JPH11284335A - Metal-based circuit board and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal-based circuit board with no defective insulating layer or circuit and small number of burrs without using a protective film. SOLUTION: A metal-based circuit board is manufactured from a raw base board 10 by using a press die 9 with a punch 5. The punch has a blade width 0.4 or more times the metal thickness. In a metal-based circuit board separated from the raw base board 10 using the press die 9 having the punch 5 with the blade width 0.4 or more times the thickness of the raw base board 10, an inner circuit is at a distance 0.5 to 1.6 times the metal thickness from the outer edge of the metal-based circuit board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-based circuit board for mounting a semiconductor used in electric equipment, communication equipment, automobiles and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Circuit boards on which semiconductor elements and various electric components are mounted are known in a wide range of fields such as electric equipment, communication equipment, and automobiles. However, metal bases are inexpensive and have excellent heat dissipation. Circuit boards have attracted attention and are being used.

A metal-based circuit board has a structure in which a circuit is provided on one main surface of a metal plate excellent in heat dissipation through an insulating layer, and iron and aluminum are often used for the metal plate. The insulating layer is made of a resin such as an epoxy resin containing an inorganic filler such as aluminum oxide, and the circuit is formed of various metal foils, usually made of copper, aluminum, or a composite material of copper and aluminum. It is heavily used.

The above-mentioned metal-based circuit board is generally produced in large quantities by dividing a metal-based circuit board base plate on which a plurality of metal-based circuit boards are imposed into individual pieces. A method of punching with a press die is generally used.

However, in the punching method using a press die, the punch may come into contact with the conductor circuit due to the flat punching surface at the bottom of the punch of the press die. Scratches and indentations were generated, the function of the insulating layer was impaired, and the insulation performance of the circuit board was sometimes reduced. The deterioration of the insulation performance causes serious problems that the reliability of the circuit board is lowered and that the circuit board cannot be used at a high voltage.

For the purpose of solving the above problems, in reality, a protective film is stuck on the surface of a punched substrate (original plate) to cushion the impact at the time of punching, thereby preventing scratches and indentations. However, in this method, as the thickness of the protective film increases, the burrs on the outer peripheral edge of the circuit board increase,
When transporting or storing circuit boards while contacting them,
The burrs damage the conductor circuits of other circuit boards,
Problems such as destruction may occur.

Further, with respect to a metal base circuit board for use in a large current, the punch of the press mold and the metal base circuit board are required when punching with a press mold because the thickness of the conductor circuit is large due to the limitation of the use. There is a gap between
An irregularity may occur in the pressure applied to the metal base circuit board, causing an abnormality such as warpage or distortion on the back surface of the metal base circuit board or chipping of the insulating layer near the outer peripheral edge.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to attach a metal foil to a metal plate via an insulating layer to form a plurality of circuit boards. A press die having a punch die of a specific shape when dividing each circuit board from a metal base circuit board base plate imposed, and having a punch formed with a depression so that the bottom does not contact the conductive circuit By using, scratches,
An object of the present invention is to provide a metal-based circuit board that prevents indentation and has highly reliable insulating properties.

[0009]

That is, the present invention is directed to a method of separating a circuit board from a metal base circuit board base plate having a plurality of circuits provided on a metal plate via an insulating layer with a press die. A method of manufacturing a base circuit board, wherein the width of the cutting edge of the punch of the press die is 0.4 times or more the thickness of a metal plate. Has a concave portion having a depth equal to or greater than the thickness of the conductor circuit of the circuit board.

Further, the present invention provides a punch having a blade width of 0.4 times or more the thickness of a metal plate from a metal base circuit board original plate having a plurality of circuits provided on a metal plate via an insulating layer. A metal base circuit board divided into respective circuit boards by using a pressing die having a circuit, wherein a circuit is 0.5 times or more 1.6 times the metal plate thickness from the outer peripheral edge of the metal base circuit board.
A metal-based circuit board that is less than twice as far away.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

FIG. 1 is a schematic view showing an example of a metal-based circuit board of the present invention and an original plate of a metal-based circuit board used for obtaining the same. FIG. 2 shows an example of a press die used in the present invention. FIG. FIG. 3 is a schematic view of a press die used in the prior art.

