JPH0563358A - Manufacture of metal core printed wiring board - Google Patents

Abstract

PURPOSE:To make insulation of a terminal insertion hole sure by a simple process and using a small amount of insulative resin. CONSTITUTION:An insulative resin spreading tool 123 wherein a metal rod 121 whose diameter is smaller than a through hole 111 is formed so as to protrude downward is arranged above the upper side of a metal plate 11. A tank 13 filled with fused thermoplastic insulative resin 131 is arranged below the lower side of the metal plate 11. The insulative resin spreading tool 123 is made to descend to insert the metal rod 121 into the through hole 111. The tool is further made to descend to sink the tip of the metal rod 121 in the thermoplastic resin 131. Next, the tool 123 wherein the thermoplastic resin 131 adheres to the tip of the metal rod 121 as shown in (e) is made to ascend, and the tip of the metal rod 121 to which tip the thermoplastic insulative resine 131 adheres is made to pass the through hole 111. As a result, the inner surface of the through hole 111 is coated with the thermoplastic resin 131 as shown in (f). Thereby the insulation of a terminal insertion hole can easily be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a metal core printed wiring board in which an electronic circuit is formed on a metal plate,
In particular, it relates to a method of manufacturing a metal core printed wiring board capable of improving the insulation of the terminal insertion hole.

[0002]

2. Description of the Related Art In recent years, the demand for printed wiring boards has increased with the increase in density and performance of electronic devices. For example, it has a high degree of dimensional stability, a rigidity that can withstand the mounting of a large number of heavy parts, and a high degree of thermal conductivity for promptly removing heat generated from the mounted parts. In order to meet such demands, conventional substrates using organic materials such as paper phenol substrates and glass epoxy substrates cannot satisfy these demands. Therefore, metal core printed wiring boards using metal plates such as aluminum and iron as cores Has been developed and put to practical use. FIG. 6 is a cross-sectional view showing such a conventional metal core printed wiring board.

In FIG. 6, reference numeral 41 is a metal plate made of aluminum. An insulating layer 42 is formed on the upper surface of the metal plate 41, and a wiring layer 43 is formed thereon. Wiring layer 43
Chip components and power transistors are mounted on the.

In the metal core printed wiring board shown in FIG. 6, the components to be mounted are limited to leadless components, and lead components such as transformers and electrolytic capacitors cannot be used, and their applications are limited. In response to this, a metal core printed wiring board provided with a terminal insertion hole for a lead component has been developed. 7A to 7C are process diagrams showing a conventional metal core printed wiring board provided with terminal insertion holes for lead components in the order of manufacturing steps.

First, as shown in FIG. 7A, the through hole 5
A metal plate 51 on which 11 is formed is prepared. In FIG. 7B, an insulating resin 53 (fiber reinforced plastic 54) containing a glass cloth 52 is attached to the front surface and the back surface, and a copper foil 551 to be a wiring layer 55 is formed under the fiber reinforced plastic 54 on the back surface side. Then, the metal plate 51, the fiber reinforced plastic 54 and the copper foil 551 in this state are heat-pressed,
As shown in FIG. 7C, the insulating resin 53 of the fiber reinforced plastic 54 is poured into the terminal insertion hole 511. Next, as shown in FIG. 7D, copper foil 551 (FIG. 7B)
(See) to form a wiring layer 55 having a predetermined circuit pattern. Next, as shown in FIG. 7E, the central portion of the through hole 511 filled with the insulating resin 53 is re-pierced so that the insulating resin 53 remains on the inner wall of the previous terminal insertion hole 511. The terminal insertion hole 561 is formed.

