JPH1117314A - Molded circuit body and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molded circuit body and a method of manufacturing the circuit body which forms a high-precision and high-density conductor wiring pattern, with high reliability with respect to conductor wiring omission, and which enables a large current capacity, in a recess of an insulating substrate having a cubic shape. SOLUTION: Conductor wiring patterns 4 are formed by coating a temporary substrate 1 with a photo-curing resin, then performing exposure and development so as to form an inverted pattern of the conductor wiring pattern, and performing electric plating on electric paths 3 formed between the inverted patterns. Next, the obtained temporary substrate is placed in a metal mold, then the insulating substrate is formed on the forming surface of the wiring pattern, then removing the temporary substrate 1 from the molded body, and transferring an insulating mask 2 with the conductor wiring pattern onto the surface of the molded body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded circuit having a conductor wiring pattern formed on an insulating substrate and a method of manufacturing the same.
The present invention relates to a molded circuit having a highly accurate and high-density conductor wiring pattern formed in a concave portion of an insulating substrate having a three-dimensional shape, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Heretofore, printed wiring boards have generally been formed by forming a conductor wiring pattern on a flat insulating substrate. However, in recent years, three-dimensional shapes such as a wiring box having a wiring circuit formed inside a box-formed product and a connector connecting portion have been required due to a need for increasing the mounting efficiency of circuit components and simplifying an assembly process. A molded circuit having a conductor wiring pattern formed in a concave portion of an insulating substrate is used.

Various methods have already been disclosed as a method of manufacturing a molded circuit body for forming a conductor wiring pattern in a concave portion of an insulating substrate having such a three-dimensional shape. For example, Japanese Patent Application Laid-Open No. 64-86590 discloses that a mask of an inverted pattern is formed on a metal temporary base material, a conductor wiring pattern is formed in a gap of the mask by electrolytic plating, and then,
After disposing the temporary base in a mold and forming an insulating substrate by injection molding or the like on the temporary substrate surface on which the mask and the conductor wiring pattern are formed, the temporary base and the mask are removed from the insulating substrate. Thus, a method is disclosed in which a conductor wiring pattern is transferred to a concave portion of an insulating substrate having a three-dimensional shape to form a molded circuit body.

Japanese Patent Application Laid-Open No. Sho 63-299295 discloses that the adhesiveness with the mold is small over the entire surface of the mold for resin molding.
And a base plating film of the same quality as the conductor wiring pattern is provided,
A resist is printed thereon to form a mask of an inverted pattern, a conductor wiring pattern is formed in a gap of the mask by a plating method, and then the resist is removed, and then the insulating substrate is formed using such a mold. A method of transferring a conductor wiring pattern formed on the surface of a mold to a concave portion of an insulating substrate by molding the same by injection molding or the like. In this method, in order to secure insulation between the conductor wiring patterns, the underlying plating film is dissolved and removed by soft etching after molding to expose the conductor wiring patterns.

Further, Japanese Patent Application Laid-Open No. 2-67114 discloses that a conductor foil is stuck on a film, and a chemical conductor is repeatedly formed into a rectangular conductor wiring pattern body, and the conductor wiring pattern body is further etched. After forming a conductive wiring pattern having a stepped undercut portion, the bonding position of the film is reversed to form a wiring circuit forming film, which is placed in a predetermined mold, and an insulating base material is formed on the film by injection molding or the like. Is disclosed, whereby a conductor wiring pattern is transferred to a concave portion of an insulating base material. In this method, by providing an undercut portion in the conductor wiring, the resin flows around the undercut portion during molding, thereby preventing the conductor wiring from falling off.

[0006]

However, the method disclosed in the first Japanese Patent Application Laid-Open No. 64-86590 is a method of removing a mask together with a temporary base from a molded product after injection molding. The surface of the product and the surface of the conductor wiring are not flush with each other, and a step is generated between the resin and the conductor wiring by the thickness of the removed mask. Therefore, when a connector is manufactured by this method, for example, there is a problem in that the connector is caught between the connector pins when the connector is inserted and withdrawn, and the contact portion is damaged.

On the other hand, if only the mask is removed from the temporary base material on which the conductor wiring pattern is formed, and then the resin is molded, the surface of the molded product and the surface of the conductor wiring become the same plane, and the above-mentioned problem can be avoided. However, there is a problem that since a small amount of resin flows between the mold and the conductor wiring, the cleanliness of the surface of the conductor wiring pattern is reduced, and the reliability for electrical connection is reduced.

