JP2012248797A - Wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board in which the impedance of a signal through conductor connected with an electrode can be matched.SOLUTION: The wiring board 1 comprises: an insulating substrate 2; a signal wiring layer 3; an electrode 5; a plurality of ground wiring layers 4; a signal through conductor 6; and a plurality of ground through conductors 7. At least the aperture 4b of a ground wiring layer 4 closest to the other principal surface out of the apertures in a plurality of ground wiring layers 4 is larger than the electrode 5 in the plan view. A connection conductor 6c provided corresponding to the first aperture out of a plurality of connection conductors is larger than a connection conductor 6b provided corresponding to an aperture 4a that is smaller than the aperture 6b out of the apertures in the plurality of ground wiring layers 4.

Description

  The present invention relates to a wiring board on which electronic components such as a semiconductor element with increased speed are mounted.

  By increasing the operation speed of the semiconductor element, a high-speed signal propagates in the wiring board on a wiring board on which electronic components such as the semiconductor element are mounted. When a high-speed signal propagates in the wiring board, there is a problem that the signal quality deteriorates due to reflection and attenuation of the signal and causes malfunction of the semiconductor element and the system. Therefore, in the conventional wiring board, as shown in FIG. 6, the signal through layer 66 and the signal through conductor 66 in the wiring board 61 are formed by surrounding the signal through conductor 66 with the ground through conductor 67 to form a pseudo coaxial structure. Reducing the discontinuity of the characteristic impedance is performed.

  Further, the characteristics are determined by the capacitance component generated between the electrode 65 for connection to the external circuit of the wiring board 61 and the ground wiring layer 64 in the wiring board 61, which is electrically connected to one end of the signal through conductor 66. There was a problem that the impedance was lowered.

  To solve such a problem, as shown in FIG. 6, the opening diameter of the opening 64a provided in the ground wiring layer 64 so as to surround the signal through conductor 66 is made larger than the diameter of the electrode 65, There is a wiring board in which unnecessary capacitance components are suppressed by eliminating the overlap between 65 and the ground wiring layer 64 (see, for example, Patent Document 1). In addition, there is a wiring board in which the effective inductance is increased by making the diameter of the grounding through conductor 67 closest to the electrode 65 smaller than other through conductors, and an unnecessary capacitance component is offset by the increased effective inductance. (For example, see Patent Document 2).

Japanese Patent Laid-Open No. 2001-160598 JP 2008-251784

  However, in the wiring board having a pseudo-coaxial structure, when the opening 64b provided in the ground wiring layer 64 closest to the electrode 65 is enlarged as shown in the example shown in FIG. 6, it is connected to the ground wiring layer 64 outside the opening 64b. The ground through conductor 67 surrounding the signal through conductor 66 is separated from the signal through conductor 66, which increases the characteristic impedance and makes it difficult to transmit high-speed signals from 25 Gbps to 40 Gbps. There was a problem of becoming. As a countermeasure, it is conceivable to increase the diameter of the signal through conductor that penetrates the insulating layer positioned above and below the ground wiring layer having a large opening so as to match the characteristic impedance. The presence of the conductor has the following problems. This was the same even when the diameter of the grounding through conductor closest to the electrode was made smaller than that of the other through conductors.

For example, if the insulating substrate is a wiring substrate made of ceramic, a method for forming a via conductor on the wiring substrate is to fill a through hole formed in a ceramic green sheet serving as an insulating layer with a conductive paste serving as a through conductor. In general, it goes through a manufacturing process of firing. Here, in order to suppress cracks and the like generated around the via conductor due to the difference in shrinkage behavior between the via conductor and the ceramic serving as the insulating substrate, ceramic powder is added to the conductor paste forming the through conductor. It is. However, since the conductive paste to which ceramic powder is added at the same ratio is simultaneously filled into through-holes with different diameters, the through-conductors with small diameters increase the electrical resistance, while the through-conductors with large diameters Since there is a large absolute amount of conductor components with good conductivity, the shrinkage behavior changes during firing, and the through conductor with a large diameter increases the absolute value of thermal expansion, so when it is cooled after firing, In some cases, cracks are likely to occur.

