JPH02137392A - Printed wiring board - Google Patents

Abstract

PURPOSE:To easily manufacture the title board and to sharply enhance a positional accuracy of a circuit by a method wherein a conductor circuit member and an insulating sheet are fit, they are pasted on a base sheet and a circuit layer is formed. CONSTITUTION:A glass epoxy sheet and a copper sheet are stamped; a circuit member 3 of a prescribed shape and an insulating sheet 4 having a hole, in a prescribed position, of a shape corresponding to the circuit member 3 are manufactured. The circuit member 3 and the insulating sheet 4 are fit; a circuit layer 10 is formed; this is pressure-bonded thermally, by using a vacuum press, to a base sheet 1 composed of a glass epoxy sheet via a glass epoxy prepreg; a printed wiring board is obtained. Thereby, it is possible to obtain the printed wiring board which can be manufactured easily and whose positional accuracy of a circuit is high.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printed wiring board on which a thick conductor circuit through which a large current can flow is formed.

[Prior art] In a normal printed wiring board, the thickness is 18 μm or 35 μm.
Since the circuit is formed from copper foil as thick as an intestine, there is a limit to the allowable current even if a metal plate with excellent heat dissipation properties is used as the base plate.

For this reason, in cases where a large current needs to flow, such as in a power module, the circuit layer needs to be thicker than usual. However, as shown in FIG. 2, after a thick metal layer 103 is attached to a base plate 101 via an insulating layer 102 (FIG. When trying to form a circuit, the metal layer 103 is thick and the etching process becomes very long.
During this time, as shown in the figure, etching progresses on the side of the circuit that is not protected by the etching resist (so-called side etching), so in practice it is only possible to form a circuit with a thickness of about 150 μm.

Therefore, conventionally, when it is necessary to form a particularly thick circuit, a method as shown in FIG. 3 has been used. That is, as shown in FIG. By etching, a copper foil circuit 205a is formed as shown in the figure. Thereafter, in a separate process, for example, a circuit member 203 formed into a predetermined shape by press punching a copper plate is soldered (solder 206) to a predetermined location of the copper foil circuit 205a.
Form a thick circuit like this.

[Problems to be Solved by the Invention] However, in the conventional technology as described above, soldering of circuit members is an extremely complicated process, productivity is extremely low, and soldering sometimes causes misalignment. There is a problem that precise alignment is difficult.

In addition, the heat generated when mounting electronic components may damage the circuit components.
In order to prevent the circuit members from moving, high-temperature solder with a high melting point must be used to solder the circuit members, which is not easy to handle.

Furthermore, the solder interposed between the copper foil circuit and the circuit components becomes a thermal resistance, and even if a metal plate with excellent heat dissipation properties is used as the base plate, the heat generated in the circuit components is not quickly transferred to the metal plate. be.

The present invention has been made in view of the above points, and is a printed wiring board having a thick circuit that can flow a large current, which is easy to manufacture and has high circuit positioning accuracy. The purpose is to provide boards.

[Means for Solving the Problems] In the present invention, a conductive circuit member formed in a desired shape is fitted into an insulating plate in which a hole of a shape corresponding to the conductive circuit member is bored at a predetermined position. The above-mentioned problem is achieved by providing a circuit layer consisting of the following on at least one surface of the base plate with an insulating layer interposed therebetween.

[Function] In the present invention, the circuit layer is formed by pasting on the base plate an insulating plate in which a thick circuit member manufactured by punching or the like in a separate process is fitted in a predetermined position. There is no need to solder each piece one by one, and the positioning accuracy of the circuit is much improved compared to the conventional method.

Here, as a method for positioning the circuit component, it is possible to use a concave mold into which the circuit component is fitted and then remove the concave mold later. However, with this method, the concave mold cannot be moved unless a certain amount of clearance is provided between the concave mold and the circuit component. There is a problem in that the circuit member cannot be removed properly and excessive stress is applied to the circuit member. To solve this problem, for example, it is possible to use a concave mold made of fluorine resin that has excellent mold releasability and is softer than the circuit material, or to use a special machine to pull out the concave mold, but both methods are expensive to manufacture. It cannot be said that it is a good idea as it becomes expensive.

In this regard, in the present invention, an insulating plate is used as a recessed mold for positioning, and the circuit member is attached to the base plate while being fitted, so there is no need to remove the mold, and there is no clearance between the circuit member and the fitting hole. There is no need to take ≦, and circuit members can be positioned with higher precision.

