JPH0575233A - Manufacture of wiring board - Google Patents

Abstract

PURPOSE:To prevent line discontinuity and line rising by forming a nickel layer and a copper layer on a substrate surface one by one, by oxidizing a surface of the copper layer thereafter and by forming a resist image on the surface of the copper layer wherein copper oxide is formed or by forming a resist image on a copper layer surface which is acquired by reducing copper oxide to copper. CONSTITUTION:A copper oxide layer 2 is formed on one side of a copper foil 1 by using treatment solution. An insulating base material 3 is arranged in contact with a surface of the copper foil wherein copper oxide is formed, and a lamination structure body is formed by heating and pressurizing. After a through-hole 4 is provided, the copper foil and the copper oxide layer are chemically removed. The structure body is immersed in electroless nickel plating solution and a nickel plating layer 5 is formed. A copper plating layer 6 is formed on a nickel surface using displacement copper plating solution. Thereafter, a copper oxide layer 7 is formed on a surface of the copper plating layer. The copper oxide layer 7 is immersed in reduction treatment solution and the copper oxide layer 7 is reduced to a metallic copper layer 8. A resist image 9 is formed on a surface of the metallic copper layer 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a wiring board capable of high-density wiring.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and lighter, wiring boards have been required to have a higher density of wiring, and accordingly, wiring widths, wiring intervals, or through holes have become narrower.
With such high density, deterioration of the insulation of the wiring board due to electrolytic corrosion under high humidity and high temperature electric field is becoming a problem.

That is, copper, which is the wiring material, may migrate due to ionic impurities in the insulating material under the copper wiring, and a resinous copper compound called dendrite may be generated between the wirings. The dendrite gradually grows to form a bridge, which may cause a short circuit between wirings.
As a result, the wiring interval cannot be set to 0.15 mm or less, and in order to perform high-density wiring, only the width of the wiring has to be reduced. Therefore, the wiring density is limited.

In order to suppress this dendrite, a wiring structure in which a nickel layer is formed between copper, which is a wiring metal, and an insulating substrate, or a wiring structure containing only nickel is preferable. The reason is that the nickel surface is a nickel oxide in the presence of oxygen, and this nickel oxide is more stable than a copper and copper oxide under a high humidity and high temperature environment. Therefore, even when an electric field is applied to nickel, the metal migration is less than that of copper, and it is effective in suppressing dendrite.

One of the methods for manufacturing a wiring board having a wiring structure in which a nickel layer is formed between a wiring metal, copper, and an insulating substrate is one of the methods of forming a nickel layer on the entire surface of the insulating substrate and then not forming a circuit. There is a method in which a plating resist image is formed on a portion, a copper layer is formed on a portion to be a circuit by electroplating or electroless plating, and after removing the resist, an unnecessary nickel layer is removed.

Further, as one of the methods for manufacturing a wiring board having a wiring structure having only a nickel layer, a nickel layer is formed on the entire surface of an insulating substrate, an etching resist image is formed on a portion to be a circuit, and then a circuit is formed. There is a method of etching the nickel layer in the portion that does not become. Since the nickel layer usually has high smoothness, the adhesion to the plating resist or the etching resist is low as it is, and the resist is likely to float or peel off during the resist development. In order to solve this problem, conventionally, mechanical polishing treatment was performed to form fine unevenness on the surface of the nickel layer to expand the contact area with the resist and improve the adhesiveness of the resist. ..

[0007]

However, in the surface treatment of the nickel layer, a mechanical force is applied to the nickel layer, so that the nickel layer is apt to be cracked. There is a problem that the etching liquid penetrates into the cracked portion of the nickel layer, causing line disconnection or line floating. An object of the present invention is to manufacture a wiring board free from line disconnection and line floating by forming fine irregularities on a nickel layer without performing mechanical polishing.

[0008]

According to the present invention, a nickel layer and a copper layer are sequentially formed on a substrate surface, the surface of the copper layer is oxidized to form copper oxide, and then the copper layer on which the copper oxide is formed is formed. A wiring board characterized by having a step of forming a resist image on the surface or forming a resist image on the copper layer surface obtained by reducing copper oxide to copper while maintaining the shape of copper oxide. It provides a manufacturing method. The substrate to which the present invention can be applied is a substrate made of a thermosetting resin such as an epoxy resin, a phenol resin, a polyimide resin or a polyester resin, or a thermoplastic resin such as polyethylene, a fluororesin, a polyether sulfone or a polyetherimide. Substrate, substrate made of rubber resin such as NBR, acrylic rubber, silicon rubber, polyethylene rubber, polyisoprene rubber, and the above-mentioned thermosetting resin, thermoplastic resin, rubber resin and the like, paper base material, glass cloth, glass There is a substrate made of a composite of a non-woven fabric, a non-material filler, etc., and a ceramic substrate such as Al ₂ O ₃ , AlN, SiC, SiO ₂ may be used. Alternatively, a substrate in which wiring is previously formed may be used.

