JPS5835374B2 - Method for manufacturing hybrid integrated circuits - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing a hybrid integrated circuit.

Japanese Patent Publication No. 46-13234 has already proposed a hybrid integrated circuit board in which an oxide film is formed by anodizing the surface of an aluminum substrate.

Since such a hybrid integrated circuit board has good thermal conductivity, it is possible to realize a hybrid integrated circuit with good heat dissipation and high output.

However, the electrical insulation of such a board mainly depends on the oxide film, so if a crack occurs in the oxide film, moisture or flux from the soldering process may enter the crack and form on the board. There is a risk that a leakage current may be generated between the circuit components and the aluminum substrate, or in the worst case, a short circuit may occur.

The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to provide a method for manufacturing a hybrid integrated circuit with good insulation.

An embodiment of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, a hybrid integrated circuit board 3 is prepared by forming an oxide film 2 on the surface of a metal plate 1 made of aluminum or the like with good thermal conductivity by anodizing.

The oxide film 2, for example, alumina, is prone to cracking due to the difference in coefficient of thermal expansion between the oxide film 2 and the metal plate 1.

A copper foil 4 serving as a conductive path is bonded to one main surface of the hybrid integrated circuit board 3, and a nickel plating layer 5 is formed on the surface of the copper foil 4 to protect the surface.

In such a hybrid integrated circuit board 3, a copper foil 4 is etched to form a predetermined conductive path, as shown in FIG. Selectively removed.

A conductive paint and a resistive paint are then screen printed onto the predetermined portions, and the respective paints are fired to form the conductor 6 and the resistor 7.

Firing is carried out at 200° C. for 6 hours.

Cracks 8 are most likely to occur in the oxide film 2 during this firing step, and since there is no such long heating step in subsequent steps, new cracks will not occur.

Moreover, the moisture inside the crack 8 can also be removed in this step.

The feature of the present invention is that, as shown in FIG. 4, cracks 8 generated in the oxide film 2 are impregnated with a liquid insulating material 9 such as silicone oil.

The crack 8 described above is extremely small, but by using the liquid insulator 9, it can be easily injected into the entire crack 8 by capillary action. It can be fixed by

The impregnation with the liquid insulator 9 is carried out at room temperature for 10
This is carried out by immersing a large number of hybrid integrated circuit boards 3 in a container 21 containing liquid insulator 9 placed in a reduced pressure container 20 of about mHf for about two hours.

According to this vacuum impregnation method, the air within the crack 8 can be completely excluded, and the crack 8 can be completely filled with the liquid insulating material 9.

After the impregnation process has been completed, the hybrid integrated circuit board 3 is cleaned with an organic solvent to remove the liquid insulator 9 adhering to its surface, leaving the liquid insulator 9 only in the cracks 8 by capillary action and fixing it.

Thereafter, as shown in FIG. 4, solder cream is screen printed on the copper foil 4 and heated to adhere the solder layer 10.

Due to this heating, the flux contained in the solder cream scatters, but cannot penetrate into the crack 8 because there is a liquid insulator 9 therein.

Further, as shown in FIG. 5, a heat sink 11 is placed on the solder layer 10.
Transistor 12 is fixed via
From the second electrode, a thin lead wire 13 is fixed onto the nickel plating layer 5 by ultrasonic vibration to establish an electrical connection.

As described in detail above, according to the present invention, since the crack is impregnated with a liquid insulator before the solder adhesion process, flux does not penetrate into the crack at all and extremely good insulation can be obtained.

In addition, by performing the impregnation process after firing the conductor layer and resistor, water in the cracks is removed and cracks are generated in advance, allowing the liquid insulator to be impregnated into all cracks that occur, achieving complete insulation. can.

Further, the vacuum impregnation method allows liquid insulation to be completely and easily injected into any microscopic rack, and more perfect insulation can be obtained.

[Brief explanation of the drawing]

1 to 5 are cross-sectional views for explaining the present invention, and FIG. 6 is a cross-sectional view for explaining the impregnation method used in the present invention. 1 is a metal plate, 2 is an oxide film, 3 is a hybrid integrated circuit board, 4 is a copper foil, 5 is a nickel plating layer, 6 is a conductor, 7 is a resistor,
8 is a crack, 9 is a liquid insulator, 10 is a solder layer, 11 is a heat sink, 12 is a transistor, and 13 is a thin lead wire.

Claims (1)

[Scope of Claims] 1. A hybrid integrated circuit in which a hybrid integrated circuit board is prepared by forming an oxide film by anodization on the surface of a metal plate with good thermal conductivity, and a conductive resistor layer and circuit components such as transistors are provided on the board. In the method of manufacturing a hybrid integrated circuit, the oxide film of the hybrid integrated circuit board is impregnated with a liquid insulating material into cracks generated in a previous heating step before the step of attaching solder. Method. 2. A method for manufacturing a hybrid integrated circuit in which a hybrid integrated circuit board is prepared by forming an oxide film on the surface of a metal plate with good thermal conductivity by anodization, and circuit components such as a conductive resistor layer and transistors are provided on the board. , the hybrid integrated circuit board is placed in a liquid insulator before the process of attaching solder, and the liquid substance is impregnated into the cracks generated in the oxide film during the previous heating process under reduced pressure. A method for manufacturing hybrid integrated circuits. 3. A method for manufacturing a hybrid integrated circuit, in which a hybrid integrated circuit board is prepared by forming an oxide film on the surface of a metal plate with good thermal conductivity by anodization, and circuit components such as a conductive resistor layer and transistors are provided on the board. A method for manufacturing a hybrid integrated circuit, comprising impregnating a liquid insulator into cracks generated in the oxide film after the step of firing the conductor button and the resistor and before the step of attaching solder. 4. A method for manufacturing a hybrid integrated circuit, in which a hybrid integrated circuit board is prepared by forming an oxide film by anodization on the surface of a metal plate with good thermal conductivity, and circuit components such as a conductive resistor layer and transistors are provided on the board. After the step of firing the conductor and resistor and before the step of attaching solder, the hybrid integrated circuit board is placed in a liquid insulator, and the cracks generated in the oxide film are impregnated with the liquid insulator under reduced pressure. A method for manufacturing a hybrid integrated circuit, characterized in that: