pattern on the lower surface of the substrate was 3 μm.

-A'', - After that, from the formation of a predetermined via hole on the lower surface of the substrate,
The steps up to peeling and removal of the organic resin film applied to the upper surface of the substrate are carried out in the same manner as in Example 1 to obtain a double-sided wiring board having predetermined wiring on the upper and lower surfaces and in which the upper and lower wirings are electrically connected by via poles. I was able to do that.

Example 10 (A・C・A) Using the same polyimide resin film as in Example 1 as the starting material, 0 and 0 were applied to both sides of the film by sputtering, respectively.
Using a substrate on which a copper layer with a thickness of 25 μm was formed and the thickness of the copper layer on the top surface adjusted to 1 μm by electrolytic copper plating, each treatment was performed in the same manner as in Example 1, and the results were the same as in Example 1. We were able to obtain a double-sided wiring board.

Example 11 (A/C-B) Using the same polyimide resin Lylum as in Example 1 as a starting material, the steps from forming a copper layer on both sides of the substrate to forming a predetermined via hole on the bottom surface of the substrate will be described as an example. The same procedure was followed, and the subsequent steps from forming a copper thin film layer on the bottom surface of the substrate to peeling off the organic resin film applied to the top surface of the substrate were performed in the same manner as in Example 3. It is not possible to obtain a double-sided wiring board that has a predetermined wiring on the lower surface and conducts the upper and lower wiring through via holes.

Example 12 (A, C, B) Using the same polyimide resin film as in Example 1 as the starting material, both sides of the film were coated with 0.00% by sputtering method.
Each treatment was performed in the same manner as in Example 11 using a substrate on which a copper layer with a thickness of 25 μm was formed and the thickness of the copper layer on the upper surface was adjusted to 18 μm by electrolytic copper plating.
A double-sided wiring board similar to that of Example 11 could be obtained.

Example 13 (B・A・A) After forming the same polyimide resin film as in Example 1 as a starting material, electrolysis was further performed using the same electrolytic copper plating solution as in Example 1, and a thickness was formed on the upper surface. A 35 μm thick copper layer was formed on the lower surface, and a 2 μm thick base copper layer was formed on the lower surface.

Next, PMER HC600 was applied as a photosensitive resist on the copper layer on the upper and lower surfaces using a bar tarter to a thickness of about 5 μm, and after drying at 70°C for 30 minutes, the resist layer on the upper surface was coated with the example A photomask having a wiring pattern inverted from that used in Example 1 was brought into close contact with the resist surface, and 200 mJ of ultraviolet light was irradiated through the photomask. A photomask having a via hole pattern similar to that used in the test was placed in close contact with the photomask, and 200 mJ of ultraviolet rays were irradiated through the photomask to perform exposure.

Next, remove the resist l~ on both sides using P) IER developer.
After developing at 110° C. for 3 minutes, drying treatment was performed at 110° C. for 30 minutes to obtain a predetermined resist pattern.

Next, on the lower side, use the same copper chloride solution as in Example 1.
(Immersion treatment was performed at 5oC for 3 minutes to dissolve the copper in the exposed area, while the upper surface was immersed for 50 minutes in the same copper chloride solution.
By soaking for 20 minutes at
A 5 μm wiring was formed.

Thereafter, the substrate was treated in a 4% sodium hydroxide solution at 50°C for 1 minute to remove the resist on both sides, and then a coating of about 10 μm was applied over the entire upper surface of the substrate using FR3 as an organic resin film. Apply to a thickness of 30 to 130'C.
It was coated by heating and drying for a minute.

Next, the process from forming a via hole on the bottom surface of the substrate to peeling and removing the organic resin film applied to the top surface of the substrate is described as an example],
By following the same procedure as above, it was possible to obtain a double-sided wiring board having predetermined wiring on the upper and lower surfaces of the substrate and having the upper and lower wirings electrically connected through via holes.

Example 14 (B・A・A) Using the same polyimide resin film as in Example] as the starting material, 0 was applied to both sides of the film by sputtering.
．． Example 1 was carried out using a substrate on which a copper layer with a thickness of 25 μm was formed, and the thickness of the copper layer on the upper surface was adjusted to 35 μm by electroplating, and the thickness of the underlying copper layer on the lower surface was adjusted to 2 μm.
When each process was performed in the same manner as in Example 13,
A double-sided wiring board similar to that was obtained.

Example 15 (B・A・B) Using the same polyimide resin film as in Example 1 as a starting material, the steps from forming a copper layer on both sides of the substrate to forming a predetermined via hole on the bottom surface of the substrate were carried out in Example 13. The same procedure was followed.

