JP2009266957A - Wiring board, and method for manufacturing thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board capable of keeping high insulation reliability even when an inter-wiring distance is narrowed, forming the wiring of a high aspect ratio and thinning an insulating coating film as well, and to provide a method for manufacturing thereof. <P>SOLUTION: A resin substrate 1A is clamped between a pair of molding dies facing each other, and a first recessed groove recessed from the front surface side and a second recessed groove recessed from the back surface side are simultaneously molded on the resin substrate 1A by die clamping. After imparting a conductive material layer to the groove bottom of the molded first recessed groove and second recessed groove, metal wiring lines 6 and 6 are formed inside the first recessed groove and the second recessed groove by electrolytic plating or the like. Thus, the metal wiring lines 6 of the high aspect ratio are formed. Both of the front surface side and back surface side of the resin substrate 1A where the metal wiring lines 6 are formed are covered with the insulating coating film 7 to attain the wiring board A. The molded resin substrate 1A is interposed between the adjacent metal wiring lines 6 and 6, and the insulation reliability is not lowered even when a wiring density is increased. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wiring board and a manufacturing method thereof, and more particularly to a wiring board in which a resin substrate on which metal wiring is formed is covered with an insulating coating film and a manufacturing method thereof.

A wiring board having a shape in which a metal wiring is formed on a resin board and is entirely covered with an insulating coating film is known. Wire harnesses and flat cables, which are examples of such wiring boards, are used for electrical connections such as automobiles and mobile phones. Widely used in the department. Patent Document 1 describes an example of such a wiring board and a manufacturing method thereof, and after selectively removing (etching) the copper foil from the material in which the copper foil is bonded to both surfaces of the polymer film, Both sides are covered with an insulating coating film to form a wiring board. Patent Document 2 describes a method of manufacturing a wiring substrate by transfer, in which a wiring pattern is formed in a convex shape on a carrier by etching, and the wiring pattern on the carrier is formed on a resin substrate. Is transferred by heat and pressure.
JP-A-5-136575 JP 2002-204049 A

  As described in Patent Document 1, the method of forming a metal wiring by removing excess copper foil by etching is difficult to prevent the wiring from spreading out, and increases the insulation reliability between the wirings. In order to ensure, it is necessary to make the distance between wiring long, and it is not easy to form fine wiring. Etching is isotropic, and it is difficult to form a wiring with an aspect ratio of 1 or more. When a wiring with a large film thickness is required, the width of the recess is inevitably increased. Therefore, miniaturization and high density of wiring become difficult. Moreover, it is inevitable that the number of processing steps increases and the cost increases. Furthermore, it is a shape in which the wiring protrudes on the resin substrate, and if the insulating coating film is thinned, the wiring edge portion is exposed due to wear, so it is required to increase the thickness of the insulating coating film. .

  In the method described in Patent Document 2, a wiring pattern is formed in a convex shape on a carrier, and is transferred by heat and pressure onto a resin substrate, and a high aspect ratio wiring is formed on the resin substrate. However, the process of forming the wiring pattern on the carrier in a convex shape is based on an etching process. Again, it is necessary to increase the distance between the wirings in order to ensure the insulation reliability between the wirings. It becomes.

  The present invention has been made in view of the disadvantages of the prior art as described above. More specifically, the present invention can maintain high insulation reliability even when the distance between wirings is narrowed, and has a high aspect ratio. It is an object of the present invention to disclose a method of manufacturing a wiring board and a wiring board that can form a wiring and can also have a thin insulating coating film.

  A method of manufacturing a wiring board according to the present invention is a method of manufacturing a wiring board in which a resin substrate on which metal wiring is formed is covered with an insulating coating film, wherein the resin is interposed between a pair of opposing molds. Sandwiching the substrate and simultaneously forming a first groove recessed from the front surface side and a second groove recessed from the back surface side of the resin substrate; and the formed first groove and second groove A step of providing a conductive material layer on the groove bottom of the groove, a step of forming a metal wiring in the first concave groove and the second concave groove using the conductive material layer as a base material, and the metal wiring is formed. And a step of coating both the front surface side and the back surface side of the resin substrate with an insulating coating film.

