JP2004055980A - Multilayer flexible wiring board and manufacture thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer flexible wiring board which improves reliability, is more thinned and attains compaction, and to provide manufacture thereof. <P>SOLUTION: In the multilayer flexible wiring board, first thermoplastic resin thin layers 8a, 8b and 8c are used as layer insulators 8, a plurality of wiring pattern 9a, 9b, 9c layers are incorporated, and a projecting conductor 10 projecting over surfaces of the wiring patterns 9a, 9b and 9c electrically connects the wiring patterns 9a, 9b and 9c through the layer insulators 8, and laminated contacting surfaces of the layer insulator layers 8a, 8b and 8c are bonded and integrated through a second thermoplastic resin layer 11 whose fusing point is lower than that of the first thermoplastic resin 8. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multilayer flexible wiring board and a method for manufacturing the same, and more particularly, to a high-density wiring type, highly reliable multilayer flexible wiring board with a reduced thickness and a method for manufacturing the same.
[0002]
[Prior art]
As electronic devices become shorter, lighter, and thinner, wiring boards for forming electric circuits are required to have not only higher density wiring, shorter, lighter, and thinner but also more flexible. In response to such demands, multilayer flexible wiring boards have been developed as shown in FIG. In FIG. 3, interlayer insulating layers 20 and 21 are made of a polyimide resin film having a thickness of about 25 μm, and a wiring pattern 22 is formed between the layers, and an interlayer connection conductor 23 electrically connects the wiring patterns 22 to each other. Reference numeral 24 denotes a polyimide resin cover film having a thickness of about 25 μm that covers the outer layer wiring pattern formation surface. Here, the interlayer insulator layers 20 and 21 and the interlayer insulator layer 21 and the cover film 24 are laminated via a thermosetting adhesive layer (not shown). These via connection types are performed by embedding a conductor or forming a plated film on the inner wall surface of the through hole.
[0003]
And this kind of multilayer flexible wiring board is manufactured as follows. First, a copper foil bonded sheet is prepared by bonding a copper foil having a thickness of about 12 to 18 μm to a main surface of a thermosetting film 20 of, for example, a polyimide resin having a thickness of about 25 μm via an adhesive layer. Next, a predetermined area of the copper foil-bonded sheet is perforated to form a through hole for interlayer connection, and then the inner wall surface of the through hole is made into a plated conductor or filled with a conductive composition to form an interlayer connection conductor. 23 is arranged. After that, the wiring pattern 22 is formed by performing a photo-etching process, and the first flexible wiring layer 20 in which the wiring patterns 22 on both surfaces are connected is obtained.
[0004]
On the other hand, a copper foil-bonded sheet is prepared by bonding a copper foil having a thickness of about 12 to 18 μm to one principal surface of a thermosetting film 21 of, for example, a polyimide resin having a thickness of about 25 μm via an adhesive layer. Next, a predetermined area of the copper foil-bonded sheet is perforated to form a through hole for interlayer connection, and then the inner wall surface of the through hole is made into a plated conductor or filled with a conductive composition to form an interlayer connection conductor. 23 are formed. Thereafter, the copper foil is subjected to a photo-etching process to form a second flexible wiring layer 21 having an interlayer connection conductor 23 connected to the wiring pattern 22. Also, for mounting electronic components, a cover sheet 24 made of a polyimide resin and having a thickness of about 15 μm, which is formed by punching and pressing a required area, is prepared.
[0005]
The first flexible wiring layer 20, the second flexible wiring layer 21, and the cover sheet 24 prepared as described above are aligned and stacked. At this time, a thermosetting adhesive layer is interposed between the flexible wiring layers 20 and 21 and between the flexible wiring layers 21 and the cover sheet 24 so as not to hinder the electrical connection. . Then, the laminated arrangement body is subjected to hot press working, and these are joined and integrated to produce a multilayer flexible wiring board.
[0006]
Further, as a means for simplifying the structure of the interlayer connection, there is also known a method of showing a main part in FIGS. 4A, 4B and 4C. First, a projecting conductor 26 is formed on a predetermined area surface of a copper foil 25 having a thickness of about 15 μm using a conductive composition, a conductive metal, or the like as a material. Next, a thermoplastic resin layer 27 having a thickness of about 25 μm and a copper foil 25a having a thickness of about 15 μm are sequentially laminated on the surface of the copper foil 25 on which the protruding conductor 26 is formed. Thereafter, the laminate is joined by heat pressing to form a double-sided copper foil bonded plate in which the double-sided copper foils 25 and 25a are electrically connected by the protruding conductors 26 penetrating the thermoplastic resin layer 27. I do. The double-sided copper foils 25 and 25a of the double-sided copper foil-attached plate are subjected to an etching treatment to form a wiring pattern. This method has attracted attention as a means suitable for productivity and high-density wiring patterning because the interlayer connection conductor 26 can be easily and finely formed.
[0007]
[Problems to be solved by the invention]
Since the multilayer flexible wiring board is compact and flexible, it contributes to shortening and lightening of electronic devices to be used, for example, digital cameras and mobile phones, but on the other hand, the following problems are observed. . That is, in the configuration shown in FIG. 3, a configuration in which a thermosetting adhesive layer is interposed between the flexible wiring layers 20 and 21 and between the surfaces where the flexible wiring layer 21 and the cover sheet 24 face each other. I am taking it. By the way, the thermosetting resin film needs to have a certain thickness, and in joining and integrating the laminated arrangement, sufficient melting and fluidity of the interposed adhesive layer and heat for securing thermosetting are required. Press working is performed. At the stage of pressurization and heating, there is a possibility that the protruding wiring pattern 22 may be displaced or the like, and as a result, the reliability of the manufactured multilayer flexible wiring board is impaired. Or a decrease in manufacturing yield.
[0008]
In addition, when the thickness of the thermosetting adhesive layer to be interposed is increased in order to secure strong bonding, not only does the thinning of the multilayer flexible wiring board be impaired, but also in the stage of the hot press processing. Is promoted. In general, a thermosetting adhesive layer is required to have flame retardancy. Therefore, for example, a flame retardant such as a halogen compound or a phosphorus compound is added and blended. Not only raises environmental problems but also may adversely affect the electrical characteristics of the wiring board itself.
[0009]
On the other hand, in the multilayer flexible wiring board formed by the method shown in FIG. 4, the copper foil (wiring pattern) is formed by using the softening and melting properties of the thermoplastic resin layer 27 constituting the interlayer insulator. It can be joined to layer 27. However, depending on the selection of the thermoplastic resin, there is a concern that the wiring pattern may be displaced due to melting deformation or the like, and there are problems such as difficulty in securing sufficient bonding strength or failure in securing sufficient heat resistance. Therefore, there is a problem in terms of yield and reliability.
[0010]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a multilayer flexible wiring board that is highly reliable, thinner and more compact, and a method of manufacturing the same.
[0011]
[Means for Solving the Problems]
According to the present invention, a wiring pattern is formed on both main surfaces of a first thermoplastic resin layer, and an interlayer connection conductor penetrates the first thermoplastic resin layer between the wiring patterns to electrically connect the wiring pattern layers to each other. A first thermoplastic resin layer having a lower melting point than the first thermoplastic resin layer in a surface region adjacent to the wiring pattern on at least one of the main surfaces and having a flat surface. Flexible wiring base plate,
A wiring pattern is formed on one main surface of the third thermoplastic resin layer, and a second flexible wiring base plate formed by penetrating the third thermoplastic resin layer from the wiring pattern side to the other main surface. ,
It is characterized by being laminated on at least one main surface of the first flexible wiring base plate while being in contact with the other main surface of the second flexible wiring base plate via the second thermoplastic resin layer. In a multilayer flexible wiring board.
