JPH04357895A - Manufacture of ceramic wiring board - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a ceramic wiring board having a conductor circuit which is not oxided and erased by a baking process and has a small conductor resistance. CONSTITUTION:A method of manufacturing a ceramic wiring board comprises steps for forming a copper film 3 by plating after depositing a Ni plated film 2 including boron on a ceramic substrate 1, providing a plurality of conductor circuits by etching, then depositing a Ni plated film 4 including boron and then a plated layer 5 of a noble metal to the conductor circuit and then baking the ceramic wiring board under the atmospheric condition after printing a resistance body between conductor circuits.

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 ceramic wiring board, and more particularly to a method of manufacturing a wiring board in which a copper pattern and a resistor are formed on the surface layer.

0002

[Prior Art] In response to the recent demand for higher density electronic circuits,
Ceramic wiring boards that are light, thin, short, and highly reliable are in practical use. Conventional ceramic wiring boards with resistors are manufactured by forming noble metal conductor circuits using silver, silver-palladium, etc. pastes and resistors using ruthenium, carbon, etc. pastes using a printing method, and then firing them in the atmosphere. . This manufacturing method is generally known as a thick film type ceramic wiring board.

0003

[Problems to be Solved by the Invention] When manufacturing the above-mentioned ceramic wiring board, wiring of noble metal layers such as gold, silver, platinum, etc., and metal layers using nickel and copper is generally performed using an inexpensive printing method. Formation is the mainstream. However, with this method, it is difficult to form fine circuits, and at the same time, the paste material for the noble metal layer, nickel, and copper metal layer contains a glass component to improve the adhesive strength of the conductor circuit, and the conduction resistance value There are disadvantages such as a high value and low reliability. Furthermore, this thick film circuit is equipped with a ruthenium-based resistor that is normally fired in the atmosphere. However, wiring boards using nickel and copper metal pastes and conductor circuits obtained by nickel plating and copper plating do not change resistance at present because the circuits oxidize and disappear when sintering resistors in the atmosphere. Only carbon-based resistors with high carbon resistance can be used, and there are problems such as poor reliability.

The object of the present invention is to provide a method for manufacturing a ceramic wiring board that does not have the above-mentioned drawbacks.

[0005]

[Means for Solving the Problems] The present invention involves plating a ceramic substrate with nickel containing boron, followed by copper plating and etching to form a plurality of conductor circuits, and then forming a plurality of conductor circuits containing the boron. The present invention relates to a method for manufacturing a ceramic wiring board, which involves nickel plating, then noble metal plating, and printing a resistor between conductor circuits, followed by firing in the atmosphere.

[0006] The present invention aims to coat a conductor circuit with a nickel plating layer containing boron and a noble metal plating layer having excellent oxidation resistance to prevent oxidation loss due to firing in the atmosphere. In the present invention, a known ceramic substrate such as an alumina substrate is used as the ceramic substrate. It is preferable that the surface of the ceramic substrate be roughened in advance by alkali melting or the like. Formation of the conductor circuit, boron-containing nickel plating, noble metal plating, printing and firing of the resistor are performed by known methods. The copper coating of the conductor circuit is formed by plating to reduce resistance. It is preferable that the pattern of the conductor circuit is formed by an additive method using a photolithography method for fine circuits, since this enables high-density wiring and has excellent pattern accuracy. There are no particular restrictions on the type of noble metal plating layer. There are no restrictions on the type of resistor. The firing temperature is 300~
750°C is preferred.

The sequence of the present invention will be explained with reference to FIG. After the surface of the ceramic substrate 1 is roughened, a Ni-boron film 2 is formed on the entire surface by plating, and a copper film 3 is further formed by plating. Subsequently, a photolithographic layer is provided on the surface of the copper film 3 and etched to form a conductive circuit. Thereafter, a Ni-boron coating 4 is formed again by plating, and a noble metal plating layer 5 is formed thereon, and then a resistor 6 is formed between the conductor circuits by a printing method, and finally, this is fired in the atmosphere to form a ceramic wiring board. This is what you get.

[0008]

[Examples] Examples of the present invention will be described below.

