JPH11307904A - Molded circuit component and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a manufacturing process and enable cost reduction. SOLUTION: A wiring sheet 5 in which a wiring pattern 2 is previously formed on at least one surface of a liquid crystal polymer film 1, and a three- dimensional structure molded object 7 composed of resin are integrally formed at the time of molding of the object 7. The liquid crystal polymer film 1 excellent in dimensional stability at the time of heating, heat resistance and adhesion is used for the wiring sheet 5, so that formation of the wiring pattern 2 is facilitated. As a result a manufacturing process is simplified and a molded circuit component 10 capable of cost reduction can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded circuit component such as an internal component of a cellular phone, which has a mechanical and electrical function in which a circuit, a connector, a shield and the like are integrated in a housing, and a method of manufacturing the same. About.

[0002]

2. Description of the Related Art Printed circuit boards, which have been widely used in electric and electronic equipment, are laminated boards made of thermosetting resin such as paper phenol or glass epoxy, and are limited to flat plates. Post-processing such as plating, drilling, chamfering, and punching is required.

[0003] On the other hand, current electronic and electric parts often have a three-dimensional mechanical shape formed of a plastic molded body, and various parts are incorporated on the molded body in many cases.
For example, a three-dimensional molded body is formed by injection molding, a rigid board or a flexible board is fixed as a separate component on the board by screwing or bonding, and connectors and switches are incorporated as separate components on the board. .

[0004] In recent years, there is a component in which an electromagnetic wave shield is formed by a lead frame, vapor deposition, or the like as much as possible in order to prevent electromagnetic waves from being imposed on electric equipment or the human body from being affected by electromagnetic waves.

In the development of these recent parts, the development of a part manufacturing technique in which the number of parts is reduced, the number of steps for integration and assembly is reduced, and steps such as bonding and evaporation are reduced. Practical methods have also begun to apply wiring patterns to the inside of plastic housings such as electric appliances and the surfaces of plastic parts.
It is called CB (Molded Circuit Board). A group of devices provided with conductivity is MID (Molded Interc
onnection Device).

[0006] The above-mentioned method of manufacturing the MCB can be roughly classified into (1) a method of applying a wiring pattern after molding, (2) a two-shot method using a two-color molding method, and (3) a method of transferring a wiring pattern simultaneously with molding. Separated.

A specific example of the method of (1) for providing a wiring pattern after molding is as follows. That is,
After injection molding a resin mixed with a plating catalyst, the entire surface of the molded product is covered with electroless copper plating, and a resist is applied to form a wiring pattern. Thereafter, the copper plating on the portion not covered with the resist is removed by etching, and the resist is further removed to form a circuit. As another method, a molded article is subjected to a chemical treatment for increasing the adhesion of copper plating, and then coated with a liquid containing an ultraviolet-sensitive catalyst. After the molded article is dried, when the wiring pattern is exposed using ultraviolet light, the exposed portion is free of metal plating. Thereafter, the molded article is electrolessly plated to form a circuit on the surface.

Next, a specific example of the two-shot method utilizing the two-color molding method of the above (2) is as follows. That is, 1
It is molded with a resin containing a catalyst at the shot. At this time, a through-hole and a projection portion serving as a circuit are formed. Then
After this product is manually or automatically moved to another mold or another cavity in the same mold, the second shot is made of resin that does not enter the catalyst. Cover the surface. When a treatment for increasing the adhesion of plating and a treatment for activating the catalyst are performed on the exposed portion and electroless copper plating is performed, only the exposed portion of the resin containing the catalyst is plated with copper, and a circuit is formed.

The method of transferring a wiring pattern simultaneously with the molding in the above (3) utilizes an in-mold transfer molding method which is one of the painting moldings. Specifically, a wiring pattern is formed in advance on a heat-resistant carrier film using a copper foil, a conductive paste, or the like, and only the circuit pattern is strongly transferred to a molded product in a mold during injection molding. The film is peeled from the molded article.

[0010]

However, the circuit forming techniques according to the two methods (1) and (2) have a problem that the manufacturing process is complicated and the equipment configuration is complicated. There is a limit to cost reduction, which is the original purpose of the system.

