JP2016219762A - Wiring board and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board having an excellent electric connection between a semiconductor element connection pad embedded in an insulation resin layer and an electrode terminal of a semiconductor element, and a manufacturing method thereof.SOLUTION: A wiring board 10 comprises: an insulation base 1 onto which a plurality of insulation resin layers 1a to 1d are vertically laminated; a semiconductor element connection pad 4 which is embedded into an upper surface side of the insulation resin layer 1a of the uppermost layer, and is formed by plating conductor layers 4a and 4b of which a contact surface connected to an electrode terminal T of a semiconductor element S is projected from the upper surface of insulation resin layer 1a; and an external part connection pad 5 which is deposed to a lower surface of the insulation base 1, and electrically connected to the semiconductor element connection pad 4 through a wiring conductor 2 provided in an inner part of the insulation base 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wiring board used for mounting a semiconductor element and a manufacturing method thereof.

  FIG. 4 shows an example of a conventional wiring board 20 on which the semiconductor element S is mounted. A conventional wiring board 20 includes an insulating base 11 and a wiring conductor 12. The insulating base 11 is formed by laminating a plurality of insulating resin layers 11a to 11d. A via hole 13 is formed in each of the insulating resin layers 11a to 11b. The wiring conductor 12 is formed in the surface of the insulating resin layers 11 a to 11 d and the via hole 13. Thereby, the upper and lower wiring conductors 12 are electrically connected via the via hole 13. A large number of semiconductor element connection pads 14 are formed on the upper surface of the insulating substrate 11. A large number of external connection pads 15 are formed on the lower surface of the insulating substrate 11. The semiconductor element connection pad 14 and the external connection pad 15 are electrically connected to each other through the wiring conductor 12. The wiring conductor 12, the semiconductor element connection pad 14, and the external connection pad 15 are formed of a plated conductor layer. The electrode terminal T of the semiconductor element S is connected to the semiconductor element connection pad 14 via solder. The external connection pad 15 is connected to the wiring conductor of the external electric circuit board.

  The wiring board 20 is manufactured as follows. First, as shown in FIG. 5A, a metal foil 32 is supported on a flat support substrate 31. The support substrate 31 and the metal foil 32 are laminated with an intervening layer 33 interposed therebetween. The support substrate 31 and the intervening layer 33 are fixed to each other. The metal foil 32 and the intervening layer 33 are in close contact with each other through an adhesive layer (not shown) so as to be peeled off. The support substrate 31 and the metal foil 32 are fixed. The support substrate 31 is made of a thermosetting resin containing glass cloth. The metal foil 32 is made of copper foil. The intervening layer 33 is made of a copper foil or a resin film.

  Next, as shown in FIG. 5B, the plated conductor layer 14 a is formed on the metal foil 32. The plated conductor layer 14 a is to be the semiconductor element connection pad 14. The plated conductor layer 14a is made of electrolytic copper plating.

  Next, as shown in FIG. 5C, the first insulating resin layer 11a and the wiring conductor 12 are formed on the metal foil 32 and the plated conductor layer 14a. A via hole 13 for connecting to the plated conductor layer 14a is formed in the insulating resin layer 11a. The plated conductor layer 14 a and the wiring conductor 12 are electrically connected to each other through the via hole 13.

  Next, as shown in FIG. 5D, the next insulating resin layer 11b and the wiring conductor 12 are formed on the insulating resin layer 11a and the wiring conductor 12 thereon, and the next insulating resin layer 11c is further formed. Then, the wiring conductor 12 is formed. Via holes 13 are also formed in the insulating resin layers 11b and 11c. The upper and lower wiring conductors 12 are electrically connected to each other through the via hole 13.

  Next, as shown in FIG. 5E, the final insulating resin layer 11d is laminated, and the external connection pads 15 are formed on the insulating resin layer 11d. The external connection pad 15 is composed of a part of the wiring conductor 12. A via hole 13 is also formed in the insulating resin layer 11d. The external connection pad 15 is electrically connected to the underlying wiring conductor 12 through the via hole 13. As a result, the external connection pad 15 is electrically connected to the plating conductor layer 14 a via the wiring conductor 12.

