JP2816742B2 - 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 plurality of active components such as semiconductor elements and passive components such as resistors and capacitors are mounted to form a predetermined electronic circuit is usually provided inside. 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. A circuit board having a structure adhered as described above is prepared, and then 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. By doing so, a hybrid integrated circuit device is obtained.

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.

That is, first, an organic solvent and a solvent are added to and mixed with a ceramic raw material powder having excellent electrical insulation such as alumina (Al ₂ O ₃ ) to obtain a plurality of raw ceramic sheets, and the raw ceramic sheets are formed on the upper and lower surfaces of each raw ceramic sheet. A conductive paste made of a high melting point metal powder such as tungsten (W), molybdenum (Mo), and manganese (Mn) is printed and applied in a predetermined pattern by employing a conventionally known thick film technique such as screen printing.

Next, the respective 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. In a neutral atmosphere (nitrogen atmosphere), this is fired at a temperature of about 800 ° C., and copper (Cu) powder is baked on an insulating substrate and a wiring conductor, and is adhered. It becomes a circuit board.

However, this conventional circuit board has poor wettability (reactivity) between tungsten (W), molybdenum (Mo) or the like forming the wiring conductor and copper (Cu) forming the circuit conductor. Even when a circuit conductor is partially formed, 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.

In view of the above drawbacks, tungsten (W) and molybdenum (Mo), which form the wiring conductor, and copper (C), which forms the circuit conductor, are formed on the outer surface of the wiring conductor where the circuit conductor contacts.
u) Nickel (N
A circuit board has been proposed in which a coating layer made of i), cobalt (Co), or the like is adhered to thereby improve the adhesion between the wiring conductor and the circuit conductor (Japanese Patent Application Laid-Open (JP-A) No. 2002-143873).
58-30194).

However, when this circuit board is applied by baking the circuit conductor on the wiring conductor with a coating layer interposed therebetween, copper (Cu) forming the circuit conductor and nickel (Ni), cobalt ( Inter-diffusion occurs between the copper and copper (Co), etc., and part of the copper (Cu) in the circuit conductor directly contacts the wiring conductor made of tungsten (W), molybdenum (Mo), etc., which has poor wettability (reactivity). Adhesion between the wiring conductor and the circuit conductor deteriorates, and when thermal stress such as a temperature cycle is applied to the circuit conductor and the wiring conductor, peeling occurs due to a difference in thermal expansion coefficient between the two. However, as a result, there is a disadvantage that the electrical conduction between the circuit conductor and the wiring conductor is greatly deteriorated.

(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) The present invention provides a circuit conductor made of copper on an outer surface of an insulating base provided with a wiring conductor made of at least one of tungsten, molybdenum, and manganese, and a part of the circuit conductor comes into contact with the wiring conductor. In the circuit board thus adhered, an intermediate metal mainly composed of an alloy of at least one of nickel, cobalt, tungsten, and at least one of molybdenum and boron is provided at a contact portion between the wiring conductor and the circuit conductor. It is characterized in that a layer is 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 ), magnesia (MgO), calcia (CaO) and other ceramic raw material powders are mixed with an organic solvent and a solvent to form a slurry. Thereafter, the ceramic green sheet is manufactured by subjecting the green ceramic sheet to appropriate perforation processing, laminating a plurality of sheets, and firing at 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 printing and applying a predetermined pattern by the method described above, the insulating substrate 1 is adhered and formed inside and on the surface.

The wiring conductor 2 is provided with nickel (Ni), cobalt (C)
o), an intermediate metal layer 3 made of a metal mainly containing an alloy of at least one of tungsten (W) and molybdenum (Mo) and boron;
The intermediate metal layer 3 is formed on the exposed outer surface of the wiring conductor 2 by electroplating, electroless plating, or the like.

