JPH06177507A - Circuit board manufacturing method - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a method for manufacturing a circuit board, which can eliminate etching defects, make the dimensions and shapes of the circuit more precise, and also make the bonding strength high. [Structure] A composite brazing material in which a thin plate of an active metal brazing is clad on a Cu plate is half-etched from the thin plate side of the active metal brazing to form a circuit pattern, and then the composite brazing material having this circuit pattern is formed into a circuit pattern. A method for manufacturing a circuit board, characterized in that the circuit board is joined to the ceramic board on the side, and then a circuit is formed by etching from the Cu plate side of the composite brazing material in the same pattern as the circuit pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a circuit board incorporated in an inverter used in a high power power supply circuit.

[0002]

2. Description of the Related Art Conventionally, the manufacturing of the above-mentioned circuit board has been performed with reference to FIG.
As shown in FIG. 6, a paste solder 2 of an active metal is screen-printed on a ceramic substrate 1 to form a pattern, and then a Cu plate 3 is joined as shown in FIG.
A resist is applied, a pattern is formed, and etching is performed to form a circuit 4 as shown in FIG. 7 to form a circuit board 5.

By the way, in such a method for manufacturing a circuit board, an active metal paste solder 2 is formed on the ceramic substrate 1.
It takes a lot of time and effort to form a pattern by screen-printing, which is inefficient. That is, it takes a lot of time and labor from the preparation of the paste wax 2 to the screen printing, drying and brazing, and the productivity is poor. After the Cu plate 3 is brazed to the formed brazing pattern,
Since the Cu plate 3 is etched to form the circuit 4,
The brazing pattern and the circuit 4 were misaligned, the bonding strength of the circuit 4 was insufficient, and the dimensional accuracy of the circuit 4 was poor.

From the above, the inventors of the present invention, as a method for efficiently manufacturing a circuit board having high circuit bonding strength and dimensional accuracy, as shown in FIG. A composite brazing material 8 clad with a brazing thin plate 7 is joined on the active metal brazing thin plate 7 side, and after applying a resist to form a pattern, the composite brazing material 8 is etched to form a circuit 9 as shown in FIG. , A method of obtaining the circuit board 10 has been developed. However, in the method of manufacturing this circuit board, the side surface of the etched circuit 9 is dented in an arc shape,
The size and shape deteriorate. Etching residue is likely to occur, leading to defective conduction. A hydrofluoric acid-based etchant that can etch both Cu and active metal brazes is needed, but is dangerous.

[0005]

Therefore, the present invention is to provide a method of manufacturing a circuit board which can eliminate etching defects, and can make the dimensions and shape of the circuit more precise and the joint strength high. To do.

[0006]

A method for manufacturing a circuit board according to the present invention for solving the above-mentioned problems is a half-etching from a thin plate side of an active metal solder of a composite brazing material in which a thin plate of an active metal solder is clad on a Cu plate. After processing, a circuit pattern is formed, then the composite brazing material having the circuit pattern formed thereon is joined to the ceramic substrate on the circuit pattern side, and then the Cu plate side of the composite brazing material is etched in the same pattern as the circuit pattern. It is characterized by being processed to form a circuit.

[0007]

As described above, the circuit board manufacturing method of the present invention is
Since a circuit pattern is formed by half-etching from the active metal brazing thin plate side of a composite brazing material in which a thin plate of active metal brazing is clad on a Cu plate, it is not necessary as a circuit when joining the brazing compound brazing material to a ceramic substrate. The active metal wax is removed. Therefore, the etching process for forming the circuit after joining the composite brazing material having the circuit pattern to the ceramic substrate on the circuit pattern side is performed only on the Cu portion, and ferric chloride solution that is easy to handle can be used as the etching solution.
In addition, since the unnecessary brazing material as a circuit is removed in advance before joining the composite brazing material to the ceramic substrate as described above, it is possible to prevent the compound formation of the ceramic and the brazing material,
Continuity failure is eliminated, and the circuit size and shape can maintain high accuracy during etching processing before joining the composite brazing material to the ceramic substrate, and also provide high joining strength. The clad composite brazing material is not limited to two layers and may be a multi-layer composite brazing material such as three layers.

