JP2008098370A - Wiring pattern forming method, wiring substrate, and electronic equipment using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further surely prevent short circuit caused by migration. <P>SOLUTION: A groove 12 is provided to a wiring pattern formation position of a surface of an insulating base material 11. A conductor layer 13 is formed by applying a conductive member to a bottom part of the groove 12. A sealing member with humidity resistance is applied to the groove 12 wherein the conductor layer 13 is formed, and a protection layer 14 is formed not to project from the surface of the insulating base material 11. Since the conductor layer 13 is formed in the bottom part of the groove 12, a creeping distance between conductor layers is elongated, and since the protection layer 14 is also provided, short circuit between the conductor layers 13 due to migration is prevented. Furthermore, since the protection layer 14 is formed not to project from the surface of the insulating base material 11, the protection layer 14 is hardly damaged when compared to the case that it is formed to project, thus further surely preventing short circuit between the conductor layers 13 due to migration. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wiring pattern forming method, a wiring board, and an electronic apparatus using the same. Specifically, by forming a conductor layer in the groove provided in the insulating base material and further forming a protective layer so as not to protrude from the surface of the insulating base material, a short circuit between the conductor layers due to migration is prevented. It is.

  In recent years, with the miniaturization of semiconductor integrated circuits, chip parts, etc., high-density mounting has been attempted. In addition, with the progress of high-density mounting, the wiring pattern is becoming finer. Thus, if the wiring pattern is made finer, the problem of ion migration is likely to occur. Ion migration is a phenomenon in which moisture generated by moisture absorption etc. adheres to the metal constituting the pattern, and when a voltage is applied to the conductor metal with this moisture attached, the potential difference is repeated by repeating dissolution, migration, and precipitation. A metal circuit is formed in the direction of the generated pattern. For this reason, when miniaturization of the wiring pattern is attempted, a short circuit between the patterns is likely to occur due to ion migration (hereinafter simply referred to as “migration”).

  For this reason, in the invention of Patent Document 1, a short circuit due to migration is prevented by covering a wiring conductor with a protective layer containing a fluororesin filler in an epoxy resin. Further, in the invention of Patent Document 2, a short circuit due to migration is prevented by providing a water repellent layer between adjacent electrodes and applying an insulating resin on the water repellent layer.

Japanese Patent Laid-Open No. 2001-210937 JP 2003-224349 A

  By the way, when providing a protective layer containing a fluororesin filler in an epoxy resin, the relative dielectric constant of the protective layer increases when the content of the fluororesin filler decreases, and when the content of the fluororesin filler increases, As a result, irregularities corresponding to the outer shape of the film are generated, and moisture in the atmosphere easily enters. For this reason, the content rate of the fluororesin filler must be appropriately managed so that the signal flowing in the wiring pattern is not adversely affected and the intrusion of moisture can be prevented.

  Further, when a protective layer is provided or when a water-repellent layer is provided and an insulating resin is applied, the protective layer or the insulating resin protrudes from the substrate surface. For this reason, the protective layer and the insulating resin come into contact with other substrates and parts, and the protective layer and the insulating resin are easily damaged. If the protective layer and the insulating resin are damaged, a short circuit due to migration may be prevented. It becomes impossible.

  Accordingly, the present invention provides a wiring board that can more reliably prevent a short circuit due to migration and an electronic device using the wiring board.

  The concept of the present invention is to increase the edge distance between conductor layers and prevent damage to the protective layer covering the conductor layer, thereby more reliably preventing a short circuit due to migration.

  In the present invention, a groove is provided at a wiring pattern forming position on the surface of the insulating base material, and a conductor layer is formed at the bottom of the groove. Moreover, a protective layer is formed in the groove in which the conductor layer is formed so as not to protrude from the surface of the insulating substrate.

  In the present invention, for example, a synthetic resin is used as the insulating base material. Here, when an insulating base material having a desired shape is formed by molding, a groove is simultaneously provided at a wiring pattern forming position on the surface of the insulating base material. A conductor layer is formed on the bottom of the groove by applying a conductive member using a dispenser, for example. Moreover, a sealing member is apply | coated on a conductor layer and a protective layer is formed so that it may not protrude from the surface of an insulating base material.

  According to the present invention, the groove is provided at the wiring pattern forming position on the surface of the insulating substrate, and the conductor layer is formed at the bottom of the groove. Furthermore, a protective layer is formed in the groove in which the conductor layer is formed so as not to protrude from the surface of the insulating substrate. Thus, by forming the conductor layer at the bottom of the groove, the edge distance between the conductor layers becomes longer than when the conductor layer is formed on the surface of the insulating substrate. Further, the protective layer covering the conductor layer is formed so as not to protrude from the surface of the insulating base material, thereby preventing the protective layer from being damaged. Therefore, a short circuit due to migration can be prevented more reliably.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a part of the wiring board 10 cut out. On the surface of the insulating substrate 11, a groove 12 is provided at a wiring pattern forming position, and a conductor layer 13 is formed at the bottom of the groove 12. Further, a protective layer 14 is formed in the groove 12 in which the conductor layer 13 is formed so as not to protrude from the surface of the insulating base material 11.

