JPH08335759A - Printed wiring board and its production - Google Patents

Abstract

PURPOSE: To provide a high quality, highly reliable printed wiring board which can be produced without requiring any intricate process control, and a method for mass producing such printed wiring board with high yield. CONSTITUTION: The printed wiring board comprises a flexible wiring element board 6, hard wiring units 11, 12 disposed while being spaced apart planarly such that a flexible wiring element board region 6' is exposed, and an interlayer connection part for connecting the wiring layers of hard wiring units electrically. The interlayer connection is made by abutting the end face of conductive bumps 10 penetrating the insulator layers 8a, 8b (7a, 7b), i.e., the insulating adhesive layers, between the wiring pattern layers each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board and a method for manufacturing the same, and more particularly, to a printed wiring board which includes a rigid printed wiring unit and a flexible wiring unit and which can be bent, and a method for manufacturing the same. Regarding

[0002]

2. Description of the Related Art Conventionally, a foldable print having the following structure has been used as a circuit structure which also serves as a wiring connection portion which requires flexibility, a housing of an apparatus, or the like, or as a compact circuit device. Wiring boards are known. That is,
There is known a printed wiring board that is configured to be foldable by a flexible wiring base plate that is formed by stacking and integrating hard printed wiring units on a flexible wiring base plate surface, which are appropriately separated from each other in a plane, and forms the separated portion. .

FIG. 5 is a cross-sectional view showing the essential structure of such a bendable printed wiring board, in which 1 is a flexible wiring board provided with required wiring patterns 1a and 1b, and 2. 3 is on both main surfaces of the flexible wiring base plate 1,
The hard wiring units are integrally arranged with the insulating adhesive layer 4 interposed therebetween. The hard wiring units 2 and 3 are used as a unit, and the flexible wiring unit 1'exposed in a strip shape is formed as a bendable portion. In FIG. 5, 4a is a surface protective layer (coverlay film layer or insulating protective film layer), which can be left as a part of the insulating adhesive layer 4 and can also be used as this. In Units 2 and 3,
It is a through-hole connecting portion that forms an interlayer connection of the wiring patterns 1a, 1b, 2a, 3a.

A printed wiring board of this type is generally manufactured as follows. FIG. 6 is a cross-sectional view schematically showing the embodiment. First, insulating adhesive layers (sheets) 4 and 4a made of, for example, epoxy resin are preliminarily arranged on the flexible wiring base plate 1 surface. Position the hard copper foil-clad laminates (copper-clad laminates) 2 ', 3'provided with V-grooves or slits 2b, 3b for separation on the area surface corresponding to the foldable wiring unit 1'. ，
After placing and stacking, pressure and heat are integrated. Here, the V-grooves or slits 2b and 3b for separation are provided along the line separating from the wiring units 2 and 3 of the hard copper clad laminates 2'and 3 '. Further, if necessary, in the region corresponding to the exposed region (flexible wiring unit 1 ') of the flexible wiring base plate 1, the insulating adhesive layer 4 is partially selectively removed to form an opening / space portion. It is processed into a shape.

As described above, after the hard copper foil-clad laminates 2'and 3'are integrated on the surface of the flexible wiring base plate 1, the outermost copper foil is photoetched to obtain the required wiring pattern 2a, V-grooves or slits for separating the hard copper-clad laminates 2'and 3'while performing the 3a process and further performing the required through-hole connection 5 and external processing.
It is manufactured by separating and peeling off the non-circuit forming portion (area corresponding to the wiring unit 1 ') along 2b and 3b.

[0006]

However, in the above-mentioned printed wiring board and its manufacturing method, not only the manufacturing process is complicated, but there is a problem in mass productivity and cost.
There is also concern about the reliability between wiring pattern layers. That is, in forming the through hole connecting portion 5 between the wiring patterns 1a or 1b and the hard wiring units 2 and 3a in the hard wiring units 2 and 3, there are restrictions on the drilling process and the chemical plating process.
There are problems such as difficult process control and poor yield.

