JP2003110240A - Composite wiring board and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and reliable composite wiring board suitable for high-density wiring, and to provide a method for manufacturing the composite wiring board. SOLUTION: In the composite wiring board, a hard printed-wiring board 7 having a wiring layer at least at one side and a flexible wiring board 1 having a wiring layer at least at one side are laminated via an insulating resin bonding sheet 5 having a conductive pillar 6 that is provided so that the wiring layers of both the boards are electrically connected. Additionally, in the composite wiring board and the manufacturing method thereof, an entire wiring pattern is divided into at least two wiring regions including a high-density wiring region and other wiring regions, and the flexible wiring board 1 should be laminated in the high-density wiring region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite wiring board and a method for manufacturing the same, and more particularly to a composite wiring board that is inexpensive and suitable for high-density wiring having high reliability, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the number of connection terminals of a semiconductor device or a semiconductor package has been rapidly increasing along with the degree of integration.
There is also used one having as many as 100 connecting terminals.
With the increase in the number of terminals, the method of arranging the terminals is shifting from the conventional peripheral arrangement to the grid-like arrangement in order to accommodate a large number of terminals in a package area as small as possible.

In order to connect to the connection terminals arranged in a grid like this, the connection terminals of the wiring board and the lead wires are also required to have extremely high density and accuracy. There is a demand for extremely high-density and high-definition arrangement rules with intervals of 50 μm or less.

As a conventional method for forming a multilayer wiring board, a plurality of wiring boards having adhesiveness, for example, laminated via insulating layers such as prepregs are mechanically integrated by heating and pressurizing, punching, and plating. It is general to electrically connect the layers by (plating through holes), but the wiring width and the wiring interval that can be achieved by this multilayering method are limited to about 100 μm. Furthermore, there are factors such as securing an area for arranging the through holes and routing wiring for bypassing the through holes, and it is extremely difficult to cope with the above high density wiring by such a method. is there.

On the other hand, as a wiring board for complying with the above-mentioned minute arrangement rule, a build-up board has been developed in which a double-sided printed wiring board is used as a core layer, and a thin insulating resin layer and a wiring layer are sequentially laminated on the core layer. , Is becoming popular. This build-up substrate is manufactured by sequentially repeating the necessary number of layers and stacking the following steps as one unit. (A) A photosensitive insulating material is laminated on the insulating resin layer by applying a photosensitive insulating material or sticking a sheet of the photosensitive insulating material. (B) A through hole is formed by irradiating the insulating resin layer with ultraviolet rays while applying a photomask and developing this. (C) The surface of the insulating resin layer is, for example, CrO ₃ and H ₂ SO.
_After being immersed in a liquid containing ₄ and chemically roughened, a desired wiring pattern is formed by plating.

However, there is a limit to the high-density wiring by the build-up substrate, and the wiring width and the wiring interval which can be achieved at the current technical level are each about 40 μm.
This is because in the build-up board, the insulating resin layer and the wiring layer are sequentially laminated, so that the surface of the insulating resin layer has unevenness under the influence of the unevenness due to the wiring pattern present in the lower layer. This is because it becomes extremely difficult to form a very fine wiring of 40 μm or less due to the unevenness. As a countermeasure against this, a method of forming a thick insulating resin layer and polishing the insulating resin layer after curing has been proposed, but if the resin layer becomes thick, it becomes difficult to form a small-diameter via hole, which impedes high-density wiring. At the same time, there is a drawback that the manufacturing cost increases due to the introduction of the polishing step, and it cannot be a satisfactory measure.

As described above, at the current technical level, there is a problem that even a build-up board cannot cope with a very fine arrangement rule of 40 μm or less. Also,
As the wiring density increases, it becomes difficult to form a desired wiring pattern with high accuracy over the entire surface of a large-sized wiring board.In addition, the difficulty of the sequential manufacturing method for the build-up board is added. Due to the occurrence of defects in the high-density wiring region, there is a problem that the product yield is lowered and the manufacturing cost of the wiring board is increased.

