JP4830881B2 - Circuit board for molding and three-dimensional circuit board obtained by molding the same - Google Patents

Description

  The present invention relates to a molding circuit board and a three-dimensional circuit board obtained by molding the molding circuit board.

  Planar film circuit boards such as film antennas are used in small electronic devices such as mobile phones because of their high flexibility and miniaturization. Recently, there has been a demand for further downsizing, multi-functionalization, and cost reduction of such electronic devices, and a method for mounting a three-dimensional circuit board on an electronic device has been proposed and realized. Yes.

  As the three-dimensional circuit board, there is a molded printed circuit board (MPCB) or an injection molded circuit component (MID: Molded Interconnection Device). These have obtained the three-dimensional circuit board by the injection molding method, but if the manufacturing method is divided roughly, there are a plating method and a circuit film method.

  In the plating method, a circuit board is obtained by plating a resin molded body having a desired three-dimensional shape. Typical production methods include a one-shot mold method and a two-shot mold method.

  In the one-shot mold method, first, a resin capable of electroless plating is used, the resin is molded into a desired three-dimensional shape, and then a photoresist is applied to the surface of the obtained resin molded body, and then a circuit pattern is formed. Is exposed and developed, and finally, the surface of the exposed resin molded body is subjected to electroless plating to produce a three-dimensionally formed circuit board.

  In contrast, in the two-shot mold method, a resin mixed with a catalyst for plating is used, the resin is molded into a desired three-dimensional shape by the first injection molding, and further obtained by the second injection molding. A surface layer that is not subjected to electroless plating is formed on a predetermined portion of the surface of the resin molded body, and then a portion that is not formed with the surface layer of the resin molded body is subjected to electroless plating to form a conductive portion. To do.

  On the other hand, with the circuit film method, a predetermined circuit pattern is formed on the film surface, and when molding a resin molded body having a desired three-dimensional shape, the circuit pattern is integrated with the resin molded body or transferred to the resin molded body. There is an in-mold method. In the in-mold method, a predetermined circuit pattern is formed on a film surface of a substrate by a known method, and then the substrate on which the circuit pattern is formed is loaded into a molding die and filled with resin. The circuit pattern on the film surface of the base material is integrated with the resin molding or transferred to the resin molding to obtain a three-dimensional circuit board.

  However, these manufacturing methods have the following problems due to their characteristic manufacturing processes.

  For example, in the one-shot mold method, the line width of the circuit pattern can be reduced to about 100 μm and a high-density circuit pattern can be obtained, but the manufacturing process is very long and the cost is high. Moreover, it is unsuitable for manufacturing a three-dimensional circuit board having a three-dimensional curved surface shape. Furthermore, the resin material is limited, and circuit patterning is difficult.

  In addition, although the two-shot mold method is suitable for manufacturing a three-dimensional circuit board having a three-dimensional curved surface shape, a high-precision molding die is required or two injection moldings are performed. As a result, costs increase. In addition, it is difficult to reduce the line width of the circuit pattern to less than 500 μm, and the circuit pattern cannot be densified.

  On the other hand, in the circuit film type in-mold method, various methods can be applied to the formation of the circuit pattern, the degree of freedom in selecting the resin material is high, and the line width of the circuit pattern can be reduced. Thus, a high-density circuit pattern can be obtained. However, it is not fully satisfactory in terms of the degree of adhesion between the circuit pattern and the resin molded body and the ability to follow a three-dimensional shape.

  In order to eliminate the disadvantages of these production methods, Patent Document 1 discloses the surface of a spherical molded body formed of a forming material having a melting point lower than the thermal decomposition temperature of the thermosetting resin and higher than the molding temperature. A predetermined conductor circuit pattern is formed, and the spherical molded body is disposed in the mold while maintaining a predetermined space with the inner peripheral surface of the mold, and the space is filled with a thermosetting resin. The thermosetting resin is thermoset at the molding temperature to form a thermosetting resin molding, and then the spherical molding is melted and removed from the thermosetting resin molding to produce a three-dimensional circuit board. It is described.

  However, in any of the manufacturing methods using these injection molding methods, the problems caused by the injection molding method itself that a long process, an expensive metal mold, and a thin molded body are difficult to obtain are not solved. . In addition, the line width of the circuit pattern is limited to about 100 μm, which is not necessarily sufficient to increase the density of the circuit pattern. Furthermore, when obtaining a resin molded body capable of electroless plating, there is a problem in that a large amount of expensive Pd must be added to the resin for producing the resin molded body and kneaded.

  On the other hand, Patent Document 2 discloses a film form in which a conductive part is formed of copper or silver on the surface of a resin film or a resin sheet made of an amorphous polymer such as ABS resin, polycarbonate, polyethersulfone or the like. A member and a resin film made of an amorphous polymer such as ABS resin, polycarbonate, polyethersulfone, and the like are arranged so that the conductive portion is sandwiched, and the film-like member is formed by blow molding or vacuum molding. A manufacturing method is described in which a resin film is brought into close contact and molded into a three-dimensional shape to obtain a three-dimensional circuit board.

  In such a manufacturing method, since the circuit pattern is formed in advance on the surface of the resin film or resin sheet by the photoresist method or the like, it is easy to increase the density of the circuit pattern. However, in the subsequent three-dimensional molding process, if the three-dimensional molding in two or more directions is performed on the resin film or resin sheet having the circuit pattern by drawing or the like, the elongation rate or tension between the metal of the circuit pattern and the resin Due to the difference in strength, there arises a problem that the wiring constituting the circuit pattern is broken.

In order to eliminate such problems, a part of the resin film or the like is cut so that the desired three-dimensional shape is obtained, and the elongation of the metal and the resin is within a range that can be traced to each other. It is necessary to perform processing. However, there is a problem that a wiring cannot be formed in a cut portion such as a resin film, which is a great restriction in circuit design.
JP 09-148712 A Japanese Patent Application Laid-Open No. 04-08292

  An object of the present invention is to provide a circuit board for molding processing that does not damage a circuit pattern even when three-dimensional molding in two or more directions is performed by drawing or the like, and a three-dimensional circuit board obtained by molding the circuit board.

The circuit board for molding processing according to the present invention has a first layer made of a resin film , which is selected from polyimide, polyetherimide, polyethylene terephthalate, and polyethylene naphthalate, and has a thickness of 10 to 250 μm, and a desired pattern. a second layer of circuitry, polyimide, polyetherimide, polyethylene terephthalate, resin film or a polyester selected from polyethylene naphthalate, polyimide, epoxy, Ri Do from the resin layer formed of the resin coating material is selected from acrylic A third layer made of a resin layer having a thickness of 2 to 100 μm is laminated, and the adhesion strength between the first layer and the second layer is 390 N / m or more.

  The first layer and the third layer are preferably made of any one of polyimide, polyetherimide, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN).

In the present invention, the second layer is formed directly on the surface of the first layer . For this reason , Ni, Cr, Co, Mo, W, or these are mainly used between the first layer and the second layer. A seed layer made of an alloy thin film selected from alloys as components is formed. The seed layer preferably has a thickness of 50 to 1500 mm.

Or it is preferable that the primer coat which is 0.1-20 micrometers in thickness is given to the surface of the said 1st layer. When the primer coat is applied to the surface of the first layer, the thickness of the seed layer is particularly preferably 0.1 to 20 mm.

  Note that the present invention is preferably applied to a circuit board for molding processing in which the second layer is made of copper.

  By using the circuit board for molding processing according to the present invention to form a three-dimensional shape, a three-dimensional circuit board having no damage to the circuit pattern can be obtained.

  The molding circuit board according to the present invention has a high adhesion strength of 390 N / m or more between the first layer of the resin film and the second layer of the wiring, and therefore can be easily subjected to pressing or drawing, and Since a three-dimensional circuit board with no damage to the circuit pattern can be manufactured, it can contribute to downsizing, multi-functionalization, and cost reduction of electronic devices.

  In the present invention, the adhesion strength between the first layer and the second layer needs to be 390 N / m or more. Therefore, if the adhesion strength between the first layer and the second layer can be increased to 390 N / m or more, the second layer of the metal foil is bonded to the first layer of the resin film via an adhesive, and the second layer of the metal foil is processed. Then, a circuit board for molding may be manufactured by forming a resin layer as a third layer on the second layer of the circuit, and then forming the second layer of the circuit. In the method, the second layer may be provided by a plating method on the surface of the first layer of the resin film so that the adhesion strength is 390 N / m or more.

  However, when forming a circuit composed of wiring with a width of 100 μm or less, it is recommended that a metal layer be provided directly on the first layer of the resin film from the viewpoint of the reliability of the obtained circuit and electrical characteristics. The

  In order to improve the close contact between the first layer of the resin film and the second layer of the metal, the molding circuit board according to the present invention is provided with the second layer of the metal, the third layer of the resin film and the third layer of the resin layer. By adopting a three-layer structure so as to be sandwiched between the layers, it is possible to apply a stress to the second metal layer uniformly and to perform a three-dimensional molding without breaking the second metal layer.

Examples of the resin film that can be used as the first layer include polyimide, polyetherimide, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). The reason why these are selected is because, for example, transparency, insulation, heat resistance, corrosion resistance, and the like required when an antenna is formed from a three-dimensional circuit board are improved. However, these resins can also be used for other applications that are employed in circuit boards such as switch boards and keyless entry boards.

  The thickness of the first layer is determined by the strength of the film, processability during three-dimensional molding, and other uses of the three-dimensional circuit board, but is preferably 10 to 250 μm.

  The material that can be used as the second layer of the circuit is not particularly limited as long as it has a function as an antenna, and from that viewpoint, any conductive material may be used. However, from the viewpoint of electrical characteristics and ease of circuit formation, copper may be used. Alternatively, an alloy containing phosphorus, silver, tin, or the like and containing copper as a main component is preferable.

  The thickness of the second layer is determined depending on the use of the three-dimensional circuit board, but is preferably 1 to 50 μm.

  In addition, when the second layer is directly formed on the first layer, Ni, Cr, Co, and the like are used as seed layers in order to ensure adhesion strength between the first layer of the resin film and the second layer of the circuit. It is preferable to provide a thin film of Mo, W, or an alloy containing these as a main component on the first layer. Further, it is preferable to provide a discoloration preventing film on the surface of the second layer of the circuit facing the third layer from the viewpoint of preventing discoloration due to long-term use of the antenna.

The thickness of the seed layer, adhesion, cost aspects, further, also the design of the applications of the three-dimensional shaping circuit is determined by considering the case of providing alone, and 50 to 1500 Å, the primer coat When applied to the surface of the first layer, the thickness is preferably 0.1 to 20 mm.

  Further, depending on the type of the resin film, it is preferable to apply a primer coat to the surface of the first layer as necessary. The primer coat is formed of at least one of acrylic resin, urethane resin, and polyester resin. When an acrylic resin is used, the acrylic resin is at least one of a thermosetting acrylic resin or a thermoplastic acrylic resin, or a mixture thereof. When a urethane resin is used, a polyester type or a polyether type is used. In the case of using a polyester resin, at least one of unsaturated polyester and saturated polyester, or a mixture thereof is preferable. It is preferable to use these resins because they have strong adhesion strength and high transparency.

  The thickness of the primer coat is preferably 0.1 μm or more from the viewpoint of developing uniform and strong adhesion strength. On the other hand, if it exceeds 20 μm, the smoothness of the surface is deteriorated, the copper of the second layer cannot be formed uniformly, and the difference in bending characteristics with the material of the first layer is increased, resulting in uneven stress. This is not preferable because it may break in the middle.

