JP2000357857A - Manufacture of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of manufacturing a printed wiring board of high reliability wherein higher density packaging is enabled with high yield, by using a simple process. SOLUTION: This manufacturing method is composed of a process wherein selective maskings 2a, 2b are performed to one surface of a conductive metal foil 1, and a protruding wiring pattern 1a is formed by half etching; a process wherein the masking layer 2a on the surface of the wiring pattern 1a formed in a protruding shape is eliminated, the surface of the wiring pattern 1a is made to face the main surface of an insulating resin layer 3, and lamination and arrangement are performed; a process wherein the laminated member is pressed, the protruding wiring pattern 1a is buried in the insulating resin layer 3, and these are collectively formed in an unified body; and a process wherein the conductive metal foil 1 is eliminated by etching, leaving a wiring pattern 1a' which is buried in the insulating member layer 3, and the wiring pattern 1a' is exposed on the surface of the insulating resin layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a method for manufacturing a printed wiring board having a structure in which wiring layers are connected by a penetrating conductor and capable of high-density mounting. .

[0002]

2. Description of the Related Art In a double-sided printed wiring board or a multilayer printed wiring board, electrical connection between wiring layers such as double-sided conductive patterns is performed as follows. For example,
In the case of a double-sided printed wiring board, first, a predetermined position of the double-sided copper foil-clad board is subjected to drilling, and the entire surface including the inner wall surface of the drilled hole is subjected to chemical plating, and then electroplating is performed. Processing is performed to increase the reliability by increasing the thickness of the metal layer, and electrical connection between wiring layers is performed.

In the case of a multilayer printed wiring board, a copper foil stretched on both sides of a substrate is patterned by wiring, and then the copper foil is laminated and arranged on the wiring patterning surface via an insulating sheet (for example, a prepreg). After applying heat and pressure to integrate, as in the case of the above-mentioned double-sided printed wiring board, multi-layer printing by electrical connection between wiring layers by drilling and plating and wiring patterning of surface copper foil I have a wiring board. In the case of a multilayer printed wiring board having more wiring layers, it can be manufactured by a method of increasing the number of double-sided printed wiring boards interposed in the middle.

On the other hand, a method of manufacturing a printed wiring board with a simplified manufacturing process has been developed. For example, a conductor bump (conductive protrusion) for interlayer conduction is formed at a predetermined position on the surface of the first conductive metal layer, and a synthetic resin sheet having heat melting property is formed on the conductor bump formation surface. A second conductive metal layer is stacked and arranged. Next, the laminate is pressed to penetrate the tip of the conductor bump in the thickness direction of the synthetic resin-based sheet, and is electrically connected to the opposing second conductive metal layer surface.

[0005] Thereafter, the first and second conductive metal layers are subjected to photo-etching to pattern the wiring. Based on such a process, a method of manufacturing a double-sided wiring board or a multilayer wiring board that enables high-density wiring while reducing complicated steps such as interlayer connection has been put to practical use.

[0006]

The means for electrically connecting the wiring layers with the conductive protrusions (conductor bumps) having the interlayer insulating layer (synthetic resin-based sheet) penetrated in the thickness direction is described above. Compared with the method of manufacturing a printed wiring board using a plating method, it is possible to omit the drilling process, the plating process including the inner wall surface of the hole, etc. (shortening of the manufacturing process), and to greatly reduce the complexity of the process management. However, on the other hand, the following problems have been observed in the manufactured printed wiring boards, and in practical use,
In addition, it cannot be said that the state is sufficiently satisfactory.