[0008]

SUMMARY OF THE INVENTION In view of the problems of the prior art described above, an object of the present invention is to provide an inexpensive and highly reliable composite wiring board suitable for high-density wiring and a method for manufacturing the same. It is in.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has provided a hard printed wiring board having a wiring layer on at least one surface and a flexible wiring board having a wiring layer on at least one surface. In a composite wiring board that is laminated via an insulating resin adhesive sheet having conductive pillars, the above problem is solved by dividing the entire wiring pattern into two or more regions and stacking the flexible wiring board in a small size. The present invention has been completed and the present invention has been completed based on such findings. That is, according to the present invention, the following composite wiring board and method for manufacturing the same are provided. (1) A hard printed wiring board having a wiring layer on at least one surface and a flexible wiring board having a wiring layer on at least one surface are provided with conductive pillars arranged so as to electrically connect the wiring layers of both boards. In a composite wiring board formed by laminating an insulating resin adhesive sheet, the entire wiring pattern has a high-density wiring area and a second wiring area.
A composite wiring board, characterized in that it is divided into the above wiring areas and arranged, and the flexible wiring board is laminated in a high-density wiring area. (2) The method for manufacturing a composite wiring board according to (1) above, which comprises the following steps. (A) A step of individually forming a high-density wiring pattern on at least one surface of the flexible sheet, (b) A step of forming a via hole penetrating the wiring layer and the flexible sheet in the flexible sheet on which the wiring layer is formed. ,
(C) a step of filling the via hole with a conductive substance to make the inside conductive, (d) a step of forming a through hole penetrating the adhesive sheet in the insulating resin adhesive sheet, (e) Filling the inside of the through hole with a conductive material so as to be exposed on each surface of the adhesive sheet, and drying the conductive material to form a conductive pillar; (f) Bonding with the conductive pillar formed. A step of cutting and dividing a sheet into a size that can be loaded on the wiring layer, and (g) the divided bonding so that one end of the conductive pillar and the wiring layer are electrically connected. A step of loading a sheet on the wiring layer, heating and pressurizing to temporarily bond in a semi-cure state, (h) a step of dividing a flexible tape to which the adhesive sheet is temporarily bonded to form a flexible wiring board, (i) The other end of the conductive pillar As the wiring layer of the rigid printed wiring board are electrically connected, the flexible wiring board via the adhesive sheet loaded on the printed wiring board, the step of bonding by heating and pressing. (3) As the flexible sheet, 35 mm, 48 mm, and 70 mm provided with sprocket holes at both ends
The method according to (2) above, wherein a reel tape having any width selected from the above is used and the reel tape is conveyed using the sprocket hole.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The composite wiring board of the present invention electrically connects a hard printed wiring board having a wiring layer on at least one surface and a flexible wiring board having a wiring layer on at least one surface to electrically connect the wiring layers of both boards. In the composite wiring board laminated by interposing the insulating resin adhesive sheet having the conductive pillars arranged as described above, the entire wiring pattern has two or more wiring areas of the high-density wiring area and the other wiring area. It is divided, and the flexible wiring board is laminated in a high-density wiring region on a hard printed wiring board.

In the present invention, the entire wiring pattern is divided into two or more wiring areas, for example, a high-density wiring area of 50 μm or less for mounting semiconductor packages arranged in a grid and other wiring areas, and Wiring patterns in the high-density wiring area are individually formed on the flexible sheet. By cutting this flexible sheet on which the divided wiring pattern is formed into a predetermined size and stacking it at a predetermined position on a hard printed wiring board through an insulating resin adhesive sheet having conductive pillars, high density can be obtained. The wiring pattern required for the wiring region is formed as an assembly of a plurality of small flexible wiring boards. Since the composite wiring board of the present invention is configured as an assembly of a plurality of small-sized flexible wiring boards as described above, the continuity inspection, the appearance inspection, etc. are performed before stacking at a predetermined position on the hard printed wiring board. As a result, only the defective wiring board can be eliminated. As a result, the entire board will not become unusable due to partial wiring failure, and it will be possible to load and stack it at a predetermined position on the rigid printed wiring board with high accuracy through image recognition, etc., improving the product yield. The composite wiring board can be obtained at low cost. The flexible substrate is suitable for forming fine wiring because the film has no irregularities, and moreover, it is continuously roll-to-roll,
Further, in the case of double-sided, two layers of wiring can be formed at one time, so that an extremely low cost can be expected. Further, by making the flexible wiring board small in size, it is possible to suppress warpage, peeling, and the like of the board caused by the difference in thermal expansion between the hard printed wiring board and the flexible wiring board, so that the reliability of the product is also improved.

