JP5409171B2 - Wiring board - Google Patents

Description

  The present invention relates to a wiring board.

  In general, high speed and large capacity transmission are becoming prominent in current electronic devices. Accordingly, wiring boards used in electronic devices are required to have a form with less electrical loss in high-frequency transmission. Therefore, particularly in a wiring board having a transmission path for transmitting a high-frequency signal, a plurality of insulating layers 12 are laminated between the surface of the insulating board 11 and a plurality of insulating layers 12 as shown in FIGS. The grounding or power supply conductor layer 13 is provided. Further, a signal external connection pad 15 connected to an external electric circuit board is provided on the lower surface of the insulating substrate 11, and a signal signal connected to the central portion of the signal external connection pad 15 from the upper surface side of the insulating substrate 11. A through conductor 16 is provided. A signal wiring conductor 14 is connected to the upper end of the signal through conductor 16. Further, among the grounding or power supply conductor layers 13, those connected to the same potential are electrically connected by a grounding or power supply through conductor 18 that penetrates the insulating layer 12.

  In such a wiring board, the reflection of the signal at the external connection pad 15 is suppressed by eliminating a sudden drop in characteristic impedance at the external connection pad 15 connected to the signal through conductor 16, and a high-frequency signal is efficiently generated. In order to be able to transmit to the outside, an opening 13a having a size equal to or larger than that of the external connection pad 15 is provided in a region facing the external connection pad 15 in the conductor layer 13 for grounding or power supply. The capacitance formed between the external connection pad 15 connected to the through conductor 16 and the conductor layer 13 for grounding or power supply is reduced.

  However, when the opening 13 a having a size equal to or larger than that of the external connection pad 15 is provided in the region facing the external connection pad 15 in the grounding or power supply conductor layer 13 as described above, the signal through conductor 16 is provided. And the grounding or power supply conductor layer 13 and the grounding or power supply through conductor 18 are reduced, and the characteristic impedance of the signal through conductor 16 is increased. As a result, for example, a high-frequency signal in which the frequency of the signal transmitted through the signal through conductor 16 exceeds 10 GHz makes it difficult to transmit the signal satisfactorily.

  Therefore, as shown in FIGS. 13 and 14, a wiring board is proposed in which the signal through conductor 16 is connected to the outer peripheral portion of the external connection pad 15. When the signal through conductor 16 is connected to the outer peripheral portion of the external connection pad 15, the signal through conductor 16 comes close to the ground or power source conductor layer 13. By arranging a plurality of grounding or power supply through conductors 18 at positions near the signal through conductors 16 in the power supply conductor layer 13, the signal through conductors 16 and the grounding or power supply conductor layer 13 are arranged. In addition, since it is possible to prevent a decrease in the capacitance between the grounding conductor or the power supply through conductor 18, the impedance of the signal through conductor 14 can be made appropriate to some extent.

  However, even in the wiring board in which the signal through conductor 16 is connected to the outer peripheral portion of the external connection pad 15 in this manner, the signal through conductor 16 is surrounded by the grounding or power supply conductor layer 13 and Since the grounding or power supply through conductors 18 are not surrounded at equal positions with respect to the signal through conductors 16, the signal through conductors 16 and the corresponding conductor layers 13 and through conductors 18 are transmitted. The transmission position is biased in the signal to be transmitted, and as a result, in the case of an ultra-high frequency signal in which the frequency of the signal transmitted through the signal through conductor 16 exceeds 30 GHz, the transmission loss increases and the signal is transmitted satisfactorily. Becomes difficult.

JP 2003-273525 A

  It is an object of the present invention to reduce the signal transmission loss and improve the signal even if the signal transmitted through the signal through conductor and the external connection pad connected to the through conductor is an extremely high frequency exceeding 30 GHz. An object of the present invention is to provide a wiring board capable of transmission.

  The wiring board of the present invention includes an insulating substrate formed by laminating a plurality of insulating layers, an external connection pad formed on the lower surface of the insulating substrate, and a plurality of the insulating layers penetrating from the upper surface side to the external connection pad. A signal through conductor that is led out vertically in the vicinity of the signal, a connection conductor that connects a lower end of the signal through conductor and the external connection pad, and the signal through conductor disposed between the plurality of insulating layers. The signal through conductor has a first opening that passes through the center at a position corresponding to, and a second opening that is equal to or larger than the external connection pad at a position facing the external connection pad. Arranged at equal distances from the signal through conductors to connect the grounding or power supply conductor layers to the grounding or power supply conductor layers and the insulating layer around the first opening. For multiple grounding or power supply It is characterized in that formed by and a through conductor.