The nickel layer is formed by electroless plating,
There are electroplating method, combined use of electroless plating method and electroplating method, thermal spraying method, resistance heating vapor deposition method, electron beam vapor deposition method, sputtering method, ion plating method and the like, and any of them may be used. The thickness of the nickel layer formed by such a method is preferably 0.1 μm to 20 μm.

All of the above-described metal layer forming methods can be applied to the formation of the copper layer after the formation of the nickel layer. Further, it may be a substitution plating method or a combination of the substitution plating method and the above-mentioned metal layer forming method. In such a method, the thickness of the copper layer is preferably 1 μm to 50 μm.

The method of forming copper oxide on the surface of the copper layer is usually the method used in the inner layer copper foil treatment step of a multilayer wiring board. Sodium chlorite, sodium hypochlorite, potassium persulfate, A method of immersing the substrate in a treatment liquid containing an oxidizing agent such as potassium chlorate or potassium perchlorate or a method of spraying the treatment liquid on the substrate is used. By this method, copper oxide having fine irregularities of submicron order is formed on the surface of the copper layer.

In order to manufacture a wiring board having a wiring structure in which a nickel layer is formed between copper, which is a wiring metal, and an insulating substrate, the substrate after the formation of copper oxide is treated with ammonia borane, trimethylamine borane, triethylamine borane, The copper oxide is immersed in a treatment liquid containing a reducing agent such as dimethylamine borane, sodium borohydride, and formalin, and reduced to metallic copper without changing the surface shape of the copper oxide having fine irregularities of submicron order. Then, a resist image is formed on the surface of the copper layer to form a wiring board having a nickel layer by a known method. $ For example, a resist image is formed on a part of this surface that does not become a circuit, copper is thickened on the part where there is no plating resist image by electroless plating or electroplating, and the part that does not become a circuit after peeling the plating resist The copper layer and the nickel layer are removed by etching.

Further, after forming a plating resist image on a portion of the substrate after forming copper oxide which does not form a circuit, the substrate is immersed in the above-mentioned reduction treatment solution to reduce the surface of the copper oxide layer to metallic copper, and then, Copper may be thickly plated on the surface of the metal copper. In addition, after forming a plating resist image on the part that does not become the circuit of the substrate after forming copper oxide, dip the substrate in a treatment solution containing hydrochloric acid to remove the copper oxide on the part where the plating resist image is not formed, and then this part It may be plated with copper thickly.

In order to manufacture a wiring board having a wiring structure having only a nickel layer, the substrate after the formation of the copper oxide layer is immersed in the above-mentioned reduction treatment solution to reduce the copper oxide surface to metallic copper, and then the circuit is formed. Forming an etching resist image on the
The copper layer and the nickel layer in the portion without the etching resist image are sequentially removed by etching, the resist is peeled off, and then the copper on the circuit is removed by etching.

Further, after forming an etching resist image on a portion which becomes a circuit of the substrate after the copper oxide layer is formed, copper oxide on a portion where the etching resist image is not formed is reduced to metallic copper by the above-mentioned reduction treatment liquid. , The copper layer and the nickel layer where there is no etching resist image are sequentially removed by etching, the resist is peeled off, the copper oxide is removed by dipping in a treatment solution containing hydrochloric acid, and the nickel layer is formed on the part which becomes the circuit. A copper layer may be removed by etching. Further, after forming an etching resist image in a portion which will be a circuit of the substrate after forming copper oxide, copper oxide in a portion where an etching resist image is not formed, a copper layer, and a nickel layer are sequentially removed, and after resist peeling, The copper oxide and the copper layer on the nickel forming the circuit may be sequentially removed.

[0016]

In the method for manufacturing a wiring board according to the present invention, by forming copper oxide on the copper surface formed on nickel, unevenness of submicron order is formed on the substrate surface without mechanical polishing treatment. Can be formed, line disconnection,
It is possible to manufacture a wiring board without line floating.