  Also, in the wiring board manufacturing process, when filling through holes with different diameters under the same conditions, underfill of the conductors in the through holes for through conductors, and poor filling due to overfilling are likely to occur. Met. When processing through holes for through conductors in an insulating layer, it may be difficult to form through holes with different diameters under the same conditions, and molds and processing conditions corresponding to each diameter are prepared. As a result, labor and cost required for processing increase. For this reason, there has been a problem that the manufacturing yield of the wiring board is reduced and the cost of the product is increased.

As another measure, the signal through conductor that penetrates the insulating layer located above and below the ground wiring layer having a large opening is formed of a plurality of through conductors, and the diameter of the signal through conductor is increased by simulating the characteristic. Although it is conceivable to match the impedance, there is a problem that a tool and labor for processing a plurality of through conductors forming the signal through conductor cause an increase in manufacturing cost. Furthermore, in the continuity test during wiring board manufacture, if one of the signal through conductors is disconnected due to poor connection, the characteristic impedance changes and the transmission characteristics deteriorate. Since the remaining signal through conductors are conductive, there is a problem that they cannot be determined as defective products.

  According to one aspect of the present invention, a wiring board includes an insulating substrate in which a plurality of insulating layers are stacked, a signal wiring layer formed inside or on one main surface of the insulating substrate, and the other main surface of the insulating substrate. Formed electrodes, a plurality of ground wiring layers formed between a plurality of insulating layers and having openings, through the plurality of insulating layers through the openings and having one end electrically connected to the signal wiring layer, etc. A signal through conductor including a plurality of through conductors connected to an electrode and connected to each other and a plurality of connecting conductors provided between the plurality of through conductors, and a plurality of insulating layers so as to surround the signal through conductor And a plurality of ground through conductors that pass through and are connected to the ground wiring layer outside the opening. Of the openings of the plurality of ground conductor layers, at least the first opening of the ground wiring layer closest to the other main surface is larger than the electrode in plan view. The first connection conductor provided corresponding to the first opening among the plurality of connection conductors corresponds to the second opening smaller than the first opening among the openings of the plurality of ground conductor layers. Larger than the second connection conductor provided.

  In the wiring board according to one aspect of the present invention, the first opening of the ground wiring layer closest to at least the other main surface among the openings of the plurality of ground conductor layers is larger than the electrode in plan view, and has a plurality of connections. The first connection conductor provided corresponding to the first opening among the conductors is provided corresponding to the second opening smaller than the first opening among the openings of the plurality of ground conductor layers. By being larger than the second connecting conductor formed, it is possible to eliminate the overlap between the ground wiring layer closest to the other main surface and the electrode, and to occur between the ground wiring layer closest to the other main surface and the electrode. Unnecessary capacitance can be reduced, and the parasitic capacitance of the first connection conductor is added to the signal through conductor, which is the same as when the diameter of the signal through conductor is artificially large. To suppress It can, characteristic impedance at a portion close to the electrode is aligned. Therefore, even if a high-frequency signal is transmitted, the wiring board is less deteriorated.

It is sectional drawing which shows an example of embodiment of the wiring board of this invention. It is sectional drawing which expands and shows the A section of FIG. (A) is sectional drawing in the AA line of FIG. 2, (b) is sectional drawing in the BB line of FIG. It is sectional drawing which expands and shows the principal part of the other example of embodiment of the wiring board of this invention. It is a graph which shows the transmission characteristic of the wiring board of this invention. It is sectional drawing which shows the conventional wiring board.

  Hereinafter, a wiring board in an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 schematically shows a wiring board 1 of the present invention. The number and thickness of insulating layers 2a to 2h of an insulating substrate 2, signal wiring layers 3, ground wiring layers 4, openings 4a, large openings. The size and arrangement of the portion 4b, the electrode 5, the signal through conductor 6, the ground through conductor 7, and the surface wiring layer 8 are set according to the characteristics required for the wiring board 1. In addition, a power supply conductor layer and a power supply through conductor are also formed on the wiring board 1, but are omitted in FIG.