[0012]
Further, a thin layer of the first thermoplastic resin is used as an interlayer insulator, a plurality of wiring pattern layers are built-in, and a projecting conductor projecting from the wiring pattern surface penetrates the interlayer insulator to form a wiring pattern layer. A multilayer flexible wiring board for electrical connection, wherein a laminated contact surface between the interlayer insulator layers is joined and integrated via a second thermoplastic resin layer having a melting point lower than that of the first thermoplastic resin. It is a multilayer flexible wiring board characterized in that it is formed.
[0013]
Further, in the multilayer flexible wiring board according to the invention, at least the first thermoplastic resin is a liquid crystal polymer.
[0014]
Further, in the manufacturing method of the present invention, the wiring pattern is formed so as to protrude on at least one main surface of the first thin thermoplastic resin layer, and the projecting interlayer connection conductor penetrates the first thermoplastic resin layer. Covering a wiring pattern forming surface of a first flexible wiring substrate having a second thermoplastic resin layer having a melting point lower than that of the first thermoplastic resin to a substantially uniform thickness for filling the wiring pattern. Slashing the coated second thermoplastic resin layer surface to expose the wiring pattern surface to the same plane; and providing a first thermoplastic resin on the exposed wiring pattern surface of the first flexible wiring board. Positioning and laminating a non-wiring pattern forming surface of a second flexible wiring substrate having a wiring pattern and a projecting interlayer connection conductor penetrating in a thickness direction on one main surface of the thin layer; Lamination And bonding the first thermoplastic resin thin layers to each other via the second thermoplastic resin layer by applying pressure in the opposite direction to produce a multilayer flexible wiring board. is there.
[0015]
Further, a first flexible film having a wiring pattern protrudingly formed on at least one main surface of the first thermoplastic resin thin layer and having a projecting interlayer connection conductor penetrating the first thermoplastic resin layer. A step of coating and disposing a second thermoplastic resin layer having a melting point lower than that of the first thermoplastic resin on the wiring pattern forming surface of the wiring element plate to a substantially uniform thickness for filling the wiring pattern; A step of subjecting the arranged second thermoplastic resin layer surface to slash processing to expose the wiring pattern surface to the same plane; and a step of forming a first thermoplastic resin thin layer on the exposed wiring pattern surface of the first flexible wiring substrate. Positioning and laminating a non-conductive foil-bonding surface of a second flexible wiring base plate having a protruding interlayer connection conductor having a conductive foil bonded to one main surface thereof and having a protruding interlayer connection conductor penetrating in a thickness direction; , The laminated body in the laminating direction Pressurizing and joining the first thermoplastic resin thin layers via the second thermoplastic resin layer, and wiring patterning the conductive foil of the second flexible wiring base plate. A method for manufacturing a multilayer flexible wiring board.
[0016]
Further, a first flexible film having a wiring pattern protrudingly formed on at least one main surface of the first thermoplastic resin thin layer and having a projecting interlayer connection conductor penetrating the first thermoplastic resin layer. Exposing the wiring pattern forming surface of the wiring base plate, filling and arranging a second thermoplastic resin layer having a lower melting point than the first thermoplastic resin, and flattening the surface; Non-wiring of a second flexible wiring substrate having a wiring pattern and an interlayer connection conductor penetrating in the thickness direction on one principal surface of the first flexible wiring substrate flattened by filling and disposing resin. A step of positioning and laminating a pattern forming surface, and a step of pressing the laminate in the laminating direction to join and integrate the first thermoplastic resin thin layers via the second thermoplastic resin layer. Multi-layer frame A method for producing a reluctance wiring board.
[0017]
Further, in the above-described method for manufacturing a multilayer flexible wiring board, the thickness of the first thermoplastic resin layer forming the flexible wiring board is 25 to 200 μm.
[0018]
Further, in the above-mentioned method for producing a multilayer flexible wiring board, at least the first thermoplastic resin is a liquid crystal polymer.
