JP2009032937A - Ceramic multilayer substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic multilayer substrate which is excellent in dimensional accuracy and the mountability of a surface mounting component without largely projecting a via hole conductor from the surface. <P>SOLUTION: First ceramic insulating layers 1a and 1e are sintered at a firing shrinkage end temperature lower than the firing shrinkage start temperature of second ceramic insulating layers 2a and 2d, the thickness of the first ceramic insulating layers 1a and 1e is set to the half of the thickness of the second ceramic insulating layers 1a and 1e or less, and a first via hole conductor 7a formed on the first ceramic insulating layers 1a and 1e and a second via hole conductor 7b formed on the second ceramic insulating layers 2a and 2d are directly connected together. The cross sectional shape of the second via hole conductor 7b is circular in shape having the same diameter over the depth direction, and the center position of one end face of the second via hole conductor and the center position of the other end face are separated from each other by 1/3 of the above diameter or more in the view from a lamination direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ceramic multilayer substrate in which firing shrinkage in a plane direction is suppressed by alternately laminating and firing two types of insulating ceramic green sheets having different shrinkage curves (behavior) in firing.

  Conventionally, in a ceramic multilayer substrate used in the field of mobile communication, etc., high-conductivity gold, silver, copper, aluminum, or a mixture thereof is used as the wiring layer material, and the melting point of the wiring layer material as the insulating layer material Ceramic multilayer substrates using glass ceramics that can be fired at a lower temperature are widely used.

  In this ceramic multilayer substrate, a plurality of wiring layers are electrically connected by via-hole conductors. In manufacturing, a through hole is formed in a ceramic green sheet that becomes an insulating layer after firing, and the through hole is filled with a conductor material that becomes a via-hole conductor after firing, and the ceramic green sheet in which the through hole is filled with a conductor material is formed. A conductor material to be a wiring layer is applied to the main surface. A plurality of ceramic green sheets prepared as described above are laminated and fired to obtain a ceramic multilayer substrate in which wiring layers are connected by via-hole conductors.

  Here, the ceramic multilayer substrate using glass ceramics as the material for the ceramic insulating layer shrinks in volume by about 40 to 50% by sintering from the state of the ceramic green sheet laminate before sintering. At this time, the shrinkage rate in a direction (plane direction) parallel to the main surface of the ceramic multilayer substrate varies about 15 to 20% on average in one direction, and the variation in the shrinkage rate leads to the variation in the position of the wiring layer. The dimensional accuracy of the substrate was poor. The shrinkage referred to here is defined as a value obtained by dividing a value obtained by subtracting a size after sintering from a size before sintering by a size before sintering.

Therefore, as a method for improving the dimensional accuracy of the ceramic multilayer substrate, two or more kinds of ceramic green sheets having different firing shrinkage start temperatures and firing shrinkage end temperatures (in the case of two kinds, the first ceramic insulating layer and the second ceramic sheet after firing are used). A method of suppressing firing shrinkage in the planar direction and shrinking mainly in the vertical direction has been proposed (see, for example, Patent Document 1).
JP 2003-69236 A

  In the method described in Patent Document 1, the firing shrinkage start temperature and firing shrinkage end temperature of the first ceramic green sheet that becomes the first ceramic insulating layer after firing, and the second ceramic insulation layer that becomes the second ceramic insulating layer after firing. Since the firing shrinkage start temperature and firing shrinkage end temperature of the ceramic green sheet are different, the shrinkage in the planar direction is suppressed. For example, when the second ceramic green sheet starts firing shrinkage (sintering) after completion of firing shrinkage (sintering) of the first ceramic green sheet, firing shrinkage ( The sintering of the first ceramic green sheet is suppressed by the second ceramic green sheet that has not yet started firing shrinkage at the time of sintering), and is already fired at the time of firing shrinkage (sintering) of the second ceramic green sheet. The shrinkage in the planar direction of the second ceramic green sheet is suppressed by the first ceramic insulating layer that has finished shrinking (sintered). Therefore, shrinkage in the vertical direction (stacking direction) of the first ceramic green sheet and the second ceramic green sheet is increased.

  However, since the via-hole conductors formed on each ceramic green sheet are the same material, there is no difference in the firing shrinkage start temperature and firing shrinkage end temperature, and the via-hole conductors formed in the inner insulating layer that is in contact with each other are directly connected If they are, they do not suppress contraction in the plane direction. Therefore, if an attempt is made to shrink by the original volume shrinkage, the shrinkage in the vertical direction (stacking direction) of the via-hole conductor is not as great as the shrinkage in the vertical direction (stacking direction) of the ceramic green sheet.