For example, a thin printed wiring board in which a fine wiring pattern having a line width of about 30 to 100 μm is provided on an insulator layer (support) surface having a thickness of about 100 μm, the bending of the wiring pattern causes The portion may peel off from the insulator layer. That is, when the wiring pattern is miniaturized, the bonding surface of the wiring pattern to the insulator layer is small, and
Since it protrudes from the insulator layer surface, when an external force such as bending or pulling is applied, the integrity with the insulator layer surface is impaired, and there is a disadvantage that peeling is likely to occur. Further, there is also a problem that the wiring pitch of the wiring pattern is restricted, and high-density wiring is impaired. That is, the wiring patterns protrude and are arranged on the surface of the insulator layer, and the adjacent wiring patterns are not necessarily insulated or separated from each other. Therefore, for example, when mounting electronic components, adjacent wiring patterns are soldered. There is a risk of short-circuiting between patterns. Therefore, a wiring pitch that takes into account safety is taken into account, and the wiring density is restricted, and further, the miniaturization of the printed wiring board is also restricted. As a result, the reliability, miniaturization, and product yield of the circuit device using the printed wiring board are greatly affected, and thus a serious problem is raised in practical use.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a method capable of mounting a highly reliable printed wiring board with a high yield by a simple process with a high yield. And

[0009]

According to a first aspect of the present invention, there is provided a method for selectively masking one main surface of a conductive metal foil and half-etching to form a convex wiring pattern; Removing the masking layer on the wiring pattern surface formed in a shape, stacking and disposing the wiring pattern surface facing the main surface of the insulating resin layer, and insulating the convex wiring pattern by pressing the laminate. Embedded in a conductive resin layer, and a step of etching and removing the conductive metal foil while leaving the wiring pattern embedded in the insulator layer to expose the wiring pattern to the insulating resin layer surface. This is a method for manufacturing a printed wiring board. This claim 1
In the invention of the first aspect, at least one side of the wiring pattern is formed by embedding a convex wiring pattern formed by half etching, and the height of the convex wiring pattern by half etching (in other words, the height of half Depending on the degree), electrical connection between the wiring patterns on both sides can be made by joining the corresponding projections.

According to a second aspect of the present invention, there is provided a process of selectively masking one main surface of a conductive metal foil and half-etching to form a convex wiring pattern; and forming the convex wiring pattern. Removing the masking layer on the pattern surface and providing conductive protrusions for interlayer conduction at required positions, positioning and laminating and disposing a conductive metal foil with the wiring pattern surface facing the main surface of the insulating resin layer; Step and pressurizing the laminate to embed a convex wiring pattern in the insulating resin layer,
And a step of integrating the conductive metal foil and the insulating resin layer while penetrating the conductive protrusions, and etching away the conductive metal foil while leaving the wiring pattern embedded in the insulator layer to insulate the wiring pattern. Exposing it to the surface of a conductive resin layer.

According to a third aspect of the present invention, there is provided a step of masking one main surface of the first conductive metal foil and half-etching to form a convex wiring pattern; Removing the masking layer on the wiring pattern surface and providing a first conductive protrusion for interlayer conduction at a required position;
Positioning and laminating and arranging the first conductive metal foil with the wiring pattern surface facing the main surface of the first insulating resin layer; and pressing the laminate to form the first wiring pattern into a first wiring pattern. A step of integrating the first conductive metal foil and the first insulating resin layer while embedding in the insulating resin layer and penetrating the first conductive protrusion; and embedding the first insulating layer in the first insulating layer. Removing the first conductive metal foil by etching while leaving the wiring pattern, exposing the wiring pattern to the first insulating resin layer surface; and providing a conductive layer for interlayer conduction at a required position on the exposed wiring pattern surface. A step of providing a projection, and a step of providing a second conductive metal foil, in which a convex wiring pattern is provided by half-etching, on a surface of the first insulating resin layer exposing the wiring pattern, via a second insulating resin layer. Before and after stacking and positioning The laminate is pressed to embed the convex wiring pattern in the second insulating resin layer, and integrate the second conductive metal foil with the second insulating resin layer while penetrating the conductive protrusions. And a step of exposing the wiring pattern to the insulating resin layer surface by etching and removing the second conductive metal foil so as to be flush with the second insulator layer surface. This is a method for manufacturing a wiring board.

According to a fourth aspect of the present invention, there is provided a step of masking one main surface of the first conductive metal foil and half-etching to form a convex wiring pattern, and the step of forming the convex wiring pattern. Removing the masking layer on the wiring pattern surface and providing a first conductive protrusion for interlayer conduction at a required position;
Positioning and laminating and arranging the first conductive metal foil with the wiring pattern surface facing the main surface of the first insulating resin layer; and pressing the laminate to form the first wiring pattern into a first wiring pattern. A step of integrating the first conductive metal foil and the first insulating resin layer while embedding in the insulating resin layer and penetrating the first conductive protrusion; and embedding the first insulator i. Etching the first conductive metal foil while leaving the wiring pattern, exposing the wiring pattern on the first insulating resin layer surface; and forming a convex shape on the first insulating resin layer surface exposing the wiring pattern. Positioning, laminating and arranging, via a second insulating resin layer, a second conductive metal foil in which the wiring pattern of (1) is provided by half-etching and a conductive protrusion for interlayer conduction is provided at a predetermined position; Pressurizing the laminate to form a convex wiring pattern. Embedding the second conductive metal foil on the second insulating resin layer side while embedding the conductive layer in the second insulating resin layer, and penetrating the conductive protrusions; Etching the second conductive metal foil while leaving the wiring pattern embedded in the body layer to expose the wiring pattern on the surface of the insulating resin layer.

In the production of a multilayer printed wiring board, the step of forming conductive protrusions on the outer layer wiring patterning surface according to the third and fourth aspects of the present invention, The step of laminating the conductive resin layer (synthetic resin-based sheet) and another conductive metal foil, the step of applying pressure, and the like may be repeated as appropriate.

In the first to fourth aspects of the present invention, the conductive metal foil may be, for example, an electrolytic copper foil, such as a blackened copper foil having a thickness of about 12 to 70 μm, which is usually used for manufacturing a printed wiring board. Foil, nickel foil and the like.
The patterning of the convex wiring on one main surface side by half etching is performed by so-called photo etching, and the degree of half etching (film thickness to be removed by etching) means strictly about half (about 50%). It means that the initial film thickness is reduced. For example, when the thickness of the conductive metal foil is 18 μm,
m and about 5-20 μm when the thickness is 35 μm.

In this case, the half etching may be performed in multiple stages so that a part of the convex wiring pattern also serves as a conductor for interlayer connection. A metal layer such as nickel may be provided on the wiring pattern surface. Further, the depth of the half etching can be arbitrarily changed and set. That is,
By appropriately setting the half-etching amount (depth), it is possible to miniaturize the wiring or increase the precision of the fineness.

According to the second to fourth aspects of the present invention, the conductive projections (conductor bumps) formed at predetermined positions on the conductive metal foil surface and the outer layer wiring pattern surface are made of, for example, silver, gold, copper, solder powder or the like. Prepared by mixing conductive powder, their alloy powder or composite (mixed) metal powder with binder components such as polycarbonate resin, polysulfone resin, polyester resin, epoxy resin, melamine resin, phenoxy resin, phenol resin and polyimide resin Made of a conductive composition or a conductive metal.
When the conductive projection is formed of a conductive composition, the conductive projection having a high aspect ratio can be formed by, for example, a printing method using a relatively thick metal mask.

On the other hand, means for forming conductive projections of conductive metal include: (a) spraying a fine metal soul having a certain shape or size to a positive pattern surface on which an adhesive layer is provided in advance; Selective fixation or (b) means of applying a plating resist on the positive pattern surface, performing chemical plating by patterning, immersing in a solder bath to selectively form minute metal columns, etc. .

In the case where the conductive projections are formed of a conductive composition, the steps and the like can be further simplified as compared with the case where the conductive projections are formed by means such as a plating method, which is effective in terms of cost reduction.

In the first to fourth aspects of the present invention, the ridge wiring pattern is buried, or the tip of the conductive projection is inserted and press-fitted to form a through-type conductor (electrical connection). Examples of the insulating resin layer include a thermoplastic resin film (sheet) and an epoxy resin-glass cloth system in a semi-cured state. The thickness of the insulating resin layer depends on the height (thickness) of the convex wiring pattern and the conductive property. The thickness is determined by the height of the lip, and is generally preferably about 30 to 100 μm.

Here, examples of the thermoplastic resin sheet include a liquid crystal polymer, a polycarbonate resin, a polysulfone resin, a thermoplastic polyimide resin, a polyetherimide resin, a tetrafluoroethylene resin, a tetrafluoroethylene resin, and a hexafluoropolypropylene resin. And sheets such as polyetheretherketone resin. Further, as a thermosetting resin sheet held in a semi-cured state, epoxy resin, bismaleimide triazine resin, polyimide resin, phenol resin, polyester resin, melamine resin, or butadiene rubber, butyl rubber, natural rubber, neoprene rubber, silicone rubber, etc. Raw rubber sheets.

The synthetic resin sheet may be used alone or may contain an insulating inorganic or organic filler. Further, a reinforcing material such as glass cloth or mat, organic synthetic fiber cloth or mat, or paper may be used. May be combined with the sheet. However, in any case, it is necessary to exhibit heat-fusibility enough to press and press-fit at least a convex wiring pattern while having chemical resistance and mechanical strength enough to withstand patterning processing by etching. is there.

In the first to fourth aspects of the present invention, the etching after the convex wiring pattern is buried in the insulating resin layer is performed so that at least the buried wiring pattern remains insulated and separated from each other. It is necessary that the surface is substantially the same as the surface of the layer, and generally, the surface is slightly lower than the surface of the insulating resin layer (concave surface).

According to the first aspect of the present invention, a fine wiring pattern is formed, and the wiring pattern disposed and exposed in the outer layer is embedded in the insulating resin layer on the other peripheral surface except for one surface,
While being insulated and separated from each other, they are integrated with the insulating resin layer. In other words, a printed wiring board in which adjacent fine wirings ensure reliable insulation while maintaining the bonding and integrity with the insulating resin layer can be obtained while omitting complicated means and the like.

According to the second to fourth aspects of the present invention, a conductor portion (conductor wiring portion) between the wiring patterns for electrically connecting between the wiring pattern layers.
In the process of applying pressure (and, if necessary, heating) in the so-called laminating and integrating process, a highly reliable electrical connection between the wiring layers is ensured by conductive projections penetrating the insulating resin layer. Achieved. On the other hand, the wiring pattern disposed / exposed on the outer layer, except for one surface, is embedded in the insulating resin layer, and is insulated / separated from each other, and is integrated with the insulating resin layer.

That is, even if the wiring pattern is fine, the printed wiring board in which the adjacent wirings ensure reliable insulation while maintaining the joint and the integrity with the insulating resin layer can be provided by complicated means. Is obtained while omitting. here,
The fact that the outer layer wiring pattern forms the same plane (flat surface) as the printed wiring board means that, for example, in the case of soldering, the occurrence of bridges between adjacent connection terminals at a narrow pitch is also avoided. Combined with proper wiring patterning, a highly reliable compact or high-density wiring board can be obtained.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, FIGS. 1 (a) to 1 (e) and 2 (a)
Embodiments will be described with reference to FIGS. 3 (f), 3 (a) to 3 (c), 4 (a) to 4 (b) and FIG.

Embodiment 1 FIGS. 1A to 1E schematically show an embodiment of this embodiment.

First, an electrolytic copper foil having a thickness of 35 μm is prepared, and as shown in a sectional view of FIG. 1A, a required wiring pattern is formed on one main surface of the electrolytic copper foil 1 and on another main surface. Provided photo-etching resist films 2a and 2b on the entire surface. Thereafter, one principal surface of the electrolytic copper foil 1 is half-etched using, for example, an aqueous cupric chloride solution as an etchant, thereby forming a convex wiring pattern 1a as shown in a cross section in FIG. 1 (b). . Next, the resist masks 2a and 2b were peeled off and removed to obtain an electrolytic copper foil 1 having a wiring pattern 1a formed on one side in a convex shape.

Next, the wiring pattern 1a of the electrolytic copper foil 1 will be described.
FIG. 1C is a cross-sectional view showing a liquid crystal polymer sheet (resin insulator layer) 3 having a thickness of 0.1 mm on the forming surface and an electrolytic copper foil 1 ′ having a convex wiring pattern 1 a formed thereon according to the above. As described above, positioning and lamination were performed. Thereafter, the laminate was set between hot plates of a hot press, and was pressed at a temperature equal to or higher than the glass transition of the liquid crystal polymer sheet 3, preferably at a resin pressure of about 2 MPa when in a thermoplastic state.

