JP4349891B2 - Wiring board and electronic device - 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. And having a plurality of thin strip-like wiring conductors extending in parallel so that the distance between them is increased, and the upper and lower wiring conductors are connected to each other by a through conductor that penetrates the insulating layer, and further penetrates the insulating layer. The through conductor is connected to the signal electronic component connection pad and the 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 a conductor and a characteristic impedance adjustment function, and has an end between parallel portions of signal wiring conductors formed in parallel and extends from the end to one side along the parallel portion. A conductor layer having a large area disposed so as to face the signal wiring conductor across the conductor layer and the insulating layer formed as described above, and a through conductor penetrating the insulating layer for grounding and power supply respectively. It is connected to the electronic component connecting pad and the external connecting pad.
JP-A-11-135676

  However, a conductor layer for grounding or power supply is formed so as to have an end portion between parallel portions of signal wiring conductors formed in parallel and to extend from the end portion to one side along the parallel portion. In this case, when a high-frequency signal having a frequency exceeding 10 GHz is propagated to the signal wiring conductor, an end portion is provided between the parallel portions of the parallel signal wiring conductors, and the end portion extends along the parallel portion. The extending conductor layer for grounding or power supply acts as a stub or branch, and resonance corresponding to the signal propagated through the wiring conductor for signal occurs in the conductor layer for grounding or power supply extending along this parallel part, Due to the resonance, the normal propagation of the signal propagating through the signal wiring conductor is hindered, and the electronic component such as a semiconductor element mounted on the wiring board cannot be normally operated.

  The present invention has been completed in view of such conventional problems, and its object is to be formed in parallel even if the frequency of the signal propagating through the signal wiring conductor is higher than 10 GHz. Resonance does not occur in the grounding or power supply conductor layer that has an end portion between the parallel portions of the signal wiring conductor and extends to one side along the parallel portion from the end portion. An object of the present invention is to provide a wiring board in which a high-frequency signal can be satisfactorily propagated to a wiring conductor and a mounted electronic component can be operated normally.

The wiring board of the present invention includes an insulating layer, a plurality of signal wiring conductors disposed on one main surface of the insulating layer, and two of the plurality of wiring conductors on the one main surface , extending from spacing one end of each other in the direction in which the gap widens along from the end portion to the parallel portion and having an end portion between the parallel portion formed in parallel so as to extend toward the other end, and A grounding or power supply first conductor layer formed so as to surround the periphery of the parallel part, and on the other main surface of the insulating layer, the grounding or facing at least the end part A second conductor layer for power supply is formed, and the second conductor layer and the end portion are electrically connected through a through conductor.
In the wiring board of the present invention, preferably, in the above configuration, the distance from the edge of the end portion to the through conductor is less than a quarter of the wavelength of the signal propagating through the signal wiring conductor. It is a feature.

  The electronic device according to the present invention is characterized in that an electronic component is mounted on the wiring board of the present invention, and an electrode of the electronic component and the signal wiring conductor are electrically connected.

  According to the wiring board of the present invention, one of the main surfaces of the insulating layer has an end portion between the parallel portions formed of two of the signal wiring conductors in parallel and from the end portion to the parallel portion. The first conductor layer for grounding or power supply formed to extend in one direction along the second conductor is a second conductor for grounding or power supply whose end is disposed on the other surface of the insulating layer. Since it is electrically connected to the layer via a through conductor, it does not act as a stub or branch, so even if a high-frequency signal exceeding 10 GHz is propagated to a signal wiring conductor The first conductor layer for grounding or power supply does not generate resonance corresponding to the signal, and as a result, the high-frequency signal is propagated well to the signal wiring conductor, and the mounted electronic component is normal. Can be operated. Further, when the first conductor layer is formed so as to surround the parallel portion, electromagnetic shielding of the signal wiring conductor is enhanced, and a high-frequency signal can be propagated more efficiently.

  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 an external electric circuit board. If the wiring conductor 4a is a signal, the main part is shown in FIG. As shown in the plan view, a plurality of thin strip-like wiring conductors 4a1 extending in parallel so that the distance between the insulating layers 1b increases from the central portion of the insulating substrate 1 toward the outer peripheral portion. In the case of the grounding wiring conductor 4b, the wiring conductor 4a1 has a first end formed so as to have an end portion between the parallel portions formed in parallel and extend from the end portion to one side along the parallel portion. As shown in the cross-sectional view of the main portion of the conductor layer 4b1 and the XX cutting line of FIG. 2A in FIG. 2B, the wiring conductor 4a1 and the first conductor layer 4b1 are opposed to each other with the insulating layer 1b interposed therebetween. The second conductor layer 4b2 is included. The signal wiring conductor 4a functions as a conductor for inputting and outputting signals to and from the electronic component, and the grounding and power wiring conductors 4b and 4c supply the ground potential and the power supply potential to the electronic component. In addition to functioning as a conductor, it also functions as a shield for electromagnetically shielding the signal wiring conductor 4a. Further, for example, by arranging the grounding first conductor layer 4b1 and the grounding second conductor layer 4b2 at a predetermined interval with respect to the signal wiring conductor 4a1, the signal wiring conductor 4a1 has a predetermined length. Characteristic impedance is given.

  Further, in the wiring board of this example, as shown in FIG. 2, the signal wiring conductor 4a1 formed in parallel has an end portion between the parallel portions and from the end portion to one side along the parallel portion. An end of the first grounding conductor layer 4b1 formed so as to extend is electrically connected to the second grounding conductor layer 4b2 by a through conductor 4bp penetrating the insulating layer 1b. As described above, the wiring board of the present invention has the end portion between the parallel portions of the parallel signal wiring conductors 4a1 and extends from the end portion to one side along the parallel portion. Since the end portion of one conductor layer 4b1 is electrically connected to the second conductor layer 4b2 for grounding by the through conductor 4bp penetrating the insulating layer 1b, it is between the parallel portions of the signal wiring conductor 4a1. The first conductor layer 4b1 for grounding formed so as to have one end along the parallel part from the end does not act as a stub or branch, and the signal wiring conductor 4a1 is 10 GHz. Even when a high-frequency signal exceeding 1 is propagated, resonance corresponding to the signal does not occur in the grounding first conductor layer 4b1, and as a result, the signal wiring conductor 4a has a high-frequency. The signal propagates well Te, it is possible to properly operate the electronic components mounted.

  If the distance from the edge of the first conductor layer 4b1 to the through conductor 4bp is equal to or greater than one-quarter of the wavelength of the signal propagating through the signal wiring conductor 4a1, resonance occurs in the first conductor layer 4b1. There is a risk of occurrence. Therefore, the distance from the edge of the first conductor layer 4b1 to the through conductor 4bp is preferably less than one quarter of the wavelength of the signal propagating through the signal wiring conductor 4a1.

  Further, when the first conductor layer 4b1 is formed so as to surround the parallel portion of the signal wiring conductor 2a1, the electromagnetic shielding of the signal wiring conductor 2a1 is enhanced, and a high-frequency signal is transmitted. It can be propagated more efficiently. Accordingly, the first conductor layer 4b1 is preferably formed so as to surround the periphery of the parallel portion of the signal wiring conductor 2a1.

  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.

  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 first conductor is used. Although the example in which the layer 4b1 and the second conductor layer 4b2 are ground conductor layers has been shown, these conductor layers may be power source conductor layers.

It is sectional drawing which shows the example of the best form for implementing the wiring board of this invention. (A) is a principal part top view of the example shown in FIG. 1, (b) is sectional drawing in the XX cutting | disconnection line of (a).

Explanation of symbols

1a, 1b: Insulating layer 4a1: Wiring conductor for signal 4b1: First conductor layer for ground or power supply 4b2: Second conductor layer for ground or power supply 4bp: Through conductor

Claims (3)

An insulating layer, a wiring conductor for signals plurality disposed on one main surface of the insulating layer, wherein the one main surface, two of said plurality of wiring conductors, the distance therebetween is one end An end portion is provided between parallel portions formed in parallel so as to expand toward the other end, and the end portion extends in a direction in which the interval extends along the parallel portion, and surrounds the periphery of the parallel portion. A first conductor layer for grounding or power supply formed as described above, and a second conductor for grounding or power supply facing at least the end portion on the other main surface of the insulating layer. A wiring board, wherein a layer is formed, and the second conductor layer and the end are electrically connected via a through conductor.   2. The wiring board according to claim 1, wherein a distance from an edge of the end portion to the through conductor is less than a quarter of a wavelength of a signal propagating through the signal wiring conductor. 3. An electronic device comprising: an electronic component mounted on the wiring board according to claim 1; and an electrode of the electronic component and the signal wiring conductor electrically connected.

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