JP4507780B2 - Manufacturing method of printed wiring board with built-in resistor - Google Patents

Description

  The present invention relates to a method of manufacturing a printed wiring board with a built-in resistor, and in particular, a material that can be easily etched by an etching solution for a wiring layer can be used for the resistor layer, and an insulating resin is laminated on the resistor. The present invention relates to a method for manufacturing a resistor-embedded printed wiring board that is not affected by the surface roughening treatment liquid that is required before.

  In recent years, as devices such as mobile phones and digital cameras have become smaller and lighter, conventional mounting technologies such as miniaturization of parts and reduction of the interval between parts have become difficult to cope with. Expectations are rising. Passive elements (capacitors, resistors, inductors) can satisfy the characteristics required by equipment manufacturers relatively easily by embedding existing parts, but there is a problem that the board containing the parts becomes thick. There is an urgent need to develop a method that can sufficiently satisfy characteristics with thin parts and thin film elements.

  As a method of forming a resistor inside a printed wiring board, a method of forming a resistance layer with a metal thin film on a copper foil, a method of forming by plating on an insulating substrate, a method of printing a resistive thick film polymer, etc. There is. It is necessary to select a forming method according to the application from the resistance value, accuracy, shape, price, and the like. In the method of printing a thick film polymer, it is possible to form a high-resistance material, but it is difficult to form a fine size. The thin film type using a metal material is restricted to a low resistance range as compared with the thick film type, but can be formed with a small size and high accuracy.

  As a material in which a resistance layer is formed of a metal thin film on a copper foil, there is a method of using a material in which a thin film resistance layer formed on a copper foil is laminated on an insulating material. Omega Technologies' Omega-Ply is a material in which the thin film resistance layer is formed by electrolytic nickel / phosphorus plating (see, for example, Patent Document 1). In the case of using such a material, the copper foil and the thin film resistance layer are collectively etched to form a wiring, a predetermined wiring portion is etched, and the lower resistance layer is exposed to form a resistor. When etching a predetermined wiring portion, it is necessary to etch only copper without using a special etchant to etch nickel, but there is a problem that nickel is etched. Omega-Ply has a sheet resistance of 25 to 100Ω / □, but a higher sheet resistance is required.

As a method for preventing etching of the resistance layer when a predetermined wiring portion is etched, for example, there is a method described in Patent Document 2. This is a method in which a protective layer is provided on the resistance layer in close contact with the support layer, the resistance layer is protected from attack by the alkaline ammonia copper etching solution, and the protective layer is not removed by etching but remains as a part of the resistance layer. . In this method, it is necessary to form the protective layer as thin as possible so that the resistance value of the protective layer does not affect the resistance value of the resistor. Further, as a protective layer, Ni—Sn, Co—Sn, Cd—Sn, Cu—Ni, Ni—Cr, Ni—Au, Ni—Pd, Ni—Zn, Sn—Pb, Sn—Zn, Ni and Sn are used. Since a material selected from the group is used, there is a problem that the conduction resistance of the wiring increases. Therefore, it has been demanded to form a protective layer that protects the resistor during the formation of the resistor and is removed after the formation.
US Pat. No. 4,808,967 Japanese National Patent Publication No. 9-500762

  The present invention has been made in view of the above circumstances, and in a resistor-embedded printed wiring board, a material that can be easily etched by an etching solution for a wiring layer can be used for the resistor layer, and is necessary before laminating an insulating resin on the resistor. An object of the present invention is to provide a method for manufacturing a resistor-embedded printed wiring board that is not affected by the surface roughening solution.

The present invention has been made in view of the above-described problems, and the invention of claim 1 is directed to a method of manufacturing a resistor-embedded printed wiring board.
(A) a step of forming a resistance layer on the insulating substrate by plating;
(B) forming a protective layer on the resistive layer;
(C) forming a wiring layer on the protective layer;
(D) forming an etching resist on the wiring layer;
(E) forming a wiring pattern comprising the wiring layer, the protective layer, and the resistance layer by etching the wiring layer, the protective layer, and the resistance layer, and then removing the etching resist;
(F) forming an etching resist on the wiring pattern;
(G) a step of etching a predetermined wiring layer to expose a lower protective layer;
(H) removing the etching resist and roughening the surface of the wiring layer;
(I) forming a resistor by etching the exposed protective layer;
(J) laminating an insulating resin on the resistance layer to form an insulating layer;
(K) forming a via and forming a wiring layer on the insulating layer at the same time as making the resistor conductive;
(L) a step of patterning the wiring layer;
Equipped with,
The material for forming the protective layer is gold, which is a method for manufacturing a printed wiring board with a built-in resistor.