Subsequently, the steps from forming a copper thin film layer on the bottom surface of the substrate to peeling off the organic resin film applied to the top surface of the substrate were carried out in the same manner as in Example 3, thereby forming predetermined wiring on the top and bottom surfaces of the substrate. However, it is not possible to obtain a double-sided wiring board in which the wiring on the upper and lower surfaces is electrically connected by via poles.

Example 16 (B・A・B) Using the same polyimide resin film as in Example] as the starting material, 0 was applied to both sides of the film by sputtering.
, a copper layer with a thickness of 25 μm was formed, and the thickness of the copper layer on the upper surface was adjusted to 35 μm on the upper surface and the thickness of the underlying copper layer on the lower surface was adjusted to 2 μm by electrolytic copper plating.
When each process was performed in the same manner as in Example 15,
A double-sided wiring board similar to that was obtained.

Example 17 (B・B・A) Using the same polyimide resin film as in Example] as a starting material, a film of about 0.2 μm was applied to both sides of the substrate by electroless plating in the same manner as in Example]. After forming the copper film, electrolytic copper plating was performed in the same manner as in Example 1 to make the thickness of the copper layer on the upper surface of the substrate 35 μm.

Next, P14ER/HC600 is applied as a photosensitive resist to a thickness of about 5 μm on the copper layer on the upper and lower surfaces, and after drying, the resist layer on the upper surface has a wiring pattern similar to that used in Example 13. A photo mask was brought into close contact with the resist surface, and 200 mJ was applied through the photomask.
A photomask having a via hole pattern similar to that used in Example 5 was placed on the lower resist layer in close contact with the resist I surface, and 200 mJ of ultraviolet rays was irradiated through the photomask. Exposure was carried out by doing this.

Next, the resists I~ on both sides were developed in the same manner as in the example, and then dried to obtain a predetermined resist pattern.

Next, on the upper surface side, a wiring having a thickness of about 35 μm was formed using a copper chloride solution in the same manner as in Example 13.

On the other hand, the lower surface side was plated with a current density of 2 using the electroplating solution mentioned above.
Electrolyze at A/dm2 for 13 minutes to reduce the thickness of the bottom copper layer to about 3
Adjusted to μm. After that, remove the resist on both sides,
Next, the entire upper surface of the substrate was coated with an organic resin film using FSR.

Subsequently, the steps from exposing the polyimide resin by dissolving the copper layer on the bottom surface of the substrate to peeling off the organic resin film applied to the top surface of the substrate were performed in the same manner as in Example 5, and a predetermined wiring was formed on the top and bottom surfaces of the substrate. However, it is not possible to obtain a double-sided wiring board in which the upper and lower wirings are electrically connected through via holes.

Example 18 (B・B・A) The same polyimide resin foam as in Example 1 was used as the starting material! A copper layer with a thickness of 0.25 μm was formed on both sides by sputtering, and the thickness of the copper layer on the top surface was adjusted to 35 μm by electrolytic copper plating. When each treatment was carried out in the same order as in Example 17, a double-sided wiring board similar to that in Example 17 could be obtained.

Example 19 (B-B・B) Using the same polyimide resin film as in Example 1 as a starting material, the steps from forming a copper layer on both sides of the substrate to forming an organic resin film on the upper surface of the substrate were performed as in Example 17. By following the same procedure as in Example 7 and subsequently performing the steps from exposing the polyimide resin by dissolving the underlying copper layer on the bottom surface of the substrate to peeling off and removing the organic resin applied to the top surface of the substrate, the substrate was It is not possible to obtain a double-sided wiring board that has predetermined wiring on the top and bottom surfaces and is electrically connected by wiring or via holes on the two bottom surfaces.

Example 20 (B-B・B) Using the same polyimide resin film as in Example]- as a starting material, a 0.0 lb.
．． Using a substrate on which a copper layer with a thickness of 25 μm was formed and the thickness of the copper layer on the upper surface was adjusted to 35 μm by electrolytic copper plating, each treatment was performed in the same manner as in Example 19. It is not possible to obtain a double-sided wiring board similar to

Example 21 (B, C, A) Using the same polyimide resin film as in Example 1 as a starting material, Example 1. A copper layer of about 20 μm was formed using the same electroless plating solution as in Example 1, and the thickness of the copper layer on the top surface was made 35 μm using the same electrolytic copper plating solution as in Example 1.

