JPH04372191A - Circuit board - Google Patents

Abstract

PURPOSE:To provide a circuit board, in which the electrical conduction of a wiring conductor and a circuit conductor is improved and the conductors can be attached. CONSTITUTION:A circuit conductor 3 composed of a metal mainly comprising silver-palladium is attached onto the external surface of an insulating base body 1, to which a wiring conductor 2 consisting of at least one kind of tungsten, molybdenum and manganese is formed, so that one part of the circuit conductor is brought into contact with the wiring conductor 2. The circuit conductor 3, on a surface of which there is no oxide film, can be attached to the wiring conductor 2 while extremely improving electrical conduction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in circuit boards used in hybrid integrated circuit devices and the like.

0002

2. Description of the Related Art Conventionally, hybrid integrated circuit devices that are equipped with a large number of active components such as semiconductor elements and passive components such as resistors and capacitors to form a predetermined electronic circuit are usually
A circuit conductor made of copper (Cu) is placed on the outer surface of an insulating base in which a wiring conductor made of a high-melting point metal such as tungsten (W), molybdenum (Mo), or manganese (Mn) is embedded. A circuit board is prepared with a structure in which it is connected to the circuit board, and then semiconductor elements, capacitors, resistors, etc. are placed on the surface of the circuit board, and each electrode terminal is soldered (Sn) to the circuit conductor. -Pb alloy)
It is formed by joining via etc.

[0003] The circuit boards used in such conventional hybrid integrated circuit devices are generally manufactured by employing ceramic lamination technology and thick film technology such as screen printing. Specifically, the following method is used. Produced by.

That is, ■First, alumina (Al 2 O
3), silica (SiO2), magnesia (Mg
A plurality of raw ceramic sheets are obtained by adding and mixing an organic solvent and a solvent to a ceramic raw material powder with excellent electrical insulation properties such as O), calcia (CaO), etc., and tungsten, molybdenum, A conductive paste made of powder of a high melting point metal such as manganese is printed and coated in a predetermined pattern by employing a conventional thick film technique such as screen printing.

[0005]Next, the above-mentioned green ceramic sheets are laminated to obtain a laminate, which is fired at a temperature of approximately 1500°C, and wiring conductors made of high-melting point metals such as tungsten, molybdenum, and manganese are formed inside and on the surface. Obtain an insulating substrate having the following properties.

[0006] Finally, on the outer surface of the insulating base,
Copper paste obtained by adding and mixing copper (Cu) powder with an organic solvent and a solvent is applied by a conventionally well-known screen printing method so that a part of the paste is connected to the wiring conductor, and is then placed in a neutral atmosphere (nitrogen). atmosphere), approximately 900 ℃
The copper powder is baked at a temperature of 100 mL to coat the insulating substrate and the wiring conductor to form a circuit board as a product.

[0007]

[Problems to be Solved by the Invention] However, this conventional circuit board has a circuit conductor made of copper by applying copper paste to the outer surface of an insulating base and baking it in a neutral atmosphere (nitrogen atmosphere). When obtaining a circuit board, the firing atmosphere usually contains about 7 ppm of oxygen in order to improve the burnout of the organic solvent and solvent contained in the copper paste, and it is extremely difficult to control the oxygen content. If the amount of oxygen contained is small, the amount of copper aluminate (CuAl 2 O 3 ) precipitated at the interface between the insulating substrate and the copper powder will be small, making it impossible to firmly adhere the circuit conductor to the insulating substrate.
Moreover, when the amount of oxygen contained is large, an oxide film is formed on the surface of a circuit conductor made of copper, which has the disadvantage that it is impossible to bond semiconductor elements, resistors, etc. to the circuit conductor via solder.

[0008]

[Means for Solving the Problems] The present invention provides tungsten,
A circuit conductor made of a metal mainly composed of silver-palladium is coated on the outer surface of an insulating substrate provided with a wiring conductor made of at least one of molybdenum and manganese, with a part of the circuit conductor being in contact with the wiring conductor. It is characterized by the fact that

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained in detail with reference to the accompanying drawings. FIG. 1 is a partially enlarged sectional view for explaining the 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 an electrically insulating material such as alumina ceramics, and is made of an electrically insulating material such as alumina ceramics.
2 O 3 ), silica (SiO2), magnesia (MgO), calcia (CaO), and other ceramic raw material powders are mixed with organic solvents to form a slurry, which is then processed into ceramics using a doctor blade method. A raw ceramic sheet is obtained, and then a plurality of ceramic raw sheets are laminated together with appropriate perforations, and then fired at a temperature of about 1500° C. in a reducing atmosphere.

Further, the insulating substrate 1 is provided with a wiring conductor 2 leading out from the inside thereof to the upper surface, and the wiring conductor 2
is made of at least one of tungsten, molybdenum, and manganese.

The wiring conductor 2 is made by adding and mixing an organic solvent and a solvent to powders of tungsten, molybdenum, and manganese to make a conductor paste, and printing the conductor paste in a predetermined pattern on the upper and lower surfaces of the green ceramic sheet by screen printing or the like. By applying it, it is deposited on the inside and surface of the insulating substrate 1.