Further, the second Japanese Patent Application Laid-Open No. 63-299295
The method disclosed in Japanese Patent Application Laid-Open Publication No. H11-163873 is a method in which a base plating film is transferred to a resin surface together with a conductor wiring pattern, and then the base plating film is removed by soft etching or the like. It is difficult to control the roughness. Therefore, for example, when a connector is manufactured, there is a problem that the surface of the conductor wiring in an excessively etched portion is lower than the surface of the resin, and a contact failure occurs with the connector pin.

Furthermore, the method disclosed in the last Japanese Patent Application Laid-Open No. 2-67114 has a problem in that the height of the undercut portion is low, so that the resin is insufficiently wrapped around, and the reliability against falling off is reduced. Was. In addition, when the distance between the conductor wirings is reduced, the resin is not sufficiently wrapped around, so that there is a problem that high-density wiring is difficult.
Further, since the undercut portion is formed by the etching method, the cross-sectional area of the conductor foil attached on the film is reduced, and there is a problem that the current capacity of the conductor wiring is reduced.

The problem to be solved by the present invention is to make it possible to form a high-precision and high-density conductor wiring pattern in a concave portion of an insulating substrate having a three-dimensional shape, and to cause damage when connecting to another component. It is an object of the present invention to provide a molded circuit body which does not impair the conductivity of the surface of a conductor wiring, has high reliability against falling off, and can have a large current capacity, and a method for manufacturing the same.

[0011]

Means for Solving the Problems In order to solve this problem, a molded circuit body according to the present invention has a conductor wiring pattern formed on a surface of an insulating substrate, and the surface of the insulating substrate has The gist is that an insulating mask is provided in a gap between the conductor wiring patterns so as to be substantially flush with the surface of the conductor wiring patterns.

According to the molded circuit having the above structure, the exposed surface of the conductor wiring is flat, so that when the obtained molded circuit is connected to another component, the contact portion is not damaged. Also, the assembly process can be simplified.

In the method of manufacturing a molded circuit body according to the present invention, a step of covering a region other than the conductor wiring pattern region on the surface of the conductive temporary substrate with an insulating mask, and a step of not covering the region with the insulating mask. Forming a conductive wiring pattern on the conductive wiring pattern area by electroplating, forming an insulating substrate on the surface on which the conductive wiring pattern is formed, and leaving the conductive wiring pattern and the insulating mask on the insulating substrate. Removing only the temporary substrate.

According to the method of manufacturing a molded circuit having the above-described structure, first, a region other than the conductor wiring pattern region in the surface of the temporary substrate is covered with the insulating mask. Next, using the temporary substrate as a cathode, a conductor wiring pattern is formed by electroplating in a conductor wiring pattern area not covered by the insulating mask. Then, the temporary substrate is arranged on a mold so that the resin is molded on the surface of the temporary substrate on which the insulating mask and the conductor wiring pattern are formed, and the insulating substrate is formed on the surface on which the conductor wiring pattern is formed by means such as injection molding. Is molded. After the molding, the molded product is taken out from the mold and only the temporary substrate is mechanically peeled off, whereby a molded circuit body having the conductive mask and the insulating mask transferred to the concave portion of the insulating substrate is obtained.

Thus, the insulating mask is transferred integrally with the conductive wiring pattern onto the insulating substrate, so that the step generated between the insulating substrate and the conductive wiring is eliminated by the insulating mask disposed between the conductive wirings. As a result, it is possible to obtain a molded circuit body in which the surfaces of the conductor wiring and the insulating mask are kept flat.

In addition, since the insulating mask is transferred onto the insulating substrate together with the conductive wiring pattern, when the insulating substrate is formed, the mask blocks the resin from wrapping around the conductive wiring surface and keeps the conductive wiring surface clean. It is. As a result, a part of the conductor wiring is not insulated after molding, and a molded circuit having high reliability for electrical connection can be obtained.

Here, it is particularly preferable that the insulating mask is made of a photocurable resin material. If a photocurable resin material is used as the insulating mask, a photolithography method can be employed in the pattern forming step, so that a high-precision, high-density wiring pattern can be formed, and the pattern forming step can be simplified. . In addition, the photocurable resin has sufficient hardness after curing, and the cured resin protects the conductor wiring pattern. This is because it can be reduced. As the photocurable resin material, for example, photosensitive polyimide,
A photosensitive epoxy, a photosensitive acrylic resin or the like is suitable, but not limited thereto.