  The formation of the seed layer and the formation of the primer coat may be performed selectively or in combination.

The resin that can be used as the resin layer of the third layer is not particularly limited as long as it is a resin that can be molded by a mold during molding into a three-dimensional shape, but when it is molded by applying heat during molding In addition, since it must be stretched in the same manner as the first layer of the resin film, it is preferable to use the same material as that of the first layer or a material whose glass transition temperature and tensile properties are close to those of the first layer. For the third layer of the resin layer, a film of polyimide, polyetherimide, polyethylene terephthalate (PET), polyethylene naphthalate (PEN) or a resin coating material of polyester, polyimide, epoxy, or acrylic can be used. In particular, if the adhesion strength between the first layer and the second layer is 390 N / m or more, the material of the third layer may be any of the above .

  The thickness of the third layer is also determined by the strength of the film or resin, processability during three-dimensional molding, and other uses of the three-dimensional circuit board, but is preferably 2 to 100 μm.

  Next, the manufacturing method of one Example of the circuit board for shaping | molding processing of this invention is demonstrated. The circuit board for molding according to the present invention can be manufactured, for example, by the following steps.

(1) A primer coat treatment is performed on the surface of the first layer of the resin film.

  The primer coating treatment may be a treatment that is usually performed, and may be performed by uniformly applying a resin using a roll coater method, a spin coating method, or the like, and then drying it.

(2) A seed layer is provided on the obtained primer coat by vapor deposition or sputtering.

  The conditions of the vapor deposition method and sputtering method specifically employed are not particularly limited, and may be appropriately selected from the already performed conditions according to the metal used as the target.

(3) A conductive layer is further provided on the obtained seed layer by at least one of vapor deposition, sputtering, and plating.

  The material of the conductive layer is preferably copper from the viewpoint of ease of processing and the electrical characteristics of the wiring portion. The specific conditions of the vapor deposition method, the sputtering method, or the plating method may be appropriately selected from the already performed conditions as described above.

(4) A desired circuit is formed by patterning the obtained conductive layer and seed layer.

  For example, a photoresist is screen-printed on the surface of the conductive layer, or a photoresist film is bonded, and an etching mask is formed by exposing and developing using a mask having a desired pattern, and etching obtained. The conductor layer and the seed layer are etched using the mask. For such a method, a technique used for manufacturing a printed wiring board, which is an electronic component, can be applied as it is.

(5) A third layer of a resin film or a resin coating material is provided so as to sandwich the circuit with the first layer of the resin film.

  After the circuit is formed, a liquid resin coating material is applied to the surface side of the circuit and dried, or a film-like resin is applied to form the third layer.

  Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a molding circuit board according to the present invention.

Example 1
As the first layer (1), a 38 μm thick PET resin film (Lumirror, manufactured by Toray Industries, Inc.) was used, and an acrylic resin (Fujikura Kasei Co., Ltd., ET5402) was uniformly applied to the surface at a thickness of 1 μm. The primer coat was applied by applying and drying. Next, a 1500-thick seed layer made of a Ni—Cr alloy was formed by vapor deposition. Then, the 10-micrometer-thick copper layer (2) was formed with the vapor deposition method, and the base material was obtained.

  The base material is subjected to a photo-etching method so that the copper layer (2) has a strip shape with a line width of 1 mm, and the obtained member conforms to JIS C6471 which is a method of pulling up the copper layer (2) vertically. Then, a tensile test was performed to measure the adhesion strength of the copper layer. A universal bond tester (manufactured by Daisy, series 4000) was used to measure the adhesion strength. The obtained results are shown in Table 1.