[0019]
That is, the invention according to the present application is to form an interlayer insulator with a thermoplastic resin having a relatively high melting point and excellent heat resistance, and between each resin layer forming the interlayer insulator, a relatively low melting point. The key is to easily and firmly join and integrate under a more relaxed condition by interposing a thermoplastic resin layer. Along with such a configuration, with the configuration having the same number of wiring pattern layers, the overall thickness is reduced to easily achieve a reduction in size and weight, while achieving excellent reliability such as electrical characteristics and flexibility. It is intended to provide a multi-layer flexible wiring board having high performance.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2A, 2B, 2C, and 2D.
[0021]
FIG. 1 is an enlarged cross-sectional view illustrating a main part of a multilayer flexible wiring board according to an embodiment. In FIG. 1, an interlayer insulating layer 8 is formed of a first thermoplastic resin layer 8a of a liquid crystal polymer film having a thickness of 25 to 200 μm, for example, a BIAC film (trade name) or a Vexta film (trade name) having a melting point of 335 ° C. 8b and 8c are laminated, each wiring pattern layer 9a and 9b is sandwiched and built in the interlayer insulating layer 8, and a wiring pattern layer 9c is formed on the surface of the interlayer insulating layer 8. Here, each wiring pattern 9a, 9b, 9c is provided with a required electrical connection by a protruding connection conductor 10 projecting from the surface of the wiring pattern 9a, 9c and penetrating the first thermoplastic resin layer 8a, 8b, 8c. Connection is made.
[0022]
That is, the front end side of the protruding connection conductor 10 such as a conductive bump printed in a substantially conical or pyramid shape in the interlayer insulator 8 or a metal protrusion that is selectively overgrown is penetrated. And electrically connected to the wiring patterns 9a and 9b. Further, the first thermoplastic resin layers 8a, 8b, 8c of the liquid crystal polymer film forming the interlayer insulator layer 8 have a thickness of 25 to 200 μm and are interposed between the laminated contact surfaces, for example, It is joined and integrated via a second thermoplastic resin layer 11 formed of a C type film having a melting point of 325 ° C.
Note that a configuration in which a cover film (not shown) is further coated on the surface on which the exterior wiring pattern 9c is formed may be employed.
[0023]
More specifically, in the multilayer flexible wiring board according to this embodiment, the first thermoplastic resin layers 8a, 8b, and 8c have a lower melting point than the first thermoplastic resin layers 8a, 8b, and 8c. It is characterized in that it has a configuration in which it is joined and integrated via a second thermoplastic resin layer 11 made of a plastic resin. In this configuration example, the thickness of the multilayer flexible wiring board (four-layer type) is, for example, about 160 μm, and the conventional multilayer flexible wiring board (interlayer insulator is made of a polyimide resin thermosetting resin layer. Compared with the case where the thickness of the pattern (4 layer type) is about 180 μm, it can be made about 20 μm thinner, and it is also confirmed that the wiring patterns 9 a and 9 b do not shift in position and exhibit a highly reliable function. Was. In FIG. 1, reference numeral 12 denotes a via-type terminal for mounting electronic components.
[0024]
In the multilayer flexible wiring board having the above configuration, the first thermoplastic resin forming the interlayer insulating layer 8 is, for example, phenoxy resin, polyether sulfone resin, polysulfone resin, polyphenylene sulfone resin, polyphenylene sulfide resin, polyphenylene Examples thereof include an ether resin, a polyetherimide resin, a thermoplastic polyimide resin, a liquid crystal polymer, and a polytetrafluoroethylene resin. Further, the second thermoplastic resin layer 11 for joining and integrating the first thermoplastic resin layers forming the interlayer insulator layer is basically the above-mentioned resins. That is, the first thermoplastic resin layer 8 and the second thermoplastic resin layer 11 are relative to each other, and are preferably about 10 to 40 ° C. with respect to the selected first thermoplastic resin layer 8. The second thermoplastic resin layer 11 of a thermoplastic resin having a melting point as low as about 20 to 30 ° C. is selected. In particular, selection of a liquid crystal polymer is advantageous because of its excellent heat resistance, electrical insulation properties, dimensional stability, and the like.
