JP2931910B2 - Circuit board - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a circuit board used for a hybrid integrated circuit device or the like, and more particularly, to tungsten (W), molybdenum (Mo), manganese (Mn) inside. The present invention relates to an improvement of a circuit board having a wiring conductor made of a metal having a high melting point and a circuit conductor made of copper (Cu) on an outer surface.

(Prior art and its problems) Conventionally, a hybrid integrated circuit device in which a large number of active components such as semiconductor elements and passive components such as resistors and capacitors are mounted to constitute a predetermined electronic circuit is usually provided internally. A circuit conductor made of copper (Cu) contacts a part of the circuit conductor made of copper (Cu) on an outer surface of an insulating base in which a wiring conductor made of a refractory metal such as tungsten (W), molybdenum (Mo), and manganese (Mn) is embedded. Prepare a circuit board having a structure attached in such a manner that a semiconductor element, a capacitor, a resistor, and the like are mounted on the surface of the circuit board, and electrodes of the semiconductor element and the like are connected to the circuit conductor. This results in a hybrid integrated circuit device.

Circuit boards used in such conventional hybrid integrated circuit devices and the like are generally manufactured by employing a ceramic lamination technology and a thick film technology such as screen printing,
Specifically, it is manufactured by the following method.

First, an organic solvent and a solvent are added to a ceramic raw material powder such as alumina (Al ₂ O ₃ ) having excellent electrical insulation to obtain a plurality of raw ceramic sheets, and a plurality of raw ceramic sheets are obtained. A conductive paste made of a refractory metal powder such as tungsten (W), molybdenum (Mo), manganese (Mn) or the like is printed and applied in a predetermined pattern by employing a conventionally known thick film technique such as screen printing.

Next, the above ceramic green sheets are laminated to obtain a laminate, which is fired at a temperature of about 1500 ° C., and a high melting point metal such as tungsten (W), molybdenum (Mo), manganese (Mn) is formed inside and on the surface. An insulating substrate having a wiring conductor made of

Finally, a copper paste obtained by adding and mixing a glass powder, an organic solvent, and a solvent to copper (Cu) powder on the outer surface of the insulating base is partially contacted with the wiring conductor by a conventionally well-known screen printing method. This is fired at a temperature of about 800 ° C. in a neutral atmosphere (nitrogen atmosphere), and copper (Cu) powder is deposited on the insulating base and the wiring conductor, thereby forming a circuit board and Become.

However, this conventional circuit board has poor wettability (reactivity) between tungsten (W), molybdenum (Mo), etc., which forms the wiring conductor, and copper (Cu), which forms the circuit conductor. Even if a circuit conductor is partially adhered, the adhesion between them is poor, and as a result, there is a disadvantage that the electrical conduction between the wiring conductor and the circuit conductor is extremely poor.

Therefore, in view of the above-mentioned drawbacks, tungsten (W), molybdenum (M)
o) and a coating layer made of nickel, cobalt or the like having good wettability (reactivity) with copper (Cu) is applied to improve the adhesion between the wiring conductor and the circuit conductor. See No. 58-30194).

However, in this case, the copper (Cu) paste is heated to about 800 ° C.
When the circuit conductor is baked at the above temperature and the circuit conductor is applied on the wiring conductor with the coating layer interposed, copper (Cu) forming the circuit conductor and nickel (Ni), cobalt (Co), etc. forming the coating layer Inter-diffusion occurs between the wiring conductor and some of the copper (Cu) in the circuit conductor directly contacts the wiring conductor made of tungsten (W) or molybdenum (Mo) with poor wettability (reactivity), and Adhesion with the circuit conductor deteriorates, and at the same time, electrical conduction between the two is good immediately after deposition, but when stress such as temperature cycling is applied due to the difference in thermal expansion coefficient between the wiring conductor and the circuit conductor There was a disadvantage that it was greatly reduced.

(Object of the Invention) The present invention has been devised in view of the above-mentioned drawbacks, and its object is to provide a wiring conductor made of at least one of tungsten (W), molybdenum (Mo), and manganese (Mn) and copper (Cu). It is an object of the present invention to provide a circuit board which can be used for a hybrid integrated circuit device or the like by significantly improving the adhesion to the circuit conductor and improving the electrical conduction between the two.

(Means for Solving the Problems) According to the present invention, a circuit conductor made of copper is formed on an outer surface of an insulating substrate provided with a wiring conductor made of at least one of tungsten, molybdenum, and manganese, and a part of the circuit conductor makes contact with the wiring conductor. In the circuit board thus adhered, an intermediate metal layer mainly composed of an alloy of at least one of nickel and cobalt and at least one of tungsten and molybdenum is provided at a contact portion between the wiring conductor and the circuit conductor. It is characterized by being interposed.

