JP2008135579A - Multilayer wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer wiring board which has a high dimensional accuracy and has a high airtightness by suppressing the occurrence of a gap between the wall surface of a through hole formed in an insulation layer and a via hole conductor. <P>SOLUTION: The multilayer wiring board consists of alternately stacked first insulation layers and second insulation layers. The second insulation layers have a burning shrinkage start temperature higher than the burning shrinkage finish temperature of the first insulation layers. The via hole conductors are so formed as to be penetrated through a laminate consisting of one set of first insulation layer and second insulation layer. On the surface of the laminate on the first insulation layer side, lands are so formed as to be connected to the via hole conductors and cover the via hole conductors. Each land 5 consists of an inside restrained portion 51 and an outside conductor portion 52 so formed as to wrap around the inside restrained portion 51. The burning shrinkage start temperature of either the inside restrained portion 51 or the outside conductor portion 52 is higher than the burning shrinkage finish temperature of the other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multilayer wiring board that can be suitably used for a package for housing semiconductor elements, a hybrid integrated circuit device, and the like.

  Conventionally, as a wiring substrate applied to a package for housing a semiconductor element in which semiconductor elements such as IC and LSI, which have been highly integrated, and various electronic parts are mounted, an alumina sintered body is used. Many insulating substrates have been used. In recent years, the resistance of the wiring layer has been required to be reduced, so that the wiring layer mainly composed of a low resistance conductor such as Cu, Ag, or Au that melts at about 1050 ° C. can be simultaneously fired with the insulating substrate. A glass-ceramic sintered body that can be sintered at a low temperature of 1050 ° C. or lower has been used as an insulating substrate.

  A glass-ceramic sintered body is generally obtained by combining glass and a ceramic filler. Among them, by using crystallized glass as a glass, crystals having desired characteristics are precipitated, Since a glass-ceramic sintered body having characteristics can be obtained, research has been conducted intensively in recent years.

  By the way, a wiring board using a glass ceramic sintered body as an insulating substrate is provided with a wiring layer on the surface or inside of the insulating substrate, and via the via-hole conductor filled with through-holes formed in the insulating substrate. Connected structure. Here, in order to prevent a connection failure due to a shift in the application position of the conductor material serving as the wiring layer or a shift in the lamination position in the connection portion between the wiring layer and the via-hole conductor or in the connection portion between the via-hole conductors. A connection auxiliary conductor layer called a land is provided.

  As a specific method for forming the via-hole conductor and the wiring layer, a glass ceramic raw material powder, a slurry prepared by adding a solvent to an organic binder is formed into a sheet shape by a doctor blade method or the like, and a through hole is formed in the obtained green sheet. The via hole conductor is formed by filling the through hole with a conductive paste mainly composed of Cu, Ag, Au or the like. At the same time, a conductive paste mainly composed of Cu, Ag, Au or the like is formed on the green sheet by printing it into a wiring pattern by a screen printing method or the like, or after forming electrolytic copper foil or rolled copper foil into a desired pattern, the green sheet To form a wiring layer. A plurality of green sheets on which via-hole conductors and wiring layers are formed are pressure-laminated and fired at 800 to 1000 ° C. to produce a multilayer wiring board.

  On the other hand, in recent years, as the density of multilayer wiring boards increases, the demand for higher dimensional accuracy has also increased. Improving the substrate dimensional accuracy to cope with this is also an important technique. The multilayer wiring board shrinks in volume by about 40 to 50% by firing. At this time, the variation in shrinkage rate (average of 15 to 20% in one direction) in the direction parallel to the main surface of the multilayer wiring board (XY direction) is the positional variation of the wiring layer, resulting in poor substrate dimensional accuracy. It was. Here, the shrinkage rate is defined as a value obtained by dividing a value obtained by subtracting a dimension after firing from a dimension before firing by a dimension before firing.

  As a method for improving the substrate dimensional accuracy, two types of green sheets having different firing shrinkage start temperatures or firing shrinkage end temperatures are laminated and fired to suppress shrinkage in the XY direction, mainly in the lamination direction (Z (For example, refer to Patent Document 1).

  According to this method, when one of the green sheets starts firing shrinkage, it is restrained by the other green sheet that has not started firing shrinkage, and when the other green sheet starts firing shrinkage, Since it is restrained by one of the green sheets that has finished (sintered), the shrinkage in the XY direction due to firing is suppressed as a result.

  However, a via-hole conductor formed on the same axis that penetrates two different types of insulating layers (green sheets) is usually fired simultaneously with the insulating layer having the lower firing shrinkage temperature, and therefore faces this insulating layer. If the end portion of the via-hole conductor is formed at such a position, the end portion is not suppressed from contracting in the XY direction. In addition, when two or more types of insulating layers having different via-hole conductors pass through a plurality of layers, for example, four layers, the via-hole conductors penetrating at least the inner two layers are not suppressed from contracting in the XY direction. Therefore, the shrinkage in the XY direction of the via-hole conductor is larger than that of the insulating layer in which the shrinkage in the XY direction is suppressed.