The method for manufacturing the composite wiring board of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a conceptual diagram illustrating a method for manufacturing a composite wiring board according to the present invention. FIG. 2 is a conceptual diagram showing one embodiment of mounting the composite wiring board of the present invention.

In the present invention, as shown in FIG. 1A, a wiring pattern is individually formed on at least one surface of a flexible sheet and a via hole for interlayer connection is formed at a predetermined position by the following steps. Form. (A) A high-density wiring pattern is individually formed on at least one surface of a flexible sheet. (B) A via hole that penetrates the wiring layer and the flexible sheet is formed in the flexible sheet on which the wiring layer is formed. (C) The via hole is filled with a conductive material to make the inside of the hole conductive.

As a method of forming the wiring pattern, a conventionally known method such as photoetching can be used. For example, a flexible sheet having a conductive metal foil such as a copper foil attached to at least one surface thereof is prepared and the metal is formed. After screen-printing or laminating a dry film on the foil to form a photosensitive resist film, it is exposed and developed to be patterned. Then, the metal foil is selectively removed by etching with an etching solution such as ferric chloride solution, and then the resist is removed to form a predetermined wiring pattern. In order to increase the density of wiring, it is preferable to prepare a flexible sheet having metal foils attached to both sides and pattern the both sides to form a wiring pattern on both sides of the sheet. How many wiring regions the entire wiring pattern is divided into depends on the distribution of the wiring density of the wiring pattern and the like. For example, the wiring pattern is divided into a high-density wiring region having a wiring width and a wiring interval of 50 μm or less and other wiring regions. In consideration of the difference in thermal expansion from the printed circuit board, handling convenience, etc., the size of the wiring board to be divided may be set to about 10 to 65 mm and appropriately divided.

As a method of forming the via hole, a conventionally known method can be used. For example, a via hole penetrating the wiring pattern and the flexible sheet at a predetermined position of the wiring pattern by laser processing, photoetching or the like. To form. The diameter of the via hole is preferably small within a range that does not hinder the conductivity in the hole, and is usually 100 μm or less, preferably 50 μm or less. For example, the thickness of the flexible sheet is 50 to 7
If the diameter is about 5 μm, the via hole diameter is 50 to 100 μm.
If the diameter is about 25 to 50 μm, the via hole diameter can be about 20 to 50 μm. The via hole is filled with a conductive metal such as copper by plating, vapor deposition, sputtering or the like, or a conductive paste is pressed into the via hole using a mask and dried to make the inside of the hole conductive. Electrical connection between layers.

As the flexible sheet, a polyimide film, a polyamide film, a polyester film, a polytetrafluoroethylene film,
Examples include polyphenylene sulfide film,
For example, a polyimide film having a thickness of 25 to 75 μm can be preferably used. Since inorganic materials such as glass fibers interfere with laser processing and chemical etching, it is desirable not to use a sheet containing an inorganic material.

Examples of the conductive metal foil include copper foil, gold foil, nickel foil and the like. For example, the thickness is 8 to 25 μm.
m copper foil can be used suitably. In order to further miniaturize the wiring pattern, it is preferable to reduce the thickness of the metal foil within a range that does not affect mechanical strength and the like, and is usually 25 μm or less, preferably 15 μm or less. For example, if the thickness of the metal foil is set to about 15 to 18 μm, the wiring width and the wiring interval can be reduced to about 25 μm, and the wiring width and the wiring interval can be reduced to about 20 μm. The conductive powder used in the conductive paste, copper, silver, nickel, gold, solder,
Powders such as palladium are listed, and as the binder,
Examples thereof include polyimide resin, polyamide resin, urea resin, melamine resin and phenol resin.

In the present invention, next, as shown in FIG. 1 (b), through holes are formed in the insulating resin adhesive sheet by the following steps, and a conductive substance is filled in the through holes to conduct the conductive material. After forming the conductive pillar, the flexible pillar is cut into a predetermined size so that it can be loaded on each wiring layer formed on the flexible sheet. (D) A through hole is formed in the insulating resin adhesive sheet to penetrate the adhesive sheet. (E) A conductive substance is filled in the through hole so as to be exposed on each surface of the adhesive sheet, and the conductive substance is dried to form a conductive pillar. (F) The adhesive sheet on which the conductive pillar is formed is cut and divided into a size that can be loaded on the wiring layer.