In the metal core printed wiring board formed as described above, since the through hole 511 is filled with the insulating resin 53, the insulating resin 53 in the fiber reinforced plastic 54 must be increased, which increases the thermal resistance and heat dissipation. Equally impair sex. Correspondingly, when the amount of the insulating resin 53 is reduced, the inside of the hole cannot be completely filled and a cavity is formed, which causes a short circuit between the terminal and the metal plate 51. Further, when the central portion of the through hole 511 filled with the insulating resin 53 is re-drilled, the insulating resin 53
Cracks occur in the product, resulting in poor insulation. Moreover, since the resin is cured by hot pressing, the productivity is poor. Here, in response to the problem of increased thermal resistance, a method has been developed in which the cylindrical insulating resin 60 shown in the perspective view of FIG. 8 is inserted into the through hole. FIG. 9 is a process diagram showing a conventional metal core printed wiring board in which an insulating resin is inserted into the terminal insertion holes of lead components in the order of manufacturing steps.

As shown in FIG. 9A, a metal plate 61 is prepared. Next, as shown in FIG. 9B, the metal plate 6
Through holes 62, 62 are formed in 1. Next, in FIG. 9C, an insulating layer 64 is attached to the upper surface of the metal plate 61, and a copper foil 651 to be the wiring layer 65 is formed on the upper surface of the insulating layer 64. Then, as shown in FIG. 9D, the through holes 62, 6
2, the insulating resin 60, 60 shown in the perspective view of FIG. 8 is inserted, and as shown in FIG. 9E, the copper foil 651 (FIG. 9C) is inserted.
(See reference) is etched to form a wiring layer 65 forming a predetermined circuit pattern. Next, as shown in FIG. 9 (f), the central portion of the through hole 62 filled with the insulating resin 65 is re-drilled, and the insulating layer 64 and the wiring layer 65 are bored so as to communicate with the through hole 62, and insulation is performed. A new terminal insertion hole 66 is formed so that the resin 65 remains on the inner wall of the front through hole 62.

In such a printed wiring board, when there are a large number of through holes 62 into which the insulating resin 60 is inserted, the insulating resin 60 must be inserted individually, which is troublesome. Further, when the central portion of the through hole 62 filled with the insulating resin 60 is re-drilled, a crack is generated in the insulating resin 60, resulting in poor insulation.

[0009]

SUMMARY OF THE INVENTION In the conventional metal core printed wiring board device described above, in order to ensure the insulation of the terminal insertion hole with a small amount of fiber reinforced plastic, an insulating resin is inserted into the through hole to insert the terminal insertion hole. However, if a large number of terminal insertion holes are required, it is necessary to insert the insulating resin separately for each, which is time-consuming, and the center portion of the terminal insertion hole filled with the insulating resin must be re-drilled. When doing
In many cases, the insulating resin was cracked.

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal core printed wiring board device which eliminates the above problems and is capable of obtaining a reliable insulating property of a terminal insertion hole with a simple process and a small amount of insulating resin.

[0011]

According to the present invention, there is provided a metal core printed wiring board in which a metal plate is used as a core, a through hole for inserting a terminal of a lead component is formed in the metal plate, and an insulating layer is formed on an inner surface of the through hole. In the manufacturing method, after forming the through-hole in the metal plate, a molten thermoplastic insulating resin is attached to the tip of a rod-shaped member having a diameter smaller than that of the through-hole, and the tip of the rod-shaped member is passed through the terminal insertion hole. Then, the thermoplastic insulating resin is applied to the through holes.

[0012]

According to this structure, the molten thermoplastic insulating resin is attached to the tip of the rod-shaped member, and the tip of the rod-shaped member is passed through the through hole for inserting the terminal to penetrate the thermoplastic insulating resin. By forming the terminal insertion hole by coating the hole, it is possible to obtain reliable insulation of the terminal insertion hole with a simple process and a small amount of insulating resin.

[0013]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. 1 to 3 are process diagrams showing an embodiment of a method of manufacturing a metal core printed wiring board according to the present invention in the order of manufacturing steps.

