JPH06238708A - Integrated printed circuit board molded form and its production - Google Patents

Abstract

PURPOSE:To provide a molded form in which a printed circuit board is accurately and strongly stuck to and followed by the three-dimensional faces of the resin molded form and multifunctionality of the circuit is made easy. CONSTITUTION:A prescribed circuit pattern is formed on the face of one side of a printed circuit board 1 and an adhesive layer is formed on the face of the other side. An integrated printed circuit board molded form is constituted by integrating the printed circuit board 1 with a resin molded form produced by injection molding through the adhesive layer. In the integrated printed circuit board molded body, a through-hole 3 is formed in the position wherein the printed circuit board is opposed to a resin injection gate 7 in a time for molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated type printed circuit board molded body and a method for manufacturing the same, and more particularly, the printed circuit board accurately and strongly adheres to and follows the three-dimensional surface of the resin molded body. TECHNICAL FIELD The present invention relates to an integrated printed circuit board molded body that is easily functionalized and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recently, audio, computer, 8
Electric products such as millivideos and mobile phones have advanced in performance, and along with this, there is an increasing need for miniaturization, weight reduction, and thinning. At the same time, electromagnetic noise generated from other electronic devices may cause the circuit to malfunction. Therefore, an electromagnetic wave shield that covers the entire printed circuit board and the entire circuit component is often provided. As the electromagnetic wave shield, generally, a metal plate such as an aluminum plate is provided inside the casing of the electronic device, or a resin in which conductive particles are kneaded is used to impart electromagnetic wave shielding property to the casing itself. Is being done.
However, such an electromagnetic wave shield method has a limit in reducing the thickness of electronic equipment. Therefore, a so-called integrated printed circuit board molded body has been proposed in which a printed circuit board is closely attached to the inner surface of the casing of an electronic device.

Japanese Unexamined Patent Publication (Kokai) No. 2-7592 discloses a metal vapor deposition layer and 0.5 to 35 μm on the surface of a plastic film.
The molded simultaneous integrated printed circuit board molded article is disclosed in which a printed circuit board on which a metal plating layer is provided and a predetermined circuit pattern is formed and molded simultaneously with a resin having a predetermined shape. In the integration method as described above, as shown in FIGS. 1 to 5, usually, a predetermined circuit pattern 2 is formed on one surface and the adhesive layer 4 is formed on the other surface.
Cavity formed by fixing the printed circuit board 1 made of a plastic film on which one side is formed is fixed to one surface of the injection molding die 5 by suction holes 10 and retaining pins or the like (not shown), and covering the other die 6. Molten resin is injected into the surface of the adhesive layer 4 of the printed circuit board 1 from the injection gate 7 to integrally form the printed circuit board 1 and the resin molded body 8.

[0004]

[Problems to be solved by the invention] However,
In the above conventional method, as shown in FIG. 3, the molten resin flow 9 injected from the injection gate 7 collides with the adhesive layer 4 of the printed circuit board 1 at a high flow rate and melts and softens the adhesive layer 4. , The adhesive is dispersed in all directions with the flow of resin,
As a result, there is a problem that the adhesive strength and the adhesiveness between the resin molded body 8 and the printed circuit board 1 are reduced in the integrated printed circuit board molded body as a product. Therefore, an object of the present invention is to provide an integrated printed circuit board molded body in which the printed circuit board closely and accurately adheres to and follows the three-dimensional surface of the resin molded body, and the circuit can be easily multifunctional. Is.

[0005]

The above object can be achieved by the present invention described below. That is, according to the present invention, a printed circuit board having a predetermined circuit pattern formed on one surface and an adhesive layer formed on the other surface is integrated with a resin molded body by injection molding through the adhesive layer. And a through-hole formed in the printed circuit board at a position facing the resin injection gate at the time of molding, and the manufacturing method thereof. Is the way.

[0006]

[Operation] When forming the integrated printed circuit board molded body,
By forming one or a plurality of through holes 3 in the printed circuit board 1 at a position facing the injection gate 7, the resin flow injected from the injection gate 7 is Since it collides with the surface of the mold 5 and consequently spreads in all directions with the flow velocity reduced, the action on the adhesive layer 4 formed on the printed circuit board 1 in the through hole is weak, and therefore the flow of the adhesive layer 4 is reduced. Provided is an integrated printed circuit board molded body which does not occur and has excellent adhesive strength and adhesion of the printed circuit board 1. Further, by providing the retaining pin of the printed circuit board 1 on the mold surface opposite to the through hole 3, the resin flow also collides with the top of the retaining pin, and the adhesive layer is formed in the same manner as above. No flow or deformation of 4.