  Next, as shown in FIG. 6F, a portion corresponding to the region where the metal foil 32 and the support substrate 31 are fixed is cut off. Thereby, only the part corresponding to the area | region where metal foil 32 and interposition layer 33 were stuck so that peeling was possible remains.

  Next, as shown in FIG. 6G, the metal foil 32 and the support substrate 31 are separated by peeling the metal foil 32 and the intervening layer 33. Thereby, the metal foil 32 is exposed to the outside.

  Finally, as shown in FIG. 6H, the exposed metal foil 32 is removed by etching. Thereby, the plating conductor layer 14a embedded in the insulating resin layer 11a is exposed to the outside. The exposed plated conductor layer 14 a becomes the semiconductor element connection pad 14. At this time, the plating conductor layer 14a is also etched by about 2 to 3 μm. Therefore, the exposed surface of the semiconductor element connection pad 14 is recessed by about 2 to 3 μm from the surface of the insulating resin layer 11a.

  However, in the conventional wiring board 20, as described above, the semiconductor element connection pad 14 is recessed by about 2 to 3 μm from the surface of the insulating resin layer 11a. Therefore, an electrical connection failure is likely to occur between the semiconductor element connection pad 14 and the electrode terminal T of the semiconductor element S. This is because good contact between the semiconductor element connection pad 14 recessed from the surface of the insulating resin layer 11a and the electrode terminal T of the semiconductor element S is hindered by the recess.

  In addition, there is a wiring board in which the semiconductor element connection pads are not embedded in the insulating resin layer, but are simply projected on the surface of the insulating resin layer. In this case, the semiconductor element connection pads are insulated particularly when the semiconductor element connection pads are small. It becomes easy to peel from the resin layer.

JP 2007-300167 A

  The problem to be solved by the present invention is to provide a wiring board having good electrical connection between a semiconductor element connection pad embedded in an insulating resin layer and an electrode terminal of the semiconductor element, and a method for manufacturing the same. .

  The wiring board of the present invention has an insulating base formed by laminating a plurality of insulating resin layers and a connection surface embedded in the upper surface side of the uppermost insulating resin layer and connected to electrode terminals of a semiconductor element. Projecting from the upper surface, the semiconductor element connection pad made of a plated conductor layer, and attached to the lower surface of the insulating base, and to the semiconductor element connection pad via a wiring conductor provided inside the insulating base And an external connection pad which is electrically connected.

  In the method for manufacturing a wiring board according to the present invention, a metal foil is detachably supported on a flat support substrate, and a first plating conductor layer serving as a semiconductor element connection pad is formed on the metal foil in a predetermined pattern. A step of laminating a first insulating resin layer to be an uppermost insulating resin layer on the metal foil and on the first plated conductor layer, and on the first insulating resin layer, the first insulating resin layer; Forming a wiring conductor electrically connected to the plating conductor layer; laminating a next insulating resin layer on the first insulating resin layer and the wiring conductor; and the next insulating resin layer A step of forming a wiring conductor of a next layer electrically connected to the wiring conductor, and a lamination of an insulating resin layer of the next layer on the insulating resin layer of the next layer and on the wiring conductor of the next layer Repeat the formation of the wiring conductor of the next layer several times as necessary Forming an external connection pad electrically connected to the first plating conductor via the wiring conductor on the insulating resin layer laminated last, the metal foil, and the support substrate Separating the metal foil and exposing the metal foil, removing the metal foil by etching, and denting the surface of the first plated conductor layer from the surface of the first insulating resin layer, A second plating conductor layer having a thickness protruding from the surface of the first insulating resin layer is formed on the surface of the first plating conductor layer, and the second plating conductor layer and the first plating conductor layer are formed. And a step of forming a semiconductor element connection pad comprising:

  According to the wiring board of the present invention, the semiconductor element connection pad embedded in the uppermost insulating resin layer has a connection surface protruding from the surface of the uppermost insulating resin layer because the connection surface connected to the semiconductor element protrudes from the surface of the semiconductor resin. The element connection pad is difficult to peel off from the uppermost insulating resin layer, and electrical connection between the semiconductor element connection pad and the electrode terminal of the semiconductor element can be improved.

  According to the method for manufacturing a wiring board of the present invention, when removing the metal foil by etching, the first plating conductor layer is recessed from the surface of the first insulating resin layer, and then the first plating is performed. A semiconductor element connection pad comprising a first plated conductor layer and a second plated conductor layer formed on the surface of the conductor layer by forming a second plated conductor layer having a thickness protruding from the surface of the first insulating resin layer. Therefore, the semiconductor element connection pad is embedded in the first insulating resin layer, which is the uppermost insulating resin layer, and the connection surface with the electrode terminal of the semiconductor element protrudes from the first insulating resin layer. Thus, it is possible to provide the wiring board thus obtained very easily. As a result, a wiring board is provided in which the semiconductor element connection pad is not easily peeled off from the first insulating resin layer, and the electrical connection between the semiconductor element connection pad and the electrode terminal of the semiconductor element can be improved. can do.

FIG. 1 is a schematic sectional view showing an embodiment of a wiring board according to the present invention. FIG. 2 is a schematic cross-sectional view for each process for explaining an embodiment of the method for manufacturing a wiring board of the present invention. FIG. 3 is a schematic cross-sectional view for each step for explaining an embodiment of the method for manufacturing a wiring board of the present invention. FIG. 4 is a schematic cross-sectional view showing a conventional wiring board. FIG. 5 is a schematic cross-sectional view for each process for explaining a conventional method of manufacturing a wiring board. FIG. 6 is a schematic cross-sectional view for each process for explaining a conventional method of manufacturing a wiring board.

  Next, an embodiment of the wiring board according to the present invention will be described with reference to FIG. As shown in FIG. 1, the wiring board 10 includes an insulating base 1 and a wiring conductor 2. A large number of semiconductor element connection pads 4 are formed on the upper surface of the insulating substrate 1. Further, a large number of external connection pads 5 are formed on the lower surface of the insulating substrate 1.

  The insulating base 1 is formed by laminating a plurality of insulating resin layers 1a to 1d. Each of the insulating resin layers 1a to 1d is made of, for example, an electrically insulating material obtained by impregnating and applying a thermosetting resin to a glass cloth base material. As the thermosetting resin, epoxy resin, bismaleimide triazine resin, polyimide resin or the like is used. The thickness of each insulating resin layer 1a-1d is about 50-200 micrometers, respectively. Via holes 3 are formed in the respective insulating resin layers 1a to 1d. The diameter of the via hole 3 is about 30 to 100 μm.

  The wiring conductor 2 is deposited on the surfaces of the insulating resin layers 1 a to 1 d and the via holes 3. The wiring conductors 2 positioned above and below the insulating resin layers 1 a to 1 d are electrically connected to each other through the via hole 3. The wiring conductor 2 is mainly composed of a copper plating layer. The thickness of the wiring conductor 2 is about 5 to 20 μm.

  A large number of semiconductor element connection pads 4 are arranged in a lattice pattern. The electrode terminal T of the semiconductor element S is connected to the upper surface of the semiconductor element connection pad 4. The semiconductor element connection pad 4 is circular in plan view. The diameter of the semiconductor element connection pad 4 is about 30 to 100 μm. The semiconductor element connection pad 4 is embedded on the upper surface side of the uppermost insulating resin layer 1a. The buried depth is about 5 to 20 μm. The upper surface of the semiconductor element connection pad 4 protrudes from the upper surface of the insulating resin layer 1a. The protruding height is about 1 to 20 μm. The semiconductor element connection pad 4 includes a first plating conductor layer 4a and a second plating conductor layer 4b. The first plated conductor layer 4a is completely buried in the insulating resin layer 1a. As for the 2nd plating conductor layer 4b, the lower surface side is embed | buried in the insulating resin layer 1a, and the upper surface side protrudes from the insulating resin layer 1a. The thickness of the 1st plating conductor layer 4a and the 2nd plating conductor layer 4b is about 2-20 micrometers, respectively. These plating conductor layers 4a and 4b are made of a copper plating layer.

  Many external connection pads 5 are arranged in a grid pattern. The external connection pad 5 is connected to a wiring conductor of an external electric circuit board. The external connection pad 5 is circular in plan view. The diameter of the external connection pad 5 is about 200 to 800 μm. The external connection pad 5 is formed by a wiring conductor 2 deposited on the lower surface of the lowermost insulating resin layer 1d. The external connection pad 5 is electrically connected to the semiconductor element connection pad 4 through the wiring conductor 2.

  Then, the semiconductor element S is mounted on the wiring board 10 by connecting the electrode terminal T of the semiconductor element S to the upper surface of the semiconductor element connection pad 4 via solder. At this time, since the semiconductor element connection pad 4 is embedded in the upper surface side of the insulating resin layer 1a, the semiconductor element connection pad 4 is firmly locked to the insulating resin layer 1a and hardly peels off. Further, since the connection surface connected to the electrode terminal T of the semiconductor element S protrudes from the surface of the insulating resin layer 1a, the electrical connection between the semiconductor element connection pad 4 and the electrode terminal T of the semiconductor element S is good. Can be.

  In addition, it is preferable that the connection surface connected to the electrode terminal T of the semiconductor element S is a convex curved surface. In this case, when the electrode terminal T of the semiconductor element S is connected to the connection surface of the semiconductor element connection pad 4 via the solder, the solder sequentially wets and spreads from the apex of the connection surface to the periphery thereof. It becomes possible to make a very good connection without entraining. The radius of curvature of the connection surface is preferably in the range of 0.5 to 3 times the width of the semiconductor element connection pad 4.

  Next, an embodiment of the method for manufacturing a wiring board according to the present invention will be described with reference to FIGS. 2 and 3 by taking as an example the case of manufacturing the wiring board 10 described above.

  First, as shown in FIG. 2A, a metal foil 22 is supported on a flat support substrate 21. The support substrate 21 and the metal foil 22 are laminated with an intervening layer 23 interposed therebetween. The support substrate 21 and the intervening layer 23 are fixed to each other. The metal foil 22 and the intervening layer 23 are in close contact with each other via an adhesive layer (not shown) so as to be peeled off. The support substrate 21 and the metal foil 22 are fixed to each other. The support substrate 21 is made of a thermosetting resin containing glass cloth. The thickness of the support substrate 21 is about 400 to 800 μm. The metal foil 22 is made of copper foil. The thickness of the metal foil 22 is about 3 to 18 μm. The intervening layer 23 is made of a copper foil or a resin film. The thickness of the intervening layer 23 is about 3 to 18 μm. The thickness shown here is merely an example, and may be a thickness different from the thickness described above.

  Next, as shown in FIG. 2B, the first plated conductor layer 4 a is formed on the metal foil 22 in a predetermined pattern. The first plated conductor layer 4 a becomes the semiconductor element connection pad 4. The first plating conductor layer 4a is made of electrolytic copper plating. The thickness of the 1st plating conductor layer 4a is about 5-20 micrometers. Such a first plating conductor layer 4a is formed by forming a plating mask having an opening pattern corresponding to the first plating conductor layer 4a on the metal foil 22, and then exposing the metal foil exposed in the opening pattern of the plating mask. After the electrolytic copper plating layer is deposited on 22 to a desired thickness, it is formed by removing the plating mask.

  Next, as shown in FIG. 2C, the first insulating resin layer 1a and the wiring conductor 2 are formed on the metal foil 22 and the first plated conductor layer 4a. A via hole 3 for connecting to the first plated conductor layer 4a is formed in the first insulating resin layer 1a. The first plating conductor layer 4a and the wiring conductor 2 are electrically connected to each other through the via hole 3. In the first insulating resin layer 1a, a prepreg obtained by impregnating and drying an uncured thermosetting resin on a glass cloth substrate is placed on the metal foil 22 on which the first plated conductor layer 4a is formed. In addition, it is formed by heat curing after pressing while heating. The via hole 3 is formed by laser processing, blast processing, or the like. The wiring conductor 2 is formed by a known semi-additive method.

  Next, as shown in FIG. 2D, on the first insulating resin layer 1a and the wiring conductor 2 thereon, the next insulating resin layer 1b is laminated and the wiring conductor 2 is further formed. The next insulating resin layer 1c and the wiring conductor 2 are formed. Via holes 3 are also formed in these insulating resin layers 1b and 1c. The upper and lower wiring conductors 2 are electrically connected to each other through the via hole 3. The insulating resin layers 1b and 1c and the wiring conductor 2 thereon are formed in the same manner as the first insulating resin layer 1a and the wiring conductor 2 thereon.

  Next, as shown in FIG. 2E, the final insulating resin layer 1d is laminated, and the wiring conductor 2 including the external connection pads 5 is formed on the insulating resin layer 1d. A via hole 3 is also formed in the insulating resin layer 1d. The external connection pad 5 is electrically connected to the underlying wiring conductor 2 through the via hole 3. As a result, the external connection pad 5 is electrically connected to the first plating conductor layer 4 a via the wiring conductor 2. The insulating resin layer 1d and the wiring conductor 2 thereon are formed in the same manner as the insulating resin layers 1a to 1c and the wiring conductor 2 thereon.

  Next, as shown in FIG. 3F, a portion corresponding to a region where the metal foil 22 and the support substrate 21 are fixed is cut off by cutting. Thereby, only the part corresponding to the area | region where metal foil 22 and the intervening layer 23 contact | adhered so that peeling was possible remains. A dicer or a router is used for cutting.

  Next, as illustrated in FIG. 3G, the metal foil 22 and the support substrate 21 are separated by separating the metal foil 22 and the intervening layer 23. Thereby, the metal foil 22 is exposed to the outside.

  Next, as shown in FIG. 3H, the exposed metal foil 22 is removed by etching. As a result, the first plated conductor layer 4a embedded in the first insulating resin layer 1a is exposed to the outside. At this time, the first plating conductor layer 4a is also etched by a thickness of about 2 to 3 μm. Therefore, the exposed surface of the first plated conductor layer 4a is recessed by about 2 to 3 μm from the surface of the first insulating resin layer 1a.

  Finally, as shown in FIG. 3I, the second plated conductor layer 4b is formed on the exposed surface of the first plated conductor layer 4a so as to protrude from the surface of the first insulating resin layer 1a. The height at which the second plated conductor layer 4b protrudes from the surface of the first insulating resin layer 1a is about 1 to 20 μm. The second plating conductor layer 4b is formed by depositing an electrolytic copper plating layer on the exposed surface of the first plating conductor layer 4a. In this case, for example, plating lead wirings (not shown) for electrically connecting the external connection pads 5 are provided in advance on the exposed surface of the insulating resin layer 11d, and the electrolytic plating is performed via the plating lead wires. Electrolytic plating is performed by supplying the electric charge. An unnecessary part of the plating lead wire is removed by etching or the like after electrolytic plating. Thereby, the wiring board 10 shown in FIG. 1 is completed.

  As described above, according to the method for manufacturing the wiring substrate 10 of this example, when the metal foil 22 is removed by etching, the first plating conductor layer 4a is recessed from the surface of the first insulating resin layer 1a. A second plating conductor layer 4b having a thickness protruding from the surface of the first insulating resin layer 1a is formed on the surface of the first plating conductor layer 4a, whereby the first plating conductor layer 4a and the second plating conductor layer 4a are formed. Since the semiconductor element connection pad 4 including the plated conductor layer 4b is formed, the semiconductor element connection pad 4 is embedded in the first insulating resin layer 1a which is the uppermost insulating resin layer, and the semiconductor element S The wiring board 10 whose connection surface with the electrode terminal T protrudes from the first insulating resin layer 1a can be provided very easily. Thereby, the semiconductor element connection pad 4 is not easily peeled off from the first insulating resin layer 1a, and the electrical connection between the semiconductor element connection pad 4 and the electrode terminal T of the semiconductor element S can be improved. A simple wiring board 10 can be provided.

