JP2011035171A - Wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board capable of satisfactorily transmitting a signal by reducing a transmission loss of the signal. <P>SOLUTION: The wiring board includes an external connection pad 16 formed on a lower surface of an insulating substrate 8, a penetration conductor 4 for the signal that passes through a plurality of insulating layers 6 and is vertically connected to the center of the external connection pad 16 from an upper surface side, and a plurality of conductive layers 14 for grounding or for power supply that are disposed among the plurality of insulating layers 6 and have openings 10 through each of which the penetration conductor 4 for the signal passes at a position corresponding to the external connection pad 16. In the conductive layers 14 for grounding or for power supply, a plurality of projections 18 project toward the center of the opening 10 are formed and the upper and lower projections 18 are connected by the penetration conductor 14 for grounding or for power supply passing through each insulating layer 6, and a space between the penetration conductor 14 for grounding or for power supply and the penetration conductor 4 for the signal is expanded toward the side of the external connection pad 16 from an upper surface side. <P>COPYRIGHT: (C)2011,JPO&INPIT

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 line for transmitting a high-frequency signal, a plurality of grounds are provided between the upper and lower surfaces of the insulating substrate 108 formed by laminating a plurality of insulating layers 106 and each insulating layer 106, as shown in FIG. Or a power source conductor layer 114 is provided. In addition, an external connection pad 116 is provided on the lower surface of the insulating substrate 108, and the signal through conductor 104 penetrates the plurality of insulating layers 106 so that the central portion of the external connection pad 116 from the upper surface side of the insulating substrate 108. Connected vertically. A plurality of grounding or power supply conductor layers 114 arranged alternately with the insulating layers 106 have openings 110 on the external connection pads 116 so as to surround the signal through conductors 104 concentrically, The through conductors 112 for grounding or power supply are connected. The signal through conductor 104 is configured by arranging a grounding or power supply conductor layer 114 and a grounding or power supply through conductor 112 through the opening 110 so as to surround the signal through conductor 104. A central conductor of a pseudo coaxial circuit capable of transmitting a high frequency signal is formed.

  In such a wiring substrate, the reflection of the signal at the external connection pad 116 is suppressed by eliminating a sudden drop in characteristic impedance at the external connection pad 116 connected to the signal through conductor 104, and a high-frequency signal is efficiently generated. In order to enable transmission to the outside, the size of the opening 110 formed in the grounding or power supply conductor layer 114 is equal to or larger than the size of the external connection pad 116, thereby connecting to the signal through conductor 104. The capacitance formed between the external connection pad 116 and the grounding or power supply conductor layer 114 is reduced.

  However, when the opening 110 having a size equal to or larger than that of the external connection pad 116 is provided in the region facing the external connection pad 116 in the conductor layer 114 for grounding or power supply as described above, the signal through conductor 104 is provided. And the grounding or power supply conductor layer 114 and the grounding or power supply through conductor 112 are reduced, and the characteristic impedance of the signal through conductor 104 is increased. As a result, for example, in a high-frequency signal in which the frequency of the signal transmitted through the signal through conductor 104 exceeds 10 GHz, it is difficult to transmit the signal satisfactorily.

JP 2003-78065 A

  An object of the present invention is to reduce the signal transmission loss and reduce the signal transmission loss even if the signal transmitted through the signal through conductor and the external connection pad connected to the signal through conductor is an ultra-high frequency exceeding 30 GHz. An object of the present invention is to provide a wiring board that can transmit the signal in a satisfactory manner.

  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 central portion of the external connection pad from the upper surface side through the plurality of insulating layers. And a plurality of grounding or power supply conductors that are vertically connected to each other and have openings that are disposed between the plurality of insulating layers and that pass through the signal through conductors at positions corresponding to the external connection pads. The grounding or power supply conductor layer has a plurality of protrusions protruding toward the center of the opening, and the space between the upper and lower protrusions is They are connected by a grounding or power supply through conductor that penetrates each insulating layer, and the distance between the grounding or power supply through conductor and the signal through conductor increases from the upper surface side to the external connection pad side. It is characterized by being That.

  According to the wiring board of the present invention, the grounding or power supply conductor layer constituting the pseudo-coaxial transmission path for transmitting a high-frequency signal has a plurality of protrusions protruding toward the center of the opening. The characteristic impedance of the signal through conductor can be appropriately adjusted by increasing the capacitance with the signal through conductor. Further, since the distance between the grounding or power supply through conductor and the signal through conductor is increased from the upper surface side toward the external connection pad side, the characteristic impedance of the signal through conductor is reduced to the signal through conductor. Thus, the reflection loss due to a sudden characteristic impedance change from the signal through conductor to the external connection pad can be reduced. Therefore, the reflection loss and transmission loss of the high-frequency signal in the pseudo coaxial circuit are reduced, whereby the high-frequency signal can be transmitted very efficiently.