As a method of forming the through hole, a conventionally known method can be used, for example, a through hole penetrating the adhesive sheet is formed by punching, chemical etching, plasma etching or the like. In the through hole, for example, a method of press-fitting a conductive paste using a mask having the same opening pattern as the adhesive sheet,
The conductive paste is filled using a conventionally known method such as screen printing or a method of filling the conductive paste using a dispenser, and this is dried to form conductive pillars to make the inside of the hole conductive. In order to obtain good contact with the wiring layer, the conductive pillar is formed so that each end is exposed on each surface (front and back) of the adhesive sheet, and if necessary, by a metal brush or the like. Polish and shape into bumps. As the conductive paste, the same conductive paste as that used for making the via holes conductive can be used.

As the insulating resin adhesive sheet, various thermoplastic resins such as epoxy-modified polyimide, epoxy-based, acrylic-based, polyimide-based or thermosetting resin sheets can be used. In the present invention, the hard printed wiring board and the flexible wiring board are arranged so as to face each other with the adhesive sheet interposed therebetween, and they are heated and pressed to bond them. It is preferable to absorb in this adhesive sheet. For this reason, the thickness of the adhesive sheet is preferably thin within a range in which the insulating property can be maintained, but it is at least the sum of the thicknesses of the wiring layers of both substrates and is usually 20 to 100 μm, preferably 20. ~
It is about 40 μm. The adhesive sheet has the same size as that of a predetermined size that can be loaded on each wiring layer formed on the flexible sheet, for example, if the size of the flexible substrate on which the wiring layer is formed is 20 mm square. Two
It is cut or divided into 0 mm square or slightly smaller 19.5 mm square, and the cutting method is not particularly limited, and a conventionally known method such as an ultrasonic cutter or a punching die can be used.

In the present invention, next, as shown in FIG. 1 (d), the insulating resin adhesive sheet was temporarily joined to the flexible sheet in a semi-cure state by the following steps, and this was obtained after being divided. The flexible wiring board is joined to the rigid printed board via the insulating resin adhesive sheet. It should be noted that FIG. 1C shows a commercially available hard printed circuit board. (G) The divided adhesive sheet is loaded on the wiring layer so that one end of the conductive pillar and the wiring layer are electrically connected to each other, and the adhesive layer is heated and pressed to temporarily bond in a semi-cured state. To do. (H) The flexible tape to which the adhesive sheet is temporarily joined is divided to form a flexible wiring board. (I) The flexible wiring board is loaded on the printed wiring board via the adhesive sheet so that the other end of the conductive pillar and the wiring layer of the hard printed wiring board are electrically connected to each other, Join by heating and pressing.

As a method for temporarily joining the insulating resin adhesive sheet to the wiring layer on the flexible sheet, a conventionally known method can be used. For example, a flip chip bonder (Miss FA Co., Ltd.) or the like can be used. Image-recognition using marks, etc., and resin bonding to be used after stacking on a predetermined wiring layer on a flexible sheet so that the wiring layer and one end of the conductive pillar are electrically connected. The heating and pressurizing conditions are appropriately set according to the type of the sheet, and the resin is semi-cured and temporarily joined. For example, when an epoxy resin adhesive sheet is used, it is heated to about 60 to 100 ° C. and pressurized to about 0.01 to 0.5 MPa to temporarily bond the resin in a semi-cured state. In order to accurately load the adhesive sheet at a predetermined position on the wiring layer, it is preferable to form a reference mark for alignment by punching or the like.

The flexible tape to which the insulating resin adhesive sheet is temporarily joined is cut and divided into a predetermined size for each wiring layer in order to form a plurality of small-sized flexible wiring boards. The cutting method is as follows. There is no particular limitation, and a conventionally known method such as an ultrasonic cutter or a punching die can be used.