The thickness of the insulating mask is preferably at least 5 μm. If the thickness of the insulating mask is 5 μm or more, the mechanical strength of the insulating mask is ensured, so that problems such as deformation of the conductor wiring pattern in the manufacturing process of the molded circuit body can be avoided. Further, before forming the insulating substrate, the surface of the insulating mask may be roughened by using an appropriate means such as etching with potassium permanganate. This is because, when the resin enters the uneven portion of the roughened insulating mask, an anchor effect acts between the resin and the insulating mask, and high adhesive strength can be obtained without using an adhesive.

It is particularly desirable that the base of the conductor wiring is buried in the insulating substrate. That is, if the base of the conductor wiring protrudes from the insulating mask toward the insulating substrate, and the tip is buried in the insulating substrate,
This is because a frictional force is generated between the buried portion and the insulating substrate surrounding the buried portion, and it becomes a resistance against a force acting in a direction in which the conductor wiring drops.

The outer diameter of the conductor wiring portion embedded in the insulating substrate is larger than the outer diameter of the portion surrounded by the insulating mask, that is, the cross section of the conductor wiring has a mushroom shape. Especially desirable. If the cross section of the conductor wiring has a mushroom shape, the resistance to the conductor wiring falling off will be even greater, and the route for the molten resin to reach the surface will be narrower and longer, so that the resin will exude more during molding. This is because it becomes difficult to keep the conductor surface clean. Further, since the cross-sectional area of the conductor wiring is increased, the electric resistance of the conductor wiring is reduced, and a large current capacity can be achieved.

Furthermore, it is particularly desirable that the conductor wiring is formed of a metal layer formed by an electroplating method. This is because, according to the electroplating method, a highly accurate and high-density conductor wiring pattern can be formed. Also, compared to other methods such as a vapor deposition method and a conductive paste method, the resistance value of the obtained conductor wiring is remarkably low, large current capacity can be achieved, and high reliability is obtained. Because. here,
As a plating metal used for the conductor wiring, a metal having high conductivity such as copper, nickel, gold, and silver is preferable, but copper is particularly preferable in terms of price and electric conductivity. Examples of the plating bath used for the electrolytic copper plating include various plating baths such as a copper sulfate plating bath, a copper borofluoride plating bath, a copper cyanide plating bath, and a copper pyrophosphate plating bath. is not.

It is particularly desirable that the insulating substrate is made of a thermoplastic resin material. This is because a highly efficient molding method such as an injection molding method can be adopted, and a molded circuit body can be mass-produced at low cost. As the thermoplastic resin material, polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), polycarbonate (PC), polyamide 66 (PA66), liquid crystal polymer (LCP), and the like are preferable, but particularly limited to these. Not something.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows one embodiment of a method for manufacturing a molded circuit body according to the present invention in the order of steps.

FIG. 1A shows a temporary substrate (1) for forming a wiring pattern. The temporary substrate (1) serves as a substrate on which a conductor wiring pattern is formed,
It serves as a cathode when forming conductor wiring by electroplating. Therefore, the temporary substrate needs to be made of a conductive material. Usually stainless steel plate,
A metal plate such as an aluminum plate is used.

First, the surface of the temporary substrate (1) is polished flat, and an insulating mask (2) made of a photocurable resin is applied to the entire surface of one side to a predetermined thickness. FIG. 2B shows a state where the insulating mask (2) is applied to the temporary substrate (1). The thickness of the insulating mask (2) is to ensure mechanical strength.
The thickness is required to be 5 μm or more, but may be appropriately selected according to the use of the molded circuit body and the properties of the photocurable resin to be used.

Next, a photomask having an inverted pattern opposite to the conductor wiring pattern is prepared and placed on the temporary substrate (1) coated with the photocurable resin, and the area other than the conductor wiring pattern area is exposed. To cure the photocurable resin. After the photo-curable resin is cured, development is performed to remove the uncured photo-curable resin, whereby electric paths (3...) Are formed in the gaps of the insulating mask (2). FIG. 1 shows a state in which electric paths (3...) Are formed on the temporary substrate (1).
It is shown in (c).

The temporary substrate thus obtained was used as a cathode, immersed in a plating bath, and electroplating was performed.
..), Metal ions in the plating bath are precipitated, and conductor wirings (4...) Are formed. If the plating conditions are appropriately selected, the conductor wirings (4...) That have been deposited project from the electric paths (3...) Formed between the insulating masks (2) and project laterally. The cross section becomes mushroom-shaped. FIG. 1D shows a state where the mushroom-shaped conductor wiring is formed by the electroplating method.

