Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
2001-06-20
2003-12-09
Lam, Cathy (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C428S607000, C428S209000, C216S041000, C216S074000, C216S075000
Reexamination Certificate
active
06660406
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a copper foil for forming a resistor circuit used in the manufacture of a printed wiring board with nickel resistor circuits, and a printed wiring board comprising such a resistor circuit; and to a printed wiring board comprising such a resistor circuit.
2. Description of the Prior Art
Such a printed wiring board with resistor circuits is used in electric and electronic equipment that requires resistance control. Particularly with a rapid increase in the clock frequencies of computers in recent years, a resistor circuit of considerably high accuracy has been demanded increasingly on a circuit substrate.
It has been pointed out that the thickness of the nickel layer forming the resistor circuit should be uniform, and the width of the resistor circuit should be uniformly controlled in order to improve the accuracy of the finished resistor circuit, and is a matter of course in considering the electrical resistance of metals.
A conventional printed wiring board with resistor circuits has been manufactured by forming a nickel layer for forming the resistor circuit on a surface of a base material used for bonding a copper that has undergone a nodular treatment (a treatment for depositing fine copper grains to obtain the anchoring effect), forming copper foil circuits on the copper foil side or forming a resistor circuit on a nickel layer for forming the resistor circuit, and bonding the nickel layer to the base material.
Alternatively, there has generally been adopted a method for manufacturing a printed wiring board with resistor circuits by forming copper foil circuits on a copper foil layer using an electrodeposited copper foil with carrier, bonding the copper foil circuits on a base material, removing the carrier, thereafter forming a nickel layer for forming the resistor circuit using a plating method, and forming nickel resistor circuits using an etching method.
However, since the above-described method for manufacturing a printed wiring board with resistor circuits, by using a copper foil having a nickel layer for the resistor circuit formed on the nodulated surface side used for bonding the copper foil on the base material, is affected by the uneven nodulated surface, the thickness of the nickel layer easily become uneven, and a resistor circuit of high accuracy cannot been formed.
Also when an electrodeposited copper foil with carrier is used, there has been a problem that the dimensional accuracy as a printed wiring board is deteriorated when the carrier consisting of a different metal such as aluminum is removed after copper foil circuits are formed in the state of an electrodeposited copper foil with carrier, and bonding the copper foil to the base material.
SUMMARY OF THE INVENTION
The present inventors conducted repeated studies, and discovered a method for an electrodeposited copper foil with carrier that can be used for manufacturing a printed wiring board with resistor circuits having an excellent accuracy of the completed resistor circuit and an excellent dimensional stability of the completed printed wiring board; and a method for manufacturing such a printed wiring board with resistor circuits. The present invention will be described below.
The invention is a composite copper foil with carrier for manufacturing a printed wiring board with resistor circuits comprising a metal layer for forming the resistor circuit between a copper carrier and a copper layer for forming the circuit. The metal layer for forming the resistor circuit is characterized to be a nickel layer or a nickel alloy layer. A schematic sectional view showing the composite copper foil with carrier is shown in FIG.
1
. When the cross-section is viewed, a nickel layer or a nickel alloy layer to be a metal layer for forming the resistor circuit is positioned in the location sandwiched between the copper carrier and the copper layer for forming the circuit. Although
FIG. 1
shows the outer surface of the copper layer for forming the circuit that has undergone a nodular treatment, this nodular treatment is optional. As is obvious from the following description of the manufacturing method, since the copper foil circuits formed of the copper layer for forming the circuit of the composite copper foil with carrier according to the present invention is embedded when processed into a printed wiring board, the bonding strength of the copper foil circuits to an insulating material does not become an issue even if the nodular treatment is omitted. The nodular treatment is a treatment to deposit copper microparticles by burn plating of copper in the same manner as normally conducted to the bonding surface of copper foil, and to fix these copper microparticles by level plating of copper to prevent the separation of these copper microparticles. Since the copper carrier is made of the same material as the copper foil layer for forming the circuit, such a structure can minimize the dimensional change of the substrate after removing the carrier. Furthermore, since the nickel layer or the nickel alloy layer to be a metal layer for forming the resistor circuit is formed on the flat surface of the copper foil, a fine resistor circuit can be formed, the degree of freedom for the design of the resistor circuit increases, and the stability of the resistance values is improved.
A so called copper foil is used as the copper carrier and it may be formed of either an electrodeposited copper foil or a rolled copper foil. The composite copper foil with carrier according can use the copper foil layer itself for the carrier as the conductor. Therefore, when the metal layer for forming the resistor circuit and the copper foil layer for forming the circuit is manufactured by the electrodepositing method, the copper carrier can be used as the base material for electrodepositing the nickel layer or the nickel alloy layer to be a metal layer for forming the resistor circuit and the copper foil layer for forming the circuit on the surface of the copper carrier, by cathode-polarizing the copper carrier in a prescribed solution. Also, when the metal layer for forming the resistor circuit and the copper layer for forming the circuit are manufactured by sputtering or vapor deposition, the copper carrier can be used as an electrode to impress a voltage to the facing electrode, and nickel for forming the metal layer for forming the resistor circuit, and copper for forming the copper foil layer for forming the circuit can be deposited efficiently on the surface of the copper carrier.
Since the surfaces of the copper carrier and the copper foil layer for forming the circuit are normally exposed to the air, rust prevention treatment is generally performed for preventing oxidation during hot pressing for manufacturing a copper clad laminate, using an inorganic element such as zinc or a zinc alloy, or an organic agent such as benzotriazole or imidazole to secure the storage stability of the composite copper foil with carrier for a long period of time. When copper microparticles are formed and the nodular treatment is performed, the same rust prevention treatment is performed on the surface after the nodular treatment. However, since such a rust prevention layer is an extremely thin film, it is omitted from the description of the composite copper foil with carrier.
The composite copper foil with carrier is used for manufacturing a printed wiring board with resistor circuits using the etching method that will be described later. Therefore, the thickness of the nickel layer or the nickel alloy layer to be a metal layer for forming the resistor circuit provided between the copper carrier and the copper foil layer for forming the circuit is adequately determined in consideration of the manufacturing method. However, the composite copper foil with carrier, may be of a peelable type from which the carrier can be released. In such a case, a metal layer, an organic layer, or another inorganic layer may be provided as an interface layer betwe
Kataoka Takashi
Takahashi Naotomi
Yamamoto Takuya
Lam Cathy
Mitsui Mining & Smelting Co. Ltd.
Roberts & Mercanti LLP
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