JP2003168864A - Multilayer circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of a ringing noise in a multilayer circuit board and to prevent the occurrence of a simultaneous switching noise of a circuit for a power source or a circuit for a ground. <P>SOLUTION: The multilayer circuit board comprises a core board 5 having a through conductor 3 and a connecting land 4 extended from the conductor 3 in an insulating base 2, a multilayer wiring part having a plurality of insulating layers 7 and wiring conductor layers 8 laminated on the surface of the core board 5, and an insulating coating layer 12. An opening 13 having an area of the area or more of the land 4 is formed in a region of a wiring conductor layer 9 opposed to the land 4, and an opening 14 having the area of the area or less of the opening 13 and the area of the sectional area or more of the conductor 3 is formed in a region of the coating layer 12 opposed to the opening 13. Since the electromagnetic bond of the land 4 to the layer 9 is small, the mismatching of the characteristic impedance can be prevented. Since the inductance value of the layer 9 can be reduced, the ringing noise or the simultaneously switching noise can be reduced. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a package for housing a semiconductor element for housing a semiconductor element or an electronic circuit board on which a semiconductor element or an electronic component is mounted. The present invention relates to a multilayer wiring board, and more particularly to a multilayer wiring board having a wiring structure suitable for housing or mounting a semiconductor element operating at high speed. [0002] Conventionally, microprocessors and ASICs
(Application Specific Integrated Circuit) and other electronic components such as semiconductor elements are mounted on a multilayer wiring board used for an electronic circuit board or the like. In forming a wiring conductor for internal wiring, alumina ceramics or the like is used. The insulating layer made of ceramic and the wiring conductor layer made of a high melting point metal such as tungsten (W) are alternately laminated to form a multilayer wiring board. On the other hand, as the demand for improving the information processing capability has increased, the operating speed of the semiconductor element has been increased, and the signal wiring among the wiring conductors for the internal wiring has characteristic impedance matching and crossover between the signal wirings. There has been a demand for improvement of electrical characteristics such as reduction of talk noise. In order to cope with such a demand, the wiring structure of the signal wiring is a strip line structure, and a wide-area power supply wiring layer or a ground (ground) wiring layer is formed above and below the signal wiring via an insulating layer. Was. However, in such a multilayer wiring board, since the insulating layer is made of alumina ceramic or the like having a relative dielectric constant of about 10, the electromagnetic coupling between the signal wirings is increased, so that the crosstalk noise is increased. As a result, there has been a problem that the operation speed of the semiconductor element cannot be increased. Therefore, instead of using alumina ceramic having a relative dielectric constant of about 10 for the insulating layer, an organic material such as polyimide or epoxy resin is used for a glass epoxy resin base material having a relatively small relative dielectric constant of 3 to 5. A so-called build-up substrate formed by using such a method has come to be used. In such a build-up substrate, a conductor film for internal wiring made of copper (Cu) is formed on an insulating layer by using a thin film forming technique such as a plating method, a vapor deposition method, or a sputtering method, and the photolithography method or the like. By forming a fine pattern wiring conductor layer by etching method, by alternately laminating this insulating layer and wiring conductor layer in multiple layers,
2. Description of the Related Art Fabrication of a multi-layer wiring board having high density, high functionality, and capable of high-speed operation of a semiconductor element has been performed. In addition, as the operation speed of the semiconductor device is increased, the operation speed of the semiconductor device cannot be increased due to the mismatch of the characteristic impedance of the through conductor formed in the multilayer wiring board. Has also occurred. To cope with such a problem, Japanese Patent Application Laid-Open
A wiring structure as disclosed in JP-A-77808 has been proposed. This is one in which an opening having an area equal to or larger than the cross-sectional area of the through conductor is formed in the wiring conductor layer formed to face the through conductor. According to this method, it is possible to reduce the occurrence of characteristic impedance mismatch in the through conductor portion, and thus it is possible to suppress signal reflection. In addition, the number of signals has been increasing with the increase in the operating speed of semiconductor devices. In response to such a demand, the build-up substrate can form a fine pattern of wiring conductors, and thus has been used as a wiring substrate on which a semiconductor element operating at high speed is mounted. [0010] However, in the build-up board, since a connection land extending from a through conductor formed in a core board in the build-up board is large, Japanese Patent Laid-Open No. 2000-77808 is disclosed. In the structure as disclosed in the above, the size of the opening in the wiring conductor layer becomes large, the conductor region between the openings