JP2014090110A - Wiring board manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board having high insulation reliability between wiring conductors.SOLUTION: A wiring board manufacturing method comprises: forming a plurality of through holes 3a, 3b in insulation sheets 1a, 1b; subsequently filling the through holes 3a, 3b with conductive pastes 5a, 5b so as to protrude from both sides of the insulation sheets 1a, 1b; subsequently transferring and embedding wiring conductors 6a, 6b in both sides of the insulation sheets 1a so as to cover the conductive paste 5a; subsequently transferring and embedding a wiring conductor 6c on one side of the insulation sheet 1b so as to cover the conductive paste 5b and stacking the other surface of the insulation sheet 1b on one surface of the insulation sheet 1a; subsequently hardening the insulation sheets 1a, 1b and the conductive pastes 5a, 5b. A sum of heights of both ends of the conductive paste 5a, which protrude from both surfaces of the insulation sheet 1 is set to be smaller than a sum of heights of both ends of the conductive paste 5b, which protrude from the insulation sheet 1b.

Description

  The present invention relates to a method of manufacturing a wiring board used for mounting a semiconductor element such as a semiconductor integrated circuit element.

  As a method of manufacturing a wiring board for mounting a semiconductor element such as a semiconductor integrated circuit element, there is a method using a transfer method for forming a wiring conductor.

  A conventional example of such a method of manufacturing a wiring board will be described with reference to FIGS. First, as shown to Fig.7 (a), the insulating sheet 11a and resin film 12a * 12b are prepared. The insulating sheet 11a is a rectangle having a thickness of about 30 to 200 μm, a width and a length of about 20 to 60 cm, respectively. The resin composition is impregnated and then dried or semi-cured. The resin films 12a and 12b have a thickness of about 10 to 30 μm, and a film made of a thermoplastic resin such as polyethylene terephthalate is used.

  Next, as shown in FIG.7 (b), resin film 12a * 12b is stuck to the upper and lower main surfaces of the insulating sheet 11a so that peeling is possible through the adhesive layer which is not shown in figure. Next, as shown in FIG.7 (c), the several through-hole 13a is formed in the insulating sheet 11a by which resin film 12a * 12b was stuck on the upper and lower surfaces. The through-hole 13a is formed by placing the insulating sheet 11a with the resin films 12a and 12b attached on the top and bottom on a flat suction table (not shown) and irradiating laser light from the upper surface side. At this time, a ring-shaped protrusion 14 formed by melting a part of the resin film 12b in the opening of the through hole 13a is formed on the resin film 12b on the upper surface side.

  Next, as shown in FIG. 8A, the conductive paste 15a is filled into the through holes 13a that connect the resin films 12a and 12b and the insulating sheet 11a. In order to fill the through hole 13a with the conductive paste 15a, the conductive paste 15a is supplied onto the resin film 12b on the upper surface side, and a squeegee made of hard rubber is slid on the conductive paste 15a while scraping the conductive paste 15a. A filling method is adopted. At this time, the conductor paste 15a filled in the through hole 13a is filled up to the height of the protrusions 14.

  Next, as shown in FIG.8 (b), resin film 12a * 12b is peeled and removed from both the main surfaces of the insulating sheet 11a. At this time, the conductor paste 15a filled in the through-hole 13a protrudes from the upper and lower surfaces of the insulating sheet 11a by a height corresponding to the thickness of the resin films 12a and 12b. In addition, the conductor paste 15a protruding to the upper surface side of the insulating sheet 11a further increases the height of the protrusion 14.

  Next, as shown in FIG. 9A, wiring conductors 16a and 16b made of metal foil such as copper foil are separately provided on one main surface of support films 17a and 17b made of resin film such as polyethylene naphthalate. Transfer sheets 18a and 18b attached so as to be peelable are prepared. The wiring conductors 16a and 16b of the transfer sheets 18a and 18b are formed by attaching a metal foil such as a copper foil to one of the main surfaces of the support films 17a and 17b with an adhesive (not shown) between them, It is formed by etching into a predetermined pattern by a photolithography technique. The thickness of the wiring conductors 16a and 16b is about 5 to 30 μm.

  Next, as shown in FIG. 9B, the transfer sheets 18a and 18b are stacked on the upper and lower surfaces of the insulating sheet 11a and pressed from above and below so that the wiring conductors 16a and 16b cover the ends of the conductor paste 15a. After embedding the wiring conductors 16a and 16b in the insulating sheet 11a, as shown in FIG. 9C, the supporting films 17a and 17b are removed to transfer the wiring conductors 16a and 16b to both surfaces.

  Further, as shown in FIG. 10 (a), a wiring conductor made of an insulating sheet 11b filled with a conductive paste 15b in a through hole 13b and a metal foil such as a copper foil on one main surface of a support film 17c. A transfer sheet 18c to which 16c is detachably attached is separately prepared and placed on the insulating sheet 11a to which the wiring conductors 16a and 16b are transferred. The insulating sheet 11b and the conductive paste 15b are formed by the same material and the same method as the insulating sheet 11a and the conductive paste 15a. The transfer sheet 17c is formed of the same material and the same method as the transfer sheets 17a and 17b.

  Next, as shown in FIG. 10B, the insulating sheet 11b is overlaid on the insulating sheet 11a so that the wiring conductor 16b covers the end of the conductive paste 15b, and the wiring conductor 16c is the end of the conductive paste 15b. The transfer sheet 18c is stacked on the insulating sheet 11b so as to cover the sheet, and pressed from above and below to closely contact the conductor paste 15b and the wiring conductor 16b, and between the insulating sheet 11b, the insulating sheet 11a, and the wiring conductor 16a. At the same time, the wiring conductor 16c is embedded in the insulating sheet 11b.

  Finally, as shown in FIG. 10 (c), after forming the laminate by removing the support film 17c, the laminate is heated while being pressed from above and below to insulate the sheets 11a and 11b and the conductor paste 15a. The wiring board 20 is completed by thermally curing 15b.

  However, according to the above-described method, in the insulating sheet 11b, the wiring conductor 16c is embedded only on one surface thereof, but in the insulating sheet 11a, the wiring conductors 16a and 16b are embedded on both surfaces thereof. That is, the conductor paste 15b of the insulating sheet 11b is compressed by one layer of the wiring conductor 16c in addition to the height protruding from the upper and lower surfaces of the insulating sheet 11b, while the conductor paste 15a of the insulating sheet 11a is insulated. In addition to the height protruding from the upper and lower surfaces of the sheet 11a, the wiring conductors 16a and 16b are compressed by two layers. Therefore, the conductor paste 15a of the insulating sheet 11a is compressed more greatly than the conductor paste 15b of the insulating sheet 11b, and the conductor paste 15a that cannot be accommodated in the through hole 13a becomes the surface of the insulating sheet 11a and the wiring conductor 16b. Between the wire conductor 16b and the wire conductor 16b. Such protrusions reduce the electrical insulation reliability between the wiring conductors 16b.

JP 2010-109198 A JP 2009-260263 A

  It is an object of the present invention to provide a wiring board having high insulation reliability between wiring conductors by effectively preventing the conductor paste from protruding from the wiring conductor embedded in the insulating sheet.

  The method for manufacturing a wiring board according to the present invention includes a step of preparing first and second insulating sheets containing an uncured thermosetting resin, and a plurality of through holes formed in the first and second insulating sheets. A step of filling the through hole with a conductive paste so as to protrude from both sides of the first and second insulating sheets, and covering the conductive paste on both sides of the first insulating sheet. A step of transferring and embedding a wiring conductor made of a metal foil, and transferring and embedding the wiring conductor made of a metal foil so as to cover the conductor paste on one surface of the second insulating sheet; In the method for manufacturing a wiring board, comprising: laminating the other surface of the sheet on one surface of the first insulating sheet; and curing the first and second insulating sheets and the conductive paste. The sum of the heights of both of the conductor pastes protruding from both surfaces of one insulating sheet is set to be smaller than the sum of the heights of both of the conductor pastes protruding from both surfaces of the second insulating sheet. It is a feature.

  According to the wiring board of the present invention, the wiring conductor is transferred and embedded on one side with the sum of the heights of both conductor pastes protruding from both sides of the first insulating sheet on which the wiring conductor is transferred and embedded on both sides. Since the conductor paste protruding from both sides of the second insulating sheet is lower than the sum of both heights, the wiring conductor is transferred and embedded so as to cover the conductor paste on both sides of the first insulating sheet. In this case, it is possible to reduce the fact that the conductor paste of the first insulating sheet is greatly compressed. As a result, it is possible to effectively prevent the conductive paste from protruding from the wiring conductor embedded in the insulating sheet, and to provide a wiring board having high insulation reliability between the wiring conductors.

FIG. 1 is a schematic cross-sectional view for explaining an example of an embodiment of a method for manufacturing a wiring board according to the present invention. FIG. 2 is a schematic cross-sectional view for explaining an example of an embodiment of a method for manufacturing a wiring board according to the present invention. FIG. 3 is a schematic cross-sectional view for explaining an example of an embodiment of a method for manufacturing a wiring board according to the present invention. 4 is a schematic cross-sectional view for explaining an example of an embodiment of a method for manufacturing a wiring board of the present invention. FIG. 5 is a schematic cross-sectional view for explaining an example of an embodiment of a method for manufacturing a wiring board according to the present invention. FIG. 6 is a schematic cross-sectional view for explaining an example of an embodiment of a method for manufacturing a wiring board according to the present invention. FIG. 7 is a schematic cross-sectional view for explaining a conventional method for manufacturing a wiring board. FIG. 8 is a schematic cross-sectional view for explaining a conventional method for manufacturing a wiring board. FIG. 9 is a schematic cross-sectional view for explaining a conventional method for manufacturing a wiring board. FIG. 10 is a schematic cross-sectional view for explaining a conventional method for manufacturing a wiring board.

  Next, an example of an embodiment of the method for manufacturing a wiring board according to the present invention will be described with reference to FIGS. First, as shown in FIG. 1A, an insulating sheet 1a and resin films 2a and 2b are prepared.

  The insulating sheet 1a is obtained by impregnating an uncured thermosetting resin into a heat-resistant fiber base material obtained by weaving a bundle of heat-resistant fibers vertically and horizontally into a sheet shape, and then drying or semi-curing the sheet. It is a rectangle having a width of about 200 μm and a width and length of about 20-60 cm. Examples of the heat resistant fiber include glass fiber, aramid fiber, wholly aromatic ester fiber, and the like. As the thermosetting resin, for example, an epoxy resin, a bismaleimide triazine resin, an allyl-modified polyphenylene ether resin, or the like is used.

  The resin film 2a is made of a heat-resistant thermoplastic resin such as polyethylene terephthalate and has a thickness of about 5 to 15 μm. The resin film 2b is a laminated film in which two resin resin films 2ba and 2bb are detachably laminated, and the resin film 2ba has the same thickness as the resin film 2a, about 5 to 15 μm, and the resin film 2bb. Is about 20 to 100 μm thicker. The resin films 2ba and 2bb are both made of a heat-resistant thermoplastic resin such as polyethylene terephthalate. A pressure-sensitive adhesive layer (not shown) is attached to the surface of the resin films 2a and 2b on the insulating sheet 1a side.

  Next, as shown in FIG. 1B, the resin film 2a is adhered to the lower surface of the insulating sheet 1a via an adhesive layer, and the resin film 2b is adhered to the upper surface of the insulating sheet 1a via an adhesive layer. . In this case, the adhesion force between the resin film 2ba and the resin film 2bb is set to be weaker than the adhesion force between the resin film 2ba and the insulating sheet 1a.

  Next, as shown in FIG.1 (c), the some through-hole 3a is formed from the resin film 2b side in the insulating sheet 1a with which resin film 2a * 2b was stuck. The through-hole 3a is formed by placing the insulating sheet 1a on which the resin films 2a and 2b are adhered on a flat suction table (not shown) with the resin film 2a facing down and irradiating a laser beam from the upper surface side. Is done. At this time, in the resin film 2b on the upper surface side, a ring-shaped protrusion 4a formed by melting a part of the resin film 2bb on the upper surface side is formed in the opening of the through hole 3a.

  Next, as shown in FIG. 2A, the resin film 2bb on the upper surface side is peeled off from the resin film 2ba on the lower surface side in the resin film 2b. Thereby, the resin film 2ba without the ring-shaped protrusion 4a remains on the upper surface of the insulating sheet 1a. At this time, since the adhesive force between the resin film 2ba and the resin film 2bb is weaker than the adhesive force between the resin film 2ba and the insulating sheet 1a, even if the resin film 2bb is peeled off from the resin film 2ba, the resin film No peeling occurs between 2ba and the insulating sheet 1a, and the resin film 2bb can be peeled off from the resin film 2ba very easily and satisfactorily.