Example 1 An alumina substrate with a purity of 96% and a thickness of 1.0 mm was heated at 350°C.
The entire surface of the alumina substrate was uniformly roughened by immersing it in an alkali molten salt for 5 minutes, and then neutralized with a 10% by weight sulfuric acid solution and washed with water. After that, it was immersed in an active solution (manufactured by World Metal Co., Ltd., trade name AT-80) to impart palladium.
Next, a Ni-boron film was formed to a thickness of 2 μm using an electroless Ni-B solution (manufactured by World Metal Co., Ltd., trade name Niboron M2), and then washed with water. On this Ni-boron plating film, electroless copper plating solution (manufactured by Hitachi Chemical KK, trade name: L-
59) to form a copper plating layer with a thickness of 20 μm. Photosensitive resist film after plating (manufactured by Hitachi Chemical KK, trade name Photik PHT-862AF-25
) was attached to the entire copper plating layer, and then a negative film with a transparent part formed in the same shape as the conductor circuit to be obtained was attached to the upper surface, exposed to ultraviolet light, and developed with a sodium carbonate solution. After that, it was etched with copper chloride,
The unnecessary copper plating layer and Ni-boron plating layer were removed. The photosensitive resist film was then stripped with a 5% sodium hydroxide solution. Thereafter, these conductor circuits were coated with a 2 μm electroless Ni-boron plating film using the electroless Ni-B solution used previously, and then a 2 μm gold plating film using the gold plating solution, washed with water, and dried. As a result, a wiring board having a copper conductor circuit whose entire surface was covered with an oxidation-resistant Ni-boron film was obtained. Next, ruthenium resistors (Shoei Kagaku Kogyo K.
(manufactured by K. K., trade name: R-2000 series, R-2310) was printed and fired at 550° C. for 10 minutes in the atmosphere to form a resistor. Ceramic wiring boards having conductor circuits made of Ni-boron, copper, and gold coatings obtained by the above-mentioned manufacturing method can be fired at 550°C in the atmosphere without increasing conduction resistance or oxidizing the copper circuits. It was confirmed that it can be used.

Example 2 After roughening an alumina substrate and forming an electroless Ni-boron plating film of 2 μm in the same manner as in Example 1, a copper film was formed by electrolytic copper plating (manufactured by Nippon Electroplating Engineers, trade name Qubus EF). A thickness of 20 μm was applied, photolithography and etching were performed in the same manner as in Example 1, and a Ni-boron plating film and a gold plating film of 2 μm each were applied thereon to obtain a wiring board having a conductive circuit. Furthermore, a resistor (manufactured by Sumitomo Metal Mining KK, product name R-H series, R-131) was formed between these conductor patterns by a printing method, and heated at 650°C for 1
Firing was performed in the air for 0 minutes. As in Example 1, no problems were observed in the obtained ceramic wiring board even at 650°C.

Comparative Example 1 An alumina substrate was roughened in the same manner as in the example. Catalyst treatment (manufactured by Hitachi Chemical Co., Ltd., trade name HS-101B) for imparting palladium was then applied to the surfaces of these substrates, and a 20 μm copper plating layer was obtained by electroless plating in the same manner as in Example 1. Next, as in Example 1, a wiring board having a conductive circuit made of copper metal on the surface of an alumina substrate was obtained by an additive method using photolithography. Thereafter, resistor printing was performed in the same manner as in Example 1, followed by firing in the atmosphere to obtain a ceramic wiring board. However, the conductor circuit made of this copper plating layer disappeared due to oxidation during firing in the atmosphere at 550°C.

0012

Effects of the Invention According to the present invention, a copper conductor circuit can be made of Ni-
Since it is coated with a layer of boron and a noble metal, it is possible to prevent the conductive circuit from being lost due to oxidation during firing, and it becomes possible to perform firing in the air, which was previously impossible. Furthermore, since the copper film is formed by plating, the purity of the copper is high and the resistance of the conductor circuit can be lowered, and in addition, there is an advantage that fine circuits can be formed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the order of the manufacturing method of the present invention.

[Explanation of symbols]

1 Ceramic substrate
2 Ni-Boron coating 3 Copper coating
4 Ni-boron coating

Claims (1)

[Claims] 1. A ceramic substrate is plated with nickel containing boron, then copper plated and then etched to form a plurality of conductor circuits, and then the conductor circuits are plated with nickel containing boron and then with a precious metal. A method for manufacturing a ceramic wiring board, further comprising disposing a resistor between the conductor circuits by printing, and then firing in the atmosphere.