[0025]
As a modified example, different materials can be selected for the first thermoplastic resin layers 8a, 8b, 8c. For example, the layer 8b may be used as a core layer and have a higher melting point than the layers 8a and 8c laminated on both surfaces thereof. Also in this case, a resin having a lower melting point is used for the second thermoplastic resin layer than for the first thermoplastic resin layer.
[0026]
The thickness of the first thermoplastic resin layers 8a, 8b, 8c varies depending on the number of wiring pattern layers, the thickness and specifications of the intended multilayer flexible wiring board, but is generally about 25 to 200 μm. . Further, the wiring patterns 9a, 9b, 9c on the main surfaces of the first thermoplastic resin layers 8a, 8b, 8c are formed by, for example, selective etching of the adhered copper foil, pressure bonding of the wiring pattern formed in advance, Alternatively, it is formed in a projecting manner by screen printing of a conductive paste or the like. The projecting wiring patterns 9a, 9b, 9c are pressurized and pressed in the thickness direction of the first thermoplastic resin layers 8a, 8b, 8c to adjust the projecting height to a low level. It also contributes to making the multilayer flexible wiring board thinner.
[0027]
The second thermoplastic resin layer 11 inserted between the surfaces where the first thermoplastic resin layers 8a, 8b and 8c are in contact with each other and contributing to the joint integration of the first thermoplastic resin layers 8a, 8b and 8c It is necessary to avoid trouble. That is, at least the surfaces of the wiring patterns 9a and 9b for interlayer connection are flush with the surface of the second thermoplastic resin layer 11 so as to be exposed in a state where the insulating coating by the second thermoplastic resin layer 11 is substantially avoided. Is adopted.
[0028]
Here, the same flat surface of the wiring patterns 9a and 9b and the second thermoplastic resin layer 11 can be formed by the following means. The first means is to press-fit a second thermoplastic resin film that is about 5 to 10 μm thicker than the height of the projecting wiring patterns 9a and 9b on the surfaces of the wiring patterns 9a and 9b and press-fit. The second thermoplastic resin film is selectively ground by slash processing to have the same flat surface as the wiring patterns 9a and 9b. The second means is to fit and dispose a second thermoplastic resin film punched and processed in a reverse pattern with respect to the wiring patterns 9a and 9b, and press-fit and fill. In this case, the wiring pattern 9a, 9b is pressed into the first thermoplastic resin 8b layer to form the same flat surface after the second thermoplastic resin film processed into the reverse pattern is fitted and arranged in a fitting manner. Good.
[0029]
Prior to the formation of the wiring pattern 9c in the outermost layer, if necessary, a perforation process for forming the mounting via connection terminal portion 12, a plating inner wall surface is made conductive by a carbon dioxide laser, a YAG laser, or the like. . Then, the required copper wiring pattern 9c is formed by photo-etching the outermost copper foil.
[0030]
Next, an example of a method for manufacturing a multilayer flexible wiring board will be described.
[0031]
2 (a), 2 (b), 2 (c), and 2 (d) are cross-sectional views of essential parts schematically showing an embodiment of a method for manufacturing a multilayer flexible wiring board. As shown in FIG. 2 (a), first, a copper foil (9a) having a thickness of 12 μm to be a wiring pattern 9a in a later process is prepared, and a predetermined portion 0 A conductive paste is printed by positioning and arranging a metal mask having a hole having a diameter of 2 mm. After the conductive paste is dried, printing is repeated a plurality of times by using the same metal mask and printing is performed again at the same position to form a substantially conical mountain-shaped bump having a height of about 150 μm and serving as the interlayer connection conductor 10. .
