JP2015144152A - Manufacturing method of wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a wiring board which improves manufacturing efficiency.SOLUTION: In a separable metal foil 10, a first metal foil 10a larger than a region X for product formation and smaller than a support substrate 8 including the region X for product formation and a marginal region Y surrounding the region X for product formation and a second metal foil 10b larger than the first metal foil 10a are adhered separably in such a manner that an outer peripheral part of the second metal foil 10b protrudes around the first metal foil 10a. The manufacturing method of a wiring board A includes: fixing the separable metal foil 10 on a surface of the support substrate 8 while positioning the first metal foil 10a closer to the support substrate 8 in such a manner that the first metal foil 10a covers the region X for product formation and the vicinity thereof and that the outer peripheral part of the second metal foil 10b covers the marginal region Y; then forming an ID mark M in a part of the marginal region Y by means of drilling; and forming a build-up part 12 by alternately laminating a plurality of insulation layers 1 and wiring conductor layers 2 on the support substrate 8. A principal surface of the second metal foil 10b closer to the support substrate 8 is a coarse surface.

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.

  In recent years, as electronic devices typified by portable game machines and communication devices are becoming highly functional and thin, there is a thin and high-density wiring substrate called a coreless substrate as a wiring substrate used for them.

An example of such a conventional wiring board called a coreless board is shown in FIG.
In the conventional wiring board B, for example, four insulating layers 21 are laminated, and wiring conductor layers 22 are formed between the insulating layers 21 and on the upper and lower surfaces of the outermost insulating layer 21. Furthermore, a solder resist layer 23 is formed on the surfaces of the outermost insulating layer 21 and the wiring conductor layer 22.

A plurality of via holes 24 are formed in each insulating layer 21. A via conductor 25 formed integrally with the wiring conductor layer 22 is attached inside the via hole 24. The via conductor 25 establishes conduction between the wiring conductor layers 22 formed in each insulating layer 21. A part of the uppermost wiring conductor layer 22 forms a semiconductor element connection pad 26. An electrode of a semiconductor element such as a semiconductor integrated circuit element is connected to the semiconductor element connection pad 26. A part of the wiring conductor layer 22 formed in the lowermost layer forms a circuit board connection pad 27. The circuit board connection pads 27 are connected to the electrodes of the circuit board on which the wiring board B is mounted. These semiconductor element connection pads 26 and circuit board connection pads 27 are exposed in openings 23 a and 23 b provided in the solder resist layer 23.
The semiconductor element operates by transmitting an electrical signal between the semiconductor element and the circuit board via the wiring conductor layer 22.

  Next, an example of an embodiment for each process in the conventional method of manufacturing the wiring board B will be described with reference to FIGS. In the following description, the same parts as those in FIG.

First, as shown in FIG. 6A, two prepregs 28P, two separation films 29, and two separable metal foils 30 are prepared.
One main surface of the prepreg 28P serves as a product forming main surface F, and the other main surface serves as a separation main surface G. Each prepreg 28 </ b> P has a product forming region X in the center and a disposal margin region Y in the outer periphery.
The separable metal foil 30 includes a first metal foil 30a larger than the product formation region X and a second metal foil 30b larger than the first metal foil 30a. The metal foil 30b is held so as to be separable from each other via an adhesive layer (not shown) so that the outer peripheral portion of the metal foil 30b protrudes. Note that the separable metal foil 30 has a smooth surface facing each other.

  Next, as shown in FIG. 6B, two separation films 29 are stacked and sandwiched between the two prepregs 28P. Further, the separable metal foil 30 is separated in the central portion on the product formation main surface F of each prepreg 28P, and the first metal foil 30a covers the product formation region X and the vicinity thereof, and the first metal foil 30a. It arrange | positions so that the smooth surface of the outer peripheral part of the 2nd metal foil 30b which protruded may cover the surrounding allowance margin area | region Y. FIG.

  Next, what was laminated in the state of FIG.6 (b) is heated, pressing from upper and lower sides. By such pressure heating, as shown in FIG. 6C, the two support substrates 28 on which the prepreg 28P is cured are bonded to each other with the two separation films 29 sandwiched therebetween, A wiring board forming base 31 having a separable metal foil 30 fixed to the product forming main surface F of each support substrate 28 is formed. At this time, the smooth surface of the outer peripheral portion of the second metal layer 30 b that protrudes from the first metal foil 30 a is directly fixed onto the discard margin region Y of the support substrate 28.

  Next, as shown in FIG. 6D, the ID mark M is formed in the margin area Y where the smooth outer peripheral portion of the second metal foil 30b is fixed. The ID mark M is formed by drilling through holes in a predetermined arrangement in the disposal margin region Y of the support substrate 28 by drilling. The ID mark M is used for displaying and distinguishing a manufacturing lot number of a wiring board by a predetermined arrangement of through holes.

  Next, as shown in FIG. 7E, a plurality of insulating layers 21 and wiring conductor layers 22 are laminated on the upper surface of the second metal foil 30b exposed on both main surfaces of the wiring board forming base 31. At the same time, the solder resist layer 23 is deposited on the outermost insulating layer 21 and the wiring conductor layer 22 to form the build-up portion 32 for the wiring board. The wiring conductor layer 22 is formed by a known semi-additive method, for example.

  Next, as shown in FIG. 7 (f), by cutting the wiring board forming base 31 and the build-up portion 32 on the boundary between the product forming area X and the disposal margin area Y, the product forming area X The base 31 for wiring board formation and the build-up part 32 are cut out.

  Next, as shown in FIG. 7G, the wiring substrate forming base 31 on which the cut-up buildup portion 32 is formed is separated from between the separation films 29.

  Next, as shown in FIG. 8 (h), the build-up portion 32 is separated from the first metal foil 30a. Thereby, the laminated body 33 for wiring boards to which the 2nd metal foil 30b adhered to the single side | surface of the buildup part 32 is formed.

  Finally, as shown in FIG. 8 (i), after all the second metal foil 30 b is removed by etching, a solder resist layer 23 having an opening 23 b on the lowermost insulating layer 21 and wiring conductor layer 22 is formed. As a result, a conventional wiring board B as shown in FIG. 5 is formed.

  However, in the above-described method, when the through hole is drilled to form the ID mark M, both of the two due to insufficient adhesion between the smooth outer peripheral surface of the second metal foil 30b and the support substrate 28. Peeling may occur between the two. When such peeling occurs, for example, the plating solution used when forming the above-described wiring conductor layer 22 penetrates between the smooth outer peripheral surface of the second metal foil 30b and the support substrate 28 from the peeled portion. In some cases, the metal foil 30a may penetrate between the first metal foil 30a and the second metal foil 30b. As described above, when the plating chemical solution permeates, the adhesion between the support substrate 28 and the build-up portion 32 is reduced, and the build-up portion 32 in the middle of manufacture may be peeled off from the support substrate 28. For this reason, there is a problem that the yield is lowered and the wiring board cannot be manufactured efficiently.

Japanese Patent No. 4273895

  The present invention improves the adhesion between the second metal foil and the support substrate, thereby suppressing the occurrence of peeling between the two when the ID mark is formed, and the first and second metal foils from the peeled portion. The adhesion between the build-up part and the support substrate is maintained by preventing the chemical liquid from entering between. Accordingly, it is an object of the present invention to provide a method for manufacturing a wiring board with high manufacturing efficiency by preventing the build-up part from being peeled off from the support substrate and improving the manufacturing yield of the wiring board.

  The method for manufacturing a wiring board in the present invention is larger than the product formation region on the surface of the flat support substrate having a product-forming region in the center and a frame-shaped discarding region surrounding the product formation region in the outer peripheral portion. The first metal foil smaller than the support substrate and the second metal foil larger than the first metal foil are mutually connected so that the outer peripheral portion of the second metal foil protrudes around the first metal foil. The separable metal foil formed in close contact with the separable metal is covered with the first metal foil covering the product forming region and the vicinity thereof, and the outer periphery of the second metal foil protruding from the first metal foil is the surrounding disposal margin. After the first metal foil is fixed on the support substrate side so as to cover the region, an ID mark consisting of a through hole is formed by drilling in a part of the discard margin region where the second metal foil is fixed on the support substrate. Forming and separable gold A method of manufacturing a wiring board comprising a step of forming a build-up part composed of an insulating layer and a wiring conductor layer by alternately laminating and fixing a plurality of insulating layers and wiring conductor layers on a supporting board including a foil, The main surface of the second metal foil on the support substrate side is a roughened surface.

