JPH0770794B2 - Electric circuit board manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electric circuit board on which an electric circuit can be easily provided.

[Conventional technology and problems]

Conventionally, various polymer materials have been used for substrates such as printed wiring boards, power transformer boards, and thyristor module boards.
From the viewpoint of rigidity and the like, thermosetting resins have been used as resins such as phenol resin laminates and glass-epoxy laminates. Therefore, the shape of such a substrate is limited to a flat plate. Recently, flexible substrates have been developed, but there is great demand for rigid and three-dimensional substrates.

However, it is very difficult and practically impossible to provide the electric wiring on the three-dimensional substrate by the conventional method.
Therefore, a method based on the two-color injection molding method has been proposed. However, when a substrate is made by this method, it is necessary to use a material that can be injection-molded, that is, a thermoplastic resin, but in that case, the heat resistance of the solder when attaching the component to the resulting substrate is insufficient. Therefore, in addition to the deformation of the substrate, since the thermal expansion coefficient is generally large, the substrate is deformed due to the difference in thermal expansion with the metal (generally copper) that forms the circuit when immersed in or in contact with the solder bath. Alternatively, there is a drawback that peeling occurs a number of times.

[Means for solving problems]

As a result of extensive studies to solve the above problems, the present invention shows that thermotropic liquid crystalline polyester (hereinafter simply referred to as “liquid crystalline polyester”) which exhibits anisotropy when melted is a thermoplastic resin and can be used for a substrate. It has excellent physical properties such as rigidity and thermal deformation resistance, and its thermal expansion is similar to that of metals, so it was found that circuit peeling does not occur even with rapid temperature changes such as immersion in a solder bath. The present invention has been completed.

That is, the present invention comprises: (a) a preformed mold formed of a thermotropic liquid crystalline polyester resin material that exhibits anisotropy when melted with easy plating, and (b) anisotropy when melted with difficult plating. And a predetermined mold formed of the thermotropic liquid crystalline polyester resin material showing the above, (a) and (b) above are on the surface of the molded article, and (a) is a pattern of an electric circuit. To form a board, and integrally injection-mold the substrate by two-color injection molding.
The present invention relates to a method for manufacturing an electric circuit board, which is characterized in that the pattern of the electric circuit is directly plated with metal.

The examples of the present invention shown in FIGS. 1 and 2 will be described.

A plan view of the electric circuit board is shown in FIG. 1. In the figure, the circuit portion 2 of the electric circuit board 1 is the surface of one predetermined mold made of the easily-platable liquid crystalline polyester resin material. It is an exposed part. The remaining non-circuit portion 3 is (b) a surface-exposed portion of one predetermined mold made of a liquid crystal polyester resin material having poor plating property. An electric circuit (not shown in FIG. 1) is formed on the circuit portion by plating.

The substrate of the present invention is made by a so-called two-color injection molding method in which an easily-platable thermoplastic resin material and a hard-to-plate thermoplastic resin material are integrally injection-molded. As a concrete embodiment in this case, (1) one predetermined mold corresponding to a portion where a circuit needs to be set is formed of an easily plateable liquid crystalline polyester resin material, and then, Is set in the cavity of a mold having a cavity in which the entire substrate is formed, and the space is filled with (B) a liquid crystal polyester resin material that is difficult to plate and is molded. This is a method in which a circuit forming portion and a non-circuit portion are integrally combined and injection molded so as to form a pattern of an electric circuit. When it is difficult to mold only the fine portion corresponding to the circuit portion, as shown in FIG. 2, the portion 5 forming the circuit on the substrate surface in (a) needs to be fine, but It is advisable to connect the inside so as to form the connecting portion 6 by being connected.

When there is a possibility that the flow of the non-plating liquid crystalline polyester resin material may be obstructed when the non-circuit part mold (b) is injection-molded, for example, as shown in FIGS. As described above, it is preferable to form the holes 4 in the mold (a).

(2) Contrary to (1), the type of non-circuit part referred to in (1) (b)
Is first molded with a difficult-to-plate liquid crystalline polyester resin material, then placed in another mold for circuit part molding,
This is a method of injection molding so as to fill the space with a liquid crystal polyester resin material that is easily plated. This method is not suitable for forming fine circuits.

The substrate thus formed is plated on only the circuit forming portion (a) by plating the surface thereof, so that a desired circuit can be formed and provided on the substrate.

In the present invention, in order to strengthen the adhesion of the plating, it is possible to perform a surface treatment such as etching on the circuit portion to be plated at an appropriate stage.

The liquid crystalline polyester is generally difficult to plate when an inorganic filler as described below is not added.
It can be used as a material. Also, make this easy plating,
In order to use the mold (a) of the present invention as a material,
Periodic Table Group II element and its oxide, sulfate, phosphate, silicate, carbonate and one selected from the group consisting of aluminum, silicon, tin, antimony, bismuth element and their oxides, and palladium chloride Alternatively, it can be achieved by blending two or more kinds of inorganic fillers.

Examples of such inorganic fillers include oxides such as magnesium oxide, calcium oxide, barium oxide and zinc oxide, magnesium phosphate, calcium phosphate, barium phosphate, zinc phosphate, magnesium pyrophosphate, calcium pyrophosphate, and other phosphates, and sulfuric acid. Sulfates such as magnesium, calcium sulfate, barium sulfate, magnesium silicate, calcium silicate,
Silicates such as aluminum silicate, kaolin, talc, clay, diatomaceous earth, wollastonite, magnesium carbonate,
Mention may be made of calcium carbonate, barium carbonate and zinc carbonate.

Although the tensile strength and the like of such a composition are slightly lowered, the heat resistance thereof is hardly lowered. Further, since it is essentially a liquid crystalline polyester, there is no inconvenience that it adheres well to the difficult-to-plate portion and is displaced by a temperature change or the like, resulting in a gap.

Generally called engineering plastics have good heat resistance and high strength, but when actually used for the purpose of the present invention, polysulfone, polyethersulfone, polyetherimide, etc. have heat resistance, In particular, the heat resistance of solder is insufficient, and polyphenylene sulfide and polyether ether ketone have sufficient heat resistance, but the peeling strength of the plating of the attached circuit part is weak and it is not practical. On the other hand, the liquid crystalline polyester has sufficient heat resistance, especially solder heat resistance as described above, and also has sufficiently practical peel strength.

Specifically, the liquid crystalline polyester is a melt-processable polyester having a property that polymer molecular chains have a regular parallel arrangement in a molten state.
The state in which the molecules are arranged in this way is often referred to as a liquid crystal state or a nematic phase of a liquid crystalline substance. The liquid crystal state, that is, the presence of the anisotropic molten phase can be confirmed by the presence or absence of optical anisotropy using a DC polarizer.

The polymer exhibiting an anisotropic phase used in the present invention is preferably an aromatic polyester and an aromatic polyesteramide, and a preferable example is also an aromatic polyester and a polyester partially containing the aromatic polyesteramide in the same molecular chain. Specific examples of the compound forming the constituent part and specific examples of the polyester forming the anisotropic molten phase which is preferable for use in the present invention are described in JP-A-61-69866.

Particularly preferred are aromatic polyesters and aromatic polyesteramides having at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids, aromatic hydroxyamines and aromatic diamines as a constituent component.

More specifically, 1) Polyester consisting only of aromatic hydroxycarboxylic acid 2) a) Aromatic hydroxycarboxylic acid and b) One or more kinds of aromatic dicarboxylic acid and alicyclic dicarboxylic acid and c) Aroma Group diol, alicyclic diol, polyester composed of one or more of aliphatic diol 3) a) aromatic hydroxycarboxylic acid, aromatic hydroxyamine, aromatic amine and b) aromatic dicarboxylic acid, alicyclic A polyester amide consisting of one or more aromatic dicarboxylic acids 4) a) an aromatic hydrocarboxylic acid, an aromatic hydroxyamine, an aromatic diamine and b) an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid or Examples thereof include polyesteramides composed of two or more kinds and c) one or more kinds of aromatic diols, alicyclic diols, and aliphatic diols. It

Specific examples include those having the following structures.

