Printed wiring board with built-in electronic component and manufacturing method thereof

Abstract

To provide a printed wiring board in which an insulating layer covering an opening of a core substrate incorporating electronic components has a flat surface.SOLUTION: In a printed wiring board having an electronic component built into a core substrate, the core substrate has conductor layers on one side and the other side and an opening penetrating the core substrate between the one side and the other side. The electronic component is built into the opening, a first insulating layer is formed on the conductor layer on the one side of the core substrate and on the opening, a second insulating layer is formed on the conductor layer on the other side of the core substrate and on the opening, and each of the first insulating layer and the second insulating layer is formed from a resin film.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a printed wiring board having an electronic component built into a core substrate, and a method for manufacturing the printed wiring board. [Background technology]

[0002] Conventionally, a printed wiring board having electronic components built into a core substrate is known from Patent Document 1. Figures 3(a) to 3(d) are cross-sectional views sequentially illustrating an outline of a method for manufacturing this conventional printed wiring board.

[0003] 3(a), in the conventional printed wiring board, conductor layers C100 and C200 are formed on the first surface S100 and the second surface S200, which are both surfaces of the core substrate CB100, and a recess H100 with a bottom is formed on the first surface S100 of the core substrate CB100. Meanwhile, stud bumps SB100 are formed by bonding to connection terminals (not shown) on the back surface of the built-in electronic component P100.

[0004] Next, as shown in Fig. 3(b), the electronic component P100 is fixed in the recess H100 with the stud bumps SB100 facing the first surface S100. Furthermore, as shown in Fig. 3(c), the first surface S100 and the second surface S200 of the core substrate CB100 are coated with resin to form the first insulating layer 110 and the second insulating layer 210, respectively. The resin of the first insulating layer 110 also serves to seal the electronic component P100 in the recess H100.

[0005] Then, as shown in FIG. 3(d), via holes 130, 230 are formed by laser in the first insulating layer 110 on the first surface S100 of the core substrate CB100 and the second insulating layer 210 on the second surface S200, exposing the connection portions of the underlying conductor layers C100 and C200 and the stud bump SB100.

[0006] Next, conductor layers are formed on the first insulating layer 110 and the second insulating layer 210, respectively, and via conductors (not shown) connecting these conductor layers to the connection portions of the conductor layers C100, C200 and the stud bump SB100 are formed in the via holes 130, 230 of the first and second insulating layers 110, 210, and build-up layers (not shown) are laminated and formed on the first surface S100 and the second surface S200 of the core substrate CB100, respectively. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 09-321408 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in this conventional printed wiring board, the first insulating layer 110 is formed by a resin coating, so when an electronic component P100 having a thickness thinner than that of the core substrate CB100 is embedded in an opening that penetrates the core substrate CB100 to form a bottomless recess H100, the surface of the first insulating layer 110 on and near the electronic component P100 becomes recessed, which hinders the formation of the conductor layers, etc., of the upper build-up layer.

[0009] Furthermore, if one attempts to eliminate the depressions in the surface of the first insulating layer 110 and make it flat, the first insulating layer 110 will become particularly thick on and near the electronic component P100, which may result in a problem of greater variation in the thickness of the first insulating layer 110.

[0010] An object of the present invention is to provide a printed wiring board having an electronic component having a thickness thinner than that of a core substrate incorporated in an opening penetrating the core substrate, wherein the surface of an insulating layer formed on the conductor layer of the core substrate and on the electronic component in the core substrate is flat and substantially free of depressions, and the insulating layer also has little variation in thickness, and a method for manufacturing the printed wiring board. [Means for solving the problem]

[0011] The printed wiring board of the present invention comprises: A printed wiring board having electronic components built into a core substrate, the core substrate has a conductor layer on one surface and the other surface, and has an opening penetrating the core substrate between the one surface and the other surface; The electronic component is housed in the opening, a first insulating layer is formed on the conductor layer on the one surface of the core substrate and on the opening; a second insulating layer is formed on the conductor layer on the other surface of the core substrate and on the opening; the first insulating layer and the second insulating layer are each formed of a resin film; It is characterized by:

[0012] The method for producing a printed wiring board of the present invention further comprises the steps of: A method for manufacturing a printed wiring board having an electronic component embedded in a core substrate, comprising the steps of: forming the core substrate so as to have a conductor layer on one surface and the other surface and to have an opening penetrating the core substrate between the one surface and the other surface; providing a tape covering the opening on the other surface of the core substrate; placing the electronic component on the tape within the opening; forming a first insulating layer by laminating a resin film on the conductor layer on the one surface of the core substrate and on the opening; removing a tape covering the opening on the other surface of the core substrate; laminating a resin film on the other surface of the core substrate to form a second insulating layer; The present invention is characterized in that it includes:

[0013] In the printed wiring board and its manufacturing method of the present invention, the step obtained by subtracting the thickness (Y) of the electronic component from the thickness (X) of the core substrate is preferably equal to or smaller than the thickness (Z) of the resin film of the first insulating layer (i.e., Z≧XY). As a result, even if the step between the core substrate and the electronic component is large, the step can be filled with the resin of the resin film of the first insulating layer, which has a thickness greater than or equal to the step, so that the surface of the first insulating layer can be formed substantially flat. More preferably, when the relationship between the thickness (Y) of the electronic component and the thickness (X) of the core substrate is 1 / 2≧Y / X≧1 / 5 (i.e., X / 2≧Y≧X / 5), this is particularly effective since the step is large. [Brief description of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view illustrating a schematic diagram of an embodiment of a printed wiring board according to the present invention. [Diagram 2] 2(a) to 2(g) are explanatory views showing a manufacturing process in one embodiment of a method for manufacturing a printed wiring board of the present invention, for manufacturing the printed wiring board of the above embodiment. [Diagram 3] 1(a) to 1(d) are explanatory views showing a manufacturing process in a conventional method for manufacturing a printed wiring board. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An embodiment of the printed wiring board of the present invention will be described below with reference to the drawings. Fig. 1 is a cross-sectional view showing a schematic diagram of an embodiment of the printed wiring board of the present invention, and Figs. 2(a) to 2(g) are explanatory diagrams showing a manufacturing process in an embodiment of the method for manufacturing a printed wiring board of the present invention for manufacturing the printed wiring board of the above embodiment. In the embodiment shown in Figs. 1 and 2, the dimensions of each member, particularly the height direction dimensions, are shown in dimensions different from the actual dimensions in order to allow a better understanding of the features of the present invention.

[0016] 1, the printed wiring board of this embodiment includes a core substrate CB1, conductor layers C1 and C2 formed on a first surface S1, which is one surface of the core substrate CB1, and a second surface S2, which is the other surface of the core substrate CB1, respectively, and build-up layers (only a first insulating layer 11 and a second insulating layer 21 are shown) formed and laminated on the first surface S1, the second surface S2, and the conductor layers C1 and C2. The printed wiring board of this embodiment also includes an electronic component P1, such as an IC, built into the core substrate CB1.

[0017] The conductor layers C1, C2 formed on the first surface S1 and the second surface S2 of the core substrate CB1 each have a predetermined circuit pattern, and the conductor layers C1, C2 may be connected via a through-hole conductor (not shown) that penetrates the core substrate CB1. The core substrate CB1 also has an opening H1 between the first surface S1 and the second surface S2 that penetrates the core substrate CB1 and forms a bottomless recess, and the electronic component P1 is built into the opening H1. The core substrate CB1 is formed of an electrically insulating resin material. This resin material may be composed of, for example, a resin composition containing reinforcing fibers and an epoxy resin.

[0018] A first insulating layer 11, which is the bottom insulating layer of the build-up layers, is formed on the conductor layer C1 and opening H1 of the first surface S1 of the core substrate CB1, and a second insulating layer 21, which is the bottom insulating layer of the build-up layers, is formed on the conductor layer C2 and opening H1 of the second surface S2 of the core substrate CB1, and the first insulating layer 11 and the second insulating layer 21 are each formed of an electrically insulating resin film. These resin films may be composed of a resin composition containing an inorganic filler such as silica or alumina and an epoxy resin.

[0019] On the first insulating layer 11 and the second insulating layer 21, the above-mentioned one or more build-up layers are formed by alternately stacking insulating layers and conductor layers and forming via conductors connecting the upper and lower conductor layers sandwiching the insulating layers. The lowermost conductor layers of the build-up layers are connected to the conductor layers C1 on the first surface S1 and the conductor layers C2 on the second surface S2 of the core substrate CB1 through via conductors (not shown) that penetrate the first insulating layer 11 and the second insulating layer 21 that form the lowermost insulating layers of the build-up layers. The lowermost conductor layer of the build-up layer on the first insulating layer 11 is connected to the bump B1 of the electronic component P1 in the opening H1 through a via conductor (not shown) that penetrates the first insulating layer 11 that forms the lowermost insulating layer.

[0020] In a manufacturing process of one embodiment of the method for manufacturing a printed wiring board of the present invention for manufacturing the printed wiring board of the above embodiment, first, a core substrate CB1 and an electronic component P1 are prepared as shown in Fig. 2(a). A conductor layer C1 and a conductor layer C2 are formed on a first surface S1, which is one surface of the core substrate CB1, and a second surface S2, which is the other surface of the core substrate CB1, respectively, by, for example, electrolytic copper plating.

[0021] The core substrate CB1 also has an opening H1 formed by, for example, a laser, penetrating the core substrate CB1 between the first surface S1 and the second surface S2 to form a bottomless recess. The electronic component P1 is, for example, an IC, and has a plurality of bumps B1 formed on its upper surface as connection terminals. The size of the opening H1 is set to a size that allows the electronic component P1 to be housed therein without significant play. In this embodiment, the thickness of the core substrate CB1 including the conductor layers C1 and C2 is designated as X, and the thickness of the electronic component P1 including the bumps B1 is designated as Y.

[0022] 2(b), the adhesive surface of adhesive tape T is attached onto the second surface S2 of core substrate CB1 and the conductor layer C2 on the second surface S2 side, and the end of opening H1 on the second surface S2 side is closed with the adhesive tape T. Next, as shown in Fig. 2(c), electronic component P1 is inserted into opening H1 from the end of opening H1 on the first surface S1 side with bumps B1 facing the first surface S1 side, and fixed by adhering it to the adhesive surface of the adhesive tape T.

[0023] 2(d), a resin film F1 for a first insulating layer is disposed on the first surface S1 of the core substrate CB1 and on the conductor layer C1 on the first surface S1 side so as to close the end of the opening H1 on the first surface S1 side. In this embodiment, the thickness Z of the resin film F1 is set to Z≧XY, where X is the thickness of the core substrate CB1 including the conductor layers C1 and C2, and Y is the thickness of the electronic component P1 including the bump B1.

[0024] 2(e), the resin film F1 is heated and pressed against the core substrate CB1 on a flat plate, causing the softened resin of the resin film F1 to flow around the conductor layer C1 and into the gap between the inner peripheral surface of the opening H1 and the outer peripheral surface of the electronic component P1, forming a flat first insulating layer 11 that is substantially free of surface dents from the resin film F1. This heating and pressing may be performed, for example, by placing the resin film F1 and the core substrate CB1 between a horizontal fixed table of a press device placed in a heated atmosphere and a movable table above it that moves up and down while maintaining the horizontality, and pressing them with the movable table.

[0025] 2(f), when the resin of the resin film F1 hardens and the electronic component P1 is fixed in the opening H1, the adhesive tape T on the second surface S2 of the core substrate CB1 and the conductor layer C2 on the second surface S2 side are peeled off to expose the end surface of the resin within the end on the second surface S2 side of the opening H1 and the surface of the electronic component P1 in the opening H1 opposite to the bump B1 side. These surfaces become flat by the pressure of the resin film F1 on the flat plate.

[0026] 2(g), the core substrate CB1 and the first insulating layer 11 are inverted together, and a resin film F2 for the second insulating layer 21 is disposed on the end face of the resin in the end on the second surface S2 side of the opening H1 and on the surface of the electronic component P1 in the opening H1 opposite to the bump B1 side. Then, similar to the process shown in FIG. 2(e), the resin film F2 is heated and pressed toward the core substrate CB1 on a flat plate, causing the softened resin of the resin film F2 to flow around the conductor layer C2, and a flat second insulating layer 21 with substantially no surface depressions is formed from the resin film F2.

[0027] This allows the manufacture of the printed wiring board of the embodiment shown in Fig. 1. In the printed wiring board of this embodiment and its manufacturing method, the first insulating layer 11 is formed of the resin film F1, so that the variation in thickness of the first insulating layer is small. Moreover, the thickness Z of the resin film F1 satisfies Z≧XY, where X is the thickness of the core substrate CB1 including the conductor layers C1 and C2, and Y is the thickness of the electronic component P1 including the bumps B1, so that the upper surface of the first insulating layer 11 is formed to be substantially flat.

[0028] The printed wiring board and manufacturing method thereof according to this embodiment are particularly effective when 1 / 2≧Y / X≧1 / 5 (that is, X / 2≧Y≧X / 5), since a large step occurs when this occurs.

[0029] In addition, in the printed wiring board and its manufacturing method of this embodiment, one or more build-up layers are laminated on the first insulating layer 11 and the second insulating layer 21, respectively, but the printed wiring board and its manufacturing method of this invention are not limited to this, and a bump for mounting to, for example, a motherboard may be formed on the second insulating layer 21, and the bump may be connected to the conductor layer C2 through a via hole conductor that penetrates the second insulating layer 21. [Explanation of symbols]

[0030] H1, H100 Opening (recess) P Pressure T adhesive tape B1 Bump SB100 Stud Bump C1, C2, C100, C200 Conductor layers F1, F2 resin film P1, P100 Electronic Components CB1,CB100 core board S1,S100 1st page S2,S200 2nd side 11,110 First insulating layer 21,210 Second insulating layer 130,230 Via holes

Claims

1. A printed wiring board having electronic components built into a core substrate, the core substrate has a conductor layer on one surface and the other surface, and has an opening penetrating the core substrate between the one surface and the other surface; The electronic component is housed in the opening, a first insulating layer is formed on the conductor layer on the one surface of the core substrate and on the opening; a second insulating layer is formed on the conductor layer on the other surface of the core substrate and on the opening; the first insulating layer and the second insulating layer are each formed of a resin film; A printed wiring board comprising:

2. 2. The printed wiring board according to claim 1, wherein a step obtained by subtracting a thickness (Y) of the electronic component from a thickness (X) of the core substrate is equal to or smaller than a thickness (Z) of the resin film of the first insulating layer.

3. 3. The printed wiring board according to claim 1, wherein the relationship between the thickness (Y) of the electronic component and the thickness (X) of the core substrate is 1 / 2≧Y / X≧1 / 5 (i.e., X / 2≧Y≧X / 5).

4. A method for manufacturing a printed wiring board having an electronic component embedded in a core substrate, comprising the steps of: forming the core substrate so as to have a conductor layer on one surface and the other surface and to have an opening penetrating the core substrate between the one surface and the other surface; providing a tape covering the opening on the other surface of the core substrate; placing the electronic component on the tape within the opening; forming a first insulating layer by laminating a resin film on the conductor layer on the one surface of the core substrate and on the opening; removing a tape covering the opening on the other surface of the core substrate; laminating a resin film on the other surface of the core substrate to form a second insulating layer; A method for producing a printed wiring board, comprising:

Images