  According to the wiring substrate of the present invention, the grounding or power supply conductor layer disposed between the insulating layers is provided with the first opening through which the signal through conductor penetrates the center, and the periphery of the first opening Since the plurality of grounding or power supply through conductors are arranged at an equal distance from the signal through conductors so that the grounding or power supply conductor layers are connected to the insulating layer of the first, The grounding or power supply conductor layer surrounding the signal through conductor and the insulating layer around the first opening are provided at an equal distance from the signal through conductor through the opening of the signal. With multiple grounding or power supply through conductors, a pseudo-coaxial structure can be obtained for the signal through conductors, and the characteristic impedance of the signal through conductors can be matched very well, and at the same time For power supply or power supply Since a second opening having a size equal to or larger than that of the external connection pad is formed at a position facing the external connection pad in the layer, it is provided between the external connection pad and the conductor layer for grounding or power supply. The formed capacitance can be reduced to match the characteristic impedance of the external connection pad. Therefore, even if the signal transmitted through the signal through conductor and the external connection pad connected to the through conductor is an ultra-high frequency exceeding 30 GHz, it is possible to reduce the signal transmission loss and to transmit the signal satisfactorily. it can.

FIG. 1 is a schematic top view of an essential part showing an example of an embodiment of a wiring board according to the present invention. 2 is a schematic cross-sectional view of a main part of the wiring board shown in FIG. FIG. 3 is a schematic top view of a main part showing another example of the embodiment of the wiring board of the present invention. FIG. 4 is a schematic cross-sectional view of a main part of the wiring board shown in FIG. FIG. 5 is a perspective view showing a simulation model according to the present invention. 6 is a partial cross-sectional perspective view showing the model shown in FIG. FIG. 7 is a perspective view showing a simulation model for comparison. FIG. 8 is a partial cross-sectional perspective view showing the model shown in FIG. FIG. 9 is a graph of simulation results of the models shown in FIGS. FIG. 10 is a graph showing a result of simulating the models shown in FIGS. FIG. 11 is a schematic top view of an essential part showing an example of a conventional wiring board. 12 is a schematic cross-sectional view of a main part of the wiring board shown in FIG. FIG. 13 is a schematic top view of a main part showing another example of a conventional wiring board. 14 is a schematic cross-sectional view of a main part of the wiring board shown in FIG.

  Next, an example of an embodiment of a wiring board according to the present invention will be described with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the wiring board of this example has a plurality of grounding or power supply conductor layers 3 between the surface of the insulating substrate 1 formed by laminating a plurality of insulating layers 2 and each insulating layer 2. Is provided. The insulating layer 2 is made of, for example, a fiber-reinforced insulating resin material obtained by impregnating a glass cloth with a thermosetting resin or a filler-containing insulating resin material obtained by dispersing an inorganic insulating filler such as silicon oxide in a thermosetting resin. The conductor layer 3 is formed by depositing a conductive material made of copper foil or a copper plating layer on each insulating layer 2 in a predetermined pattern. In FIGS. 1 and 2, only the main part of the wiring board of this example is schematically shown.

  A signal wiring conductor 4 connected to a signal electrode of an electronic component mounted on the wiring board of this example is formed on the upper surface of the insulating substrate 1, and an external electric circuit is formed on the lower surface of the insulating substrate 1. A signal external connection pad 5 connected to the substrate is formed. The signal wiring conductor 4 and the external connection pad 5 are formed of the signal through conductor 6 and the insulating substrate 1 penetrating each insulating layer 3. They are electrically connected by a signal connection conductor 7 provided on the lower surface. These wiring conductors 4 and external connection pads 5 as well as through conductors 6 and connection conductors 7 have a predetermined pattern in each insulating layer 2 made of a conductive material made of copper foil or a copper plating layer, like the conductor layer 3 for grounding or power supply. It is formed by making it adhere to.

  The grounding or power supply conductor layer 3 is formed with a circular first opening 3a through which the signal through conductor 6 passes through the center at a position corresponding to the signal through conductor 6 and externally. A circular second opening 3b having a size equal to or larger than that of the external connection pad 5 is provided in a region facing the connection pad 5, and the first opening 3a and the second opening 3b are separated from each other. doing.