[Effects of the Invention] The present invention has a high level of function as an electric circuit by taking advantage of the characteristics of liquid crystalline polyester such as high strength, heat resistance and low linear expansion coefficient.

That is, since the liquid crystalline polyester is originally high in strength, it maintains sufficient strength as a substrate even if an inorganic filler is blended, and also with respect to heat resistance, for example, solder heat resistance of 260 seconds to 280 ° C. for 10 seconds is achieved, Since the plated and non-plated parts are essentially the same resin, the adhesion between them is also good, and the coefficient of linear expansion is the closest to that of metal in plastics. Peeling due to the difference in thermal expansion hardly occurs, and high functions such as high adhesion can be maintained.

Further, the liquid crystalline polyester has a good fluidity and is advantageous in that it can precisely mold even fine line portions. Incidentally, the method as described above, that is, one predetermined mold (easy-plating portion) (a) as in the present invention is injection-molded and then placed in another injection-molding die to make one predetermined mold. When performing the operation of injection molding the mold (hard plating part) (b),
If (a) has burrs, the shape of the circuit part will be disturbed, and it may happen that a substrate having a circuit pattern as originally designed cannot be obtained. However, the liquid crystalline polyester has good fluidity. Since the molded product has a characteristic that no burr is generated, such a phenomenon does not occur at all in the present invention.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Examples 1 to 6 The above-mentioned liquid crystalline polyesters A to F were used for the hard-to-plate portions, and 50 parts by weight of barium sulfate was added to 100 parts by weight of the liquid-crystalline polyester resins A to F, respectively, for the easily plated portions. The electric wiring board shown in FIGS. 1 and 2 was manufactured by using so-called two-color injection molding. When this was chemically plated with copper by an ordinary method, an electric wiring pattern as designed was formed.

When this was repeatedly subjected to a cooling / heating test at 150 ° C. for 10 minutes and −20 ° C. for 10 minutes, neither peeling nor disconnection of the plated portion of the sample was observed.

Comparative Example 1 A substrate was prepared, plated and tested in the same manner as in Example 1 except that polyetheretherketone was used instead of the liquid crystalline polyester resin.

As a result, 10 out of 20 samples had peeling or disconnection.

[Brief description of drawings]

FIG. 1 is a plan view of the substrate of the present invention, and FIG. 2 is II- of FIG.
It is a II line sectional schematic view. 1 ... Electrical circuit board 2 ... Circuit part 3 ... Non-circuit part 4 ... Hole 5 ... Circuit formation part that appears on the board surface 6 ... Coupling part

Claims (2)

[Claims] 1. A preformed mold formed of a thermotropic liquid crystalline polyester resin material exhibiting anisotropy when easily melted, and (b) Anisotropy when melted, which is difficult to plate. And a predetermined mold formed of the thermotropic liquid crystalline polyester resin material showing the above, (a) and (b) above are on the surface of the molded article, and (a) is a pattern of an electric circuit. A method of manufacturing an electric circuit board, characterized in that the board is integrally injection-molded by two-color injection molding so as to form a metal plate, and the pattern of the electric circuit is directly metal-plated. 2. A thermotropic liquid crystalline polyester resin material exhibiting anisotropy when melted, which is easy to plate, a thermotropic liquid crystalline polyester which exhibits anisotropy when melted, an element of Group II of the periodic table and its oxide, and sulfuric acid. Compositions containing one or more inorganic fillers selected from the group consisting of salts, phosphates, silicates, carbonates, aluminum, silicon, tin, antimony, bismuth elements and their oxides, and palladium chloride. A thermotropic liquid crystalline polyester resin material which is made of a material and exhibits anisotropy when melted, which is difficult to plate, and which is composed of a thermotropic liquid crystalline polyester which does not contain the inorganic filler and exhibits anisotropy when melted. Item 1. A method of manufacturing an electric circuit board according to item 1.