As shown in a plan view of FIG. 1A and a cross-sectional view of FIG. 1B, an original metal-based circuit board used in the present invention is provided on a metal plate 1 with an insulating layer 2 interposed therebetween. A plurality of circuits 3 are provided. In general, a metal base circuit board original plate is obtained by applying an insulating layer 2 made of a resin containing an inorganic filler onto a metal plate 1, pasting a metal foil, and curing the resin layer by heating. Is manufactured by forming a plurality of circuits 3 by processing by a method such as etching. However, the present invention is not limited to this. Then, by punching out the above-mentioned metal base circuit board base plate with a press die, individual metal base circuit boards 4 (a plan view is shown in FIG. 1C and a sectional view is shown in FIG. 1D) are manufactured. .

The present invention is characterized in that a press die having a blade-shaped punch having a specific shape is used for punching with the above press die. FIG. 2 illustrates a press die used in the present invention. The press die 9 comprises a punch 5 and a die 6 having a space for accommodating at least a part of the punch. Generally, the die 6 is set on the fixed lower die set 13, and the metal base circuit board original plate is placed at a predetermined position on the die 6, and the die 6 is fixed to the vertically movable die set 11. The punch 5 is performed by moving the punch 5. In the present invention, it is essential that the width of the blade die 7 of the punch 5 is 0.4 times or more the thickness of the metal plate 1 of the blank metal base circuit board. Also, as a preferred embodiment,
The punch 5 has a concave portion 8 having a depth greater than the thickness of the circuit 3. In FIG. 2, the plate retainer 12 is
Although not shown, the upper die set 1 is connected via a spring.
Fixed to 1.

According to the study by the present inventors, the width of the blade mold 7 is closely related to the thickness of the metal plate with respect to the optimum value. Since the stress load per area is increased, indentations are formed on the metal base circuit board 4 and the appearance may be impaired, or in severe cases, the insulating layer 2 may be damaged, resulting in poor electrical properties such as insulation resistance. On the other hand, there is no technical reason to limit the upper limit of the width of the blade 7. However, if the upper limit is too large, the upper limit is usually about 1.5 times because the contact with the circuit 3 may damage the circuit 3. Further, when the thickness is 0.7 times or more the thickness of the metal plate 1 and 0.2 to 0.5 mm smaller than the distance between the outer peripheral edge of the circuit board and the surface of the circuit 3,
This is preferable because the height of the metal base circuit board with respect to the metal base circuit board original plate can be increased without causing the above-described problem.

The metal-based circuit board 4 of the present invention is obtained by using the above-mentioned specific press die,
Is 0.5 metal thickness from the outer peripheral edge of the metal base circuit board.
It is characterized by being separated by 1.6 times or more. When the circuit 3 is less than 0.5 times the metal plate thickness, the stress load per unit area at the time of punching becomes large and an indentation of the punch is formed. When the circuit exceeds 1.6 times, the metal base circuit board relative to the original metal base circuit board is used. It is not preferable because the removal height becomes small. The circuit is 0.8 metal thick from the outer edge of the circuit board.
It is preferable that the width is 1.2 times and 0.2 to 0.5 mm larger than the width of the blade 7 of the punch 5.

In the present invention, the metal plate 1 may be made of aluminum, iron, copper or the like, or any of their alloys and composite materials. However, since the metal plate 1 has good heat dissipation, is inexpensive, and is lightweight, pure aluminum is used. And an aluminum alloy is preferably used. Normal plate thickness is in the range of 1.0 to 5.0 mm.

The insulating layer 2 can be made of any material having an insulating property, for example, epoxy resin,
A resin such as a phenol resin, an unsaturated polyester resin, and a polyimide resin is used. Among them, the epoxy resin is preferably selected because of its excellent adhesion to the metal plate 1 and the circuit 3. In addition to using the resin alone, the resin can be used in the form of a glass cloth, one filled with various inorganic fillers in powder form or fibrous form, or a combination thereof. Regarding the method of forming the insulating layer, the insulating layer may be applied on a metal plate, or may be provided by sticking it once as a film. Incidentally, regarding the inorganic filler, aluminum oxide, silicon oxide, aluminum nitride, silicon nitride, has a high electrical insulation such as boron nitride,
Moreover, those having high thermal conductivity are preferable.

The metal foil for the circuit 3 is a copper foil, and the copper foil is made of Ni.
Either plating or Au plating, aluminum foil, or copper foil bonded to aluminum foil can be used. In addition, as for the press die, the number of combinations of the punch 5 and the die 6 may be one or plural, and the vertical position of the punch 5 and the die 6 may be reversed, or the same die may be used. It may be a compound type with a built-in drilling function inside.

