JP4360617B2 - Wiring board - Google Patents

Description

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

  In general, along with the demand for downsizing and thinning of electronic devices such as mobile communication devices, wiring boards for mounting electronic components such as semiconductor elements used in such electronic devices are also small. There is a demand for reduction in size, thickness, and number of terminals. As a wiring board for realizing such miniaturization, thinning, and multi-terminal, for ball grid array packages (BGA) and chip scales that can be surface-mounted on the external electric circuit board via solder bumps. A wiring board for a package (CSP) has been put into practical use.

  Such a BGA or CSP wiring board is provided with an electronic component connection pad on which an electrode of an electronic component is connected via solder on the upper surface of an insulating substrate in which a plurality of insulating layers are stacked. An external connection pad connected to the wiring conductor of the external electric circuit board via solder is provided on the lower surface of the board. A wiring conductor for electrically connecting the electronic component connecting pad and the external connecting pad extends vertically through the insulating layer of the insulating substrate and extends horizontally between the insulating layers. Has been.

  And according to such a wiring board, it becomes an electronic device by mounting an electronic component on an insulating substrate so that its electrode is connected to an electronic component connecting pad via solder. The external connection pads are connected to the wiring conductors of the external electric circuit board via solder to be mounted on the external electric circuit board and the electronic components to be mounted are electrically connected to the external electric circuit; Become.

  Wiring conductors in such a wiring board are functionalized into wiring conductors for signals, grounds, and power supplies depending on applications.

  Among these, the signal wiring conductor functions as a conductive path for propagating an electric signal between an electronic component such as a semiconductor element and the external electric circuit board, and the insulating layer is directed from the central portion to the outer peripheral portion of the insulating substrate. A plurality of thin strip-shaped wiring conductors extending so as to increase the distance between each other, and the upper and lower wiring conductors are connected to each other by a through conductor penetrating the insulating layer, and further, by the through conductor penetrating the insulating layer It is connected to a signal electronic component connection pad and an external connection pad.

  In addition, the wiring conductor for grounding and the wiring conductor for power supply function as a supply path for supplying the ground potential and the power supply potential to the electronic components mounted on the wiring board, respectively, and the signal wiring It has an electromagnetic shielding function for the conductor and a characteristic impedance adjustment function, and an end portion between the signal conductor layers between the outer peripheral portion and the central portion between the insulating layers where the signal wiring conductors are formed. A large-area conductor layer and a large-area conductor layer arranged so as to face the signal wiring conductor across the insulating layer and extending through the insulating layer The through-conductors are connected to the grounding and power supply electronic component connection pads and the external connection pads, respectively.

In such a wiring board, the signal wiring conductor may be formed between the upper and lower insulating layers sandwiching the same insulating layer from the center to the outer periphery.
JP-A-11-135676

  Recently, however, the number of signal wiring conductors has increased with the high integration of semiconductor elements, etc., and the signal board at the center of each insulating layer has become smaller and more dense with the wiring board. The interval between adjacent wiring conductors is becoming narrower. Therefore, between the insulating layer where the signal wiring conductor is formed and extending from the outer periphery to the center with an end between the signal conductor layers, the grounding or power supply When the conductor layer is formed, the distance between the signal wiring conductors is narrow in the central region of the insulating layer, and there is no room for the wiring conductor for grounding or power supply to enter. In some cases, it can only enter partway between signal wiring conductors. In that case, a portion where the grounding or power supply conductor layer does not exist is formed in the central portion where the signal wiring conductor exists between the insulating layers.

  Then, among the upper and lower insulating layers sandwiching the same insulating layer, a plurality of signal wiring conductors are formed between the insulating layers between the central portion and the outer peripheral portion so that the distance between them is increased. In addition, a grounding or power supply conductor layer is formed partway between the signal wiring conductors from the outer peripheral portion of the interlayer toward the central portion, and the central portion is interposed between the other insulating layers. When a wiring conductor for propagating high-frequency signals from the outer periphery to the outer periphery is formed, the signal wiring conductor formed between the other insulating layers is used for grounding between the other insulating layers. Alternatively, the power supply conductor layer and the insulating layer are not opposed to each other at the central portion, but are opposed to each other at the outer peripheral portion, and are opposed to the portion that is not opposed to the grounding or power supply conductor layer formed between the insulating layers. And its characteristics Dance would change. When a high frequency signal of, for example, 5 GHz or more is propagated to a wiring conductor whose characteristic impedance changes midway in this way, signal reflection or attenuation occurs, and normality of the high frequency signal propagating through the signal wiring conductor due to the reflection or attenuation is caused. Therefore, there is a problem that electronic components such as semiconductor elements mounted on the wiring board cannot be normally operated due to hindered propagation.

  The present invention has been completed in view of such conventional problems, and the object thereof is to provide an outer peripheral portion from the central portion between the insulating layers between the upper and lower insulating layers sandwiching the same insulating layer. A plurality of signal wiring conductors are formed so as to extend toward each other, and the grounding or power supply is partway between the signal wiring conductors from the outer peripheral portion to the center portion between the layers. Is formed between the other insulating layers in a wiring board on which a wiring conductor for propagating a high-frequency signal is formed between the other insulating layer and the center to the outer periphery. Even when a high-frequency signal having a frequency of 5 GHz or more is propagated through the signal wiring conductor, no signal reflection or attenuation occurs in the signal wiring conductor. Good high-frequency signal Is sown, it is to provide a wiring substrate capable of successfully operating the electronic components mounted.

Wiring board of the present invention, an insulating layer, a plurality of first signal wiring conductor having a region extending the distance therebetween toward the outer periphery from the central portion on one main surface of the insulating layer, the insulating layer The grounding or power supply conductor layer formed on the one main surface and between the first signal wiring conductors to the middle from the outer periphery to the center of the one main surface , and the insulation A second signal wiring conductor formed on the other main surface of the layer from the central portion to the outer peripheral portion, and the second signal wiring conductor provided on the other main surface of the insulating layer The conductive layer and the first signal wiring conductor provided on the one main surface of the insulating layer are arranged so as not to overlap in plan view .

  The wiring board of the present invention includes an insulating layer, a plurality of first wiring conductors formed on one main surface of the insulating layer so that a distance from the central portion toward the outer peripheral portion increases, and the one A grounding or power supply conductor layer formed partway from the outer peripheral portion of the one main surface toward the central portion at a portion between the first wiring conductors of the main surface of the main surface, and the other of the insulating layers A second wiring conductor formed on the main surface from the central portion to the outer peripheral portion, and the conductor layer does not exist in a portion facing the second wiring conductor on the one main surface. The second wiring conductor does not entirely face the conductor layer, so that the characteristic impedance is kept constant. Therefore, even when a high-frequency signal having a frequency of 5 GHz or more is propagated to the second wiring conductor, no signal reflection or attenuation occurs in the second wiring conductor, and the second wiring conductor has a high frequency. Thus, it is possible to provide a wiring board in which the above-mentioned signal is propagated satisfactorily and the mounted electronic component can be operated normally.

  Next, the wiring board of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example in which the best mode for carrying out the present invention is applied to a wiring board for mounting a semiconductor element, in which 1 is an insulating substrate, 2a, 2b, 2c is an electronic component connection pad for signal, grounding and power supply, 3a, 3b and 3c are external connection pads for signal, grounding and power supply, and 4a, 4b and 4c are for signal and grounding, respectively. Wiring conductor for power and power supply.

  In this example, the insulating substrate 1 is formed by laminating three insulating layers 1b made of thermosetting resin on the upper and lower surfaces of the insulating layer 1a made by impregnating glass fabric with thermosetting resin, The outermost insulating layer 1b is a solder resist layer. Also, signal, grounding and power supply electronic component connection pads 2a, 2b and 2c are formed on the upper surface of the insulating substrate 1, and signals, grounding and power supply are formed on the lower surface of the insulating substrate 1, respectively. External connection pads 3a, 3b, 3c are arranged in rows and columns, and corresponding electronic component connection pads 2a, 2b, 2c and external connection pads 3a, 3b are arranged from the upper surface to the lower surface of the insulating substrate 1, respectively. Wiring conductors 4a, 4b, and 4c for signal, grounding, and power supply that electrically connect 3b and 3c to each other are disposed.

  The insulating layer 1a is a member that becomes the core of the wiring board of this example, and is formed by impregnating a glass fabric in which glass fiber bundles are woven vertically and horizontally with a thermosetting resin such as epoxy resin or bismaleimide triazine resin, The thickness is about 0.3 to 1.5 mm, and a plurality of through holes 5 having a diameter of about 0.1 to 1 mm are provided from the upper surface to the lower surface. The upper and lower surfaces of the conductor layers 4a, 4b, and 4c are covered with a conductor layer that is a part of the wiring conductors 4a and 4c, and cylindrical through conductors are attached to the inner surfaces of the through holes 5. The layers are electrically connected via a through conductor in the through hole 5.

  Such an insulating layer 1a is manufactured by thermally curing an insulating sheet in which a glass fabric is impregnated with an uncured thermosetting resin, and then drilling the insulating sheet from the upper surface to the lower surface. In addition, the conductor layers on the upper and lower surfaces of the insulating layer 1a are obtained by attaching a copper foil having a thickness of about 3 to 50 μm to the entire upper and lower surfaces of the insulating sheet for the insulating layer 1a and etching the copper foil after the sheet is cured. Thus, a predetermined pattern is formed. Further, the through conductor on the inner surface of the through hole 5 is provided with a through hole 5 in the insulating layer 1a, and then a copper plating film having a thickness of about 3 to 50 μm is deposited on the inner surface of the through hole 5 by an electroless plating method and an electrolytic plating method. Is formed.

  Furthermore, the insulating layer 1a is filled with a resin column 6 made of a thermosetting resin such as an epoxy resin or a bismaleimide triazine resin in the through hole 5 thereof. The resin pillar 6 is for making it possible to form each insulating layer 1b directly above and below the through-hole 5 by closing the through-hole 5, and an uncured paste-like thermosetting resin is placed in the through-hole 5 After the film is filled by screen printing and thermally cured, the upper and lower surfaces thereof are polished substantially flatly. Three insulating layers 1b are laminated on the upper and lower surfaces of the insulating layer 1a including the resin pillars 6 respectively.

  Each insulating layer 1b laminated on the upper and lower surfaces of the insulating layer 1a has a thickness of about 20 to 60 μm, and has a plurality of through holes 7 having a diameter of about 30 to 100 μm from the upper surface to the lower surface of each layer. . Each of these insulating layers 1b is for providing an insulating interval for wiring the wiring conductors 4a, 4b, 4c with high density, and on the surface of each insulating layer 1b except the outermost insulating layer 1b. A conductor layer that constitutes a part of the wiring conductors 4 a, 4 b, 4 c is deposited and a through conductor is deposited in the through hole 7. The upper conductor layer and the lower conductor layer are electrically connected via the through conductor in the through hole 7 to enable three-dimensional high-density wiring. Each of such insulating layers 1b has an insulating film made of an uncured thermosetting resin having a thickness of about 20 to 60 [mu] m attached to the upper and lower surfaces of the insulating layer 1a, thermally cured, and laser-processed through-holes. 7 is drilled, and the next insulating resin layers are sequentially stacked thereon in the same manner. The conductive layer on the surface of each insulating layer 1b and the through conductor in the through hole 7 are formed of copper having a thickness of about 5 to 50 μm on the surface of each insulating layer 1b and in the through hole 7 each time each insulating layer 1b is formed. It is formed by depositing a plating film in a predetermined pattern by a pattern forming method such as a known semi-additive method or subtractive method.

  Also, the electronic component connection pads 2a, 2b, 2c formed on the upper surface of the insulating substrate 1 and the external connection pads 3a, 3b, 3c formed on the lower surface of the insulating substrate 1 are copper having a thickness of about 3 to 50 μm. It consists of a plating film and functions as a connection electrode for electrically connecting the electrodes of the electronic component and the wiring conductor of the external electric circuit board to the wiring conductors 4a, 4b, 4c, respectively. Solder 8a, 8b is bonded to each exposed surface, and each electrode of the electronic component is connected to the electronic component connecting pads 2a, 2b, 2c via the solder 8a, and the external connecting pad 3a, A wiring conductor of an external electric circuit board is connected to 3b and 3c via solder 8b. Such electronic component connection pads 2a, 2b, 2c and external connection pads 3a, 3b, 3c are coated with a copper plating film in a predetermined pattern on the surface of the insulating layer 2b by a known semi-additive method or subtractive method. The solder 8a and 8b are joined by applying a solder paste to the surface and reflowing it. The electronic component connection pads 2a, 2b and 2c are circular with a diameter of about 50 to 100 μm, and the external connection pads 3a, 3b and 3c are circular with a diameter of about 200 to 500 μm.

  These electronic component connection pads 2a, 2b and 2c are connected to the external connection pads 3a, 3b and 3c so as to be connected from the upper surface to the lower surface of the insulating substrate 1 for signal, grounding and power supply. Each wiring conductor 4a, 4b, 4c functions as a conductive path for connecting each electrode of the electronic component to the external electric circuit board, and a wiring conductor pattern corresponding to each function for each layer of the insulating layer 1b. It is arrange | positioned so that it may have.

  In the wiring board of this example, for example, as shown in the plan view of the main part in FIG. 2, there is a signal wiring conductor 4a between the central portion and the outer peripheral portion of the insulating layer 1b between the insulating layers 1b. A plurality of thin strip-shaped first wiring conductors 4a1 extending so as to increase the distance from each other are formed, and as a part of the grounding wiring conductor 4b, from the outer peripheral portion toward the central portion of the insulating layer 1b. A conductor layer 4b1 extending partway between the first wiring conductors 4a1 is formed. The first wiring conductor 4a1 is a transmission line for signals, and is formed in the central portion of the upper surface of the insulating substrate 1 by being formed so that the distance from each other increases from the central portion of the insulating substrate 1 toward the outer peripheral portion. The signal electronic component connection pad 2a and the signal external connection pad 3a formed on the outer periphery of the lower surface of the insulating substrate 1 can be connected. The conductor layer 4b1 functions to reinforce the electromagnetic shield of the first wiring conductor 4a1 by supplying a grounding potential stably and extending between the first wiring conductors 4a1.

  Further, as shown in a plan view of the main part in FIG. 3, as a part of the signal wiring conductor 4a, the insulating layer 1b on which the first wiring conductor 4a1 and the conductor layer 4b1 are formed is interposed between the layers. A thin strip-shaped second wiring conductor 4a2 extending from the central portion of the insulating layer 1b toward the outer peripheral portion is formed. The second wiring conductor 4a2 is a conductive path for propagating a high frequency signal. For example, a high frequency signal of 5 GHz or more is propagated.

  2 and 3, the upper side indicates the outer peripheral side of the insulating substrate 1, and the lower side indicates the central side of the insulating substrate 1. 2 and 3 are main part plan views of the same part of the wiring board of this example as viewed from the same side. For the sake of simplicity, the first wiring conductor 4a1 and the conductor layer are shown as wiring conductors in FIG. Only 4b1 is shown, and only the second wiring conductor 4a2 is shown in FIG.

  In the wiring board of this example, as shown in FIG. 2, the conductor layer 4b1 is provided with a notch C where the conductor layer 4b1 does not exist at a portion facing the second wiring conductor 4a2. As described above, the conductor layer 4b1 is formed with the notched portion C where the conductor layer 4b1 does not exist in a portion corresponding to the second wiring conductor 4a2. As shown in FIG. 4, which is a diagram, the second wiring conductor 4a2 does not entirely face the conductor layer 4b1, and therefore the characteristic impedance of the second wiring conductor 4a2 is kept constant. Therefore, even when a high-frequency signal having a frequency of 5 GHz or more is propagated to the second wiring conductor 4a2, no signal reflection or attenuation occurs in the second wiring conductor 4a2, and the second wiring conductor 4a2. It is possible to provide a wiring board in which a high-frequency signal can be satisfactorily propagated to 4a2 and a mounted electronic component can be operated normally. When the width of the notch C is less than 10 μm on one side than the width of the second wiring conductor 4a2, the electromagnetic coupling between the second wiring conductor 4a2 and the conductor layer 4b1 is large. This increases the risk that the characteristic impedance of the second wiring conductor 4a2 becomes non-uniform. Therefore, the width of the notch C is preferably 10 μm or more on both sides than the width of the second wiring conductor 4a2, and more preferably wider than the width of the second wiring conductor 4a2 on both sides.

  Thus, according to the wiring board of the present invention, the electronic component is mounted on the upper surface of the insulating substrate 1 so that the electrode thereof is connected to each of the electronic component connecting pads 2a, 2b, 2c via the solder 8a. The electronic device is mounted on the external electric circuit board and mounted on the electronic device by connecting the external connection pads 3a, 3b, 3c to the wiring conductor of the external electric circuit board via the solder 8b. Each electrode of the component is electrically connected to an external electric circuit.

  It should be noted that 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 conductor layer 4b1 is formed. Although an example of a grounding conductor layer has been shown, this conductor layer may be a power source conductor layer.

It is sectional drawing which shows the example of the best form for implementing the wiring board of this invention. It is a principal part top view which shows the interlayer of one insulating layer of the wiring board of this invention. FIG. 3 is a plan view of a principal part showing an interlayer of a next insulating layer shown in FIG. 2. FIG. 4 is a perspective view of FIG. 3 superimposed on FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b: Insulating layer 4a1: 1st wiring conductor 4b1: Conductive layer for earth | ground or power supply 4a2: 2nd wiring conductor

Claims (3)

An insulating layer;
A plurality of first signal wiring conductors having a region in which one of the main surfaces of the insulating layer has an interval that increases from the central portion toward the outer peripheral portion;
A grounding or power supply conductor layer formed on the one main surface of the insulating layer and at a position between the first signal wiring conductors from the outer peripheral portion to the middle portion of the one main surface. When,
A second signal wiring conductor formed on the other main surface of the insulating layer from the center to the outer periphery;
It has
The second signal wiring conductor provided on the other main surface of the insulating layer overlaps the conductor layer and the first signal wiring conductor provided on the one main surface of the insulating layer in plan view. A wiring board characterized in that the wiring board is arranged so as not to occur . The wiring board according to claim 1,
  Of the one main surface of the insulating layer, when a portion facing the second signal wiring conductor is a facing region,
The wiring board according to claim 1, wherein the conductor layer has an extending portion formed from an outer peripheral portion of the one main surface toward a central portion between the first signal wiring conductor and the opposing region. The wiring board according to claim 1;
Electronic components mounted on the wiring board;
An electronic device comprising:

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