Fig.1 (a) is sectional drawing which shows the 1st example of embodiment in the wiring board of this invention. FIG. 2 is a plan view of a main part in the first example and the second example of the embodiment of the wiring board of the present invention. FIG. 3 is a plan view of a main part in the first example and the second example of the embodiment of the wiring board of the present invention. FIG. 4 is a cross-sectional view showing a second example of the embodiment of the wiring board of the present invention. FIGS. 5A and 5B are graphs showing simulation results when the model of the first example of the embodiment of the wiring board of the present invention is modeled. FIGS. 6A and 6B are graphs showing simulation results when the model of the first example of the embodiment of the wiring board of the present invention is modeled. FIG. 7 is a cross-sectional view showing a conventional wiring board.

  Next, the 1st example of embodiment in the wiring board of this invention is demonstrated. As shown in FIG. 1, the wiring board of this example has a plurality of grounding or power supply conductor layers 14 between the upper and lower surfaces of an insulating substrate 8 in which a plurality of insulating layers 6 are laminated and the insulating layer 8. Is provided. In addition, an external connection pad 16 is provided on the lower surface of the insulating substrate 8, and the signal through conductor 4 penetrates the plurality of insulating layers 6 so that the central portion of the external connection pad 16 from the upper surface side of the insulating substrate 8. Connected vertically. A plurality of grounding or power supply conductor layers 14 arranged alternately with the insulating layers 6 have openings 10 on the external connection pads 16 so as to surround the signal through conductors 4 in a concentric circle. The through conductors 12 for grounding or power supply are connected.

  The insulating layer 6 is made of a resin-based electrical insulating material. An insulating sheet, epoxy resin, or bismaleimide in which a glass cloth in which glass fiber bundles are woven vertically and horizontally is impregnated with a thermosetting resin such as bismaleimide triazine resin or epoxy resin. An insulating substrate 8 is formed by laminating a plurality of insulating layers 6 by pressurizing and thermosetting an insulating sheet containing a thermosetting resin such as a triazine resin. The thickness of the insulating layer 6 is, for example, 5 to 50 um. The signal through conductor 4, the grounding or power supply conductor layer 14, and the grounding or power supply through conductor 12 are made of copper plating or copper foil. The thickness is 10 to 30 μm. In another example, the through conductors 4 and 12 are made of a conductive paste.

  As shown in FIGS. 2 and 3, the grounding or power supply conductor layer 14 has a plurality of protrusions 18 protruding toward the center of the opening 10, and between the upper and lower protrusions 18. Are connected by a grounding or power supply through conductor 12 that penetrates each insulating layer 6. Thus, the capacitance of the grounding or power supply conductor layer 14 and the grounding or power supply through conductor 12 and the signal through conductor 4 is increased to appropriately adjust the characteristic impedance of the signal through conductor. be able to. Further, the distance between the grounding or power supply through conductor 12 and the signal through conductor 4 increases from the upper surface side toward the external connection pad side 16. As a result, the characteristic characteristic impedance of the signal through conductor 4 can be gradually and gradually changed from the upper end side of the signal through conductor 4 to the external connection pad 14 side. The reflection loss due to a sudden characteristic impedance change in the external connection pad 14 is reduced. Therefore, the reflection loss and transmission loss of the high-frequency signal in the pseudo coaxial circuit are reduced, whereby the high-frequency signal can be transmitted very efficiently.

  Next, a second example of the embodiment of the wiring board of the present invention will be described. As shown in FIG. 4, the wiring substrate of this example is obtained by forming an insulating substrate 8 by laminating a plurality of insulating layers 6 on both upper and lower surfaces of a core substrate 22. The core substrate 22 is formed of an electrically insulating material obtained by impregnating a glass cloth obtained by weaving glass fiber bundles vertically and horizontally with a thermosetting resin such as a bismaleimide triazine resin or an epoxy resin. The insulating layer 6 is made of the same material as the first example described above. The signal through conductor 4 of the core substrate 22 is formed by filling a through hole formed by a drill or a laser with copper plating and a conductive paste.

  In the second example, a plurality of insulating layers 6 each having four layers are formed above and below the core substrate 22. The signal through conductor 4 is connected to the central portion of the external connection pad 16 from the upper surface side through the through hole 20 vertically. The grounding or power supply conductor layer 14 has an opening 10 through which the signal through conductor 4 penetrates at a position corresponding to the external connection pad 16. As shown in FIGS. 2 and 3, the grounding or power supply conductor layer 14 has a plurality of protrusions 18 protruding toward the center of the opening 10, as shown in FIGS. 2 and 3. The protrusions 18 are connected by a grounding or power supply through conductor 12 penetrating each insulating layer 6, and the distance between the grounding or power supply through conductor 12 and the signal through conductor 4 is set. It spreads from the upper surface side toward the external connection pad side 16.

  Here, the frequency characteristics with respect to signal reflection and transmission in the simulation when the first example of the embodiment of the present invention and the conventional example corresponding thereto and the second example and the conventional example corresponding thereto are modeled are shown in FIG. It is shown graphically in a), (b) and FIGS. 6 (a), (b). 5A and 6A are frequency characteristic graphs of reflection loss as viewed from the upper end of the through conductor 4, and FIGS. 5B and 6B are external views from the upper end of the through conductor 4. This is an insertion loss to the connection pad 16 side. In these graphs, the frequency characteristic indicated by the solid line is the result of simulating the model according to the first example or the second example, and the frequency characteristic indicated by the broken line is the result of simulating the model according to the conventional technique.

