JP2010262954A - Method for manufacturing wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a highly reliable wiring board of high density wiring, which includes a wiring conductor where a via hole and a groove, which are installed in an insulating layer, are filed with plated metallic layers with a simple structure and a simple method. <P>SOLUTION: An upper insulating layer 3 formed of an insulating layer of one layer is laminated on a lower insulating layer 1 where a lower wiring conductor 2 is formed. The via hole 4 where the wiring conductor 2 is set to be a base is formed in the insulating layer 3 by laser beam machining. The groove 6 for forming upper wiring conductor is formed on the surface of the insulating layer 3 by laser beam machining or wet blasting. The plated metallic layer 7 is bonded onto the insulating layer 3 so that the via hole 4 and the groove 6 may be filled with the layer 7. The plated metallic layer 7 is removed from the insulating layer 3 so that the plated metallic layer may be left in the via hole 4 and the groove 6 as it is while they are filled with the layer 7. The upper wiring conductor 8 formed of the plated metallic layer is formed in the via hole 4 and the groove 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a wiring board.

  Conventionally, a core substrate having wiring conductors made of copper foil on both surfaces of a glass-resin plate having a thickness of about 0.2 to 2.0 mm as a high-density multilayer wiring substrate used for mounting electronic components such as semiconductor elements There is known a build-up wiring board in which insulating layers made of a resin having a thickness of about 10 to 100 μm and wiring conductors made of a plating conductor layer are alternately laminated on both surfaces. Such a build-up wiring board is manufactured, for example, by the method described below.

  First, an insulating sheet in which a glass cloth is impregnated with a thermosetting resin such as an epoxy resin or a bismaleimide triazine resin is prepared. Next, copper foil is stuck on both sides of the insulating sheet, and the thermosetting resin in the insulating sheet is thermoset to obtain a double-sided copper-clad plate. Next, a through-hole penetrating the upper and lower surfaces of the double-sided copper-clad plate is drilled, and a plated conductor layer is deposited on the inner wall of the through-hole to electrically connect the upper and lower copper foils with the plated conductor layer in the through-hole. Connecting. Next, after filling the through hole with resin, the upper and lower copper foils are etched into a predetermined pattern to obtain a core substrate having wiring conductors made of copper foil on both surfaces of the glass-resin plate.

  Next, a resin film in which an inorganic insulating filler is dispersed in a thermosetting resin such as epoxy resin or bismaleimide triazine resin is attached to the upper and lower surfaces of the core substrate, and the thermosetting resin in the resin film is thermoset. To form an insulating layer. Next, via holes are drilled in the insulating layer by laser processing, and wiring conductors made of plated conductor layers are simultaneously formed on the surface of the insulating layer including the inside of the via holes by a semi-additive method. Further, by forming the insulating layer and the wiring conductor of the next layer a plurality of times, the insulating substrate made of resin and the plated conductor layer are formed on both surfaces of the core substrate having the wiring conductor made of copper foil on both surfaces of the glass-resin plate. A build-up wiring board formed by alternately laminating wiring conductors is manufactured.

  However, since such a build-up wiring board forms the wiring conductor in a state of protruding from the surface of each insulating layer, the closer the wiring conductor width and the distance between the wirings, the closer the wiring conductor and the insulating layer are. Since the area is reduced, there is a problem that the adhesion of the wiring conductor to the insulating layer is weakened. In order to solve the problem, a wiring conductor forming groove is formed on the surface of the insulating layer in which the via hole is formed, and a plated metal layer filling the via hole and the groove is covered on the surface of the insulating layer. After that, by removing the plating metal layer from the insulating layer so that the plating metal layer remains filled in the via hole and groove, the plating metal layer remaining in the via hole and groove is removed. This is a method of forming a wiring conductor. According to this method, since the side surface of the wiring conductor made of the plated metal layer filled in the groove is also in close contact with the insulating layer, the close contact with the insulating layer is strengthened.

  In such a method, in order to form a via hole and a groove for forming a wiring conductor in the insulating layer, for example, the insulating layer for forming the via hole and the groove has a two-layer structure, and a photo process or the like is performed on the first insulating layer. A via hole is formed by laser processing, dry etching or the like, and then a second insulating layer is stacked thereon, and the second insulating layer is partially etched to form a first layer. A method of forming a groove having an insulating layer as a bottom surface is employed. In this case, since two insulating layers are required for forming the via hole and the groove, the structure of the wiring board becomes complicated and the manufacturing method becomes complicated. On the other hand, a method has been proposed in which an insulating layer for forming a via hole and a groove is composed of a single layer, and the via hole and the groove are formed using separate photolithography and etching. According to this method, since the insulating layer for forming the via hole and the groove is composed of one layer, the structure of the wiring board is not complicated. However, the mask for forming the via hole and the mask for forming the groove need to be separately formed and peeled, and the etching for forming the groove is half etching by controlling the etching time. The control becomes severe and the manufacturing method is complicated.

JP 2002-246744 A JP 2003-183127 A

  The present invention has been devised in view of such conventional problems, and its problem is to provide a highly reliable and highly reliable wiring conductor having a plated metal layer filled in a via hole and a groove provided in an insulating layer. An object of the present invention is to provide a method of manufacturing a wiring board of density wiring with a simple structure and a simple method.

The method for manufacturing a wiring board according to the present invention includes a step of laminating an upper insulating layer made of one insulating layer on a lower insulating layer having a lower wiring conductor formed on the surface, and A step of forming a via hole having a lower wiring conductor as a bottom by laser processing; a step of forming a groove for forming an upper wiring conductor on the surface of the upper insulating layer by laser processing or wet blasting; and the via hole and Depositing a plating metal layer on the upper insulating layer so as to fill the groove, and leaving the plating metal layer filled in the via hole and in the groove with the plating metal layer filled Removing from the upper insulating layer, and forming an upper wiring conductor made of the plated metal layer in the via hole and in the groove. .
The method for manufacturing a wiring board according to the present invention includes a step of laminating an upper insulating layer composed of one insulating layer on a lower insulating layer having a lower wiring conductor formed on the surface, and the upper insulating layer. Forming a groove for forming an upper wiring conductor on the surface by laser processing or wet blasting; forming a via hole having the lower wiring conductor as a bottom surface in the upper insulating layer by laser processing; and the via hole And a step of depositing a plating metal layer on the upper insulating layer so as to fill the groove, and leaving the plating metal layer filled with the plating metal layer in the via hole and in the groove And removing the upper insulating layer from the upper insulating layer to form an upper wiring conductor made of the plated metal layer in the via hole and in the groove. A.

  According to the method for manufacturing a wiring board of the present invention, since the insulating layer for forming the via hole and the groove is formed of one insulating layer, the structure of the wiring board can be simplified. In addition, since the via hole formed in the insulating layer is formed by laser processing, a mask is not required for forming the via hole, and only the mask for forming the groove may be formed and removed. . In addition, by adopting laser processing or wet blast processing when forming the groove, the groove having a predetermined width and depth is accurately formed without requiring severe control as compared with the case of forming the groove by etching. be able to. Further, when the groove is formed by wet blasting after forming the via hole, the inside of the via hole and the groove can be uniformly roughened by wet blasting so that the plated metal layer can be firmly attached in the via hole and in the groove.

(A)-(d) is a schematic sectional drawing for every process for demonstrating an example of embodiment in the manufacturing method of the wiring board of this invention. (E)-(g) is a schematic sectional drawing for every process for demonstrating an example of embodiment in the manufacturing method of the wiring board of this invention. (B)-(d) is a schematic sectional drawing for every process for demonstrating the other example of embodiment in the manufacturing method of this invention. (E)-(f) is a schematic sectional drawing for every process for demonstrating the further another example of embodiment in the manufacturing method of this invention.