On the other hand, although the method (3) can simplify the manufacturing process as compared with the above two methods,
Since the time required to peel off the carrier film is required and the expensive carrier film is peeled off and discarded, there is also a limit in cost reduction, which is the original purpose of the method for producing MCB.

Further, as a plastic material used in the method of manufacturing the MCB, there is a particularly strong demand for a solder surface mount component, and a thermoplastic liquid crystal polymer has been frequently used as a material capable of meeting this requirement. However, in the method of transferring the wiring pattern simultaneously with the molding in the above (3),
In fact, there was virtually no carrier film having the same heat resistance as the thermoplastic liquid crystal polymer.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a molded circuit component which simplifies a manufacturing process and enables cost reduction.

[0014]

Means for Solving the Problems The present inventors have proposed a film formed from a polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as a liquid crystal polymer) (hereinafter referred to as a liquid crystal polymer). Investigating in detail the production of the film), it was found that the above-mentioned problems could be solved by making it possible to provide a useful liquid crystal polymer film having excellent dimensional stability upon heating, and excellent heat resistance and adhesion. Thus, the present invention has been completed.

The molded circuit component of the present invention is characterized in that a wiring sheet in which a wiring pattern is previously formed on at least one side of a film molded from a liquid crystal polymer and a molded article having a three-dimensional structure made of resin are formed at the time of molding of the molded article. It is characterized by being integrated.

As a method of forming a wiring pattern on the liquid crystal polymer film, (A) a method of bonding a liquid crystal polymer film and a conductive metal such as a copper foil by hot pressing and then forming a wiring pattern by chemical treatment or the like. (B) a method in which a wiring pattern is printed on a liquid crystal polymer film with a conductive paste such as a silver paste through a printing mask on which the wiring pattern is drawn and thermally cured to form the wiring pattern; A method of forming a wiring pattern using the same and transferring the wiring pattern to a softened liquid crystal polymer film by a roll press or a flat plate press.

In the molded circuit component of the present invention, since the liquid crystal polymer film has excellent dimensional stability and adhesion when heated, it is easy to form a wiring pattern by hot pressing in the method (A). Because it has excellent adhesion,
The formation of a wiring pattern by printing or transfer in the methods (B) and (C) is facilitated, and as compared with the above-described conventional method, manufacturing is facilitated and cost reduction can be achieved.

In the present invention, a wiring sheet having a wiring pattern formed on both sides as well as on one side of the liquid crystal polymer film may be used. In this case, the wiring pattern can be formed at a high density.

In the present invention, the wiring sheet may have a protruding portion protruding from the outer edge of the three-dimensionally formed body. In this case, by forming a wiring pattern on the protruding portion, electrical connection using the wiring pattern of the protruding portion is also possible.

The liquid crystal polymer that can be used in the molded circuit component of the present invention is not particularly limited. For example, a known thermotropic liquid crystal derived from the compounds shown in the following Tables 1 to 4 and their derivatives (raw material compounds) Mention may be made of polyesters and thermotropic liquid crystal polyesteramides. Typical examples thereof include copolymers (a) to (e) having the structural units shown in Table 5. However, it goes without saying that a suitable combination of repeating units is required to obtain a liquid crystal polymer. Note that additives and various fillers may be mixed with the liquid crystal polymer as long as the physical properties of the film are not impaired.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

[Table 4]

[0025]

[Table 5]

The film used in the present invention is obtained by extruding a liquid crystal polymer. Although any extrusion method is used for this purpose, the well-known T-die method, inflation method, etc. are industrially advantageous. In particular, in the inflation method, in the machine axis direction of the film (hereinafter, MD)
Direction), stress is applied in a direction orthogonal to the MD direction (hereinafter referred to as a TD direction).
It is possible to obtain a film in which mechanical properties and thermal properties are balanced between the TD direction and the TD direction.

Among them, a liquid crystal polymer film having a degree of molecular orientation SOR of 1.3 or less has a better balance of mechanical properties and thermal properties between the MD direction and the TD direction, and is therefore more practical. .

Here, the degree of molecular orientation SOR (Segment Orien
tation Ratio) is an index that gives the degree of molecular orientation for the segments that compose the molecule.
Unlike R (Molecular Orientation Ratio), it is a value irrelevant to the thickness of the object. This molecular orientation degree SOR is calculated as follows.