  After obtaining the base material in the same manner as described above, a resist film is attached to the copper layer (2) side, photoetching is performed, and a circuit pattern having a line width of 1 mm and electrodes on both ends of the circuit pattern are provided. Obtained. Thereafter, as a third layer (3), a resin film made of PET having a thickness of 38 μm was stuck with an adhesive to obtain a circuit board for molding.

  A dumbbell-shaped test piece (4) was prepared by a die cutting method and a tensile test was performed using the obtained circuit board for molding as shown in the plan view of FIG. The shape of the test piece (4) conformed to the standard of Z220 13B of JIS standard. In the tensile test, a constant current of 0.1 A of the sample was passed through the wiring (4b) from the electrodes (4a) at both ends while pulling up to 10% elongation, and the change in voltage between the electrodes (4a) was measured. This was done by checking whether or not the wiring (4b) was broken depending on the presence or absence of conduction. Table 1 shows the results obtained in the tensile test. The result of the tensile test is indicated by “X” when the fracture occurs, and by “◯” when the fracture does not occur. For the measurement, an autograph (manufactured by Shimadzu Corporation, AGS-J500N) was used. Tensile strength was set to “x” when a tensile test was performed for 5 samples at each speed under conditions of 5, 10 and 20 mm / min, and even one sample was confirmed to be broken at an elongation of 10%.

(Examples 2 to 6)
Except for changing the material of the first layer and the third layer and the processing to the first layer as shown in Table 1, in the same manner as in Example 1, obtaining the circuit board for molding, Evaluation was performed. The results are shown in Table 1. In addition, about Example 2, primer coating was performed similarly to Example 1, but about Example 3-6, only the seed layer was formed and primer coating was not performed.

(Comparative Examples 1 and 2)
A circuit board for molding processing in the same manner as in Example 1 except that the materials of the first layer and the third layer were changed as shown in Table 1 and the processing for the first layer was not performed. Each was evaluated. The results are shown in Table 1.

  From Table 1, it can be confirmed that sufficient processing performance can be obtained by setting the adhesion strength between the first layer and the second layer to 390 N / m or more regardless of the types of the first layer and the third layer. . Therefore, it is understood that a three-dimensional circuit board in which the circuit pattern is not damaged even if three-dimensional molding in two or more directions is performed by molding using the molding circuit board of the embodiment.

It is sectional drawing which shows one Example of the circuit board for a shaping | molding process of this invention. It is a top view which shows the dumbbell-shaped test piece used for the tension test.

Explanation of symbols

1 1st layer 2 2nd layer 3 3rd layer 4 Test piece 4a Electrode 4b Wiring

Claims (6)

A first layer made of a resin film selected from polyimide, polyetherimide, polyethylene terephthalate, polyethylene naphthalate and having a thickness of 10 to 250 μm, a second layer made of a circuit having a desired pattern, polyimide, poly polyetherimides, Ri Do polyethylene terephthalate, a resin film or a polyester selected from polyethylene naphthalate, polyimide, epoxy, resin layer composed of a resin coating material is selected from acrylic and a thickness of 2 to 100 m, the Three layers are laminated, and the first layer and the second layer are made of an alloy thin film selected from Ni, Cr, Co, Mo, W, or an alloy containing these as a main component. a 0.1～1500A, seed layer is formed, the adhesion between the first layer and the second layer Molding circuit board, wherein the degree is 390 N / m or more. 2. The circuit board for molding according to claim 1, wherein the surface of the first layer is coated with a primer coat having a thickness of 0.1 to 20 μm selected from an acrylic resin, a urethane resin, and a polyester resin .   The circuit board for molding according to claim 1 or 2, wherein the seed layer has a thickness of 50 to 1500 mm.   The circuit board for molding according to claim 2, wherein the seed layer has a thickness of 0.1 to 20 mm. The circuit board for molding according to any one of claims 1 to 4 , wherein the second layer is made of copper. A three-dimensional circuit board obtained by molding the circuit board for molding described in any one of claims 1 to 5 .

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