JP2012190825A - Wiring board and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board from which static electricity is inexpensively discharged with a simple configuration and without increasing an area and thickness of the board, and by which the breakage and the malfunction due to static electricity of an electronic component are prevented.SOLUTION: This wiring board 10d includes a conductor protrusion part 871 which is electrically connected to a signal line region 81 and protrudes toward a ground region 72. The conductor protrusion part 871 is formed so as to intrude into an insulating layer 9, extends to a position close to the ground region 72 while keeping a state of being separated from the ground region 72, and forms a discharge gap between the ground region 72 and itself.

Description

  The present invention relates to a wiring board including an insulating layer and a conductor layer provided with the insulating layer interposed therebetween, and a method for manufacturing the wiring board.

  In a wiring board on which electronic components are mounted, measures against static electricity are taken in order to prevent malfunction due to static electricity and damage to electronic components. As an example of such a countermeasure against static electricity, a capacitor and a Zener diode are provided. Providing anti-static parts such as capacitors and Zener diodes in this way is effective as a countermeasure against static electricity, but increases the cost and limits the arrangement space for other circuit parts mounted on the wiring board. It becomes a factor.

  Therefore, a technique described in Patent Document 1 has been proposed as a countermeasure against static electricity without attaching an electrostatic countermeasure component. In the technique described in Patent Document 1 below, a plurality of peaks and valleys are formed by solder at the end of the pattern on the signal line side. Similarly, a plurality of crests and troughs are formed by solder at the end of the ground side pattern (see FIG. 1 of Patent Document 1 below). The peak portion at the pattern end portion on the signal line side and the peak portion at the pattern end portion on the ground side are provided so as to face each other, and a discharge gap is formed.

  In this way, the signal line and the ground electrode are arranged along the plane of the substrate and the discharge gap is formed by separating the signal line and the ground electrode from each other, because the discharge gap is formed by using the substrate in a plane. This reduces the planar utilization efficiency of the substrate. Therefore, a technique described in Patent Document 2 below has been proposed. Patent Document 2 below discloses a circuit board made of an insulating material, a conductive pattern formed on the surface of the circuit board, a conductive pattern formed on the back surface of the circuit board, and a conductive pattern on the surface and the back surface. A technique for forming a discharge gap by forming a conductive gap with a predetermined gap in the thickness direction of a circuit board is disclosed. More specifically, the inner peripheral surface of the through hole provided at the position where the conductive pattern is formed on the front surface and the back surface of the circuit board constitutes the discharge gap.

JP-A-5-67851 Japanese Patent Laid-Open No. 7-312471

  The techniques described in Patent Document 1 and Patent Document 2 do not use a capacitor or a Zener diode, and certainly reduce the number of components and contribute to cost reduction. However, as described above, since the technique described in Patent Document 1 uses a substrate in a planar manner to form a discharge gap, it reduces the planar utilization efficiency of the substrate.

  On the other hand, since the technique described in Patent Document 2 is configured such that the inner peripheral surface of the through hole penetrating the substrate becomes a discharge gap, the external connection terminal and the pad of the mounted component are stacked on the through hole. Can not be placed. For this reason, wiring to be drawn out from the external connection terminals and the pads of the mounted components, and a substrate area for providing a through hole are required, which hinders downsizing. Further, the distance of the discharge gap is limited by the interlayer thickness of the substrate.

  The present invention has been made in view of such problems, and the object thereof is to discharge electrostatic charges with a simple configuration at low cost without increasing the area and thickness of the substrate, and to destroy electronic components due to static electricity. It is an object of the present invention to provide a wiring board and a manufacturing method thereof that prevent malfunction.

  In order to solve the above problems, a wiring board according to the present invention is a wiring board including an insulating layer, and a first conductor layer and a second conductor layer provided with the insulating layer interposed therebetween. Is formed on the second conductor layer at a position facing the first wiring area and electrically connected to the first wiring area, while the second wiring area is formed. A conductor projection that protrudes toward the surface, the conductor projection is formed so as to enter the insulating layer, and extends to a position adjacent to the second wiring region while being separated from the second wiring region. A discharge gap is formed between the wiring region.

  According to the present invention, the conductor projection is formed in the first wiring region formed in the first conductor layer and protrudes toward the second wiring region, so that the first wiring region and the second wiring region are A discharge gap can be formed in the overlapping portion, and the planar utilization efficiency of the substrate is not reduced. Moreover, since the conductor convex portion is formed so as to enter the insulating layer, a discharge gap can be formed between the layers of the substrate. The conductor protrusion extends from the electrically connected first wiring region to a position close to the second wiring region while maintaining a state separated from the other non-electrically connected second wiring region. A discharge gap is formed between the second wiring region. By forming the discharge gap in this way, a discharge gap can be formed between the layers of the substrate. In addition, the discharge threshold value of the discharge gap can be adjusted by adjusting the distance between the conductor protrusion and the second wiring region. Therefore, it is possible to form a discharge gap in which the discharge threshold can be adjusted without changing the thickness of the substrate.

  In the wiring board according to the present invention, the conductor protrusion is formed so that the area of the portion surrounded by the outer periphery intersecting with the plane orthogonal to the direction extending from the first wiring region decreases toward the discharge gap. It is also preferable.

  In this preferred embodiment, since the area of the portion surrounded by the outer periphery of the conductor convex portion is configured to decrease toward the discharge gap side, the input to the first wiring region where the conductor convex portion is electrically connected. The static electricity that is generated can be reliably induced to the conductor protrusions and discharged reliably in the discharge gap.

  In the wiring board according to the present invention, it is also preferable that the conductor convex portion is formed so as to have a shape with a sharp tip on the discharge gap side.

  In this preferable aspect, the electric field can be concentrated on the tip by making the tip on the discharge gap side of the conductor convex portion sharp, and the discharge can be reliably discharged in the discharge gap.

  In the wiring board according to the present invention, it is also preferable that a pad for external connection or component connection is formed on the surface opposite to the portion where the conductor projection is formed in the first wiring region.

  In this preferable aspect, since the pad for external connection or component connection is formed on the opposite side of the portion where the conductor convex portion is formed, the discharge gap and the pad region for external connection or component connection are formed. It is possible to form at overlapping positions, and efficient arrangement within the substrate is possible. In addition, if a pad for external connection is formed on the surface opposite to the part where the conductor protrusions are formed, static electricity entering from the outside will be discharged without reaching the electronic components, causing malfunction or damage. The effect of preventing can be expected more.

  Further, in the wiring board according to the present invention, the conductor convex portion is electrically connected to the first wiring region and is electrically connected to the second wiring region and the first conductor convex portion protruding toward the second wiring region. A second conductor convex portion protruding toward the first wiring region, and the first conductor convex portion and the second conductor convex portion are formed so as to enter the insulating layer in a state of facing each other, and the other conductor It is also preferable to extend to a position close to the other conductor convex portion while maintaining a state separated from the convex portion, and to form a discharge gap between the other conductor convex portion.

  In this preferred embodiment, the first conductor convex portion extending from the first wiring region electrically connected to the second wiring region, and the second conductor convex portion extending from the second wiring region electrically connected to the first wiring region. The discharge gap is formed by configuring the first conductor convex portion and the second conductor convex portion extending from both regions to face each other while maintaining a state of being separated from each other. Therefore, the electric field can be concentrated at both ends facing each other, and the discharge can be reliably performed in the discharge gap.

  In the wiring board according to the present invention, the first conductor convex portion is formed such that the area of the portion surrounded by the outer periphery intersecting with the plane orthogonal to the direction extending from the first wiring region decreases toward the discharge gap side. The second conductor convex portion is preferably formed such that the area of the portion surrounded by the outer periphery intersecting with the plane orthogonal to the direction extending from the second wiring region decreases toward the discharge gap.

  In this preferable aspect, since the area of the part surrounded by the outer periphery of the first conductor convex part and the second conductor convex part is configured to decrease toward the discharge gap side, the first conductor convex part and the second conductor convex part Static electricity input to the region where the conductor convex portions are electrically connected can be reliably induced, and can be reliably discharged in the discharge gap.

  In the wiring board according to the present invention, it is also preferable that the first conductor convex portion and the second conductor convex portion are formed so as to have a sharpened tip on the discharge gap side.

  In this preferred embodiment, by forming the tips on the discharge gap side of the first conductor convex portion and the second conductor convex portion so as to have a sharp shape, the electric field can be concentrated on the tip, and the discharge can be reliably discharged in the discharge gap.

  In the wiring board according to the present invention, it is also preferable that the conductor protrusion is filled with a conductive material.

  In this preferred embodiment, the conductor protrusion is formed by filling the inside with a conductive material, so that the impedance can be kept low and the discharge of static electricity is facilitated.

  In order to solve the above problems, a method for manufacturing a wiring board according to the present invention is a method for manufacturing a wiring board comprising an insulating layer, and a first conductor layer and a second conductor layer provided with the insulating layer interposed therebetween. A first step of forming an insulating layer and a first conductor layer and a second conductor layer provided across the insulating layer; entering the insulating layer from the first conductor layer side; the first conductor layer and the second conductor A second step of forming via conductors connecting the layers. In the second step, a conductor projection that is electrically connected to the first wiring region of the first conductor layer and protrudes toward the second wiring region of the second conductor layer enters the insulating layer, and Is formed so as to extend to a position close to the second wiring region while maintaining a separated state, and a discharge gap is formed with the second wiring region.

  According to the present invention, in the second step of forming the via conductor that connects the first conductor layer and the second conductor layer, the conductor protrusion for forming the discharge gap can be formed. Therefore, the discharge gap is formed inside the wiring board by a simple method of forming a conductor convex portion that does not contact the second wiring region of the second conductor layer without adding a separate step for forming the discharge gap. be able to.

  According to the present invention, there is provided a wiring board that discharges static electricity at a low cost with a simple configuration without increasing the area and thickness of the board, and prevents damage and malfunction of electronic components due to static electricity, and a method for manufacturing the same. Can do.

It is typical sectional drawing for demonstrating the discharge gap in the wiring board which concerns on embodiment of this invention. It is typical sectional drawing for demonstrating the shape of the conductor convex part in FIG. It is typical sectional drawing for demonstrating the wiring board as a modification. It is typical sectional drawing for demonstrating the wiring board as a modification. It is typical sectional drawing for demonstrating the wiring board as a modification. It is typical sectional drawing for demonstrating the whole wiring board comprised using the conductor convex part of the form shown in FIG. It is typical sectional drawing which shows the modification of the wiring board shown in FIG. It is typical sectional drawing for demonstrating the outline | summary of the manufacturing process of the wiring board which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  A wiring board according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view for explaining a discharge gap in a wiring board 10 according to an embodiment of the present invention. As shown in FIG. 1, the wiring board 10 includes an insulating layer 4, and a first conductor layer 2 and a second conductor layer 3 provided with the insulating layer 4 interposed therebetween.

  The first conductor layer 2 is formed with a signal line region 20 for transmitting and receiving signals. Although only the signal line region 20 is shown in FIG. 1, other signal line regions and ground regions may be formed in the first conductor layer 2.

  In the second conductor layer 3, a ground region 30 connected to the ground potential is formed. Although only the ground region 30 is illustrated in FIG. 1, other signal line regions and ground regions may be formed in the second conductor layer 3. The ground region 30 is formed at a position facing the signal line region 20.

  A conductor protrusion 24 is formed in the signal line region 20. The conductor convex part 24 is a cup-shaped thing integrally formed with the signal line region 20 so as to be electrically connected to the signal line region 20. The conductor protrusion 24 is formed so as to protrude toward the ground region 30 from the surface of the signal line region 20 on the insulating layer 4 side.

  The conductor convex part 24 is constituted by an inclined wall part 25 and a bottom part 26. The bottom portion 26 is formed to be smaller than a portion where the inclined wall portion 25 is connected to the signal line region 20. The inclined wall portion 25 is formed so as to connect the signal line region 20 and the bottom portion 26. Therefore, the outer shape of the conductor protrusion 24 has a truncated cone shape.

  The conductor protrusion 24 is formed so as to enter the insulating layer 4 and extends to a position close to the ground region 30 while maintaining a state separated from the ground region 30 which is the other region. The discharge gap g is formed. By forming the discharge gap g in this manner, even if static electricity is input to the signal line region 20 side, it is possible to discharge through the discharge gap g.

  In the conductor protrusion 24, the area of the portion surrounded by the outer periphery intersecting with the plane orthogonal to the direction extending from the signal line region 20 (the direction from the signal line region 20 to the ground region 30) decreases toward the discharge gap g. It is formed as follows.

  The shape of such a conductor convex part 24 is demonstrated referring FIG. 2A and 2B are schematic cross-sectional views for explaining the shape of the conductor protrusion 24 in FIG. 1, wherein FIG. 2A shows a cross-section at the cutting plane PLa in FIG. 1, and FIG. The cross section in plane PLb is shown, (C) has shown the cross section in the cutting plane PLc of FIG. The cutting planes PLa, PLb, and PLc are arranged such that the cutting plane PLa is disposed closest to the signal line region 20, the cutting plane PLc is arranged so as to pass through the bottom 26, and the cutting plane PLb is between the cutting planes PLa and PLc. Is arranged.

  As shown in FIG. 2A, the inclined wall portion 25 of the conductor convex portion 24 that intersects the cutting plane PLa has an annular cross section by an outer periphery 251a and an inner periphery 252a. As shown in FIG. 2B, the inclined wall portion 25 of the conductor convex portion 24 intersecting with the cutting plane PLb has an annular cross section by an outer periphery 251b and an inner periphery 252b. As shown in FIG. 2C, the bottom portion 26 of the conductor convex portion 24 that intersects the cutting plane PLc has a circular cross section surrounded by the outer periphery 261.

  Since the planes orthogonal to the direction extending from the signal line region 20 (the direction from the signal line region 20 to the ground region 30) are the cut planes PLa, PLb, and PLc, the portion surrounded by the outer periphery that intersects these planes is the outer periphery 251a. The inner part surrounded by the outer periphery 251b, the inner part surrounded by the outer periphery 251b, and the inner part surrounded by the outer periphery 261. Accordingly, the area of each part is the largest in the area surrounded by the outer periphery 251a which is the largest circle, the area of the part surrounded by the outer periphery 251b which is the next largest circle is wide, and the outer periphery 261 which is the smallest circle. The area of the enclosed part (the area of the bottom part 26) is the smallest.

  As shown in FIGS. 1 and 2, the conductor convex portion 24 is formed in a truncated cone shape and is formed so as to be narrowed toward the ground region 30, thereby ensuring the discharge effect in the discharge gap g. In addition, the aspect in which the conductor convex part 24 is narrowed as it goes to the ground region 30 is not limited to that narrowed to a uniform frustoconical shape. A mode of combining them can also be adopted.

  In the present embodiment, the signal line region 20 is formed as one corresponding to the first wiring region of the present invention, and the ground region 30 is formed as one corresponding to the second wiring region of the present invention. However, the first wiring region and the second wiring region are not limited to these, and can be arbitrarily formed at a place where it is necessary to cause a function of discharging static electricity from one to the other. Therefore, for example, it is also preferable to form a signal line region for transmitting and receiving signals as the first wiring region, while forming a discharge target region to be discharged as the second wiring region. As the discharge target region, a part of the power supply line may be used, or a special region for discharge may be formed.

  A modification of the wiring board 10 described with reference to FIGS. 1 and 2 is shown in FIG. FIG. 3 is a schematic cross-sectional view showing a wiring board 10a as a modification. The wiring board 10a shown in FIG. 3 is obtained by changing the conductor protrusion 24 of the wiring board 10 to the conductor protrusion 24a and providing a resist layer 351a and a pad 352a. The pad 352a corresponds to a region in the signal line region 20 that is not covered with the resist layer 351a. The conductor convex portion 24a is a convex portion formed integrally with the signal line region 20 so as to be electrically connected to the signal line region 20, and the conductor convex portion 24a is formed inside the conductor convex portion 24 shown in FIG. It is filled with a conductor.

  Thus, by filling the inside of the cup-shaped conductor convex part 24 with a conductor to form the conductor convex part 24a, the impedance can be suppressed low, and the discharge effect in the discharge gap g can be further enhanced.

  Further, in the wiring substrate 10a, a pad 352a as a terminal region for external connection is formed on the surface (upper surface in the drawing) opposite to the portion where the conductor protrusion 24a is formed in the signal line region 20. A resist layer 351a is formed in the signal line region 20 on both outer sides of the pad 352a. Thus, according to the wiring board 10a, since the pad 352a can be provided at a position overlapping the conductor protrusion 24a that forms the discharge gap g, the wiring board 10a can be further reduced in size.

  FIG. 4 shows a wiring board 10b which is a further modification of the wiring board 10a shown in FIG. FIG. 3 is a schematic cross-sectional view showing a wiring board 10b as a modification. The wiring board 10b shown in FIG. 4 has a conical shape with a pointed tip on the ground region 30 side of the conductor protrusion 24a filled with a conductor.

  In this way, by filling the inside of the cup-shaped conductor convex portion 24 with a conductor and sharpening the tip portion on the ground region 30 side, the electric field tends to concentrate on the tip portion and discharge is likely to occur. Can be configured.

  The conductor convex portion may be cylindrical or prismatic, but considering the discharge effect in the discharge gap g, it is also preferably a truncated cone shape, a truncated pyramid shape or a hemispherical shape, and as described above, A conical shape or a pyramid shape is more preferable.

  Further, a modified example for further enhancing the electric field concentration effect at the tip of the conductor convex portion will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view for explaining a wiring board 10c as a modified example.

  As shown in FIG. 5, the wiring substrate 10 c includes an insulating layer 4, and a first conductor layer 2 and a second conductor layer 3 provided with the insulating layer 4 interposed therebetween.

  The first conductor layer 2 is formed with a signal line region 20 for transmitting and receiving signals. In the second conductor layer 3, a ground region 30 connected to the ground potential is formed. The ground region 30 is formed at a position facing the signal line region 20.

  In the signal line region 20, a first conductor convex portion 24c is formed. The first conductor convex portion 24 c has a cup-like shape formed integrally with the signal line region 20 so as to be electrically connected to the signal line region 20. The first conductor protrusion 24 c is formed so as to protrude toward the ground region 30 from the surface of the signal line region 20 on the insulating layer 4 side.

  The first conductor convex portion 24c is composed of an inclined wall portion 25c and a bottom portion 26c. The bottom portion 26 c is formed to be smaller than the portion where the inclined wall portion 25 c is connected to the signal line region 20. The inclined wall portion 25c is formed so as to connect the signal line region 20 and the bottom portion 26c. Accordingly, the outer shape of the first conductor convex portion 24c has a truncated cone shape.

  In the ground region 30, a second conductor convex portion 29c is formed. The second conductor convex portion 29 c is a cup-shaped member formed integrally with the signal line region 20 so as to be electrically connected to the signal line region 20. The second conductor protruding portion 29 c is formed so as to protrude toward the signal line region 20 from the surface of the ground region 30 on the insulating layer 4 side.

  The 2nd conductor convex part 29c is comprised by the inclined wall part 27c and the bottom part 28c. The bottom portion 28 c is formed to be smaller than a portion where the inclined wall portion 27 c is connected to the ground region 30. The inclined wall portion 27c is formed so as to connect the ground region 30 and the bottom portion 28c. Therefore, the outer shape of the second conductor convex portion 29c has a truncated cone shape.

  The first conductor convex portion 24c and the second conductor convex portion 29c are formed so as to enter the insulating layer 4, and extend to a position close to the other conductor convex portion while maintaining a state separated from the other conductor convex portion, A discharge gap gc is formed by forming a gap with the other conductor convex portion. By forming the discharge gap gc in this way, even if static electricity is input to the signal line region 20 side, it is possible to discharge through the discharge gap gc.

  The area of the first conductor convex portion 24c surrounded by the outer periphery intersecting with the plane orthogonal to the direction extending from the signal line region 20 (the direction from the signal line region 20 to the ground region 30) is toward the discharge gap gc side. It is formed to decrease. Further, the second conductor convex portion 29c has an area of a portion surrounded by an outer periphery intersecting with a plane orthogonal to a direction extending from the ground region 30 (a direction from the ground region 30 toward the signal line region 20) toward the discharge gap gc. It is formed to decrease.

  As described above, when the first conductor convex portion 24c and the second conductor convex portion 29c are provided so as to approach each other from the opposing signal line region 20 and the ground region 30, the gap is formed in such a shape that the tips of each other face each other. The electric field is concentrated by the tip portions of each other, and the discharge effect of the discharge gap gc can be further enhanced. Of course, the shapes of the first conductor convex portion 24c and the second conductor convex portion 29c are preferably the shapes shown in FIGS. 3 and 4 or the shapes described with reference to FIGS. .

  Next, how the above-described conductor protrusions 24, 24a, 24b, 24c, and 29c are arranged in the entire substrate will be described with reference to FIG. FIG. 6 is a schematic cross-sectional view for explaining the entire substrate assembly AP configured using the same conductor protrusions as the conductor protrusions 24a in the form shown in FIG.

  As shown in FIG. 6, the board assembly AP is obtained by mounting an IC chip CP on a wiring board 10d. The IC chip CP is mounted on the conductor layer 5 side of the wiring board 10d. Specifically, the IC chip CP has an IC terminal Ts on the signal line side and an IC terminal Tg on the ground side. The IC terminal Ts on the signal line side is connected to the signal line region 51 of the conductor layer 5. The IC terminal Tg on the ground side is connected to the ground region 52 of the conductor layer 5.

  The wiring board 10 d is a four-layer multilayer board having the conductor layer 5, the conductor layer 6, the conductor layer 7, and the conductor layer 8. An insulating layer 9 is formed between each of the conductor layer 5, the conductor layer 6, the conductor layer 7, and the conductor layer 8. Actually, since the insulating layer 9 is formed while being laminated, the inside thereof is formed in layers.

  The uppermost conductor layer 5 has a signal line region 51 and a ground region 52. The conductor layer 6 has a signal line region 61 and a ground region 62. The conductor layer 7 has a signal line region 71 and a ground region 72. The lowermost conductor layer 8 has a signal line region 81 and a ground region 82.

  The signal line region 51 and the signal line region 61 are connected by a via conductor 561. The signal line region 61 and the signal line region 71 are connected by a via conductor 671. The signal line region 71 and the signal line region 81 are connected by a via conductor 781. Therefore, the signal line region 51, which is an external connection terminal, and the IC chip CP are formed by the signal line region 51, the via conductor 561, the signal line region 61, the via conductor 671, the signal line region 71, the via conductor 781, and the signal line region 81. A connecting signal line is formed.

  The ground region 52 and the ground region 62 are connected by a via conductor 562. The ground region 62 and the ground region 72 are connected by a via conductor 672. The ground region 72 and the ground region 82 are connected by a via conductor 782. Therefore, the ground region 52, the via conductor 562, the ground region 62, the via conductor 672, the ground region 72, the via conductor 782, and the ground region 82 form a ground line that connects the ground region 82 that is the external connection terminal and the IC chip CP. Has been.

  In the case of the substrate assembly AP shown in FIG. 6, a conductor projection 871 is formed between the signal line region 81 that is an external connection terminal and the ground region 72. The conductor convex portion 871 is electrically connected to the signal line region 81, is formed so as to enter the insulating layer 9, and is close to the ground region 72 while maintaining a state separated from the ground region 72 which is the other region. A discharge gap is formed with the ground region 72. Since static electricity often enters from the outside, forming the conductive protrusion 871 in the signal line region 81 that is the external connection terminal to form the discharge gap in this way ensures that the static electricity enters the IC chip CP. This is extremely effective as a countermeasure against static electricity.

  Next, a modified example of the substrate assembly AP will be described with reference to FIG. FIG. 7 is a schematic cross-sectional view for explaining an entire substrate assembly APa that is configured as a modified example of the substrate assembly AP using conductor protrusions similar to the conductor protrusions 24a of the form shown in FIG.

  As shown in FIG. 7, the substrate assembly APa is obtained by mounting an IC chip CP on a wiring substrate 10e. The IC chip CP is mounted on the conductor layer 5a side of the wiring board 10e. Specifically, the IC chip CP has an IC terminal Ts on the signal line side and an IC terminal Tg on the ground side. The IC terminal Ts on the signal line side is connected to the signal line region 51 a of the conductor layer 5. Further, the IC terminal Tg on the ground side is connected to the ground region 52a of the conductor layer 5a.

  The wiring board 10e is a four-layer multilayer board having a conductor layer 5a, a conductor layer 6a, a conductor layer 7a, and a conductor layer 8a. An insulating layer 9a is formed between each of the conductor layer 5a, the conductor layer 6a, the conductor layer 7a, and the conductor layer 8a. Actually, since the insulating layer 9a is formed while being laminated, the inside thereof is formed in layers.

  The uppermost conductor layer 5a has a signal line region 51a and a ground region 52a. The conductor layer 6a has a signal line region 61a and a ground region 62a. The conductor layer 7a has a signal line region 71a and a ground region 72a. The lowermost conductor layer 8a has a signal line region 81a and a ground region 82a.

  The signal line region 51a and the signal line region 61a are connected by a via conductor 561a. The signal line region 61a and the signal line region 71a are connected by a via conductor 671a. The signal line region 71a and the signal line region 81a are connected by a via conductor 781a. Therefore, the signal line region 81a which is an external connection terminal and the IC chip CP are formed by the signal line region 51a, the via conductor 561a, the signal line region 61a, the via conductor 671a, the signal line region 71a, the via conductor 781a, and the signal line region 81a. A connecting signal line is formed.

  The ground region 52a and the ground region 62a are connected by a via conductor 562a. The ground region 62a and the ground region 72a are connected by via conductors 672a and 673a. The ground region 72a and the ground region 82a are connected by a via conductor 782a. Accordingly, the ground line connecting the ground region 82a which is an external connection terminal and the IC chip CP by the ground region 52a, the via conductor 562a, the ground region 62a, the via conductors 672a and 673a, the ground region 72a, the via conductor 782a, and the ground region 82a. Is formed.

  In the case of the substrate assembly APa shown in FIG. 7, a conductor protrusion 651 is formed between the signal line region 51a directly connected to the IC terminal Ts on the signal line side of the IC chip CP and the ground region 62a. The conductor protrusion 651 is formed immediately below the IC terminal Ts on the signal line side of the IC chip CP. The conductor protrusion 651 is electrically connected to the signal line region 51a, is formed so as to enter the insulating layer 9a, and close to the ground region 62a while maintaining a state separated from the ground region 62a which is the other region. A discharge gap is formed with the ground region 62a. Thus, by forming the conductor convex portion 651 directly under the IC terminal Ts on the signal line side of the IC chip CP, the substrate assembly APa can be reduced in size.

  Next, a method for manufacturing a wiring board according to the present embodiment will be described with reference to FIG. FIG. 8 is a diagram showing steps for forming a conductor protrusion 161 similar to the conductor protrusion 24 as a form in order to briefly explain the method of manufacturing a wiring board.

  As shown in FIG. 8A, the copper foil 22 and the copper foil 32 are attached to both surfaces of the insulating layer 42. Subsequently, as shown in FIG. 8B, a hole is formed with a laser from the copper foil 22 side to form a recess 16 and a recess 17. Since the concave portion 16 becomes the conductor convex portion 24, the concave portion has a depth that does not reach the copper foil 32. Since the recess 17 serves as a via conductor, the recess 17 has a depth enough to reach the copper foil 32.

  Subsequently, as shown in FIG. 8C, copper plating is applied to the entire surface. By this copper plating, a copper plating layer 33 is formed outside the copper foil 32. Further, a copper plating layer 23 is formed so as to cover the outside of the copper foil 22 and the inside of the recesses 16 and 17. Accordingly, the copper foil 22 and the copper plating layer 23 are integrated to form a conductor layer, and the copper foil 32 and the copper plating layer 33 are integrated to form a conductor layer.

  Subsequently, as shown in FIG. 8D, a wiring pattern is formed by photolithography. Through the above-described steps, the conductor convex portion 161 having the inclined wall portion 161a and the bottom portion 161b is formed. A via conductor 151 having an inclined wall portion 151a and a bottom portion 151b is formed.

  The distance between the bottom 161b and the copper foil 32 (conductor layer) is set to a distance that does not discharge at a voltage normally used in a circuit but discharges only when a high voltage such as static electricity or surge is applied. In the present embodiment, as shown in FIGS. 8B to 8D, since the conductor convex portion 161 is formed by making a hole with a laser, the depth of the hole formed by the laser is adjusted. Thus, it is possible to form a discharge gap that discharges at a voltage suitable for the circuit.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

DESCRIPTION OF SYMBOLS 10: Wiring board 2: 1st conductor layer 3: 2nd conductor layer 4: Insulating layer 20: Signal line area | region 24: Conductor convex part 25: Inclined wall part 251a, 251b: Outer periphery 252a, 252b: Inner periphery 26: Bottom 261 : Outer periphery 30: ground region g: discharge gap PLa, PLb, PLc: cutting plane

Claims (9)

A wiring board comprising an insulating layer, and a first conductor layer and a second conductor layer provided across the insulating layer,
A first wiring region is formed in the first conductor layer, while a second wiring region is formed in the second conductor layer at a position facing the first wiring region,
A conductor projection electrically connected to the first wiring region and projecting toward the second wiring region;
The conductor convex portion is formed so as to enter the insulating layer, extends to a position close to the second wiring region while maintaining a state separated from the second wiring region, and between the second wiring region A wiring board characterized by forming a discharge gap.   The conductor convex portion is formed so that an area of a portion surrounded by an outer periphery intersecting with a plane orthogonal to a direction extending from the first wiring region decreases toward the discharge gap side. Item 4. The wiring board according to Item 1.   The wiring board according to claim 2, wherein the conductor protrusion is formed so as to have a pointed tip on the discharge gap side.   2. The wiring board according to claim 1, wherein a pad for external connection or component connection is formed on a surface of the first wiring region opposite to a portion where the conductor protrusion is formed. . The conductor convex portion is electrically connected to the first wiring region and is electrically connected to the second wiring region, and a first conductor convex portion that is electrically connected to the first wiring region and protrudes toward the second wiring region. A second conductor convex portion projecting toward the
The first conductor convex portion and the second conductor convex portion are formed so as to enter the insulating layer in a state of being opposed to each other, and are separated from the other conductor convex portion while being separated from the other conductor convex portion. The wiring board according to claim 1, wherein the wiring board extends to an adjacent position and forms a discharge gap with the other conductor convex portion. The first conductor convex portion is formed so that an area of a portion surrounded by an outer periphery intersecting with a plane orthogonal to a direction extending from the first wiring region decreases toward the discharge gap side,
The second conductor convex portion is formed such that an area of a portion surrounded by an outer periphery intersecting with a plane orthogonal to a direction extending from the second wiring region decreases toward the discharge gap side. The wiring board according to claim 5.   The wiring board according to claim 6, wherein the first conductor convex portion and the second conductor convex portion are formed so as to have a sharpened tip on the discharge gap side.   The wiring board according to claim 1, wherein the conductor protrusion is filled with a conductive material. A method for manufacturing a wiring board comprising an insulating layer, and a first conductor layer and a second conductor layer provided across the insulating layer,
A first step of forming an insulating layer, and a first conductor layer and a second conductor layer provided across the insulating layer;
A second step of forming a via conductor that enters the insulating layer from the first conductor layer side and connects the first conductor layer and the second conductor layer, and
In the second step, a conductor protrusion that is electrically connected to the first wiring region of the first conductor layer and protrudes toward the second wiring region of the second conductor layer enters the insulating layer, and The wiring board is formed so as to extend to a position close to the second wiring area while maintaining a state separated from the second wiring area, and a discharge gap is formed between the second wiring area and the second wiring area. Production method.

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