[0020]

EXAMPLES [Example] An epoxy resin containing 76% by weight of aluminum oxide was coated on an aluminum plate (thickness: 3.0 mm) so as to have a thickness of 150 μm after heat-curing, and a copper foil having a thickness of 105 μm was obtained. Were adhered, heated and cured, and then subjected to an etching process to form a circuit, thereby producing a metal-based circuit board original plate having a plurality of circuits. At this time, for each metal base circuit board, the circuit was formed such that the circuit was separated from the outer peripheral edge of the metal base circuit board by at least 3.0 mm or more.

As shown in FIG. 2, each metal base circuit board is punched and divided from the original metal base circuit board using a press die through which two metal base circuit boards are punched at a time. A blade having a width of 2.5 mm is provided on the bottom surface of each punch of the press die, and a concave portion having a depth of 0.3 mm is provided at the center of the bottom surface of the punch. The punching conditions were as follows: using a press machine manufactured by Komatsu Ltd .;
The punching speed was per minute.

With respect to the obtained 20 metal-based circuit boards, the following methods were used to evaluate the withstand voltage characteristics, the size of burrs on the outer peripheral edge, and the presence or absence of chipping of the insulating layer, scratches on the circuit, and dirt. Table 1 shows the results. The withstand voltage characteristics were obtained by measuring the withstand voltage characteristics between the circuit of the metal base circuit board and the metal plate by a step-up method (0.5 kVAC, 20 sec steps) using TOS5050 manufactured by Kikusui Electronics Co., Ltd. For burrs height, manufactured by Nissho Precision Optical Co., Ltd .;
The height of the protruding burrs generated on the outer peripheral edge of the metal base circuit board was measured using an optical step micro depth height measuring instrument. In addition, the presence or absence of a chip in the insulating layer, and the scratches and dirt on the circuit surface were visually observed. Table 1 shows the results.

[0023]

[Table 1]

COMPARATIVE EXAMPLE A first embodiment was performed except that the punch was in contact with the metal base circuit board via a protective film at the time of punching using a press die (see FIG. 3) having a flat bottom. The same evaluation as in the example was performed on 20 metal-based circuit boards obtained by the same operation as in the above. The results are shown in Table 1. In addition, as the protective sheet, a 55 μm-thick polyethylene protective film manufactured by San-A Chemical Co., Ltd. was used.

[0025]

As is clear from the above examples, according to the present invention, a metal-based circuit board having no insulation layer or circuit failure, less burrs and excellent withstand voltage characteristics can be obtained without using a protective film. It can be obtained and is extremely useful industrially.

The metal-based circuit board according to the present invention does not apply unnecessary pressure to the circuit or the insulating layer immediately below the circuit when punching with a press die. Is small, so that even when stacked and stored and transported, scratches and defects are less likely to occur on the circuit and the insulating layer, so that there is an effect that the insulation resistance, the appearance, and the reliability are high.

[Brief description of the drawings]

FIG. 1 shows a metal-based circuit board according to an embodiment of the present invention;
It is a schematic diagram of a metal base circuit board original plate to obtain it,
(A) and (b) are a plan view and a cross-sectional view of a metal base circuit board original plate, respectively, and (c) and (d) are a plan view and a cross-sectional view of the metal base circuit board, respectively.

FIGS. 2A and 2B are schematic diagrams of a press die used in an embodiment of the present invention, in which FIG. 2A shows a state in which a metal base circuit board original plate is set, and FIG.

3A and 3B are schematic diagrams of a conventionally known press die used in a comparative example, in which FIG. 3A is a diagram illustrating a state where a metal base circuit board original plate is set, and FIG. 3B is a cross-sectional view of a punch.

[Explanation of symbols]

 1: metal plate 2: insulating layer 3: circuit 4: metal base circuit board 5: punch 6: die 7: blade 8: recess 9: press die 10: metal base circuit board original plate 11: upper die set 12: plate Presser foot 13: Lower die set

Claims (3)

[Claims] 1. A method of manufacturing a metal-based circuit board, comprising: dividing each circuit board by a press die from a metal-based circuit board original plate in which a plurality of circuits are provided on a metal plate via an insulating layer; A method for manufacturing a metal-based circuit board, wherein a width of a blade of a punch of the press die is 0.4 times or more a thickness of a metal plate. 2. The method according to claim 1, wherein the punch has a recess having a depth greater than a thickness of the conductor circuit of the circuit board. 3. A press die having a punch having a blade width of 0.4 times or more the thickness of a metal plate from a metal base circuit board original plate having a plurality of circuits provided on a metal plate via an insulating layer. A metal-based circuit board divided into respective circuit boards, wherein the circuit is separated from the outer peripheral edge of the metal-based circuit board by 0.5 to 1.6 times the metal plate thickness. Features metal-based circuit boards.