More specifically, the hard wiring units 2 and 3 are composed of, for example, a flexible wiring base plate 1 in the form of polyimide resin film-flexible epoxy resin adhesive layer-copper layer, polyimide resin. System or nitrile rubber type insulative adhesive layer 4 and hard copper clad laminates 2 ', 3'in the form of crow / epoxy resin-copper, which are laminated combinations of different material layers. Therefore, for example, when drilling is performed by drilling, it is substantially impossible to set appropriate processing conditions corresponding to each material, and it is difficult to form a hole having a good shape and the like.
Also, when a conductor layer is provided on the formed inner wall surface of the perforation by chemical plating or the like to form a so-called through-hole connecting portion 5, since the inner wall surface of the perforation is a laminated surface of different materials,
The plating adhesion is difficult, and it is difficult to generate and form a highly reliable connection part.

The present invention has been made in consideration of the above circumstances, and provides a high-quality and highly reliable printed wiring board which can be obtained without complicated process control and mass production of such a printed wiring board. Moreover, it is an object of the present invention to provide a manufacturing method capable of manufacturing with good yield.

[0009]

According to a first aspect of the present invention, a flexible wiring base plate and a planar wiring base plate region are exposed on at least one surface of the wiring base plate so as to expose a bendable wiring base plate region. A hard wiring unit that is separated and integrally laminated is provided, and an interlayer connecting portion that electrically connects wiring layers of the hard wiring unit, and the interlayer connecting portion is an insulator between wiring pattern layers. The printed wiring board is characterized in that the end faces of the conductive bumps through which the insulating adhesive layers forming the layers are inserted are brought into contact with each other.

According to a second aspect of the present invention, a step of laminating a conductive metal layer on at least one surface of a flexible wiring base plate with an insulating adhesive layer interposed therebetween, and pressurizing and integrating the laminated body to form a hard metal. A step of forming a conductive metal layer-clad laminate having a wiring portion; a step of wiring patterning the conductive metal layer of the conductive metal layer-clad laminate to form a hard wiring unit separately; A method of manufacturing a printed wiring board, the method comprising: forming a bendable wiring unit between hard wiring units, wherein electrical connection between wiring layers of the hard wiring unit is provided on one wiring pattern surface. The method for producing a printed wiring board is characterized in that the conductive bump tips having the insulating adhesive layer inserted therein are brought into contact with the opposing wiring pattern surfaces.

[0011]

According to the printed wiring board of the present invention, the electrical connection between the wiring pattern layers of the hard wiring unit is made by the conductive bump for pressing and inserting the interlayer insulating layer. In other words, the tip side of the conductive bump fixed and erected on one wiring pattern surface presses the interlayer insulator layer.
The wiring pattern surfaces are inserted through and are in contact with each other to form a highly reliable electrical and mechanical connection. Therefore, it can be handled with ordinary care, and the function as a bendable printed wiring board can be sufficiently retained and exhibited.

Further, according to the method for manufacturing a printed wiring board of the present invention, the electrical connection between the wiring pattern layers of the hard wiring unit is made by connecting the tip end side of the conductive bump fixed and planted on the wiring pattern surface. By pressing, the interlayer insulating layer is inserted and connected to the opposing wiring pattern surface. That is,
It is possible to obtain a printed wiring board having an electrically and mechanically reliable wiring pattern interlayer connecting portion with a high yield, while omitting complicated steps and operations such as drilling for connection and making conductive by plating.

[0013]

EXAMPLES Examples of the present invention will be described below with reference to FIGS. 1 to 4 which schematically show examples of manufacturing a printed wiring board according to the present invention.