  In the method for manufacturing a wiring board according to the present invention, the resin substrate is sandwiched between a pair of opposing molds and the mold is clamped, so that the resin substrate is recessed from the front surface side and the first groove groove recessed from the front surface side. The second groove is simultaneously formed on the front and back surfaces. Then, metal wiring is formed in the formed first and second grooves. In this manufacturing method, the molded resin substrate is located between adjacent wirings, and high insulation between the wirings can be ensured. For this reason, the wiring can be miniaturized and the density can be increased. Further, the groove depths of the first groove and the second groove to be molded depend on the convex portions formed along the wiring pattern on the molding surface of the mold, and any aspect ratio (groove) A first groove and a second groove having a ratio of groove depth to width) can be easily formed. Furthermore, in the state where the metal wiring is formed in the first groove and the second groove, both the front surface side and the back surface side of the resin substrate are flat surfaces. Even if both are covered with a thin insulating coating film, the metal wiring can be sufficiently protected and wiring short-circuit due to friction can be prevented.

  In a preferred aspect of the method for manufacturing a wiring board according to the present invention, the step of applying a conductive material layer to the groove bottoms of the first and second concave grooves is performed by the first concave in the pair of opposing molds. In the step of applying a conductive material layer to the surface of the convex portion corresponding to the groove and the second concave groove, and simultaneously forming the first concave groove and the second concave groove on the resin substrate, the conductive material layer Is transferred to the groove bottoms of the first groove and the second groove.

  In this aspect, the step of simultaneously forming the first groove and the second groove on the resin substrate, the step of applying a conductive material layer to the groove bottoms of the formed first groove and the second groove, Can be performed in one step, and the manufacturing process can be simplified. Of course, a step of applying the conductive material layer in a separate step may be performed after the first concave groove and the second concave groove are simultaneously formed.

  In a preferred aspect of the method for manufacturing a wiring board according to the present invention, the step of forming a metal wiring using the conductive material layer as a base material in the first and second grooves is an electroless plating process or an electrolytic plating process. The treatment can be carried out by depositing a metal layer with the conductive material layer as a nucleus. When the electroplating process is performed, the transferred conductive material layer functions as a seed layer. When electroless plating is performed, the transferred conductive material layer functions as a plating catalyst nucleus.

  In the method for manufacturing a wiring board according to the present invention, the material for forming the conductive material layer is not limited, but a metal paste in which inorganic metal particles and a solvent are mixed or a resinate paste in which an organic metal compound and a solvent are mixed is used. be able to. The metal paste is not limited, but a copper paste which is a low resistance material is particularly preferable. In addition, silver paste, gold paste, nickel paste, or the like can also be used. In that case, the particle size of the metal particles is preferably about several nm to several hundred nm. Resin pastes include copper resinates, silver resinates, gold resinates or nickel resinates. In the case of a metal paste, by performing transfer by hot pressing during molding of the resin substrate, the sintering process of the metal particles proceeds to become a metal film, and a part thereof is embedded on the resin substrate side. Thereby, the transfer of the metal film to the resin substrate side also proceeds reliably. The sintering temperature is selected depending on the material on the resin substrate side, but is preferably 100 to 500 ° C.

  In the method for manufacturing a wiring board according to the present invention, as a mold material, a convex portion along the wiring pattern can be molded, and resistance to mechanical and thermal stress when transferring to the resin board side is provided. Any material can be used on the condition, but materials such as glass, silicon, quartz, stainless steel, resin, and metal can be preferably used. Examples of the metal material include nickel (alloy) and stainless steel, and nickel (alloy) is particularly preferable from the viewpoint of durability and positional accuracy.