By this pressure treatment, the convex wiring patterns 1a, 1a 'of the electrolytic copper foil 1' are buried in the thickness direction of the liquid crystal polymer sheet 3 as shown in cross section in FIG. A copper-clad substrate 4 was obtained.

Next, the copper-clad substrate 4 was subjected to an etching treatment using an aqueous cupric chloride solution as an etching solution.
That is, the copper foil 1 'is etched until the surface of the liquid crystal polymer sheet 3 is exposed, and as shown in a sectional view in FIG.
The printed wiring board 6 in which 1a was embedded was obtained.

A conductor portion 3 'formed by a conductor bump 3 into which an epoxy resin-glass cloth prepreg 4 is pressed and inserted.
Thus, the printed wiring board 6 embedded in both sides and connected by 1a 'was obtained.

Embodiment 2 FIGS. 2A to 2F schematically show an embodiment of this embodiment.

First, an electrolytic copper foil having a thickness of 18 μm is prepared, and as shown in a sectional view of FIG. 2A, a required wiring pattern is formed on one main surface of the electrolytic copper foil 1 and on another main surface. Provided photo-etching resist films 2a and 2b on the entire surface. Thereafter, one principal surface of the electrolytic copper foil 1 is half-etched using, for example, a cupric chloride aqueous solution as an etching solution, to form a convex wiring pattern 1a as shown in a cross-section in FIG. 2B. . Next, the resist masks 2a and 2b were peeled off and removed to obtain an electrolytic copper foil 1 having a wiring pattern 1a formed on one side in a convex shape.

A silver-based conductive paste using an epoxy resin as a binder is printed on a predetermined position surface of the convex wiring pattern 1a of the electrolytic copper foil 1 via a metal mask, and the printed conductive paste is dried. Then, as shown in a cross-sectional view in FIG. 2C, a conical conductor pump 6 was formed (formed) on a predetermined position surface of the convex wiring pattern 1a.

Next, an electrolytic copper foil 1 on which the conductor pump 6 was formed, an epoxy resin-glass cloth prepreg (resin insulator layer) 3 having a thickness of 0.1 mm, and a convex wiring pattern 1a 'according to the above were formed. The formed 18μm thick electrolytic copper foil 1 '
Positioning and lamination were performed as shown in cross section in FIG. Thereafter, the laminate is set between hot plates of a hot press, and is heated at a temperature equal to or higher than the glass transition of the epoxy resin-glass cloth prepreg 3, preferably at a resin pressure of about 2 MPa when in a thermoplastic state. Pressed.

By this pressurizing treatment, the tip of the conductor bump 6 is press-fitted in the thickness direction of the synthetic resin sheet 3 as shown in cross section in FIG. A double-sided copper-clad board 7 which is electrically connected to one surface of the foil and in which the convex wiring patterns 1a, 1a 'of the copper foils 1, 1' are embedded
I got In addition, the epoxy resin-glass cloth prepreg 3 is prepared by adding epoxy resin (curing conditions, 175) to the glass cloth.
(At 60 ° C for 60 to 90 minutes) and then heat-treated at 175 ° C for 10 to 20 minutes.

Next, the double-sided copper-clad substrate 7 was subjected to an etching treatment using a cupric chloride aqueous solution as an etching solution. That is, the copper foils 1, 1 'on both sides are
The etching process is performed until the surface is exposed, and as shown in a sectional view in FIG. 2 (f), the conductor portion 6 'formed by the conductor bump 6 into which the epoxy resin-glass cloth prepreg 3 is pressed and inserted is formed. The printed wiring board 8 connected to the wiring patterns 1a and 1a 'embedded on both sides was obtained.

An electric check, which is usually performed, was performed on the double-sided printed wiring board 8 manufactured as described above.
No problems such as defects or reliability were found in all connection parts. In order to evaluate the reliability of the connection between the double-sided wiring putters, a hot oil test (a cycle of immersion in 260 ° C. oil for 10 seconds and immersion in 20 ° C. oil for 20 seconds is one cycle) No failure was observed even after 500 times, and the reliability of connection between the wiring pattern layers was remarkably superior to the conventional method of forming a penetrating conductor by copper plating.