  FIG. 2 shows a wiring pattern forming method. FIG. 2A shows the insulating substrate 11. The insulating substrate 11 is made of an insulating synthetic resin such as ABS resin (acrylonitrile / butadiene / styrene resin) or polycarbonate resin. If a synthetic resin is used in this way, a wiring board having a desired shape can be easily generated by a molding process such as injection molding. Further, by forming a convex portion at a wiring pattern forming position of a mold used for molding, a groove 12 is formed at the wiring pattern forming position on the surface of the insulating base material 11 when molding a wiring board having a desired shape. Are provided at the same time. For this reason, it is not necessary to provide the process of producing | generating the insulating base material 11 and the process of forming the groove | channel 12 with respect to the insulating base material 11 separately. Furthermore, mass production of the insulating substrate 11 provided with the grooves 12 can be easily performed, and variations in the width and depth of the grooves 12 between the insulating substrates can be reduced.

  A conductor layer 13 is provided at the bottom of the groove 12 as shown in FIG. 2B. The conductor layer 13 is formed using a conductive member, for example, a so-called conductive paste containing conductive particles and a resin component. Examples of the conductive particles include tin (Sn), indium (In), bismuth (Bi), silver (Ag), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), gallium ( Examples thereof include metals such as Ga), silver (Ag), and thallium (Tl), and alloys made of these metals. Examples of the resin component include thermosetting of epoxy resin, urethane resin, acrylic resin, silicon resin, phenol resin, melamine resin, alkyd resin, urea resin, acrylic resin, unsaturated polyester resin, etc. Can be mentioned. Moreover, it is good also as what uses a thermoplastic resin, a photocurable resin, etc.

  Such a conductive member is applied to the bottom of the groove 12 using a technique such as screen printing or offset printing, or using a dispenser. Thereafter, the conductive layer 13 is formed by applying heat or evaporating and drying the conductive member. Here, the layer thickness of the conductor layer 13 is set so that the protective layer 14 can be formed in the groove 12 in which the conductor layer 13 is formed.

  As shown in FIG. 2C, a protective layer 14 is provided in the groove 12 provided with the conductor layer 13 so as not to protrude from the surface of the insulating substrate 11. The protective layer 14 is formed using a moisture-proof sealing member. As the sealing member, for example, a fluorine coating agent in which a fluororesin is dissolved in a fluorine-based solvent to form a solution is used. Further, if the sealing member has an appropriate viscosity, the conductive layer 13 is formed on the sealing member using a method such as screen printing or offset printing or a dispenser, as in the case of applying the conductive member. Can be applied to the groove 12. As a sealing member having an appropriate viscosity, for example, polyurethane resin or silicon resin can be used.

  In this way, the groove 12 is provided at the wiring pattern forming position on the surface of the insulating base material 11, and the conductor layer 13 and the protective layer 14 are sequentially disposed in the groove 12 so as not to protrude from the surface of the insulating base material 11. By providing, the wiring board 10 is formed. For this reason, in the wiring board 10, the edge distance between adjacent conductor layers is longer than when a conductor layer is provided on the surface of the insulating base. Moreover, since a conductor layer is coat | covered with the protective layer formed using the sealing member which has moisture resistance, the short circuit between the conductor layers by migration can be prevented. Moreover, in the wiring board 10, since it forms so that the protective layer 14 may not protrude from the surface of the insulating base material 11, when the protective layer 14 is formed protruding from the surface of the insulating base material, Compared with other parts, it becomes difficult to contact and the damage of the protective layer 14 can be prevented. Therefore, a short circuit between conductor layers due to migration can be prevented more reliably. Further, since the protective layer 14 does not protrude from the surface of the insulating base material, as shown in FIG. 3, other parts 21 and the like can be provided in close contact with the surface on which the groove 12 is provided. . Furthermore, if the protective layer 14 is formed using an insulating sealing member, the conductor layer 13 and the component 21 can be reliably insulated when the component 21 has conductivity. Here, if the protective layer 14 is formed using a sealing member having a high dielectric constant, a higher insulating property can be obtained as compared with the case where a sealing member having a low dielectric constant is used. Even if it is thin, it becomes possible to ensure desired insulation.

  In addition, if the protective layer 14 is formed using a sealing member having a low dielectric constant, the parasitic capacitance of the conductor layer 13 is small compared to the case where a sealing member having a high dielectric constant is used, and the signal flowing through the conductor layer 13 is reduced. The delay can be reduced.

  When the conductor layer 13 and the protective layer 14 are formed in the groove 12, if a dispenser is used, even if the insulating base material 11a has a three-dimensional shape as shown in FIG. The conductor layer 13 and the protective layer 14 can be easily formed by applying a conductive member or a sealing member to the groove 12 provided.