  In the example shown in FIG. 1, the insulating substrate 2 is composed of eight insulating layers 2 a to 2 h, and the signal wiring layer 3, the ground wiring layer 4, the signal through conductor 6, and the ground through conductor 7 inside the insulating substrate 2. Is formed. Of the main surface of the insulating substrate 2, a surface wiring layer 8 is formed on one main surface (upper surface in FIG. 1), and an electrode 5 is formed on the other main surface (lower surface in FIG. 1). In the example illustrated in FIG. 1, the surface wiring layer 8 is illustrated as an example of a connection pad to which a terminal of a semiconductor element is connected. The electrode 5 is for electrical connection to an external circuit board or the like via a bonding material such as solder or a pin. The surface wiring layer 8 and the electrode 5 are connected by a signal wiring layer 3, a ground wiring layer 4, a signal through conductor 6, and a ground through conductor 7 formed inside the insulating substrate 2.

In the example shown in FIG. 1, the signal wiring layer 3 is formed between the insulating layers 2c and 2d inside the insulating substrate 2, and the insulating layer 2b is sandwiched between the signal wiring layers 3 via the insulating layers 2c and 2d. , 2c and between the insulating layers 2d, 2e, a wide-area ground wiring layer 4 is formed to form a so-called stripline structure. By adopting the strip line structure as described above, the signal wiring layer 3 sets the wiring width of the signal wiring layer 3 and the thicknesses of the insulating layers 2c and 2d interposed between the signal wiring layer 3 and the ground wiring layer 4. Thus, the characteristic impedance can be set to an arbitrary value, generally 50Ω. With the signal wiring layer 3 matched with the characteristic impedance, it is possible to obtain the wiring substrate 1 having good transmission characteristics.

  The signal wiring layer 3 only needs to have a structure suitable for transmitting a high-frequency signal, and is not limited to the strip line as described above. For example, a differential line structure composed of two parallel line conductors may be used. In this case, a quasi-coaxial structure like the wiring board of the present invention may be formed between each of the two line conductors and the electrode 5. A microstrip line or a coplanar line structure may be used.

Further, signal transmission in the thickness direction of the wiring board 1 is performed by the signal through conductor 6. The signal through conductor 6 is formed by a first connecting conductor 6b and a second connecting conductor 6c that connect the through conductor 6a formed in the insulating layer 2 and the upper and lower through conductors 6a formed between the insulating layers 2. Yes. One end of the signal through conductor 6 is electrically connected to the signal wiring layer 3, and the other end is connected to the electrode 5 through the insulating layers 2 d to 2 h. The ground wiring layer 4 formed between the insulating layers 2d and 2e, the insulating layers 2e and 2f, and the insulating layers 2g and 2h also penetrates, but the ground wiring layer 4 is formed by forming an opening 4a in the ground wiring layer 4. Is insulated. Each opening 4a is larger than the diameter of the signal through conductor 6a, and the inner periphery of the opening 4a is provided away from the outer peripheral surface of the signal through conductor 6a.

  A plurality of ground penetrating conductors 7 that connect to the ground wiring layer 4 outside the opening 4a and penetrate the insulating layers 2c to 2h are provided so as to surround the signal penetrating conductor 6a. Such a signal through conductor 6 and a plurality of ground through conductors 7 around it constitute a pseudo coaxial line. By having such a pseudo-coaxial structure, the signal through conductor 6 sets the characteristic impedance of the signal through conductor 6 to an arbitrary value by setting the diameter and the distance from the ground through conductor 7. be able to.