[0032]
Thereafter, a 50 μm thick liquid crystal polymer film, for example, a BIAC film (trade name) or a Vexta film (trade name) having a melting point of 335 ° C. to be the first thermoplastic resin layer 8 b is provided on the side of the copper foil on which the chevron bumps are formed. ) And a copper foil (9b) having a thickness of 12 μm to be a wiring pattern 9b in a later step is laminated and integrated. Next, a contact plate is arranged on both copper foil surfaces of the laminate, and hot-pressed with a resin pressure of about 4 Mpa to produce a double-sided copper foil-laminated plate. In the hot pressing, the chevron bumps of the copper foil (9a) penetrate the first thermoplastic resin film 8b exhibiting compositional deformability, and the tip ends reach the opposing copper foil (9b) surface. In the crushed state, it is electrically connected with a resistance of 0.01Ω or less. Here, a chevron bump forming an interlayer connection conductor is formed on one surface of one copper foil (9a), but a chevron bump is formed on one surface of both copper foils (9a) and (9b) by shifting the position. By adopting a configuration in which the first thermoplastic resin film 8b is penetrated with the formed faces of the angled bumps facing each other, it is possible to form an interlayer connection conductor suitable for finer wiring.
[0033]
Both copper foils of the double-sided copper foil-bonded plate manufactured above are subjected to a photo-etching treatment, and as shown in FIG. 2A, a required wiring pattern is formed to form a wiring substrate 13 having a double-sided wiring pattern. Here, each of the wiring patterns 9a and 9b protrudes about 12 μm from the surface of the first thermoplastic resin layer 8b. Further, the interlayer connection conductor 10 connects the wiring patterns 9a and 9b.
[0034]
Next, a liquid crystal polymer film having a thickness of 25 μm, for example, a C-type film having a melting point of 325 ° C., serving as the second thermoplastic resin 11 is laminated on both surfaces of the wiring base plate 13 of the double-sided wiring pattern, and the resin pressure is set to about 3 Mpa. Heat press. That is, as shown in FIG. 2B, the entire surface of the wiring base plate 13 of the wiring pattern including the wiring patterns 9a and 9b is integrally covered with the second thermoplastic resin layer 11. Thereafter, the coated second thermoplastic resin layer 11 is subjected to a slash processing to expose the wiring patterns 9a and 9b, and as shown in FIG. Face.
[0035]
That is, the second thermoplastic resin is formed on the surface of the non-wiring pattern area adjacent to the wiring patterns 9a and 9b on both surfaces of the first thermoplastic resin layer 8b so as to form the same flat surface as the exposed surface of the wiring patterns 9a and 9b. A blank for double-sided wiring filled with the layer 11 is prepared. Here, the filling arrangement of the second thermoplastic resin layer 11 was performed by punching the wiring patterns 9a and 9b in a reverse pattern instead of performing the slash processing on the slightly thicker second thermoplastic resin film 11. A configuration in which the second thermoplastic resin film 11 is fitted and fitted may be adopted.
[0036]
Next, with the filling arrangement of the second thermoplastic resin layer 11, a 50 μm thick first thermoplastic resin layer 8a, 8c is formed on the base plate surface which is flattened with the exposed surfaces of the wiring patterns 9a, 9b. , For example, a BIAC film having a melting point of 335 ° C. is laminated. Furthermore, a copper foil (9c) is laminated on the outer side of the film to be the first thermoplastic resin layers 8a and 8c with the angled bumps formed on one side facing each other, and the resin pressure is set to about 4 Mpa. Then, as shown in FIG. 2 (d), a base plate for a multilayer wiring board with a double-sided copper foil is manufactured as shown in FIG. In the above-described pressurization, the chevron-shaped bumps penetrate the first thermoplastic resin layers 8a and 8c exhibiting composition deformability, and the tip ends thereof reach the opposed wiring patterns 9a and 9b, and are crushed. Electrically, they are connected to each other with a resistance of 0.01Ω or less.