[0013] If the exposed outer surface of the wiring conductor 2 is coated with nickel (Ni), gold (Au), etc. by a plating method, electrical continuity between the wiring conductor 2 and a circuit conductor 3, which will be described later, is established. can be made extremely superior. Therefore, the exposed outer surface of the wiring conductor 2 is plated with nickel to a thickness of 1.0 to 10.0 μm and gold to a thickness of 0.5 to 5.0 μm to ensure good electrical continuity with the circuit conductor 2. It is preferable to form layers.

Further, the surface of the insulating substrate 1 including the exposed outer surface of the wiring conductor 2 is coated with silver-palladium (Ag-Pd).
A circuit conductor 3 made of a metal whose main component is .

The circuit conductor 3 is made by adding and mixing glass powder and an organic solvent to a powder of silver, palladium, etc. to make a metal paste, and making a part of the metal paste into contact with the wiring conductor 2. The insulating substrate 1 is printed and coated on the outer surface of the insulating substrate 1 and fired at a temperature of about 850° C. in a neutral atmosphere, thereby depositing silver-palladium powder on the surface of the insulating substrate 1 through the glass.
coated on the outer surface of the In this case, since palladium has the effect of suppressing oxidation, an oxide film is not formed on the surface of the circuit conductor 3 made of a metal mainly composed of silver and palladium even if the firing atmosphere contains a large amount of oxygen. As a result, it becomes possible to firmly bond semiconductor elements, resistors, etc. to the circuit conductor 3 through solder.

Further, the circuit conductor 3 made of a metal mainly composed of silver and palladium is connected to the insulating substrate 1 through glass.
Since it is adhered to the outer surface of the sintering atmosphere, the adhesion strength can always be strong regardless of the amount of oxygen contained in the firing atmosphere.

The circuit conductor 3 made of a metal mainly composed of silver-palladium contains 50 to 80% by weight of silver,
It contains 3 to 25% by weight of palladium, and when the palladium content is less than 3% by weight, an oxide film is formed on the surface of the circuit conductor 3 and a semiconductor element etc. is firmly bonded to the circuit conductor 3 through solder. At the same time, silver migration occurs in the circuit conductors 3, and there is a risk that adjacent circuit conductors 3 may be electrically short-circuited and lose their function as a circuit board. Furthermore, if the palladium content exceeds 25% by weight, the electrical resistance of the circuit tends to increase, making it unsuitable as a circuit board. Therefore, it is preferable that the circuit conductor 3 contains 50 to 80% by weight of silver and 3 to 25% by weight of palladium.

Further, the glass contained in the circuit conductor 3 may be, for example, PbO, B 2 O 3 , SiO 2 ,
Al2O3, Na2O, K2O, Ca
If the amount added is less than 0.2% by weight, it becomes difficult to firmly adhere the circuit conductor 3 to the insulating substrate 1, and if it exceeds 8.0% by weight, the circuit conductor 3 The solder wettability (reactivity) of the circuit conductor 3 deteriorates, making it difficult to firmly bond semiconductor elements, resistors, etc. to the circuit conductor 3 through solder. Therefore, the amount of glass added to the circuit conductor 3 is 0.2 to 8.0.
It is preferable to keep it in the range of % by weight.

Thus, this circuit board has semiconductor elements, resistors, capacitors, etc. placed on its surface, and by bonding the semiconductor elements, etc. to circuit conductors via solder, it becomes a hybrid integrated circuit device.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, metal paste containing silver and palladium powder When the circuit conductor 3 is formed by printing and coating on the insulating substrate 1 , by containing 2.5 to 25% by weight of bismuth, the adhesion strength of the circuit conductor 3 to the insulating substrate 1 becomes stronger.

Further, if a coating layer made of gold (Au) is deposited on the outer surface of the circuit conductor 3 to a thickness of 0.1 to 5.0 μm, oxidation corrosion of the circuit conductor 3 can be effectively prevented, and the semiconductor Electrode terminals of elements, resistors, capacitors, etc. can be more firmly connected to the circuit conductor 3.

[0022]

Effects of the Invention According to the circuit board of the present invention, since the circuit conductor is formed of a metal containing silver-palladium as a main component, when the circuit conductor is attached to the surface of the insulating substrate 1, the sintering atmosphere contains Regardless of whether the amount of oxygen absorbed is large or small, it is possible to firmly adhere a circuit conductor with no oxide film on the surface to the outer surface of an insulating substrate. It is extremely useful as a

[Brief explanation of the drawing]

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

[Explanation of symbols]

1... Insulating base 2... Wiring conductor 3...Circuit conductor 4...Covering layer

Claims (2)

[Claims] 1. A circuit conductor made of a metal containing silver-palladium as a main component is provided on the outer surface of an insulating substrate provided with a wiring conductor made of at least one of tungsten, molybdenum, and manganese, a part of which is the wiring conductor. A circuit board characterized in that the circuit board is attached in a contacting manner. 2. The circuit conductor made of a metal containing silver-palladium as a main component is made of silver and palladium powder containing 0.2 to 8.0% by weight of a glass component. The circuit board described in Item 1.