As a method for bonding the flexible printed circuit board to which the insulating resin adhesive sheet is temporarily bonded and the rigid printed circuit board, a conventionally known method can be used. For example, both boards are laminated on a press plate via a cushion material. After sandwiching the body, heat according to the type of resin adhesive sheet used.
The pressurizing condition is appropriately set and the resin is bonded in a cured state. For example, when an epoxy resin adhesive sheet is used, it is heated to about 150 to 200 ° C. and 0.5 to 5 M.
Pressurize to about Pa and join. By this heat and pressure, the adhesive sheet is cured and cured, and the conductive pillars are joined to the opposing wiring layers while being plastically deformed. As the cushion material, it is preferable to use a stainless plate, a brass plate, a polyimide resin plate, or the like, which is less likely to change in size or deform.

As the printed wiring board, a board having a normal wiring density can be used, and an inexpensive commercially available wiring board (single-sided or double-sided wiring board, if necessary, multilayer wiring board), for example, glass-epoxy type, glass It is preferable to use a printed wiring board using a hard or rigid substrate such as a bismaleimide triazine type, a glass-polyimide type, or a ceramic type.

The shape of the flexible tape is as follows.
Although not particularly limited, in the present invention, the flexible tape is preferably a reel-shaped tape having sprocket holes at both ends, and particularly preferably has a width of 35 mm.
mm, 48 mm, or 70 mm reel tape is used. By using a reel tape with sprocket holes on both ends, the tape auto bonding (TAB) method can be adopted, and the reel tape can be automatically transported (sending / winding) using the sprocket holes. The production efficiency of the composite wiring board can be significantly improved. When forming a wiring layer on the reel-shaped tape, each wiring pattern is formed on the basis of the sprocket hole so that the TAB method can be adopted. Although the reels may be changed for each wiring pattern, it is inexpensive and efficient to form all the wiring patterns on one reel. For temporary bonding of the insulating adhesive sheet to each wiring layer, the reel tape is automatically conveyed using the sprocket hole, and the adhesive sheet is loaded at a predetermined position of the wiring layer by image recognition using a flip chip bonder or the like. Then, heat and pressure are applied. After the adhesive sheets are temporarily joined, a continuity inspection and an appearance inspection are performed, and marking makes it possible to distinguish good products from defective products. The reel-shaped tape to which the adhesive sheet is temporarily joined is automatically conveyed using the sprocket hole, and only the non-defective board is cut out to a predetermined size with reference to the sprocket hole, and the obtained flexible wiring board is adsorbed. It is conveyed by a tool or the like and is loaded on a predetermined position of a hard printed wiring board by image recognition, and heated and pressed to bond. After heating and pressurizing and bonding, voids are removed from the bonding surface through a hot roller, if necessary. Since the flexible wiring board is small, it can be accurately loaded at a predetermined position by image recognition, and voids can be easily removed from the joint surface.

As described above, the present invention is characterized in that the flexible wiring board is divided into small wiring boards and laminated on the printed wiring board. For example, when polyimide is used for the flexible substrate and glass epoxy is used for the rigid printed circuit board, the linear expansion coefficient around 25 ° C is about 8 ppm / ° C for polyimide and about 14 ° C for glass epoxy.
Since it is ˜17 ppm / ° C., if both are heat-integrated via an adhesive sheet, warpage of the substrate due to the difference in thermal expansion between the two and stress to the adhesive sheet occur, but the flexible wiring board is divided into small pieces. Thereby, the warp of the substrate is suppressed, the stress on the adhesive sheet is relieved, and the peeling of the substrate during use is suppressed, and the reliability of the composite wiring substrate is improved.