According to the method for manufacturing a wiring board of the present invention, the separable metal foil is covered with the first metal foil covering the product forming region and the vicinity thereof, and the outer peripheral portion of the second metal foil is used as the surrounding margin region. It is fixed to the support substrate side so as to cover. At this time, since the main surface on the support substrate side of the second metal foil is a roughened surface, the second metal foil is firmly fixed to the disposal margin region of the support substrate. For this reason, when forming the ID mark which consists of a through-hole by drilling in a part of discard margin area | region to which the 2nd metal foil was fixed, peeling arises between 2nd metal foil and a support substrate. Can be suppressed.
Thereby, for example, the plating solution used when forming the wiring conductor layer infiltrates between the second metal foil and the support substrate from the peeled portion, and further, the first metal foil and the second metal foil. It is possible to prevent infiltration between the metal foil. As a result, it is possible to provide a method for manufacturing a wiring board with high manufacturing efficiency, in which the adhesion between the support substrate and the buildup portion is maintained and the buildup portion is not peeled off from the support substrate.

FIG. 1 is a schematic cross-sectional view showing an example of a wiring board manufactured by the manufacturing method of the present invention. 2A to 2D are schematic cross-sectional views for explaining an example of an embodiment for each process in the method for manufacturing a wiring board of the present invention. 3E to 3G are schematic cross-sectional views for explaining an example of an embodiment for each process in the method for manufacturing a wiring board of the present invention. 4 (h) and 4 (i) are schematic cross-sectional views for explaining an example of an embodiment for each process in the method for manufacturing a wiring board of the present invention. FIG. 5 is a schematic cross-sectional view showing an example of a wiring board manufactured by a conventional manufacturing method. 6A to 6D are schematic cross-sectional views for explaining an example of an embodiment for each process in a conventional method for manufacturing a wiring board. 7E to 7G are schematic cross-sectional views for explaining an example of an embodiment for each process in a conventional method for manufacturing a wiring board. 8 (h) and 8 (i) are schematic cross-sectional views for explaining an example of an embodiment for each process in a conventional method for manufacturing a wiring board.

  First, an example of a wiring board manufactured by the method for manufacturing a wiring board of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the wiring board A manufactured by the manufacturing method of the present invention has, for example, four insulating layers 1 laminated thereon, and between the insulating layers 1 and on the upper and lower surfaces of the outermost insulating layer 1. A wiring conductor layer 2 is formed. Further, a solder resist layer 3 is formed on the surfaces of the outermost insulating layer 1 and the wiring conductor layer 2.

A plurality of via holes 4 are formed in each insulating layer 1. A via conductor 5 formed integrally with the wiring conductor layer 2 is attached inside the via hole 4. The via conductor 5 is electrically connected between the wiring conductor layers 2 formed in each insulating layer 1. A part of the uppermost wiring conductor layer 2 forms a semiconductor element connection pad 6. An electrode of a semiconductor element such as a semiconductor integrated circuit element is connected to the semiconductor element connection pad 6. A part of the wiring conductor layer 2 formed in the lowermost layer forms a circuit board connection pad 7. The circuit board connection pads 7 are connected to the electrodes of the circuit board on which the wiring board A is mounted. These semiconductor element connection pads 6 and circuit board connection pads 7 are exposed in the openings 3 a and 3 b provided in the solder resist layer 3.
The semiconductor element operates by transmitting an electrical signal between the semiconductor element and the circuit board via the wiring conductor layer 2.

  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. The same parts as those in FIG.

  First, as shown in FIG. 2A, two prepregs 8P, two separation films 9, and two separable metal foils 10 are prepared.

The prepreg 8P is for forming the support substrate 8 for supporting the wiring substrate A being manufactured while maintaining the necessary flatness when the wiring substrate A is manufactured. One main surface of the prepreg 8P is a product forming main surface F, and the other main surface is a separation main surface G. Each prepreg 8P has a product formation region X in the center and a disposal margin region Y in the outer periphery. The product formation region X is a quadrangular region, and the wiring board A is formed on the product formation region X. In this example, for the sake of simplicity, only the product forming region X corresponding to one wiring board A is shown, but in actuality, it has an area corresponding to tens to thousands of wiring boards A. . The discard margin area Y is a rectangular frame-shaped area surrounding the product forming area X.
The prepreg 8P has a thickness of about 0.1 to 0.2 mm and a substantially rectangular shape with vertical and horizontal dimensions of about 400 to 1000 mm. As the prepreg 8P, for example, a plate-like material that is made into a semi-cured state by impregnating glass fiber with a thermosetting resin such as an epoxy resin is used.

The separation film 9 is used to easily separate the two support substrates 8 inserted between the two prepregs 8P and cured from the prepregs 8P. The separation film 9 has a thickness of about 1 to 35 μm and a vertical and horizontal dimension of about 400 to 1000 mm. The vertical and horizontal dimensions of the separation film 9 are such that they protrude into the disposal margin area Y, and the vertical and horizontal dimensions are preferably about 10 to 20 mm smaller than the dimensions of the prepreg 8P.
The separation film 9 is preferably made of, for example, a metal foil such as a copper foil or a heat-resistant film such as a polyethylene terephthalate (PET) film.