  In the wiring board of the present invention, as in the example shown in FIGS. 1 and 2, the opening 4a of the ground wiring layer 4 closest to the other main surface of the insulating substrate 2 where at least the electrode 5 is formed is seen in a plan view. The large opening 4 b is larger than the electrode 5. By arranging the electrode 5 in the large opening 4b in a plan view, at least the lowermost ground wiring layer 4 and the electrode 5 are not overlapped, so that unnecessary capacitance generated between them is suppressed. Can do. In the example shown in FIGS. 1 and 2, only the opening portion of the ground wiring layer 4 at the lowest layer is a large opening portion 4b, but it is further away from the electrode 5 depending on the thickness and relative dielectric constant of the insulating layers 2e to 2f. The opening 4a of the ground wiring layer 4 may also be a large opening 4b to further suppress unnecessary capacitance generated between the ground wiring layer 4 and the electrode 5. Normally, if at least the opening 4a of the lowermost ground wiring layer 4 is a large opening 4b, unnecessary capacitance components can be reduced to the extent that they do not affect the characteristic impedance. Thus, the pseudo-coaxial line structure has a normal opening 4a, a through conductor 6a, and a first connecting conductor 6b until halfway, and a large opening 4b, a through conductor 6a, and a second connection on the side close to the electrode 5. The connection conductor 6c is provided. By doing in this way, in the part away from the electrode 5 in the inside of the wiring board 1, since the space which provides the large opening part 4b is unnecessary, the freedom degree of arrangement | positioning of surrounding wiring becomes high by that much.

In the wiring board of the present invention, the through wiring conductor 6a that penetrates the insulating layers 2f to 2h positioned above and below the ground wiring layer 4 having the large opening 4b, in other words, outside the large opening 4b, the ground wiring layer 4 is provided. The through conductor 6a surrounded by the ground through conductor 7 connected to is connected through a second connection conductor 6c having a diameter larger than that of the first connection conductor. If the large opening 4b is provided in the ground wiring layer 4, the distance between the ground through conductor 7 connected to the ground wiring layer 4 outside the large opening 4b and the through conductor 6a surrounded by them increases. The characteristic impedance of the through conductor 6a is increased, but the through conductor 6a is connected to the through conductor 6a by connecting the through conductor 6a via the second connection conductor 6c having a diameter larger than that of the first connection conductor 6b. Since the parasitic capacitance of the second connection conductor 6c is added, the diameter of the through conductor 6a is artificially increased, so that an increase in the characteristic impedance of the signal through conductor 6 can be suppressed. As a result, the wiring substrate 1 is capable of transmitting a high-frequency signal with matched characteristic impedance even at a portion close to the electrode 5. At this time, the characteristic impedance of the signal through conductor 6a penetrating through the insulating layers 2f to 2h positioned above and below the ground wiring layer 4 having the opening 4b is the diameter of the second connecting conductor and the through conductor 6a and the ground through conductor 7. It can be set to any value depending on the distance between.

  In the example shown in FIG. 3A, the through conductor 6a passing through the opening 4a of the ground conductor layer 4 is the first connecting conductor 6b at a position away from the other main surface of the wiring board 1 on which the electrode 5 is formed. Are connected and pass through the large opening 4b formed in the ground wiring layer 4 closest to the other main surface of the insulating substrate 2 on which the electrode 5 is formed, as in the example shown in FIG. The conductor 6a is connected to a second connection conductor 6c having a diameter larger than that of the first connection conductor.

As shown in FIG. 3, the opening 4a is circular, and a plurality of grounding through conductors 7 are concentrically centered on the through conductor 6a in plan view along the opening 4a outside the opening 4a. It is preferred that they are arranged above. Insulating layers 2f to 2h located above and below the ground wiring layer 4 having the large opening 4b are arranged concentrically around the through conductor 6a outside the large opening 4b. In this case, since the grounding through conductors 7 are arranged concentrically around the signal through conductor 6a, leakage of the transmitted signal can be suppressed in all directions. The wiring board is further reduced in loss. Concentric arrangement means to arrange them at equal intervals on the concentric circles.

  In order to arrange the grounding through conductors 7 so as to surround the through conductors 6a, it is preferable to arrange at least three around the through conductors 6a. More preferably, as shown in FIG. It is preferable to arrange four or more grounding through conductors 7 around the conductor 6a. Further, the grounding through conductors 7 arranged in a concentric circle shape are such that the distance between the two adjacent grounding through conductors 7 and 7 is equal to or less than ¼ of the wavelength of the signal transmitted by the signal through conductor 6. It is preferable because a signal can be prevented from leaking between the ground through conductors 7 and 7.

