Printed wiring board

Abstract

To provide a printed wiring board having multi-layers of 7 or more layers of build-up layers on upper and lower surfaces of a core substrate which eliminates its warpage.SOLUTION: A printed wiring board has a plurality of upper build-up layers BU1 to BU7 and a plurality of lower build-up layers which are composed of resin insulation layers and conductors, on each of upper and lower surfaces of a core substrate 2, wherein the build-up layers 7 are 7 or more layers, among the resin insulation layers, a resin insulation layer 3U-7 constituting the uppermost build-up layer BU7 and the lowermost build-up layer is composed of a glass cloth 11, inorganic particles 12 and a resin 13, among the resin insulation layers, the resin insulation layers constituting the build-up layers other than the uppermost and lowermost build-up layers are composed of inorganic particles and a resin, and a frame-like reinforcement material 5 is arranged on the resin insulation layer constituting the uppermost build-up layer.SELECTED DRAWING: Figure 2E

Description

[Technical Field]

[0001] The present invention relates to a printed wiring board having a frame-shaped reinforcing material. [Background technology]

[0002] Conventionally, a printed wiring board having a frame-shaped reinforcing material in order to eliminate warping of the printed wiring board has been known, for example, from Patent Document 1. Figures 3(a) and 3(b) are diagrams for explaining one embodiment of the conventional printed wiring board disclosed in Patent Document 1.

[0003] 3(a), the surface (upper surface) on the IC chip 52 side has small solder pads 53U arranged thereon, so the proportion of the metal portion occupied by the solder pads 53U is small. On the other hand, the surface (lower surface) on the motherboard 54 side has large solder pads 53D, so the proportion of the metal portion is large.

[0004] Therefore, in the technology disclosed in Patent Document 1, a frame-shaped reinforcing member 55 shown in FIG. 3(b) is formed within the resin insulating layer on the periphery of the conductor circuit on the IC chip 52 side of the printed wiring board 51. This increases the metal portion on the IC chip 52 side of the printed wiring board 51, adjusts the ratio of metal portions on the IC chip 52 side to the motherboard 54 side, and increases the strength of the printed wiring board 51, preventing warping of the printed wiring board 51 during manufacturing and use. In FIGS. 3(a) and 3(b), reference numeral 56U denotes a solder bump formed on the solder pad 53U, and reference numeral 56D denotes a solder bump formed on the solder pad 53D. The solder bump 56U is used for electrical connection with the IC chip 52, and the solder bump 56D is used for electrical connection with the motherboard 54. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-135677 Summary of the Invention [Problem to be solved by the invention]

[0006] As shown in FIG. 3(a), this conventional printed wiring board 51 has two buildup layers, BU1 and BU2, and BD1 and BD2, on the top and bottom surfaces of a core substrate 57. The resin insulating layers that make up the buildup layers are composed of epoxy particles and resin. With this configuration, the frame-shaped reinforcing member 55 can still function in the conventional printed wiring board 51, effectively eliminating warpage of the printed wiring board 51. However, in a printed wiring board having multiple buildup layers, for example, seven or more buildup layers, on the top and bottom surfaces of a core substrate, the effect of eliminating warpage may not be fully achieved. [Means for solving the problem]

[0007] The printed wiring board of the present invention is a printed wiring board having multiple buildup layers, each consisting of a resin insulating layer and a conductor layer, on each of the upper and lower surfaces of a core substrate, wherein the buildup layers include seven or more layers, and the resin insulating layers constituting the topmost and bottommost buildup layers among the resin insulating layers are composed of glass cloth, inorganic particles, and resin, and the resin insulating layers constituting the buildup layers other than the topmost and bottommost buildup layers among the resin insulating layers are composed of inorganic particles and resin, and a frame-shaped reinforcing material is arranged on top of the resin insulating layer constituting the topmost buildup layer. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B are diagrams illustrating an embodiment of a printed wiring board according to the present invention. [Figure 2A] 1A to 1C are diagrams illustrating an embodiment of a manufacturing method for manufacturing a printed wiring board according to the present invention. [Figure 2B] 1A to 1C are diagrams illustrating an embodiment of a manufacturing method for manufacturing a printed wiring board according to the present invention. [Figure 2C] 1A to 1C are diagrams illustrating an embodiment of a manufacturing method for manufacturing a printed wiring board according to the present invention. [Figure 2D] 1A to 1C are diagrams illustrating an embodiment of a manufacturing method for manufacturing a printed wiring board according to the present invention. [Figure 2E] 1A to 1C are diagrams illustrating an embodiment of a manufacturing method for manufacturing a printed wiring board according to the present invention. [Figure 3] 1A and 1B are diagrams illustrating an embodiment of a conventional printed wiring board. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of a printed wiring board according to the present invention will be described with reference to the drawings. In the example shown in Figure 1 and Figures 2A to 2E, the dimensions of each component, particularly the height dimension, are shown as dimensions different from the actual dimensions in order to better understand the features of the present invention.

[0010] <One embodiment of the printed wiring board of the present invention> Fig. 1 is a diagram illustrating one embodiment of a printed wiring board of the present invention. In the embodiment shown in Fig. 1, printed wiring board 1 has seven buildup layers (BU-1 to BU-7) made up of resin insulating layers (3U-1 to 3U-7) and conductor layers (4U-1 to 4U-7) on upper surface 2U and seven buildup layers (BD-1 to BD-7) made up of resin insulating layers (3D-1 to 3D-7) and conductor layers (4D-1 to 4D-7) on lower surface 2D, respectively, on upper and lower surfaces 2U and 2D of core substrate 2.

[0011] In the embodiment shown in FIG. 1 , reference numeral 6U denotes a solder bump formed on conductor layer 4U-7 as a solder pad, and reference numeral 6D denotes a solder bump formed on conductor layer 4D-7 as a solder pad. Furthermore, the printed wiring board 1 of the present invention is intended for a board having seven or more buildup layers, with the upper limit being preferably 15 or less. The reason for limiting the number of buildup layers to seven or more is that the effect of using glass cloth in the uppermost and lowermost buildup layers, which is a feature of the present invention described below, can be maximized with seven or more layers. The reason for preferring the number of buildup layers to 15 or less is that if the number of buildup layers exceeds 15, the effect of using glass cloth in the uppermost and lowermost buildup layers, which is a feature of the present invention described above, may not be fully realized.

[0012] 1, among the resin insulating layers (3U-1 to 3U-7 and 3D-1 to 3D-7), the resin insulating layers (3U-7 and 3D-7) constituting the uppermost buildup layer BU-7 and the lowermost buildup layer BD-7 are composed of glass cloth, inorganic particles, and resin. The reason why only the resin insulating layers (3U-7 and 3D-7) constituting the uppermost buildup layer BU-7 and the lowermost buildup layer BD-7 contain glass cloth is to strengthen the buildup layers, which are most effective in preventing warpage.

[0013] Furthermore, in the embodiment of printed wiring board 1 of the present invention shown in FIG. 1, among the resin insulating layers (3U-1 to 3U-7 and 3D-1 to 3D-7), the resin insulating layers (3U-1 to 3U-6 and 3D-1 to 3D-6) that constitute the buildup layers (BU-1 to BU-6 and BD-1 to BD-6) other than the uppermost and lowermost buildup layers (BU-7 and BD-7) are composed of inorganic particles and resin.

[0014] Furthermore, in the embodiment shown in FIG. 1 , in the printed wiring board 1 of the present invention, a frame-shaped reinforcing material 5 is disposed on the resin insulating layer 3U-7 that constitutes the uppermost buildup layer BU-7. The reinforcing material 5 is preferably made of a metal such as copper. The frame-shaped reinforcing material 5 is disposed on the resin insulating layer 3U-7 that constitutes the uppermost buildup layer BU-7 in order to balance the metal portions of the upper and lower buildup layers of the core substrate 2 and to increase the strength of the upper buildup layer, thereby effectively eliminating warping of the printed wiring board 1. The frame-shaped reinforcing material 5 is disposed on the resin insulating layer 3U-7 that constitutes the uppermost buildup layer BU-7 in order to simplify the formation of the reinforcing material 5.

[0015] In the printed wiring board 1 of the present invention described above, the glass cloth, inorganic particles, and resin used in the resin insulating layers (3U-7 and 3D-7) constituting the uppermost buildup layer BU-7 and the lowermost buildup layer BD-7 can be conventionally known. Similarly, the inorganic particles and resin used in the resin insulating layers (3U-1 to 3U-6 and 3D-1 to 3D-6) constituting the buildup layers (BU-1 to BU-6 and BD-1 to BD-6) other than the uppermost and lowermost buildup layers (BU-7 and BD-7) can be conventionally known. The same applies to the core substrate 2.

[0016] According to the printed wiring board of the present invention, among the resin insulation layers, the resin insulation layers constituting the top buildup layer and the bottom buildup layer are composed of glass cloth, inorganic particles and resin, among the resin insulation layers, the resin insulation layers constituting the buildup layers other than the top and bottom buildup layers are composed of inorganic particles and resin, and a frame-shaped reinforcing material is placed on the resin insulation layer constituting the top buildup layer, thereby making it possible to eliminate warping in printed wiring boards having seven or more buildup layers.

[0017] <One embodiment of a manufacturing method for manufacturing a printed wiring board of the present invention> 2A to 2E are diagrams illustrating one embodiment of a manufacturing method for manufacturing a printed wiring board of the present invention. Hereinafter, one embodiment of a manufacturing method for manufacturing a printed wiring board of the present invention will be described in order using FIGS. 2A to 2E. Note that, since the buildup layers formed above and below core substrate 2 have the same structure, only a portion of the buildup layer on the upper side of core substrate 2 is illustrated in the following FIGS. 2A to 2E. Furthermore, the number of buildup layers is seven, the same as in the example shown in FIG. 1.

[0018] First, as shown in Fig. 2A, an intermediate body is prepared in which six buildup layers (BU-1 to BU6) are formed on the upper surface of core substrate 2. This intermediate body can be manufactured by any conventionally known manufacturing method. Next, a conductor layer 4U-7 of a seventh buildup layer BU-7 is formed on the sixth buildup layer BU-6 of the intermediate body.

[0019] Next, as shown in FIG. 2B, solder pads 14 and a resin insulating layer 3U-7 are formed on the conductor layer 4U-7 of the build-up layer BU-7. The resin insulating layer 3U-7 is composed of glass cloth 11, inorganic particles 12, and resin 13. Next, as shown in FIG. 2C, openings 15 are formed in the resin insulating layer 3U-7 to expose the solder pads 14. The openings 15 can be formed using a conventional method, such as a laser. Next, as shown in FIG. 2D, solder bumps 16 are formed on the openings 15 and the solder pads 14.

[0020] Finally, as shown in Fig. 2E, a frame-shaped reinforcing material 5 is formed around the entire outer periphery of the resin insulating layer BU-7, thereby completing the manufacture of the printed wiring board of the present invention. Note that, in the above-described embodiment, any manufacturing steps not specifically mentioned can be carried out by conventionally known methods. [Explanation of symbols]

[0021] 1. Printed wiring board 2 Core Board 3U-1~3U―7 (Upper) resin insulation layer 3D-1~3D-7 (lower) resin insulation layer 4U-1~4U-7 (upper) conductor layers 4D-1~4D-7 (lower) conductor layers 5 Reinforcement 6U (upper) solder bumps 6D (bottom) solder bumps 11 Glass cloth 12 Inorganic particles 13 Resin 14 solder pads 15 Aperture 16 Solder bumps BU-1~BU-7 (upper) build-up layers BD-1~BD-7 (lower) build-up layers

Claims

1. A printed wiring board having a plurality of build-up layers, each made of a resin insulating layer and a conductor layer, on each of the upper and lower surfaces of a core substrate, The build-up layers are 7 or more layers, Among the resin insulating layers, the resin insulating layers constituting the uppermost buildup layer and the lowermost buildup layer are made of glass cloth, inorganic particles, and resin; Among the resin insulating layers, the resin insulating layers constituting the buildup layers other than the uppermost and lowermost buildup layers are composed of inorganic particles and resin, A printed wiring board, wherein a frame-shaped reinforcing material is disposed on the resin insulating layer that constitutes the uppermost buildup layer.

2. The printed wiring board according to claim 1 , wherein the number of build-up layers is 15 or less.

3. The printed wiring board according to claim 1 , wherein the reinforcing material is made of metal.

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