JP2738600B2 - Circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board used for a hybrid integrated circuit device or the like, and more particularly, to a circuit board made of a high melting point metal such as tungsten (W), molybdenum (Mo), and manganese (Mn). The present invention relates to an improvement of a circuit board having a wiring conductor having a circuit conductor made of copper (Cu) on an outer surface.

[0002]

2. Description of the Related Art Conventionally, a hybrid integrated circuit device in which a plurality of active parts such as semiconductor elements and passive parts such as resistors and capacitors are mounted to form a predetermined electronic circuit is usually provided with tungsten, Prepare a circuit board having a structure in which a circuit conductor made of copper is attached to the outer surface of an insulating base in which a wiring conductor made of a high melting point metal such as molybdenum or manganese is embedded so that a part of the circuit conductor is connected to the wiring conductor. Then, a semiconductor element, a capacitor, a resistor, and the like are mounted on the surface of the circuit board, and each electrode terminal is joined to the circuit conductor via solder (Sn-Pb alloy) or the like. .

A circuit board used in such a conventional hybrid integrated circuit device is generally manufactured by employing a ceramic laminating technique and a thick film technique such as screen printing. Produced by

[0004] First, an organic solvent is added to a ceramic raw material powder such as alumina (Al ₂ O ₃ ), silica (SiO ₂ ), magnesia (MgO), and calcia (CaO) which has excellent electrical insulation properties.
A solvent is added and mixed to obtain a plurality of ceramic raw sheets, and a conductive paste made of a high melting point metal powder such as tungsten, molybdenum, manganese or the like is formed on the upper and lower surfaces of each ceramic raw sheet by a conventionally known thick film method such as screen printing. Is applied in a predetermined pattern by printing.

Next, the respective ceramic green sheets are laminated to obtain a laminate, which is fired at a temperature of about 1500 ° C., and has a wiring conductor made of a refractory metal such as tungsten, molybdenum, manganese or the like inside and on the surface. Obtain an insulating substrate.

Finally, on the outer surface of the insulating substrate,
A copper paste obtained by adding and mixing an organic solvent and a solvent to copper (Cu) powder is partially partially
It is applied so as to be connected to the wiring conductor, and after that,
This is fired in a neutral atmosphere (nitrogen atmosphere) at a temperature of about 900 ° C to form alumina (Al ₂ O ₃ ) and copper to form an insulating substrate.
(Cu), and a circuit conductor composed of copper powder is firmly adhered to the insulating substrate by depositing a compound of copper aluminate (CuAl ₂ O ₃ ) at the interface between the insulating substrate and the copper powder, This results in a circuit board as a product.

[0007]

However, in this conventional circuit board, a compound called copper aluminate is deposited on the interface between the circuit conductor and the insulating substrate in order to firmly adhere the circuit conductor on the insulating substrate. , The copper aluminate is tin (Sn)
Is easily dissociated (the bond of the compound is broken and separated into each component). For this reason, when an electrode terminal of a semiconductor element, a capacitor, a resistor, or the like is joined to the circuit conductor of the circuit board via solder (Sn-Pb alloy) to form a hybrid integrated circuit device, the hybrid integrated circuit device operates during operation. Heat (about 150
(° C) is applied, the tin of the solder that joins the electrode terminals of the capacitor and the like to the circuit conductor diffuses into the copper aluminate at the interface between the circuit conductor and the insulating substrate, and as a result, the circuit conductor is firmly attached to the insulating substrate. The copper aluminate to be adhered to the substrate is dissociated, and the adhesion strength of the circuit conductor is greatly degraded.
In addition, there is a disadvantage that the reliability of the hybrid integrated circuit device is greatly reduced.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to tungsten,
In a circuit board, a circuit conductor made of copper is adhered on an outer surface of an insulating base provided with a wiring conductor made of at least one of molybdenum and manganese so that a part of the circuit conductor is connected to the wiring conductor. An intermediate metal layer made of a metal mainly containing an alloy of at least one of nickel, cobalt, tungsten, and at least one of molybdenum and boron is interposed on a joint surface between the conductor and the circuit conductor. The outer surface contains at least one of nickel, iron, and manganese as main components, and tungsten is 2.0
A coating layer containing from about 10.0% by weight to about 10.0% by weight.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a partially enlarged sectional view for explaining a circuit board of the present invention, and 1 is an insulating base made of an electrically insulating material.

