WO2012176453A1

WO2012176453A1 - Wiring board

Info

Publication number: WO2012176453A1
Application number: PCT/JP2012/004028
Authority: WO
Inventors: 康裕貝崎; 中里　真弓
Original assignee: 三洋電機株式会社
Priority date: 2011-06-23
Filing date: 2012-06-21
Publication date: 2012-12-27
Also published as: JP2014160690A

Abstract

A first wiring layer includes a differential transmission line pair (12). A second wiring layer (8) includes a conductor region (18). A second insulating layer is provided between the wiring layer and the second wiring layer (8). The second wiring layer (8) contains, in a conductor region (18), a non-conductive region (20) having plane symmetry with respect to the plane of symmetry (50) of the differential transmission line pair in the wiring layer. Here, a plurality of non-conductive regions (20) are positioned on the second wiring layer (8), and these regions are formed contiguously on the plane of symmetry (50) of the differential transmission line pair (12).

Description

Wiring board

The present invention relates to a wiring board including a differential transmission line.

Conventionally, so-called common mode chokes have been used to reduce common mode current and noise emission. For example, the common mode choke has a structure in which a normal phase signal line and a negative phase signal line are wound around a donut-shaped ferrite core. When winding the common mode choke, the differential mode current is in the direction of canceling the magnetic flux, so the impedance of the common mode choke is low and the magnetic flux is strengthened against the common mode current. Therefore, the impedance of the common mode choke is high. Therefore, only common mode signals can be attenuated efficiently. It is also considered that a common mode choke is formed by a multilayer structure for miniaturization (see

Patent Documents

1, 2, and 3).

JP 2004-311829 A Japanese Patent No. 3545245 Japanese Patent No. 3863674 JP 2011-55122 A JP-A-6-85412 JP 2000-91807 A JP 2008-64780 A JP 2004-253746 A

However, in a signal including high-order harmonics of the fundamental frequency such as a digital signal, the waveform in the differential mode may be destroyed due to attenuation of the high-frequency component.

The present invention has been made in view of these problems, and an object thereof is to provide a technique for reducing the influence of common mode in a wiring board having a differential transmission line pair.

In order to solve the above problems, a wiring board according to an aspect of the present invention includes a first wiring layer including a differential transmission line pair, a second wiring layer including a conductor region, a first wiring layer, and a second wiring layer. And an insulating layer provided between the two. The second wiring layer includes a non-conductor region having a plane-symmetric shape in the conductor region with respect to the symmetry plane of the differential transmission line pair in the first wiring layer.

According to the present invention, the influence of the common mode can be reduced in the wiring board having the differential transmission line pair.

It is a perspective view which shows typically the structure of the wiring board which concerns on Example 1 of this invention, and the module attached to it. It is a top view which shows the structure of the filter area | region of FIG. It is sectional drawing which shows the structure of the filter area | region of FIG. FIGS. 4A to 4D are diagrams for explaining the impedance in the differential mode and the common mode by the differential transmission line pair in FIG. It is a graph which shows the simulation result of the passage characteristic of the differential transmission line pair of FIG. It is a top view of the filter area | region which concerns on Example 2 of this invention. It is a top view of the filter area | region which concerns on Example 3 of this invention. It is a top view of the filter area | region which concerns on Example 4 of this invention. It is a top view of the filter area | region which concerns on Example 5 of this invention. It is a top view of the filter area | region which concerns on Example 6 of this invention. It is a top view of the filter area | region which concerns on Example 7 of this invention. It is a perspective view which shows the structure of the mobile telephone based on Example 8 of this invention. It is a fragmentary sectional view of the mobile phone of FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to specific description of embodiments of the present invention, the knowledge that is the basis will be described. The differential transmission method is a transmission method that is not easily affected by electromagnetic noise, and is widely used in general. The differential transmission method is a method of generating a two-phase signal of a normal phase signal and a reverse phase signal from one signal and transmitting it using two signal lines. In this method, since the phases of the normal phase signal and the negative phase signal are reversed (shifted by 180 degrees) in an ideal state, the magnetic fluxes generated are mutually canceled. As a result, the influence of the inductor component of the line is reduced. Hereinafter, a mode in which a signal is transmitted in this ideal state (a state in which the phase of the normal phase signal and the reverse phase signal is inverted) in the differential transmission method is referred to as a differential mode.

However, in an actual circuit, it is difficult to completely equalize the length of the normal phase signal line through which the normal phase signal flows and the length of the negative phase signal line through which the negative phase signal flows. In many cases, the equilibrium between the two is broken. When the balance is lost, a signal having the same phase flows through the positive-phase signal line and the negative-phase signal line. Hereinafter, a mode in which a signal having the same phase is transmitted to two signal lines in the differential transmission method is referred to as a common mode. That is, in an actual circuit, a pair of differential transmission lines often transmits two types of signals, that is, a differential mode signal and a common mode signal. Hereinafter, in this specification, a pair of differential transmission lines is described as a differential transmission line pair.

The common mode current generated in the differential transmission line is different from the differential transmission line, and forms a loop mainly through the ground conductor path. When the common mode current flows through this loop, electromagnetic noise is radiated, and electromagnetic noise entering from the outside enters this loop, so that electromagnetic noise is superimposed on the differential transmission line. The amount of noise radiation is proportional to the magnitude of the common mode current and the loop area. As described above, so-called common mode chokes have been used in the past to reduce common mode current and reduce noise emission.

However, in recent years, the frequency of signals used in electronic devices has been increasing, and there are cases where a common mode choke having a ferrite core cannot be used. This is because, in ferrite, it is difficult to maintain the magnetic permeability at a high frequency, and in the high frequency region, the loss in the differential mode signal in the common mode choke increases. In particular, in a signal including high-order harmonics of the fundamental frequency, such as a digital signal, the waveform in the differential mode may be destroyed due to attenuation of high-frequency components.

Example 1
Before describing the present invention in detail, an outline will be described. Example 1 of this invention is related with the wiring board mounted in portable apparatuses, such as a mobile telephone. The wiring board according to the present embodiment includes, for example, a differential transmission line pair that transmits a high frequency signal of 1 GHz or more. The wiring board forms a common mode filter region so as to include a path in the middle of the differential transmission line pair in order to reduce the influence of the common mode on the differential transmission line pair. The common mode filter region filters the common mode signal while suppressing the attenuation of the differential mode signal. Here, in the common mode filter region, the common mode impedance is increased by resonating the differential transmission line pair and the ground pattern at a specific frequency.

The ground pattern is formed in a second wiring layer different from the first wiring layer in which the differential transmission line pair is disposed. More specifically, the second wiring layer includes a conductor region and a non-conductor region. Of these, the non-conductor region resonates with the differential transmission line pair. In order to effectively resonate, the non-conductive region has a plane-symmetric shape with respect to the plane of symmetry of the differential transmission line pair. Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. The same or equivalent components and members shown in the drawings are denoted by the same reference numerals, and repeated descriptions are appropriately omitted. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding.

FIG. 1 is a perspective view schematically showing a configuration of a wiring board 100 and a module attached thereto according to Embodiment 1 of the present invention. A first semiconductor module 102 and a second semiconductor module 104 are attached to the upper surface 100 a of the wiring board 100. Hereinafter, the side on which the first semiconductor module 102 and the second semiconductor module 104 are attached in the wiring board 100 will be described as the upper side. The first semiconductor module 102 and the second semiconductor module 104 are, for example, modules in which a die on which an integrated circuit having a desired function is formed is packaged.

The wiring substrate 100 has a laminated structure in which the second wiring layer 8, the second insulating layer 6, the first wiring layer 4, and the first insulating layer 2 are laminated in this order from the lower side to the upper side. This stacking direction is defined as stacking direction A1. In FIG. 1, the stacking direction A <b> 1 is a direction perpendicular to the upper surface 100 a of the wiring substrate 100. The first wiring layer 4 includes a differential transmission line pair 12. The differential transmission line pair 12 transmits a high frequency signal of 1 GHz or more between the first semiconductor module 102 and the second semiconductor module 104. The differential transmission line pair 12 traverses the filter region 10 (region surrounded by a two-dot chain line in FIG. 1) of the wiring substrate 100. In the filter region 10, the common mode signal is filtered from the high frequency signal transmitted through the differential transmission line pair 12. The second wiring layer 8 is grounded.

The first insulating layer 2 and the second insulating layer 6 are formed of an insulating material such as epoxy resin or alumina. The differential transmission line pair 12 is made of metal such as aluminum, gold, copper, silver platinum (AgPt), silver palladium (AgPd). The thickness of the first insulating layer 2 is about 40 μm, the thickness of the first wiring layer 4 is about 18 μm, the thickness of the second insulating layer 6 is about 40 μm, and the thickness of the second wiring layer 8 is about 18 μm.

FIG. 2 is a top view showing the configuration of the filter region 10. This is a plan view seen from the upper surface 100 a of the filter region 10. In FIG. 2, the first insulating layer 2 and the second insulating layer 6 in FIG. 1 are omitted. The AA line in FIG. 2 corresponds to the AA line in FIG. On the other hand, FIG. 3 is a cross-sectional view taken along the line AA of FIG. In FIG. 3, parts other than the filter region 10 are omitted. As shown in FIG. 2, the second wiring layer 8 includes a conductor region 18 and a non-conductor region 20. The non-conductor region 20 includes a first non-conductor region 20a, a second non-conductor region 20b, a third non-conductor region 20c, a fourth non-conductor region 20d, a fifth non-conductor region 20e, a sixth non-conductor region 20f, and a seventh non-conductor region. The non-conductor region 20g, the eighth non-conductor region 20h, the ninth non-conductor region 20i, the tenth non-conductor region 20j, the eleventh non-conductor region 20k, and the twelfth non-conductor region 20l. The conductor region 18 is made of a metal such as aluminum, gold, copper, silver platinum (AgPt), or silver palladium (AgPd).

As shown in FIG. 2, in the first wiring layer 4, the transmission lines in the differential transmission line pair 12 are arranged in parallel at a predetermined interval. Further, the symmetry plane 50 of the differential transmission line pair 12 is defined so as to include the center line between the transmission lines. Here, the symmetry plane 50 is a vertical plane of the first wiring layer 4. The second wiring layer 8 includes a plurality of non-conductor regions 20 in the conductor region 18. The conductor region 18 is made of metal and is grounded. On the other hand, the non-conductor region 20 is filled with an insulator such as an epoxy resin, that is, a non-conductive material.

Each non-conductor region 20 (20a to 20l) in the second wiring layer 8 has a plane-symmetric shape with respect to the plane of symmetry 50 of the differential transmission line pair 12. Further, as shown in FIG. 2, each non-conductor region 20 (20a to 20l) has a straight slot shape, and is continuously formed in a strip shape so as to intersect the symmetry plane 50. Thus, each non-conductor region 20 is three-dimensionally crossed with the differential transmission line pair 12. Note that the length, width, and shape of each non-conductor region 20 are designed to be the same.

As shown in FIG. 3, the differential transmission line pair 12 is disposed in the first wiring layer 4, and the first wiring layer 4 is formed as a layer different from the second wiring layer 8. The first wiring layer 4 includes a differential transmission line pair 12 and an insulator 22 such as an epoxy resin. An insulator 22 such as epoxy resin fills the gap between the differential transmission line pair 12.

FIGS. 4A to 4D are diagrams for explaining the impedance in the differential mode and the common mode by the differential transmission line pair 12. 4A shows the differential mode, and FIG. 4B shows the common mode. Here, the differential transmission line pair 12 is formed of a first transmission line 12a and a second transmission line 12b. In general, when a transmission line is formed of N conductors, (N-1) independent TEM wave modes exist with one of them as a ground. Here, since the 1st transmission line 12a, the 2nd transmission line 12b, and the 2nd wiring layer 8 are arrange | positioned, two modes exist. In particular, when the first transmission line 12a and the second transmission line 12b are just at the same potential as the reverse potential, they are called a differential mode and a common mode, respectively.

The impedance is defined as follows from the voltage and current of each mode.
vdif = v1-v2 (v1 = -v2)
idif = i1 = −i2
Zdif = vdif / idif = (v1-v2) / ((i1-i2) / 2)
vcom = v1 = v2
icom = i1 + i2 (i1 = i2)
Zcom = vcom / icom = ((v1 + v2) / 2) / (i1 + i2)
Here, vdif, idif, and Zdif are a differential voltage, a differential current, and a differential impedance, and vcom, icom, and Zcom are a common voltage, a common current, and a common impedance.

Here, the differential impedance Zdif is a characteristic impedance between the first transmission line 12a and the second transmission line 12b, and the common impedance Zcom is a characteristic impedance between the differential transmission line pair 12 and the second wiring layer 8. Therefore, the images shown in FIGS. 4C and 4D are obtained. FIG. 4C corresponds to the differential mode, and FIG. 4D corresponds to the common mode. In the differential mode of the differential line, it is hardly affected by the adjacent second wiring layer 8, but in the common mode, it is strongly influenced by the second wiring layer 8.

FIG. 5 is a graph showing a simulation result of the pass characteristics of the differential transmission line pair 12. The horizontal axis indicates the frequency (GHz) of the signal transmitted through the differential transmission line pair 12, and the vertical axis indicates the degree to which the current component of each mode is attenuated in the filter region 10. COM indicates how the common mode signal is attenuated, and DIF indicates how the differential mode signal is attenuated. As apparent from FIG. 5, in the high frequency band of 1 GHz or more, the attenuation of the differential mode signal is negligible, and the common mode signal is attenuated over a relatively wide bandwidth.

According to the embodiment of the present invention, the second wiring layer adjacent to the first wiring layer including the differential transmission line pair has a non-symmetrical shape with respect to the symmetry plane of the differential transmission line pair. Since the conductor region is included in the second wiring layer, the inductor / capacitance formed in the non-conductor region and the capacitance of the differential transmission line pair can be efficiently resonated. In addition, since the inductor / capacitance formed in the non-conductor region and the capacitance of the differential transmission line pair are efficiently resonated, the impedance in the common mode can be increased.

Also, since the influence of the common mode is reduced, the common mode signal can be filtered over a wide bandwidth for a high frequency signal of 1 GHz or more. Further, although the impedance in the common mode is increased, the impedance in the differential mode is not increased, so that the differential mode signal can be maintained. Further, since the common mode signal is attenuated and the differential mode signal is maintained, the transmission quality can be improved.

(Example 2)
Next, a second embodiment of the present invention will be described. As in the first embodiment, the second embodiment also relates to a wiring board including a differential transmission line pair. Also in the second embodiment, in order to reduce the influence of the common mode on the differential transmission line pair, the second wiring layer includes a plurality of straight slot-shaped non-conductor regions. In Example 1, the length, width, and shape of each non-conductor region are designed to be the same. On the other hand, in Example 2, a plurality of types of lengths of each non-conductor region are defined. By defining a plurality of types of length of each non-conductor region, it becomes easy to set the inductor / capacitance of the non-conductor region to a desired value. As a result, it becomes easy to set the frequency band that can reduce the common mode signal in the frequency band of the signal to be transmitted. The wiring board 100 according to the second embodiment is the same type as that shown in FIG. 1, and the cross section of the filter region 10 is the same type as that shown in FIG.

FIG. 6 is a top view of the filter region 10 according to the second embodiment of the present invention. Here, in the direction perpendicular to the transmission direction of the differential transmission line pair 12, the lengths of the first non-conductor region 20a, the second non-conductor region 20b, the eleventh non-conductor region 20k, and the twelfth non-conductor region 20l remain. This is longer than the length of the non-conductor region 20 (20a to 20l). That is, there are two types of lengths of the non-conductor region 20, and the longer non-conductor region 20 is disposed on the end side of the filter region 10.

In addition, the length of the non-conductor region 20 is not limited to two types, and may exist more than that. For example, the non-conductor region 20 may be arranged so as to become longer as it approaches the end side of the filter region 10. Further, the non-conductor region 20 may be arranged so as to be shorter as it is closer to the end side of the filter region 10. Furthermore, in the transmission direction of the differential transmission line pair 12, the widths of the non-conductor regions 20 do not have to be the same, and a plurality of types may be defined. For example, the non-conductor region 20 may be arranged so as to become wider or narrower as it is closer to the end side of the filter region 10. As described above, the length and width of each non-conductor region 20 may be freely set. However, each non-conductor region 20 is required to have a plane-symmetric shape with respect to the symmetry plane. .

According to the embodiment of the present invention, since the linear slot shape having various lengths and widths is used as the non-conductor region, the frequency characteristics of the impedance in the common mode can be adjusted. Further, since the frequency characteristic of the impedance in the common mode is adjusted, the influence of the common mode on the frequency of the signal to be transmitted in the differential transmission line pair can be reduced. In addition, the design can be simplified because only the length and width of the straight slot-shaped non-conductor region are changed.

(Example 3)
Next, a third embodiment of the present invention will be described. As in the first embodiment, the third embodiment also relates to a wiring board provided with a differential transmission line pair. Also in Example 3, in order to reduce the influence of the common mode on the differential transmission line pair, the second wiring layer includes a plurality of straight slot-shaped non-conductor regions. In the third embodiment, the wiring board 100 is the same type as that in FIG. 1, and the cross section of the filter region 10 is the same type as that in FIG. 3, but the difference from the first and second embodiments is a straight slot type. In addition to the non-conductor region, non-conductor regions having different shapes are also arranged in the second wiring layer.

FIG. 7 is a top view of the filter region 10 according to the third embodiment of the present invention. The first non-conductor region 20a, the second non-conductor region 20b, the fifth non-conductor region 20e, and the sixth non-conductor region 20f have a straight slot shape as in FIG. Further, the third non-conductor region 20c and the fourth non-conductor region 20d have a comb-tooth shape instead of a straight slot shape. For this reason, the third non-conductor region 20c and the fourth non-conductor region 20d do not have a plane-symmetric shape with respect to the symmetry plane. That is, the non-conductor region 20 having a shape symmetrical with respect to the symmetry plane and the non-conductor region 20 having no shape symmetrical with respect to the symmetry plane are combined.

According to the embodiment of the present invention, a non-conductive region having a plane-symmetric shape with respect to a plane of symmetry and a non-conductive region having no plane-symmetric shape with respect to the plane of symmetry are combined. On the other hand, the effect of the interaction between the non-conductor region that does not have a plane-symmetric shape and the differential transmission line pair can also be obtained.

Example 4
Next, a fourth embodiment of the present invention will be described. As in the first embodiment, the fourth embodiment also relates to a wiring board including a differential transmission line pair. Also in Example 4, in order to reduce the influence of the common mode on the differential transmission line pair, the second wiring layer includes a plurality of non-conductor regions. The wiring board 100 according to the fourth embodiment is of the same type as that of FIG. 1, and the cross section of the filter region 10 is of the same type as that of FIG. The shape is different from the straight slot shape.

FIG. 8 is a top view of the filter region 10 according to the fourth embodiment of the present invention. As illustrated, a first non-conductor region 20a, a second non-conductor region 20b, a third non-conductor region 20c, a fourth non-conductor region 20d, and a fifth non-conductor region 20e are disposed. Here, the first non-conductor region 20a has an annular shape, and the second non-conductor region 20b to the fifth non-conductor region 20e have a straight slot shape. That is, the first non-conductor region 20a has a shape that is plane-symmetric with respect to the symmetry plane, but has a shape different from the straight slot shape. Note that the shape of the non-conductor region 20 is not limited to an annular shape. For example, it may be a square or a triangle.

According to the embodiment of the present invention, since non-conductor regions having various shapes are used, the degree of freedom in design can be improved. In addition, it is possible to improve the degree of design freedom when designing the shape of the non-conductor region according to the frequency characteristics of the signal to be transmitted in the differential transmission line pair.

(Example 5)
Next, a fifth embodiment of the present invention will be described. As in the first embodiment, the fifth embodiment also relates to a wiring board provided with a differential transmission line pair. Also in Example 5, in order to reduce the influence of the common mode on the differential transmission line pair, the second wiring layer includes a plurality of non-conductor regions. In Example 5, the wiring substrate 100 is the same type as that in FIG. 1, and the cross section of the filter region 10 is the same type as that in FIG. 3, but a non-conductor region having a different shape is formed in the second wiring layer. The case where it is done is shown. These non-conductor regions are plane symmetric with respect to the symmetry plane of the differential transmission line pair, and there are no non-conductor regions on the symmetry plane in the filter region. That is, the shape is separated in the vicinity of the symmetry plane.

FIG. 9 is a top view of the filter region 10 according to the fifth embodiment of the present invention. Here, the first non-conductor region 20a and the second non-conductor region 20b form one combination, and the third non-conductor region 20c and the fourth non-conductor region 20d form another combination. Each non-conductor area | region 20 included in the combination is arrange | positioned so that it may become plane symmetry with respect to a symmetry plane. More specifically, the first non-conductor region 20a and the second non-conductor region 20b have an arc shape, and the third non-conductor region 20c and the fourth non-conductor region 20d have a comb shape. ing.