When the conductor wirings (4...) Are formed on the temporary substrate (1), the temporary substrate (1) is taken out of the copper plating bath and washed. In this state, the resin may be immediately molded on the temporary substrate (1). However, if the temporary substrate is roughened with an appropriate etching solution such as an aqueous solution of potassium permanganate (KMnO ₄ ), the insulating property is reduced. This is preferable because the adhesive strength between the mask (2) and the resin molded thereon is improved. FIG. 1E shows a state in which the surface of the insulating mask (2) is roughened using an etching solution.

Next, using the temporary substrate (1) thus adjusted, an insulating substrate having a three-dimensional shape is formed. FIG. 1F shows a cross-sectional view of the mold immediately after molding. The lower mold (5) has an upwardly convex cross-sectional shape,
Also, the upper mold (6) has a concave cross-sectional shape below,
When both are overlapped, a cavity (7) corresponding to the shape of a molded circuit body as a final product is formed. Further, a gate (8) for pouring the molten resin into the cavity is provided at the center of the upper mold (6).

The resin is molded according to the following procedure. A temporary wiring board (1) having a conductive wiring pattern composed of conductive wirings (4...) And an insulating mask (2) formed on the surface thereof by the above-described method is used to form a conductive wiring pattern and an insulating mask (2). It is placed on the convex part of the lower mold (5) with the made surface facing up. Next, the upper mold (6) is placed on the lower mold (5) and fixed in the molding machine, and the molten resin is pressed into the mold from the gate (8). When the molten resin is pressed into the mold,
The resin is filled in the cavity (7), and the insulating mask (2) and the conductor wiring pattern formed on the surface of the temporary substrate (1) placed on the lower mold (5) are in close contact with the molten resin. .

After the injection of the resin is completed, the mold is cooled to solidify the resin, and then the lower mold (5) and the upper mold (6) are separated. At this time, the molded product remains fixed to the upper mold (6). Therefore, next, the molded body is extruded from the upper mold (6) using a pin (not shown), and the molded body and the upper mold (6) are separated. After the separation, when the temporary substrate (1) is mechanically peeled from the molded body, the insulating mask (2) and the conductor wiring (4.
A molded circuit body in which the conductor wiring pattern composed of ()) is transferred to the bottom surface of the concave portion of the molded body is obtained. The resulting molded circuit is shown in FIG.

(Example 1) According to the above-described procedure, a connector having a conductor wiring inside was manufactured. An aluminum plate was used as a temporary substrate, and a photocurable resin was applied thereon as an insulating mask to a thickness of 30 μm. As the photocurable resin, "Multiposit XP-9500CC" manufactured by Shipley Far East Co., Ltd. was used.

Next, a photomask having an inverted pattern opposite to the conductor wiring pattern was prepared, and an area other than the conductor wiring pattern area was exposed to light to cure the photocurable resin in the area. The exposure amount was 3000 mJ / cm ² .
After the photo-curing resin is cured, the developer developed by the company is heated to 35 ° C.
Spray on the photocurable resin surface for 90 seconds at the temperature of
An uncured portion of the photocurable resin was removed to form an electric path.

Using the temporary substrate thus obtained as a cathode, electrolytic copper plating was performed. Copper plating bath, copper pyrophosphate _{(Cu 2 P 2 O 7 ·} 3H 2 O) 85g / l, potassium pyrophosphate _{(K 4 P 2 O 7)} 240g / l, ammonia water 3m
1 / l copper pyrophosphate bath with a current density of 5 A /
Copper electroplating was performed under the conditions of m ² and a temperature of 55 ° C. 1.
After one hour, copper is deposited in the electric circuit formed on the temporary substrate, and the deposited copper protrudes from the insulating mask, and extends laterally, is 70 μm in height, and has a mushroom-shaped cross section. Was formed.

When the conductor wiring is formed in the electric circuit,
The temporary substrate was taken out of the copper plating bath and washed. Then
This was treated with a potassium permanganate (KMnO ₄ ) aqueous solution (trade name “Microetch 7” manufactured by Shipley Far East Co., Ltd.).
48 ”), the surface of the insulating mask was etched and roughened by immersion at 20 ° C. for 1 hour.

Next, an insulating substrate was formed using the obtained temporary substrate. As an insulating substrate material, a liquid crystal polymer (trade name “VECTRA A130”, glass fiber 3
0% added), and an injection molding method was employed for molding.
The injection molding conditions were a mold temperature of 100 ° C. and a molding temperature of 290.
~ 320 ° C.

