JPH07111113A - Wiring cable of laminated wiring board and manufacture thereof - Google Patents

Abstract

PURPOSE:To suppress the edge backing of the metallic conductor of a wiring cable. CONSTITUTION:A wiring cable 100 has a structure in which a first metal layer 100a electrochemically more basic than a metallic conductor 1 is formed around the outer periphery of the metallic conductor 1 and a second metal layer 100b excellent in plastic workability and electrochemically more noble than the first metal layer 100a is formed around the outer periphery of the first metal layer 100a, with an insulating jacket 2 covering the outer periphery of the second metal layer 100b. Thus cathode corrosion resistance suppresses the edge backing caused by an etching electrolyte, so the reliability of connection between through-hole conductor layers can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric wire for laying wiring on a laminated wiring board and a method for manufacturing the same, and more particularly to a wiring which can improve reliability of electrically connecting through-hole conductor layers of the laminated wiring board. The present invention relates to an electric wire and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 7 is a sectional view of an example of a conventional electric wire for wiring of a laminated wiring board. The electric wire 300 for wiring has a structure in which a metal conductor wire 1 made of, for example, copper or a copper alloy is covered with an insulating jacket 2 made of polyimide, for example.

FIG. 8 is a sectional view of an example of a conventional laminated wiring board using the above-mentioned conventional wire 300 for wiring. This laminated wiring board 400 has wiring patterns LB and U on which wiring patterns are formed.
B is integrally bonded with the adhesive AD, and the electric wire 300 for wiring is laid at the joint. The wire for wiring 3
00, the through-hole conductor layers D1 and D2 of the through-holes T1 and T2 are electrically connected. There is also a multi-layered laminated wiring board in which a large number of wiring boards are bonded together.

[0004]

FIG. 9 shows a through hole T.
It is sectional drawing which shows the state just before forming the through-hole conductor layers D1 and D2 on the inner surface of 1 and T2. Through hole T1, T
2 is electroless copper plated to form through-hole conductor layers D1 and D
2 is formed, but as a pretreatment thereof, the through hole T1,
Lightly etch the inner surface of T2. This removes stains on the inner surfaces of the through holes T1 and T2, removes the oxide film adhering to the cross section of the wiring wire 300, and further roughens the plated surface to improve the adhesion of the electroless copper plating. This is because

However, as shown in FIG. 10, the metal conductor wire 1 of the wiring wire 300 is deeply etched by the etching electrolyte, so that the metal conductor wire 1 is through-hole T.
An edge back 30 is formed that is recessed from the inner surface of T1 and T2. Because of this edge back 30, the through-hole conductor layer and the metal conductor wire 1 formed by electroless copper plating
There is a problem in that the reliability of the electrical connection, and eventually the reliability of the electrical connection between the through-hole conductor layers D1 and D2, is reduced.

Therefore, an object of the present invention is to provide an electric wire for wiring a laminated wiring board, which can improve the reliability of electrical connection between through-hole conductor layers. Also,
It is to provide a method for manufacturing the electric wire for wiring.

[0007]

According to a first aspect of the present invention, there is provided a wiring board in which a plurality of wiring boards are integrally joined together so as to electrically connect through-hole conductor layers of the wiring board. In the electric wire for wiring of a laminated wiring board to be laid on the eye, a first metal layer having a property that is electrochemically baser than the metal conductor wire is provided between the metal conductor wire and the insulating outer coat. An electric wire for laying a laminated wiring board is provided.

According to a second aspect, the present invention provides a wire for wiring having the above-mentioned structure, which is excellent in plastic workability between the first metal layer and the insulating outer shell and is electrochemically superior to the first metal layer. Provided is an electric wire for wiring a laminated wiring board, which is provided with a second metal layer having a noble property.

According to a third aspect of the present invention, in the first aspect of the present invention, a metal which is electrochemically baser than the metal conductor wire is plated on the outer circumference of the metal conductor wire to a thickness of 0.03 μm or more and 3 μm or less.
A first metal layer plating step of forming a metal layer, and 0.5 μm or more, 10 μm or more of a metal excellent in plastic workability and electrochemically noble than the first metal layer on the outer periphery of the first metal layer.
A second metal layer plating step of forming a second metal layer by plating to the following thickness, a wire drawing step of drawing a wire to be plated that has undergone the second metal layer plating step, and a wire drawing step thereof A method for manufacturing an electric wire for wiring of a laminated wiring board, comprising a step of coating and baking an insulating outer coat on the outer periphery of a wire to be plated.