Also, instead of the arc shape, it may be a part of a square or triangle side. Here, the third non-conductor region 20c and the fourth non-conductor region 20d are provided with three comb teeth. However, it is not necessary to be limited to three comb teeth, and a larger number of comb teeth may be provided. Further, in the third non-conductor region 20c and the fourth non-conductor region 20d, among the three comb teeth, the center comb tooth is thicker than the remaining comb teeth. However, the thickness of the comb teeth may be arbitrary.

According to the embodiment of the present invention, since two non-conductor regions are arranged on both sides of the symmetry plane, the impedance in the common mode can be further increased. In addition, since the impedance in the common mode is further increased, the influence of the common mode can be further reduced. Moreover, since the influence by the common mode is further reduced, the transmission characteristics in the differential transmission line pair can be further improved.

(Example 6)
Next, a sixth embodiment of the present invention will be described. In the sixth embodiment, as in the first embodiment, a plurality of straight slot-shaped non-conductor regions are arranged. Each transmission line in the first embodiment has a uniform line width. On the other hand, each transmission line in Example 6 has a non-uniform line width. The wiring board 100 according to Example 6 is the same type as that in FIG. 1, and the cross section of the filter region 10 is the same type as that in FIG.

FIG. 10 is a top view of the filter region 10 according to the sixth embodiment of the present invention. As shown in the drawing, the arrangement of the conductor region 18 and the non-conductor region 20 in the second wiring layer 8 is the same as that in FIG. Each of the differential transmission line pairs 12 has a non-uniform line width. Here, the line width on the center side is thicker than the line width on both ends of the filter region 10. Although the differential transmission line pair 12 has such a line width, the differential transmission line pair 12 has a plane-symmetric shape with respect to the symmetry plane. The shape of the differential transmission line pair 12 is not limited to FIG. According to the embodiment of the present invention, it is possible to improve the degree of design freedom regarding the shape of the differential transmission line pair.

(Example 7)
Next, a seventh embodiment of the present invention will be described. Until now, only one pair of differential transmission line pairs has been arranged in the first wiring layer. On the other hand, two pairs of differential transmission line pairs are arranged in the first wiring layer of the seventh embodiment. The wiring board 100 according to Example 6 is the same type as that in FIG. 1, and the cross section of the filter region 10 is the same type as that in FIG.

FIG. 11 is a top view of the filter region 10 according to the seventh embodiment of the present invention. As shown in the drawing, the arrangement of the conductor region 18 and the non-conductor region 20 in the second wiring layer 8 is the same as that in FIG. Each of the first differential transmission line pair 60 and the second differential transmission line pair 62 has the same shape as the differential transmission line pair 12 of FIG. These are arranged in the first wiring layer 4 (not shown), and are arranged in plane symmetry with respect to the symmetry plane 64. The non-conductor region 20 has a shape that is plane-symmetric with respect to the plane of symmetry 64. The number of differential transmission line pairs is not limited to “2”, and may be more than that. According to this modification, the degree of freedom in design can be improved with respect to the number of differential transmission line pairs.

(Example 8)
Next, an eighth embodiment of the present invention will be described. Example 8 describes a portable device provided with the wiring board of the present invention. In addition, although the example mounted in a mobile telephone is shown as a portable apparatus, electronic devices, such as a personal digital assistant (PDA), a digital video camera (DVC), a music player, a digital still camera (DSC), may be sufficient, for example. .

FIG. 12 is a perspective view showing the configuration of the mobile phone 1111 according to the eighth embodiment of the present invention. This corresponds to the mobile phone 1111 provided with the wiring board 100 according to any one of the first to seventh embodiments. A cellular phone 1111 has a structure in which a first housing 1112 and a second housing 1114 are connected by a movable portion 1120. The first housing 1112 and the second housing 1114 can be rotated around the movable portion 1120. The first housing 1112 is provided with a display portion 1118 and a speaker portion 1124 for displaying information such as characters and images. The second housing 1114 is provided with an operation portion 1122 such as operation buttons and a microphone portion 1126. The wiring board 100 according to the first embodiment is mounted inside the mobile phone 1111. There is a backlight driving circuit as a light source of a liquid crystal panel employed in the display unit.

