JPH066010A - Manufacture of microwave transmission circuit substrate - Google Patents

Abstract

PURPOSE:To obtain a microwave, transmission circuit substrate at low cost by a relatively simple process. CONSTITUTION:A tabular thermoplastic resin substrate, on which a circuit pattern is formed at least on one direction, is placed on the first mold 13, the second mold 14 is brought closer to the first mold 13, evacuated from a sucking hole 13b under heating, compressed air is introduced from a compressed air feeding hole 14b, the substrate is processed in such a manner that it is formed in line with the inner surface of the recessed part 13a, and a microwave transmission circuit is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional circuit board used as a wiring board or the like, and more particularly to a method for obtaining a three-dimensional circuit board having a desired shape by processing a board on which a circuit pattern is previously formed.

[0002]

2. Description of the Related Art FIG. 5 is a perspective view showing an example of a conventional three-dimensional circuit board. In the three-dimensional circuit board 1, a recess 2a is formed in the center of a board 2 made of an insulating material such as synthetic resin. As shown in the drawing, conductive portions 3a to 3d forming a circuit pattern are formed on both surfaces of the substrate 2, and the conductive portions 3a to 3d are formed so as to extend into the recess 2a. By the way, when manufacturing the three-dimensional circuit board 1,
Conventionally, a molding method called a one-shot molding method or a two-shot molding method has been adopted.

In the one-shot molding method, a substrate having a three-dimensional shape is molded by injection molding, and electroless copper plating is performed on the entire surface by etching treatment and catalyst treatment. In this case, the semi-additive method of masking the parts other than the circuit part with a resist, electroplating the circuit part, and peeling the resist, and the mold with the transfer sheet of the synthetic resin molding material forming the substrate 2 previously inserted There is a transfer molding method in which the conductive portions 3a to 3d are injected into the inside, heated and pressed to have a three-dimensional shape, and the conductive portions 3a to 3d are transferred to one surface of the substrate 2.

In the two-shot molding method, the three-dimensional circuit board 1 on which the conductive portions 3a to 3d are formed is obtained by performing the molding process in two stages. That is, first, a primary molded product is obtained using the primary molding material. In this primary molded product, the portions where the conductive portions 3a to 3d are finally formed are projected from the surface more than the remaining portions. After that, the surface of the primary molded product is treated with an acid catalyst after etching so that it can be plated. Next, the primary molded product is placed in a secondary mold, and the secondary molding material is molded around the portions where the conductive portions 3a to 3d are finally formed, and the portions where the conductive portions 3a to 3d are formed are formed. The remaining part should be coplanar. Finally, in the secondary molded product obtained as described above, the portions where the conductive portions 3a to 3d are formed are plated to form the conductive portions 3a to 3d.

[0005]

As described above, in the method for manufacturing a three-dimensional circuit board using the one-shot molding method, a mold having a complicated shape corresponding to the shape of the finally obtained three-dimensional circuit board 1 is obtained. Had to be molded using. Therefore, there is a problem that the manufacturing cost of the mold is very high. Further, there is a problem that a transfer sheet for forming the conductive parts 3a to 3d is required, and the cost is further increased by that amount. On the other hand, in the two-shot molding method, it is necessary to perform the molding step twice, and for this reason, two types of molds are required. Not only that, but also for the plating treatment, surface treatment such as etching or acid catalyst had to be performed. Therefore, the cost is very high even in the manufacturing method using the two-shot molding method.

An object of the present invention is to provide a method for manufacturing a three-dimensional circuit board at a low cost by a relatively simple process.

[0007]

According to the present invention, a flat plate-shaped substrate having a circuit pattern formed on at least one surface thereof and made of a thermoplastic resin is prepared, and a first mold having a recess and a first mold are provided. When the substrate is sandwiched between the first mold and the second mold, the inside of the recess of the first mold is vacuum-sucked from the first mold side, and / or the second mold side. The method for manufacturing a three-dimensional circuit board is characterized in that the substrate is processed along the recess by introducing a compressed gas into the recess.

[0008]

In the method of manufacturing a three-dimensional circuit board according to the present invention, the three-dimensional circuit board is obtained by processing a flat board having a circuit pattern formed in advance. Therefore, since it is easy to form a circuit pattern on a flat plate-shaped substrate, the circuit pattern-formed substrate can be prepared by a very simple process. Further, when processing the substrate, the substrate is processed along the recess by vacuum suction or introduction of compressed gas under heating, so the processing process is relatively simple using one type of mold. In addition, the processing can be performed while preventing contact between the die and the circuit pattern on the substrate.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be clarified by describing embodiments of the present invention with reference to the drawings. First, as shown in FIG. 2, a flat substrate 11 is prepared.
The substrate 11 has a rectangular flat plate shape, and its one surface 11
Conductive portions 12a to 12d forming a circuit pattern are formed on a. As a material forming the substrate 11, any material can be used as long as it is a thermoplastic resin. Further, the conductive portions 12a to 12d have the following first to fourth portions.
Can be formed by various methods such as the above method.

In the first method, after the substrate 11 is molded using a material mixed with a plating catalyst such as palladium, the conductive portions 12a to 12d are masked except the portions where the conductive portions 12a to 12d are formed. After the etching process is performed on the portion where the metal is to be formed, a conductive material such as Cu is plated to form the conductive portions 12a to 12d. In the second method, the substrate 11 in which the plating catalyst is not mixed is molded, and the upper surface of the substrate is masked except the portions where the conductive portions 12a to 12d are formed, and the portions where the conductive portions 12a to 12d are formed. Is etched and treated with a catalyst, and then a conductive material is plated to form conductive portions 12a to 12d.