decreases, and the resistance value and the inductance value of the wiring conductor layer increase. Is more likely to occur. Here, simultaneous switching noise is a phenomenon in which noise occurs in a power supply or ground circuit during signal switching, and the simultaneous switching noise tends to increase as the inductance value of the power supply or ground wiring conductor layer increases. Can be seen. Therefore, in order to prevent simultaneous switching noise from increasing, it is necessary to reduce the size of the opening of the wiring conductor layer. In this case, electromagnetic coupling between the connection land and the wiring conductor layer is required. There is a problem that the characteristic impedance is reduced due to the increase, and the characteristic impedance is mismatched. As described above, the characteristic impedance mismatch locally generated in the connection land hardly causes a problem when the frequency of the propagating signal is not so high. In particular, the frequency of the signal is 1 GHz or more. When a semiconductor element that operates at a high speed is mounted, signal reflection becomes large and the problem of ringing noise occurs remarkably.
Here, the ringing noise is a phenomenon in which a signal propagated due to different characteristic impedances of a signal wiring, a through conductor, and a connection land is generated, and the reflected noise appears in the signal. SUMMARY OF THE INVENTION The present invention has been completed to solve the above problems, and an object of the present invention is to prevent simultaneous switching noise from increasing, to reduce characteristic impedance mismatching at connection lands, and to generate ringing noise. An object of the present invention is to provide a multilayer wiring board suitable for an electronic circuit board or the like on which electronic components such as semiconductor elements operating at a high speed can be reduced. According to the present invention, there is provided a multilayer wiring board comprising: an insulating base; a through conductor penetrating the insulating base;
A core substrate including a connection land extending from the through conductor on the surface of the insulating base, a multilayer wiring portion including a plurality of insulating layers and a plurality of wiring conductor layers stacked on the surface of the core substrate, An insulating covering layer formed on the surface of the multilayer wiring portion, wherein an opening having an area equal to or larger than the area of the connection land is formed in a region of the wiring conductor layer facing the connection land, and An opening having an area equal to or less than the area of the opening and having an area equal to or greater than the cross-sectional area of the through conductor is formed in a region of the coating layer facing the opening. According to the multilayer wiring board of the present invention, an opening having an area smaller than the area of the connection land and larger than the cross-sectional area of the through conductor is formed in the area of the wiring conductor layer facing the connection land. Since the relative dielectric constant between the connection land and the wiring conductor layer is substantially reduced, the electromagnetic coupling between the connection land and the wiring conductor layer can be reduced. As a result, it is possible to prevent the characteristic impedance of the connection land from lowering, so that it is possible to reduce the occurrence of mismatching of the characteristic impedance of the connection land. Therefore,
Generation of ringing noise can be reduced. Further, since the opening is formed in a region of the insulating coating layer opposite to the opening of the wiring conductor layer, a decrease in characteristic impedance can be prevented even if the area of the opening formed in the wiring conductor layer is reduced. Therefore, the conductor region between the adjacent openings formed in the wiring conductor layer becomes large, so that the resistance value and the inductance value of the wiring conductor layer are reduced, and the occurrence of simultaneous switching noise can be reduced. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a multilayer wiring board according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view of an essential part showing an example of an embodiment of a multilayer wiring board of the present invention, and FIG. 2 is a plan view of an essential part showing an example of a wiring conductor layer in the multilayer wiring board of the present invention. . In these figures, reference numeral 1 denotes a multilayer wiring board. Reference numeral 2 denotes an insulating base, and the insulating base 2 includes a through conductor 3
Are formed, and connection lands 4 extending from the through conductors 3 are formed on the surface of the insulating base 2, and these constitute a core substrate 5. The inside of the through conductor 3 is filled with an insulating material or a conductive material 6, a plurality of insulating layers 7 and a plurality of wiring conductor layers 8 and 9 are formed on the surface of the core substrate 5. Signal wiring through
11 is electrically connected. These plurality of insulating layers 7,
A multilayer wiring portion is formed on the surface of the core substrate 5 by the plurality of wiring conductor layers 8 and 9, the via conductor 10 and the signal wiring 11, and the outermost wiring conductor layer 9 is protected on the surface from oxidation by air. An insulating coating layer 12 is formed. The wiring conductor layers 8 and 9 are formed as wide area patterns for ground wiring or power supply wiring.