In this embodiment, first, as shown in FIG. 1A, a metal plate 11 is prepared. The metal plate 11 has a thickness of approximately 1 to
Made of 3mm aluminum. Next, as shown in FIG. 1B, through holes 1 for inserting terminals are formed in the metal plate 11.
11 is formed. Next, as shown in FIG. 1 (c), a metal rod 121 having a diameter smaller than that of the through hole 111 is provided on the metal plate 122 so as to project downward, and the insulating resin coating metal fitting 123 is attached to the metal plate 1.
1, the tank 13 filled with the molten thermoplastic insulating resin 131 is arranged below the metal plate 11, the insulating resin coating fitting 123 is lowered, and the metal rod 121 is inserted into the through hole 111. To insert. After this, as shown in FIG.
Further, the insulating resin coating metal fitting 123 is lowered to make the metal rod 1
The tip of 21 is submerged in the thermoplastic insulating resin 131. Next, as shown in FIG. 2 (e), the insulating resin application fitting 12 in which the thermoplastic insulating resin 131 is attached to the tip of the metal rod 121
3 is moved up and the tip of the metal rod 121 to which the thermoplastic insulating resin 131 is attached is passed through the through hole 111, so that the thermoplastic insulating resin 131 is applied to the inner surface of the through hole 111 as shown in FIG. Apply. These FIG. 1 (c)-
By repeating the operation of FIG.
The thermoplastic insulating resin 131 is surely applied to the inner surface of 1. The thermoplastic insulating resin 131 applied to the inner surface of the through hole 111 absorbs heat into the atmosphere and the metal plate 11 and solidifies.

The metal plate 11 having the thermoplastic insulating resin 131 applied to the inner surface of the through hole 111 in this manner is shown in FIG.
In (g), the insulating layers 141 and 142 are attached to the upper and lower surfaces, and the copper foil 1 becomes the wiring layer 15 on the upper surface of the upper insulating layer 14.
51 is formed. Next, as shown in FIG. 3 (h), the copper foil 151 (see FIG. 3 (g)) is etched to form the wiring layer 15 forming a predetermined circuit pattern. After this,
As shown in (i), the insulating layers 141 and 142 and the wiring layer 1
5 is provided at a position corresponding to the center of the through hole 111,
A new terminal insertion hole 161 is formed with the thermoplastic insulating resin 131 applied to the inner surface of the through hole 111. The metal core printed wiring board is manufactured as described above.

According to this embodiment, the terminal insulating hole 161 can be easily insulated by applying the thermoplastic insulating resin 131 to the through hole 111 at the tip of the metal rod 121. Further, the thermoplastic insulating resin 131 applied to the terminal insertion holes 161 does not need to be thermoset, and the insulating layer can be formed only by cooling, so that the productivity is high. Further, the thermoplastic insulating resin 131 on the inner wall of the terminal insertion hole 34 is changed by changing the clearance between the through hole 111 and the metal rod 121.
The thickness of the insulating layer can be adjusted by. When a plurality of through-holes 111 are formed in the metal plate 11, a plurality of metal rods 121 corresponding to the plurality of through-holes 111 in the insulating resin coating fitting 123 are provided on the metal plate 122 so as to project a plurality of through-holes. Since the thermoplastic insulating resin 131 can be applied simultaneously to the holes 111, the manufacturing cost can be reduced. FIG. 4 shows another embodiment according to the present invention. Another embodiment of FIG. 4 is
This further ensures the insulation of the terminal insertion hole.

First, as shown in FIG. 4A, a metal plate 21 having insulation layers 22 and 22 attached to the front and back surfaces thereof is prepared. As shown in FIG. 4B, a through hole 23 is formed at the center of the portion of the metal plate 21 on which the insulating layer 22 is attached. Next, as shown in FIG. 4C, using the insulating resin coating fitting shown in FIG. 1 and the tank filled with the thermoplastic insulating resin, the thermoplastic insulating resin 131 is coated on the inner surface of the through hole 23. ..
Then, a wiring pattern (not shown) is formed to obtain a metal core printed wiring board. According to this embodiment, the insulating layer 22,
Since the thermoplastic insulating resin 131 can be directly applied to 22,
The insulation is improved. FIG. 5 shows another embodiment according to the present invention, which further secures the insulation of the terminal insertion hole.