[0017]

Embodiments of the method for manufacturing a wiring board according to the present invention will be described below with reference to the drawings, but the present invention is not limited thereto. Example 1 FIGS. 1-1 to 1-10 of FIGS. 1 and 2 are cross-sectional views showing a manufacturing process. As shown in FIG. 1-1, a copper oxide layer 2 was formed on one surface of a copper foil 1 having a thickness of 35 μm, which is used for a normal wiring board, by using a treatment liquid having the composition shown below under the following conditions. ..

Composition NaOH 15 g / l Na ₃ PO ₄ · 12H ₂ O 30 g / l NaClO ₂ 90 g / l Pure water amount of 1 liter Condition Liquid temperature 85 ° C. Copper foil immersion time 120 seconds

After forming the copper oxide under the above conditions, as shown in FIG. 1-2, a plurality of glass cloths-epoxy prepreg E-6 are contacted with the surface of the copper foil on which the copper oxide is formed.
The insulating base material 3 made of 7 (manufactured by Hitachi Chemical Co., Ltd., trade name) is placed and heated and pressed to form a laminated structure. Then, after forming the through holes 4 at desired positions with an NC drill machine used in a normal wiring board manufacturing process, as shown in FIG. Chemically remove the copper layer. This structure was immersed in a treatment solution containing palladium chloride to attach a plating catalyst to the surface, and then the solution was added to an electroless nickel plating solution, Blue Schuma (manufactured by Kanigen Japan Co., Ltd.) solution at a plating solution temperature of 80 ° C. Immersion was performed to form the nickel plating layer 5 shown in FIGS. And
Substituted copper plating _{solution, (CuSO 4 · 5H 2 O} 2.5g /
1 and a liquid temperature of 60 ° C.), a copper plating layer 6 was formed on the nickel surface as shown in FIG. 1-5. After that, the treatment liquid used for forming the copper oxide layer 2 is used to form a copper oxide layer 7 on the surface of the copper plating layer as shown in FIG. 1-6, and subsequently, a reduction treatment liquid (NaOH 5 g / l , Dimethylamine borane 5 g / l, liquid temperature 55 ° C.) to reduce the copper oxide layer 7 to a metallic copper layer 8 as shown in FIG. 1-7. SR which is a dry film resist on the surface of the metallic copper layer 8
-3000-22 (manufactured by Hitachi Chemical Co., Ltd., trade name) was laminated, exposed and developed to form a plating resist image 9 shown in FIG. 1-8.

Then, it was immersed in an electroless copper plating solution having the following composition under the following conditions to form a patterned copper plating layer 10 shown in FIG. 1-9.

Composition CuSO ₄ .5H ₂ O 10 g / l EDTA.4Na 40 g / l 37% CH ₂ O 3 ml / l Conditions pH 12.3 Plating solution temperature 70 ° C.

After electroless copper plating, a methylene chloride solution was sprayed to remove the plating resist. Then, the unnecessary portions of the metallic copper and the copper plating layer 6 were etched using an ammonium persulfate aqueous solution (200 g / l, liquid temperature: room temperature).

Then, 40 g / l of Top Lip AZ No1 (manufactured by Okuno Seiyaku Co., Ltd.) and Top Lip AZ N
O2 (trade name, manufactured by Okuno Seiyaku Co., Ltd.) is immersed in an aqueous solution containing 500 ml / l and 30 g / l of sodium hydroxide at a liquid temperature of 90 ° C. to dissolve the nickel plating layer in unnecessary portions, and further,
Palladium, which is a plating catalyst, was removed by immersing it in an alkaline potassium permanganate solution to obtain a wiring board as shown in FIG. 1-10.

Example 2 FIGS. 2-1 to 2-10 of FIGS. 3 and 4 are cross-sectional views showing the manufacturing process. As shown in FIG. 2A, a 35 .mu.m copper foil 11 used for a normal wiring board is used. A copper oxide layer 12 was formed on one surface using a treatment liquid having the composition shown below under the treatment conditions shown below.

Composition NaOH 15 g / l Na ₃ PO ₄ · 12H ₂ O 30 g / l NaClO ₂ 90 g / l Pure water 1 l in total amount Conditions Liquid temperature 85 ° C. Copper foil immersion time 120 seconds

After forming the copper oxide under the above conditions, as shown in FIG. 2-2, a plurality of glass cloths-epoxy prepreg E- are contacted with the surface of the copper foil on which the copper oxide layer is formed.
An edge base material 13 made of 67 (manufactured by Hitachi Chemical Co., Ltd., trade name) is placed and heated and pressed to form a laminated structure. Then, after providing the through holes 14 at desired positions with an NC drill machine used in a normal wiring board manufacturing process, as shown in FIG. Copper was chemically removed. This structure is immersed in a treatment solution containing palladium chloride to attach a plating catalyst to the surface, and then immersed in a solution of Blue Schuma (trade name of Kanigen Japan Co., Ltd.) which is an electroless nickel plating solution at a liquid temperature of 80 ° C. Then, Fig. 2-4
The nickel plating layer 15 shown in was formed. Then, a substitution copper plating solution (CuSO ₄ .5H ₂ O 2.5 g / l, solution temperature 60 ° C.) was used to form a copper plating layer 16 on the nickel surface as shown in FIG. 2-5. Then, the copper oxide layer 12
As shown in FIG. 2-6, the copper oxide layer 17 is formed on the surface of the copper plating layer by using the treatment liquid used in forming the film, and subsequently the reducing treatment liquid (NaOH 5 g / l, dimethylamine borane 5 g / l) is formed. 1 and a liquid temperature of 55 ° C.) to reduce the copper oxide layer 17 to a metallic copper layer 18 as shown in FIG. 2-7.
A dry film resist PHT-145F-40 (manufactured by Hitachi Chemical Co., Ltd.) on the surface of the metal copper layer 18
Was laminated, exposed and developed to form an etching resist image 19 shown in FIG. After that, the unnecessary portions of the metal copper layer 18 and the copper plating layer 16 are etched using an ammonium persulfate aqueous solution (200 g / l, liquid temperature: room temperature) to obtain a top lip AZNo1 (Okuno Pharmaceutical, trade name).
40 g / l, Top Lip AZ No2 (manufactured by Okuno Seiyaku), 500 ml / l, sodium hydroxide 30
By immersing the nickel plating layer in an unnecessary portion by immersing it in an aqueous solution having a liquid temperature of 90 ° C. mixed with g / l, palladium as a plating catalyst is removed by an alkaline potassium permanganate solution, and then, as shown in FIG. The structure shown in FIG. Then, the etching resist was peeled off by spraying a methylene chloride solution, and the metal copper and the copper plating layer on the nickel plating layer were etched using an ammonium persulfate aqueous solution to obtain a wiring board shown in FIG. 2-10. ..

[0027]

According to the present invention, the following effects can be achieved. (1) Since resist floating and resist peeling can be reduced at the time of resist development on nickel, and line disconnection and line floating at the time of nickel etching can be reduced, it is expected to improve the manufacturing yield of wiring boards. (2) Since the substrate surface shape at the time of resist image formation is an uneven shape of the submicron order, ultraviolet rays are easily absorbed on the substrate surface, and diffused reflection of ultraviolet rays from the substrate at the time of resist exposure can be reduced, resulting in a finer pattern. A resist image can be formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining processes of 1-1 to 1-7 of Example 1 according to the present invention.

FIG. 2 is a cross-sectional view for explaining steps 1-8 to 1-10 of Example 1 according to the present invention.

FIG. 3 is a cross-sectional view for explaining a process of 2-1 to 2-7 of a second embodiment according to the present invention.

FIG. 4 is a cross-sectional view for explaining a process of 2-8 to 2-10 of the second embodiment according to the present invention.

[Explanation of symbols]

 1 Copper Foil 2 Copper Oxide Layer 3 Insulating Base Material 4 Through Hole 5 Nickel Plating Layer 6 Copper Plating Layer 7 Copper Oxide Layer 8 Metal Copper Layer 9 Plating Resist Image 10 Pattern Copper Plating Layer 11 Copper Foil 12 Copper Oxide Layer 13 Insulating Base Material 14 Through Hole 15 Nickel Plating Layer 16 Copper Plating Layer 17 Copper Oxide Layer 18 Metallic Copper Layer 19 Etching Resist Image

Front page continuation (72) Inventor Shuichi Hatakeyama 1500 Ogawa, Shimodate, Ibaraki Pref., Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Inventor, Kazuhisa Otsuka 1500 Ogawa, Shimodate, Ibaraki Hitachi Chemical Co., Ltd.

Claims (1)

[Claims] 1. A nickel layer and a copper layer are sequentially formed on a substrate surface, the surface of the copper layer is oxidized to form copper oxide, and then a resist image is formed on the copper layer surface on which the copper oxide is formed. Alternatively, a method of manufacturing a wiring board, comprising a step of forming a resist image on the surface of a copper layer obtained by reducing copper oxide to copper while maintaining the shape of copper oxide.