  In order to form the convex portion according to the wiring pattern on the surface of the mold, a conventionally known technique such as a microetching method, an electroforming method, or a microcontact printing method can be used. Use an appropriate method according to the material used. Among them, the micro contact printing method is preferable.

  The width and height of the first and second grooves formed on the resin substrate, that is, the width and height of the protrusions formed on the molding surfaces of the pair of molds, the distance between the protrusions, etc. Although it sets according to the wiring pattern calculated | required by the wiring board to obtain, as an example, the width | variety of a convex part is about 5 micrometers-300 micrometers, and height is about 5 micrometers-about 500 micrometers. The width and height of the convex portions may all be the same or may be partially different.

  In the method for manufacturing a wiring board according to the present invention, the material of the resin substrate is arbitrary on the condition that it is a non-conductive material, and materials conventionally used in this type of wiring board can be appropriately used. It is more preferable that the film has a thickness of about 10 μm to 100 μm. From the viewpoint of ease of molding, shape retention of the first and second grooves formed after the molding, thermoplastic resin or thermosetting resin is particularly preferable. Resin, polystyrene resin, polyethylene resin, polyacrylonitrile, vinyl chloride, polycarbonate, polyethylene terephthalate, polytetrafluoroethylene, polyether ether ketone, polyethylene naphthalate, polyimide resin, polyamic acid resin that is a precursor of polyimide, etc. It is done. Of these, polyimide resins having high thermal, mechanical, and chemical properties are preferable.

  In the method for manufacturing a wiring board according to the present invention, the insulating coating film is optional on the condition that it is a non-conductive material like the material of the resin substrate. Can be used as appropriate. It is more preferable that the film has a thickness of about 10 μm to 100 μm. More specifically, examples of the resin include polyvinyl chloride, polyimide, and polyethylene terephthalate. Among these, polyvinyl chloride is preferable from the viewpoints of flexibility, moisture resistance, electrical insulation, and cost.

  The present invention further relates to a wiring board formed by the above-described manufacturing method, in which a resin board on which metal wiring is formed is covered with an insulating coating film, and the resin board is recessed from the surface side. A first groove and a second groove recessed from the back surface side are formed, and the metal wiring is formed in both the first groove and the second groove, and the insulating property Also disclosed is a wiring board characterized in that the coating film covers both the front surface side and the back surface side of the resin substrate on which the metal wiring is formed.

  As described in the above manufacturing method, the wiring board according to the present invention enables miniaturization and high density of the wiring, and can form a wiring with a high aspect ratio. Even if both sides of the back side are covered with a thin insulating coating film, wiring short-circuit due to friction can be prevented. Further, since the wiring shape can be a pair of top and bottom, disconnection due to curling or stress uneven distribution of the resin substrate or the insulating coating film can be prevented.

  In a preferred aspect of the wiring board according to the present invention, a plurality of the first concave grooves and the second concave grooves are formed in parallel and alternately on the resin substrate. Preferably, the aspect ratios of the metal wirings formed in the first groove and the second groove are all equal. The wiring board of this form is particularly suitable as a wire harness or a flat cable used for an electrical connection part of an automobile or a mobile phone.

  In the wiring board according to the present invention, although not limited, the width of the metal wiring is about 5 μm to 300 μm and the height is about 5 μm to 500 μm. The wiring board is preferably a resin film, and the thickness is not limited, but is about 10 μm to 100 μm. The insulating coating film is also preferably a resin film and has a thickness of about 10 μm to 100 μm. Those materials and the like are as described in the description of the manufacturing method.

  According to the present invention, high insulation reliability can be maintained even when the distance between wirings is narrowed, wiring with a high aspect ratio can be formed, and the insulating coating film can be thin. A wiring board that can be obtained can be obtained by a simpler process.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings. 1 to 3 show a first step of forming a first concave groove recessed from the front surface side and a second concave groove recessed from the rear surface side in the resin substrate in the method for manufacturing a wiring board according to the present invention. FIG. 4 to FIG. 6 are diagrams for explaining a second form of the process. FIG. 7 shows a resin substrate on which metal wiring is formed, and FIG. 8 shows a wiring substrate according to the present invention.