The insulating substrate 1 is made of, for example, an electrically insulating material such as alumina ceramics, and is made of alumina (Al ₂ O).
₃ ), silica (SiO ₂ ), magnesia (MgO), calcia
An organic solvent is added to a ceramic raw material powder such as (CaO), a solvent is added and mixed to form a slurry, and a ceramic raw sheet is obtained by employing a doctor blade method,
Thereafter, the ceramic green sheet is subjected to an appropriate drilling process and a plurality of the sheets are laminated, and in a reducing atmosphere, about 1500 ° C.
It is manufactured by firing at a temperature of

The insulating substrate 1 is provided with a wiring conductor 2 extending from the inside to the upper surface, and the wiring conductor 2 is formed of at least one of tungsten, molybdenum, and manganese.

The wiring conductor 2 is prepared by adding and mixing an organic solvent and a solvent to powder of tungsten, molybdenum, and manganese to form a conductor paste, and printing the conductor paste on the upper and lower surfaces of the ceramic green sheet in a predetermined pattern by screen printing or the like. By being applied, it is adhered to the inside and the surface of the insulating base 1.

A circuit conductor 3 made of copper (Cu) is adhered to the surface of the insulating base 1 including the exposed outer surface of the wiring conductor 2, and the circuit conductor 3 is provided with an active component such as a semiconductor element or a resistor. Each electrode terminal of a passive component such as a container or a capacitor is connected.

The circuit conductor 3 is formed by adding an organic solvent and a solvent to copper powder to form a copper paste, and applying the copper paste to the outer surface of the insulating base 1 so that a part of the copper paste is connected to the wiring conductor 2. Print and apply, and then, in a neutral atmosphere,
By sintering at a temperature of about 900 ° C., the alumina and copper forming the insulating substrate 1 react with each other, and a copper aluminate compound is precipitated at the interface between the insulating substrate 1 and the copper powder, thereby forming an insulating substrate.
1 Deposited on the outer surface.

The bonding surface between the wiring conductor 2 and the circuit conductor 3 is made of a metal mainly composed of an alloy of at least one of nickel (Ni) and cobalt (Co) with tungsten and at least one of molybdenum and boron. When an intermediate metal layer made of is formed on the wiring conductor 2, the intermediate metal layer greatly improves the wettability (reactivity) between the wiring conductor 2 and the circuit conductor 3 and completely connects the wiring conductor 2 and the circuit conductor 3. And the electrical conduction between the two can be made extremely excellent.

Further, at least one of the above nickel and cobalt
An intermediate metal layer made of a metal mainly containing an alloy of one kind with tungsten and at least one kind of molybdenum with boron has a total weight of tungsten and molybdenum of nickel,
If the total weight of cobalt is less than 2.0% of the total weight of 100, a part of the copper constituting the circuit conductor 2 diffuses into the intermediate metal layer and directly contacts the wiring conductor 2 to adhere to the wiring conductor 2 and the circuit conductor 3. And the total weight of tungsten and molybdenum is 10% of the total weight of nickel and cobalt.
If it exceeds 50.0% with respect to 0, the wettability (reactivity) between the intermediate metal layer and the circuit conductor 3 deteriorates, and the circuit conductor 3 is connected to the wiring conductor.
(2) Since the intermediate metal layer tends to be unable to adhere with good adhesion, the total weight of tungsten and molybdenum is 2.0
It is desirable to set the range to 50.0%.

Further, when the content of boron contained in the intermediate metal layer is less than 0.1% by weight, an oxide film is formed on the surface of the intermediate metal layer, and the adhesion between the intermediate metal layer and the circuit conductor 3 is deteriorated. When the content exceeds 3.0% by weight, the intermediate metal layer becomes hard and brittle, and when heat stress such as temperature cycling is applied, cracks are generated, resulting in poor electrical conduction between the wiring conductor 2 and the circuit conductor 3. Tend to be. Therefore, the boron contained in the intermediate metal layer has a content of 0.1 to 3.
It is desirable to keep the range of 0% by weight.

Further, the intermediate metal layer has a thickness of 0.1
If it is less than μm, a part of the copper forming the circuit conductor 3 diffuses in the intermediate metal layer and directly contacts the wiring conductor 2 to form the wiring conductor.
The adhesion between 2 and the circuit conductor 3 tends to deteriorate.
If the thickness exceeds 0.0 μm, a crack occurs due to internal stress in the intermediate metal layer, and a part of the circuit conductor 3 directly contacts the wiring conductor 2 via the crack in the intermediate metal layer, and the wiring conductor 2 and the circuit conductor 3 adhere to each other. It is preferable that the thickness of the intermediate metal layer be in the range of 0.1 to 10.0 μm because the property tends to deteriorate.