[0028]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 A glass epoxy substrate (manufactured by Matsushita Electric Works, Ltd.) having a thickness of 0.5 mm and having wiring patterns formed on both sides was prepared, and wiring patterns were formed on both sides, and both ends were vertically and horizontally elongated at a pitch of 4.75 mm. A polyimide flexible tape having a width of 35 mm and a thickness of 50 μm, each having a sprocket hole of 1.42 mm, was prepared. 18μ thick on both sides of this tape
m copper foil is pasted, a wiring pattern with a minimum wiring width of 30 μm and a minimum wiring interval of 30 μm is formed by using a photo-etching method, and laser irradiation is performed to form a via hole of 80 μmφ, and then a via hole is formed by electroless plating. Part, the wiring patterns on both sides were electrically connected. The connection pad to be the joint with the conductive pillar of the adhesive sheet is 150
The size is μmφ. On the other hand, the epoxy-based insulating resin adhesive sheet (DF-400 manufactured by Hitachi Chemical Co., Ltd.)
A 100 μmφ through hole is formed at a predetermined position by punching, and a conductive resin paste (T-
3030 Sumitomo Metal Mining Co., Ltd. was filled. Also,
An alignment reference mark was formed on the adhesive sheet by punching. This adhesive sheet is heated at 100 ° C. for 5 minutes to temporarily harden the paste, and then 19.5 m with a mold.
I punched it in m square. The flexible tape is automatically conveyed through a sprocket hole, and the cut adhesive sheet is loaded on the tape by image recognition using a flip chip bonder for TAB (manufactured by Miss FA Co.).
After sticking under conditions of ℃, 0.2 MPa, 2 seconds, it was wound into a reel. The wound reel was subjected to continuity inspection and visual inspection, and defective products could be marked and identified. Next, the reel-shaped tape with the adhesive sheet is conveyed into a punching die using a sprocket hole, a good product is automatically discriminated and punched out into a 20 mm square, and then this is conveyed with a suction tool to perform hard printing. It was loaded at a predetermined position on the wiring board by image recognition. 180 ° C for both wiring boards
After pasting under conditions of 0.5 MPa for 30 seconds, the voids were removed by passing through a hot roller to produce a composite wiring board. This wiring board did not cause swelling or peeling even under the soldering conditions of electronic parts, and did not cause defects such as peeling even when the temperature cycle of −55 to 125 ° C. was repeated 1000 times.

[0030]

As described above, according to the present invention, a composite wiring board which is inexpensive and has high reliability and which is suitable for high density wiring can be obtained.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating a method for manufacturing a composite wiring board according to the present invention.

FIG. 2 is a conceptual diagram showing one embodiment of mounting of the composite wiring board of the present invention.

[Explanation of symbols]

1 Flexible wiring board 2 wiring layers 2a Vialand 3 wiring layers 3a Vialand 4 via holes 5 Insulating resin adhesive sheet 6 Conductive pillar 7 Rigid printed circuit board 8 wiring layers 8a Vialand 9 wiring layers 9a Vialand 10 through holes 11 cushion board 12 Press plate 13 Semiconductor elements 14 Connection pad 15 Conductive bump 16 solder balls 17 Solder resist

Claims (3)

[Claims] 1. A conductive pillar in which a hard printed wiring board having a wiring layer on at least one surface and a flexible wiring board having a wiring layer on at least one surface are arranged so as to electrically connect the wiring layers of both boards. In a composite wiring board laminated by interposing an insulating resin adhesive sheet having the above, the entire wiring pattern is divided and arranged in two or more wiring areas of a high-density wiring area and other wiring areas. Is laminated in a high-density wiring region, a composite wiring board. 2. The method for manufacturing a composite wiring board according to claim 1, comprising the following steps. (A) A step of individually forming a high-density wiring pattern on at least one surface of the flexible sheet, (b) A step of forming a via hole penetrating the wiring layer and the flexible sheet in the flexible sheet on which the wiring layer is formed. ,
(C) a step of filling the via hole with a conductive substance to make the inside conductive, (d) a step of forming a through hole penetrating the adhesive sheet in the insulating resin adhesive sheet, (e) Filling the inside of the through hole with a conductive material so as to be exposed on each surface of the adhesive sheet, and drying the conductive material to form a conductive pillar; (f) Bonding with the conductive pillar formed. A step of cutting and dividing a sheet into a size that can be loaded on the wiring layer, and (g) the divided bonding so that one end of the conductive pillar and the wiring layer are electrically connected. A step of loading a sheet on the wiring layer, heating and pressurizing to temporarily bond in a semi-cure state, (h) a step of dividing a flexible tape to which the adhesive sheet is temporarily bonded to form a flexible wiring board, (i) The other end of the conductive pillar As the wiring layer of the rigid printed wiring board are electrically connected, the flexible wiring board via the adhesive sheet loaded on the printed wiring board, the step of bonding by heating and pressing. 3. As the flexible sheet, a reel tape having sprocket holes at both ends and having a width selected from 35 mm, 48 mm, and 70 mm is used, and the reel tape is transported. The method according to claim 2, which is performed by using the sprocket hole.