  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 the accompanying drawings. First, as shown in FIG. 1A, a lower wiring conductor 2 is formed on the surface of a core substrate 1 serving as a lower insulating layer, and an upper insulating layer 3 is laminated thereon. For example, a double-sided copper-clad laminate is used as the core substrate 1 and the wiring conductor 2 is formed by a subtractive method or a semi-additive method. The insulating layer 3 is an uncured thermosetting resin film or glass cloth having a thickness of about 10 to 100 μm in which an inorganic insulating filler is dispersed in an uncured material of a thermosetting resin such as an epoxy resin or a bismaleimide triazine resin. A prepreg impregnated with a conductive resin is used.

  Next, as shown in FIG. 1B, a via hole 4 having a part of the wiring conductor 2 as a bottom surface is formed in the insulating layer 3 by laser processing. The laser processing is performed by irradiating a pulse of a laser beam having a diameter corresponding to the diameter of the via hole 4 by scanning with a galvano mirror at least one pulse at the formation position of each via hole 4 in the insulating layer 3. In this case, since a laser beam is scanned with a galvano mirror to irradiate the formation position of each via hole 4 in the insulating layer 3, no mask is required for the formation of the via hole. As the laser, a carbon dioxide laser or a YAG laser is used.

  Next, as shown in FIG. 1C, a mask 5 having an opening corresponding to the position of a wiring conductor forming groove 6 to be described later is formed on the insulating layer 3 in which the via hole is formed. The mask 5 is formed by sticking a photosensitive resin film on the insulating layer 3 and subjecting the resin film to exposure / development processing using a photolithography technique. Alternatively, it is formed by depositing a metal layer such as chromium on the insulating layer 3 and etching the metal layer into a predetermined pattern by a photolithography technique.

  Next, as shown in FIG. 1D, the insulating layer 3 exposed from the opening of the mask 5 is subjected to laser processing using an excimer laser or wet blast processing using alumina abrasive grains to thereby form the wiring conductor forming groove 6. Form. In this case, the groove 6 having a predetermined width and depth can be accurately formed without requiring severe control as compared with etching. Further, when the groove 6 is formed by wet blasting, the inside of the via hole 4 and the inside of the groove 6 can be uniformly roughened by wet blasting, and a plated metal layer 7 described later is covered in the via hole 4 and the groove 6. In the case of deposition, the plated metal layer 7 can be firmly adhered in the via hole 4 and the groove 6. In the case of employing a YAG laser instead of an excimer laser for laser processing for forming the groove 6, the mask 5 is not necessarily required, but when forming the groove 6 including a solid pattern or a pattern having a large area such as a pad. It is preferable to use an excimer laser with a short processing time for forming the groove 6.

  Next, as shown in FIG. 2E, the mask 5 on the insulating layer 3 is removed. If the mask 5 is formed from a resin film, the mask 5 may be removed by peeling the mask 5 using a commercially available resist stripping solution. If the mask 5 is formed from a metal layer, it may be removed by etching.

  Next, as shown in FIG. 2F, a plated metal layer 7 is deposited on the surface of the insulating layer 3 so as to fill the via hole 4 and the groove 6. The plated metal layer 7 is formed by, for example, electroless copper plating and electrolytic copper plating. Specifically, first, the surface of the insulating layer 3 including the inside of the via hole 4 and the inside of the groove 6 is roughened as necessary, and then a palladium catalyst is applied to the surface. It is formed by depositing to a thickness of about 2.0 μm and then depositing electrolytic copper plating on the surface of the electroless copper plating so as to have a thickness of about 5 to 30 μm from the surface of the insulating layer 3.