[0037]
After that, the outer surface of the prepared multilayer wiring board base plate is subjected to perforation processing for forming mounting vias and conductive processing of the perforated part by a carbon dioxide laser or the like, if necessary, and then to the outer surface. By subjecting the copper foil (9c) to photo-etching treatment, the exterior wiring pattern 9c can be obtained, and a multilayer flexible wiring board as shown in FIG. 1 can be obtained. In this example of the manufacturing method, a thin multi-layered flexible wiring board exhibiting reliable electrical characteristics without causing a risk of peeling and damaging even after repeated bending is manufactured with high yield. be able to.
[0038]
The present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. For example, the number of built-in wiring patterns may be a three-layer type or a multilayer type having five or more layers, and a combination of the first thermoplastic resin and the second thermoplastic resin is not limited to a combination of liquid crystal polymers, A combination of a liquid crystal polymer and another thermoplastic resin may be used.
[0039]
Further, if the shape shown in FIG. 2C is formed on one side, it goes without saying that up to about 60 layers can be integrally laminated.
[0040]
【The invention's effect】
According to the present invention, a multilayer flexible wiring board in which a plurality of wiring pattern layers are built-in, and projecting conductors projecting from the wiring pattern surface penetrate the thermoplastic resin layer to electrically connect the wiring pattern layers. In this case, the thermoplastic resin layers constituting the interlayer insulator are joined and integrated via another thermoplastic resin layer having a lower melting point than the thermoplastic resin. That is, not only the structure is simplified, but also a multi-layer flexible wiring board which is thin and has a highly reliable function is provided.
[0041]
Further, by forming at least the interlayer insulator of a liquid crystal polymer, a multilayer flexible wiring board having further improved electrical characteristics is provided.
[0042]
Further, according to the manufacturing method of the present invention, not only the structure is simplified, but also a multi-layer flexible wiring board having a thin and highly reliable function can be easily provided with high yield and mass production. it can.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a main part of a multilayer flexible wiring board according to an embodiment of the present invention.
FIGS. 2A, 2B, 2C, and 2D are cross-sectional views of essential parts schematically showing an embodiment of a production example of a multilayer flexible wiring board according to the embodiment in the order of steps.
FIG. 3 is a cross-sectional view showing an example of a configuration of a main part of a conventional multilayer flexible wiring board.
FIGS. 4A, 4B, and 4C are cross-sectional views of essential parts schematically showing a conventional method for manufacturing a multilayer flexible wiring board in the order of steps.
[Explanation of symbols]
8: Interlayer insulator 8a, 8b, 8c composed of first thermoplastic resin: First thermoplastic resin layers 9a, 9b, 9c: Wiring pattern 10: Interlayer connection conductor 11: Second thermoplastic resin layer 12 : Via-type terminal

Claims (9)

A wiring pattern is formed on both main surfaces of the first thermoplastic resin layer, and an interlayer connection conductor penetrates the first thermoplastic resin layer between the wiring patterns to electrically connect the wiring pattern layers to each other. A first flexible wiring element which is filled with a second thermoplastic resin layer having a melting point lower than that of the first thermoplastic resin layer in a surface region adjacent to the wiring pattern on the at least one main surface to make a flat surface; Board and
A wiring pattern is formed on one main surface of the third thermoplastic resin layer, and a second flexible wiring base plate formed by penetrating the third thermoplastic resin layer from the wiring pattern side to the other main surface. ,
It is characterized by being laminated on at least one main surface of the first flexible wiring base plate while being in contact with the other main surface of the second flexible wiring base plate via the second thermoplastic resin layer. Multilayer flexible wiring board. A plurality of first thermoplastic resin layers are laminated to form an interlayer insulator, a plurality of wiring patterns are built in, and an interlayer connecting conductor penetrates the first thermoplastic resin layer between the wiring patterns. A multilayer flexible wiring board for electrically connecting wiring pattern layers,