FIG. 13 is a partial cross-sectional view of the mobile phone 1111. This is a partial cross-sectional view of the mobile phone 1111 shown in FIG. 12 (cross-sectional view of the first housing 1112). A transmission / reception circuit 1128 and a signal processing circuit 1130 are attached to the wiring board 100. The wiring board 100 includes a differential transmission line pair for exchanging a high frequency signal of 1 GHz or more between the transmission / reception circuit 1128 and the signal processing circuit 1130.

According to the mobile phone 1111 equipped with the wiring substrate 100 according to any one of the first to seventh embodiments, signal transmission between circuit modules included in the mobile phone 1111, for example, between the transmission / reception circuit 1128 and the signal processing circuit 1130. Characteristics, particularly transmission characteristics in a high frequency region of 1 GHz or more can be improved. Therefore, the wiring board 100 according to any of the first to fifth embodiments is particularly preferably used for a portable device that handles a high-frequency signal of 1 GHz or higher.

According to the embodiment of the present invention, the wiring board can be applied to various devices.

The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

Any combination of Examples 1 to 8 is also effective. According to this modification, it is possible to obtain an effect obtained by arbitrarily combining the first to sixth embodiments.

The outline of one embodiment of the present invention is as follows. A wiring board according to an aspect of the present invention includes a first wiring layer including a differential transmission line pair, a second wiring layer including a conductor region, and an insulation provided between the first wiring layer and the second wiring layer. And a layer. The second wiring layer includes a non-conductor region having a plane-symmetric shape in the conductor region with respect to the symmetry plane of the differential transmission line pair in the first wiring layer.

According to this aspect, in the second wiring layer adjacent to the first wiring layer, the second wiring layer includes the non-conductor region having a plane-symmetric shape with respect to the symmetry plane of the differential transmission line pair. It is possible to efficiently resonate the inductor / capacitance formed in the conductor region and the capacitance of the differential transmission line pair, thereby reducing the influence of the common mode.

The non-conductor region included in the second wiring layer may be continuously formed on the symmetry plane of the differential transmission line pair in the first wiring layer.

The differential transmission line pair included in the first wiring layer may have a shape that is plane-symmetric with respect to the plane of symmetry while having a non-uniform line width. In this case, the frequency characteristics of the impedance in the common mode can be adjusted because they have non-uniform line widths.

Another embodiment of the present invention is also a wiring board. The wiring board includes a first wiring layer including a plurality of differential transmission line pairs, a second wiring layer including a conductor region, and an insulating layer provided between the first wiring layer and the second wiring layer. Prepare. The plurality of differential transmission line pairs in the first wiring layer are arranged in plane symmetry with respect to the symmetry plane, and the second wiring layer is in relation to the symmetry plane of the differential transmission line pair in the first wiring layer, A non-conductor region having a plane symmetrical shape is included in the conductor region.

According to this aspect, since the second wiring layer includes the non-conductive region having a plane-symmetric shape in the conductive region, the impedance can be further increased.

2 1st insulation layer, 4 1st wiring layer, 6 2nd insulation layer, 8 2nd wiring layer, 10 filter area, 12 differential transmission line pairs, 18 conductor area, 20 non-conductor area, 22 insulator, 100 wiring Substrate, upper surface of 100a, 102 first semiconductor module, 104 second semiconductor module.

Claims

A first wiring layer including a differential transmission line pair;
A second wiring layer including a conductor region;
An insulating layer provided between the first wiring layer and the second wiring layer;
The wiring substrate, wherein the second wiring layer includes a non-conductor region having a plane-symmetric shape with respect to a symmetry plane of the differential transmission line pair in the first wiring layer in the conductor region.
The wiring board according to claim 1, wherein the non-conductor region included in the second wiring layer is continuously formed on a plane of symmetry of the differential transmission line pair in the first wiring layer.
3. The differential transmission line pair included in the first wiring layer has a plane-symmetric shape with respect to a plane of symmetry while having a non-uniform line width. The wiring board described.
A first wiring layer including a plurality of differential transmission line pairs;
A second wiring layer including a conductor region;
An insulating layer provided between the first wiring layer and the second wiring layer;
The plurality of differential transmission line pairs in the first wiring layer are arranged in plane symmetry with respect to a symmetry plane,
The wiring board, wherein the second wiring layer includes a non-conductor region having a plane-symmetric shape with respect to a symmetry plane of the differential transmission line pair in the first wiring layer in the conductor region.