  Next, as shown in FIG. 2B, a conductor paste 5a is filled into the through hole 3a that communicates the insulating sheet 1 and the resin films 2a and 2ba. In order to fill the through hole 3a with the conductor paste 5a, the conductor paste 5a is supplied onto the resin film 2ba on the upper surface side, and a squeegee made of hard rubber is slid on the conductor paste 5a while scraping the conductor paste 5a. A filling method is adopted. At this time, since the protrusion 4a does not remain on the resin film 2ba on the upper surface side, the conductor paste 5a corresponding to the thickness of the resin film 2ba is filled in the through hole 3a of the resin film 2ba. Become.

  The conductive paste 5a is, for example, a metal powder made of an alloy of tin, silver, bismuth and copper and a triazine type such as triallyl cyanurate, triallyl isocyanurate, trisepoxypropyl isocyanurate or tris (2-hydroxyethyl) isocyanurate. Containing thermosetting resin. And electroconductivity is exhibited by the contact of metal powder. In addition, as for content of a metal powder, 80 to 95 weight% is preferable with respect to the total amount of the conductor paste 5a. 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 conductor 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 (c), resin film 2a * 2ba is peeled and removed from both main surfaces of the insulating sheet 1a. At this time, since the through-hole 3a of the resin film 2ba is filled with the conductor paste 5a corresponding to the thickness of the resin film 2ba as described above, the conductor paste 5a has the thickness of the resin films 2a and 2ba. It will be in the state which protruded from the upper and lower surfaces of the insulating sheet 1a by the part according to this. At this time, if the thickness of the resin films 2a and 2ba is less than 5 μm, the height of the conductor paste 5a protruding from the main surface of the insulating sheet 1a is low, and as will be described later, both surfaces of the insulating sheet 1a When the wiring conductors 6a and 6b are laminated so as to cover the end portions of the conductive paste 5a, there is a high risk that the adhesion between the conductive paste 5a and the wiring conductors 6a and 6b is weak, and conversely exceeds 15 μm. When the conductors 5a projecting from the main surface of the insulating sheet 1a have a high height, the wiring conductors 6a and 6b are stacked on the surface of the insulating sheet 1a so as to cover the end portions of the conductor paste 5a. In addition, there is a high risk that the protruding portion of the conductor paste 5a is largely crushed laterally and protrudes from the wiring conductors 6a and 6b. Therefore, the thickness of the resin films 2a and 2ba is preferably in the range of 5 to 15 μm.

  Next, as shown in FIG. 3A, wiring conductors 6a and 6b made of metal foil such as copper foil are separately provided on one main surface of support films 7a and 7b made of resin film such as polyethylene naphthalate. Transfer sheets 8a and 8b attached so as to be peelable are prepared. The wiring conductors 6a and 6b of the transfer sheets 8a and 8b are formed by attaching a metal foil such as a copper foil to one of the main surfaces of the support films 7a and 7b with an adhesive material (not shown) between them. It is formed by etching into a predetermined pattern by a photolithography technique. The thickness of the wiring conductors 6a and 6b is about 5 to 30 μm.

  Next, as shown in FIG. 3 (b), the wiring conductors 6a and 6b of the transfer sheets 8a and 8b are stacked on the insulating sheet 1a by overlapping and pressing so as to cover the ends of the conductive paste 5a. As shown in FIG. 3C, the wiring films 6a and 6b are transferred by removing the support films 7a and 7b. At this time, since the conductor paste 5a protrudes from the surface of the insulating sheet 1 by an appropriate height according to the thickness of the resin films 2a and 2ba, the conductor paste 5a may protrude from the wiring conductors 6a and 6b. Effectively prevented.

  Furthermore, as shown to Fig.4 (a), the insulating sheet 1b and resin film 2c * 2d are prepared separately. The insulating sheet 1b has the same material and size as the insulating sheet 1a described above. The resin films 2c and 2d are made of the same material as the resin film 2a described above, and have a thickness of about 10 to 30 μm.

  Next, as shown in FIG. 4B, the resin films 2b and 2c are detachably attached to the upper and lower main surfaces of the insulating sheet 1b through an adhesive layer (not shown). Next, as shown in FIG.4 (c), the several through-hole 3b is formed in the insulating sheet 1b by which resin film 2c * 2d was stuck on the upper and lower surfaces. The through-hole 3b is formed by placing the insulating sheet 1b with the resin films 2c and 2d attached on the top and bottom on a flat suction table (not shown) and irradiating laser light from the upper surface side. At this time, a ring-shaped protrusion 4b formed by melting a part of the resin film 2d at the opening of the through hole 3b is formed on the resin film 2d on the upper surface side.