First, a flexible wiring base plate 6 having a thickness of 0.025 mm, in which required wiring patterns 6a and 6b are provided on both main surfaces, and an insulating adhesive sheet having a thickness of about 0.05 mm, for example, thermoplastic resin. Polyimide film 7a, 7b,
Glass / epoxy resin prepreg 8a, 8b, and thickness
We prepared electrolytic copper foils 9a and 9b, which are commonly used in the manufacture of 35 μm printed wiring boards.

Here, the flexible wiring base plate 6 is manufactured as follows. For example, the process of printing and drying the conductive paste through the metal mask on the electrolytic copper foil surface is repeated 2 to 3 times to form the conductive bumps, and then the polyimide resin film and the electrolytic copper film are formed on the conductive bump forming surface. The foils are laminated and arranged, heated and pressed, and the polyimide resin film is inserted into the electroconductive copper foil surface side where the conductive bump tips are opposed to each other. In this way, a double-sided copper foil-clad board in which both electrolytic copper foils are electrically connected is created, and by patterning the wiring by performing photo-etching or the like on both sides of the double-sided copper foil-clad board, the conductive bumps are connected to the interlayer connection part 6c Thus, the double-sided flexible wiring base plate 6 is obtained. On the other hand, the double-sided flexible wiring base plate 6 is provided at a predetermined position on one main surface of the electrolytic copper foils 9a and 9b.
Conductive bumps 10 are in place in the same way as when creating the
Is provided in advance.

Next, the flexible wiring base plate 6,
Thermoplastic polyimide film 7a, 7b, glass / epoxy resin prepreg 8a, 8b, and electrolytic copper foil 9a, 9b
As shown in a sectional view in FIG. 1, they were stacked and arranged. Here, the thermoplastic polyimide films 7a and 7b are partially inserted into the hard wiring units 11 and 12, and the glass / epoxy resin prepregs 8a and 8b are partially planarized in advance. It was cut out and opened. That is,
The glass / epoxy resin prepregs 8a and 8b are opened to have a diameter corresponding to the area of the flexible wiring unit 6 '.

Thereafter, the laminated body is subjected to a heat / pressure molding treatment, and electrolytic copper foils 9a and 9b are provided on both sides of the flexible wiring base plate 6 via glass / epoxy resin prepregs 8a and 8b. Each of them was laminated and integrated. By this heating / pressurizing process, the conductive bumps 10 provided on the surfaces of the electrolytic copper foils 9a, 9b are inserted into the corresponding glass / epoxy resin-based prepregs 8a, 8b so that the flexible bumps face each other. A required interlayer connecting portion 10 'was formed by contacting the wiring patterns 6a and 6b of the wiring base plate 6 with each other.

Next, the electrolytic copper foils 9a and 9b are subjected to a required photo-etching treatment to obtain a hard wiring unit.
An outer layer circuit corresponding to 11 and 12 is formed. At this time, the flexible wiring base plate 6'which functions as a bendable region is protected from photoetching by the thermoplastic polyimide films 7a and 7b forming a so-called coverlay.

Further, the present invention can take the following modifications.

FIG. 2 shows a first modification, in which a hard wiring unit 11 is a flexible wiring base plate 6 in this configuration example.
It is provided only on one side of. Then, in this configuration example, electrolytic copper foils 9a and 9b forming part of the hard wiring unit 11 are formed.
Instead of the above, an embodiment in which a conductive bump 10 is provided on one wiring pattern surface of a double-sided conduction type wiring base plate 13 prepared by a method similar to that at the time of forming the flexible wiring base plate 6 is used.

Further, in FIG. 3, in contrast to the structure shown in FIG. 2, hard wiring units 11 and 12 are provided only on one side of the flexible wiring base plate 6.

Further, FIG. 4 omits the glass / epoxy resin prepregs 8a and 8b in the structure shown in FIG. 3, and also serves as an interlayer insulator layer for the thermoplastic polyimide films 7a and 7b as a cover lay. The adopted configuration is adopted.