The intermediate metal layer 3 is made of a metal constituting the wiring conductor 2, that is, an alloy of at least one of nickel (Ni) and cobalt (Co) with tungsten (W) and at least one of molybdenum (Mo) and boron. And the circuit conductor 4 have good wettability (reactivity), and when the circuit wiring 4 is applied on the wiring conductor 2, the two are completely adhered to each other and the electrical conduction between them is extremely excellent. Do

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 extremely 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.
A part of the metal tends to diffuse in the intermediate metal layer 3 and directly contact the wiring conductor 2 to deteriorate the adhesion between the wiring conductor 2 and the circuit conductor 4. In addition, tungsten (W), molybdenum (Mo)
If the total weight exceeds 50.0% of 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 connected to the wiring conductor. Since the intermediate metal layer 3 tends to be unable to adhere with good adhesion, the total weight of the tungsten (W) and molybdenum (Mo) is based on the total weight of nickel (Ni) and cobalt (Co) of 100. It is desirable to set it in the range of 2.0 to 50.0%.

The boron (B) contained in the intermediate metal layer 3 has an effect of suppressing the formation of an oxide film on the surface of the intermediate metal layer 3 and improving the adhesion between the intermediate metal layer 3 and the circuit conductor 4. If the content is less than 0.1% by weight, the above properties do not work effectively. If the content exceeds 3.0% by weight, the intermediate metal layer 3 becomes hard and brittle, and cracks when heat stress such as temperature cycle is applied. And the electrical continuity between the wiring conductor 2 and the circuit conductor 4 tends to deteriorate. Therefore, the intermediate metal layer 3
It is desirable that the content of boron (B) is set in the range of 0.1 to 3.0% by weight.

Further, if the thickness of the intermediate metal layer 3 is less than 0.1 μm, the diffusion of copper (Cu) forming the circuit conductor 4 cannot be completely prevented, and a part of the circuit conductor 4
And tends to degrade the adhesion between the wiring conductor 2 and the circuit conductor 4 by direct contact with the wiring conductor 2.
Is exceeded, a crack occurs due to internal stress in the intermediate metal layer 3, and a part of the circuit conductor 4 directly contacts the wiring conductor 2 through the crack in the intermediate metal layer 3, and the wiring conductor 2 and the circuit conductor 4
The intermediate metal layer 3
Is preferably in the range of 0.1 to 10.0 μm.

A circuit conductor 4 made of copper (Cu) is further attached to the surface of the insulating base 1 including the upper surface of the intermediate metal layer 3 attached to the outer surface of the wiring conductor 2. Electrodes of active components such as elements and passive components such as resistors 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 Thus, the circuit conductor 4 can be adhered with good adhesion and good electrical continuity between them.

Thus, the circuit board has a semiconductor element, a resistor, a capacitor, and the like mounted and attached on the surface thereof, and each electrode of the semiconductor element and the like is connected to a circuit conductor to form a hybrid integrated circuit device.

(Experimental Example) Next, the operation and effect of the present invention will be described based on an experimental example 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 about 1500 ° C. in a reducing atmosphere to form a wiring conductor made of the material shown in Table 1 on an insulating substrate 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 wire conductors, and is printed in a neutral atmosphere.
Baking at a temperature of 800 ° C 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 value between the pair of wiring conductors and the electric resistance value after 100 cycles of a temperature cycle test of -65 to + 150 ° C are measured, and the rate of change (increase rate) is obtained 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 Nos. 29 and 30 are comparative samples for comparison with the product 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. In this case, mutual diffusion 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, whereas nickel (Ni), cobalt (C)
o) interposed a metal whose main component is an alloy of at least one of tungsten (W) and molybdenum (Mo) and boron and has a small increase rate of electric resistance of 12.5% or less, and the wiring conductor It can be seen that the circuit conductors are in close contact with each other, and the electrical conduction between the two is extremely 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 mainly composed of an alloy of a seed and boron (B) is interposed, the wiring conductor and the circuit conductor can be adhered with good electrical continuity between them,
It is extremely useful as a circuit board used for a hybrid integrated circuit device or the like.

[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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H05K 3/46 H05K 1/09 H05K 3/10-3 / 26,3 / 38

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 comes into contact with the wiring conductor. A circuit board, wherein an intermediate metal layer mainly containing an alloy of at least one of nickel and cobalt, tungsten, and at least one of molybdenum and boron is interposed at a contact portion between the wiring conductor and the circuit conductor. The intermediate metal layer has a boron content of 0.1 to
A circuit board, wherein the weight is 3.0% by weight, and the weight of tungsten and molybdenum is 2.0 to 50% with respect to the weight of 100 of nickel and cobalt.