In the third method, a foil made of a conductive material such as Cu is attached to the entire surface of one side of the substrate 11 and, thereafter, only the portions where the conductive portions 12a to 12d are to be formed are masked and left. Regions are removed by etching. In the fourth method, a conductive paste is printed on one surface of the substrate 11 and solidified or baked to form the conductive portion 1.
2a to 12d are formed. The first to fourth methods described above are the substrate 1 in which the conductive portions 12a to 12d are formed on one surface.
1 is merely an example of the method of preparing 1, and the conductive portions 12a to 12d can be formed by any other method.

Next, as shown in FIG. 1, the first die 13
Then, a forming die including the second die 14 is prepared, and the substrate 11 is placed on the first die 13. The first mold 13 has a recess 13a at the center. In addition, the concave portion 13a is formed so that the inside of the concave portion 13a can be vacuumed as indicated by an arrow A in the drawing.
A suction hole 13b is formed facing the. Suction hole 13b
Is connected to a vacuum suction device (not shown). On the other hand,
The second mold 14 has a protrusion 14 that enters the recess 13a.
A compressed air supply hole 14b is formed in the center of the protruding portion 14a for supplying compressed air.
The compressed air supply hole 14b is connected to a compressed air supply device such as a compressor (not shown).

At the time of molding, the first and second molds 13,
14 is heated to a temperature equal to or higher than the temperature at which the thermoplastic resin forming the substrate 11 is softened, and the second mold 14 is heated in that state.
Is lowered to the first mold 13 side. Then, compressed air is blown from the compressed air supply hole 14b toward the substrate 11 side, and vacuum suction is performed from the suction hole 13b, so that the substrate 11 is processed along the inner surface of the recess 13a as shown in FIG. 1B. To do. In this case, by adopting only one of the introduction of compressed air and vacuum suction, the substrate 1
1 may be processed along the inner surface of the recess 13a.

The degree of compressed air and vacuum suction cannot be uniquely determined because it depends on the material and thickness of the substrate 11 used and the shape (depth and area) of the recess 13a. For example, when a substrate made of PPS and having a thickness of 0.3 mm is used, and the depth and bottom area of the recess 13a are 5 mm and 3 mm ² , respectively,
The heating temperature is 260 ° C., and usually the vacuum suction is 0.2
In kg / cm ² or so, the introduction of compressed air 10 kg / cm
^{You only have to do} about ² .

The three-dimensional circuit board obtained as described above is shown in FIG. As is clear from FIG. 3, in the obtained three-dimensional circuit board 15, the recess 11b is formed in the center of the substrate 11, and the conductive portions 12a to 12d are formed in the recess 11b. In the method for manufacturing a three-dimensional circuit board according to the present embodiment, the conductive portions 12a to 12d are formed in advance on the board 11 made of the flat plate-shaped thermoplastic resin as described above, and the board 11 is heated under heating as described above. The recess 11b is formed by using compression and vacuum suction along the recess 13a of the mold. Therefore, as is clear from FIGS. 1A and 1B, it is not necessary to bring all of the upper surface of the substrate 11 on which the conductive portions 12a to 12d are formed into contact with the upper mold 14, and therefore, at the time of molding. The conductive portions 12a to 12d are unlikely to be damaged or broken.

Although compressed air is used as the compressed gas in the above embodiment, a gas other than air, such as nitrogen gas, may be used. Further, as shown in the cross-sectional view in FIG. 4, as the first mold 23, one having an undercut groove 23c formed in the side wall portion of the recess 23a may be used, whereby the undercut recess 23a is formed.
It is possible to easily obtain a three-dimensional circuit board on which is formed.
As described above, by using the manufacturing method of the present invention, a three-dimensional circuit board having a recess having a complicated shape can be manufactured by an extremely simple process. Further, the substrate used in the present invention may be a sheet-like one such as a flexible substrate.

[0017]

According to the present invention, since the circuit pattern is preliminarily formed on the flat plate-shaped substrate, it is necessary to carry out a complicated catalyst activation treatment for forming the circuit pattern and a plurality of molding steps. Absent. Moreover, it is only necessary that the inner surface of the first mold is formed so as to be able to follow the recess, and the second mold which is the other mold is prepared with a very high accuracy. No need. Therefore, the three-dimensional circuit board can be manufactured inexpensively and efficiently.

Moreover, since the substrate is processed under heating by vacuum suction and / or introduction of compressed gas, the circuit pattern does not come into strong contact with the second mold during processing. Therefore, there is no risk of the surface of the circuit pattern being damaged or breaking during processing.

[Brief description of drawings]

1A and 1B are cross-sectional views showing a process of processing a flat plate-shaped substrate along a concave portion of a first mold in one embodiment of the present invention.

FIG. 2 is a perspective view showing a flat plate-shaped substrate prepared in an example.

FIG. 3 is a perspective view showing a three-dimensional circuit board obtained according to an example.

FIG. 4 is a sectional view for explaining another example of the shape of the mold used in the present invention.

FIG. 5 is a perspective view showing a three-dimensional circuit board obtained by a conventional manufacturing method.

[Simple explanation of symbols]

 11 ... Substrate 13 ... First mold 14 ... Second mold 13b ... Suction hole 14b ... Compressed air supply hole

Claims (1)

[Claims] 1. A flat plate-shaped substrate having a circuit pattern formed on at least one surface and made of a thermoplastic resin is prepared, and is provided between a first mold having a recess and a second mold. When the substrate is sandwiched and heat-molded, the gas compressed in the recess of the first mold by vacuum suction from the first mold side and / or from the second mold side into the recess The method of manufacturing a three-dimensional circuit board according to claim 1, wherein the board is processed so as to be along the recess.