JP2008004960A - Printed wiring board and circuit device - Google Patents

Abstract

An object of the present invention is to provide a printed wiring board made of a metal-coated polyimide having a two-layer structure in which an insulation resistance value hardly changes.
A conductive metal laminated via a sputtering metal layer is formed on at least one surface of an insulating film, and the sputtering metal layer and the conductive metal layer are selectively removed by an etching method to form a wiring. After forming the pattern, the laminated film is treated with a first solution capable of dissolving Ni contained in the sputtering metal layer, and then the Cr contained in the sputtering metal layer is dissolved and the sputtering metal layer of the insulating film is formed. It processes with the 2nd process liquid which can be removed, and the sputtering metal which remain | survives on the surface layer surface of the insulating film in which this wiring pattern is not formed is removed with an insulating film surface layer surface. Furthermore, in the printed wiring board of the present invention, the thickness of the insulating film in the portion where the wiring pattern is not formed is 1 to 100 nm thinner than the thickness of the insulating film where the wiring pattern is formed.
[Selection] Figure 4

Description

  The present invention relates to a printed wiring board in which a wiring pattern is directly formed on a surface of a polyimide film without an adhesive layer, and a circuit device in which an electronic component is mounted on the printed wiring board. More specifically, the present invention relates to a printed wiring board formed of a two-layer board comprising a polyimide film as a board and a metal layer formed on the surface of the insulating board, and an electronic component mounted on the printed wiring board. Related to the circuit device.

Conventionally, a wiring board is manufactured using a copper-clad laminate in which a copper foil is laminated using an adhesive on the surface of an insulating film such as a polyimide film.
The copper-clad laminate as described above is manufactured by thermocompression bonding a copper foil to an insulating film having an adhesive layer formed on the surface. Therefore, when manufacturing such a copper-clad laminate, the copper foil must be handled alone. However, the thinner the copper foil, the weaker the waist, and the lower limit of the copper foil that can be handled alone is about 9 to 12 μm. When using a copper foil thinner than this, for example, a copper foil with a support may be used. The handling becomes very complicated. In addition, using an adhesive on the surface of the insulating film, forming a wiring pattern using a copper-clad laminate with a thin copper foil attached as described above, the adhesive used to attach the copper foil Warp deformation of the printed wiring board occurs due to heat shrinkage. In particular, as electronic devices become smaller and lighter, printed wiring boards are becoming thinner and lighter, and such printed wiring boards have a three-layered copper-clad laminate consisting of an insulating film, adhesive, and copper foil. It is becoming impossible to handle with a board.

  Therefore, in place of such a three-layered copper-clad laminate, a two-layer structure in which a metal layer is directly laminated on the surface of an insulating film is used. Such a two-layered laminate is produced by depositing a seed layer metal on the surface of an insulating film such as a polyimide film by electroless plating, vapor deposition, sputtering, or the like. And after making copper plating adhere to the surface of the metal deposited as mentioned above, a desired wiring pattern can be formed by apply | coating a photoresist, exposing and developing, and then etching. In particular, a laminate having a two-layer structure is suitable for manufacturing a very fine wiring pattern in which a wiring pattern pitch width formed by a thin metal (Cu) layer is less than 30 μm.

  By the way, in Patent Document 1 (Japanese Patent Laid-Open No. 2003-188495), a first metal layer formed on a polyimide resin film by a dry film forming method and a conductivity formed on the first metal layer by a plating method are disclosed. In a method for manufacturing a printed wiring board, in which a pattern is formed by an etching method on a metal-coated polyimide film having a second metal layer, a wiring for purines or the like, wherein the etching surface is subjected to a cleaning treatment with an oxidizing agent after the etching An invention of a method for manufacturing a substrate is disclosed. Example 5 of Patent Document 1 shows an example in which a nickel-chromium alloy is plasma-deposited to a thickness of 10 nm, and then copper is deposited to a thickness of 8 μm by a plating method.