(Example) Next, the present invention will be described in detail with reference to the accompanying drawings.

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 base 1 is made of an electrically insulating material such as alumina ceramics, for example, alumina (Al ₂ O ₃ ), silica (S
iO ₂ ), magnesium (MgO), calcia (CaO) and other ceramic raw material powders are mixed with an organic solvent and a solvent to form a slurry, which is then formed into a ceramic raw sheet by employing a doctor blade method. After a while
The ceramic green sheet is manufactured by subjecting the ceramic green sheet to appropriate perforation processing, laminating a plurality of sheets, and firing at a temperature of about 1500 ° C. in a reducing atmosphere.

The insulating base 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 (W), molybdenum (Mo), and manganese (Mn).

The wiring conductor 2 is made by adding and mixing an organic solvent and a solvent to a powder of tungsten (W), molybdenum (Mo), and manganese (Mn) to form a conductor paste, and the conductor paste is screen-printed on the upper and lower surfaces of the ceramic raw sheet. By applying a thick film technique such as that described above and printing and applying a predetermined pattern, the insulating substrate 1 is adhered and formed inside and on the surface.

The wiring substrate 2 has nickel (Ni), cobalt (Co)
And an intermediate metal layer 3 made of a metal whose main component is an alloy of at least one element selected from the group consisting of tungsten (W) and molybdenum (Mo). Is formed on the exposed outer surface by electroplating, electroless plating, or the like.

The intermediate metal layer 3 is composed of nickel (Ni),
A metal mainly composed of an alloy of at least one of cobalt (Co) and at least one of tungsten (W) and molybdenum (Mo) has good wettability (reactivity) to both the wiring conductor 2 and the circuit conductor 4. When the circuit conductor 4 is applied on the wiring conductor 2, the two are completely adhered to each other, and the electrical conduction between the two is extremely excellent.

Further, the metal constituting the intermediate metal layer 3 is a metal which is hardly interdiffused with copper (Cu). Therefore, even if the circuit conductor 4 is attached to the wiring conductor 2 with the intermediate metal layer 3 interposed therebetween, the circuit Part of the copper (Cu) of the conductor 4 does not directly contact the wiring conductor 2 at all, and this also makes the adhesion between the wiring conductor 2 and the circuit conductor 4 more complete, and establishes electrical continuity between the two. It can be very good.

The intermediate metal layer 3 has a total weight of tungsten (W) and molybdenum (Mo) of nickel (Ni) and cobalt (C).
If the total weight of o) is less than 2.0% of the total weight of 100, the effect of suppressing the diffusion of copper (Cu) is weakened, and the copper (Cu) constituting the circuit conductor is reduced.
Of the metal conductor 3 diffuses in the intermediate metal layer 3 and directly contacts the wiring conductor 2, which tends to deteriorate the adhesion between the wiring conductor 2 and the circuit conductor 4. In addition, tungsten (W), molybdenum (M
If the total weight of o) exceeds 50.0% with respect to the total weight of nickel (Ni) and cobalt (Co), 100, the wettability (reactivity) between the intermediate metal layer 3 and the circuit conductor 4 deteriorates, and the circuit conductor 4 is wired. The intermediate metal layer 3 is made of tungsten (W),
It is desirable that the total weight of molybdenum (Mo) be in the range of 2.0 to 50.0% based on the total weight of nickel (Ni) and cobalt (Co) of 100.

If the thickness of the intermediate metal layer 3 is less than 0.1 μm, diffusion of copper (Cu) forming a circuit conductor cannot be completely prevented, and a part of the circuit conductor 4 diffuses through the intermediate metal layer. And the wiring conductor 2 and the circuit conductor 4 in direct contact with the wiring conductor 2.
When the thickness exceeds 10.0 μm, a crack occurs in the intermediate metal layer 3 due to internal stress, and a part of the circuit conductor 4 is directly connected to the wiring conductor 2 through the crack in the intermediate metal layer 3. Contact, and the adhesiveness between the wiring conductor 2 and the circuit conductor 4 tends to deteriorate.
It is preferable that the thickness be in the range of 0.1 to 10.0 μm.

A circuit conductor 4 made of copper (Cu) is further adhered on the intermediate metal layer 3 adhered to the outer surface of the wiring conductor 2, and the circuit conductor 4 has an active component such as a semiconductor element or a resistor. Passive components such as capacitors and capacitors are connected.

The circuit conductor 4 is formed by adding and mixing a glass powder, an organic solvent, and a solvent to copper (Cu) powder to form a copper paste, and applying the copper paste to the intermediate metal layer 3 partially adhered to the wiring conductor 2. Printing is performed on the outer surface of the insulating substrate 1 so as to be in contact with the substrate, and thereafter, the resultant is baked at a temperature of about 800 ° C. in a neutral atmosphere to be applied to the outer surface of the insulating substrate 1.