Next, PHER HC40 was applied as a photosensitive resist to a thickness of about 5 μm on the copper layer on the upper and lower surfaces.
After drying, the upper resist layer was coated with Example 1.
A photomask having a wiring pattern similar to that used in Example 3 was brought into close contact with the resist surface, and 200 mJ of ultraviolet light was irradiated through the photomask, and the resist layer on the lower surface was coated with the same pattern as that used in Example 1. A photomask having a similar via hole pattern was brought into close contact with the resist surface, and exposure was performed by irradiating ultraviolet rays of 20011 m through the photo mask.

Next, after developing the resist on both sides, a drying process was performed to obtain a predetermined wiring pattern.

Then, the lower surface side was treated with the same chlorinated steel solution as in Example 1 at 50 °C for 1 minute to dissolve the exposed copper layer, while the upper surface side was dissolved using the same copper chloride solution. Then, the exposed copper layer was melted to form a wiring having a thickness of 35 μm. Thereafter, the resin on both sides was dissolved in Resis 1, and then the entire upper surface of the substrate was covered with an organic resin film by FSR.

Subsequently, the steps from adjusting the thickness of the base copper layer by electrolytic copper plating on the bottom surface of the substrate to peeling off and removing the organic resin film applied to the top surface of the substrate are carried out in the same manner as in Example 1, thereby forming a predetermined pattern on the top and bottom surfaces of the substrate. It is not possible to obtain a double-sided wiring board that has wiring on the bottom surface and conducts the wiring on the lower surface through via holes.

Example 22 (B, C, A) The same polyimide resin film as in Example 1 was used as the starting material, and both sides of the film were coated with 0.00% by sputtering method.
An example using a substrate in which a copper layer with a thickness of 25 μm was formed and the thickness of the copper layer on the upper surface was adjusted to 35 μm by electrical steel plating? When each process was carried out in the same manner as in Example 1, it was not possible to obtain a double-sided 55-sided wiring board similar to that in Example 21.

Example 23 (B, C, B) Using the same polyimide resin film as in Example 1- as a starting material, the steps from forming a copper layer on both sides of the substrate to coating the top surface of the substrate with an organic resin film were carried out in Example 21. By carrying out the same procedure as in Example 9, the subsequent steps from exposing the polyimide resin by dissolving the underlying copper layer on the lower surface of the substrate to peeling off and removing the organic resin applied to the upper surface of the substrate were carried out in the same manner as in Example 9. It was possible to obtain a double-sided wiring board that had predetermined wiring on the upper and lower surfaces of the base and in which the wiring on the upper and lower surfaces were electrically connected through via holes.

Example? 4 (B/C1B) Using the same polyimide resin film as the actual probe as a starting material, a copper layer with a thickness of 0.25 μm was formed on each side by this sputtering method, and each treatment was applied in sequence. As a result, a double-sided wiring board similar to that of Example 23 could be obtained.

(Effects of the Invention) As described above, when using the method for manufacturing a double-sided wiring board of the present invention, the substrate is formed by forming a metal layer such as a copper layer on both sides of an insulating resin film without using an adhesive. A double-sided wiring board in which prescribed wiring is reliably formed on the upper and lower surfaces of the insulating resin without impairing its original performance, and the wiring formed on the upper and lower surfaces is electrically connected through via holes formed in the insulating resin. This can be said to be an invention far superior to that of I-music.

[Brief explanation of drawings]

FIG. 1 is a step-by-step process diagram showing the manufacturing process of the double-sided wiring board manufacturing method of the present invention, and FIGS. 2(a) and (b)
Figures 3(a) and 3(b) show the schematic state of the substrate in the manufacturing process of a double-sided wiring board when the semi-additive method and subtractive method are used for wiring on the top surface of the substrate, respectively. g) Explanatory drawings shown in order; FIG. 4 is a plan view showing the appearance of an example of a double-sided wiring diagram obtained by implementing the present invention; FIG. 6 and 7 are plan views illustrating a photomask having a via hole pattern formed on the bottom surface of a substrate, respectively. FIGS. FIG. 3 is a plan view showing a photomask having a predetermined wiring pattern applied thereto. DESCRIPTION OF SYMBOLS 1...Top metal layer, 2...Bottom metal layer, 3...Insulating resin base, /1. ．． 5, 13... Regis I-layer,
6.7.1!1...Resist pattern, 8...''-
Surface wiring, 9... Organic resin film, 10... Metal layer pattern, 11... Via hole, 12... Metal thin film layer, 1
5... Bottom wiring. Patent applicant: Sumitomo Metal Mining Co., Ltd. ・1 Figure 1 Double-sided circuit board manufacturing process diagram Insulating resin base Metal layer/resist pattern formation Formation of semi-wiring (top surface) Additive method Practical method Touching method Medial additive method Usage Mere additive method Buttractive method Figure 5 Figure 6 Figure 7 Figure 8