  For this reason, as shown in FIG. 6, the via-hole conductor 50 greatly protrudes from the surface of the ceramic multilayer substrate 40 after firing, which causes a problem that the mountability of the surface-mounted component is deteriorated.

  The present invention has been made in view of such circumstances, and provides a ceramic multilayer substrate with good dimensional accuracy and good mountability of surface-mounted components in which via-hole conductors do not protrude greatly from the surface. Objective.

  The present invention relates to an inner ceramic in which two types of ceramic insulating layers sintered at different firing shrinkage start temperatures and firing shrinkage end temperatures are alternately laminated, and the outermost ceramic insulation layer is in contact with the outermost ceramic insulation layer. Sintered at a firing shrinkage end temperature lower than the firing shrinkage start temperature of the insulating layer, and the thickness of the outermost ceramic insulating layer is 2 of the thickness of the inner ceramic insulating layer in contact with the outermost ceramic insulating layer A first via hole conductor formed in the outermost ceramic insulating layer and a second via hole conductor formed in the inner ceramic insulating layer in contact with the outermost ceramic insulating layer. A directly connected ceramic multilayer substrate, wherein the second via-hole conductor has a circular shape having the same diameter in the cross-sectional shape in the depth direction, and is viewed from the front in the stacking direction. A ceramic multilayer substrate and the center position of the center position and the other end face of the one end surface of the second via hole conductor, characterized in that apart one-third or more of said diameter.

  According to the present invention, the contraction force when the inner ceramic insulating layer in contact with the outermost ceramic insulating layer contracts in the stacking direction acts so as to contract the second via-hole conductor, so that the dimensional accuracy is improved. As a result, a ceramic multilayer substrate with good mountability of the surface mount component in which the via-hole conductor does not protrude greatly from the surface can be obtained. In particular, it is possible to improve the mountability of the surface mount component mounted by flip chip mounting or the like.

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

  FIG. 1 is a cross-sectional view of an embodiment of the ceramic multilayer substrate of the present invention, which is a ceramic multilayer substrate in which two types of insulating layers sintered at different firing shrinkage start temperatures and firing shrinkage end temperatures are alternately laminated. is there. Specifically, as shown in FIG. 1, the first ceramic insulating layers 1a to 1e made of glass ceramics and the second ceramic insulating layers 2a to 2e made of glass ceramics different from the first ceramic insulating layers 1a to 1e are used. 2d are alternately laminated. A surface wiring layer 5a is provided on the surface of the ceramic multilayer substrate, and a via-hole conductor including an internal wiring layer 5b and first via-hole conductor 7a and second via-hole conductor 7b described later is provided inside the ceramic multilayer substrate. It has been.

  The first ceramic insulating layers 1a to 1e and the second ceramic insulating layers 2a to 2d are obtained by sintering ceramic green sheets having different firing shrinkage start temperatures and firing shrinkage end temperatures, respectively. In other words, the second ceramic green after the first ceramic green sheet finishes the firing shrinkage is set so that the firing shrink start temperature of the ceramic green sheet becomes higher than the firing shrink end temperature of the first ceramic green sheet. The sheet is set to start firing shrinkage.

In the selection of the glass ceramic material, the crystallization temperature of the glass contained in the first ceramic green sheet is selected to be lower than the softening point of the glass contained in the second ceramic green sheet. As a method for achieving this, the simplest method is to vary the softening point of the glass by varying the glass composition. In addition, it can be achieved by varying the amount ratio of glass and filler, or adding a nucleating agent such as TiO ₂ , CeO ₂ , SnO as a third additive for changing the firing shrinkage start temperature. Thus, when the second ceramic green sheet starts firing shrinkage, the firing shrinkage of the first ceramic green sheet is finished, and it is possible to suppress the mutual shrinkage in the planar direction.

  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. Moreover, the completion | finish temperature of baking shrinkage here means the temperature when 90% or more of volume shrinkage | contraction with respect to the shrinkage | contraction amount from the state before baking to the state after completion | finish of baking. The volume shrinkage is determined by converting the linear shrinkage of TMA (thermomechanical analysis) into volume shrinkage.