  Further, a plurality of grounding or power supply terminals disposed equidistantly from the signal through conductor 6 so as to connect the grounding or power supply conductor layers 3 to the insulating layer 2 around the first opening 3a. The through conductors 8 are arranged so as to surround the signal through conductors 6. The first opening 3a and the grounding or power supply penetrating conductor 8 are arranged in a positional relationship that gives a predetermined characteristic impedance to the signal penetrating conductor 6 by a pseudo-coaxial structure. The characteristic impedance at 6 is very well matched. Since the first opening 3a is thus separated from the second opening 3b, a pseudo-coaxial structure having a specific impedance can be easily provided to the signal through conductor 6.

  Further, the second opening 3b having a size equal to or larger than that of the external connection pad 5 is formed in the grounding or power supply conductor layer 3 at a position corresponding to the external connection pad 5. The capacitance formed between the external connection pad 5 and the grounding or power supply conductor layer 3 is reduced. As a result, the characteristic impedance in the external connection pad 5 is satisfactorily matched, and signal reflection at the external connection pad 5 is suppressed.

  Therefore, according to the wiring board of the present invention, even if the signal transmitted through the signal through conductor 6 and the external connection pad 5 connected thereto is an ultrahigh frequency exceeding 30 GHz, the loss of the signal is extremely small. The signal can be transmitted satisfactorily. The present invention is not limited to an example of 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 example of the embodiment, the signal Although the example in which the through conductor 6 and the external connection pad 5 are connected by the connection conductor 7 provided on the lower surface of the insulating substrate 1 is shown, for example, as shown in FIGS. 3 and 4, the signal through conductor 6 and the external connection are connected. The pad 5 may be connected by a connection conductor 7 provided between the insulating layers 2 near the lower surface of the insulating substrate 1. In this case, by providing the grounding or power supply conductor layer 3 on the lower surface of the insulating substrate 11 facing the connection conductor 7, it is easy to match the characteristic impedance of the connection conductor 7 and to the outside of the connection conductor 7. It is possible to strengthen the shield.

  In order to verify the effect of the present invention, an analytical model according to the present invention and an analytical model for comparison were created, and a simulation was performed using an electromagnetic field simulator HFSS manufactured by Ansoft.

  First, an analysis model according to the present invention will be described. As shown in FIGS. 5 and 6, the analysis model according to the present invention is a conductor for grounding or power supply between the upper and lower surfaces of an insulating substrate 1 formed by stacking eight insulating layers (not shown) and each insulating layer. Nine layers 3 were provided. In FIG. 5, the uppermost conductor layer 3 is indicated by a dotted line. A circular land 4 having a diameter of 120 μm was provided on the upper surface of the insulating substrate 1, and an opening 3 a ′ having a diameter of 260 mm having the same center as that of the land 4 was formed in the uppermost conductor layer 3. Further, an external connection pad 5 having a diameter of 620 μm is provided on the lower surface of the insulating substrate 1, and each grounding or power supply conductor layer 3 except for the uppermost conductor layer 3 has a diameter in a region corresponding to the external connection pad 5. The opening 3b of 880 mm is provided so that the center of the external connection pad 5 and the center of the opening 3b are aligned on the same axis. Further, a signal through conductor 6 connected to the center of the lower surface of the uppermost land 4 and penetrating through the insulating layer from the lowermost layer to the second insulating layer is interposed via a land having the same dimensions as the uppermost land 4. And an opening 3 a having a diameter of 520 μm is formed in a region corresponding to the through conductor 6 in each conductor layer 3 excluding the uppermost layer and the second lowest conductor layer 3. The center of the opening 3a and the center of the opening 3a are arranged on the same axis, and the grounding or power supply conductor layer 3 is connected to the vicinity of the opening 3a so that the signal through conductor 6 is about 50Ω. A grounding or power supply through conductor 8 is provided in each insulating layer so as to provide a characteristic impedance of 5 mm. Further, a connection conductor 7 having a width of 28 μm is provided from the land connected to the lower end of the stacked through conductors 6 to the end of the external connection pad 5, and the land 4 is connected to the end of the connection conductor 7 on the external connection pad 5 side. A land having the same diameter was provided, and the land and the external connection pad 5 were connected by a signal through conductor 6 '. A gap surrounding the connection conductor 7 with a width of 82 μm was provided in the conductor layer 3 around the connection conductor 7.