[0007]

The present invention will now be described in more detail with reference to the preferred embodiments shown in the drawings. As shown in FIG. 4, the integrated printed circuit board molded body of the present invention has a predetermined circuit pattern 2 formed on one surface and an adhesive layer 4 formed on the other surface. It is integrated with a resin molding 8 formed by injection molding through a material layer 4, and a through hole 3 is formed at a position of the printed circuit board 1 facing the resin injection gate 7 at the time of molding. It is characterized by Although only one injection gate and one through hole are shown in the drawings, in actuality, a plurality of injection gates and through holes are often provided according to the shapes and sizes of the circuit board and the molded body.

The printed circuit board 1 itself used in the present invention is conventionally known, except that a through hole 3 is provided at an arbitrary position where the circuit pattern 2 is not formed, preferably corresponding to the injection gate 7. Any of the known printed circuit boards can be used in the present invention by providing the through holes 3 therein. The through holes 3 can be easily formed by punching the known printed circuit board 1 into a desired shape, for example, a circle, an ellipse, a triangle, a quadrangle, or the like.
The shape of the through hole is particularly preferably an elliptical shape, and the elliptic shape has an advantage that the retaining pin can be advanced and retracted with a margin compared to a circular shape.

The size of the through hole 3 is not particularly limited, but is preferably the same as or slightly larger than the diameter of the resin injection gate 7 formed in the mold of the injection molding machine described later. The size of the through hole 3 varies depending on the injection molding machine used, the size of the printed circuit board 1 and the integrated printed circuit board molded body to be formed, etc., but preferably the short diameter is 1.5 mm and the long diameter is about 4 mm. An ellipse or a circle having a diameter of about 1.0 to 5.0 mm is preferable.
The printed circuit board 1 itself may be a known flexible or rigid circuit board, for example, a flexible plastic film or a base material such as a rigid glass base epoxy resin-impregnated substrate or paper base phenolic resin-impregnated substrate, A circuit pattern 2 provided on one surface and an adhesive layer 4 provided on the other surface, and an insulating resin layer (not shown) is further formed on the surface of the circuit pattern 2 if necessary. Alternatively, an electromagnetic shield layer (not shown) such as a copper layer may be provided between the adhesive layer 4 and the substrate.

For example, the film used for the flexible printed circuit board 1 is not particularly limited, but since the electronic parts are welded with solder or the like, it has heat resistance, and further has flexibility and flexibility. Those having excellent flexibility are preferable, for example, polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyether sulfone, polyether ether ketone, aromatic polyamide, polyarylate, polyimide, polyamideimide, polyetherimide, Films such as polyphenylene sulfide (PPS) and their halogen group- or methyl group-substituted products can be used. Of these, the polyimide film is particularly preferable. The thickness of these films is usually about 12 to 300 μm, preferably about 25 to 80 μm.

For example, the circuit pattern 2 provided on the polyimide film substrate is formed by forming a conductive metal layer on the substrate using a conductive material such as copper or aluminum and etching it by a photoresist method or the like. It can be formed by a conventional method such as a subtractive method for forming a substrate or an additive method for forming a circuit on a substrate by electroless plating or electrolytic plating. The metal layer can be formed of a metal such as copper or aluminum as a thin film layer on the substrate by a vacuum deposition method, a sputtering method, or an ion plating method. or,
The circuit can also be formed by a screen printing method using a conductive ink. Further, a copper surface may be formed by adhering a copper film, and the copper surface may be used to form a circuit.

The metal layer on the back surface can be used as an electromagnetic wave shield layer as a whole, but can also be used as a ground electrode together with it. In this case, though the through hole is provided in the substrate in advance, the through hole 3 can also be used as the through hole in the present invention. If the metal layers on both surfaces are made to communicate with each other through the through hole and the circuit pattern 2 is formed on one side in this state, the metal layer can be connected to the ground through the through hole at a predetermined position. It is also possible to form a multi-layer circuit by allowing the metal layers on both sides to communicate with each other through the through holes. When mounting an electronic component such as an IC on the circuit pattern 2, first, the entire circuit pattern 2 is made of polyester,
An insulating layer made of a resin such as polyacrylic or polyurethane is formed by silk screen printing or the like, and then an opening is made at a predetermined position of the insulating layer by a photoresist method to expose the circuit pattern 2 and pre-or parts. Solder is attached to the opening before mounting, and electronic parts are soldered to that portion. When an electromagnetic wave shield layer is provided, it is preferably composed of a metal vapor deposition layer + metal plating layer. The metal vapor deposition layer and the metal plating layer may be the same as those described above.