  In FIG. 1, reference numeral 1 denotes a resin substrate, and in this example, a polyimide film having a thickness of about 100 μm. Reference numerals 10 and 20 denote a pair of opposing molds. In this example, both are nickel alloy plates. In the figure, on the molding surface side (lower surface side) of the upper mold 10, a long shape corresponding to the wiring pattern formed on the surface side of the wiring board to be obtained by electroforming processing known in the art or the like. A plurality of projections 11 (four in the figure) are formed in parallel to each other. In this example, the cross-sectional dimensions of the protrusions 11 are all equal, the width a is 200 μm, and the height b is 500 μm. Further, the intervals c between the adjacent convex portions 11 are all equal, and c = 200 μm + 2 × 75 μm.

  Also on the molding surface side (upper surface side) of the lower molding die 20, a long convex portion corresponding to the wiring pattern formed on the back surface side of the wiring substrate to be obtained by a conventionally known electroforming process or the like A plurality of 21 (three in the figure) are formed in parallel to each other. In this example, the cross-sectional dimensions of the convex portions 21 are all equal, the width a is 200 μm, the height b is 500 μm, and the intervals c between the adjacent convex portions 21 are all equal, c = 200 μm + 2 × 75 μm. In the figure, reference numeral 22 denotes an outer frame of the mold 20, and its height is higher by 75 μm than the height of the convex portion 21.

  The molding surface sides of the upper and lower molds 10 and 20 are made to face each other as shown in FIG. 1 so that the convex portions 11 of the molding die 10 are positioned between the convex portions 21 and 21 of the molding die 20, A resin substrate 1 having a required size is placed between the upper and lower molds 10 and 20. The molds 10 and 20 are heated to about 400 ° C., and the upper and lower molds 10 and 20 are clamped. The state after mold clamping is shown in FIG. By clamping the mold under heating and pressure welding, the resin substrate 1 which is a polyimide film having a thickness of about 100 μm is formed into an uneven molding space (cavity) having a thickness of 75 μm formed between the opposing molds 10 and 20. In a corresponding manner, a shape that is bent is applied.

  After maintaining the state for a predetermined time, for example, about 20 minutes, the temperature is returned to normal temperature and pressure, and the mold is opened. As a result, as shown in FIG. 3, the four first concave grooves 2 that are recessed from the front surface side toward the rear surface side, and the first concave grooves 2 and 2, from the rear surface side toward the front surface side. A resin substrate 1A is obtained in which three recessed second recessed grooves 3 are formed at the same time. The resin thickness d in the resin substrate 1A after molding is 75 μm, and the cross-sectional shapes of the first concave groove 2 and the second concave groove 3 are all equal.

  Next, for example, copper paste 4 is applied to the groove bottoms of the first and second concave grooves 2 and 3 in the molded resin substrate 1A shown in FIG. , 20 is clamped again in a temperature range in which the resin shape is not deformed, for example, about 300 ° C., and a conductive material layer 5 which is a copper thin film is formed at the groove bottom as shown in FIG. The copper paste 4 may be simply applied, but by heating and pressing the copper paste 4 to embed a part of the copper component in the resin substrate 1A, the resin substrate 1A and the conductive material layer 5 which is a copper thin film It is possible to ensure a high adhesive strength between the two.

  4 to 6, the resin substrate 1 and the upper and lower molds 10 and 20 used are the same as those shown in FIG. In this example, when the molds 10 and 20 are clamped, for example, copper nano-particles having an average particle diameter of 10 nm are provided at the tips of the protrusions 11 of the mold 10 and the tips of the protrusions 21 of the mold 20, respectively. A copper paste 4 mainly composed of particles is applied to a thickness of about 2 μm. In this state, the mold clamping is performed as shown in FIG. 5 in the same manner as described with reference to FIG. Thereby, the copper paste 4 is transferred to the groove bottoms of the first and second concave grooves 2 and 3 of the molded resin substrate 1A, and in the process, the copper nanoparticles in the copper paste are baked. As a result, the conductive material layer 5 of a continuous copper thin film is formed. Further, a part of the resin substrate 1 is embedded by pressure contact by clamping, and a high adhesive force between the resin substrate 1A and the conductive material layer 5 that is a copper thin film can be secured. Furthermore, when the mold clamping is performed in a vacuum environment, the detachment of the solvent from the copper paste 4 is also promoted.

