JP2010056495A - Method of forming wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for surly forming a wiring board that is excellent in adhesion property between insulation layers, and between the insulation layer and a wiring conductor, and excellent in electrical insulation reliability between wiring conductors. <P>SOLUTION: The method of manufacturing the wiring board includes: a step of adhering a resin film 2 on the main surface of an insulation sheet 1 being the insulation layer 11 of the wiring board 10 with an adhesive layer 3; a step of forming a through-hole 4 into the insulation sheet 1 to which the resin film 2 is adhered with the adhesive layer 3 wherein the insulation sheet 1 is opened the through-hole together with the resin film 2 and the adhesive layer 3; a step of filling the through-hole 4 with conductive paste 5; and a step of removing the resin film 2 together with the adhesive layer 3 from the main surface of the insulation sheet 1 having the through-hole 4 filled with the conductive paste 5. The adhesive layer 3 includes a colored adhesive layer 3a on a side contacting with the resin film 2, and a colorless adhesive layer 3b on a side contacting with the insulation sheet 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention attaches a resin film to an insulating sheet serving as an insulating layer of a wiring board through an adhesive layer, and drills a through hole penetrating the insulating sheet together with the resin film and the adhesive layer by laser processing, The present invention relates to a method for manufacturing a wiring board including a step of filling the through-hole with a conductive paste and then peeling and removing the resin film together with the adhesive layer from the main surface of an insulating sheet.

  Conventionally, as a wiring board used for mounting electronic components such as semiconductor elements, an insulating layer formed by heat-curing an insulating sheet impregnated with a thermosetting resin into a heat-resistant fiber base material such as glass cloth and copper While alternately laminating wiring conductors made of metal foil such as foil, the conductive paste filled in the through holes formed in the insulating layer is cured between the wiring conductors positioned above and below the insulating layer. 2. Description of the Related Art A wiring board that is electrically connected by a through conductor is known.

This wiring board is manufactured as follows, for example.
(A) A resin film having a thickness of about 5 to 15 μm made of polyethylene terephthalate is formed on both main surfaces of an insulating sheet impregnated with an uncured thermosetting resin on a heat resistant fiber base material, and an adhesive layer made of an acrylic adhesive is provided. To stick through.
(B) Next, the insulating sheet with the resin film attached thereto is subjected to laser processing from above the resin film, thereby forming a through-hole penetrating the insulating sheet together with the resin film and the adhesive layer.
(C) Next, a conductive paste containing conductive powder such as metal is filled into the through-holes from above the resin film by screen printing (press-fit). In this case, a resin film having through holes is used as a mask for printing.
(D) Next, the resin film together with the adhesive layer is removed from both main surfaces of the insulating sheet filled with the conductive paste in the through holes.
(E) Next, a wiring conductor made of a metal foil previously formed in a predetermined pattern on the transfer film is pressed against at least one main surface of the insulating sheet so as to cover the end of the conductive paste. And laminate.
(F) Next, a plurality of insulating sheets on which wiring conductors are laminated are stacked, and heated and pressed using a hot press at a temperature of 180 to 240 ° C. for several minutes to several hours to cure the insulating sheet and the conductive paste. To obtain a wiring board.

  However, in the method as described above, when the resin film is peeled and removed together with the adhesive layer from the insulating sheet filled with the conductive paste in the through holes, a part of the adhesive layer is peeled off from the resin film side for insulation. Sometimes left on the sheet. If the adhesive layer remains on the insulating sheet in this manner, when the insulating sheet is laminated to obtain a wiring board, the adhesive layer is sandwiched between the insulating layers constituting the wiring board or between the insulating layer and the wiring conductor. As a result, the adhesion between the insulating layers or between the insulating layer and the wiring conductor is hindered, or the electrical insulation reliability between the wiring conductors is reduced.

Thus, the adhesive layer remaining on the insulating sheet can be removed by peeling off, but the adhesive layer made of acrylic adhesive is usually transparent, so that the adhesive layer remaining on the insulating sheet is not recognized. There was a problem that it was difficult. Therefore, it is conceivable that the adhesive layer is colored by mixing a colorant such as a pigment, thereby facilitating recognition of the adhesive layer remaining on the insulating sheet. However, when a colorant such as a pigment is mixed in the adhesive layer and colored, the colorant of the adhesive layer adheres to the insulating sheet and contaminates the insulating sheet. As a result, a stain caused by the colorant is formed on the surface of the wiring board. Will result in poor appearance.
JP 2003-283129 A

  The problem of the present invention is that even when the adhesive layer remains on the insulating sheet when the resin film is peeled off and removed from the insulating sheet serving as the insulating layer of the wiring board, the remaining adhesive layer is well recognized. Wiring that can be reliably removed, and thereby can reliably manufacture a wiring board that has excellent adhesion between insulating layers and between the insulating layer and the wiring conductor, and excellent electrical insulation reliability between the wiring conductors. It is to provide a method for manufacturing a substrate.

  The method for manufacturing a wiring board according to the present invention includes a step of attaching a resin film to the main surface of an insulating sheet serving as an insulating layer of the wiring board via an adhesive layer, and the resin film is attached via the adhesive layer. Further, a step of perforating a through hole penetrating the insulating sheet together with the resin film and the adhesive layer, a step of filling the through hole with a conductive paste, and the conductive paste in the through hole A method for producing a wiring board comprising: removing the resin film together with the adhesive layer from the main surface of the filled insulating sheet, wherein the adhesive layer is a colored adhesive on the side in contact with the resin film. And a non-colored adhesive layer on the side in contact with the insulating sheet.

  According to the method for manufacturing a wiring board of the present invention, the adhesive layer for adhering the resin film to the insulating sheet is composed of a colored adhesive layer on the side in contact with the resin film and an uncolored adhesive layer on the side in contact with the insulating sheet. Therefore, even if a part of the adhesive layer remains on the insulating sheet when the resin film is peeled off and removed from the insulating sheet, the adhesive layer is colored and easily recognized and removed. Accordingly, it is possible to reliably manufacture a wiring substrate that has excellent adhesion between insulating layers and between the insulating layer and the wiring conductor, and excellent electrical insulation reliability between the wiring conductors. Further, since the side of the adhesive layer in contact with the insulating sheet is a non-colored adhesive layer, the pigment contained in the adhesive layer does not contaminate the insulating sheet.

  Next, a method for manufacturing a wiring board according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1A to FIG. 4J are schematic explanatory diagrams for each process for explaining a method of manufacturing a wiring board according to this embodiment, and FIG. 5 is an enlarged view of a main part in FIG. FIG. FIG. 6 is an enlarged view of a main part in FIG.

  First, as shown to Fig.1 (a), the insulating sheet 1 used as the insulating layer of a wiring board and the resin film 2 with the adhesion layer 3 are prepared.

  The insulating sheet 1 is a rectangle having a thickness of about 30 to 200 μm, a width and a length of about 20 to 60 cm, respectively, and a heat-resistant fiber base material obtained by weaving a bundle of heat-resistant fibers vertically and horizontally into a sheet shape, and uncured thermosetting. After impregnating with a functional resin, it is in a dry or semi-cured state. As the heat-resistant fiber, for example, glass fiber, aramid fiber, wholly aromatic ester fiber, or the like is used, and as the thermosetting resin, for example, epoxy resin, bismaleimide triazine resin, allyl-modified polyphenylene ether resin, or the like is used.

  The resin film 2 has a thickness of about 5 to 15 μm and is made of a heat resistant resin such as polyethylene terephthalate. And the adhesion layer 3 which consists of an acrylic resin adhesive on the one main surface is adhere | attached.

  As shown in the enlarged view of the main part in FIG. 5, the adhesive layer 3 includes a colored adhesive layer 3a containing a colorant such as a pigment on the resin film 2 side and a non-colored adhesive layer 3b containing no colorant on the resin sheet 1 side. And have. The thickness of the colored adhesive layer 3a is about 2 to 4 μm, and the thickness of the non-colored adhesive layer 3b is about 5 to 10 μm. Various colorants can be used as the colorant contained in the colored adhesive layer 3a, but those having a large contrast difference or color difference from the insulating sheet 1 are preferred, particularly red, pink, blue and the like. It is preferable to use a conspicuous one.

  Next, as shown in FIG. 1 (b), the film 2 is adhered to the upper and lower main surfaces of the insulating sheet 1 via the adhesive layer 3. At this time, the side of the pressure-sensitive adhesive layer 3 that contacts the insulating sheet 1 is the non-colored pressure-sensitive adhesive layer 3b that does not contain a colorant, so that the colorant does not adhere to the insulating sheet 1. Therefore, the stain resulting from a coloring agent does not generate | occur | produce in the wiring board manufactured by this invention.

  Next, as shown in FIG.1 (c), the several through-hole 4 is formed in the insulating sheet 1 to which the resin film 2 was stuck up and down via the adhesion layer 3. As shown in FIG. Formation of the through-hole 4 is performed by irradiating a laser beam from the upper surface side to the insulating sheet 1 to which the resin film 2 is stuck up and down via the adhesive layer 3.

  Next, as shown in FIG. 2 (d), the conductive paste 5 is filled into the through holes 4. In order to fill the through hole 4 with the conductive paste 5, the conductive paste 5 is supplied onto the resin film 2 on the upper surface side, and the conductive paste 5 is slid while sliding with a hard rubber squeegee. A filling method is adopted. At this time, the resin film 2 on the upper surface side functions as a mask for filling the through holes 4 with the conductive paste 5.

  The conductive paste 4 is, for example, a metal powder made of an alloy of tin, silver, bismuth and copper and a triazine system such as triallyl cyanurate, triallyl isocyanurate, trisepoxypropyl isocyanurate, tris (2-hydroxyethyl) isocyanurate. Containing thermosetting resin. And it exhibits electroconductivity by contact between the metal powders. In addition, the content of the metal powder is preferably 80 to 95% by weight with respect to the total amount of the conductive paste 4. When the content of the metal powder is less than 80% by weight, the connection between the metal powders is hindered by the triazine-based thermosetting resin, and the conduction resistance tends to increase. When the content exceeds 95% by weight, the metal powder and There is a tendency that the viscosity of the conductive paste containing the triazine-based thermosetting resin is so high that it cannot be satisfactorily filled. Therefore, the content of the metal powder is preferably 80 to 95% by weight.

  Next, as shown in FIG. 2 (e), the resin film 2 is peeled and removed together with the adhesive layer 3 from both main surfaces of the insulating sheet 1. At this time, even if a part of the adhesive layer 3 is peeled off from the resin film 2 and remains on the insulating sheet 1 as shown in the enlarged view of the main part in FIG. 6, the remaining adhesive layer 3 is in close contact with the insulating sheet 1. Since the colored adhesive layer 3a is present on the opposite side, the difference in contrast with the insulating sheet 1 and the difference in color tone are recognized and reliably removed by human eyes or using an image recognition device. Can do. In order to remove the pressure-sensitive adhesive layer 3 remaining on the insulating sheet 1, an object having a stronger adhesive force than the insulating sheet 1 is pressed against the pressure-sensitive adhesive layer 3 and then the pressure-sensitive adhesive 3 together with the object. May be peeled off from the insulating sheet 1.

  Next, as shown in FIG. 3 (f), a wiring made of a metal foil such as a copper foil that is detachably adhered to one main surface of a transfer film 6 made of a resin film such as polyethylene naphthalate. A conductor 7 is prepared. The wiring conductor 7 on the transfer film 6 is made to adhere a metal foil such as a copper foil to one main surface of the transfer film 6 via an adhesive (not shown), and then the metal foil is bonded to a predetermined surface by a photolithography technique. It is formed by etching into a pattern. The thickness of the wiring conductor 7 is about 5 to 30 μm.

  Next, as shown in FIG. 3G, the wiring conductor 7 on the transfer film 6 is laminated on the insulating sheet 1 by overlapping and pressing so as to cover the end of the conductive paste 5, As shown in 3 (h), the wiring conductor 7 is transferred by removing the transfer film 6.

  Next, as shown in FIG. 4 (i), the insulating sheet 1 in which the conductive paste 5 is filled in the through hole 4 and the wiring conductor 7 is transferred to the surface as described above is used for manufacturing the wiring board. A plurality of sheets are prepared in a necessary form (the case where there are three insulating sheets 1 is shown here).

  Next, as shown in FIG. 4 (j), the plurality of insulating sheets 1 are heated while being pressed in a state where they are superposed vertically in a predetermined arrangement, and the thermosetting resin and the conductive paste 5 of the insulating sheet 1 are heated. Insulating layers 11 and wiring conductors 7 in which a plurality of insulating sheets 1 are cured are alternately laminated, and upper and lower wirings are formed by through conductors 15 in which conductive paste 5 is cured. A wiring board 10 to which the conductors 7 are electrically connected is obtained. At this time, according to the present invention, since the adhesive layer 3 on each insulating sheet 1 is completely removed, the adhesiveness between the insulating layers 11 and between the insulating layer 11 and the wiring conductor 7 is excellent, and the wiring conductor A wiring board having excellent electrical insulation reliability between the seven can be reliably manufactured.

(A)-(c) is a schematic sectional drawing for every process for demonstrating the manufacturing method of the wiring board of this invention. (D)-(e) is a schematic sectional drawing for every process for demonstrating the manufacturing method of the wiring board of this invention. (F)-(h) is a schematic sectional drawing for every process for demonstrating the manufacturing method of the wiring board of this invention. (I), (j) is a schematic sectional drawing for every process for demonstrating the manufacturing method of the wiring board of this invention. These are the principal part enlarged views in Fig.1 (a). These are the principal part enlarged views in FIG.2 (e).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulation sheet 2 Resin film 3 Adhesive layer 3a Colored adhesive layer 3b Uncolored adhesive layer 4 Through-hole 5 Conductive paste 10 Wiring board

Claims (1)

  A step of adhering a resin film to the main surface of an insulating sheet serving as an insulating layer of the wiring board via an adhesive layer; and the insulating sheet on which the resin film is adhered via the adhesive layer. From the main surface of the insulating sheet filled with the conductive paste in the through-hole, the step of punching a through-hole penetrating the resin film and the adhesive layer together, the step of filling the through-hole with the conductive paste A method of manufacturing a wiring board including the step of peeling and removing the resin film together with the adhesive layer, wherein the adhesive layer is a colored adhesive layer on the side in contact with the resin film and an insulating sheet on the side in contact with the insulating sheet. A method for producing a wiring board, comprising: a colored adhesive layer.

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