JP2608122B2 - Printed wiring board - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board having a thick conductor circuit through which a large current can flow.

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

For this reason, when a large current needs to flow through a power module or the like, the circuit layer needs to be thicker than a normal one. However, as shown in FIG. 2, after attaching a thick metal layer 103 to a base plate 101 via an insulating layer 102 (FIG. A), a predetermined portion is protected by an etching resist 107 and the circuit is etched by etching. Try to form a metal layer 10
Since the thickness of 3 is too long, the etching becomes extremely long, and during that time, the etching of the circuit side not protected by the etching resist (so-called side etching) proceeds as shown in FIG. Can only be formed.

Therefore, conventionally, when it is necessary to form a thick circuit, a method as shown in FIG. 3 has been used. That is, first, as shown in FIG. A, a copper foil 205 having a normal thickness is stuck on a base plate 201 (a metal plate such as aluminum is preferably used in terms of heat dissipation) via an insulating layer 202, and The copper foil circuit 20 is etched as shown in FIG.
Form 5a. Thereafter, in a separate step, the circuit member 203 formed into a predetermined shape by, for example, press-punching a copper plate is soldered (solder 206) to a predetermined portion of the copper foil circuit 205a, thereby forming a wall as shown in FIG. Form a thick circuit.

[Problems to be Solved by the Invention] However, in the above-described conventional technology, the soldering process of the circuit member is extremely complicated, the productivity is extremely low, and the position shift occurs during the soldering, so that the precision is low. There is a problem that alignment is difficult.

Further, in order to prevent the circuit member from moving due to heat when mounting the electronic component, high-temperature solder having a high melting point must be used for soldering the circuit member, which is not easy to handle.

Furthermore, the solder interposed between the copper foil circuit and the circuit member becomes a thermal resistance, and even if a metal plate having excellent heat dissipation is used as the base plate, the heat generated by the circuit member is not quickly transmitted to the metal plate. is there.

The present invention has been made in view of such a point,
An object of the present invention is to provide a printed wiring board having a thick circuit through which a large current can flow, and which is easy to manufacture and has high positional accuracy of the circuit.

[Means for Solving the Problems] In the present invention, a conductor circuit member formed in a desired shape is fitted to an insulating plate having a hole corresponding to the conductor circuit member and formed at a predetermined position. The above object is achieved by providing the circuit layer formed on at least one surface of the base plate via an insulating layer.

[Operation] In the present invention, a circuit layer is formed by attaching an insulating plate in which a thick circuit member manufactured by punching or the like in a separate process is fitted to a predetermined position to a base plate to form a circuit layer. There is no need to solder one by one, and the positioning accuracy of the circuit is much improved.

Here, as a method of positioning the circuit member, it is conceivable to use a concave shape in which the circuit member is fitted, and then remove the concave shape later.However, in this method, the concave shape is required unless some clearance is provided between the concave shape and the circuit member. There is a problem in that the circuit member cannot be removed properly and an excessive stress is applied to the circuit member. In order to solve this problem, for example, it is conceivable to use a concave mold that is excellent in mold release properties made of fluorine and is softer than the circuit member, or that the concave mold is pulled out using a special machine. And it is not a good idea.

In this regard, in the present invention, since the circuit member is attached to the base plate while the circuit member is fitted, the insulating plate is used as a positioning concave shape,
The step of removing the mold is unnecessary, and there is no need to provide a clearance between the circuit member and the fitting hole, so that the circuit member can be positioned with higher accuracy.

In general, when a thick circuit is formed, a step on the surface becomes large and it becomes difficult to apply a solder resist or the like. However, in the present invention, since the circuit member is fitted to the insulating plate, There are few steps, it is easy to apply a solder resist or the like in a later step, and it is excellent in insulation between circuits.

The insulating plate in the present invention is not particularly limited as long as a predetermined insulating property is ensured, and various other types such as a glass epoxy plate can be used. In this case, it is preferable to use an insulating plate having a high thermal conductivity such as an epoxy plate containing alumina fibers. Further, the thickness of the insulating plate is preferably equal to or smaller than the circuit member because a sufficient pressure is applied to the circuit member when the circuit layer is attached by a vacuum press or the like.

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

Further, the materials constituting the circuit member include copper, aluminum, nickel-plated copper, aluminum
A copper-clad plate, a copper-plated aluminum plate, or the like can be used, and various conductor materials can be selected according to the circuit to be constituted.

As the insulating layer interposed between the circuit layer and the base plate, various adhesive insulating materials such as glass epoxy prepreg, epoxy prepreg containing alumina fiber, epoxy resin or polyimide resin filled with alumina or quartz powder can be used. If a metal plate is used as the base plate and a particularly high insulating property is required, an insulating layer having a predetermined thickness is formed on the base plate, the resin is cured, and then an insulating adhesive is applied. A circuit member may be attached to the circuit member.

Example Example 1 FIGS. 1a and 1b are cross-sectional views schematically showing steps of manufacturing a printed wiring board according to an example of the present invention.

A glass epoxy plate and a copper plate having a size of 250 mm × 250 mm and a thickness of 1.5 mm were subjected to press punching to produce a circuit member 3 having a predetermined shape and an insulating plate 4 having holes at predetermined positions corresponding to the circuit member 3. . Then, the circuit member 3 and the insulating plate 4 are fitted to each other to form a circuit layer 10, which is vacuum-pressed onto a base plate 1 made of a 1.5 mm-thick glass epoxy plate via a glass epoxy prepreg as shown in FIG. To obtain a printed wiring board as shown in FIG.

Example: 2 In the same manner as in Example 1, press-punching is performed on a 250 mm × 250 mm, 1.5 mm thick epoxy board containing alumina fiber and a copper board to correspond to a circuit member having a predetermined shape and a circuit member at a predetermined position. An insulating plate having holes having the following shapes was manufactured. And
The circuit member and the insulating plate are fitted together to form a circuit layer, which is then vacuum-pressed onto a 1.5 mm-thick nickel-plated copper plate through an epoxy prepreg containing alumina fiber (trade name: Max Paper). Thermocompression bonding
A printed wiring board for a power circuit was obtained.

In each of the above embodiments, the circuit member and the insulating plate were previously fitted and then thermocompression-bonded to the base plate by a vacuum press. However, in some cases, the insulating plate was first attached to the base plate, and then The circuit member may be fitted and adhered to the board.

[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 conductor circuit member and the insulating plate and attaching them to the base plate. It is very easy to manufacture and the position accuracy of the circuit is greatly improved.

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

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

The printed wiring board having the excellent effects as described above is extremely useful when a large current needs to flow in a power module or the like.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing process of a printed wiring board according to an embodiment of the present invention, and FIGS. 2 and 3 are sectional views for explaining a conventional example. [Description of Signs of Main Parts] 1... Base plate 2... Insulating layer 3... Circuit member 4... Insulating plate 10.

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shinichi Konishi 5-1-9 Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Furukawa Electric Industry Co., Ltd. Hiratsuka Works (56) References JP-A-1-266790 (JP, A) JP 62-189790 (JP, A)

Claims (1)

(57) [Claims] 1. A conductor circuit member formed in a desired shape,
A circuit layer formed by fitting a hole having a shape corresponding to the conductive circuit member into an insulating plate formed at a predetermined position is provided on at least one surface of the base plate via the insulating layer. Parint wiring board.