  Next, as shown in FIG. 5A, the conductive paste 5b is filled into the through hole 3b that communicates the resin films 2c and 2d and the insulating sheet 11b. In order to fill the through-hole 3b with the conductor paste 5b, the same method as the above-described conductor paste 5a is used. At this time, the conductor paste 5b filled in the through hole 3b is filled up to the height of the protrusion 4b.

  Next, as shown in FIG. 5B, the resin films 2c and 2d are peeled off and removed from both main surfaces of the insulating sheet 1b. At this time, the conductor paste 5b filled in the through hole 3b is in a state of protruding from the upper and lower surfaces of the insulating sheet 1b by a height corresponding to the thickness of the resin films 2c and 2d. In addition, the conductor paste 5b protruding to the upper surface side of the insulating sheet 1b further increases the height of the protrusion 4b. Therefore, the sum of both heights of the conductor paste 5b protruding from the upper and lower surfaces of the insulating sheet 1b is larger than the sum of both heights of the conductor paste 5a protruding from the upper and lower surfaces of the insulating sheet 1a.

  Further, as shown in FIG. 6 (a), a transfer sheet 8c is prepared separately in which a wiring conductor 6c made of a metal foil such as a copper foil is detachably attached to one main surface of the support film 7c. The insulating sheet 1b filled with the conductive paste 5b is disposed on the insulating sheet 1 to which the conductors 6a and 6b are transferred. The transfer sheet 8c is formed of the same material and the same method as the transfer sheets 8a and 8b. Moreover, the insulating sheet 1b directs the one where the protrusion height of the conductor paste 5b is higher to the insulating sheet 1a side.

  Next, as shown in FIG. 6B, the insulating sheet 1b is overlaid on the insulating sheet 1a so that the wiring conductor 6b covers the end of the conductive paste 5b, and the wiring conductor 6c covers the end of the conductive paste 5b. The transfer sheet 8c is overlapped on the insulating sheet 1b so as to be covered and pressed from above and below to bring the conductor paste 5b and the wiring conductor 6b into close contact with each other and between the insulating sheet 1b, the insulating sheet 1a and the wiring conductor 6a. The wiring conductor 6c is embedded in the insulating sheet 1b. At this time, the height of the conductor paste 5b protruding from one surface of the insulating sheet 1b is increased by the height of the protrusion 4b. It is electrically connected to 6c. Further, since the conductor paste 5b is compressed by one layer of the wiring conductor 6c in addition to the height protruding from the upper and lower surfaces of the insulating sheet 1b, the amount of compression is larger than that of the conductor paste 5a. There is no. Therefore, the conductor paste 5b does not protrude from the wiring conductors 6b and 6c.

  Finally, as shown in FIG. 6 (c), after forming the laminated body by removing the support film 7c, the laminated body is heated while being pressed from above and below to insulate the insulating sheets 1a and 1b and the conductor paste 5a. The wiring board 10 is completed by thermosetting 5b. Thus, according to the method for manufacturing a wiring board of the present invention, the conductor pastes 5a and 5b are effectively prevented from protruding from the wiring conductors 6a, 6b and 6c embedded in the insulating sheets 1a and 1b. The wiring board 10 with high insulation reliability between 6b and 6c can be provided.

1a, 1b Insulating layer 3a, 3b Through hole 5a, 5b Conductive paste 6a, 6b, 6c Wiring conductor

Claims (1)

  A step of preparing first and second insulating sheets containing an uncured thermosetting resin, a step of forming a plurality of through holes in the first and second insulating sheets, and a conductor in the through holes The step of filling the paste so as to protrude from both surfaces of the first and second insulating sheets, and the transfer conductor embedding the wiring conductor made of metal foil so as to cover the conductor paste on both surfaces of the first insulating sheet And a step of transferring and embedding a wiring conductor made of a metal foil so as to cover the conductor paste on one surface of the second insulating sheet, and placing the other surface of the second insulating sheet on the first surface. In a method for manufacturing a wiring board, comprising a step of laminating on one surface of an insulating sheet and a step of curing the first and second insulating sheets and the conductive paste, the wiring sheet protrudes from both surfaces of the first insulating sheet. The sum of the heights of both of the conductor pastes is smaller than the sum of the heights of both of the conductor pastes protruding from both surfaces of the second insulating sheet. .

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