  In addition, when forming the 2nd plating conductor layer 4b which comprises the semiconductor element connection pad 4, it is preferable that the surface of the 2nd plating conductor layer 4b becomes a convex curved surface. Thus, by connecting the electrode terminal T of the semiconductor element S to the connection surface of the semiconductor element connection pad 4 via solder by making the surface of the second plated conductor layer 4b a convex curved surface. Since the solder spreads sequentially from the apex of the connection surface to the periphery thereof, it is possible to provide the wiring board 10 that can be connected extremely well without involving voids in the solder. In this case, the radius of curvature of the surface of the second plating conductor layer 4 b is preferably in the range of 0.5 to 3 times the width of the semiconductor element connection pad 4. In order to make the surface of the second plating conductor layer 4b a convex curved surface, the thickness of the second plating conductor layer 4b protruding from the surface of the first insulating resin layer 1a may be made sufficiently thick. The thicker the thickness, the higher the height of the curved surface vertex and the smaller the radius of curvature.

DESCRIPTION OF SYMBOLS 1 .... Insulation base | substrate 1a-1d .. Insulation resin layer 2 .... Wiring conductor 4 .... Semiconductor element connection pad 4a ... 1st plating conductor layer 4b 2nd plating conductor layer 5 External connection pad 21 Support substrate 22 Metal foil

Claims (6)

  An insulating base formed by laminating a plurality of insulating resin layers vertically and an upper surface of the uppermost insulating resin layer are embedded, and a connection surface connected to an electrode terminal of a semiconductor element protrudes from the upper surface. A semiconductor element connection pad made of a plated conductor layer, and is attached to the lower surface of the insulating base, and is electrically connected to the semiconductor element connection pad via a wiring conductor provided inside the insulating base. And an external connection pad.   The wiring board according to claim 1, wherein the connection surface is a convex curved surface.   3. The wiring board according to claim 2, wherein a radius of curvature of the curved surface is 0.5 to 3 times a width of the semiconductor element connection pad.   A step of detachably supporting a metal foil on a flat support substrate, a step of forming a first plating conductor layer serving as a semiconductor element connection pad on the metal foil in a predetermined pattern, the metal foil and the first A first insulating resin layer that is an uppermost insulating resin layer is laminated on one plated conductor layer, and is electrically connected to the first plated conductor layer on the first insulating resin layer. Forming a wiring conductor; laminating a next insulating resin layer on the first insulating resin layer and the wiring conductor; and electrically connecting the wiring conductor on the insulating resin layer of the next layer. It is necessary to form a connected next-layer wiring conductor, and to laminate the next-layer insulating resin layer and the next-layer wiring conductor on the next-layer insulating resin layer and the next-layer wiring conductor. Depending on the process repeated several times and the last laminated Forming an external connection pad electrically connected to the first plating conductor via the wiring conductor on the resin layer; and separating the metal foil and the support substrate to expose the metal foil And removing the metal foil by etching and indenting the surface of the first plating conductor layer from the surface of the first insulating resin layer; and on the surface of the first plating conductor layer. Forming a second plating conductor layer having a thickness protruding from the surface of the first insulating resin layer, and forming a semiconductor element connection pad comprising the second plating conductor layer and the first plating conductor layer; And a process for manufacturing the wiring board.   5. The method of manufacturing a wiring board according to claim 4, wherein the second plating conductor layer is formed so that a surface of the second plating conductor layer is a convex curved surface.   6. The method of manufacturing a wiring board according to claim 5, wherein the curvature radius of the curved surface is 0.5 to 3 times the width of the semiconductor element connection pad.

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