The circuit conductor 3 adhered to the outer surface of the insulating base 1 further includes a coating layer 4 mainly composed of at least one of nickel (Ni), iron (Fe) and manganese (Mn) on the outer surface. Is coated by a conventionally known electrolytic plating method or an electroless plating method, and when the electrode terminal such as a semiconductor element or a capacitor is joined to the circuit conductor 3 via solder, the coating layer 4 Improves solder wettability and improves circuit conductors
The third function is to firmly join the electrode terminals of semiconductor elements and capacitors.

The coating layer 4 functions to effectively prevent the diffusion of tin contained in the solder. Even if electrode terminals such as a semiconductor element and a capacitor are connected to the circuit conductor 3 via solder, the coating layer 4 may be used. Does not diffuse to the interface between the circuit conductor 3 and the insulating base 1, and the tin contained in the solder does not dissociate the copper aluminate which firmly adheres the circuit conductor 3 to the insulating base 1. Therefore, the circuit conductor 3 is always firmly adhered on the insulating base 1.

The coating layer 4 is made of a metal mainly containing at least one of nickel, iron and manganese, and may contain less than 20.0% by weight of a metal such as molybdenum or tungsten in nickel, iron or manganese. . Particularly, when tungsten is contained in an amount of 2.0 to 10.0% by weight, nickel,
The diffusion rate of tin into the coating layer 4 made of a metal containing at least one of iron and manganese as a main component is remarkably reduced, and the adhesion strength between the circuit conductor 3 and the insulating base 1 is more effectively prevented from lowering. be able to. Accordingly, it is preferable that the coating layer 4 contains 2.0 to 10.0% by weight of tungsten.

If the thickness of the coating layer 4 is less than 0.01 μm, the coating layer 4 cannot effectively prevent the diffusion of tin contained in the solder, and the coating of the circuit conductor 3 on the insulating base 1 cannot be prevented. When the thickness exceeds 12.0 μm, the stress at the time of plating is large in the coating layer 4 and the coating layer 4 tends to peel off from the circuit conductor 3 even when a small external force is applied. Therefore, the coating layer 4 has a thickness of 0.
It is preferable that the thickness be in the range of 1 to 12.0 μm.

Further, when a layer made of gold (Au) is applied on the outer surface of the coating layer 4 to a thickness of 0.1 to 5.0 μm, oxidation corrosion of the coating layer 4 can be effectively prevented, and a semiconductor element or a capacitor can be formed. And the like can be more firmly joined to the circuit conductor 3. Therefore, it is preferable to further coat a layer made of gold in the range of 0.1 to 5.0 μm on the outer surface of the coating layer 4.

Thus, the circuit board has a semiconductor element, a resistor, a capacitor, and the like mounted on the surface thereof, and the semiconductor element and the like are joined to circuit conductors via solder to form a hybrid integrated circuit device.

[0025]

According to the circuit board of the present invention, a metal mainly composed of an alloy of at least one of nickel and cobalt and tungsten and at least one of molybdenum and boron is provided on the joint surface between the wiring conductor and the circuit conductor. And an intermediate metal layer consisting of at least one of nickel, iron and manganese is layered on the outer surface of the circuit conductor, so that the wiring conductor and the circuit conductor are separated from each other. The electrical connection between the two can be made extremely excellent by bringing them into close contact, and even if the electrode terminals of a semiconductor element or a capacitor are joined to the circuit conductor via solder, the tin contained in the solder is Does not diffuse to the interface between the circuit conductor and the insulating substrate, and the copper conductor deposited on the interface between the circuit conductor and the insulating substrate is free from dissociation, and the circuit conductor is always dispersed on the insulating substrate. It becomes possible to firmly adhered, is extremely useful as a circuit board for use in the hybrid integrated circuit device or the like.

[Brief description of the drawings]

FIG. 1 is a partially enlarged cross-sectional view for explaining a circuit board according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating base 2 ... Wiring conductor 3 ... Circuit conductor 4 ... Cover layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-127194 (JP, A) JP-A-63-144554 (JP, A) JP-A-61-236192 (JP, A) JP-A-59-127 117189 (JP, A) JP-A-63-110697 (JP, A) JP-B-63-42879 (JP, B2)

Claims (1)

(57) [Claims] 1. A circuit conductor made of copper is adhered to an outer surface of an insulating substrate provided with a wiring conductor made of at least one of tungsten, molybdenum, and manganese so that a part of the circuit conductor is connected to the wiring conductor. circuit Oite on board, the
Nickel or cobalt is applied to the joint surface between the wiring conductor and the circuit conductor.
And at least one of tungsten and molybdenum
At least one alloy consisting of an alloy of boron and a metal
And a coating layer containing at least one of nickel, iron, and manganese as a main component and containing 2.0 to 10.0% by weight of tungsten on the outer surface of the circuit conductor. Circuit board.