  Furthermore, even if the insulating base material has a three-dimensional shape, the conductor layer 13 and the protective layer 14 can be formed. Therefore, by using the casing of the electronic device as the insulating base material, a wiring cable, a flexible substrate, etc. Wiring parts can be reduced.

  FIG. 5 shows a configuration when the casing of the electronic device is used as an insulating substrate. Further, in FIG. 5, a schematic cross-sectional view at the position of the groove 12 is shown for the insulating base material 11b which is a casing.

  A groove 12 is provided on the inner surface of the insulating substrate (housing) 11b, and the conductive layer 13 and the protective layer 14 are formed by applying a conductive member or a sealing member to the groove 12. Connection regions 131 ct and 132 ct are provided at both ends of the conductor layer 13. The connection regions 131ct and 132ct are configured such that the protective layer 14 is not provided so that electrical connection with the conductor layer 13 is possible. In the connection regions 131ct and 132ct in which the protective layer 14 is not provided, a short circuit between the conductor layers due to migration can be prevented by increasing the distance between the conductor layers 13 to increase the edge distance.

  It is assumed that the electronic device is provided with circuit blocks 31 and 32, for example. The circuit block 31 is provided with a terminal 31ct, and the terminal 31ct of the circuit block 31 is electrically connected to the connection region 131ct of the conductor layer 13 when the electronic device is assembled. Similarly, the terminal 32ct is provided in the circuit block 32, and the terminal 32ct of the circuit block 32 is electrically connected to the connection region 132ct of the conductor layer 13 when the electronic device is assembled.

  For this reason, for example, a component 33 is provided between the circuit block 31 and the circuit block 32 so that a space for providing a wiring cable, a flexible substrate, and the like for connecting the circuit block 31 and the circuit block 32 cannot be secured. Even in such a case, the circuit block 31 and the circuit block 32 can be electrically connected by providing the groove 12 in the insulating base material (housing) 11b to form the conductor layer 13 and the protective layer 14. it can. Even when the component 33 is housed in a metal case and the component 33 and the insulating substrate (housing) 11b are assembled in contact with each other, a protective layer is formed using an insulating sealing member. By forming 14, insulation between the component 33 and the conductor layer 13 can be secured. Further, since the protective layer 14 is formed so as not to protrude from the inner surface of the insulating substrate (housing) 11b, the protective layer 14 is less likely to be damaged, and the short-circuiting between the conductor layers due to migration is more reliably performed. Can be prevented.

  FIG. 5 shows the case where the terminal 31ct is electrically connected to the connection region 131ct and the terminal 32ct is brought into contact with the connection region 132ct, but a connector is provided in the connection regions 131ct and 132ct. If the circuit blocks 31 and 32 are connected, the electrical connection between the conductor layer 13 and the circuit blocks 31 and 32 can be more reliably performed. Further, as shown in FIGS. 4 and 5, the present invention is not limited to the case where the groove 12 is provided on the inner surface of the insulating base (housing) to form the conductor layer 13 and the protective layer 14, but the insulating base (housing) The conductor layer 13 and the protective layer 14 may be formed by providing the groove 12 on the outer surface of the body.

It is a perspective view which shows a part of wiring board. It is a figure for demonstrating the wiring pattern formation method. It is a figure which shows the state in which the other components were provided. It is a figure which shows the case where an insulating base material is a three-dimensional shape. It is a figure which shows the case where a housing | casing is used as an insulating base material.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Wiring board, 11, 11a, 11b ... Insulating base material, 12 ... Groove, 13 ... Conductor layer, 14 ... Protective layer, 21, 33 ... Parts, 31, 32 ... Circuit block, 31ct, 32ct ... Terminal, 131ct, 132ct ... Connection area

Claims (5)

Providing a groove in the wiring pattern formation position on the surface of the insulating substrate;
Forming a conductor layer at the bottom of the groove;
A wiring pattern forming method comprising: forming a protective layer in a groove in which the conductor layer is formed so as not to protrude from the surface of the insulating substrate. 2. The wiring pattern forming method according to claim 1, wherein a synthetic resin is used as the insulating substrate, and the grooves are provided on the surface of the insulating substrate by molding. The conductor layer is formed by applying a conductive member to the groove with a dispenser, and the conductor layer is formed by applying a sealing member to the groove in which the conductor layer is formed with a dispenser. The wiring pattern forming method according to claim 1. A groove is provided on the surface of the insulating substrate,
Forming a conductor layer at the bottom of the groove;
A wiring board, wherein a protective layer is formed in a groove in which the conductor layer is formed so as not to protrude from the surface of the insulating base material. A groove is provided on the surface of the housing having insulating properties,
Forming a conductor layer on the bottom of the groove;
In the groove where the conductor layer is formed, a protective layer is formed so as not to protrude from the surface of the housing,
An electronic device characterized in that electrical connection between circuits is performed using the conductor layer.

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