In the present invention, the printed circuit board 1
A mark for forming the circuit pattern 2, a mark for setting a mold, a mark for mounting, and the like can be appropriately provided on the.
The above-mentioned various marks may be separate, or one kind may also serve as a plurality of kinds of marks, but the formation thereof may be performed before the formation of the circuit pattern 2, simultaneously, or simultaneously with the circuit pattern 2 (or the insulating property). It may be provided by printing after forming the resin layer). If such a mark is provided, the circuit pattern 2 can be obtained by using the image identification device.
Can be printed without error, mounting of a printed circuit board film on a mold, mounting of electronic components, and the like. This is effective for accurate positioning of component mounting because the printed circuit board attached to the inner surface of the housing molded body is not flat. In particular, the mold set mark is designed to correct the deviation of the printed circuit board 1 due to the injection of the resin, etc., according to the resin used, the injection pressure, etc.
Is preferable because it can be set in a mold.

Further, the adhesive layer 4 provided on the surface opposite to the circuit pattern 2 and the film or rigid base material is capable of following the film or rigid base material to the resin 8 serving as the casing base material during injection molding. It is a layer that is well adhered and is appropriately set according to the casing base material (or the metal for the electromagnetic wave shielding layer) and the film or rigid base material. For example, when polyamide is used as the resin for the casing base material and polyimide is used as the film, an epoxy adhesive may be used, and as the resin for the casing base material, acrylonitrile-butanediene-styrene copolymer is used. When a polyester (ABS resin) film is used as the film, a polyester adhesive may be used. When the adhesive layer 4 is provided on the back surface of the exposed portion of the printed circuit board, the adhesive layer 4 is
The same as the above may be used.

The thickness of the adhesive layer 4 as described above is 5 μm or more, preferably about 5 to 15 μm. Thickness is 5 μm
If it is less than 1, the adhesive strength is weak, the circuit board and the injection resin are not sufficiently adhered, and the circuit board may float.
If it exceeds μm, the adhesive may flow due to the injection pressure at the time of injection of the resin, and the adhesive may stick out from the substrate surface and adhere to the circuit surface, which may result in defective conductivity of the circuit. Elongation rate of the printed circuit board 1 composed of such layers (measured by Tensilon)
Is preferably 5% or more, particularly preferably 5 to 30%. If the elongation is less than 5%, the metal layer may not be able to completely follow the three-dimensional shape in the later-described injection molding, and the metal layer is likely to be ruptured. If it exceeds 30%, the dimensional stability is significantly deteriorated. However, it is not preferable because an erroneous operation tends to occur when electronic components are automatically mounted.

Next, a method for manufacturing an integrated type printed circuit board molded body obtained by integrally molding this printed circuit board with resin will be described. According to the manufacturing method of the present invention, as shown in FIGS. 1, 2 and 4, a circuit of a printed circuit board 1 in which a predetermined circuit pattern 2 is formed on one surface and an adhesive layer 4 is formed on the other surface. The pattern 2 surface is fixed to one mold (male) 5 surface of injection molding, and combined with another mold (female mold) 6 having one or a plurality of injection gates 7, the injection gate 7
A position facing the injection gate 7 of the printed circuit board 1 when the printed circuit board 1 is integrally formed with the resin molded body 8 having a predetermined shape via the adhesive layer 4 by injecting molten resin from One or a plurality of through holes 3 are formed in the above.

The resin for injection molding is not particularly limited as long as it can be injection-molded, but a resin having a certain degree of heat resistance for soldering electronic parts is preferable. Polyamide, polyether Various polymer alloys such as imide, polycarbonate, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyphenylene sulfide (PPS), and fluororesin can be used. Among these, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyphenylene sulfide (PPS), 4-6
Polyamide such as nylon and modified polyamide 6T is preferable. The molding method itself may be based on a conventionally known method.

