JPH0259638B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a hybrid integrated circuit, and particularly to a hybrid integrated circuit having a resistor that is stable at high temperatures.

(b) Prior Art A conventional hybrid integrated circuit is shown in FIG. The hybrid integrated circuit board 1 is made of an aluminum substrate whose surface has been anodized. Conductive paths 2 made of copper foil in a desired shape are provided on the substrate 1, and printed resistors 3 or nickel-plated resistors 4 are appropriately placed between the conductive paths 2. Formed.

Since such a hybrid integrated circuit board 1 has good heat dissipation properties, it is possible to incorporate a resistor that consumes a large amount of power, and in particular, it is possible to incorporate a nickel-plated resistor for high power.

The printed resistor 3 is formed by screen printing and firing an epoxy resin-based carbon printed resistor paste, and is significant in that a wide range of resistance values can be achieved by screen printing. However, since the epoxy resin has poor heat resistance, there is a drawback that the resistance value fluctuates widely.

The nickel-plated resistor 4 is formed by electroless plating of nickel to a thickness of about 2 to 3 μm, and is used as a high-power resistor of 5Ω or less. Although considerable heat is generated during use, the heat is dissipated more efficiently than the hybrid integrated circuit board 1.

However, in the hybrid integrated circuit described above, the resistance value of the printed resistor 3 fluctuates widely, as shown by the dotted line in FIG. 3, as is clear from the high temperature storage test at 150°C. For this purpose, the temperature of the Nickel-metsuki resistor 4 is 150℃.
Despite its durability, it has not been possible to increase the withstand temperature of hybrid integrated circuits to 150°C, and it has not been possible to realize hybrid integrated circuits for applications with strict specifications such as automotive electrical equipment or power supplies.

Further, in order to solve the above-mentioned problems, it is possible to use a printing paste based on a polyimide resin having excellent heat resistance.

There are two types of polyimide resins: Kapton type and bismaleimide type. Kapton type is a thermoplastic polyimide that dissolves only in highly polar solvents such as dimethylformamide and N-methylpyrrolidone, and bismaleimide type is a more diverse type of polyimide than these. It is a thermosetting polyimide that can be dissolved even in solvents with weak polarity.

However, the Kapton type is extremely difficult to paste and requires strong polar solvents that are harmful to the printed stencil. Furthermore, it requires baking at a high temperature of 250℃ or higher for a long time. Furthermore, although the bismaleimide type is relatively easy to form into a paste with carbon, it requires a strong polar solvent and baking at a high temperature of 250° C. or higher for a long period of time, similar to the Kapton type described above. Furthermore, due to brittleness and low adhesion, which are the drawbacks of the bismaleimide type, the biggest drawback is that it is not only impossible to uniformly screen print a film with a thickness of less than 20 μm, but also that a structurally stable thick film resistor cannot be obtained. Ta.

Therefore, printing pastes based on polyimide resins, which have excellent heat resistance, cannot be actively used.

(c) Purpose of the Invention The present invention has been made in view of the above, and aims to eliminate the conventional drawbacks and realize a hybrid integrated circuit that can withstand temperatures of 150°C.

(D) Structure of the Invention As shown in FIG. 2, the hybrid integrated circuit according to the present invention includes a hybrid integrated circuit board 11, a conductive path 12 provided on the board 11, and carbon based on an epoxy-modified thermosetting polyimide resin. A resistor 13 formed of a range printed resistor or a nickel plating resistor,
It consists of 14.

(E) Example The hybrid integrated circuit board 11 is made of an aluminum substrate whose surface is alumite-treated or whose aluminum substrate surface is coated with an insulating resin containing Al ₂ O ₃ to obtain good heat dissipation. .

A copper foil is pasted onto the substrate 11 and etched into a desired shape to form a conductive path 12. The conductive path 12 is nickel plated to prevent surface oxidation.