[0010]

In the electric wire for wiring of the laminated wiring board of the present invention according to the first aspect, the electrolytic solution for etching contacts the metal conductor wire and the first metal layer in the pretreatment step of the electroless plating of the through-hole conductor layer. Then, the metal conductor wire serves as a cathode, and the first metal layer having an electrochemically base property serves as an anode to form a galvanic cell system. As a result, a cathodic protection effect due to the cell effect occurs, and the occurrence of edge back of the metal conductor wire is prevented. That is, the elution of the metal conductor wire is suppressed by the elution of the first metal layer as a sacrificial electrode. Therefore, it is possible to improve the reliability of the electrical connection between the through-hole conductor layer formed by electroless plating and the metal conductor wire, and thus the reliability of the electrical connection between the through-hole conductor layers.

In the electric wire for wiring of the laminated wiring board of the present invention according to the second aspect, since the second metal layer excellent in plastic workability is applied to the outer periphery of the first metal layer, the wire drawing work is performed. In the case of applying, the relatively thin first metal layer is protected, and a wire having a small diameter can be suitably manufactured. Also, the first
By the action similar to that of the electric wire for wiring from the viewpoint, the occurrence of edge back can be prevented and the reliability of electrical connection between the through-hole conductor layers can be improved.

According to the method for producing a wire for wiring of a laminated wiring board of the present invention according to the third aspect, the wire for wiring according to the second aspect can be suitably produced. Here, the reason for plating the first metal layer to a thickness of 0.03 μm or more and 3 μm or less is that the thickness of less than 0.03 μm is not sufficient for cathodic protection, and the thickness of more than 3 μm is cathodic protection. This is because there is no difference in effect, but the plating cost rises. Further, the reason for plating the second metal layer to a thickness of 0.5 μm or more and 10 μm or less is that if the thickness is less than 0.5 μm, the second metal layer is broken and the first metal layer is exposed in the wire drawing step. In some cases, the effect of protecting the first metal layer is not sufficient, and if the thickness exceeds 10 μm, there is no difference in the effect of protecting the first metal layer in the wire drawing process, but the plating cost increases. is there. When the second metal layer is broken and the first metal layer is exposed in the wire drawing step, for example, a reaction occurs between the first metal layer of iron and the diamond of the die to form iron carbide, and This causes inconveniences such as wear and roughening of the surface of the wiring wire.

[0013]

The present invention will be described in more detail with reference to the embodiments shown in the drawings. The present invention is not limited to this. FIG. 1 is a sectional view of an embodiment of an electric wire for wiring of a laminated wiring board according to the present invention. This wire for wiring 1
00 is the first metal layer 1 made of iron on the outer periphery of the copper metal conductor wire 1.
00a is formed, a copper second metal layer 100b is formed on the outer circumference thereof, and a polyimide insulating outer cover 2 is covered on the outer circumference thereof. The metal conductor wire 1 may be made of copper alloy, for example. Moreover, you may use tin or zinc for the 1st metal layer 100a, for example. Further, for the second metal layer 100b, for example, gold, silver, or one having FCC in the crystal structure may be used.

The manufacturing process of the electric wire for wiring of the laminated wiring board of the present invention comprises an electroplating process, a wire drawing process, and an insulating outer coating and baking process. FIG. 2 is an explanatory diagram of the electroplating process. For example, a copper metal conductor wire 1 having a wire diameter of 0.9 mm is drawn from the bobbin 1a, and iron is electroplated on the outer periphery of the metal conductor wire 1 with an iron plating bath 3 to a thickness of 0.03 μm or more and 3 μm or less. 1. Form a metal layer. Next, copper is electroplated on the outer periphery of the wire 4a on which the first metal layer is formed in a copper plating bath 5 to a thickness of 0.5 μm or more and 10 μm or less to form a second metal layer. Next, the wire to be plated 4b on which the second metal layer is formed is dried by the dryer 6 to, for example, 70 ° C to 80 ° C.
It is dried at a temperature of ° C and wound on the winder 7a.

FIG. 3 is an explanatory view of the wire drawing process. The wire to be plated 4b on which the second metal layer has been formed is drawn out from the bobbin 1b, passed through the dies 10a and 10b of the wire drawing machine 8, and drawn to, for example, the wire to be plated 4c having a wire diameter of 0.09 mm, and the winding machine 7b. Roll it up. Since the second metal layer having excellent plastic workability is formed on the outermost periphery of the wire to be plated 4b, the wire drawing can be performed satisfactorily.

FIG. 4 is an explanatory diagram of the insulating coating and baking process. The drawn wire 4c is drawn from the bobbin 1c and annealed by the annealing device 11 at a temperature of 550 ° C., for example. Then, the annealed wire 4d is roller-coated with polyimide by the polyimide coating device 12, and further baked by the baking machine 15 at a temperature of, for example, 450 ° C. to form an insulating outer coat. The electric wire 100 for wiring manufactured by the above,
Take up on the winder 7c. The wire diameter of the wiring wire 100 is, for example, 0.140 mm.