  Next, as shown in FIG. 2G, the plated metal layer 7 is removed from the surface of the insulating layer 3 so that the plated metal layer 7 remains filled in the via hole 4 and the groove 6, thereby forming the via hole. An upper wiring conductor 8 made of a plated metal layer 7 is formed in 4 and in the groove 6. The plating metal layer 7 may be removed from the surface of the insulating layer 3 by, for example, a combination of mechanical polishing and chemical etching. Specifically, the mechanical polishing is performed up to several μm from the surface of the insulating layer 3. The thickness of the plated metal layer 7 is reduced and the surface of the plated metal layer 7 is flattened, and then chemical etching is performed to such an extent that the plated metal layer does not remain on the surface of the insulating layer 3. At this time, if etching is performed until the surface of the plated metal layer 7 in the via hole 4 and the groove 6 is recessed by about 0.5 to 2 μm from the surface of the insulating layer 3, the plating metal layer 3 remaining on the surface of the insulating layer 3 is removed. Residues can be completely removed, thereby reducing the occurrence of electrical leakage or migration problems between the wiring conductors 8.

  Thus, according to the method for manufacturing a wiring board of the present invention, a highly reliable high-density wiring board having a wiring conductor formed by filling a plated metal layer in via holes and grooves provided in an insulating layer has a simple structure. And it can manufacture efficiently by a simple method. It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention. For example, in the example of the above-described embodiment, the groove 6 is provided on the surface of the insulating layer 3 after the via hole 4 is provided in the insulating layer 3. However, after the step described with reference to FIG. As shown in FIG. 3, a mask 5 is formed on the insulating layer 3, and then, as shown in FIG. 3C, a groove 6 for forming a wiring conductor is formed in the insulating layer 3 by laser processing or wet blast processing. Thereafter, as shown in FIG. 3D, the via hole 4 may be formed by laser processing, and then the steps described in FIGS. 2E to 2F may be performed. In the example of the embodiment described above, the groove 6 is formed in the insulating layer 3, the mask 5 is removed, and then the plated metal layer 7 is deposited on the surface of the insulating layer 3. After the process described in d), as shown in FIG. 4E, the plated metal layer 7 is deposited so as to fill the via hole 4 and the groove 6 with the mask 5 remaining. Next, as shown in FIG. 4F, the plated metal layer 7 and the mask 5 may be mechanically polished and removed, and then chemically etched. In this case, the labor for removing the mask 5 can be saved and the palladium catalyst for the electroless copper plating for the electroless copper plating does not remain on the surface of the insulating layer 3, so that the electrical insulation reliability between the wiring conductors 8 can be achieved. The property can be made extremely high.

1 Core substrate (lower insulating layer)
2 Lower wiring conductor layer 3 Upper insulating layer 4 Via hole 5 Mask 6 Groove 7 Plating metal layer 8 Upper wiring conductor

Claims (2)

  A step of laminating an upper insulating layer composed of one insulating layer on a lower insulating layer having a lower wiring conductor formed on the surface; and a via hole having the lower wiring conductor as a bottom surface in the upper insulating layer. A step of forming by laser processing, a step of forming a groove for forming an upper wiring conductor on the surface of the upper insulating layer by laser processing or wet blasting, and the upper layer so as to fill the via hole and the groove. A step of depositing a plating metal layer on the insulating layer, and removing the plating metal layer from the upper insulating layer so that the plating metal layer remains filled in the via hole and the groove, Forming an upper wiring conductor made of the plated metal layer in the via hole and in the groove.   A step of laminating an upper insulating layer composed of one insulating layer on a lower insulating layer having a lower wiring conductor formed on the surface; and a groove for forming an upper wiring conductor on the surface of the upper insulating layer. A step of forming by laser processing or wet blasting; a step of forming a via hole in the upper insulating layer by using the lower wiring conductor as a bottom surface; and the upper layer so as to fill the via hole and the groove. A step of depositing a plating metal layer on the insulating layer, and removing the plating metal layer from the upper insulating layer so that the plating metal layer remains filled in the via hole and the groove, Forming an upper wiring conductor made of the plated metal layer in the via hole and in the groove.

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