  As the selection of the glass ceramic material, the first ceramic insulating layers 1a to 1e and the second ceramic insulating layers 2a to 2d are 30% by mass or more of crystallized glass, particularly 40 to 90% by mass, and further 50 to 80% by mass. It is preferable from the viewpoint of sinterability. And among the crystallized glass to be contained, the amount of residual glass is 10% by mass or less, particularly 5% by mass or less, and further 2% by mass or less. Desirable from the viewpoint of dielectric loss. The residual glass amount can be determined from the XRD diffraction pattern by Rietveld analysis. The determination of glass can be obtained by a program analysis in which a sample and ZnO (standard sample) are mixed at a predetermined ratio and all crystal phases formed on the sample and a ZnO standard sample are taken into consideration.

Specifically, the first ceramic insulating layers 1a to 1e and the second ceramic insulating layers 2a to 2d are composed of crystallized glass and an inorganic filler, and examples of the crystallized glass include diopside, hardistonite, It is preferable to form at least one crystal among celsian, cordierite, anorsite, garnite, willemite, spinel, mullite, forsterite, and sourite. Of these, diopside, hardestite, celsian, willemite, and forsterite are particularly desirable in terms of dielectric properties, and diopside, celsian, cordierite, and anorthite are desirable in terms of strength. Diopside and celsian are desirable in terms of strength. The inorganic _{filler, Al 2 O 3, SiO 2} , MgTiO 3, CaZrO 3, CaTiO 3, Mg 2 SiO 4, BaTi 4 O 9, ZrTiO 4, SrTiO 3, BaTiO 3, TiO 2, AlN, Si 3 N ₄ can be exemplified. Among these, Al ₂ O ₃ , MgTiO ₃ , CaZrO ₃ , CaTiO ₃ , Mg ₂ SiO ₄ , and BaTi ₄ O ₉ are particularly desirable in terms of dielectric characteristics, and Al ₂ O ₃ , AlN, and Si ₃ N in terms of strength. ₄ is desirable, and Al ₂ O ₃ is more desirable in terms of dielectric properties and strength.

  Thus, by employing glass ceramics made of crystallized glass and an inorganic filler, firing at 1000 ° C. or less is possible. This makes it possible to use a low-resistance conductor mainly composed of Cu, Ag, Al or the like as a conductor material for forming the surface wiring layer 5a, the internal wiring layer 5b, and the via-hole conductors 7a and 7b, thereby realizing high-speed transmission. . The conductive material may contain inorganic components such as other metals, oxides, glass, ceramics, etc. within a range that does not deteriorate the electrical resistance and thermal conductivity with respect to these main components.

The first ceramic insulating layers 1a to 1e and the second ceramic insulating layers 2a to 2d are different in sintering behavior, but not only the difference in sintering behavior but also the relative dielectric constant and bending strength depending on the purpose. Other characteristics such as dielectric loss, thermal conductivity, bulk density, temperature coefficient may be different. For example, the difference in thermal expansion coefficient at 0 to 100 ° C. between the first ceramic insulating layers 1 a to 1 e and the second ceramic insulating layers 2 a to 2 d is 2 × 10 ⁻⁶ / ° C. or less, particularly 1 × 10 ⁻⁶ / It is preferable that it is below ℃. If it is this range, when cooling from the maximum firing temperature, there is less risk of cracks and delamination occurring at the interfaces between the first ceramic insulating layers 1a to 1e and the second ceramic insulating layers 2a to 2d. is there.

  As shown in FIG. 1, the first ceramic insulating layers 1a and 1e are disposed on the outermost side, and the second ceramic insulating layers 2a and 1e are adjacent to the outermost first ceramic insulating layers 1a and 1e. 2d is arranged. The outermost ceramic insulating layer means a ceramic insulating layer that forms a surface, and indicates a ceramic insulating layer that constitutes the upper surface and / or the lower surface of the ceramic multilayer wiring board. Here, the thickness of the outermost first ceramic insulating layers 1a and 1e is set to be half or less of the thickness of the second ceramic insulating layers 2a and 2d. In the first ceramic insulating layers 1a and 1e, only one main surface comes into contact with the second ceramic insulating layers 2a and 2d having different firing shrinkage start temperatures and firing shrinkage end temperatures, and the shrinkage in the plane direction is suppressed. However, the other main surface is not provided with adjacent layers having different firing shrinkage start temperatures and firing shrinkage end temperatures, and the shrinkage in the plane direction is not suppressed. It is considered that the shrinkage suppression effect on the first ceramic insulating layers 1a and 1e is halved. Therefore, since it is necessary to obtain the same shrinkage suppressing effect as that of the other layers, the thickness thereof is set to one half or less.