  Open the mold after normal temperature and normal pressure. Accordingly, the four first concave grooves 2 that are recessed from the front surface side toward the rear surface side and the first concave grooves 2 and 2 in the form shown in FIG. The three second concave grooves 3 that are recessed are simultaneously formed, and a conductive material layer 5 that is a copper thin film is formed by transfer on the groove bottoms of the first concave groove 2 and the second concave groove 3. The obtained resin substrate 1A is obtained. The resin thickness d in the molded resin substrate 1A is approximately 75 μm, and the cross-sectional shapes of the first concave groove 2 and the second concave groove 3 are all equal.

  Next, the molded resin substrate 1A having the shape shown in FIG. 6 is immersed in, for example, a copper sulfate plating bath, and electrolytic plating is performed for about 20 minutes. In the process, copper ions in the plating bath are deposited in the first concave groove 2 and the second concave section 3 with the conductive material layer 5 as a nucleus, and as shown in FIG. A desired copper wiring 6 is filled in the second and second recesses 3. Then, by removing the metal protruding from the first concave groove 2 and the second concave portion 3 by polishing, the front and back surfaces of the molded resin substrate 1A on which the copper wiring 6 is formed become flat surfaces.

  Finally, for example, a polyvinyl chloride film having a thickness of about 30 μm is used as the insulating coating films 7, 7, as shown in FIG. 8, as shown in FIG. Thus, the wiring board A according to the present invention is completed.

  As shown in FIG. 8, in the wiring board A according to the present invention, the resin substrate 1A after molding is positioned between the adjacent metal wirings 6 and 6, and high insulation between the wirings is ensured. For this reason, the wiring can be miniaturized and the density can be increased. Moreover, the groove depth of the 1st groove | channel 2 and the 2nd groove | channel 3 which are shape | molded depends on the convex parts 11 and 21 formed along a wiring pattern in the shaping | molding surface of the shaping | molding die 10 and 20. FIG. Therefore, the metal wiring 6 having an arbitrary aspect ratio can be easily formed. Further, in the state where the metal wiring 6 is formed in the first and second concave grooves 2 and 3, both the front surface side and the rear surface side of the resin substrate 1A are flat surfaces. Even if both the front surface side and the back surface side of 1A are covered with the thin insulating coating films 7 and 7, it is possible to effectively avoid a short circuit between wirings due to friction. Further, since the wiring shape can be a pair of upper and lower shapes, it is possible to avoid the occurrence of curling or stress unevenness in the molded resin substrate 1A or the insulating coating films 7 and 7, resulting in curling or stress unevenness. Thus, the disconnection can be effectively prevented.

  In the manufacturing method according to the present invention, the metal wiring can also be formed by performing electroless plating treatment instead of electrolytic plating treatment. Even in the case of electroless plating, the conductive material layer may be the same as that in the case of electrolytic plating.

  Although not shown, as a method of continuously forming the first concave groove 2 and the second concave groove 3 on the belt-shaped resin substrate, a method of passing between a pair of rolls formed with concave and convex grooves meshing with each other on the peripheral surface is used. It can also be used. By passing between the pair of rolls in a heating environment, the first concave groove 2 that is recessed from the front surface side and the second concave groove 3 that is recessed from the back surface side are simultaneously and continuously formed in the belt-shaped resin substrate. Can be molded. Further, in the illustrated example, the aspect ratio of all the metal wirings 7 has been described as being equal, but the cross-sectional shape of the convex portion in each mold, or the concave and convex grooves in the roll having the concave and convex grooves on the peripheral surface described above. By changing the cross-sectional shape, a wiring board having metal wirings with different aspect ratios on the front and back surfaces can be manufactured. Further, in the manufacturing method using the pair of upper and lower molds 10 and 20, the first concave groove 2 and the second concave groove 3 are not linear ones parallel to each other, but the first according to an appropriate wiring pattern. The groove 2 and the second groove 3 can be formed in a pair of upper and lower shapes.