Additionally, when a thick circuit is formed, the surface level difference becomes large, making it difficult to apply solder resist, etc.
In the present invention, since the circuit member is fitted into the insulating plate, there are few steps on the surface, and it is easy to apply a solder resist or the like in a subsequent process, and the insulation between the circuits is also excellent.

The insulating board in the present invention is not particularly limited as long as a predetermined insulating property is ensured, and various other materials such as a glass epoxy board can be used, but the heat dissipation of the printed wiring board is particularly important. In this case, it is preferable to use an insulating board with high thermal conductivity such as an epoxy board containing alumina fiber. Further, it is preferable that the thickness of the insulating plate be equal to or somewhat thinner than the circuit member, since sufficient pressure can be applied to the circuit member when the circuit layer is attached by vacuum pressing or the like.

On the other hand, the base plate in the present invention is not particularly limited in terms of thickness or material, but from the viewpoint of heat dissipation, it is desirable to use a metal plate such as aluminum, copper, or copper plated with nickel.

Copper is also used as a material for making circuit members.

Aluminum, copper plated with nickel, aluminum-copper clad plate, aluminum plated with copper, etc. can be used, and various conductor materials can be selected depending on the circuit to be constructed.

In addition, various adhesive insulating materials such as glass epoxy prepreg, alumina fiber-filled epoxy prepreg, epoxy resin filled with alumina or quartz powder, or polyimide resin can be used as the insulating layer interposed between the circuit layer and the base board. . If a particularly high level of insulation is required when using a metal plate for the base plate, first form an insulating layer of a predetermined thickness on the base plate, cure the resin, and then apply an insulating adhesive. A method can be adopted in which the circuit member is pasted through the substrate.

[Example] Example: l Figures 1a and 1b are cross-sectional views schematically showing the manufacturing process of a printed wiring board according to an example of the present invention.

A glass epoxy plate and a copper plate of 250 mm x 250 mm and a thickness of 1.5 mm were subjected to press punching to produce a circuit member 3 in a predetermined shape and an insulating plate 4 having holes in a shape corresponding to the circuit member 3 at predetermined positions. . Then, this circuit member 3 and the insulating plate 4 are fitted to form a circuit layer IO, which is then layered with a thickness of 1.5
A printed wiring board as shown in the figure was obtained by thermocompression bonding on a base plate 1 made of a glass epoxy plate with a thickness of mm using a vacuum press.

Example: 2 Same as Example 1, 250m+++X 250m
An insulating board having a circuit member of a predetermined shape and a hole of a shape corresponding to the circuit member at a predetermined position was produced by performing press punching on an alumina fiber-containing epoxy board and a copper plate with a thickness of 1.5 mm. Then, this circuit member and the insulating board were fitted to form a circuit layer, and this was layered for 1.5 seconds via an epoxy prepreg containing alumina fiber (product name: Max Vapor).
A printed wiring board for a power circuit was obtained by thermocompression bonding using a vacuum press onto a base plate made of a nickel-plated copper plate having a thickness of 0.4 mm.

In each of the above examples, the circuit member and the insulating plate were fitted in advance and then thermocompressed to the base plate using a vacuum press. However, in some cases, the insulating plate was attached to the base plate first, and then The circuit member may be fitted into the insulating plate and bonded.

[Effects of the Invention] As described above, in the printed wiring board according to the present invention, the circuit layer is formed by fitting the conductive circuit member and the insulating plate and pasting them on the base board, so that the printed wiring board according to the present invention is more efficient than the conventional one. It is very easy to manufacture, and the positioning accuracy of the circuit is greatly improved.

Furthermore, since there are few steps in the circuit layer, it is easy to apply solder resist or the like to the surface, and the insulation between circuits is also excellent.

Furthermore, since no solder or the like is present in the circuit, heat transfer is not hindered.

A printed wiring board having the above-mentioned excellent effects is extremely useful in cases where a large current needs to flow, such as in a power module.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the manufacturing process of a printed wiring board according to an embodiment of the present invention, and FIGS. 2 and 3 are sectional views illustrating a conventional example. [Explanation of symbols of main parts] 1...Base board 2...Insulating layer 3...Circuit member 4...Insulating board 10...Circuit layer

Claims (1)

[Claims] A circuit layer formed by fitting a conductive circuit member formed into a desired shape into an insulating plate in which a hole of a shape corresponding to the conductive circuit member is bored at a predetermined position is attached to a base plate through an insulating layer. A printed wiring board characterized in that the printed wiring board is provided on at least one surface of.