Claims (9)

[Claims] (1) The base is an insulating resin film with metal layers formed on both sides without using an adhesive, and after forming a photosensitive resist layer on the metal layers on both sides of the base, the resist layer on the top surface of the base is A photomask mainly having a predetermined wiring pattern is applied, and a photomask mainly having a predetermined via hole pattern is applied to the resist layer on the lower surface of the substrate, and after irradiation with light, the resist layers on both sides are developed, and the resist layers on both sides of the substrate are coated. The process of forming a resist pattern of each shape, the process of forming wiring on the top surface of the substrate by performing wiring formation processing according to the resist pattern formed on the top surface of the substrate, and the process of forming wiring on the bottom surface of the substrate according to the resist pattern formed on the bottom surface of the substrate. After melting the metal layer in the part to be exposed to expose the insulating resin, melting the exposed part of the insulating resin to form a predetermined via hole, and forming a metal thin film layer on the bottom surface of the substrate after forming the via hole. After that, a photosensitive resist layer is again formed on the metal thin film layer, a photomask having a predetermined wiring pattern is applied on the resist layer, irradiated with light, and then developed to form a resist pattern on the lower surface of the substrate, A method for manufacturing a double-sided wiring board, comprising the step of forming a predetermined wiring by performing a wiring formation process on the lower surface of the substrate according to the resist pattern. (2) The wiring on the top surface of the substrate is formed by laminating a metal plating layer by electroplating on the exposed metal layer according to the resist pattern formed on the top surface of the substrate to form a pre-wiring shape, and then applying the resist on the top surface of the substrate and the bottom of the resist. 2. The method for manufacturing a double-sided wiring board according to claim 1, wherein the method is carried out by dissolving and removing a metal layer present in the double-sided wiring board. (3) The double-sided wiring board according to claim 1, wherein the wiring on the upper surface of the substrate is formed by etching the exposed metal layer according to a resist pattern formed on the upper surface of the substrate, and then dissolving and removing the resist on the non-etched metal layer. Production method. (4) To form a predetermined via hole in the insulating resin substrate, the exposed metal layer is etched according to the resist pattern formed on the bottom surface of the substrate to expose the insulating resin portion, and then the resist on the bottom surface of the substrate is removed. 4. The method for manufacturing a double-sided wiring board according to claim 1, wherein the method is carried out by dissolving and removing exposed portions of the insulating resin. (5) To form a predetermined via hole in an insulating resin substrate, a metal plating layer is laminated by electroplating on the exposed metal layer according to the resist pattern formed on the bottom surface of the substrate to form a metal pattern, and then a metal plating layer is formed on the resist and under the resist. Claim 1: The method is carried out by dissolving and removing the existing metal layer and thereby dissolving and removing the exposed insulating resin.
4. The method for manufacturing a double-sided wiring board according to any one of 3 to 3. (6) To form a predetermined via hole in the insulating resin substrate, the exposed metal layer is etched according to the resist pattern formed on the bottom surface of the substrate to expose the insulating resin part, and then the resist pattern on the bottom surface of the substrate is removed. The method for manufacturing a double-sided wiring board according to any one of claims 1 to 3, wherein a metal plating layer is laminated by electroplating on the metal layer exposed by the above process, and the exposed portion of the insulating resin is dissolved and removed. (7) To form wiring on the bottom surface of the substrate, a metal plating layer is deposited by electroplating on the exposed metal thin film layer according to the resist pattern formed again on the bottom surface of the substrate, then the resist is dissolved and removed, and the metal layer existing under the resist is 7. The method for manufacturing a double-sided wiring board according to claim 1, wherein the method is carried out by dissolving and removing the thin film layer and the metal layer existing thereunder. (8) The wiring on the bottom surface of the substrate is formed by laminating a metal plating layer by electroplating on the metal thin film layer on the bottom surface of the substrate, and then following the resist pattern formed again on the bottom surface of the substrate, the exposed metal plating layer and the metal plating layer below it are formed. 7. The method for manufacturing a double-sided wiring board according to claim 1, wherein the method for manufacturing a double-sided wiring board is carried out by dissolving and removing the metal thin film layer and the metal layer existing thereunder. (9) The double-sided wiring board according to any one of claims 1 to 8, wherein the entire upper surface of the substrate is coated with an organic resin film layer from the time the wiring is formed on the upper surface of the substrate until the completion of the formation of the wiring on the lower surface of the substrate. Production method.