[0008]

EXAMPLE An example of a method of manufacturing a circuit board according to the present invention will be described. The thickness is 0.3 mm, the width is 30 mm, and the length is 5 mm shown in FIG.
A 0 mm Cu plate 6 with a thickness of 0.05 mm, a width of 30 mm and a length of 50 mm
Active metal brazing sheet consisting of g70% Cu28% Ti2% 7
As shown in FIG. 2, half-etching is performed from the side of the active metal brazing thin plate 7 of the composite brazing material 8 in which the clad is clad with an etching solution containing 50% ferric chloride and 50% water to form the circuit pattern 11. Then, the composite brazing material 8'on which the circuit pattern 11 is formed is formed on the circuit pattern 11 side on the AlN ceramic substrate 1 having a thickness of 0.5 mm, a width of 30 mm and a length of 50 mm as shown in FIG. 810 ℃ in a vacuum furnace at 10 ^-5 Torr,
Bonding for 5 minutes, then Cu plate 6 of composite brazing material 8 '
Ferric chloride with the same pattern as the circuit pattern 11 from the side
An etching process was performed using an etching solution composed of 50% and 50% water to form a circuit 12 as shown in FIG. 4, and a circuit board 13 was obtained.

As can be seen in this embodiment, the Cu plate 6 is made of Ag70.
% -Cu28% -Ti2% of the active metal brazing thin plate 7 of the composite brazing material 8 clad from the thin plate 7 side was half-etched to form the circuit pattern 11.
When the was bonded to the ceramic substrate 1, the active metal solder unnecessary for the circuit was removed. Therefore, the circuit pattern 11
After bonding the composite brazing material 8'formed with the circuit pattern 11 side to the ceramic substrate 1, the etching process for forming the circuit was only the Cu portion, and the etching solution was ferric chloride solution, which was easy to handle. . Further, as described above, since the unnecessary brazing material as a circuit is previously removed before joining the composite brazing material 8 ′ to the ceramic substrate 1, it is possible to prevent the compound formation of the ceramic and the brazing material, and to eliminate the conduction failure.
In addition, the size and shape of the circuit 12 can maintain high accuracy during the etching process before joining the composite brazing material 8'to the ceramic substrate 1 and also provide high joining strength. The composite brazing material 8 of the above-mentioned embodiment has two layers of Cu and an active metal brazing material, but may have three layers or four layers.

[0010]

As described above, according to the method of manufacturing a circuit board of the present invention, it is possible to obtain a circuit board which has no etching defects, can be made more precise in circuit size and shape, and has a high bonding strength. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing steps of an embodiment of a method for manufacturing a circuit board of the present invention.

FIG. 2 is a diagram showing steps of an embodiment of a method for manufacturing a circuit board of the present invention.

FIG. 3 is a diagram showing steps of an embodiment of a method for manufacturing a circuit board of the present invention.

FIG. 4 is a diagram showing steps of an embodiment of a method for manufacturing a circuit board of the present invention.

FIG. 5 is a diagram showing steps of a conventional method for manufacturing a circuit board.

FIG. 6 is a diagram showing steps of a conventional method for manufacturing a circuit board.

FIG. 7 is a diagram showing steps of a conventional method for manufacturing a circuit board.

FIG. 8 is a diagram showing steps of an improved method for manufacturing a circuit board.

FIG. 9 is a diagram showing steps of an improved method for manufacturing a circuit board.

[Explanation of symbols]

 1 Ceramic Substrate 6 Cu Plate 7 Thin Plate of Active Metal Solder 8 Composite Brazing Material 8'Composite Brazing Material Forming Circuit Pattern 11 Circuit Pattern 12 Circuit 13 Circuit Board

Claims (1)

[Claims] 1. A composite brazing material having a Cu plate clad with a thin plate of an active metal brazing material is half-etched from the thin plate side of the active metal brazing material to form a circuit pattern, and then a composite brazing material having this circuit pattern is formed. A method of manufacturing a circuit board, which comprises bonding to a ceramics substrate on the side of the circuit pattern, and then forming a circuit by etching the Cu plate side of the composite brazing material in the same pattern as the circuit pattern.