  According to a second aspect of the present invention, the resistive material forming the resistive layer is a material made of a nickel-phosphorus binary alloy or a nickel-phosphorus ternary alloy. It is a manufacturing method of the printed wiring board with a built-in resistor.

According to a third aspect of the present invention, in the step (e), after the wiring layer is etched, the protective layer and the resistance layer are shaved by sand blasting or wet blasting, so that the wiring layer, the protective layer, and a method for producing a resistor embedded printed circuit board of claim 1 or 2, characterized in that to form a wiring pattern composed of the resistive layer.

The present invention is a method of manufacturing a printed wiring board with a built-in resistor, after forming a protective layer of a resistive layer, forming a wiring layer, etching a predetermined wiring layer, and finally etching away the protective layer, Since the resistance layer can be prevented from being etched, a material made of a nickel-phosphorus ternary alloy that is easily etched by the wiring layer etchant can be used for the resistance layer. In general, a material made of a nickel / phosphorus ternary alloy has a higher resistance than a material made of a nickel / phosphorus ternary alloy, so that a high-resistance resistor can be formed.
Further, in order to remove the protective layer after the surface roughening treatment of the wiring layer, the resistor is protected from the surface roughening treatment liquid used for the surface roughening treatment required before laminating the insulating resin on the resistor. Therefore, the resistor can be formed with high accuracy.
In addition, since gold is used for the protective layer, the conduction resistance of the wiring can be reduced. Therefore, in the method for manufacturing a printed wiring board with a built-in resistor, there is an effect that a resistor having a higher resistance than before can be manufactured without changing the resistance value.

  The method of manufacturing a printed wiring board according to claim 1 is a method of manufacturing a resistor-embedded printed wiring board by a process comprising steps (a) to (l) in the following order. 1A to 1J are cross-sectional views illustrating the steps of the manufacturing method.

  First, (a) the resistance layer 2 is formed on the insulating substrate 1 by plating. Plating is performed by electroless plating, and plating is performed using a plating solution that satisfies a predetermined volume resistivity so as to have a predetermined sheet resistance value (see FIG. 1A).

  The insulating substrate 1 that can be used in the present invention is not particularly limited, and may be a plate made of various synthetic resins, a flexible sheet, a glass plate, a ceramic plate, or a metal substrate having an insulating layer on the surface. Therefore, it can be appropriately selected and used depending on the application.

  In the present invention, the resistive material used as the resistance layer 2 is made of a nickel / phosphorus binary alloy or a nickel / phosphorus ternary alloy. For example, the resistance layer 2 is formed by electroless plating of nickel / phosphorus, nickel / phosphorus / iron, nickel / phosphorus / tungsten, nickel / phosphorus / molybdenum, nickel / phosphorus / rhenium, nickel / phosphorus / chromium. In order to stably form a high-resistance resistor, a plating solution having a high volume resistivity and a slow plating deposition rate is preferable. Further, the resistance value and the plating deposition rate can be adjusted by adjusting the P concentration, complexing agent concentration, reducing agent concentration, temperature and pH of the plating solution. Since the present invention is a method for preventing the resistance layer 2 from being etched when the predetermined wiring layer 4 is etched, a material made of a nickel-phosphorus ternary alloy having a large etching amount with the etching solution of the wiring layer 4 is used as the resistance layer. 2 can be used. In general, a material made of a nickel / phosphorus ternary alloy has a higher resistance than a material made of a nickel / phosphorus ternary alloy, so that the resistor 7 having a high resistance can be formed.

  Next, (b) a protective layer 3 is formed on the resistance layer 2. As a material for forming the protective layer 3, a material that does not affect the resistance value even if left in between, gold, a material that is not etched with a liquid that etches the wiring layer 4, or an etching of the wiring layer 4 and the resistance layer 2 is performed. It is assumed that the material is etched with a liquid that does not (see FIG. 1B).

  Next, (c) a wiring layer 4 is formed on the protective layer 3 (see FIG. 1C). The material for forming the wiring layer 4 is preferably a metal material with good conductivity such as gold, silver, copper, nickel, and aluminum.

  Next, (d) an etching resist 5 is formed on the wiring layer 4 (see FIG. 1D).

  Next, (e) the wiring layer 4, the protective layer 3, and the resistance layer 2 are etched, and then the etching resist 5 is removed to form a wiring pattern 6 including the wiring layer 4, the protective layer 3, and the resistance layer 2. . In this etching, the wiring layer 4, the protective layer 3, and the resistance layer 2 are all etched together using a solution that can be etched, or the wiring layer 4, the protective layer 3, and the resistance layer 2 are respectively used using different solutions. There is a method of etching. In the latter case, when the protective layer 3 is etched, an etching solution that is difficult to etch the wiring layer 4 is used, and when the resistance layer 2 is etched, an etching solution that is difficult to etch the wiring layer 4 and the protective layer 3 is used. It is desirable to use it (see FIG. 1E).

  In this step (e), after the wiring layer 4 is etched, the protective layer 3 and the resistance layer 2 are cut by sand blasting or wet blasting to form a wiring pattern 6 composed of the wiring layer 4, the protective layer 3 and the resistance layer 2. You can also

  Next, (f) an etching resist is formed on the wiring pattern 6.

  Next, (g) the predetermined wiring layer 4 is etched to expose the lower protective layer 3. When the wiring layer 4 is etched, a liquid that does not etch the protective layer 3 is used (see FIG. 1F).

  Next, (h) the etching resist is removed, and the wiring layer 4 is subjected to a surface roughening treatment. In order to protect the resistance layer 2 from the surface roughening treatment, the surface roughening treatment of the wiring layer 4 is performed with the protective layer 3 exposed.

  Next, (i) the exposed protective layer 3 is etched to form the resistor 7. When the protective layer 3 is etched, a solution that does not etch the wiring layer 4 and the resistor 2 is used (see FIG. 1G).

  Next, (j) an insulating resin is laminated on the resistor 7 to form the insulating layer 8 (see FIG. 1H).

  Next, (k) a via is formed to make the resistor 7 conductive, and at the same time, a wiring layer 9 is formed on the insulating layer 8 (see FIG. 1I).

  Next, (l) the wiring layer 9 is patterned (see FIG. 1J). As a result, a resistor built-in printed wiring board having the resistor 7 with high accuracy and high resistance is manufactured.

  Hereinafter, the present invention will be described in detail by way of examples.

  1. A substrate surface made of BT (bismaleimide triazine) having a thickness of 0.4 mm was washed with a conditioning cleaner (Okuno Pharmaceutical Co., Ltd .: OPC-380 Condy Clean M), and a Pd-Sn colloid solution (Okuno Pharmaceutical Co., Ltd .: OPC-). 80 catalyst) was applied with a Pd catalyst (not shown) and activated using an activator (Okuno Pharmaceutical Co., Ltd .: OPC-555 Accelerator M). Next, about 0.3 μm was plated with an electroless nickel / iron / phosphorus alloy plating solution (Okuno Pharmaceutical Co., Ltd .: Top Nicolon FY-2) to form a resistance layer. The sheet resistance of the resistance layer immediately after plating was 302 Ω / □.

  The surface plated with electroless nickel / iron / phosphorus alloy of 2.1 was plated with an electroless gold plating solution (manufactured by Uemura Kogyo Co., Ltd .: TSB71) to a thickness of 0.1 μm to form a protective layer.

  On the electroless gold-plated surface of 3.2, about 0.3 μm was plated by an electroless copper process (CUPOSIT), and about 10 μm was plated by electrolytic copper plating to form a wiring layer.

  4). A negative dry film resist (manufactured by Hitachi Chemical Co., Ltd .: RY-3215) was applied. Next, the resist was exposed through a negative and selectively exposed to ultraviolet light (UV). The negative was designed so that the resist on the wiring layer in the portion to be the wiring pattern was exposed. The non-exposed portion of the resist was removed by dipping at 30 ° C. for 60 seconds using a developer (1% aqueous sodium carbonate solution).

  5. The exposed copper layer was removed by etching at 65 ° C. using a ferric chloride solution. Next, the gold layer was etched away at 40 ° C. using potassium cyanide. Next, the nickel / iron / phosphorus layer was removed by etching at 90 ° C. using a copper sulfate-sulfuric acid solution (copper sulfate 250 g / L, sulfuric acid 5 mL / L). Next, the resist was removed with a stripping solution (5% aqueous sodium hydroxide) to form a 100 μm wide wiring pattern comprising a wiring layer, a protective layer, and a resistance layer.

  6). A negative dry film resist (manufactured by Hitachi Chemical Co., Ltd .: RY-3215) was applied. Next, the resist was exposed through a negative and selectively exposed to ultraviolet light (UV). The negative was designed so that the resist on the wiring layer in the portion to be a resistor was exposed. The non-exposed portion of the resist was removed by dipping at 30 ° C. for 60 seconds using a developer (1% aqueous sodium carbonate solution).

  7). The wiring layer (length 200 μm, width 100 μm) on the portion to be the resistor was removed by etching at 65 ° C. using a ferric chloride solution to expose the lower metal.

  8). After removing the resist with a stripping solution (5% aqueous sodium hydroxide solution), the wiring layer was subjected to surface roughening treatment by CZ treatment (manufactured by MEC).

  9. Next, the exposed gold layer was etched away using potassium cyanide at 40 ° C. to form a resistor.

  10. A BT resin was further laminated on the resistor to form an insulating layer, vias were formed, filled via plating was performed, and the resistor was made conductive, and at the same time, a wiring layer was formed on the insulating layer. The wiring layer was patterned to produce a resistor-embedded printed wiring board according to the present invention.

  11. As a result of measuring the resistance of the resistor, it was 615Ω, which was almost equal to the theoretical value 604Ω of the resistor.

[Comparative example]
A copper foil and a resistance layer of Omega-Ply (made by Omega Tcnologies) having a sheet resistance of 50Ω / □ and a resistance layer (nickel / phosphorus) thickness of 0.20 μm are collectively etched at 65 ° C. using a ferric chloride solution to 100 μm. The wiring pattern was formed. The wiring layer (length 200 μm, width 100 μm) on the portion to be the resistor was removed by etching using an alkaline etching solution (Meltex: A process), and the lower resistor layer was exposed to form a resistor. . As a result of measuring the resistance of the resistor, it was 147Ω, which was considerably larger than the theoretical value of 100Ω.

It is sectional drawing which shows the process of the manufacturing method of the printed wiring board concerning Claim 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulating substrate 2 ... Resistance layer 3 ... Protective layer 4 ... Wiring layer 5 ... Etching resist 6 ... Wiring pattern 7 ... Resistor 8 ... Insulating layer 9 ... Wiring layer

Claims (3)

In the method of manufacturing a resistor-embedded printed wiring board,
(A) a step of forming a resistance layer on the insulating substrate by plating;
(B) forming a protective layer on the resistive layer;
(C) forming a wiring layer on the protective layer;
(D) forming an etching resist on the wiring layer;
(E) forming a wiring pattern comprising the wiring layer, the protective layer, and the resistance layer by etching the wiring layer, the protective layer, and the resistance layer, and then removing the etching resist;
(F) forming an etching resist on the wiring pattern;
(G) a step of etching a predetermined wiring layer to expose a lower protective layer;
(H) removing the etching resist and roughening the surface of the wiring layer;
(I) forming a resistor by etching the exposed protective layer;
(J) laminating an insulating resin on the resistance layer to form an insulating layer;
(K) forming a via and forming a wiring layer on the insulating layer at the same time as making the resistor conductive;
(L) a step of patterning the wiring layer;
Equipped with,
A method for manufacturing a resistor-embedded printed wiring board, wherein the material for forming the protective layer is gold .   2. The method of manufacturing a resistor-embedded printed wiring board according to claim 1, wherein the resistive material forming the resistance layer is a material made of a nickel-phosphorus binary alloy or a nickel-phosphorus ternary alloy. . In the step (e), after the wiring layer is etched, the protective layer and the resistance layer are cut by sand blasting or wet blasting to form a wiring pattern including the wiring layer, the protective layer, and the resistance layer. The method for manufacturing a printed wiring board with a built-in resistor according to claim 1 or 2 .

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