  For this reason, a via-hole conductor will peel from the wall surface of the through hole formed in the insulating layer, and a clearance gap will arise between the through-hole wall surface of an insulating layer and a via-hole conductor. Due to the gap, the airtightness of the multilayer wiring board is deteriorated, and there is a problem that the insulating property of the multilayer wiring board is deteriorated when moisture or the like enters.

In order to solve such a problem, a method has been proposed in which different via-hole conductors are used for different insulating layers made of different materials having different firing shrinkage starting temperatures (see, for example, Patent Document 2).
JP-A-10-308584 JP 2001-189555 A

  However, in the method described in Patent Document 2, when the stacking shift occurs, the end portion facing the insulating layer that does not overlap in the Z direction between the via-hole conductors and has the same firing shrinkage start temperature is X−. Since shrinkage is not suppressed in the Y direction, there is a problem that a gap is generated between the through hole wall surface of the insulating layer and the via hole conductor. Furthermore, even when a via-hole conductor is formed on the outermost layer, the outer side of the via-hole conductor is not suppressed in the X-Y direction, so that a gap is generated between the through-hole wall surface of the insulating layer and the via-hole conductor. was there.

  The present invention is proposed as a result of taking such circumstances into consideration, and its object is to achieve high airtightness with high dimensional accuracy and suppressing the formation of a gap between the through-hole wall surface of the insulating layer and the via-hole conductor. It is to provide a high multilayer wiring board.

  In the present invention, the first insulating layer and the second insulating layer having a firing shrinkage start temperature higher than the end temperature of the firing shrinkage of the first insulating layer are alternately stacked, A via-hole conductor is formed so as to penetrate through the laminated body composed of one insulating layer and the second insulating layer, and the via-hole conductor is connected to the via-hole conductor on the surface of the laminated body on the first insulating layer side. A multilayer wiring board in which lands are formed so as to cover, wherein the lands are composed of an inner restraint portion and an outer conductor portion formed so as to enclose the inner restraint portion, and the inner restraint portion and the One of the outer conductor portions has a firing shrinkage start temperature higher than the other firing shrinkage end temperature.

  When the start temperature of the firing shrinkage of either the inner restraint portion or the outer conductor portion is higher than the end temperature of the other firing shrinkage, when the inner restraint portion starts firing shrinkage, the firing shrinkage is still not caused. When the outer conductor portion is restrained by the outer conductor portion that has not been started and the outer conductor portion starts firing shrinkage, it is restrained by the inner restraint portion that has already finished (sintered) firing shrinkage. Further, shrinkage in the XY direction due to firing of the outer conductor portion is suppressed. On the other hand, when the outer conductor portion starts firing shrinkage first and the inner restraint portion fires and shrinks later, for the same reason, shrinkage in the XY direction due to firing of the inner restraint portion and the outer conductor portion is suppressed. Since the shrinkage of the inner restraint portion and the outer conductor portion forming the land in the XY direction is suppressed, the shrinkage of the land is suppressed, and the firing shrinkage of the via-hole conductor immediately below or immediately above the land is also suppressed. As a result, it is possible to obtain a multilayer wiring board having no gap between the through-hole wall surface of the insulating layer and the via-hole conductor.

  Here, in the multilayer wiring board described above, it is preferable that the inner restraint portion is formed in a size that covers the via-hole conductor. Thereby, the effect of suppressing shrinkage in the XY direction can be provided over the entire end face of the via-hole conductor.

  In the multilayer wiring board, it is preferable that the firing shrinkage start temperature of the outer conductor portion is higher than the firing shrinkage end temperature of the inner restraint portion. Since metal powders such as Cu, Ag, and Au, which are the main components of the outer conductor portion, often continue to be sintered to a relatively high temperature, the firing shrinkage time is long, and the end temperature of firing shrinkage of the first insulating layer This is because the firing temperature of the second insulating layer, which is a higher firing shrinkage starting temperature, is close to the firing temperature of the outer conductor portion and the via-hole conductor, so that the manufacturing is easy.

  In the multilayer wiring board, it is preferable that a firing shrinkage start temperature of the inner restraint portion is higher than an end temperature of firing shrinkage of the second insulating layer. When the multilayer wiring board is manufactured by firing at a temperature close to the end temperature of firing shrinkage of the second insulating layer, firing shrinkage of the outer conductor portion is suppressed by preventing the inner restraint portion from firing shrinkage. As a result, the firing shrinkage of the land is suppressed, and the firing shrinkage of the via-hole conductor immediately below or immediately above the land is also suppressed, so that a wiring board having no gap between the through-hole wall surface of the insulating layer and the via-hole conductor can be realized. However, in this case, since the inner restraint portion is not sufficiently densified, it is preferably used other than the outermost land that requires sufficient adhesion strength with the insulating substrate.

  According to the present invention, the land is composed of the inner restraint portion and the outer conductor portion formed so as to enclose the inner restraint portion, and the firing shrinkage start temperature of either the inner restraint portion or the outer conductor portion. Is higher than the end temperature of the other firing shrinkage, the inner restraint portion and the outer conductor portion mutually restrain the firing shrinkage in the XY direction, and as a result, the firing shrinkage of the land in the XY direction is restrained. Yes. When the firing shrinkage in the XY direction of the land is suppressed, the firing shrinkage in the XY direction of the via-hole conductor immediately below or immediately above the land is also suppressed. Accordingly, a multilayer wiring board having high dimensional accuracy and airtightness can be obtained without generating a gap between the through-hole wall surface of the insulating layer and the via-hole conductor.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a partial sectional view showing the structure of the multilayer wiring board of the present invention, FIG. 2 is an enlarged explanatory view of the land shown in FIG. 1, and the multilayer wiring board of the present invention is as shown in FIGS. The first insulating layer and the second insulating layer having a firing shrinkage start temperature higher than the firing shrinkage end temperature of the first insulating layer are alternately laminated, and the set of the first insulating layers And a via-hole conductor 4 is formed so as to penetrate the laminated body made of the second insulating layer, and a land is connected to the via-hole conductor 4 on the surface of the laminated body on the first insulating layer side so as to cover the via-hole conductor 4. In the formed multilayer wiring board, the land 5 includes an inner restraint portion 51 and an outer conductor portion 52 formed so as to wrap around the inner restraint portion 51. The firing temperature of either firing is the other firing It is characterized in that greater than shrinkage of the end temperature.

  The first insulating layer shown in FIG. 1 has seven layers (1a, 1b, 1c, 1d, 1e, 1f, 1g), and the second insulating layer has six layers (2a, 2b, 2c, 2d, 2e, 2f). ) And are alternately stacked.

  Each of the first insulating layer and the second insulating layer is made of already sintered ceramics, and glass ceramics are used as the ceramics. Examples of ceramics include glass ceramics, alumina, mullite, and the like, but glass ceramics are preferable in that low resistance conductors such as gold, silver, and copper can be used. Hereinafter, a case where the first insulating layers 1a, 1b, 1c, 1d, 1e, 1f, and 1g and the second insulating layers 2a, 2b, 2c, 2d, 2e, and 2f are made of glass ceramics will be described.

  The glass ceramics composing the first insulating layers 1a, 1b, 1c, 1d, 1e, 1f, and 1g and the glass ceramics composing the second insulating layers 2a, 2b, 2c, 2d, 2e, and 2f start firing contraction. The temperature is different. Specifically, the glass ceramics constituting the second insulating layers 2a, 2b, 2c, 2d, 2e, and 2f are the glass ceramics constituting the first insulating layers 1a, 1b, 1c, 1d, 1e, 1f, and 1g. The firing shrinkage is started at a temperature higher than the end temperature of the firing shrinkage. Thereby, when the first insulating layer starts firing shrinkage, it is restrained by the second insulating layer that has not started firing shrinkage, and when the second insulating layer starts firing shrinkage, Since it is restrained by the first insulating layer that has finished firing shrinkage, as a result, shrinkage in the XY direction due to firing is suppressed.

  A set of first insulating layer and second insulating layer, specifically, first insulating layer 1a and second insulating layer 2a, first insulating layer 1b and second insulating layer 2b, first Via hole conductors are formed so as to penetrate through the laminated body composed of the first insulating layer 1d and the second insulating layer 2d, and the first insulating layer 1e and the second insulating layer 2e. Usually, a through-hole is made in a composite green sheet that is a laminate after firing, in which one green sheet that becomes the first insulating layer after firing and one green sheet that becomes the second insulating layer after firing. By forming via-hole conductors.

  A land 5 is formed on the surface of the multilayer body so as to be connected to the via-hole conductor 4 and to cover the via-hole conductor. The land 5 can suppress the occurrence of poor connection between the via-hole conductors 3 due to the misalignment.

  The land 5 formed on the surface of the laminated body on the first insulating layer side includes an inner restraint portion 51 and an outer conductor portion 52 formed so as to wrap the inner restraint portion 51 as shown in FIG. It is important that one of the inner restraint portion 51 and the outer conductor portion 52 has a higher firing shrinkage temperature than the other firing shrinkage end temperature.

  The conventional land is made of the same material as the via-hole conductor, and the firing temperature thereof is close to the firing temperature of the second insulating layer and is fired together with the second insulating layer. Therefore, the first land is connected to the via-hole conductor. The land formed on the surface of the layer side suppresses shrinkage in the XY direction between the second insulating layer facing the side not connected to the via-hole conductor or the via-hole conductor further connected to the side. As a result, the via-hole conductor near the land contracted in the radial direction, and a gap might be generated between the through-hole wall surface. However, according to the present invention, the land is composed of the inner restraint portion 51 and the outer conductor portion 52, which suppress the contraction of each other, so that the contraction of the entire land is suppressed. As a result, shrinkage of the via-hole conductor in the XY direction can also be suppressed.

  When the start temperature of the firing shrinkage of either the inner restraint portion 51 or the outer conductor portion 52 is higher than the end temperature of the other firing shrinkage, when the inner restraint portion 51 starts firing shrinkage, When the outer conductor portion 52 is restrained by the outer conductor portion 52 that has not started firing shrinkage and starts firing shrinkage, it is restrained by the inner restraint portion 51 that has already finished (sintered) firing shrinkage. As a result, shrinkage in the XY direction due to firing of the inner restraint portion 51 and the outer conductor portion 52 is suppressed. On the other hand, when the outer conductor portion 52 starts firing shrinkage first and the inner restraint portion 51 fires and shrinks later, the inner restraint portion 51 and the outer conductor portion 52 shrink due to firing in the XY direction for the same reason. It is suppressed. Since the shrinkage in the XY direction of the inner restraint portion 51 and the outer conductor portion 52 forming the land 5 is suppressed, the shrinkage of the land 5 is suppressed, and the firing shrinkage of the via-hole conductor 3 directly below or immediately above the land 5 is also suppressed. It is suppressed. As a result, it is possible to obtain a multilayer wiring board having no gap between the through-hole wall surface of the insulating layer and the via-hole conductor.

  As a material for forming the inner restraint portion 51, for example, glass ceramics is used. Further, the material for forming the outer conductor portion 52 is not limited as long as it is made of a conductor material, but a conductor whose main component is a metal such as Cu, Ag, or Au is preferably used.

  Here, the firing shrinkage start temperature is defined as the temperature at which the volume shrinks by 0.3% when the target material is fired alone. The term “firing shrinkage end temperature” as used herein refers to a temperature at which the shrinkage amount is 90% or more with respect to the shrinkage amount from the state before firing to the state after firing. The volume shrinkage is determined by TMA (thermomechanical analysis) by individually press-molding the inner restraint portion and the outer conductor portion. At this time, each contracts isotropically and is converted from volumetric shrinkage of TMA to volume shrinkage.

  Here, in the multilayer wiring board described above, it is preferable that the inner restraint portion is formed in a size that covers the via-hole conductor. Thereby, the effect of suppressing shrinkage in the XY direction can be provided over the entire end face of the via-hole conductor.

  Moreover, it is preferable that the start temperature of the firing shrinkage of the outer conductor portion 52 is higher than the end temperature of the firing shrinkage of the inner restraint portion 51. Since metal powders such as Cu, Ag, and Au, which are the main components of the outer conductor portion, often continue to be sintered to a relatively high temperature, the firing shrinkage time is long, and the end temperature of firing shrinkage of the first insulating layer This is because the firing temperature of the second insulating layer, which is a higher firing shrinkage starting temperature, is close to the firing temperature of the outer conductor portion and the via-hole conductor, so that the manufacturing is easy. At this time, the firing shrinkage start temperature of the inner restraint portion 51 is preferably 50 ° C. or more lower than the firing shrinkage start temperature of the outer conductor portion 52 from the viewpoint of suppressing shrinkage in the XY direction of the land, and is 100 ° C. or more lower. Particularly preferred.

  Moreover, the start temperature of the firing shrinkage of the inner restraint portion 51 may be higher than the end temperature of the firing shrinkage of the second insulating layer. When the multilayer wiring board is manufactured by firing at a temperature close to the end temperature of firing shrinkage of the second insulating layer, firing shrinkage of the outer conductor portion is suppressed by preventing the inner restraint portion from firing shrinkage. As a result, the firing shrinkage of the land is suppressed, and the firing shrinkage of the via-hole conductor immediately below or immediately above the land is also suppressed, so that a wiring board having no gap between the through-hole wall surface of the insulating layer and the via-hole conductor can be realized. However, in this case, since the inner restraint portion is not sufficiently densified, it is preferably used other than the outermost land that requires sufficient adhesion strength with the insulating substrate.

  Although not mentioned in detail, a wiring layer 3 that mainly functions as a connection pad serving as an electronic component element mounting portion is provided on the surface of the multilayer wiring board, and each circuit element is mainly provided inside the multilayer wiring board. A wiring layer 3 is provided which functions as a circuit element such as a wiring for electrically connecting the two and an inductor / capacitor.

  Next, a method for manufacturing the multilayer wiring board of FIG. 1 will be described as a method for manufacturing the multilayer wiring board of the present invention. First, two types of green sheets each containing a glass ceramic material for forming the first insulating layer and the second insulating layer are prepared.

  Specifically, first, a glass powder and a ceramic filler powder are prepared as raw material powders in order to produce a green sheet.

The glass powder contains at least SiO ₂ and contains at least one of Al ₂ O ₃ , B ₂ O ₃ , ZnO, PbO, alkaline earth metal oxide, and alkali metal oxide. For example, borosilicate glass such as SiO ₂ —B ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system—MO system (where M represents Ca, Sr, Mg, Ba or Zn) , Alkali silicate glass, Ba glass, Pb glass, Bi glass and the like. These glasses can be amorphous glass even when fired, and lithium silicate, quartz, cristobalite, enstatite, cordierite, mullite, ananosite, serdian, spinel, gallium by firing. -Any one of depositing at least one kind of crystals of knight, willemite, dolomite, petalite, diopside and substituted derivatives thereof can be used.

As the glass for the first insulating layer, glass from which crystals are precipitated by baking treatment is preferable. In glass ceramics, when crystals begin to precipitate from glass, the amount of liquid phase that serves as a driving force for sintering of glass ceramics decreases, so that the amount of firing shrinkage is extremely reduced. If precipitation of crystals in the first insulating layer starts at a temperature at which the second insulating layer starts firing shrinkage, the effect of suppressing firing shrinkage in the XY direction of the second insulating layer becomes high. Therefore, the glass used for the first insulating layer is preferably glass from which crystals are deposited. Among them, 1 to 30 wt% of Si in terms of SiO _2, 5 to 25 wt% of Al in terms _{of Al} 2 _{O 3,} 25 to 60 wt% of Mg in terms of MgO, 0 to 10 mass% of Ca in terms of CaO 0-20 wt% of Ba in terms of BaO, 5 to 25 wt% of B in terms _{of B} 2 _{O 3,} 0-10 wt% of P in terms _{of P} 2 _{O 5,} 0 to 10 mass of Sn in terms of SnO ₂ %, include those containing 0-3 wt% of Na in terms of Na ₂ O. By using the glass, the firing shrinkage start temperature of the first insulating layer can be lowered, and further, the crystal is precipitated from the glass before the second insulating layer starts firing shrinkage, whereby the insulating base 1 It becomes possible to effectively suppress firing shrinkage in the XY direction.

As the glass for the second insulating layer, 10 to 24 wt% of Si 25 to 45 mass% in terms of SiO _2, 10 to 25 wt% of Al in terms _{of Al} 2 _{O 3,} the Mg in terms of MgO, A crystalline glass comprising 5 to 20% by mass in terms of B ₂ O ₃ , 5 to 20% by mass in terms of ZnO, and Ca to 0.5 to 4% by mass in terms of CaO is desirable. By using the above glass, a crystal phase with a high thermal expansion coefficient such as garnite (ZnO.Al ₂ O ₃ ) and enstatite (MgO.SiO ₂ ) is precipitated after firing, and the ceramic wiring board can be made high in thermal expansion. become.

As the ceramic filler powder, SiO ₂ such as quartz and cristobalite, Al ₂ O ₃ , ZrO ₂ , cordierite, mullite, forsterite, enstatite, spinel, magnesia and the like are preferably used. Among these, alumina is preferable from the viewpoint of increasing strength and cost, and quartz is preferable from the viewpoint of increasing thermal expansion.

  At this time, it is desirable that the glass ceramic material for the first insulating layer and the second insulating layer is composed of 30 to 100% by mass of glass powder and 0 to 70% by mass of ceramic filler powder.

  A predetermined amount of the above raw material powder is weighed, and further, an organic binder, an organic solvent, and optionally a plasticizer are added to prepare a slurry, which is then formed into a sheet by a known forming method such as a doctor blade method, a rolling method, or a pressing method. A green sheet forming a ceramic wiring board having a thickness of 10 to 500 μm is formed. In some cases, the green sheet forming the first insulating layer and the second insulating layer is pressure-bonded, or the green sheet to be the first insulating layer is molded and then the second insulating layer is directly formed on the surface. It is also possible to form a green sheet to be a green sheet composite (the order may be changed), and to supply this composite as a layer unit to the subsequent processes.

  Then, a through hole having a diameter of 80 to 200 μm for filling the via paste is formed in the green sheet composite by laser, micro drill, punching or the like.

  Subsequently, a via paste is produced. Metal powder and glass powder are prepared as raw material powder. As the metal powder, Cu, Ag, and Au are preferable in terms of low resistance. For the purpose of adjusting the sintering start temperature of the metal powder, a powder obtained by coating the metal powder with an inorganic oxide such as alumina or silica may be used. Examples of the glass powder include borosilicate glass, zinc borosilicate glass, and lead borosilicate glass.

In particular, SiO ₂ —Al ₂ O ₃ —BaO—CaO—B ₂ O ₃ is superior in that it is excellent in co-firing with metal powder at 800 to 1100 ° C. and can improve the adhesive strength with glass ceramic. Based glass is preferred. However, the glass powder is added for the purpose of adjusting the sintering behavior of the via-hole conductor, improving the adhesive strength with the glass ceramic, and reducing the difference in thermal expansion between the via-hole conductor and the glass ceramic.

  In addition to metal powder and glass powder, the sintering behavior can be adjusted by adding filler components such as alumina and silica and organic components such as resin beads. The via paste is prepared by adding the above metal powder, glass powder, organic binder, organic solvent, and, if desired, a dispersant. The viscosity of the via paste is preferably 100 to 350 Pa · s in consideration of the filling property to the through hole.

  Then, the via paste is filled into the through hole. As the filling method, screen printing or the like is used.

  Subsequently, a conductor paste used for pattern printing (wiring layer formation) is produced. The manufacturing method is the same as that of the via paste. Even if it produces only with metal powder, you may add glass powder, a filler component, etc. in order to adjust shrinkage | contraction behavior and to improve adhesive strength with glass ceramic. The viscosity of the conductor paste is preferably 10 to 120 Pa · s, particularly 20 to 80 Pa · s, from the viewpoint of paste printability, paste leveling properties, and thin coating of the paste.

  Moreover, you may use this conductor paste for the outer side conductor part of a land. In order to effectively suppress the shrinkage of the lands in the XY direction, when setting the firing shrinkage start temperature of the inner restraint portion to a temperature lower than that of the outer conductor portion, the conductor paste for the outer conductor portion is used. It is preferable to add glass or the like to shift the firing shrinkage start temperature of the outer conductor portion to the high temperature side.

  In addition, when the firing temperature of the inner restraint portion is set to a temperature higher than that of the outer conductor portion, the metal powder in the conductor paste for the outer conductor portion is reduced, and the outer conductor is not added without adding glass or the like. It is preferable to shift the firing shrinkage start temperature of the part to the low temperature side. In this case, the average particle size of the metal powder is preferably 5 μm or less.

  Then, the conductor paste is applied to the surface of the green sheet using a coating method such as screen printing to form a wiring pattern.

  Subsequently, a glass ceramic paste that becomes an inner restraint portion of the land is produced. As the raw material powder, a main component glass powder and a ceramic filler powder are prepared. Here, it is important that the firing shrinkage start temperature of either the inner restraint portion or the outer conductor portion is higher than the other firing shrinkage end temperature.

  Thus, when the inner restraint portion starts firing shrinkage, it is restrained by the outer conductor portion that has not started firing shrinkage, and when the outer conductor portion starts firing shrinkage, sintering has already started. As a result, contraction in the XY direction due to firing of the inner restraint portion and the outer conductor portion is suppressed.

  In addition, when the outer conductor portion starts firing shrinkage first and the inner restraint portion fires and shrinks later, the shrinkage in the XY direction due to firing of the inner restraint portion and the outer conductor portion is suppressed for the same reason. Since the shrinkage of the inner restraint portion and the outer conductor portion forming the land in the XY direction is suppressed, the shrinkage of the land is suppressed, and the firing shrinkage of the via-hole conductor directly below or immediately above the land is also suppressed. Thereby, it is possible to realize a multilayer wiring board having no gap between the through-hole wall surface of the insulating layer and the via-hole conductor.

  The same glass as the green sheet can be used as the glass, but by using the glass powder used for the first insulating layer, the firing shrinkage start temperature of the inner restraint portion can be changed to the firing shrinkage start temperature of the outer conductor portion. It is possible to reduce the firing shrinkage in the XY direction of the outer conductor portion by precipitating crystals from the glass. Moreover, it is preferable also from the surface of raw material management to use the same kind of glass powder as a 1st insulating layer for the glass ceramic paste for inner side restraint parts.

  A glass ceramic paste is prepared by adding the above raw material powder, an organic binder, an organic solvent, and a dispersant as required. The viscosity of the glass ceramic paste is preferably 10 to 120 Pa · s, particularly 20 to 80 Pa · s, from the viewpoint of paste printability, paste leveling properties, and thin coating of the paste.

  And the said glass ceramic paste is apply | coated to the surface of the outer side conductor part which comprises a land using coating methods, such as screen printing, and an inner restraint part is formed. At this time, as long as conduction is ensured between the upper and lower outer conductor portions of the inner restraint portion, the inner restraint portion may partly protrude from the outer conductor portion, and in particular, the area of the inner restraint portion is the cross section of the via-hole conductor. Is preferably larger than the area of the outer conductor portion and smaller than the area of the outer conductor portion.

  Subsequently, the conductor paste prepared above is applied to the surface of the inner restraint portion of the land portion by using a coating method such as screen printing to form the outer conductor portion.

  The green sheets or green sheet composites thus obtained are laminated according to a predetermined lamination order to form a laminated molded body, and then fired. For the lamination of green sheets, a method of applying heat and pressure to the stacked green sheets and thermocompression bonding, a method of applying an adhesive composed of organic binder, plasticizer, solvent, etc. between the sheets, and thermocompression bonding are adopted. Is possible.

  Prior to firing, if necessary, the green sheet or laminate thereof can be heat-treated at 100 to 800 ° C., particularly 400 to 750 ° C. to decompose and remove organic components in the laminate. Further, it is preferable that the firing is performed at 800 to 1000 ° C., particularly 850 to 950 ° C., from the viewpoint of sufficient sintering and prevention of oversintering. At this time, when copper is used as the metal in the conductor, firing is preferably performed in a nitrogen atmosphere from the viewpoint of preventing copper oxidation.

  In firing, the following firing may be performed to improve the dimensional accuracy. After the temperature rises and reaches the firing shrinkage start temperature of the first insulating layer, the temperature is gradually raised, or the firing shrinkage start temperature, or the firing shrinkage start temperature or more and the firing shrinkage start temperature of the second insulating layer At the lower temperature, the in-furnace temperature is temporarily maintained, and the first insulating layer is maintained until the firing shrinkage of 90% or more of the final firing volume shrinkage proceeds. At this time, the shrinkage in the XY direction is suppressed and the first insulating layer is fired and shrunk in the Z direction by the second insulating layer that is not fired and shrunk at that temperature. Thereafter, after the first insulating layer shrinks 90% or more of the final firing volume shrinkage, the temperature is raised to the shrinkage start temperature of the second insulating layer or more and fired. By this firing, the second insulating layer is baked and shrunk in the Z direction while the firing shrinkage in the XY direction is suppressed by the first insulating layer that has been almost sintered. As a result, it is possible to manufacture a substrate with high dimensional accuracy in which both the first insulating layer and the second insulating layer are suppressed from firing shrinkage in the XY direction and fired and shrunk in the Z direction.