  As can be seen from FIG. 5A, in the model of the first example, the reflection loss is −20 dB or less until the frequency exceeds 40 GHz, whereas in the conventional model, the reflection loss is reduced when the frequency exceeds 28 GHz. It will exceed -20 dB. Further, as can be seen from FIG. 5 (b), in the model of the first example, the insertion loss is −0.5 dB or more until the frequency exceeds 40 GHz, whereas in the conventional model, the frequency is around 20 GHz. The insertion loss becomes −0.5 dB or less. Therefore, according to the first example of the embodiment of the present invention, it can be seen that a high-frequency signal can be transmitted very efficiently.

  Further, as can be seen from FIG. 6A, in the model of the second example, the reflection loss is −20 dB or less until the frequency exceeds 40 GHz, whereas in the conventional model, the reflection is reflected when the frequency exceeds 12 GHz. The loss exceeds -20 dB. Further, as can be seen from FIG. 6B, in the model of the second example, the insertion loss is −0.5 dB or more up to a frequency of 35 GHz, whereas in the conventional model, the insertion loss is around 25 GHz. Becomes −0.5 dB or less. Therefore, according to the second example of the embodiment of the present invention, it can be seen that a high-frequency signal can be transmitted very efficiently.

  In the model according to the first example of the embodiment of the present invention, in the insulating substrate 8 shown in FIG. 1, the insulating substrate 8 has a relative dielectric constant of 3.3, a thickness of 33 μm, and the external connection pad 16 has a diameter of 620 μm and a thickness of 15 μm, the diameter of the opening 10 is 870 μm, the land diameter of the signal through conductor 4 is 120 μm, the thickness is 15 μm, the diameter of the through conductors 12 and 14 is 65 μm, the inner diameter of the uppermost protrusion 18 is 250 μm, and the second layer from the top The inner diameter of the protrusion 18 is 350 μm, the inner diameter of the protrusion 18 of the third layer from the top is 450 μm, the inner diameter of the protrusion 18 of the fourth layer from the top is 550 μm, and the inner diameter of the protrusions from the fifth to seventh layers is 750 μm. The case where the inner diameter of the lowermost layer was 870 μm was modeled. Further, in the conventional model corresponding to the model of the first example, in the model according to the first example described above, the protrusion 18 projecting into the opening 10 is not provided, and the ground or power supply is provided near the outside of the opening 10. A model with through-conductors was modeled.

  In the model according to the two examples of the embodiment, in the insulating substrate 8 shown in FIG. 4, the insulating substrate 8 has a relative dielectric constant of 3.3, a thickness of 33 μm, a diameter of the external connection pad 16 of 620 μm, and a thickness of 15 μm. The diameter of the opening 10 is 870 μm, the land diameter of the signal through conductor 4 is 120 μm, the thickness is 15 μm, the diameter of the through conductors 12 and 14 is 65 μm, the thickness of the core substrate 22 is 300 μm, and the inner diameter of the uppermost protrusion 18 is 250 μm. The inner diameter of the protrusion of the second layer from the top is 350 μm, the inner diameter of the protrusion 18 of the third layer from the top is 450 μm, the inner diameter of the protrusion of the fourth layer from the top is 550 μm, and the protrusions from the top to the fifth to seventh layers The case where the inner diameter of the portion 18 was 750 μm and the inner diameter of the lowermost layer was 870 μm was modeled. Further, in the conventional model corresponding to the model of the second example, in the model according to the second example described above, the protrusion 18 projecting into the opening 10 is not provided, and the ground or power supply is provided near the outside of the opening 10. A model with through-conductors was modeled.

  As mentioned above, although several examples of embodiment in the wiring board of the present invention were explained, if the wiring board of the present invention is not limited to the example of the embodiment mentioned above and is in the range which does not deviate from the gist of the present invention, Various changes are possible.

DESCRIPTION OF SYMBOLS 4 Signal through conductor 6 Insulating layer 8 Insulating board 10 Opening part 12 Grounding or power supply through conductor 14 Grounding or power supply conductor layer 16 External connection pad 18 Protrusion

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 penetrating from the upper surface side to a central portion of the external connection pad. A plurality of conductor layers for grounding or power supply, which are disposed between the plurality of signal through conductors and a plurality of the insulating layers and have openings through which the signal through conductors penetrate at positions corresponding to the external connection pads. The grounding or power supply conductor layer has a plurality of protrusions protruding toward the center of the opening, and the upper and lower protrusions Are connected by a grounding or power supply through conductor penetrating each of the insulating layers, and an interval between the grounding or power supply through conductor and the signal through conductor is from the upper surface side to the external connection. Spread toward the pad side Wiring board, characterized in that there.

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