  The second connecting conductor 6c connected to the penetrating conductor 6a passing through the large opening 4b may have a polygonal shape such as a quadrangle or a hexagon as in the examples shown in FIGS. 4 (a) and 4 (b). In terms of design, the second connection conductor 6c is preferably circular.

  The second connection conductor 6c has a maximum outer dimension larger than that of the first connection conductor 6b. From the viewpoint of design, it is better that the second connection conductor 6c has a larger area than the first connection conductor 6b.

  The distance between the plurality of second connection conductors 6c is ¼ or less of the wavelength of the transmitted signal from the viewpoint of impedance matching.

  The through conductors such as the signal through conductor 6 (through conductor 6a) and the ground through conductor 7 are provided with the first connecting conductor and the first connecting conductor in order to prevent disconnection due to the displacement of the upper and lower insulating layers when the wiring board 1 is manufactured. The diameter of the connecting conductor 2 is preferably larger than the diameter of the through conductor between the upper and lower insulating layers.

The value of the characteristic impedance of the signal through conductor 6 having such a pseudo coaxial structure is 60 to 70Ω, which is higher than the general 50Ω depending on the required transmission characteristics when the frequency of the signal to be transmitted is 10 GHz or more. It is preferable to set the degree. This is because the characteristic impedance of the electrode 5 is lower than 50Ω due to the capacitance generated between the ground wiring layer 4 and the electrode 5, and therefore the characteristic impedance of the signal through conductor 6 having a pseudo coaxial structure is higher than 50Ω. This is because the transmission characteristic can be improved by making the average characteristic impedance from the signal through conductor 6 having the pseudo coaxial structure to the electrode 5 close to 50Ω by setting the value to the value. Similarly, in the case of differential wiring, the transmission characteristics can be improved at a frequency of 10 GHz or more by setting it to about 120 to 140Ω, which is higher than general 100Ω.

Specifically, the dielectric constant of the insulating substrate 2 using differential wiring is 5.8, and the signal distribution through conductor 6
When the diameter of the ground through conductor 7 is 75 μm, four ground through conductors 7 having a diameter of 75 μm are arranged at equal intervals on a concentric circle having a radius of 250 μm from the center of the signal through conductor 6 so as to surround one signal through conductor 6. Is arranged (the distance between the signal through conductor 6 and the ground through conductor 7 is 175 μm), so that the differential impedance can be 50Ω. At this time, the diameter of the first connection conductor may be 175 μm, and the diameter of the opening 4 a of the ground conductor 4 may be 500 μm.

The electrode 5 formed on the other main surface of the insulating substrate 2 has a diameter of 800 μm, and the ground wiring layer 4 located 100 μm from the other main surface is provided with a large opening 4b having a diameter of 1800 μm to reduce unnecessary capacitance. In this case, the through conductor 66a penetrating the insulating layers 62f to 62h located above and below the ground wiring layer 64 having the large opening 64b as shown in FIG. 6 has a diameter of 75 μm and the first connecting conductor 66b. The diameter of the signal through conductor is 125 um, and four ground through conductors 7 are arranged at equal intervals on a concentric circle having a radius of 900 μm from the center of the signal through conductor (distance between the signal through conductor 6 and each of the four ground through conductors 7. 825 μm), the differential impedance value of the signal through conductor 66 of the pseudo coaxial structure in the conventional wiring board is as large as about 90Ω.

  On the other hand, as in the example shown in FIG. 1, the ground wiring layer 4 and the ground through conductor 7 having the large opening 4b similar to the above are positioned above and below the ground wiring layer 4 having the large opening 4b. The characteristic impedance value of the signal through conductor 6 of the pseudo coaxial structure in the wiring board of the present invention in which the diameter of the signal through conductor 6 penetrating the insulating layer 2 is 75 μm and the diameter of the second connecting conductor is 300 μm is about 63Ω. Thus, even if the large opening 4b is provided, an increase in characteristic impedance can be suppressed.