First, in a well-known microwave molecular orientation measuring instrument, a liquid crystal polymer film is inserted into a microwave resonant waveguide such that the film surface is perpendicular to the traveling direction of the microwave. The electric field intensity (microwave transmission intensity) of the transmitted microwave is measured. Then, based on the measured value, an m value (referred to as a refractive index) is calculated by the following equation. m = (Z ₀ / △ z) × (1−ν _max / ν ₀ ) where Z ₀ is a device constant, Δz is the average thickness of the object, and ν _max
Is the frequency that gives the maximum microwave transmission intensity when the frequency of the microwave is changed, and v ₀ is the frequency that gives the maximum microwave transmission intensity when the average thickness is zero (that is, when there is no object).

Next, when the rotation angle of the object with respect to the vibration direction of the microwave is 0 °, that is, the vibration direction of the microwave and the direction in which the molecules of the object are most oriented, and the minimum microwave transmission m ₀ to m value when the direction that gives strength meets a m value when the rotation angle is 90 ° as m _90, orientation ratio SOR is calculated by m ₀ / m _90.

The required degree of molecular orientation SOR naturally depends on the field of application of the liquid crystal polymer film of the present invention. However, when SOR ≧ 1.5, the film becomes hard due to a remarkable deviation in the orientation of the liquid crystal polymer molecules. And easily torn in the orientation direction. In the case of a normal wiring sheet that requires dimensional stability and flexibility (adhesion) such as no warpage during heating, it is preferable that SOR ≦ 1.3, and in particular, warpage during heating is substantially reduced. In the case of a precise wiring sheet that needs to be eliminated, it is desirable that SOR ≦ 1.03.

On the other hand, the raw material resin of the molded article having a three-dimensional structure which can be used in the molded circuit component of the present invention is not particularly limited. For example, polystyrene, acrylonitrile / butadiene / styrene copolymer, polyphenylene oxide, polycarbonate, polysulfone , Polyether imide, polyether sulfone, polyphenylene sulfide, liquid crystal polymer, polyimide, polyether ether ketone, and the like. Above all,
The liquid crystal polymer can be preferably used because it has features such as being less likely to generate burrs during molding, being excellent in heat resistance such as thermal dimensional stability, and having low moisture absorption and high reliability. In addition, you may mix various additives and various fillers with these resins.

Next, a method for manufacturing a molded circuit component of the present invention will be described. A wiring sheet having a wiring pattern formed on at least one side of the liquid crystal polymer film in advance is set in a mold, and a resin for a three-dimensionally formed body is injection-molded on the wiring sheet. The wiring sheet and the molded body are integrated during the molding. After cooling, the integrated molded product is taken out to obtain a desired molded circuit component. Since the molded circuit component of the present invention uses a liquid crystal polymer film having excellent dimensional stability, heat resistance, and adhesion for the wiring sheet, the wiring patterns (A) to (C) can be easily formed. Compared with the method, the manufacturing process can be simplified and the cost can be reduced. In addition, the liquid crystal polymer film used acts as an appropriate elastic body at the mold temperature, so that the airtight state is improved at a normal mold clamping pressure. For this reason, it is also possible to obtain a molded circuit component in which the liquid crystal polymer film (insulating sheet) having the wiring pattern formed on the surface has the above-mentioned protruding portion.

In the manufacture of the molded circuit component, it is desirable that the liquid crystal polymer film having the wiring pattern formed on the surface thereof has higher heat resistance, especially the melting point, than that of the molded article having the three-dimensional structure. If the heat resistance, particularly the melting point, of the molded article having a three-dimensional structure is higher than that of the liquid crystal polymer film, the temperature of the mold may be lowered to a temperature at which the form of the liquid crystal polymer film can be maintained. In addition, the heat treatment of the liquid crystal polymer film increases the melting point, so that the reliability of the molded circuit component can be further improved. To explain an example of the heat treatment, a liquid crystal polymer film having a melting point of 283 ° C. is heated to 260 ° C.
For 5 hours, the melting point of the film becomes 320 ° C. This treatment can also be applied to a three-dimensional structure formed using a liquid crystal polymer.

[0035]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing a manufacturing process of a molded circuit component according to one embodiment of the present invention. The molded circuit component 10 is manufactured by injection-molding a molded article 7 having a three-dimensional structure on a wiring sheet 5 in which a wiring pattern 2 is formed on a liquid crystal polymer film 1 and integrating them.

As shown in FIG. 1A, first, the wiring sheet 5
Has a wiring pattern 2 formed on one surface of a liquid crystal polymer film 1 in advance. In this example, the wiring pattern 2a is also formed on the outer edge of the wiring sheet 5. The wiring sheet 5 includes a mold 3 including a movable mold 3 and a fixed mold 4.
4, the surface on which the wiring pattern 2 is formed is set on the movable mold 3 side, but may be set on the fixed mold 4 side. At this time, the outer edge of the wiring sheet 5 protrudes from the dies 3 and 4. Next, as shown in FIG. 1 (b), a resin 7 is injection-molded from the hole 4a of the fixed mold 4 onto the back surface of the wiring sheet 5 to form a molded body 7 having a three-dimensional structure. The wiring sheet 5 and the molded body 7 are
The molding 7 is integrated at the time of molding. As shown in FIG. 1C, after cooling, the integrated molded product is taken out of the dies 3 and 4 to obtain a desired molded circuit component 10.

In the present invention, since the liquid crystal polymer film 1 having excellent dimensional stability, heat resistance and adhesion as described above is used for the wiring sheet 5, the formation of the wiring pattern 2 becomes easy, and it can be obtained by the conventional method. It is possible to obtain a molded circuit component 10 that simplifies a manufacturing process that has not been performed and enables cost reduction. In FIG. 1B, the liquid crystal polymer film 1 can be in a softened state by the heat of the three-dimensional structure molded body 7, so that the wiring pattern 2 formed on the surface is formed inside the liquid crystal polymer film 1. As shown in FIG. 1C, a molded circuit component 10 having a smooth surface can be provided. Further, as shown in FIG. 1C, electrical connection using the wiring pattern 2a of the protruding portion 5a at the outer edge is also possible. Note that the protruding portion 5a may not be provided in advance, and the provided protruding portion 5a may be cut off as necessary.

It is to be noted that an adhesive layer may be inserted beforehand into the fixed mold 4 and used, or the liquid crystal polymer film 1 to be used can be used as an adhesive layer as it is. In particular, the latter method is a method that can be performed in place of the molding method that conventionally required peeling as a carrier tape, and is particularly useful because not only the time required for peeling can be saved, but also a remarkable improvement in adhesion can be expected. is there.

In this embodiment, the wiring sheet 5
Although the wiring pattern 2 is formed on one side of the liquid crystal polymer film 1, it may be formed on both sides. In this case, the wiring pattern can be formed at a high density, and the size of the molded circuit component can be reduced.

[0040]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Reference Example 1 p-Hydroxybenzoic acid and 6
-Hydroxy-2-naphthoic acid copolymer having a melting point of 3
A liquid crystal polymer at 30 ° C. was melt-extruded, and a film having a thickness of 50 μm and a degree of molecular orientation SOR of 1.03 was obtained by inflation molding. Next, an electrolytic copper foil (length 25 cm, width 10 cm, thickness 35 μm), the liquid crystal polymer film (length 20 c
m, width 5 cm), and electrolytic copper foil (length 25 cm, width 1)
0 cm and a thickness of 35 μm) were sequentially stacked so that the center in the length direction and the center in the width direction of each material coincided. When the inside of the chamber of the vacuum heat press was evacuated and then heated to 340 ° C., it was pressed at a pressure of 30 kg / cm ² for 5 minutes. Subsequently, the temperature was lowered to 50 ° C., and after releasing the vacuum and the pressure, the press-bonded body was taken out. Chemically dissolve and remove all of the copper foil on one side of the obtained crimped body, and leave the copper foil on the opposing opposite side, leaving the copper foil that will be the wiring pattern of the finally obtained molded circuit component, other copper foil All copper foil in the area was chemically dissolved and removed. This is a wiring sheet for pattern A.