First, as shown in FIG. 5A, the insulating layer 3
2 and the metal plate 31 on which the copper foil 33 is formed are prepared. Next, as shown in FIG. 5B, the metal plate 31, the insulating layer 32
And the copper foil 33 is communicated with each other to form a through hole 34. Next, using the insulating resin coating metal fitting shown in FIG. 1 and the tank filled with the thermoplastic insulating resin, as shown in FIG.
The thermoplastic insulating resin 131 is applied to the inner surface of the through hole 34. Next, the thermoplastic insulating resin 131 squeezed out from the through hole 34 is ground with a polishing device (a grinder or the like). After that, the copper foil 33 is etched to form a wiring pattern,
Use a metal core printed wiring board. According to this embodiment, since the thermoplastic insulating resin 131 can be directly applied to the through holes 34 of the copper foil 33, the insulating property is further improved as compared with the embodiment of FIG.

In the embodiment shown in FIGS. 1 to 5, the metal rod 121 is used as the member for applying the thermoplastic insulating resin 131 to the through hole, but other rod-shaped members such as FRP rod and ceramic rod are used. You may use another thing. Further, in the embodiment of FIG. 5, if the terminals are not directly connected to the wiring layer 33, the thermoplastic insulating resin 131 protruding from the through holes 34 does not have to be scraped by a polishing device.

[0020]

As described above, according to the present invention,
By applying the thermoplastic insulating resin melted by the metal rod to the through hole for inserting the terminal, it is possible to easily insulate the terminal inserting hole. Further, the thermoplastic insulating resin applied to the through holes does not need to be thermoset, and the insulating layer can be formed only by cooling, thus improving the productivity.

[Brief description of drawings]

FIG. 1 is a process drawing showing an embodiment of a method of manufacturing a metal core printed wiring board according to the present invention until a thermoplastic insulating resin is attached to the tip of a metal rod.

FIG. 2 is a process drawing of a process of applying a thermoplastic insulating resin adhesion to a through hole in the method for manufacturing the metal core printed wiring board of FIG.

FIG. 3 is a process drawing of a process of forming a terminal insertion hole in the method of manufacturing the metal core printed wiring board of FIG.

FIG. 4 is a process drawing showing another embodiment of the method for manufacturing a metal core printed wiring board according to the present invention.

FIG. 5 is a process drawing showing another embodiment of the method for manufacturing a metal core printed wiring board according to the present invention.

FIG. 6 is a cross-sectional view showing a conventional metal core printed wiring board.

FIG. 7 is a process drawing showing a manufacturing process of a conventional metal core printed wiring board provided with terminal insertion holes for lead components.

FIG. 8 is a perspective view showing an insulating resin used in a conventional metal core printed wiring board.

FIG. 9 is a process drawing showing a manufacturing process of a conventional metal core printed wiring board using the insulating resin of FIG.

[Explanation of symbols]

 11 Metal Plate 111 Through Hole 121 Metal Rod 131 Thermoplastic Insulating Resin

Claims (1)

[Claims] 1. A method for manufacturing a metal core printed wiring board, comprising using a metal plate as a core, forming a through hole for inserting a terminal of a lead component in the metal plate, and forming an insulating layer on an inner surface of the through hole. After forming the through-hole, the molten thermoplastic insulating resin is attached to the tip of the rod-shaped member having a smaller diameter than the through-hole, and the tip of the rod-shaped member is passed through the terminal insertion hole to remove the thermoplastic insulating resin. A method for manufacturing a metal core printed wiring board, characterized in that the through hole is applied.