JP5370883B2 - Wiring board - Google Patents

Description

  The present invention relates to a wiring board used for mounting an electronic component such as a semiconductor element, and more specifically, a wiring having a connector connecting portion to which a coaxial connector for inputting and outputting a high-frequency signal to and from the mounted electronic component is connected. Regarding the substrate.

  2. Description of the Related Art Conventionally, a wiring board used for mounting electronic components that operate at high frequencies such as semiconductor elements has a plurality of insulating layers made of an electrically insulating material containing a thermosetting resin such as an epoxy resin as shown in FIG. A plurality of conductor layers 32 made of a metal film such as a copper foil or a copper plating layer are disposed on the surface of the insulating substrate 31 and between the insulating layers, and an electronic component E is flip-chip mounted on the center of the upper surface. In addition, a connector connecting portion 33 to which a coaxial connector for taking in and out a high frequency signal is connected is provided on the outer peripheral portion thereof. Further, the solder resist layer 34 covers the upper surface excluding the connection portion with the electronic component E and the connector connection portion 33. The connection portion with the electronic component E and the connector connection portion 33 are connected by a coplanar line with a ground, and a high-frequency signal is input / output between the outside and the electronic component E via the coplanar line with a ground. The electronic component E is actuated by In this figure, only two conductor layers 32 are shown for simplification, but actually a plurality of conductor layers 32 are further provided. Furthermore, in order to facilitate understanding of the arrangement of the conductor layer 32, the conductor layer 32 is shown exposed on the outer peripheral side surface of the insulating substrate 31. It is arranged in an inner region of about several hundred μm to several mm.

As shown in the enlarged perspective view of the main part in FIG. 8, the connector connecting portion 33 is formed on the upper surface of the outermost insulating layer 31b so as to extend from the outer peripheral portion of the insulating substrate 1 to the connecting portion with the electronic component E. A thin strip-shaped signal line 32 (S), a first grounding conductor 32 (G1) deposited on both sides of the signal line 32 at a predetermined interval, and a signal line across the outermost insulating layer 31b 32 (S) and the second ground conductor 32 (G2) opposite to the first ground conductor 32 (G1), and the first end of the signal line 32 (S) and the periphery thereof. The ground conductor 32 (G1) is formed by exposing it from the solder resist layer 34. The first ground conductor 32 (G1) and the second ground conductor 32 (G2) are electrically connected to each other by a via conductor 35 that penetrates the outermost insulating layer 31b. Then, the signal pin 41 of the coaxial connector 40 is connected to the signal line 32 (S) exposed at the connector connecting portion 33 and the coaxial connector 40 is grounded to the first ground conductor 32 (G1) exposed at the connector connecting portion 33. The metal fitting 42 is connected, and the high frequency signal is input / output through the coaxial connector 40 connected to the connector connecting portion 33.
JP 2003-258142 A

  However, according to this conventional wiring board, the grounding fitting 42 of the coaxial connector 40 is directly connected only to the first grounding conductor 32 (G1), and the first grounding conductor 32 (G2) is connected to the first grounding conductor 32 (G2). The conductor 32 (G1) and the second ground conductor 32 (G2) are electrically connected via a via conductor 35. Since the via conductor 35 has a diameter of about 30 to 100 μm and acts as an inductance component of about several tens of pH per piece, the first portion from the grounding fitting 42 of the coaxial connector 40 to the connection portion with the electronic component E is accordingly provided. The inductance in the electrical path that combines the second ground conductor 32 (G1) and the second ground conductor 32 (G2) is increased. When the inductance in the electrical path combining the first ground conductor 32 (G1) and the second ground conductor 32 (G2) is high, the electronic component E mounted on the wiring board is passed through the coaxial connector 40 to, for example, 3 GHz or more. When a high-speed signal is taken in and out, noise called ringing noise is generated in the signal, and it becomes difficult to normally operate the electronic component E to be mounted.

  The present invention has been devised in view of such conventional problems, and the purpose of the present invention is that even if a high-speed signal of 3 GHz or more is input / output to / from an electronic component mounted on a wiring board, noise is included in the signal. 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.

In the wiring board of the present invention, the first notch in which the coaxial connector is fitted to the outer peripheral portion of the insulating substrate formed by laminating a plurality of insulating layers including the outermost insulating layer having a thickness of 20 to 50 μm is the insulating layer. A signal line connected to a signal pin of the coaxial connector on the outermost insulating layer, and a first ground conductor disposed on both sides of the signal line, which is formed so as to penetrate the substrate Are formed so as to be led out to the periphery of the first notch, and are opposed to the signal line and the first ground conductor inside the insulating substrate with the outermost insulating layer interposed therebetween. A wiring board comprising a second ground conductor, wherein a part of the second ground conductor is exposed on both sides of the signal line in the outermost insulating layer around the first notch. together they have openings or second notches to the front The grounding fitting of the coaxial connector is provided with a protrusion that fits into the opening or the second cutout, and the protrusion is fitted into the opening or the second cutout to The first ground conductor and the second ground conductor are directly joined to each other.

According to the wiring board of the present invention, the opening that exposes part of the second ground conductor on both sides of the signal line in the outermost insulating layer in which the signal line and the first ground conductor are formed or the second ground conductor is provided. The grounding fitting of the coaxial connector is provided with a protrusion that fits into the opening or the second notch, and the grounding fitting is fitted into the opening or the second notch. Since the first ground conductor and the second ground conductor are directly joined , the coaxial connector grounding fitting is not only provided with the first ground conductor but also with the opening or second notch provided in the outermost insulating layer. The second grounding conductor exposed from can be directly joined without via conductors. Therefore, the inductance in the electrical path combining the first ground conductor and the second ground conductor from the grounding fitting of the coaxial connector to the connection portion with the electronic component can be reduced. 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 perspective 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 is a connector connecting portion, and 4 is a solder resist layer.

  As shown in FIG. 1, the wiring board of the present embodiment has a surface of an insulating substrate 1 formed by laminating a plurality of insulating layers made of an electrically insulating material containing a thermosetting resin such as an epoxy resin, and between each insulating layer. A plurality of conductor layers 2 made of a metal film such as a copper foil or a copper plating layer are disposed, and an electronic component E is flip-chip mounted at the center of the upper surface, and a high-frequency signal is taken in and out of the outer peripheral portion. A connector connecting portion 3 to which a coaxial connector is connected is provided. Further, the solder resist layer 4 covers the upper surface excluding the connection part with the electronic component E and the connector connection part 3. And the connection part with the electronic component E and the connector connection part 3 are connected by a coplanar line with a ground, and a high frequency signal is taken in and out between the outside and the electronic part through the coplanar line with a ground. By doing so, the electronic component E is operated. In this figure, only two conductor layers 2 are shown for simplification, but actually a plurality of conductor layers 2 are further provided. Further, in order to facilitate understanding of the arrangement of the conductor layer 2, the conductor layer 2 is shown exposed on the outer peripheral side surface of the insulating substrate 1, but actually the conductor layer 2 is exposed from the outer peripheral side surface of the insulating substrate 1. It is arranged in an inner region of about several hundred μm to several mm. Further, in this example, the case where only one connector connecting portion 3 is provided is shown, but actually, a plurality of similar connector connecting portions 3 may be provided.

  As shown in a sectional view in FIG. 2, the insulating substrate 1 includes 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 an epoxy resin or a bismaleimide triazine resin. A plurality of build-up insulating layers 1b made of a thermosetting resin such as epoxy resin or bismaleimide triazine resin are laminated on the upper and lower surfaces, respectively, and copper foil or copper plating is formed on the surface of each insulating layer 1a, 1b. A plurality of conductor layers 2 made of a conductor layer such as a film are formed, and a through conductor (hereinafter referred to as a through-hole conductor) 5 and each build-up insulation layer 1b are formed through the core insulation layer 1a. A through conductor (hereinafter referred to as a via conductor) 6 is formed so as to penetrate therethrough.

  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). The upper and lower surfaces are covered with the conductor layer 2 and the through hole conductor 5 is attached to the inner surface of each through hole 7. The upper and lower conductor layers 2 of the insulating layer 1 a are connected to the through holes. It is electrically connected via the conductor 5.

  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. The 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 adhered to the entire upper and lower surfaces of the sheet for the insulating layer 1a, and this copper foil is etched after the sheet is cured. By doing so, a predetermined pattern is formed. The through-hole conductor 5 on the inner surface of the through-hole 7 is a copper plating film having a thickness of about 5 to 50 μm formed by electroless plating and electrolytic plating on the inner surface of the through-hole 7 after the through-hole 7 is provided 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 for providing an insulating interval for wiring a plurality of conductor layers 2 with high density. The insulating layer 1b has a conductor layer 2 on its surface and via conductors 6 in the via holes 9. Is formed. The upper conductor layer 2 and the lower conductor layer 2 are electrically connected via the via conductor 6 in the via hole 9 so that a high-density wiring can be formed three-dimensionally.

  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 conductor layer 2 formed on the surface of each insulating layer 1b and the via conductor 6 formed in the via hole 9 are 5 to 50 μm in the surface of each insulating layer 1b and in the via hole 9 every time each insulating layer 1b is formed. It is formed by depositing a copper plating film of a certain thickness on a predetermined pattern by a pattern forming method such as a known semi-additive method or subtractive method.

  Further, in this example, the solder resist layer 4 is deposited on the outermost insulating layer 1b. The solder resist layer 4 is made of, for example, an insulating material in which an inorganic powder filler such as silica or talc is dispersed in an acrylic-modified epoxy resin by about 30 to 70% by mass, and improves the electrical insulation reliability between the outermost conductor layers 2. It works.

  Such a solder resist layer 4 has a thickness of about 10 to 50 μm, and an uncured resin paste for the solder resist layer 4 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 exposing and developing to form a predetermined opening, and then thermally curing it. Alternatively, after an uncured resin film for the solder resist layer 4 is stuck on the uppermost insulating layer 1b, it is thermally cured, and then the cured resin film is partially irradiated with laser light. By removing, it is formed to have a predetermined opening.

  The conductor layer 2 formed on the surface of each insulating layer 1a, 1b of the insulating substrate 1 electrically connects each electrode (signal, ground and power supply electrode) of the electronic component E to an external electric circuit substrate (not shown). A portion of the conductor layer 2 provided on the surface of the outermost insulating layer 1b on the upper surface side of the insulating substrate 1 has solder bumps B applied to electrodes of an electronic component E such as a semiconductor element. And a part of the conductor layer 2 provided on the surface of the outermost insulating layer 1b on the lower surface side of the insulating substrate 1 is formed on the external electric circuit board (not shown). External connection pads 12 are formed which are electrically connected to each other via external connection terminals T such as solder balls.

  Furthermore, a part of the conductor layer 2 provided on the surface of the outermost insulating layer 1b on the upper surface side of the insulating substrate 1 is used as a signal line 2 (S) having first ground conductors (not shown) on both sides thereof. A conductive path for connecting the electronic component connecting pad 11 and the connector connecting portion 3 is formed, and below the second ground conductor 2 (G2) facing the coplanar line is the outermost insulating layer 1b. It is arranged on both sides. The signal line 2 (S), the first ground conductor (not shown), and the second ground conductor 2 (G 2) are connected to the coaxial connector 20 at the connector connecting portion 3.

  As shown in the enlarged perspective view of the main part in FIG. 3, the connector connecting portion 3 is thinly formed on the upper surface of the outermost insulating layer 1 b so as to extend from the outer peripheral portion of the insulating substrate 1 to the electronic component connecting pad 11. The signal line 2 (S) sandwiched between the strip-shaped signal line 2 (S), the first ground conductor 2 (G1) deposited on both sides of the belt-like signal line 2 (S), and the outermost insulating layer 1b. ) And a second ground conductor 2 (G2) facing the first ground conductor 2 (G1), and the first ground conductor 2 at the end of the signal line 2 (S) and its periphery. It is formed by exposing (G1) from the solder resist layer 4. Further, the outermost insulating layer 1b is formed with notches C that expose the second ground conductor 2 (G2) on both sides of the signal line 2 (S).

  Then, as shown in the enlarged perspective view of the main part in FIG. 4, the signal pin 21 of the coaxial connector 20 is connected to the signal line 2 (S) exposed at the connector connecting portion 3 and the first exposed at the connector portion 3. A grounding fixture 22 of the coaxial connector 20 is connected to the grounding conductor 2 (G1) and the second grounding conductor 2 (G2), and a high-frequency signal is taken in and out through the coaxial connector 20 connected to the connector connecting portion 3. The grounding fitting 22 of the coaxial connector 20 is provided with a protrusion 22a that fits into the notch C so that the lower surface of the protrusion 22a abuts the exposed surface of the second grounding conductor 2 (G2). Keep it. At this time, the grounding fitting 22 of the coaxial connector 20 is not only applied to the first grounding conductor 2 (G1) but also to the second grounding conductor 2 (G2) exposed from the notch C provided in the outermost insulating layer 1b. Direct bonding can be performed without via via conductor 6. Therefore, the inductance in the electrical path combining the first ground conductor 2 (G1) and the second ground conductor 2 (G2) from the grounding fitting 22 of the coaxial connector 20 to the electronic component connection pad 11 is low. can do. As a result, even when a high-speed signal of 3 GHz or higher is input / output to / from the electronic component E mounted on the wiring board, the generation of noise in the signal is small, and the wiring that can operate the mounted electronic component E normally. A substrate can be provided.

  As shown in FIG. 5, the connector connecting portion 3 includes a signal line 2 (S) and a first ground conductor 2 (G1) formed on the insulating layer 1b on the upper surface side, and the connector connecting portion 3 The solder resist layer 4 is covered except for the region. At this time, the portion of the first ground conductor 2 (G1) that becomes the notch C is removed. Next, as shown in FIG. 6, a notch having a size with which a part of the grounding metal fitting 22 of the coaxial connector 20 is fitted into a part of a region to be the connector connecting portion 3 of the insulating base 1 is formed by a router. Finally, after removing the portion of the outermost insulating layer 1b which becomes the notch C by laser processing, the resin residue remaining on the surface of the second ground conductor 2 (G2) exposed in the notch C is chemically or A physical removal method is employed.

  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, the connector connection portion 3 can be changed. The notch C that exposes the second ground conductor 2 (G2) is provided in the outermost insulating layer 1b. However, not only the notch but also an opening that exposes the second ground conductor 2 (G2) may be provided. Good.

It is a schematic perspective view which shows one embodiment of the wiring board of this invention. It is a cross-sectional schematic diagram of the wiring board shown in FIG. It is a principal part expansion perspective view of the wiring board shown in FIG. It is a principal part expansion perspective view of the wiring board shown in FIG. FIG. 3 is an enlarged perspective view of a main part for explaining a method for manufacturing the wiring board shown in FIG. 1. FIG. 3 is an enlarged perspective view of a main part for explaining a method for manufacturing the wiring board shown in FIG. 1. It is a schematic perspective view which shows the conventional wiring board. It is a principal part expansion perspective view of the wiring board shown in FIG.

Explanation of symbols

1: Insulating substrate 1a, 1b: Insulating layer 2: Conductor layer 2 (S): Signal line 2 (G1): First ground conductor 2 (G2): Second ground conductor 3: Connector connecting portion 20: Coaxial Connector 21: Signal pin C of coaxial connector: Notch provided in outermost insulating layer 1b

Claims (1)

A first notch in which a coaxial connector is fitted to an outer peripheral portion of an insulating substrate formed by laminating a plurality of insulating layers including an outermost insulating layer having a thickness of 20 to 50 μm is formed so as to penetrate the insulating substrate. are, the outermost layer of the insulating layer, the first and ground conductor wherein said first switching signal pin of the coaxial connector is disposed on either side of the signal line and the signal for line connected A second grounding conductor is formed inside the insulating substrate, and the second grounding conductor facing the signal line and the first grounding conductor is interposed between the outermost insulating layers. A wiring board formed on the outermost insulating layer around the first notch, wherein an opening or a second notch that exposes a part of the second ground conductor on both sides of the signal line is provided. together we have outs, grounding of the coaxial connector The tool is provided with a protrusion that fits into the opening or the second notch, and the protrusion is fitted into the opening or the second notch to connect the grounding metal fitting and the first notch. A wiring board, wherein a ground conductor and the second ground conductor are directly joined .

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