The nickel plating resistor 14 is formed by exposing only the portion of the surface of the substrate 11 where the resistor will be formed and covering it with a resist layer, and then immersing the entire substrate 11 in an electroless nickel plating solution made of nickel sulfide, sodium hypophosphite, etc. A nickel plated resistor 14 having a thickness of about 2 to 3 microns is formed between the conductive paths 12. Since this nickel-plated resistor 14 is a metal film resistor, it is suitable for large current and low resistance. It is mainly used as an emitter resistor for output transistors, etc. The resistance value used is in the range of 0.01Ω to 1KΩ.

The carbon resin printed resistor 13 is the most characteristic feature of the present invention, and is formed using a carbon resin printed resistor paste based on epoxy-modified polyimide resin. The above carbon resin printed resistance paste is made of epoxy modified polyimide resin 1
00, carbon 8, inorganic filler 30, organic solvent agent 110 in weight ratio. The epoxy-modified polyimide resin is formed by adding 10 to 80 parts of an epoxy resin having a molecular weight of 300 to 3,000 to a bismaleimide type polyimide resin, denaturing the resin by heating, and copolymerizing the resin. This carbon resin printed resistor paste is screen printed between the conductive paths 12 on the substrate 11 and fired. The baking time is 1 hour at 180℃, which is significantly shorter than conventional epoxy resin-based carbon resin printed resistance pastes.

The carbon resin printed resistor paste according to the present invention changes the fragility and low adhesion of bismaleimide polyimide resin into properties suitable for screen printing, such as flexibility and high adhesion, through epoxy modification, and also has the inherent heat resistance of polyimide resin. It has excellent properties of water resistance and hot water resistance.
Therefore, the carbon resin printed resistor 13 formed with such a resistor paste has the following characteristics as shown by the solid line in FIG.
As is clear from the high-temperature storage test at 150°C, it is clear that the range of resistance fluctuation can be suppressed to -10% or less, and that it can withstand satisfactorily even at 150°C. Therefore, the amount of carbon mixed in the resistor paste was adjusted to 50
A wide range of resistance values from Ω to 300KΩ can be achieved by screen printing in the same way as in the past.

Note that other circuit elements such as transistors, integrated circuits, chip capacitors, etc. are fixed on the conductive path 12 to make desired electrical connections.

(F) Effects According to the present invention, by using the carbon resin printed resistor 13 based on epoxy-modified polyimide resin, all the resistors can be given the characteristic of being durable at 150°C. As a result, the hybrid integrated circuit board 11 with good thermal conductivity overlaps with the high output circuit.
IC can be easily implemented.

Furthermore, since it is possible to create a hybrid integrated circuit that can withstand temperatures of 150°C, it can be used in applications with strict specifications that handle large amounts of power, such as automotive electrical equipment or power supplies.

Furthermore, since the carbon printing resistor paste based on epoxy-modified thermosetting polyimide resin used in the present invention can be dissolved in a weakly polar solvent, the screen printing stencil will not be dissolved by the solvent, resulting in high precision and fluctuation. Less printing resistance can be formed.

[Brief explanation of drawings]

FIG. 1 is a sectional view illustrating a conventional hybrid integrated circuit, FIG. 2 is a sectional view illustrating a hybrid integrated circuit according to the present invention, and FIG. 3 shows a carbon resin printed resistor used in the present invention and a conventional one. It is a curve diagram explaining high temperature storage characteristics to be compared. 11 is a hybrid integrated circuit board, 12 is a conductive path, 13
14 is a carbon resin printed resistor, and 14 is a nickel plating resistor.

Claims (1)

[Claims] 1. A hybrid integrated circuit in which a conductive path of a desired shape is formed on a hybrid integrated circuit board, and a low-resistance element and a high-resistance element are formed between the conductive paths, wherein the low-resistance element is a nickel-plated resistor. . A hybrid integrated circuit characterized in that the high resistance element is a carbon resin printed resistor based on an epoxy-modified thermosetting polyimide resin.