  A fine wiring pattern can be formed by using the metal-coated polyimide film having a two-layer structure formed as described above. However, a metal layer is deposited on the surface of the polyimide film as a base material by, for example, plasma deposition. If it does, the metal which vapor-deposits and the component which forms a polyimide may couple | bond part chemically on the polyimide film surface, and such a metal is hard to be removed by an etching. Therefore, a trace amount of metal may be integrated with the polyimide film on the polyimide film surface on which the wiring pattern is formed. Thus, the insulation between wiring patterns may fall by the metal which remain | survives on the polyimide film surface. Also, as shown in FIG. 7, after the wiring pattern is formed as described above, the wiring pattern may be plated before the electronic component is mounted. The metal forming the layer 15 may remain bonded to the component forming the polyimide film 11. Such a remaining metal 30 may be physically bonded to the surface of the polyimide film 11 or may be chemically bonded to a component forming the polyimide film. When such residual metal 30 is chemically bonded to the polyimide film 11, it is difficult to completely remove such metal 30 by etching.

After a wiring pattern composed of the first metal layer 15 and the second metal layer 20 is formed on the surface of the polyimide film 11, such a wiring pattern may be protected by forming a plating layer 25 on the surface. In many cases, such a plated layer is formed by electroless plating. The metal 30 remaining on the polyimide film often becomes the starting point of metal deposition during such metal deposition by electroless plating. For example, as indicated by reference numeral 31 in FIG. The metal 31 may impair the electrical insulation of the polyimide film surface, which is inherently electrically insulating. When such deposited metal 31 is present on the surface of the polyimide film 11, there arises a problem that the electrical insulation between the wiring patterns is impaired due to migration between the wiring patterns via the deposited metal 31. I understood. In particular, due to such migration, the insulation resistance between the wiring patterns at the time of manufacture shows a good value. For example, the insulation resistance after applying voltage for 1000 hours or more is considerably lower than the value before applying the voltage. Become.
JP 2003-188495 A

  The present invention relates to a printed wiring board using a metal-coated polyimide film having a two-layer structure that is specifically generated by using the metal-coated polyimide film having the two-layer structure as described above. The purpose is to solve the problem.

That is, an object of the present invention is to provide a printed wiring board in which the insulation resistance value is unlikely to vary by using a metal-coated polyimide film having a two-layer structure.
Another object of the present invention is to provide a printed wiring board in which the insulation resistance value formed as described above is unlikely to fluctuate.

  Another object of the present invention is to provide a circuit device in which an electronic component is mounted on the printed wiring board as described above.

  In the printed wiring board of the present invention, the copper layer laminated on the surface of the polyimide film via the sputtering metal layer is selectively removed by an etching method to form a wiring pattern. The surface of the polyimide film on which the wiring pattern is not formed is removed together with the remaining sputtering metal with a second treatment solution capable of dissolving Ni and then dissolving the Cr and dissolving the polyimide. It is characterized by doing. That is, in the method for producing a printed wiring board of the present invention, a laminated film having a conductive metal layer made of a conductive metal laminated via a sputtering metal layer is formed on at least one surface of an insulating film, A sputtering metal layer and a conductive metal layer formed on the film are selectively removed by an etching method to form a wiring pattern, and then the laminated film is first dissolved in Ni contained in the sputtering metal layer. Surface of the insulating film on which the wiring pattern is not formed by treatment with a second treatment liquid capable of dissolving Cr contained in the sputtering metal layer and then removing the sputtering metal layer of the insulation film. Can be produced by removing the remaining sputtering metal together with the surface of the insulating film.

  Moreover, the printed wiring board of the present invention is a printed wiring board having a polyimide film and a wiring pattern formed on at least one surface of the polyimide film, where the wiring pattern of the polyimide film is formed. The thickness of the polyimide film is 1 to 100 nm thicker than the portion where the wiring pattern is not formed. That is, the printed wiring board of the present invention is a printed wiring board having an insulating film and a wiring pattern formed on at least one surface of the insulating film, and a portion where the wiring pattern of the insulating film is not formed. The thickness of the insulating film is 1 to 100 nm thinner than the thickness of the insulating film on which the wiring pattern is formed.

  Furthermore, the circuit device of the present invention is characterized in that an electronic component is mounted on a wiring pattern formed on the printed wiring board.

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