The connection land 4 is formed so as to face the wiring conductor layer 9 having a wide area pattern. Here, it is desirable that the connection land 4 be designed so that its characteristic impedance becomes, for example, 50Ω by electromagnetic coupling with the wiring conductor layer 9. When the characteristic impedance of the connection land 4 is different from the characteristic impedance of the through conductor 3 or the via conductor 10,
A mismatch in characteristic impedance causes reflection noise to occur. In the multilayer wiring board of the present invention, as shown in FIG. 1, an opening 13 having an area equal to or larger than the area of the connection land 4 is formed in a region of the wiring conductor layer 9 facing the connection land 4. As a result, electromagnetic coupling between the connection land 4 and the wiring conductor layer 9 can be reduced, so that mismatching of the characteristic impedance in the connection land 4 can be prevented. The area of the opening 13 of the wiring conductor layer 9 is
It is desirable to be as small as possible. In particular, when the openings 13 are adjacent to each other, the area is set so that the adjacent openings 13 are not connected to each other and the conductor region of the wiring conductor layer 9 between the adjacent openings 13 can be formed large. It is desirable. FIG. 4 shows a conventional multilayer wiring board.
This will be described in detail with reference to FIG. FIG. 4 is a sectional view of a main part showing an example of a conventional multilayer wiring board, and FIG. 5 is a plan view of a main part showing an example of a wiring conductor layer in the conventional multilayer wiring board. In these figures, reference numeral 51 denotes a multilayer wiring board. Reference numeral 52 denotes an insulating base, and the insulating base 52 includes a through conductor 53.
Are formed, and connection lands 54 extending from the through conductors 53 are formed on the surface of the insulating base 52, and these constitute a core substrate 55. The inside of the through conductor 53 is filled with an insulating material or a conductive material 56, a plurality of insulating layers 57 and a plurality of wiring conductor layers 58 and 59 are formed on the surface of the core substrate 55, and a via land 60 is formed on the connection land 54. Signal wiring through 61
Are electrically connected. A multilayer wiring portion is formed on the surface of the core substrate 55 by the plurality of insulating layers 57, the plurality of wiring conductor layers 58 and 59, the via conductor 60, and the signal wiring 61,
On its surface, an insulating coating layer 62 for protecting the outermost wiring conductor layer 59 from oxidation by air is formed. The wiring conductor layers 58 and 59 are formed as wide area patterns for ground wiring or power supply wiring.