The separable metal foil 10 includes a first metal foil 10a and a second metal foil 10b larger than the first metal foil 10a, and an outer peripheral portion of the second metal foil 10b around the first metal foil 10a. Are held so as to be separable from each other via an adhesive layer (not shown).
The first metal foil 10a has a thickness of about 1 to 7 μm, is larger than the product formation region X, and smaller than the second metal foil 10b. The second metal foil 10b has a thickness of about 10 to 30 μm, and has a dimension that is about 10 to 20 mm larger in length and width than the first metal foil 10a. And the support substrate 8 side main surface of the 2nd metal foil 10b is a roughening surface. The roughness of the roughened surface is preferably about ten-point average roughness Rz = about 0.5 to 2.0 μm. When Rz is smaller than 0.5 μm, the adhesion between the second metal foil 10b and the support substrate 8 becomes insufficient, and when Rz is larger than 2.0 μm, the second metal foil 10b and the first metal foil. Separation from 10a may be difficult.
For such a separable metal foil 10, first, a second metal foil 10 b is prepared, and the lower surface thereof is etched with, for example, a hydrogen peroxide solution or a ferric chloride solution. Then, after masking the outer peripheral portion of the etched lower surface, for example, a nickel-based metal layer is deposited as an adhesive layer. Furthermore, it forms by depositing the metal layer used as the 1st metal foil 10a by the plating method on the surface of a contact bonding layer, and removing masking.
The first metal foil 10a and the second metal foil 10b are preferably made of a highly conductive metal such as copper.

  Next, as shown in FIG. 2B, two separation films 9 are sandwiched between the two prepregs 8P. Further, the separable metal foil 10 is separated at the center of the product forming main surface F of each prepreg 8P, and the first metal foil 10a covers the product forming region X and the vicinity thereof, and the first metal foil 10a. It arrange | positions so that the roughening surface of the outer peripheral part of the 2nd metal foil 10b which protruded may cover the surrounding margin area Y.

Next, what was laminated in the state of FIG. 2 (b) is heated while pressing from above and below. By such pressure heating, as shown in FIG. 2C, the two support substrates 8 on which the prepreg 8P has been cured are bonded to each other with the two separation films 9 sandwiched therebetween, A wiring board forming base 11 having a separable metal foil 10 fixed to the product forming main surface F of each support substrate 8 is formed. At this time, since the thermosetting resin constituting the prepreg 8P bites into the roughened surface and is cured, the roughened surface of the outer peripheral portion of the second metal foil 10b is firmly fixed to the disposal margin region Y of the support substrate 8. Is done.
In addition, since the area | region which is not coat | covered with the separation film 9 remains in the outer peripheral part of the prepreg 8P, the two support substrates 8 are fixed by joining the prepreg 8P of this area | region. Further, in the product forming region X, the separation films 9 are not adhered to each other but are overlapped with each other.

Next, as shown in FIG. 2D, an ID mark M composed of a through hole is formed by drilling in the discard margin region Y to which the second metal foil 10b is firmly fixed.
At this time, since the ID mark M is formed in the disposal margin region Y where the second metal foil 10b is firmly fixed, peeling occurs between the second metal foil 10b and the support substrate 8. Can be suppressed.
The diameter of the through hole is about 0, 3 to 0, or 4 mm.

  Next, as shown in FIG. 3E, a plurality of insulating layers 1 and wiring conductor layers 2 are laminated on the upper surface of the second metal foil 10b exposed on both main surfaces of the wiring board forming base 11. At the same time, the solder resist layer 3 is deposited on the outermost insulating layer 1 and the wiring conductor layer 2 to form the build-up portion 12 for the wiring board.

  The insulating layer 1 is made of a thermosetting resin such as an epoxy resin or a bismaleimide triazine resin. The insulating layer 1 is formed by using a film formed by dispersing an inorganic insulating filler in an uncured product of an epoxy resin or a bismaleimide triazine resin composition, and forming the second metal on both main surfaces of the base 11 for wiring board formation. This is performed by thermocompression bonding on the foil 10b or the lower insulating layer 1 while being covered in a vacuum state. The insulating layer 1 is formed with a plurality of via holes 4 filled with via conductors 5 for electrical connection between layers, for example, by laser processing.

  The wiring conductor layer 2 is formed by depositing a conductive pattern made of electroless plating and electrolytic plating on the surface of the second metal foil 10b and the insulating layer 1 and the inner surface of the via hole 4 by, for example, a known semi-additive method. Is done. For electroless plating and electrolytic plating used by the semi-additive method, for example, a highly conductive material such as electroless copper plating and electrolytic copper plating is preferably used.

  The solder resist layer 3 is formed by, for example, applying a paste in which an inorganic filler such as silica is dispersed in an acrylic-modified epoxy resin on the outermost insulating layer 1 and the wiring conductor layer 2 by screen printing or the like, and then using a photolithography technique. It is formed by thermally curing a predetermined pattern exposed and developed. A part of the outermost wiring conductor layer 2 exposed from the solder resist layer 3 functions as a semiconductor element connection pad 6.

  Next, as shown in FIG. 3 (f), by cutting the wiring board forming base 11 and the buildup portion 12 on the boundary between the product forming area X and the disposal margin area Y, the product forming area X The wiring board formation base 11 and the build-up part 12 are cut out. For the cutting, for example, a dicing apparatus may be used.

  Next, as shown in FIG. 3G, the wiring board forming base 11 on which the cut-up buildup part 12 is formed is separated from between the separation films 9. In this separation, since the separation films 9 are in close contact with each other by pressure heating, they can be easily separated.

  Next, as shown in FIG.4 (h), the buildup part 12 is isolate | separated from the 1st metal foil 10a. Thereby, the laminated body 13 for the wiring board A in which the second metal foil 10b is fixed to the lower surface of the buildup portion 12 is formed. At the time of the separation, the second metal foil 10b is only separably held on the first metal foil 10a through the adhesive layer, so that the first metal foil 10a and the second metal foil 10b are separated. It is possible to easily separate the laminated body 13 without damaging the laminated body 13 simply by peeling them.

  Finally, as shown in FIG. 4 (i), after all the second metal foil 10b is removed by etching, a solder resist layer 3 having an opening 3b on the lowermost insulating layer 1 and wiring conductor layer 2 is formed. As a result, a wiring board A as shown in FIG. 1 is formed.

By the way, according to the method for manufacturing a wiring board of the present invention, the separable metal foil 10 is covered with the first metal foil 10a covering the product forming region X and the vicinity thereof, and the outer peripheral portion of the second metal foil 10b. It is fixed to the support substrate 8 so as to cover the surrounding margin area Y. At this time, since the main surface of the second metal foil 10 b on the side of the support substrate 8 is a roughened surface, the second metal foil 10 b is firmly fixed to the disposal margin region Y of the support substrate 8. For this reason, when forming the ID mark M which consists of a through-hole by drilling in a part of the discard margin area Y to which the second metal foil 10b is firmly fixed, the second metal foil 10b and the support substrate 8 It can suppress that peeling arises between.
Thereby, for example, the plating solution used when forming the wiring conductor layer 2 infiltrates between the second metal foil 10b and the support substrate 8 from the peeled portion, and further, the first metal foil 10a. And the second metal foil 10b can be prevented from entering. As a result, it is possible to provide a method for manufacturing a wiring board with high manufacturing efficiency in which the adhesion between the support substrate 8 and the buildup portion 12 is maintained and the buildup portion 12 is not peeled off from the support substrate 8.

DESCRIPTION OF SYMBOLS 1 Insulation layer 2 Wiring conductor layer 8 Support substrate 10 Separable metal foil 10a 1st metal foil 10b 2nd metal foil 12 Build-up part A Wiring board M ID mark X Product formation area Y Waste allowance area

Claims (1)

  A plate-like support substrate surface having a product formation region in the center and a frame-shaped disposal margin region surrounding the product formation region in the outer peripheral portion is larger than the product formation region and smaller than the support substrate. 1 metal foil and a second metal foil larger than the first metal foil are in close contact with each other so that the outer periphery of the second metal foil protrudes around the first metal foil In the separable metal foil, the first metal foil covers the product forming region and the vicinity thereof, and the outer peripheral portion of the second metal foil protruding from the first metal foil is disposed around the surroundings. After the first metal foil is fixed to the support substrate so as to cover the margin area, a part of the discard margin area where the second metal foil is adhered to the support substrate is drilled. Shape ID mark consisting of through holes And a step of forming a build-up portion composed of the insulating layer and the wiring conductor layer by alternately laminating and fixing a plurality of insulating layers and wiring conductor layers on the support substrate including the separable metal foil. A method for manufacturing a wiring board comprising the second metal foil, wherein the supporting board side main surface of the second metal foil is a roughened surface.

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