The obtained wire 100 for wiring is treated with an aqueous ammonium persulfate solution (concentration: 200) as an electrolytic solution for etching.
It was immersed in g / l, temperature: 20 ° C.) for 90 seconds for etching, and the surface state was observed by a scanning electron microscope. No edge back was observed on the metal conductor wire 1.
As shown in FIG. 5, since the first metal layer 100a is electrochemically less base than the metal conductor layer 1 and the second metal layer 100b, it becomes a sacrificial electrode and elutes, and the edge back 30
This is because the metal conductor wire 1 is protected against corrosion.

As a comparative example, a copper wire having a wire diameter of 0.09 mm is used as a metal conductor wire, and a conventional electric wire for wiring 300 having a polyimide insulation coating applied and baked on the outer periphery thereof is etched under the same conditions as described above. When the surface condition was observed with a scanning electron microscope, edge back was observed in the metal conductor wire. Further, when electroless copper plating was performed to a thickness of 20 μm and the surface condition was observed with a scanning electron microscope, as shown in FIG. 10, a dent was recognized in the connection portion with the metal conductor wire 1.

[0019]

According to the wire for wiring of a laminated wiring board of the present invention, it is possible to prevent the occurrence of edge back in the metal conductor layer in the pretreatment step of the electroless plating of the through hole conductor layer, and to prevent the formation of the through hole conductor layer. The reliability of electrical connection of the metal conductor wire can be improved. Further, according to the method for producing an electric wire for wiring of a laminated wiring board of the present invention, the above electric wire for wiring can be suitably produced.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of an electric wire for wiring of a laminated wiring board according to the present invention.

FIG. 2 is an explanatory diagram of an electroplating process.

FIG. 3 is an explanatory diagram of a wire drawing process.

FIG. 4 is an explanatory diagram of an insulating outer coating and baking step.

FIG. 5 is a cross-sectional view showing a state of an edge back of an electric wire for wiring according to the present invention with an etching solution.

FIG. 6 is a cross-sectional view of a laminated wiring board on which the wiring wire of the present invention is laid.

FIG. 7 is a cross-sectional view of an example of an electric wire for wiring of a conventional laminated wiring board.

FIG. 8 is a cross-sectional view of a laminated wiring board in which a conventional wiring wire is laid.

FIG. 9 is a sectional view immediately before a pretreatment step of electroless plating of a through-hole conductor layer.

FIG. 10 is a cross-sectional view showing a state of edge backing of a conventional electric wire for wiring with an etching solution.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal conductor wire 2 Insulation skin 3 Iron plating bath 5 Copper plating bath 6 Dryer 7a, 7b, 7c Winder 8 Wire drawing machine 10a, 10b Die 11 Annealing device 12 Polyimide coating device 15 Baking machine 100 Wire for wire 100a First metal layer 100b Second metal layer 200 Laminated wiring board T1, T2 through hole D1, D2 through hole conductor layer LB, UB wiring board

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // H05K 3/10 A 7511-4E

Claims (5)

[Claims] 1. An electric wire for wiring a laminated wiring board, which is laid at a seam of a plurality of wiring boards to electrically connect through-hole conductor layers of the laminated wiring board in which a plurality of wiring boards are integrally combined. 2. An electric wire for wiring of a laminated wiring board according to claim 1, wherein a first metal layer having a property that is electrochemically baser than the metal conductor wire is provided between the metal conductor wire and the insulating jacket. 2. The electric wire for wiring of a laminated wiring board according to claim 1, wherein the plastic workability between the first metal layer and the insulating outer layer is excellent, and the electrochemical property is higher than that of the first metal layer. An electric wire for wiring a laminated wiring board, characterized in that a second metal layer having a noble property is provided on the wire. 3. The electric wire for wiring of a laminated wiring board according to claim 1, wherein the metal conductor wire is copper or a copper alloy.
An electric wire for wiring a laminated wiring board, wherein the metal layer is iron. 4. The electric wire for wiring of a laminated wiring board according to claim 2, wherein the metal conductor wire is copper or a copper alloy.
An electric wire for wiring a laminated wiring board, wherein the metal layer is iron and the second metal layer is copper, gold or silver. 5. A first metal layer plating for forming a first metal layer by plating a metal, which is electrochemically less base than the metal conductor wire, to a thickness of 0.03 μm or more and 3 μm or less on the outer periphery of the metal conductor wire. And a step of plating the outer periphery of the first metal layer with a metal having excellent plastic workability and electrochemically nobler than the first metal layer to a thickness of 0.5 μm or more and 10 μm or less.
A second metal layer plating step of forming a metal layer, a wire drawing step of drawing a wire to be plated that has undergone the second metal layer plating step, and an insulating outer coat applied to the outer periphery of the wire to be plated that has undergone the wire drawing step. A method for producing an electric wire for wiring of a laminated wiring board, comprising: an insulating outer coating and baking step.