The connection land 54 is formed so as to face the wiring conductor layer 59 having the wide area pattern. As shown in FIG. 4, a conventional multilayer wiring board 51
In, the connection lands 54 are covered with the insulating layer 57 and also with the insulating covering layer 62. This allows
An insulating material having a high relative dielectric constant is interposed between and around the connection land 54 and the wiring conductor layer 59, and as a result, the electromagnetic coupling between the connection land 54 and the wiring conductor layer 59 is increased, and the connection is made. The characteristic impedance of the land 54 decreases. On the other hand, as a method of improving the reduction of the characteristic impedance of the connection land 54, there is a method of increasing the size of the opening 63 formed in the wiring conductor layer 59. However, as shown in FIG. 5, when the size of the opening 63 of the wiring conductor layer 59 is increased when the connection lands 54 are formed adjacent to each other, the conductor area of the wiring conductor layer 59 between the connection lands 54 is increased. 64 is reduced, the resistance value and the inductance value of the wiring conductor layer 59 are increased, and as a result, simultaneous switching noise is likely to occur. Here, simultaneous switching noise will be described. The power supply required for the switching operation of the semiconductor element is supplied through the wiring conductor layer of the multilayer wiring board. At this time, an inductance value exists in the wiring conductor layer. This inductance has a function of obstructing power supply to the semiconductor element. In particular, when a plurality of semiconductor elements are simultaneously switched, a power supply voltage supplied to the semiconductor elements fluctuates, and noise is generated in a power supply circuit or a ground circuit. These problems become a problem particularly in a multilayer wiring board on which a semiconductor element operating at a high speed of 1 GHz or more is mounted. On the other hand, in the multilayer wiring board 1 of the present invention, as shown in FIG.
An opening 14 having an area equal to or less than the area of the opening 13 of the wiring conductor layer 9 and equal to or greater than the cross-sectional area of the through conductor 3 is formed in a region opposed to the opening 13. Since the opening 14 formed in the insulating coating layer 12 is filled with air, the ratio of the insulating material interposed between and around the connection land 4 and the wiring conductor layer 9 is larger than that of the conventional multilayer wiring board 51. Since the dielectric constant is reduced and the electromagnetic coupling between the connection land 4 and the wiring conductor layer 9 is reduced, even when the size of the opening 13 formed in the wiring conductor layer 9 is smaller than the conventional multilayer wiring board 51, The characteristic impedance of the connection land 4 can be appropriately set to a desired value. FIG. 3 shows another embodiment of the multilayer wiring board of the present invention in a plan view similar to that of FIG. 2, and according to the structure of the multilayer wiring board of the present invention, Since the substantial relative dielectric constant between the wiring conductor layer 21 and the wiring conductor layer 22 can be reduced, the area of the opening 23 formed in the wiring conductor layer 22 is reduced even when the connection lands 21 are formed adjacent to each other. However, the characteristic impedance can be prevented from lowering. Thereby, the resistance value and the inductance value of the wiring conductor layer 22 decrease, and as a result, simultaneous switching noise can be reduced. In the multilayer wiring board of the present invention, a similar wiring structure may be further laminated in multiple layers to form a multilayer wiring board. Further, a multilayer wiring board may be constructed by attaching a chip resistor, a thin film resistor, a coil inductor, a cross inductor, a chip capacitor or an electrolytic capacitor, or the like. The shapes of the insulating substrate 2 and the respective insulating layers 7 in plan view may be square, rectangular, diamond, hexagonal or octagonal. The multi-layer wiring board of the present invention includes a package for storing electronic parts such as a package for storing semiconductor elements, a substrate for mounting electronic parts, a so-called multi-chip module or multi-chip on which a large number of semiconductor elements are mounted. Used as a package or motherboard. In the multilayer wiring board of the present invention, each insulating layer 7 is made of, for example, polyimide, epoxy resin, fluororesin,