Reference Example 2 p-Hydroxybenzoic acid and 6
-Hydroxy-2-naphthoic acid copolymer having a melting point of 2
A liquid crystal polymer having a temperature of 83 ° C. was melt-extruded, and a film having a thickness of 50 μm and a degree of molecular orientation SOR of 1.05 was obtained by inflation molding. Next, a wiring pattern for using the molded circuit component finally obtained as an optical module case was formed on one surface of the film with a silver paste. This is a pattern B wiring sheet.

Reference Example 3 p-Hydroxybenzoic acid and 6
-Hydroxy-2-naphthoic acid copolymer having a melting point of 2
30% by weight of glass fiber was kneaded with a liquid crystal polymer at 83 ° C. and melt-extruded to obtain a pellet-shaped resin for injection molding.

Example 1 In FIG. 1A, a movable mold at 100 ° C. was set so that the wiring pattern 2 surface of the wiring sheet 5 of the pattern A obtained in Reference Example 1 faces the movable mold 3. 3 and a fixed mold 4 at 100 ° C. next,
As shown in (b), the mold is closed, and the injection pressure is 200 kg / c.
The resin 7 of Reference Example 3 was injection molded at m ² and an injection speed of 1 m / min. As shown in (c), the molded circuit component 10 taken out after cooling has the wiring sheet 5 and the molded article 7 having the three-dimensional structure including the part at the rising angle of 90 ° and the part of the overhang.
Were completely integrated, and it was confirmed that the adhesive force between the copper foil forming the wiring pattern 2 and the liquid crystal polymer film 1 was at a level at which there was no practical problem. In addition, these conditions are that the molded circuit component 10 is placed in a 280 ° C.
The same is true even after dipping for 2 seconds, confirming that it has good heat resistance.

Example 2 A molded circuit component was produced in the same manner as in Example 1 except that the wiring sheet of Pattern B obtained in Reference Example 2 was used. The obtained molded circuit component is completely integrated with the above-mentioned wiring sheet and the three-dimensionally formed molded body, including the part having a rising angle of 90 ° and the part of the overhang, and is a copper foil for forming a wiring pattern. It was also confirmed that the adhesive strength between the film and the liquid crystal polymer film was at a level having no practical problem. These conditions were the same even after the molded circuit component was immersed in a 260 ° C. solder bath for 60 seconds, and it was confirmed that the molded circuit component had good heat resistance.

Example 3 The molded circuit component obtained in Example 2 was heated at 260 ° C. for 5 hours,
For 60 seconds. According to subsequent observations, the wiring sheet and the molded article having the three-dimensional structure are completely integrated, and the adhesive strength between the copper foil and the liquid crystal polymer film forming the wiring pattern is at a level that does not cause any practical problem. That was confirmed.

[0047]

According to the present invention, as is apparent from the above-described embodiment, a wiring pattern can be formed by using a liquid crystal polymer film having excellent dimensional stability during heating, heat resistance and adhesion as a wiring sheet. By integrating the wiring sheet with the molded body having the three-dimensional structure, a highly reliable molded circuit component can be obtained with high productivity and at low cost.

[Brief description of the drawings]

FIGS. 1A to 1C are side views showing a manufacturing process of a molded circuit component according to an embodiment of the present invention.

[Explanation of symbols]

1: Liquid crystal polymer film, 2: Wiring pattern, 3, 4
... Mold, 5 ... Wiring sheet, 5a ... Protruding part, 7 ... Molded body, 10 ... Molded circuit part.

Claims (4)

[Claims] A wiring sheet in which a wiring pattern is previously formed on at least one surface of a film formed from a polymer capable of forming an optically anisotropic molten phase, and a molded article having a three-dimensional structure made of a resin, A molded circuit component, which is integrated when a molded product is molded. 2. The molded circuit part according to claim 1, wherein the molded article having the three-dimensional structure is made of a polymer capable of forming an optically anisotropic molten phase. 3. The molded circuit component according to claim 1, wherein the wiring sheet has a protruding portion protruding from an outer edge of the molded article having the three-dimensional structure. 4. The method for producing a molded circuit component according to claim 1, wherein at least one surface of a film molded from a polymer capable of forming an optically anisotropic molten phase has a wiring pattern. Forming a molded circuit part by injection molding and integrating the molded article having the three-dimensional structure on the wiring sheet on which the molded circuit part is formed.