Embodiment 3 FIGS. 3A to 3C schematically show an embodiment of the present embodiment.

First, as shown in cross section in FIG. 3A, a printed wiring board 8 obtained in the same manner as in Example 2 was prepared.
The conductive bumps 6 were provided at predetermined positions of the wiring pattern 1a 'on one main surface of the printed wiring board 8. Next, a copper foil 1 having a separately manufactured convex wiring pattern 1a and provided with conductive bumps 6, a similarly convex wiring pattern
A copper foil 1 'having 1a' and an epoxy resin-glass cloth prepreg 3 were cross-sectionally shown in FIG.
Positioned and stacked.

Thereafter, the laminate is set between hot plates of a hot press via a backing plate, and is set at a temperature equal to or higher than the glass transition of the epoxy resin-glass cloth prepreg 3, preferably in a thermoplastic state. , Pressurize at a resin pressure of about 2 MPa, raise the temperature to 170 ° C in this state, hold for 1 hour,
Removed after cooling. In this step, as shown in cross section in FIG. 3 (c), the tip of the conductor bump 6 is press-fitted in the thickness direction of the synthetic resin sheet 3, and the opposing wiring patterns 1a,
On the 1a 'side, a double-sided copper foil-clad multilayer substrate 9 which was electrically connected to each other was obtained.

Next, the double-sided copper-clad multilayer substrate 9 was subjected to an etching treatment using an aqueous cupric chloride solution as an etching solution. That is, the copper foils 1 and 1 'on both sides are etched until the surface of the synthetic resin sheet 3 is exposed, and the conductor portions 6' to be formed by the conductor bumps 6 into which the epoxy resin-glass cloth prepregs 3 are press-fitted and inserted. Thus, a printed wiring board connected to the wiring patterns 1a, 1a 'embedded on both sides was obtained.

The multilayer printed wiring board was subjected to a usual electrical check. As a result, it was found that all the connection portions were defective or unreliable. In order to evaluate the reliability of the connection between the wiring putters 1a and 1a ', a hot oil test (a cycle of immersion in oil at 260 ° C for 10 seconds and immersion in oil at 20 ° C for 20 seconds is one cycle). ) Was performed 500 times, no failure was observed.

Embodiment 4 FIGS. 4A and 4B schematically show an embodiment of the present embodiment.

As in the case of Example 2, an electrolytic copper foil having a thickness of 18 μm was prepared, and a required wiring pattern was formed on one main surface of the electrolytic copper foil 1, and the other main surface was entirely formed. Each was provided with a photoetching resist film. Thereafter, for example, using a cupric chloride aqueous solution as an etching solution, the one main surface of the electrolytic copper foil 1 is subjected to half-etching treatment in two parts, and as shown in cross section in FIG. Then, the resist mask is peeled off and removed to obtain an electrolytic copper foil 1 having a wiring pattern 1a ″ formed on one surface in a convex shape.

Two electrolytic copper foils 1 are prepared, and the surfaces on which the convex wiring patterns 1a ″ are formed are opposed to each other.
With a 0.1 mm liquid crystal polymer (resin insulator layer) 3 interposed,
Positioning and stacking arrangement. Note that a thin solder layer was provided at the tip of the convex portion of the convex wiring pattern 1a ″. Thereafter, the laminated body was set between hot plates of a hot press, and the softening point of the liquid crystal polymer 3 was changed. At a resin pressure of about 2 MPa.

By this pressure treatment, as shown in a sectional view in FIG.
1a "A double-sided copper-clad substrate 7 'was obtained in which the tip surfaces were electrically joined to each other.

Next, the double-sided copper-clad substrate 7 'was subjected to an etching treatment using an aqueous cupric chloride solution as an etching solution. That is, the copper foil 1 on both sides is etched until the surface of the synthetic resin sheet 3 is exposed, and the wiring pattern 1 is pressed into the liquid crystal polymer and embedded on both sides.
A printed wiring board was obtained in which the tips of "a" were connected to each other.