  In addition, the electrical characteristics of the pseudo-coaxial signal through conductors of the wiring board of the present invention and the conventional wiring board were calculated by simulation. FIG. 5 is a graph showing the reflection characteristic (S11) among the transmission characteristics in the simulation result, where the vertical axis represents the reflection amount and the horizontal axis represents the frequency. In FIG. 5, the solid line indicates the characteristic of the wiring board of the present invention, and the broken line indicates the characteristic of the conventional wiring board.

In the simulation model of the wiring board of the present invention, the signal wiring layer 3 is a differential wiring, the wiring width is 55 μm, the distance between the wirings is 175 μm, the thickness is 10 μm, and an insulating layer having a thickness of 100 μm is formed above and below it. A strip line having a differential impedance of 100Ω is obtained by arranging the ground wiring layer 4 through the ground line. From the signal wiring layer 3 to 0.2 mm, the signal through conductor 6 having a diameter of 75 μm, the ground wiring layer 4 having an opening 4a having a diameter of 500 μm, and the first connection conductor 6b having a diameter of 125 μm are formed. As the first pseudo-coaxial structure, 0.6 mm from there to the electrode 5 is the above-described signal through conductor 6a having a diameter of 75 μm and the second connecting conductor 6c, and the diameter is 1800 μm.
The second pseudo-coaxial structure is formed of the ground wiring layer 4 having the large opening 4b.

  On the other hand, in the conventional simulation model of the wiring board, the structure from the signal wiring layer 3 to the electrode 5 is as shown in FIG. A through conductor 66a having a diameter of 75 μm and a first connecting conductor 66b having a diameter of 125 μm were used in the same manner from 63 to the electrode 65.

From FIG. 8, since the characteristic impedance value of the signal through conductor of the conventional wiring board is as high as 90Ω with respect to 50Ω of the signal wiring layer 3, the reflection loss deteriorates at 15 GHz or more.
It can be seen that the wiring loss of the present invention is -15 dB or less up to about 30 GHz, whereas it is -15 dB or more at the GHz or higher. Usually, when the reflection loss is −15 dB or less, there is no problem in transmitting a signal.

  For this reason, it can be said that the wiring board of the present invention is a wiring board capable of transmitting a high-frequency signal in which the characteristic impedance is matched even in a portion close to the electrode 5.

  The insulating layers 2a to 2h of the insulating substrate 2 are made of ceramics such as an aluminum oxide sintered body, an aluminum nitride sintered body, a silicon carbide sintered body, a silicon nitride sintered body, a mullite sintered body, or a glass ceramic. Materials, or composed of electrical insulating materials such as polyimide, epoxy resin, fluororesin, organic resin material such as polynorbornene or benzocyclobutene, or composite insulating material in which ceramic material powder is dispersed in organic resin material It is.

  The insulating layers 2a to 2h are formed by a substrate forming means such as a ceramic green sheet laminating method or an additive method.

  If the insulating substrate 2 is made of, for example, an aluminum oxide sintered body, first, an appropriate organic binder or solvent is added to and mixed with the raw material powder such as aluminum oxide, silicon oxide, calcium oxide or magnesium oxide, and the slurry is mixed. The ceramic green sheet used as the insulating layers 2a-2h is obtained by making this into a sheet shape by a sheet forming method such as a doctor blade method. This ceramic green sheet is cut into an appropriate size, and laminated to prepare a laminated body. The laminated body is fired at a temperature of about 1600 ° C. in a reducing atmosphere to thereby form a plurality of insulating layers 2a to 2h. Is manufactured.

  In the case where the insulating substrate 2 is made of an epoxy resin, for example, first, a substrate made of glass epoxy resin obtained by impregnating a glass fiber woven cloth with an epoxy resin is used as the lowermost insulating layer 2h, and a liquid is formed on the upper surface thereof. The insulating layer 2g is formed by depositing a thermosetting or photosensitive epoxy resin precursor by spin coating or curtain coating, and curing it by heating or irradiating light such as ultraviolet rays. . Furthermore, a plurality of insulating layers 2a to 2f can be formed by repeatedly forming an insulating layer according to the required number of layers thereon.