Although the glass / epoxy resin prepreg is used as the insulating adhesive layer in the above, instead of this, for example, a polyphenylene sulfide resin film, an epoxy resin film, an acrylic resin film, a glass fiber reinforced polyimide prepreg is used. Similar results can be obtained by using Similar results can be obtained by using, for example, a polyphenylene sulfide-based resin film, an epoxy-based resin film, or an acrylic-based resin film instead of the thermoplastic polyimide-based film forming the coverlay. Also, the hard wiring units 11 and 12 are
After the formation of the outer layer circuit, a conductive bump 10 may be formed on the surface of a predetermined area, and the conductive bump 10 may be laminated and arranged on the surface of the insulating adhesive layer.

Further, the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be adopted without departing from the scope of the invention. For example, the insulating adhesive layer may be arranged by a general coating method, a printing coating method, or the like, instead of using films or sheets.

[0025]

As described above, in the printed wiring board according to the present invention, not only the preset position / area functions as a foldable area, but also a rigid board is provided irrespective of such a function and usage mode. Since the connection between the wiring pattern layers in the wiring unit is surely maintained, it is possible to operate as a highly reliable printed wiring board.

Further, in the method of manufacturing a printed wiring board according to the present invention, not only the complexity of the manufacturing process is greatly simplified, but also a highly reliable printed wiring board with a high yield can be obtained as described above. Can provide low cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an essential part schematically showing a first embodiment of a foldable printed wiring board according to the present invention.

FIG. 2 is a cross-sectional view of a main part schematically showing a second embodiment of a bendable printed wiring board according to the present invention.

FIG. 3 is a cross-sectional view of an essential part schematically showing a third embodiment of the bendable printed wiring board according to the present invention.

FIG. 4 is a cross-sectional view of a main part schematically showing a fourth embodiment of a bendable printed wiring board according to the present invention.

FIG. 5 is a cross-sectional view showing a structural example of a main part of a foldable printed wiring board.

FIG. 6 is a cross-sectional view showing an embodiment of a conventional method of manufacturing a bendable printed wiring board.

[Explanation of symbols]

1,6 ... Flexible wiring base plate 1 ', 6' ... Flexible wiring unit 1a, 1b, 6a, 6a ... Flexible wiring base plate wiring pattern 2,3,11 12, ... Hard wiring Units 2 ', 3' ... hard copper-clad laminate 2b, 3b ... slits or grooves for separation 4, 8a, 8b ... insulating adhesive layers 4a, 7a, 7b ... coverlay film 5, 6c, 10 '…… Through hole connection part 9a, 9b …… Copper foil 10 …… Conductive bump 13 …… Double sided conductive hard wiring board

Claims (2)

[Claims] 1. A flexible wiring base plate and a hard body integrally laminated on at least one surface of the wiring base plate so as to expose a bendable wiring base plate region so as to be planarly separated. A wiring unit, and an interlayer connecting portion for electrically connecting the wiring layers of the hard wiring unit, wherein the interlayer connecting portion has an insulating adhesive layer forming an insulating layer between wiring pattern layers inserted therethrough. A printed wiring board characterized in that the end faces of the conductive bumps are in contact with each other. 2. A step of laminating and placing a conductive metal layer on at least one surface of a flexible wiring base plate with an insulating adhesive layer interposed therebetween, and a hard wiring portion provided by pressing and integrating the laminated body. A step of forming a conductive metal layer-clad laminate, a step of wiring patterning the conductive metal layer of the conductive metal layer-clad laminate to form hard wiring units apart from each other, and between the hard wiring units A method of manufacturing a printed wiring board having a step of forming a foldable wiring unit in, wherein electrical connection between wiring layers of the hard wiring unit is performed,
A method for manufacturing a printed wiring board, characterized in that a conductive bump tip portion provided on one wiring pattern surface and having an insulating adhesive layer inserted therein is brought into contact with an opposing wiring pattern surface.