The figure explaining one Embodiment of the manufacturing method of the wiring board by this invention. The figure explaining the state clamped in the manufacturing method shown in FIG. The figure explaining the resin substrate after the shaping | molding obtained with the manufacturing method shown in FIG. The figure explaining other embodiment of the manufacturing method of the wiring board by this invention. The figure explaining the state clamped in the manufacturing method shown in FIG. The figure explaining the resin substrate after shaping | molding which has a conductive material layer in a groove bottom. Sectional drawing explaining the resin substrate after metal wiring formation. Sectional drawing explaining the wiring board by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS A ... Wiring board, 1 ... Resin board | substrate, 1A ... Resin board | substrate after shaping | molding, 10 ... Upper mold, 11 ... Convex part, 20 ... Lower mold | die, 21 ... Convex part, 22 ... Outer frame of a shaping | molding die, DESCRIPTION OF SYMBOLS 2 ... 1st ditch | groove, 3 ... 2nd ditch | groove, 4 ... Copper paste, 5 ... Conductive material layer which is a copper thin film, 6 ... Metal (copper) wiring, 7 ... Insulating coating film

Claims (8)

A method of manufacturing a wiring board in which a resin substrate on which metal wiring is formed is covered with an insulating coating film,
Sandwiching the resin substrate between a pair of opposing molds, and simultaneously molding a first groove recessed from the front surface side and a second groove recessed from the back surface side of the resin substrate;
Applying a conductive material layer to the groove bottoms of the molded first and second grooves,
Forming a metal wiring using the conductive material layer as a base material in the first and second grooves,
A step of covering both the front side and the back side of the resin substrate on which the metal wiring is formed with an insulating coating film;
A method of manufacturing a wiring board, comprising:   2. The method of manufacturing a wiring board according to claim 1, wherein the step of applying a conductive material layer to the groove bottoms of the first and second concave grooves is performed in the first pair of molds facing each other. In the step of applying a conductive material layer to the surface of the convex portion corresponding to the concave groove and the second concave groove, and simultaneously molding the first concave groove and the second concave groove on the resin substrate, A method of manufacturing a wiring board, comprising: transferring a material layer to groove bottoms of the first and second grooves.   3. The method of manufacturing a wiring board according to claim 1, wherein the step of forming a metal wiring using the conductive material layer as a base material in the first groove and the second groove is an electroless plating. A method of manufacturing a wiring board, comprising: depositing a metal layer with the conductive material layer as a nucleus by a treatment or an electrolytic plating treatment.   The method for manufacturing a wiring board according to claim 1, wherein a metal paste or a resinate paste is used as a material for forming the conductive material layer.   2. The method for manufacturing a wiring board according to claim 1, wherein any one of glass, silicon, quartz, stainless steel, resin, and metal is used as a material of the mold.   A wiring board in which a resin board on which metal wiring is formed is covered with an insulating coating film, wherein the resin board has a first groove recessed from the front surface side and a second groove recessed from the back surface side. A groove is formed, the metal wiring is formed in both the first concave groove and the second concave groove, and the insulating coating film is a surface of the resin substrate on which the metal wiring is formed. A wiring board characterized by covering both the side and the back side.   7. The wiring board according to claim 6, wherein a plurality of the first concave grooves and the second concave grooves are formed in parallel and alternately on the resin substrate. .   The wiring board according to claim 6, wherein the aspect ratios of the metal wirings formed in the first concave groove and the second concave groove are all equal.

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