Aluminum oxide sintered body, aluminum nitride sintered body, silicon carbide based sintered body, silicon nitride based sintered body using an organic insulating material such as polynorbornene or benzocyclobutene or by a ceramic green sheet laminating method. Insulating material using inorganic insulating material such as ceramic, mullite sintered body or glass ceramic sintered body, or combining inorganic insulating powder such as ceramic powder with thermosetting resin such as epoxy resin Formed using an electrically insulating material. These insulating layers 7 are manufactured as follows. For example, in the case of an epoxy resin, the upper surface of an insulating layer made of a glass epoxy resin or the like formed by impregnating a ceramic or glass fiber woven cloth of a ceramic or a glass fiber with an epoxy resin is generally used. An insulating layer 7 made of an organic resin such as an epoxy resin formed by applying a resin precursor by a coating technique such as a spin coating method or a curtain coating method and subjecting the same to a thermosetting treatment, and copper by an electroless plating method. It is manufactured by alternately stacking thin film wiring conductor layers 8 and 9 formed by adopting a thin film forming technique such as a vapor deposition method and a photolithography technique and heating and curing at a temperature of about 170 ° C. The via conductor 10 is also formed simultaneously with the wiring conductors 8 and 9 in the same manner. In the case where the insulating layer 7 is formed by applying and curing the above-described epoxy resin, for example, the through-hole for forming the via conductor 10 of the insulating layer 7 is formed by excimer laser after the curing. And a method of irradiating a laser such as a CO ₂ gas laser. When the insulating layer 7 is formed of a photosensitive material, a through hole for forming the via conductor 10 is formed at the same time as the insulating layer 7. For example, when the insulating layer 7 is formed of photosensitive polyimide, a photosensitive polyimide resin is applied by a spin coating method or the like, and a portion to be a through hole is irradiated with ultraviolet light or the like while masking a portion to be a through hole. After the other resin is cured, the resin can be formed by removing the resin in the portion to be the through hole. When the insulating layer 7 is made of, for example, an aluminum oxide sintered body, first, an appropriate organic binder, a solvent or the like is added to a raw material powder such as aluminum oxide, silicon oxide, calcium oxide or magnesium oxide. A ceramic green sheet is obtained by mixing to form a slurry and forming the sheet into a sheet by employing a conventionally known doctor blade method. An appropriate punching process is performed on the ceramic green sheet to form a through hole in which the via conductor 10 is formed. Then, a metal paste to be the via conductor 10 is printed and embedded in the through-hole, and each wiring conductor layer 8 is formed.
And 9 are printed and coated in a predetermined pattern, laminated one above the other, and finally fired at a temperature of about 1600 ° C. in a reducing atmosphere. The thickness of the insulating layer 7 is appropriately set according to the characteristics of the material to be used so as to satisfy conditions such as mechanical strength and electrical characteristics corresponding to required specifications. The insulating coating layer 12 is formed by the same method using the same material as that for forming the insulating layer 7. At that time, the insulating layer 7 formed in the outermost layer in a predetermined shape can be used as the insulating coating layer 12. Further, after forming the insulating layer 7, the insulating coating layer 12 may be formed using a material different from the insulating layer 7, for example, by applying and curing an epoxy resin solder resist in a predetermined shape, or It may be formed by applying a solder resist made of a photosensitive epoxy resin on the entire surface, irradiating it with ultraviolet light or the like through a mask having a predetermined shape, and curing it, and removing unnecessary uncured portions. When the insulating layer 7 is made of, for example, a sintered body of aluminum oxide, the outermost layer of the ceramic green sheet on which a predetermined pattern is formed by the metal paste in the method of forming the insulating layer 7 described above. By forming the insulating coating layer 12 in a predetermined pattern on the ceramic green sheet to be formed using a paste having the same components as the ceramic green sheet, the insulating coating layer 12 is formed simultaneously with the insulating layer 7. When the insulating coating layer 12 is formed as described above, the opening of the insulating coating layer 12 is formed simultaneously with the formation of the insulating coating layer 12.
14 is also formed. The wiring conductor layers 8 and 9 are made of, for example, tungsten (W), molybdenum (Mo), molybdenum manganese (Mo-Mn), copper (Cu), silver (Ag) or silver palladium (Ag-Pd). Or metal powder such as copper (Cu), silver (Ag), nickel (N
i), a thin film of a metal material such as chromium (Cr), titanium (Ti), gold (Au), niobium (Nb), or an alloy thereof may be used. Specifically, for example, in the case of forming a thin film of a metal material, after forming a metal film by a sputtering method, a vacuum evaporation method or a plating method, it can be formed into a predetermined wiring pattern by a photolithography method. On the other hand, when the metal powder of W is formed by metallization, a metal paste obtained by adding and mixing an appropriate organic binder, a solvent and the like to the W powder is printed in a predetermined pattern on a ceramic green sheet serving as the insulating layer 7. It can be formed by coating and firing this together with the laminate of ceramic green sheets. When the wiring conductor layer 9 is formed as described above, the opening of the wiring conductor layer 9 is formed simultaneously with the formation of the wiring conductor layer 9.
13 is also formed. It should be noted that the present invention is not limited to the above-described embodiment, and that various changes may be made without departing from the spirit of the present invention. According to the multilayer wiring board of the present invention,
A core substrate including a through conductor penetrating the insulating base, and a connection land extending from the through conductor on the surface of the insulating base; a plurality of insulating layers and a plurality of insulating layers stacked on the surface of the core substrate; A multi-layer wiring portion composed of a wiring conductor layer,
An insulating covering layer formed on the surface of the multilayer wiring portion, wherein an opening having an area equal to or larger than the area of the connection land is formed in a region of the wiring conductor layer facing the connection land, and An opening having an area not larger than the area of the opening and having an area equal to or larger than a cross-sectional area of the through conductor is formed in a region of the coating layer opposed to the opening; Since an opening having an area equal to or larger than the area of the connection land is formed in a region of the layer opposite to the connection land, electromagnetic coupling between the connection land and the wiring conductor layer is reduced, and the wiring conductor layer of the insulating coating layer is formed. In the region opposed to the opening of the wiring conductor layer, the opening having an area not larger than the area of the opening of the wiring conductor layer and having an area equal to or larger than the cross-sectional area of the through conductor is formed. Low relative permittivity Because, it is possible to reduce the connection lands of the electromagnetic coupling between the wiring conductor layer. As a result, it is possible to prevent the characteristic impedance of the connection land from lowering, so that it is possible to reduce the occurrence of mismatching of the characteristic impedance of the connection land. Therefore, occurrence of ringing noise can be reduced. Further, since the opening is formed in a region of the insulating coating layer opposite to the opening of the wiring conductor layer, a decrease in the characteristic impedance can be prevented even if the area of the opening formed in the wiring conductor layer is reduced. Therefore, the conductor region between the adjacent openings formed in the wiring conductor layer becomes large, so that the resistance value and the inductance value of the wiring conductor layer are reduced, and the occurrence of simultaneous switching noise can be reduced. As a result, according to the multilayer wiring board of the present invention, simultaneous switching noise is prevented from increasing, and mismatching of characteristic impedance at connection lands is reduced.
It is possible to provide a multilayer wiring board suitable for an electronic circuit board or the like on which electronic components such as a semiconductor element operating at a high speed can be mounted and which can reduce the occurrence of ringing noise.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a principal part showing an example of an embodiment of a multilayer wiring board of the present invention. FIG. 2 is a main part plan view showing an example of a wiring conductor layer in the multilayer wiring board of the present invention. FIG. 3 is a main part plan view showing another example of the wiring conductor layer in the multilayer wiring board of the present invention. FIG. 4 is a sectional view of a main part showing an example of a conventional multilayer wiring board. FIG. 5 is a plan view of a main part showing an example of a wiring conductor layer in a conventional multilayer wiring board. [Description of Signs] 1: Multilayer wiring board 2: Insulating base 3: Through conductor 4, 21: Connection land 5: Core substrate 7: Insulating layers 8, 9: Wiring conductor layer 12: Insulating coating layer 13: (Wiring conductor layer Opening 14): Opening (of insulating coating)

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Claims (1)

1. A core substrate comprising: an insulating base; a through conductor penetrating the insulating base; and a connection land extending from the through conductor on a surface of the insulating base; A multilayer wiring portion including a plurality of insulating layers and a plurality of wiring conductor layers laminated on the surface of the core substrate, and an insulating coating layer formed on the surface of the multilayer wiring portion; An opening having an area equal to or greater than the area of the connection land is formed in a region facing the land, and the area of the insulating covering layer facing the opening is equal to or less than the area of the opening, and A multilayer wiring board, wherein an opening having an area not less than a cross-sectional area is formed.