JP2016181585A - Wiring board manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board manufacturing method which allows a semiconductor element to be stably activated.SOLUTION: A wiring board manufacturing method comprises the steps of: forming on a surface of a metal foil 10b soluble in a first etchant, a barrier metal layer 11 composed of a first metal layer 11a insoluble in the first etchant and a second metal layer 11b soluble in the first etchant and a third metal layer insoluble in the first etchant, and subsequently laminating on the barrier metal layer 11, a wiring conductor layer 2 soluble in the first etchant and an insulation layer 1 to form a build-up portion 12 thereby to form a laminate 13 composed of the metal foil 10b, the barrier metal layer 11 and the build-up portion 12; subsequently removing the metal foil 10b by etching with the first etchant; subsequently removing the first metal layer 11a by etching with a second etchant in which the second metal layer 11b and the wiring conductor layer 2 are insoluble; removing the second metal layer 11b by etching with the first etchant; and removing the third metal layer 11c by etching with the second etchant.SELECTED DRAWING: Figure 5

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 manufacturing method of the conventional 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. 7A, a prepreg 28P, two adhesive films 29, and two separable metal foils 30 are prepared.
The prepreg 28 </ b> P has a product forming region X in the center and a discard margin region Y in the outer periphery.
The separable metal foil 30 is obtained by holding a first metal foil 30a and a second metal foil 30b with a small adhesive force so as to be separable from each other via an adhesive layer (not shown). The thickness of the first metal foil 30a is about 15 to 20 μm. The thickness of the second metal foil 30b is about 5 to 10 μm. The separable metal foil 30 is made of, for example, copper soluble in a first etching solution such as sulfuric acid / hydrogen peroxide.

  Next, as shown in FIG.7 (b), the separable metal foil 30 is arrange | positioned through the adhesive film 29 in the center part of the prepreg 28P upper and lower surfaces with the 1st metal foil 30a facing the prepreg 28P.

  Next, what was laminated in the state of FIG. 7B is heated while being pressed from above and below. By such pressure heating, as shown in FIG. 7C, the support substrate 28 having the separable metal foil 30 fixed to the upper and lower surfaces of the cured prepreg 28P is formed.

  Next, as shown in FIG. 7D, barrier metal layers 31 are formed on both main surfaces of the support substrate 28 including the separable metal foil 30. The thickness of the barrier metal layer 31 is 0.5 μm or less. The barrier metal layer 31 is made of chromium, for example. Chromium is insoluble in the first etching solution described above and is soluble in the second etching solution such as a perchloric acid solution.

  Next, as shown in FIG. 8E, a plurality of insulating layers 21 and wiring conductor layers 22 are laminated on both main surfaces of the support substrate 28 on which the barrier metal layer 31 is formed, and the outermost layer is formed. A build-up portion 32 for a wiring board is formed by depositing a solder resist layer 23 having an opening 23b on the insulating layer 21 and the wiring conductor layer 22. The wiring conductor 22 is made of a material that is soluble in the first etching solution and insoluble in the second etching solution.

  Next, as shown in FIG. 8 (f), the support substrate 28, the barrier metal layer 31, and the buildup portion 32 are cut on the boundary between the product formation region X and the disposal margin region Y, thereby forming the product. The support substrate 28, the barrier metal layer 31, and the buildup portion 32 in the region X are cut out.

  Next, as shown in FIG. 8G, the barrier metal layer 31 and the buildup portion 32 are separated from the first metal foil 30a. As a result, a laminated body 33 for the wiring board in which the second metal foil 30b is fixed to one surface of the barrier metal layer 31 is formed.

  Next, as shown in FIG. 9H, the second metal foil 30b made of, for example, copper is completely removed by etching with the first etching solution. At this time, the barrier metal layer 31 made of, for example, chromium is not dissolved in the first etching solution. The barrier metal layer 31 prevents the uppermost wiring conductor layer 22 from being eroded by the first etching solution.

  Next, as shown in FIG. 9I, the barrier metal layer 31 is removed by etching with a second etching solution. At this time, since the wiring conductor 22 is insoluble in the second etchant, it remains in the build-up portion 32 without being etched.

  Finally, as shown in FIG. 9 (j), a conventional solder resist layer 23 having an opening 23a is formed on the surfaces of the uppermost insulating layer 21 and wiring conductor layer 22, so that the conventional structure shown in FIG. A wiring board B is formed.

However, in the above-described method, since the thickness of the second metal foil 30b is 5 to 10 μm, it is necessary to perform a long-time etching process in order to remove the second metal foil 30b by etching.
However, a minute pinhole may exist in the barrier metal layer 31 in some cases. In this case, the first etching solution for etching the second metal foil 30b reaches the wiring conductor layer 22 through the pinhole. As a result, the wiring conductor layer 22 soluble in the first etching solution may be eroded by the first etching solution and disconnected. For this reason, there is a problem that an electrical signal cannot be transmitted satisfactorily through the wiring conductor layer 22 and the semiconductor element does not operate stably.

JP 2007-335698 A

  The present invention prevents the wiring conductor layer from being disconnected by avoiding the wiring conductor layer from being exposed to the etching solution for a long time. Accordingly, it is an object of the present invention to provide a method for manufacturing a wiring board in which an electric signal can be satisfactorily transmitted through a wiring conductor layer and a semiconductor element can be stably operated.

  The method for manufacturing a wiring board according to the present invention includes a step of preparing a support substrate in which a metal foil having a thickness of 5 to 10 μm that is soluble in a first etching solution is adhered to the surface, and a first etching on the surface of the metal foil. A first metal layer insoluble in the liquid, a second metal layer having a thickness of 0.1 to 0.5 μm soluble in the first etching liquid, and a third metal layer insoluble in the first etching liquid. A step of forming a barrier metal layer formed by sequential deposition, and a wiring conductor layer formed by alternately laminating a wiring conductor layer made of a metal soluble in the first etching solution and an insulating layer on the surface of the barrier metal layer And a step of forming a build-up portion composed of an insulating layer, a step of separating a laminate comprising a metal foil and a barrier metal layer and a build-up portion from a support substrate, and a metal foil in the laminate using a first etching solution After etching and removing the first gold The metal layer is etched away with a second etchant insoluble in the second metal layer and the wiring conductor layer, then the second metal layer is etched away with the first etchant, and finally the third metal And a step of making the build-up portion independent by etching away the layer using a second etching solution.

According to the method for manufacturing a wiring board of the present invention, the barrier metal layer interposed between the metal foil and the buildup portion is insoluble in the first etching solution and soluble in the second etching solution. Since the second metal layer having a thickness of 0.1 to 0.5 μm sandwiched between the three metal layers and soluble in the first etching solution but insoluble in the second etching solution is sandwiched, the metal foil is When the first metal layer is etched away with the first etchant, even if there is a pinhole in the first metal layer, the second metal layer is partially etched immediately below the pinhole, but the first etchant is applied to the wiring conductor layer. Reaching can be prevented by the third metal layer.
Furthermore, when the second metal layer is etched away using the first etching solution after the first metal layer is removed by etching, the thickness of the second metal layer is extremely thin, 0.1 to 0.5 μm. A short etching process may be performed. Therefore, even if there is a pinhole in the third metal layer, the first etching liquid can be suppressed from greatly etching the wiring conductor layer.
As a result, the wiring conductor layer is prevented from being disconnected by etching of the metal foil or the barrier metal layer, and the electrical signal is satisfactorily transmitted through the wiring conductor layer so that the semiconductor element can stably operate. A manufacturing method can be provided.

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. FIGS. 5J to 5N are schematic cross-sectional views for explaining an example of the embodiment for each process in the method for manufacturing a wiring board of the present invention. FIG. 6 is a schematic cross-sectional view showing an example of a wiring board manufactured by a conventional manufacturing method. 7A to 7D are schematic cross-sectional views for explaining an example of an embodiment for each process in a conventional method for manufacturing a wiring board. 8E to 8G are schematic cross-sectional views for explaining an example of an embodiment for each process in the conventional method for manufacturing a wiring board. 9 (h) to 9 (j) are schematic cross-sectional views for explaining an example of the embodiment for each process in the 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. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  First, as shown in FIG. 2A, a prepreg 8P, two adhesive 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.
The prepreg 8P has a product forming region X in the center and a discard 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 adhesive film 9 is interposed between the prepreg 8P and the separable metal foil 10, and adheres the cured prepreg 8P and separable metal foil 10.
The adhesive film 9 has a thickness of about 25 to 50 μm and a vertical and horizontal dimension of about 400 to 1000 mm.
The adhesive film 9 is preferably made of a heat-resistant film such as an epoxy resin or a polyimide resin.

The separable metal foil 10 is obtained by holding a first metal foil 10a and a second metal foil 10b with a small adhesive force so as to be separable from each other via an adhesive layer (not shown).
The first metal foil 10a has a thickness of about 15 to 20 μm, and is larger than the product forming region X and smaller than the second metal foil 10b. The second metal foil 10b has a thickness of about 5 to 10 [mu] m, and has dimensions smaller by about 5 mm in length and width than the prepreg 8P.
The separable metal foil 10 is made of copper or the like that is soluble in a first etching solution such as sulfuric acid / hydrogen peroxide.
The adhesive layer is preferably made of, for example, a heat-resistant adhesive such as silicon resin or acrylic resin, or a nickel metal layer in order to withstand the heat load applied during the formation of the wiring board A. When such an adhesive layer separates the buildup portion 12 described later from the support substrate 8, the first metal foil 10 a and the second metal foil 10 b are separated from each other without being peeled off. It is preferable that the adhesive force is a small adhesive force of about 1 to 10 N / m.

  Next, as shown in FIG.2 (b), the separable metal foil 10 is arrange | positioned through the adhesive film 9 in the center part of the upper and lower surfaces of the prepreg 8P with the 1st metal foil 10a facing the prepreg 8P.

  Next, what was laminated in the state of FIG. 2 (b) is heated while pressing from above and below. By such pressurization and heating, as shown in FIG. 2C, the support substrate 8 having the separable metal foil 10 fixed to the upper and lower surfaces of the cured prepreg 8P is formed.

  Next, as shown in FIG. 2D, the first metal layer 11 a is formed on both main surfaces of the support substrate 8 including the separable metal foil 10. The thickness of the 1st metal layer 11a is about 0.01-0.1 micrometer, for example, is formed by the well-known sputtering method. The first metal layer 11a is made of, for example, chromium that is insoluble in the first etching solution and soluble in the second etching solution such as a perchloric acid solution.

  Next, as shown in FIG. 3E, a second metal layer 11b is formed on the surface of the first metal layer 11a. The thickness of the 2nd metal layer 11b is about 0.1-0.5 micrometer, for example, is formed by the well-known sputtering method. The second metal layer 11b is made of copper or the like that is insoluble in the second etching solution and soluble in the first etching solution.

Next, as shown in FIG. 3F, a third metal layer 11c is formed on the surface of the second metal layer 11b. Thereby, the barrier metal layer 11 including the first metal layer 11a, the second metal layer 11b, and the third metal layer 11c is formed.
The thickness of the third metal layer 11c is about 0.01 to 0.1 μm, and is formed by, for example, a well-known sputtering method. Similar to the first metal layer 11a, the third metal layer 11c is made of, for example, chromium that is insoluble in the first etching solution and soluble in the second etching solution.

  Next, as shown in FIG. 3G, a plurality of wiring conductor layers 2 and insulating layers 1 are laminated on the surface of the barrier metal layer 11, and on the outermost wiring conductor layers 2 and insulating layers 1. By depositing the solder resist layer 3 having the opening 3b, the build-up portion 12 for the wiring board is formed.

  The wiring conductor layer 2 is formed by depositing a conductive pattern made of electroless plating and electrolytic plating on the surface of the barrier metal layer 11 by, for example, a known semi-additive method. For electroless plating and electrolytic plating used by the semi-additive method, a highly conductive material such as electroless copper plating and electrolytic copper plating that is soluble in the first etching solution is preferably used.

  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 forming a film formed by dispersing an inorganic insulating filler in an uncured product of an epoxy resin or a bismaleimide triazine resin composition, the surface of the barrier metal layer 11 on both main surfaces of the support substrate 8, and the lower layer. This is performed by thermocompression bonding to the surface of the insulating layer 1 in a state of being coated 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 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 circuit board connection pad 7.

Next, as shown in FIG. 4 (h), the support substrate 8, the barrier metal layer 11, and the buildup portion 12 are cut at the boundary between the product formation region X and the disposal margin region Y, thereby forming the product. The support substrate 8, the barrier metal layer 11, and the buildup portion 12 in the region X are cut out.
For the cutting, for example, a dicing apparatus may be used.

Next, as shown in FIG. 4I, the barrier metal layer 11 and the buildup portion 12 are separated from the first metal foil 10a. Thereby, the laminated body 13 for wiring boards in which the second metal foil 10b is fixed to one surface of the barrier metal layer 11 is formed.
In this separation, the second metal foil 10b is held on the first metal foil 10a with a small adhesion force so as to be separable via the adhesive layer. It is possible to easily separate the laminated body 13 without damaging it by simply peeling it off from the metal foil 10b.

Next, as shown in FIG. 5J, the second metal foil 10b made of, for example, copper is completely removed by etching with the first etching solution.
At this time, since the thickness of the second metal foil 10b is as large as 5 to 10 μm, it is necessary to perform an etching process for a long time with the first etching solution. At this time, even if there is a pinhole in the first metal layer 11a, the second metal layer 11b is partially etched immediately below the pinhole, but the first etching solution reaches the wiring conductor layer 2. Is prevented by the third metal layer 11c.

Next, as shown in FIG. 5K, the first metal layer 11a is removed by etching with a second etching solution.
At this time, the second metal layer 11b and the wiring conductor layer 2 that are insoluble in the second etching solution are never etched.

Next, as shown in FIG. 5L, the second metal layer 11b is removed by etching with the first etchant.
In addition, since the thickness of the 2nd metal layer 11b is as small as about 0.1-0.5 micrometer, the etching time by a 1st etching liquid may be short.
Therefore, even if there is a pinhole in the third metal layer 11c, the wiring conductor layer 2 is not greatly etched.

Next, as shown in FIG. 5M, the third metal layer 11c made of, for example, chromium is removed by etching with a second etching solution.
At this time, the wiring conductor layer 2 insoluble in the second etching solution is not dissolved.

  Finally, as shown in FIG. 5 (n), by forming a solder resist layer 3 having an opening 3a on the uppermost insulating layer 1 and wiring conductor layer 2, a wiring board A as shown in FIG. Is formed.

  As described above, according to the method for manufacturing a wiring board of the present invention, there is a pinhole in the first to third metal layers constituting the barrier metal layer 11 when the metal foil 10 and the barrier metal layer 11 are etched. Even if it does, the wiring conductor layer 2 is not greatly etched. Therefore, it is possible to effectively prevent disconnection from occurring in the wiring conductor layer 2. As a result, it is possible to provide a method for manufacturing a wiring board in which a semiconductor element can operate stably by transmitting an electric signal through the wiring conductor layer 2 satisfactorily.

  In addition, this invention is not limited to an example of above-mentioned embodiment, A various change is possible if it is a range which does not deviate from the summary of this invention. For example, in the above-described embodiment, the first and third metal layers are made of chromium. However, in addition to chromium, for example, a single metal such as titanium or nickel or an alloy of these metals may be used. Absent.

DESCRIPTION OF SYMBOLS 1 Insulation layer 2 Wiring conductor layer 8 Support board | substrate 10b (2nd) metal foil 11 Barrier metal layer 11a 1st metal layer 11b 2nd metal layer 11c 3rd metal layer 12 Buildup part 13 Laminated body A Wiring board

Claims (1)

A step of preparing a support substrate in which a metal foil having a thickness of 5 to 10 μm which is soluble in the first etching solution is in close contact with the surface;
On the surface of the metal foil, a first metal layer insoluble in the first etching solution, a second metal layer having a thickness soluble in the first etching solution of 0.1 to 0.5 μm, and the first Forming a barrier metal layer formed by sequentially depositing a third metal layer insoluble in one etching solution;
On the surface of the barrier metal layer, a wiring conductor layer made of a metal soluble in the first etching solution and an insulating layer are alternately laminated to form a build-up portion made of the wiring conductor layer and the insulating layer. Process,
Separating the laminate comprising the metal foil and the barrier metal layer and the build-up portion from the support substrate;
After the metal foil in the laminate is removed by etching using the first etching solution, the first metal layer is etched using a second etching solution in which the second metal layer and the wiring conductor layer are insoluble. Removing the second metal layer using the first etchant, and finally removing the third metal layer using the second etchant to remove the build-up portion. A method for manufacturing a wiring board, comprising the steps of:

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