The printed wiring board was subjected to a usual electrical check. As a result, it was found that all the connection portions were defective or unreliable. In addition, in order to evaluate the reliability of the connection between the wiring putters 1a ″, a hot oil test (a cycle of immersion in 260 ° C. oil for 10 seconds and a cycle of immersion in 20 ° C. oil for 20 seconds is one cycle). No defect was observed even after 500 times.

Fifth Embodiment FIG. 5 is a sectional view showing a main part of a printed wiring board according to this embodiment. That is, according to the case of the above-described Example 2, the electrolytic copper foil having the wiring pattern formed in a convex shape was
Manufactured sheets, on a predetermined position surface of the convex wiring pattern of these copper foils, printed a silver-based conductive paste using an epoxy resin as a binder via a metal mask, and dried the printed conductive paste, A conical conductor pump was formed (formed).

Thereafter, a liquid crystal polymer layer is interposed between the surfaces on which the conductor bumps of both copper foils are formed, positioned and arranged, and then press-integrated, and a double-sided copper-clad substrate having a convex wiring pattern embedded in the liquid crystal polymer layer. Was prepared. For this double-sided copper-clad substrate, a cupric chloride aqueous solution was used as an etching solution.
Etching was performed until the liquid crystal polymer layer was exposed to obtain a printed wiring board 8 'as shown in cross section in FIG.

In the manufactured printed wiring board 8 ', a part of the conductive bumps 6 penetrating the liquid crystal polymer layer 4 works for interlayer connection between the convex wiring patterns 1a and 1a', and the other part is a liquid crystal. The structure is exposed on the surface of the polymer layer 3 and can be used for connection terminals and the like.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. For example, a multilayer printed wiring board can be manufactured by a combination of the above-described steps or methods. The synthetic resin sheet may be a thermoplastic resin sheet such as a polycarbonate resin sheet or a prepreg.

[0055]

According to the first aspect of the present invention, the thin and high-density type in which the adjacent fine wirings are reliably insulated from each other and the bonding and integration with the highly reliable insulating resin layer are maintained. A printed wiring board can be provided with high yield.

According to the second to fourth aspects of the present invention, highly reliable connection between wiring pattern layers is ensured, and fine wiring is embedded in the outer surface of the insulating resin so as to be insulated and isolated from each other. A printed wiring board in which bonding and integrity with layers are reliably maintained can be obtained while omitting complicated means and the like.

Further, according to the first to fourth aspects of the present invention, since the outer wiring pattern is formed so as not to protrude from the surface of the printed wiring board, it becomes easy to form a solder resist by printing, for example. In soldering,
The occurrence of bridges between adjacent connection terminals at a narrow pitch is also avoided, and a compact or high-density wiring board with high reliability can be obtained in combination with the fine wiring patterning.

[Brief description of the drawings]

FIGS. 1A, 1B, 1C, 1D, and 1E are cross-sectional views of essential parts schematically showing a first embodiment example in the order of steps.

FIGS. 2 (a), (b), (c), (d), (e), and (f) are cross-sectional views of essential parts schematically showing a second embodiment example in the order of steps.

3 (a), 3 (b) and 3 (c) are cross-sectional views of essential parts schematically showing a third embodiment example in the order of steps.

4 (a) and 4 (b) are cross-sectional views of essential parts schematically showing a fourth embodiment example in the order of steps.

FIG. 5 is a sectional view of a principal part of a printed wiring board according to a fifth embodiment;

[Explanation of symbols]

 1, 1 '... conductive metal layer (copper foil) 1a, 1a', 1a "... convex wiring pattern 2a, 2b ... etching resist film 3 ... insulating resin layer 4 ... copper-clad substrate 5 ... ... Printed wiring board 5,5 '... Double-sided copper-clad board 6 ... Conductor bump 6' ... Conductor part 7,7 ', 9 ... Double-sided printed wiring board 8 ... Double-sided copper-clad multilayer board