When the insulating substrate 2 is made of a ceramic material, the signal wiring layers 3, the ground wiring layers 4, the electrodes 5, the signal through conductors 6 (connection conductors 6b and 6c), the ground through conductors 7, and the surface wiring layers 8, etc. For example, it is formed by metallization with a metal powder such as tungsten (W), molybdenum (Mo), molybdenum-manganese (Mo-Mn), copper (Cu), silver (Ag) or silver-palladium (Ag-Pd). If the insulating substrate 2 is made of an organic resin material, for example, copper (Cu), silver (Ag), nickel (Ni), chromium (Cr), titanium (Ti), gold (Au) or It can be formed of a thin film made of a metal material such as niobium (Nb) or an alloy thereof.

If the insulating substrate 2 is made of a ceramic material, the signal through conductor 6 (connection conductors 6b and 6c) and the ground are formed by punching or laser processing the ceramic green sheet with a die in the step of manufacturing the insulating substrate 2 described above. Forming a through hole for the through conductor 7,
The through holes are filled with a metal paste obtained by adding and mixing an appropriate organic binder or solvent to the metal powder, and the signal wiring layer 3, the ground wiring layer 4, and the electrode 5 are formed on the surface of the ceramic green sheet. The metal paste can be printed and applied in a predetermined pattern on the surface wiring layer 8 and fired together with the ceramic green sheet.

If the insulating substrate 2 is made of an organic resin material, the insulating layer formed as described above and the copper layer are formed by employing a thin film forming technique such as an electroless plating method or a vapor deposition method and a photolithography technique. What is necessary is just to produce alternately the wiring conductor comprised. For example, an insulating layer having a through hole is formed using a photosensitive resin, a mask having a predetermined pattern shape is formed on the insulating layer, and the inside of the through hole and the surface of the insulating layer are formed by sputtering, vacuum evaporation, or plating. A metal thin film of a predetermined shape may be formed on Alternatively, after forming a metal thin film on the entire upper surface of the insulating layer without forming a mask, a mask having a predetermined shape may be formed and unnecessary portions may be removed by etching. Alternatively, for example, the signal wiring layer 3, the ground wiring layer 4, the electrode 5 and the surface wiring layer 8 may be formed by processing a metal foil made of copper into a predetermined shape and transferring it onto the insulating layer. Further, the signal through conductor 6 (connection conductors 6b and 6c) and the ground through conductor 7 may be formed by filling a through hole with a paste made of the above metal powder and a binder.

1: Wiring substrate 2: Insulating substrates 2a-2h: Insulating layer 3: Signal wiring layer 4: Ground wiring layer 4a: Opening 4b: Large opening 5: Electrode 6: Signal through conductor 6a: Through conductor 6b: First Connection conductor 6c: Second connection conductor 7: Grounding through conductor 8: Surface wiring layer

Claims (2)

An insulating substrate in which a plurality of insulating layers are laminated;
A signal wiring layer formed inside or one main surface of the insulating substrate;
An electrode formed on the other main surface of the insulating substrate;
A plurality of ground wiring layers formed between the plurality of insulating layers and having openings;
The plurality of insulating layers pass through the opening, one end is electrically connected to the signal wiring layer and the other end is connected to the electrode, and the plurality of connected through conductors and the plurality of throughs A signal through conductor including a plurality of connecting conductors provided between the conductors;
A plurality of grounding through conductors that pass through the plurality of insulating layers so as to surround the signal through conductors and are connected to the grounding wiring layer outside the openings,
The first opening of the ground wiring layer closest to at least the other main surface of the openings of the plurality of ground conductor layers is larger than the electrode in plan view,
Of the plurality of connection conductors, a first connection conductor provided corresponding to the first opening is a second smaller than the first opening among the openings of the plurality of ground conductor layers. A wiring board characterized in that it is larger than the second connection conductor provided corresponding to the opening.   2. The wiring board according to claim 1, wherein the opening has a circular shape, and the plurality of grounding through conductors are arranged on a concentric circle centered on the signal through conductor in a plan view.

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