In FIG. 1, the injection mold is a male mold 5.
And a female die 6, and when the male die 5 and the female die 6 are closed, a cavity 8 is formed. The male mold 5 has a surface that is processed to be slippery (Teflox processing or the like), and various three-dimensional surfaces are formed according to the inner wall surface of the integrated printed circuit board molded body. At the exposed parts of the printed circuit board, the mold fits perfectly. Further, one or a plurality of suction ports 10 for sucking and fixing the printed circuit board may be provided in the male die 5, and the flat end of the male die 5 is not shown, Through hole 3 provided in printed circuit board 1
There may be a retaining pin inserted into the. When the retaining pin can advance and retreat in the through hole, the retaining pin is retracted in accordance with the closing of the male die 5 and the female die 6 or the injection of the resin, so that the resin is also retained in the through hole of the circuit board. Is filled. Even when the retaining pin is used, the retaining pin does not completely retreat when the resin is injected, and the retaining pin has a thickness of 0.2 to 0.5.
It is also possible to mold while leaving mm. If the retaining pin is left in this way, the resin pressure during resin injection will
It is possible to prevent the injection resin from backing from the through hole 3 to the surface of the printed circuit board 1. FIG. 4 shows a cross section of a product using a retaining pin that partially retracts. Reference numeral 11 in the figure is a recessed portion of the mark of the retaining pin. On the other hand, the female mold 6 has an injection gate 7
However, the number of injection gates 7 is not limited to one as shown in the figure, and a plurality of injection gates 7 may be provided depending on the shape and size of a desired molded product. In this case, it is preferable that the number and positions of the through holes correspond to the number and positions of the gates. The male die 5 is movable in the left-right direction in the figure with respect to the female die 6.

When the printed circuit board 1 is fixed to a predetermined position of the male die 5 as described above, the die is closed and a desired molten resin is injected from one or a plurality of injection gates 7. The molten resin injected from the above passes through one or a plurality of through holes 3 provided in the printed circuit board 1 and collides with the surface of the male die 5. Due to this collision, the flow of the molten resin becomes gentle and spreads in all directions to fill the entire cavity. After the filling, the mold is cooled to an appropriate temperature and then the mold is opened to obtain a desired integrated printed circuit board molded body. In this case, if the through hole 3 is not formed in the printed circuit board 1, as shown in FIG.
As shown in FIG. 5, the molten resin injected from the gate 7 directly collides with the adhesive layer 4, melts the adhesive and is washed away in four directions, and a step is generated in the adhesive layer 4 and the molten resin adheres in a region where the molten resin collides. The amount of the agent is reduced, and finally, an integrated printed circuit board molded body having insufficient adhesive strength and adhesion between the resin molded body and the printed circuit board 1 is obtained. On the other hand, in the present invention, as described above, the flow of the adhesive is small, and an integrated printed circuit board molded body excellent in adhesive strength and adhesiveness can be obtained.

The printed circuit board 1 may be installed on the male mold 5 by using the one or a plurality of through holes 3 as a mold installation mark and using an optical device as described above. , Can be done accurately. Further, in order to make the printed circuit board 1 more sufficiently follow the three-dimensional shape, it is preferable to preform the printed circuit board 1 in advance according to the male shape. The preforming is vacuum forming,
It may be carried out by a molding method such as thick air molding. Alternatively, it may be heat-molded after being placed on the male mold described above.

[0021]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. Example 1 After performing plasma treatment on both sides of a polyimide film (thickness: 20 μm), a copper vapor deposition layer (thickness: about 500 Å) was provided by a sputtering device, and a copper plating layer (thickness: 8) was provided on top of this.
μm) was formed. Next, the circuit pattern 2 and the like were provided on one surface by a photoresist method. A polyester resin layer (insulating resin layer) was entirely formed on the circuit pattern 2, a hole was formed by a photoresist method so that the circuit was exposed at a predetermined position, and a solder was filled therein. The elongation of this printed circuit board measured by Tensilon was 10%.

The printed circuit board 1 thus obtained
After forming an epoxy resin layer (adhesive resin layer) having a thickness of 7 μm on the back surface of the substrate 1, a through hole 3 having a diameter of 2.0 mm was provided by punching at a position where the circuit pattern 2 was not present substantially in the center of the substrate 1. After that, this circuit board is placed on the male die 5, and the through hole 3 is a female die injection gate 7 (gate diameter 1.0 mm).
Position so that it will come to the front of
The modified polyamide 6T (Aren A315, manufactured by Mitsui Petrochemical Co., Ltd.) was injection-molded at the temperature of, and cooled to obtain an integrated printed circuit board molded body of the present invention. Comparative Example 1 An integrated printed circuit board molded body of Comparative Example was obtained in the same manner as in Example 1 except that the through hole 3 was not provided.

The molded products produced as described above are heat-treated at 120 ° C. for 3 hours to cure the epoxy resin layer, and then environmental tests are carried out on the molded products of Examples and Comparative Examples. The adhesiveness was evaluated by. In the cross-cut test, a single-blade razor cutting blade is held at about 30 ° C against the effective surface of the sample to reach the substrate 1 mm or 2 m.
100 squares (10 × 10) of m squares were prepared, and the cellophane adhesive tape was completely adhered to the surface, and one end of the tape was immediately kept at a right angle to the coating surface, and was instantaneously peeled off.
The effective surface is 20 mm × centered on the through hole 3 of the molded substrate.
It is 20 mm square. The results are shown in Table 1 below. still,
The initial condition is after heat treatment.

[0028]

[Table 1] Environmental test conditions Heat cycle test; 80 ° C 1 hour ← → -30 ° C 1 hour 10 cycles. Constant temperature and humidity test; 60 ° C 90% R.C. H. 240 ° C heat resistance test; 90 ° C for 192 hours Cross- cut test evaluation score 10: Each cut is fine and both sides are smooth, and there is no peeling at each intersection of cuts and each square. 8: There was a slight peeling at the intersection of cuts, and there was no peeling at every square, and the area of the defect was 5% of the total square area.
As is clear from the above table, in the examples having the through holes of the present invention, the adhesiveness was good in the initial adhesion and the environmental test, as compared with the comparative example having no through holes.

[0029]

According to the present invention, one or a plurality of through holes 3 are formed in the printed circuit board 1 at a position facing the injection gate 7 when forming the integrated type printed circuit board molded body.
By forming the above, the resin flow injected from the injection gate 7 collides with the other mold surface in the through hole, and as a result, the resin flow spreads in all directions in a state where the flow velocity is reduced. The action on the formed adhesive layer 4 is weak, so that the flow of the adhesive layer 4 does not occur and the printed circuit board 1
Provided is an integrated printed circuit board molded body having excellent adhesion. Also, on the mold surface at the position corresponding to the through hole 3,
By providing the retaining pins of the printed circuit board 1, the resin flow also collides with the tops of the retaining pins, so that the adhesive layer 4 does not flow or deform as in the above case.

[0030]

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method for manufacturing an integrated printed circuit board molded body according to the present invention.

FIG. 2 is a diagram illustrating a method for manufacturing an integrated printed circuit board molded body according to the present invention.

FIG. 3 is a diagram illustrating a conventional method for manufacturing an integrated printed circuit board molded body.

FIG. 4 is a diagram illustrating a cross section of an integrated printed circuit board molded body of the present invention.

FIG. 5 is a diagram illustrating a printed circuit board used in the present invention.

[Explanation of Codes] 1: Printed circuit board 2: Circuit pattern 3: Through hole 4: Adhesive layer 5: Male mold 6: Female mold 7: Injection gate 8: Resin molding (cavity) 9: Resin flow 10: Suction Mouth 11: Recessed pin mark recess

Claims (3)

[Claims] 1. A printed circuit board having a predetermined circuit pattern formed on one surface and an adhesive layer formed on the other surface is integrated with a resin molded body by injection molding through the adhesive layer. In the integrated printed circuit board molded body,
An integrated printed circuit board molded body, wherein a through hole is formed in the printed circuit board at a position facing the resin injection gate at the time of molding. 2. A circuit surface of a printed circuit board having a predetermined circuit pattern formed on one surface and an adhesive layer formed on the other surface is fixed to one mold surface of an injection molding machine, and an injection gate is provided. Of an integrated type printed circuit board molded body in which a molten resin is injected from an injection gate to form the printed circuit board integrally with a resin molded body of a predetermined shape through an adhesive layer in combination with another mold having In the manufacturing method, a through hole is formed at a position of the printed circuit board facing the injection gate, and a method for manufacturing an integrated printed circuit board molded body. 3. The method for manufacturing an integrated printed circuit board molded body according to claim 2, wherein the through hole is used as a retaining pin or a positioning member for the printed circuit board.