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Ohira 3-28-7 Nakamagome, Ota-ku, Tokyo Yamaichi Electric Co., Ltd. F-term (reference) 5E317 AA24 AA30 BB01 BB02 BB12 BB14 BB25 CC22 CD25 GG17 5E339 AB02 AC01 AD01 AD03 AD05 BC01 BD02 BD06 BD11 BE11 CC00 CD01 CG01 EE01 EE10

Claims (4)

[Claims] 1. A step of performing selective masking on one main surface of a conductive metal foil to form a convex wiring pattern by half-etching; and a masking layer on the convexly formed wiring pattern surface. Removing, laminating and arranging the wiring pattern surface facing the main surface of the insulating resin layer, and embedding and integrating the convex wiring pattern into the insulating resin layer by pressing the laminate, Etching the conductive metal foil while leaving the wiring pattern embedded in the insulator layer to expose the wiring pattern to the surface of the insulating resin layer. 2. A step of performing selective masking on one main surface of the conductive metal foil to form a convex wiring pattern by half-etching, and a masking layer on the convexly formed wiring pattern surface. Removing, and providing conductive protrusions for interlayer conduction at required positions; positioning and laminating and arranging a conductive metal foil with the wiring pattern surface facing the main surface of the insulating resin layer; Pressing the body to embed the convex wiring pattern in the insulating resin layer, and integrating the conductive metal foil and the insulating resin layer while penetrating the conductive protrusions; Etching the conductive metal foil while leaving the wiring pattern, and exposing the wiring pattern to the surface of the insulating resin layer. 3. A step of performing masking on one main surface of the first conductive metal foil and half-etching to form a convex wiring pattern, and masking the convexly formed wiring pattern surface. Removing the layer and providing a first conductive projection for interlayer conduction at a required position; and placing the first conductive metal foil by facing the wiring pattern surface to the main surface of the first insulating resin layer. Positioning and laminating and arranging the first conductive metal foil while pressing the laminate to embed the convex wiring pattern in the first insulating resin layer and penetrating the first conductive protrusion; And a step of integrating the first insulating resin layer, and etching and removing the conductive metal foil while leaving the wiring pattern embedded in the first insulating layer, thereby forming the first wiring pattern.
Exposing on the surface of the insulating resin layer, providing a conductive protrusion for interlayer conduction at a required position on the exposed wiring pattern surface,
Positioning and laminating / arranging a second conductive metal foil provided with a convex wiring pattern by half-etching via a second insulating resin layer; and pressing the laminate to form a convex wiring pattern. Integrating the second conductive metal foil into the second insulating resin layer while embedding the second insulating resin layer in the second insulating resin layer, and penetrating the conductive protrusions; Etching the second conductive metal foil while leaving the wiring pattern embedded in the insulating resin layer to expose the wiring pattern on the surface of the insulating resin layer. 4. A step of performing masking on one principal surface of the first conductive metal foil to form a convex wiring pattern by half-etching; and masking the convex wiring pattern surface. Removing the layer and providing a first conductive projection for interlayer conduction at a required position; and placing the first conductive metal foil by facing the wiring pattern surface to the main surface of the first insulating resin layer. Positioning and laminating and arranging the first conductive metal foil while pressing the laminate to embed the convex wiring pattern in the first insulating resin layer and penetrating the first conductive protrusion; And a step of integrating the first insulating resin layer; and etching and removing the first conductive metal foil while leaving the wiring pattern embedded in the first insulating layer, thereby forming the wiring pattern into the first insulating resin layer. Exposing to the resin layer surface, the wiring pattern A first insulating resin layer surface exposed,
A second pattern in which a convex wiring pattern is provided by half-etching and a conductive projection for interlayer conduction is provided at a predetermined position;
Positioning, laminating and arranging the conductive metal foil through a second insulating resin layer, and embedding a convex wiring pattern in the second insulating resin layer by pressing the laminate, A step of integrating the second conductive metal foil with the second insulating resin layer side while penetrating the protrusion; a second conductive metal foil leaving a wiring pattern embedded in the second insulating layer; Removing the metal foil by etching to expose the wiring pattern on the surface of the insulating resin layer.