The obtained connector was normal without any resin adhering to the conductor wiring. In addition, as a result of conducting a conduction test of the conductor wiring, it was found that the resistance was sufficiently low and the conductor wiring itself was not damaged. Further, when a continuity test was performed with the connector connected, no abnormality was found, and no poor contact was found in the contact portion with the connector pin.

The surface of the conductor wiring and the surface of the insulating mask were flat, and no visible irregularities were observed. When the obtained connector was subjected to a repeated insertion / extraction test, no damage was caused on the contact portion.

As described above, according to the present invention, a high-precision and high-density concave portion of an insulating substrate having a three-dimensional shape can be formed without damaging it at the time of connection with another component and without impairing the conductivity of the conductor wiring surface. It has been found that it is possible to easily obtain a molded circuit body on which a suitable conductor wiring pattern is formed.

The present invention is not limited to the above-described embodiment at all, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the connector is manufactured. However, the present invention is not limited to this. Not only the concave portion of the insulating substrate having a three-dimensional shape, such as a wiring box in which a wiring circuit is formed inside a box-shaped product, but also a concave portion is provided. The present invention is also applicable to a case where a circuit is formed on one or both sides of a flat insulating substrate. Further, it is also possible to manufacture a more three-dimensional molded circuit body by combining a plurality of temporary substrates having different heights as the temporary substrate. Furthermore, other metal plates such as a stainless steel plate are used as a temporary substrate, a copper plating bath such as a copper sulfate bath or another metal plating bath is used as an electroplating, a photocurable resin, a thermosetting resin for an insulating substrate. Even when another material is used as the resin, the same effect as in the above embodiment can be obtained.

[0041]

According to the molded circuit body and the method of manufacturing the same of the present invention, a part of the conductor wiring integrated with the molded body is exposed on the surface and the exposed surface of the conductor wiring is flat. Damage to the contact portion when it is connected to another component can be avoided, and electrical connection can be made simultaneously with connection, thereby simplifying the assembly process. Further, since the conductor wiring pattern and the insulating mask are integrally transferred onto the insulating substrate, it is possible to prevent the resin from wrapping around the conductor surface, and there is an effect that the conductivity of the conductor wiring is not impaired.

Further, if the conductor is formed by an electroplating method, it is possible to increase the precision, density and current capacity of the wiring. Moreover, depending on the plating conditions, conductor wiring having a mushroom-shaped cross section can be formed, so that the conductor can be prevented from dropping due to the shape effect, the current capacity can be increased by increasing the cross-sectional area, and the conductor surface can be cleaned by preventing resin from seeping out. There are various effects.

Further, when a photocurable resin is used as the insulating mask, a photolithography method can be used in the pattern forming step, so that a high-precision and high-density wiring pattern can be formed, and the step is simplified. This has the effect.

As described above, according to the present invention, a high-precision and high-density conductor wiring pattern in a concave portion of a molded article having a three-dimensional shape, which has high reliability and can achieve a large current capacity. Is easy to form, and since such a molded circuit body can be manufactured at a low cost, the present invention has an industrially extremely large effect.

[Brief description of the drawings]

FIG. 1 is a view showing a manufacturing process of a molded circuit body according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Temporary board 2 Insulating mask 3 Electric circuit 4 Conductor wiring 5 Lower mold 6 Upper mold 7 Cavity 8 Gate

Claims (8)

[Claims] 1. A conductive wiring pattern formed on a surface of an insulating substrate, wherein an insulating mask is provided on a surface of the insulating substrate in a space between the conductive wiring pattern and the surface thereof. A molded circuit body provided on the same surface. 2. The molded circuit body according to claim 1, wherein said insulating mask is made of a photocurable resin material. 3. The molded circuit body according to claim 1, wherein a base of the conductor wiring pattern is embedded in the insulating substrate. 4. The molded circuit body according to claim 1, wherein the conductor wiring pattern is formed of a metal layer formed by an electroplating method. 5. The molded circuit body according to claim 1, wherein said insulating substrate is made of a thermoplastic resin material. 6. A step of covering an area other than the conductive wiring pattern area on the surface of the temporary substrate having conductivity with an insulating mask, and a step of electroplating a conductive wiring pattern in a conductive wiring pattern area not covered by the insulating mask. Forming, and forming an insulating substrate on the surface on which the conductive wiring pattern is formed, and removing only the temporary substrate while leaving the conductive wiring pattern and the insulating mask on the insulating substrate,
A method for manufacturing a molded circuit body, comprising: 7. The method according to claim 6, wherein the insulating mask is made of a photocurable resin material. 8. The method according to claim 6, wherein the insulating substrate is made of a thermoplastic resin material.