  The glass ceramic wiring board produced in this manner is a glass ceramic excellent in dimensional accuracy that suppresses firing shrinkage in the XY directions by integrally firing insulating layers having different shrinkage behaviors in firing. Since it is a wiring substrate and the via-hole conductor is also prevented from firing shrinkage in the X-Y direction, it becomes an airtight multilayer wiring substrate in which no gap is generated between the through-hole wall surface of the insulating layer and the via-hole conductor.

  An evaluation board for evaluating the presence or absence of a gap between the through-hole wall surface and the via-hole conductor was produced as follows. In this evaluation board, an insulating layer having a width of 30 mm × 30 mm and a thickness of 330 μm is laminated, and a total of 25 via-hole conductors having a diameter of 90 μm are arranged in the center of the board in 5 rows × 5 columns at intervals of 500 μm. Is a land having a diameter of 125 μm. A manufacturing method will be described below.

First, a green sheet to be a first insulating layer was produced. SiO ₂ is 9% by mass, B ₂ O ₃ is 17% by mass, P ₂ O ₅ is 1.7% by mass, Al ₂ O ₃ is 17% by mass, MgO is 44% by mass, BaO is 8% by mass, SnO ₂ Of 1.7% by mass, CaO 0.5% by mass, and NaO 0.1% by mass of glass powder and quartz powder were prepared. These were 85.6% by mass of glass and 14.4% of quartz powder. %, And an organic binder was added to prepare a glass ceramic composition. Using the slurry prepared by adding an acrylic resin as an organic binder, dioctyl phthalate as a plasticizer, and toluene as a solvent to the raw material powder, a green sheet having a thickness of 200 mmSQ and a thickness of 10 μm was formed by a doctor blade method.

Then, the green sheet used as the 2nd insulating layer was produced. SiO ₂ is 35.9 mass%, B ₂ O ₃ is 12 mass%, Al ₂ O ₃ is 6.6 mass%, MgO is 17.5 mass%, CaO is 2.5 mass%, ZnO is 14.4 mass%. A glass powder containing 5% by mass, a quartz powder, and a CaZrO ₃ powder were prepared. These were weighed 58.7% by mass of glass, 36.5% by mass of quartz powder, and 4.8% by mass of CaZrO ₂ powder. A glass ceramic composition was prepared by adding a binder. Using the slurry prepared by adding an acrylic resin as an organic binder, dioctyl phthalate as a plasticizer, and toluene as a solvent to the raw material powder, a green sheet having a thickness of 200 mmSQ and a thickness of 125 μm was formed by a doctor blade method.

  Then, the green sheet for the first insulating layer and the green sheet for the second insulating layer were prepared one by one, and these were thermocompression bonded to produce a composite green sheet. Also, two green sheets for the first insulating layer and one green sheet for the second insulating layer are prepared for the lowermost layer, and the first insulating layer green sheet is sandwiched between the first insulating layer green sheet and the first insulating layer green sheet. The green sheet for insulating layer was heat-pressed.

  Here, the produced composite green sheet was provided with a through hole having a diameter of 90 μm by punching.

Next, a via paste was produced. 18% by mass of SiO ₂ —Al ₂ O ₃ —BaO—CaO—B ₂ O ₃ glass is added to 100% by mass of copper powder, acrylic resin is used as an organic binder, and terpineol and dibutyl phthalate are mixed as a solvent. A solution (80:20 by mass) was added and kneaded to prepare a via paste. The prepared via paste was filled into the through-hole provided earlier by a screen printing method.

Then, the wiring conductor paste used as an outside conductor part was produced. Copper powder and glass powder having a predetermined mixing ratio (conductor a in Table 1 is copper powder: glass = 100: 0, conductor b is copper powder: glass = 100: 2, conductor c is copper powder: glass = 100: 4 And SiO ₂ —Al ₂ O ₃ —BaO—CaO—B ₂ O ₃ glass is used for the glass), acrylic resin is used as the organic binder for the copper powder, and terpineol and dibutyl phthalate are used as the solvent. A mixed solution (80:20 by weight) was added and kneaded to prepare a wiring conductor paste. The obtained wiring conductor paste was printed by a screen printing method. A pattern having a diameter of 125 μm was printed as a land pattern directly on the via-hole conductor.