In this case, since the circuit conductor 4 is hardly diffused on the outer surface of the wiring conductor 2 and the intermediate metal layer 3 made of a metal having good wettability (reactivity) with the circuit conductor 4 is provided, the wiring conductor 2 The circuit conductor 4 can be adhered with good adhesion and good electrical continuity between the two.

In this way, the circuit board becomes a constituent integrated circuit device by mounting semiconductor elements, resistors, capacitors and the like on its surface and connecting each electrode of the semiconductor elements and the like to circuit conductors.

(Example) Next, the operation and effect of the present invention will be described based on examples described below.

First, tungsten (W) and molybdenum (M) are placed on the upper surface of a green ceramic sheet mainly composed of alumina (Al ₂ O ₃ ).
o) Conductive paste consisting of powder of the above is printed and applied, and the width is 1.0m.
m, a pair of patterns with a length of 10.0 mm, the distance between the tips is 5.0
Then, this is fired at a temperature of 1500 ° C. in a reducing atmosphere to form a wiring conductor made of the material shown in Table 1 on an insulating base made of an alumina sintered body.

Next, an intermediate metal layer having the composition and thickness shown in Table 1 is applied to the surface of the wiring conductor by electrolytic plating or electroless plating.

Then, a copper (Cu) paste is printed to a thickness of about 30 μm between the pair of wiring conductors and fired at a temperature of 800 ° C. in a neutral atmosphere to form circuit conductors.

The copper (Cu) paste was brought into contact with the wiring conductor such that the copper (Cu) paste was in contact with the tip 1.0 mm of the wiring conductor.

Finally, the initial electric resistance between the pair of wiring conductors and the electric resistance after 100 cycles of a temperature cycle test at −65 to + 150 ° C. are measured, the rate of change (rate of increase) is determined, and the average value is obtained. Was calculated, and the magnitude of the average increase rate was used as the evaluation of the electrical continuity between the wiring conductor and the circuit conductor.

Sample numbers 24 and 25 are comparative samples for comparison with the products of the present invention, in which a layer of nickel (Ni) or cobalt (Co) is applied to the surface of the wiring conductor.

 The results are shown in Table 1.

As can be seen from the above experimental results, the conventional wiring conductor with a nickel (Ni) or cobalt (Co) layer deposited on the surface has a large increase in electrical resistance of 81.0% or more, and the circuit conductor is deposited. At the time, interdiffusion occurs between copper (Cu) constituting the circuit conductor and nickel (Ni) or cobalt (Co) deposited on the surface of the wiring conductor, resulting in adhesion between the wiring conductor and the circuit conductor. Is deteriorated and the electrical conduction between the two is poor. On the other hand, at least one of nickel (Ni) and cobalt (Co) and tungsten (W) are interposed between the wiring conductor and the circuit conductor of the present invention. , Molybdenum (M
o) In the case where a metal mainly composed of at least one alloy is interposed, the increase rate of the electric resistance is as small as 31.6% or less, the wiring conductor and the circuit conductor are in close contact, and both electric conductors are It turns out that it has become very excellent.

(Effect of the Invention) According to the circuit board of the present invention, at least one of nickel (Ni) and cobalt (Co) and at least one of tungsten (W) and molybdenum (Mo) are provided between the wiring conductor and the circuit conductor. Since a metal having an alloy as a main component is interposed, the wiring conductor and the circuit conductor can be adhered with good electrical continuity and good adhesion therebetween. It is extremely useful as a circuit board.

[Brief description of the drawings]

FIG. 1 is a partially enlarged sectional view for explaining a circuit board of the present invention. DESCRIPTION OF SYMBOLS 1 ... Insulating base, 2 ... Wiring conductor 3 ... Intermediate metal layer, 4 ... Circuit conductor

Claims (3)

(57) [Claims] 1. An insulating substrate provided with a wiring conductor made of at least one of tungsten, molybdenum, and manganese,
The wiring conductor is formed in a different pattern from the wiring conductor on the outer surface of the insulating base by applying and baking a copper paste, and a part of the circuit conductor is made of copper in contact with the wiring conductor. A circuit board comprising an intermediate metal layer mainly containing an alloy of at least one of nickel and cobalt and at least one of tungsten and molybdenum between contact portions with a circuit conductor. 2. The intermediate metal layer according to claim 1, wherein the weight of at least one of tungsten and molybdenum is 2.0 to 50.0% with respect to the weight of at least one of nickel and cobalt. The described circuit board. 3. The intermediate metal layer has a thickness of 0.1 to 10.0 μm.
2. The circuit board according to claim 1, wherein: