JP2009290044A - Wiring substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board capable of operating a mounted electronic component normally with less noise generated in a signal to be taken in and out of the electronic component mounted on the wiring board.
An electronic component connection pad for signal, grounding, and power supply composed of a part of a wiring conductor layer is formed on an upper surface of an insulating substrate, and a wiring conductor layer is formed on a lower surface of the insulating substrate. And a wiring board formed with signal, grounding and power supply external connection pads 6 electrically connected to the electronic component connection pads 5 through the through conductors 4 and external to the grounding or power supply One of the connection pads 6 is a wiring board formed by exposing a part of the wiring conductor 2 inside the opening A provided in the outermost insulating layer 1b on the lower surface side.
[Selection] Figure 1

Description

  The present invention relates to a wiring board used for mounting electronic components such as semiconductor elements.

  Conventionally, as shown in FIG. 3, a wiring board used for mounting an electronic component such as a semiconductor element is a build-up layer made of a core insulating layer 11a made of, for example, a glass-epoxy plate, and an epoxy resin. A plurality of wiring conductor layers 12 made of a conductor layer such as a copper foil or a copper plating film are provided on the surface of each insulating layer 11a, 11b of an insulating substrate 11 formed by laminating a plurality of insulating layers 11b, and an insulating layer for a core The upper and lower wiring conductor layers 12 are connected by a through conductor (hereinafter referred to as a through-hole conductor) 13 penetrating 11a and a through conductor (hereinafter referred to as a via conductor) 14 penetrating each build-up insulating layer 11b. In such a wiring substrate, a part of the wiring conductor layer 12 provided on the surface of the outermost insulating layer 11b on the upper surface side of the insulating substrate 11 is connected to an electrode of an electronic component E such as a semiconductor element via a solder bump B. A part of the wiring conductor layer 12 formed on the surface of the outermost insulating layer 11b on the lower surface side of the insulating substrate 11 is formed as an external electric circuit board (not shown). The external connection pads 16 that are electrically connected via the external connection terminals T such as solder balls are formed. The electronic component connection pads 15 and the external connection pads 16 are formed on the upper and lower surfaces of the insulating substrate 11. The wiring conductor layer 12, the through-hole conductor 13, and the via conductor 14 provided therebetween are electrically connected to each other. A solder resist layer 17 that exposes the electronic component connection pads 15 and the external connection pads 16 in a predetermined shape and size is laminated on the surface of the outermost insulating layer 11b.

  In this wiring board, after the electrodes of the electronic component E are electrically connected to the electronic component connection pads 15 via the solder bumps B, the external connection pads 16 are connected to the external electric terminals via the external connection terminals T such as solder balls. By connecting to a wiring conductor of a circuit board (not shown), the mounted electronic component E is electrically connected to an external electric circuit.

  By the way, the wiring conductor layer 12 in such a wiring board functions as a signal wiring conductor layer 12 (S), a grounding wiring conductor layer 12 (G), and a power wiring conductor 12 (P) depending on applications. It has become. Among them, the signal wiring conductor layer 12 (S) functions as a conductive path for propagating an electric signal between the electronic component E such as a semiconductor element and the external electric circuit board, and has a thin strip-like conductor pattern. is doing.

  Further, the grounding conductor layer 12 (G) and the power source conductor layer 12 (P) function as a supply path for supplying a ground potential and a power source potential to the electronic component E mounted on the wiring board, respectively. A large-area conductor that has an electromagnetic shielding function and a characteristic impedance adjustment function for the signal wiring conductor layer 12 (S) and is opposite to or adjacent to the signal wiring conductor layer 12 (S). Has a pattern.

The electronic component connection pads 15 and the external connection pads 16 connected to the wiring conductor layers 12 (S), 12 (G), and 12 (P) for signal, grounding, and power supply also correspond to the signals. , Grounding and power supply electronic component connection pads 15 (S), 15 (G), 15 (P) and signal, grounding and power supply external connection pads 16 (S), 16 (G), 16 Although classified into (P), these are formed by exposing a part of the wiring conductor layer 12 provided on the surface of the outermost insulating layer 11b from the solder resist layer 17 in the same shape and size.
JP 2004-273718 A

  However, according to the conventional wiring board, the electronic component connection pad and the external connection pad are each formed from a part of the wiring conductor layer provided on the surface of the outermost insulating layer, and the wiring conductor layer positioned inside thereof. Is connected to the via conductor. Such a via conductor has a diameter of about 30 to 100 μm and acts as an inductance component of about several tens of pH per piece, and accordingly, in the electrical path between the electronic component connection pad and the external connection pad. The inductance will be increased. When the inductance in the electrical path between the electronic component connection pad for grounding and power supply and the external connection pad is high, a high-speed signal of, for example, 3 GHz or more is input / output through the external connection pad to the electronic component mounted on the wiring board. As a result, noise called ringing noise is generated in the signal, and it becomes difficult to normally operate the mounted electronic component.

  The present invention has been devised in view of such conventional problems. The purpose of the present invention is to reduce noise in a signal even when a high-speed signal of 3 Hz or higher is input / output to / from an electronic component mounted on a wiring board. An object of the present invention is to provide a wiring board that is less likely to occur and can normally operate electronic components to be mounted.

  The wiring board according to the present invention includes an insulating substrate formed by laminating a plurality of insulating layers, a wiring conductor layer disposed between the surface of the insulating substrate and each insulating layer, and each of the insulating layers. The wiring conductor layers have through conductors connecting the wiring conductor layers, and signal connection, grounding and power supply electronic component connection pads made of a part of the wiring conductor layers are formed on the upper surface of the insulating substrate, External connection pads for signal, grounding and power supply comprising a part of the wiring conductor layer electrically connected to the electronic component connection pad via the wiring conductor layer and the through conductor on the lower surface of the insulating substrate The wiring board formed by forming one of the external connection pads for grounding or power supply inside the insulating layer in an opening provided in the insulating layer of the outermost layer on the lower surface side Exposed part of the conductor layer And it is characterized in that it is formed by causing.

  According to the wiring board of the present invention, one of the external connection pads for grounding or power supply is provided in the opening provided in the outermost insulating layer on the lower surface side of the insulating substrate in the wiring conductor layer inside the insulating layer. Compared to the case where both the grounding and power supply external connection pads are made of a part of the wiring conductor layer provided on the outermost layer surface on the lower surface side of the insulating substrate because it is formed by exposing a part. The number of through conductors for connecting the electronic component connection pads for grounding or power supply and the external connection pads can be reduced by one layer of the insulating layer. Accordingly, the inductance in the electrical path between the grounding or power supply electronic component connection pad and the external connection pad can be reduced accordingly. As a result, even when a high-speed signal of 3 GHz or more is input / output to / from an electronic component mounted on the wiring board, a wiring board that generates less noise in the signal and can normally operate the mounted electronic component. Can be provided.

Next, the wiring board of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of a wiring board according to the present invention. In FIG. 1, 1 is an insulating substrate, 2 is a wiring conductor, 3 and 4 are through conductors, 5 is an electronic component connection pad, and 6 is an external connection pad. These are mainly used for mounting an electronic component E such as a semiconductor element. A wiring board is configured.

  The insulating substrate 1 is made of, for example, epoxy resin or bismaleimide triazine on the upper and lower surfaces of a core insulating layer 1a formed by impregnating a glass fabric in which glass fibers are woven vertically and horizontally with a thermosetting resin such as epoxy resin or bismaleimide triazine resin. A plurality of build-up insulating layers 1b made of a thermosetting resin such as a resin are laminated, and a plurality of wirings made of a conductor layer such as a copper foil or a copper plating film on the surface of each insulating layer 1a, 1b. A conductor layer 2 is formed, and penetrates through the core insulating layer 1a and penetrates through conductors (hereinafter referred to as through-hole conductors) 3 and each build-up insulating layer 1b. 4) is formed.

  The core insulating layer 1a constituting the insulating substrate 1 has a thickness of about 0.3 to 1.5 mm, and has a plurality of through holes (hereinafter referred to as through holes) having a diameter of about 0.2 to 1.0 mm from the upper surface to the lower surface. 7). And the wiring conductor layer 2 is attached to the upper and lower surfaces, and the through-hole conductor 3 is attached to the inner surface of each through-hole 7, and the wiring conductor layers 2 on the upper and lower surfaces of the insulating layer 1a are formed. They are electrically connected through the through-hole conductor 3.

  Such an insulating layer 1a is manufactured by thermally curing a sheet in which a glass fabric is impregnated with an uncured thermosetting resin, and then drilling the sheet from the upper surface to the lower surface. In addition, the wiring conductor layer 2 on the upper and lower surfaces of the insulating layer 1a has a copper foil having a thickness of about 5 to 50 μm attached to the entire upper and lower surfaces of the sheet for the insulating layer 1a, and the copper foil is etched after the sheet is cured. A predetermined pattern is formed by processing. The through-hole conductor 3 on the inner surface of the through-hole 7 is provided with a copper plating film having a thickness of about 5 to 50 μm by electroless plating and electrolytic plating on the inner surface of the through-hole 7 after providing the through-hole 7 in the insulating layer 1a. It is formed by precipitating.

  Furthermore, the insulating layer 1 a is filled with a hole filling resin 8 made of a thermosetting resin such as an epoxy resin or a bismaleimide triazine resin in the through hole 7. The hole-filling resin 8 is for making it possible to form a build-up insulating layer 1b directly above and below the through-hole 7 by closing the through-hole 7, and an uncured paste-like thermosetting resin is used. The through hole 7 is formed by filling the through hole 7 by screen printing and thermally curing it, and then polishing the upper and lower surfaces thereof substantially flatly. The insulating layer 1b is laminated on the upper and lower surfaces of the insulating layer 1a including the hole filling resin 8.

  The insulating layer 1b laminated on the upper and lower surfaces of the insulating layer 1a has a thickness of about 20 to 50 μm and a plurality of through holes (hereinafter referred to as via holes) 9 having a diameter of about 30 to 100 μm from the upper surface to the lower surface of each layer. have. These insulating layers 1b are provided to provide an insulating interval for wiring the plurality of wiring conductor layers 2 with high density, and the insulating layer 1b has vias in the wiring conductor layers 2 and via holes 9 on the surface thereof. A conductor 4 is formed. The upper wiring conductor layer 2 and the lower wiring conductor layer 2 are electrically connected via the via conductor 4 in the via hole 9 so that a high-density wiring can be formed in three dimensions.

  Such an insulating layer 1b is obtained by sticking an uncured thermosetting resin film having a thickness of about 20 to 50 μm to the upper and lower surfaces of the insulating layer 1a, thermosetting it, and drilling the via hole 9 by laser processing, Further, the next insulating layer 1b is sequentially stacked thereon in the same manner. The wiring conductor layer 2 formed on the surface of each insulating layer 1b and the via conductor 4 formed in the via hole 9 are added to the surface of each insulating layer 1b and the via hole 9 every time each insulating layer 1b is formed. It is formed by depositing a copper plating film having a thickness of about 50 μm in a predetermined pattern by a known pattern forming method such as a semi-additive method or a subtractive method.

  Further, in this example, the solder resist layer 10 is deposited on the outermost insulating layer 1b. The solder resist layer 10 is made of an insulating material in which an inorganic powder filler such as silica or talc is dispersed in an acrylic-modified epoxy resin, for example, and has an electrical insulation reliability between the outermost wiring conductor layers 2. It works to increase.

  Such a solder resist layer 10 has a thickness of about 10 to 50 μm, and an uncured resin paste for the solder resist layer 10 having photosensitivity is applied to the outermost insulating layer by using a roll coater method or a screen printing method. It is formed by applying on 1b and drying it, then performing exposure and development processes to form openings for exposing the electronic component connection pads 5 and external connection pads 6, and then thermally curing them. Alternatively, after an uncured resin film for the solder resist layer 10 is stuck on the uppermost insulating layer 1b, this is thermally cured, and then the positions corresponding to the electronic component connection pads 5 and the external connection pads 6 Are formed so as to have openings for exposing the electronic component connection pads 5 and the external connection pads 6 by partially removing the cured resin film.

  The wiring conductor layer 2 formed on the surfaces of the insulating layers 1a and 1b of the insulating substrate 1 is used to connect each electrode (signal, ground and power supply electrode) of the electronic component E such as a semiconductor element to an external electric circuit board (not shown). ) Function as a conductive path for electrical connection, and corresponding to each electrode of the electronic component E, the signal wiring conductor layer 2 (S), the ground wiring conductor layer 2 (G), and the power supply Each has a wiring conductor layer 2 (P), and a part of the wiring conductor layer 2 provided on the surface of the outermost insulating layer 1 b on the upper surface side of the insulating substrate 1 serves as an electrode of an electronic component E such as a semiconductor element. An electronic component connection pad 5 electrically connected via the solder bump B is formed, and a part of the wiring conductor layer 2 provided on the surface of the outermost insulating layer 1b on the lower surface side of the insulating substrate 1 is externally provided. Electricity is supplied to an electric circuit board (not shown) via external connection terminals T such as solder balls External connection pads 6 that are connected to each other are formed, and these electronic component connection pads 5 and external connection pads 6 are formed between the wiring conductor layer 2 and the through-hole conductors 3 provided between the upper and lower surfaces of the insulating substrate 1. They are electrically connected to each other via via conductors 4. The electronic component connection pad 5 and the external connection pad 6 also correspond to the wiring conductor layer 2 connected to them, and the signal electronic component connection pad 5 (S) and the grounding electronic component connection pad 5 (G). And a power supply electronic component connection pad 5 (P), a signal external connection pad 6 (S), a ground external connection pad 6 (G), and a power supply external connection pad 6 (P). .

  The signal wiring conductor layer 2 (S) is a thin strip pattern for propagating a high-speed electric signal having a frequency of about 100 M to 10 GHz between the electronic component E to be mounted and an external electric circuit board (not shown). For example, between the outermost insulating layer 1 b and the next insulating layer 1 b on the upper surface side of the insulating substrate 1. One end of the belt-like pattern is connected to a signal electronic component connection pad 5 provided on the surface of the outermost insulating layer 1b through a via conductor 4 penetrating the outermost insulating layer 1b on the upper surface side of the insulating substrate 1. The other end is connected to the lower surface side of the insulating substrate 1 via the via conductor 4 provided in the insulating layer 1b below the band-like pattern and the through-hole conductor 3 provided in the insulating layer 1a. It is electrically connected to a signal external connection pad 6 (S) provided on the surface of the outermost insulating layer 1b.

  The ground wiring conductor layer 2 (G) is two-dimensional in order to supply a ground potential to the electronic component E to be mounted and to provide an electromagnetic shield function and a characteristic impedance adjustment function for the signal wiring conductor layer 2 (S). A wide-area conductor plane extending with a general spread is provided on the surface of the outermost insulating layer 1b and the lower surface of the insulating layer 1a on the upper surface side and the lower surface side of the insulating substrate 1, for example. Among these, a part of the grounding wiring conductor layer 2 (G) formed on the surface of the outermost insulating layer 1 b on the upper surface side of the insulating substrate 1 is exposed from the solder resist layer 10 and connected to the grounding electronic component. A pad 5 (G) is formed, and a part of the ground wiring conductor layer 2 (G) formed on the surface of the outermost insulating layer 1 b on the lower surface side of the insulating substrate 1 is exposed from the solder resist layer 10. Thus, an external connection pad 6 (G) for grounding is formed. And they are electrically connected to each other through a through-hole conductor 3 provided in the insulating layer 1a and a via conductor 4 provided in the insulating layer 1b. The surface of the outermost insulating layer 1b on the upper surface side and the lower surface side of the insulating substrate 1 and the ground wiring conductor layer 2 (G) composed of the conductor plane extending on the lower surface of the insulating layer 1a are on the same surface. At positions where the signal and power wiring conductor layers 2 (S) and 2 (P) are present, the wiring conductor layers 2 (S) and 2 (P) are extended with a clearance surrounding the wiring conductor layers 2 (S) and 2 (P) at a predetermined interval. Exist.

  The power supply wiring conductor layer 2 (P) is two-dimensional in order to supply a power supply potential to the mounted electronic component E and to provide an electromagnetic shielding function and a characteristic impedance adjustment function for the signal wiring conductor layer 2 (S). For example, a conductor plane having a wide area extending with a general spread is provided between the outermost insulating layer 1b and the next insulating layer 1b on the upper surface of the insulating layer 1a and the lower surface side of the insulating substrate 1, for example. . Among these, the power supply wiring conductor layer 2 (P) formed on the upper surface of the insulating layer 1 a is connected to the power supply electronic component connection pad 5 (P) via the via conductor 4 penetrating the insulating layer 1 b above it. A part of the wiring conductor layer 2 (P) provided between the outermost insulating layer 1 b and the next insulating layer 1 b on the lower surface side of the insulating substrate 1 is an external connection pad 6 for power supply. (P) is formed. And they are electrically connected to each other through a through-hole conductor 3 provided in the insulating layer 1a and a via conductor 4 provided in the insulating layer 1b. In addition, the wiring conductor layer 2 (P) for power supply composed of a conductor plane extending between the outermost insulating layer 1b and the next insulating layer 1b on the upper surface of the insulating layer 1a and the lower surface side of the insulating substrate 1 is: At positions where the signal and ground wiring conductor layers 2 (S) and 2 (G) are present on the same surface, a clearance surrounding the wiring conductor layers 2 (S) and 2 (G) at a predetermined interval is provided. Have and extend.

  In the present invention, the outermost insulating layer 1b on the lower surface side of the insulating substrate 1 is formed with an opening A that exposes a part of the power supply wiring conductor layer 2 (P) provided on the inner side of the insulating layer 1b. The power supply wiring conductor layer 2 (P) exposed in the opening A forms a power supply external connection pad 6 (P). In this manner, the power supply external connection pad 6 (P) is formed in the power supply wiring conductor layer 2 (P) inside the opening A provided in the outermost insulating layer 1 b on the lower surface side of the insulating substrate 1. Compared with the case where the external connection pad 6 (P) for power supply is provided on the surface of the outermost insulating layer 1 b on the lower surface side of the insulating substrate 1 because it is formed by exposing a part. The number of via conductors 4 for connecting the electronic component connection pads 5 (P) and the external connection pads 6 (P) can be reduced by one layer of the insulating layer 1b. Accordingly, the inductance in the electrical path between the electronic component connection pad 5 (P) for power supply and the external connection pad 6 (P) can be reduced by that much, so that the electronic mounted on the wiring board can be reduced. Even when a high-speed signal of 3 GHz or more is input / output to / from the component E, it is possible to provide a wiring board that generates less noise in the signal and can normally operate the mounted electronic component E.