Subsequently, a glass ceramic paste serving as an inner restraint was produced. A glass powder and a ceramic powder shown in Table 1 are prepared, and a predetermined mixing ratio (glass ceramic A in Table 1 is glass for first insulating layer: quartz = 85.4: 14.6, glass ceramic B is glass) (SiO ₂ 12.9% by mass, B ₂ O ₃ 20.2% by mass, Al ₂ O ₃ 31.0% by mass, MgO 14.0% by mass, BaO 14.6% by mass, ZrO ₂ 1.9% by mass, CeO ₂ 0.4% by mass, SnO ₂ 0.8% by mass, TiO ₂ 4.2% by mass): Quartz = 85.4: 14.6, glass ceramic C is glass (SiO ₂ 42.9% by mass, B ₂ O ₃ 0.6 mass%, Al ₂ O ₃ 5.0 mass%, MgO 18.0 mass%, CaO 26.0 mass%, Cu ₂ O 0.9 mass%): Quartz = 85.4: 14.6, glass Ceramics D is the first insulating layer Glass: quartz = 5.7: 94.3), an acrylic resin as an organic binder, a mixed solution of terpineol and dibutyl phthalate (80:20 by mass) as a solvent, kneaded, and glass ceramic A paste was prepared. The obtained glass ceramic paste was printed by the screen printing method on the surface of the outer conductor part formed earlier with a diameter of 110 μm.

  Subsequently, the wiring conductor paste prepared earlier was printed as a pattern having a diameter of 125 μm on the surface of the inner restraint portion by screen printing.

  A laminate was prepared using the composite green sheet thus obtained. Three composite green sheets and one composite green sheet prepared for the lowermost layer were prepared, an adhesive was uniformly applied between the green sheets, and pressure lamination was performed at 45 ° C. and 4 MPa.

Subsequently, these laminates are placed on an Al ₂ O ₃ base plate and subjected to heat treatment at 700 ° C. in a nitrogen atmosphere in order to decompose and remove organic components such as an organic binder, and then in a nitrogen atmosphere. And calcination at 900 ° C. for 1 hour.

The obtained evaluation substrate was immersed in a fluorescent penetrating flaw detection liquid, held in a desiccator for 2 hours in a vacuumed state until reaching a pressure of 1 × 10 ⁻² Pa, and then washed with tap water. The via-hole conductor portion was polished by about 50 μm from the substrate surface in the substrate stacking direction, and the presence or absence of penetration of the fluorescent penetrating flaw detection liquid into the through hole was evaluated. Evaluation is made by observing the polished substrate with a fluorescence microscope. Samples with through holes where one or more fluorescent parts are recognized in 25 via holes (present in the table) are defective, and samples at 0 locations (none in the table) are It was a good product.

Moreover, about the wiring conductor paste for outer side conductor parts, and the glass-ceramic paste for inner side restraint parts, it removes an organic solvent content by heat-processing, produces a powder, and is 10 mm in diameter and 8 mm in height by pressing at about 98 MPa. A cylindrical green compact was formed. Each compaction start temperature was evaluated by TMA (thermomechanical analysis) in the temperature range of room temperature to 1000 ° C. for this green compact. At this time, the atmosphere was in nitrogen, and the rate of temperature increase was 10 ° C./min. The results are shown in Table 1.

  Sample No. 4, 6, 7, 11, 12, and 13 can suppress mutual contraction because the firing shrinkage start temperature of one of the inner restraint portion and the outer conductor portion is higher than the end temperature of the other firing shrinkage. As a result, no light was emitted from the fluorescent flaw detection liquid, and it was confirmed that no separation occurred between the through-hole wall surface and the via-hole conductor.

  On the other hand, sample no. 1, Sample No. 1 in which the start temperature of the firing shrinkage of either the inner restraint portion or the outer conductor portion is lower than the end temperature of the other firing shrinkage. In 2, 3, 5, 8, 9, and 10, the inner restraint portion could not suppress firing shrinkage of the outer conductor portion, and as a result, separation occurred.

It is a fragmentary sectional view which shows the structure of the wiring board of this invention. FIG. 2 is an enlarged explanatory view of a wiring layer shown in FIG. 1.

Explanation of symbols

1a-1g ... 1st insulating layer 2a-2g ... 2nd insulating layer 3 ... wiring layer 4 ... via-hole conductor 5 ... land 51 ... inner restraint part 52 ... Outer conductor

Claims (4)

The first insulating layer and the second insulating layer having a firing shrinkage start temperature higher than the firing shrinkage end temperature of the first insulating layer are alternately stacked, and the set of the first insulating layers And a via-hole conductor is formed so as to penetrate the multilayer body composed of the second insulating layer, and is connected to the via-hole conductor on the surface of the multilayer body on the first insulating layer side so as to cover the via-hole conductor. A multilayer wiring board formed of
The land is composed of an inner restraint portion and an outer conductor portion formed so as to enclose the inner restraint portion, and the firing shrinkage start temperature of either the inner restraint portion or the outer conductor portion is the other. A multilayer wiring board characterized by being higher than an end temperature of firing shrinkage. The multilayer wiring board according to claim 1, wherein the inner restraint portion is formed to have a size covering the via hole conductor. 3. The multilayer wiring board according to claim 1, wherein a start temperature of firing shrinkage of the outer conductor portion is higher than an end temperature of firing shrinkage of the inner restraint portion. 3. The multilayer wiring board according to claim 1, wherein a start temperature of firing shrinkage of the inner restraint portion is higher than an end temperature of firing shrinkage of the second insulating layer.

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