A multilayer flexible wiring, wherein the laminated contact surfaces of the first thermoplastic resin layers are integrated via a second thermoplastic resin layer having a lower melting point than that of the first thermoplastic resin layer. Board. The multilayer flexible wiring board according to claim 1, wherein at least the first thermoplastic resin layer is a liquid crystal polymer. A first flexible wiring element plate having a wiring pattern of a predetermined thickness formed on at least one main surface of a first thermoplastic resin layer and having a projecting interlayer connection conductor penetrating the first thermoplastic resin layer. Covering the non-wiring region between the wiring patterns on the wiring pattern forming surface with a second thermoplastic resin layer having a lower melting point than the first thermoplastic resin layer;
Slash processing the coated second thermoplastic resin layer surface to form a wiring pattern surface and the non-wiring region on substantially the same plane;
A second flexible substrate having a wiring pattern on one main surface of a third thermoplastic resin layer and a protruding interlayer connection conductor penetrating in the thickness direction on the exposed surface of the wiring pattern of the first flexible wiring substrate; Opposing and laminating the non-wiring pattern surface of the other main surface of the wiring base plate,
A step of pressing the laminate in the laminating direction and joining and integrating the first flexible wiring base plate and the second flexible wiring base plate via a second thermoplastic resin layer;
A method for manufacturing a multilayer flexible wiring board, comprising: A first flexible wiring element plate having a wiring pattern formed on at least one main surface of the first thermoplastic resin layer to a predetermined thickness, and having a projecting interlayer connection conductor penetrating the first thermoplastic resin layer; Covering the wiring pattern forming surface with a second thermoplastic resin layer having a melting point lower than that of the first thermoplastic resin layer to a substantially uniform thickness filling the wiring pattern;
Slash processing the second thermoplastic resin layer surface on which the coating is formed to expose the wiring pattern surface on the same plane;
A conductor foil is attached to one main surface of the third thermoplastic resin layer, and a second flexible wiring base plate having a projecting interlayer connection conductor penetrating in the thickness direction is formed. Positioning and laminating the non-conductive foil bonding surface on the exposed wiring pattern surface of the first flexible wiring board;
A step of pressing the laminate in the lamination direction and joining and integrating the first flexible wiring base plate and the second flexible wiring base plate via the second thermoplastic resin layer;
Wiring patterning the conductor foil of the second flexible wiring base plate;
A method for manufacturing a multilayer flexible wiring board, comprising: A wiring pattern is formed to a predetermined thickness on both main surfaces of the first thermoplastic resin layer, and a projecting interlayer connection conductor penetrating the first thermoplastic resin layer from the wiring pattern side to the other main surface. Forming a first flexible wiring base plate, and covering the wiring pattern forming surface with a second thermoplastic resin layer having a melting point lower than that of the first thermoplastic resin layer. Flattening the second thermoplastic resin layer surface filled between the patterns,
A second flexible wiring having a wiring pattern and an interlayer connection conductor penetrating in a thickness direction on one principal surface of the first flexible wiring base plate surface flattened by filling with the second thermoplastic resin layer; A step of positioning and arranging the non-wiring pattern forming surface of the other main surface of the base plate,
Pressing the laminate in the laminating direction to integrate the first flexible wiring element and the second flexible wiring element with the second thermoplastic resin layer;
A method for manufacturing a multilayer flexible wiring board, comprising: 6. The method according to claim 4, wherein the first thermoplastic resin layer and the third thermoplastic resin layer are made of the same material. 7. The multilayer flexible wiring board according to claim 4, wherein the thickness of the thermoplastic resin layer forming the first and second flexible wiring boards is 25 to 200 [mu] m. Method. 9. The method for manufacturing a multilayer flexible wiring board according to claim 4, wherein the thermoplastic resin layer forming the first and second flexible wiring boards is a liquid crystal polymer.

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