  At this time, when the wiring conductor layer 2 (P) forming the external connection pad 6 (P) for power supply is a conductor plane extending with a two-dimensional extension between the insulating layers 1 b, this conductor plane Thus, the inductance in the electrical path between the power supply electronic component connection pad 5 (P) and the external connection pad 6 (P) can be further reduced. Therefore, the wiring conductor layer 2 (P) forming the external connection pad 6 (P) for power supply is preferably a conductor plane extending with a two-dimensional extension between the insulating layers 1 b.

  A part of the power supply conductor layer 2 (P) provided on the outermost insulating layer 1 b on the lower surface side of the insulating substrate 1 is used as a power supply external connection pad 6 (P). In order to form the opening A to be exposed, as shown in FIG. 2A, after forming the solder resist layer 10 on the surface of the outermost insulating layer 1b, as shown in FIG. A method of chemically or physically removing the resin residue remaining on the surface of the external connection pad 6 (P) for power supply after laser processing is performed on the lowermost insulating layer 1b on the lower surface side of the substrate 1 and the opening A is formed. Is adopted.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, an external connection for a power source is possible. A wiring conductor layer 2 (P) for forming the pad 6 (P) is provided between the outermost insulating layer 1 b and the next insulating layer 1 b on the lower surface side of the insulating substrate 1, and a part thereof is the outermost layer. Although an example in which the external connection pad 6 (P) for power supply is formed by exposing it in the opening A provided in the insulating layer 1b is shown, the wiring conductor layer 2 (G) for grounding and the power supply in the above example are shown. The wiring conductor layer 2 (P) is replaced with the wiring conductor layer 2 (G) for forming the external connection pad 6 (G) for grounding with the outermost insulating layer 1 b on the lower surface side of the insulating substrate 1. Provided between it and the next insulating layer 1b, and part of it is provided on the outermost insulating layer 1b. Was by exposed in the opening A may be configured to form an external connection pad 6 (G) for grounding. Further, the electronic component connection pads 5 (G) and 5 (P) for grounding or power supply may be formed in the electronic component connection pads 5 with the same configuration.

It is a cross-sectional schematic diagram which shows one example of embodiment of the wiring board of this invention. (A), (b) is a cross-sectional schematic diagram for demonstrating the manufacturing method of the wiring board shown in FIG. It is a cross-sectional schematic diagram which shows the conventional wiring board.

Explanation of symbols

1: Insulating substrate 1a, 1b: Insulating layer 2: Wiring conductor layer 2 (S): Wiring conductor layer for signals 2 (G): Wiring conductor layer for grounding 2 (P): Wiring conductor layer for power supply 3: Through conductor (through hole conductor)
4: Through conductor (via conductor)
5: Electronic component connection pad 5 (S): Signal electronic component connection pad 5 (G): Ground electronic component connection pad 5 (P): Power supply electronic component connection pad 6: External connection pad 6 (S ): External connection pad for signal 6 (G): External connection pad for grounding 6 (P): External connection pad for power supply A: Opening provided in insulating layer 1b

Claims (2)

  An insulating substrate formed by laminating a plurality of insulating layers, a wiring conductor layer disposed between the surface of the insulating substrate and each insulating layer, and penetrating each of the insulating layers, and connecting the upper and lower wiring conductor layers to each other A signal conductor, a grounding and a power supply electronic component connection pad formed of a part of the wiring conductor layer on the upper surface of the insulating substrate, and the lower surface of the insulating substrate A wiring board comprising signal wiring, grounding and power supply external connection pads formed of a part of the wiring conductor layer electrically connected to the electronic component connection pad via the wiring conductor layer and the through conductor One of the external connection pads for grounding or power supply exposes a part of the wiring conductor layer inside the insulating layer in an opening provided in the insulating layer on the outermost layer on the lower surface side. By forming Wiring board, characterized by being.   2. The wiring according to claim 1, wherein the wiring conductor layer forming the external connection pad for grounding or power supply is a conductor plane extending two-dimensionally between the insulating layers. substrate.

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