  Next, an analysis model for comparison will be described. As shown in FIGS. 7 and 8, the analysis model for comparison has the same layer configuration as the analysis model according to the present invention described above, and is provided on the insulating substrate 11 formed by stacking eight insulating layers (not shown). Nine grounding or power supply conductor layers 13 were provided between the lower surface and each insulating layer. A circular land 14 having a diameter of 120 μm was provided on the upper surface of the insulating substrate 11, and an opening 13 a ′ having a diameter of 260 mm having the same center as the land 14 was formed in the uppermost conductor layer 13. An external connection pad 15 having a diameter of 620 μm is provided on the lower surface of the insulating substrate 11, and each grounding or power supply conductor layer 13 except for the uppermost conductor layer 13 has a diameter in a region corresponding to the external connection pad 15. The opening portion 13b of 880 mm is provided so that the center of the external connection pad 15 and the center of the opening portion 13b are aligned on the same axis. Further, a through conductor 14 ′ connected to the uppermost land 14 is provided in the uppermost insulating layer, and a connecting conductor having a width of 28 μm from the land connected to the through conductor 14 ′ to a position corresponding to the end of the external connection pad 15. 18 and a land having the same diameter as the land 14 at the end of the connection conductor 7 on the external connection pad 15 side, and the land and the external connection pad 15 are connected to each insulating layer via a land having the same diameter as the land 14. The signal through conductors 16 are arranged so as to be stacked vertically. A gap surrounding the connection conductor 18 with a width of 82 μm was provided in the conductor layer 13 around the connection conductor 18. Further, the grounding or power supply through conductors 18 that surround the signal through conductors 16 at an equal distance from six sides so as to connect the grounding or power supply conductor layers 13 to each other in the vicinity of the opening 3b are formed in the respective insulating layers. Provided.

  FIG. 9 and FIG. 10 are graphs showing frequency characteristics with respect to signal transmission loss and reflection loss, respectively, when simulation is performed using the model according to the present invention and the model for comparison. In the simulation, the thickness of each insulating layer constituting the insulating substrate is 33 μm, the relative dielectric constant is 3.35, the dielectric loss tangent is 0.018, the thickness of each conductor layer is 15 μm, and the upper end diameter of the through conductor is 53 μm. The lower end diameter was 65 μm, and the conductivity was 32000000 S / m.

  In the graphs shown in FIGS. 9 and 10, S21 indicated by a solid line indicates a frequency characteristic with respect to a signal transmission loss, and S11 indicated by a dotted line indicates a frequency characteristic with respect to a signal reflection loss. As can be seen from the graph of the simulation result of the model according to the present invention shown in FIG. 9, in the model according to the present invention, the signal reflection loss is −20 dB or less up to the region of about 50 GHz, and the signal is transmitted to the region of about 45 GHz. It can be seen that the loss is -0.5 dB or more. Therefore, even at an ultrahigh frequency exceeding 30 GHz, the signal can be transmitted satisfactorily with very little loss of signal. On the other hand, as can be seen from the graph of the simulation result of the model for comparison shown in FIG. 10, in the model for comparison, the signal reflection loss exceeds −20 dB in the region exceeding about 15 GHz, and about It can be seen that the signal transmission loss is −0.5 dB or less in the region exceeding the 30 GHz region. Therefore, at a long high frequency exceeding 30 GHz, the loss of the signal becomes large and the signal cannot be transmitted satisfactorily.

DESCRIPTION OF SYMBOLS 1 Insulation board | substrate 2 Insulation layer 3 Grounding or power supply conductor layer 5 External connection pad 6 Signal through conductor 7 Connection conductor 8 Grounding or power supply through conductor

Claims (1)

An insulating substrate formed by laminating a plurality of insulating layers, an external connection pad formed on the lower surface of the insulating substrate, and a plurality of the insulating layers are penetrated to be perpendicular to the vicinity of the external connection pad from the upper surface side. A signal through conductor, a connection conductor connecting the lower end of the signal through conductor and the external connection pad, and a plurality of the insulating layers, the through hole at a position corresponding to the signal through conductor A plurality of conductor layers for grounding or power supply having a first opening through which a conductor penetrates the center and a second opening having a size equal to or larger than that of the external connection pad at a position facing the external connection pad And a plurality of grounding or power supply terminals arranged at equal distances from the signal through conductors so as to connect the grounding or power supply conductor layers to the insulating layer around the first opening. formed SQLDESC_BASE_TABLE_NAME This and a through conductor Wiring board the connection conductor, characterized in Rukoto the lower surface wherein provided in the insulating layers in the vicinity, and has conductor layers for grounding or for power supply to the lower surface opposite to the connection conductor is provided.

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