  Here, a via-hole conductor (first via-hole conductor 7a) formed in the outermost first ceramic insulating layers 1a and 1e, and an inner second in contact with the outermost first ceramic insulating layers 1a and 1e. When the via-hole conductors (second via-hole conductors 7b) formed in the ceramic insulating layers 2a and 2d are directly connected, the protrusion of the via-hole conductors from the surface of the fired ceramic multilayer substrate becomes remarkable. Therefore, it is important to control the vertical contraction of the via-hole conductor (second via-hole conductor 7b) formed in the relatively thick second ceramic insulating layers 2a and 2d. The term “directly connected” means that the end face of the first via-hole conductor 7a is used without using a wiring such as the internal wiring layer 5b between the second ceramic insulating layer 2b and the first ceramic insulating layer 1c. And the end face of the second via-hole conductor 7b are in contact with each other or are formed integrally with no gap.

  The present invention relates to a via-hole conductor (first via-hole conductor 7a) formed in the outermost first ceramic insulating layer 1a and an inner second ceramic insulating layer in contact with the outermost first ceramic insulating layer 1a. The via-hole conductor (second via-hole conductor 7b) formed in the layer 2a is directly connected, and as shown in FIG. 2, the second via-hole conductor 7b has the same cross-sectional shape in the depth direction. And the center position of the one end face 7b1 of the second via-hole conductor and the center position of the other end face 7b2 are separated from each other by one third or more of the diameter. In other words, the second via-hole conductor 7b is inclined, and a line segment connecting the center position of the one end surface 7b1 and the center position of the other end surface 7b2 of the second via-hole conductor 7b viewed from the stacking direction shown in FIG. (Position E) is one third or more of the diameter. The same applies to the outermost first ceramic insulating layer 1e and the inner second ceramic insulating layer 2d in contact with the outermost first ceramic insulating layer 1e.

  FIG. 2 is an explanatory view showing a state in which the center position of the one end face 7b1 of the second via-hole conductor 7b is separated from the center position of the other end face 7b2 when viewed from the stacking direction. A line segment (position shift E) E connecting the center position of the one end surface 7b1 and the center position of the other end surface 7b2 of the second via-hole conductor 7b is separated by a half of the diameter.

  As shown in FIG. 3, which is an enlarged view of the region surrounded by the circle X shown in FIG. 1, when the second via-hole conductor 7b is formed to be inclined, the first ceramic insulating layer is viewed from the stacking direction. A region A in which 1a and the second via-hole conductor 7b overlap and a region B in which the second via-hole conductor 7b and the first ceramic insulating layer 1b overlap, that is, the second via-hole conductor 7b and the second ceramic insulating layer 2a There are regions A and B where.

  Here, the second ceramic green sheet which becomes the second ceramic insulating layer 2a becomes the first ceramic green sheet and the first ceramic insulating layer 1b which become the first ceramic insulating layer 1a when firing shrinkage. Since the first ceramic green sheet is constrained in the planar direction, it contracts greatly in the vertical direction. In this firing process, the second ceramic green sheet in which the conductor material filled in the through holes formed in the second ceramic insulating layer 2a (the second via-hole conductor 7b after firing shrinkage) contracts greatly in the stacking direction. The first ceramic insulation that has a rigidity due to the shrinkage force of the second ceramic insulating layer 2a (which has already finished firing shrinkage and has rigidity). Since the stress sandwiched between the layer 1a and the first ceramic insulating layer 1b acts on the conductor material that becomes the second via-hole conductor 7b after firing in the region A and the region B, the protrusion of the second via-hole conductor 7b Is considered to be suppressed.

Here, when the contraction amount in the stacking direction of the second ceramic insulating layer is C and the contraction amount in the plane direction is D, the inclination is larger than θ _S expressed by the relationship of tan θ _S = D / C. For example, the conductor material filled in the through-hole formed in the second ceramic insulating layer 2a (the second via-hole conductor 7b after completion of the firing shrinkage) is prevented from protruding by the contraction force of the second ceramic insulating layer 2a. In the present invention, the second via-hole conductor 7b has a circular shape with the same diameter in the cross-sectional shape in the depth direction, and one end surface 7b1 of the second via-hole conductor as viewed from the stacking direction. And the center position of the other end face 7b2 are separated by one third or more of the diameter, an inclination sufficiently larger than θ _S is obtained.

  The conductor material for forming the via-hole conductor 7b has a certain viscosity during firing and is a portion that cannot be pressed down by the second ceramic insulating layer when contracted (the second ceramic insulating layer as viewed from above). Even if there is a portion that does not overlap), it follows the contraction behavior of the portion to be pressed (the portion overlapping the second ceramic insulating layer as viewed from above).

  In the present invention, the second via-hole conductor 7b has a circular shape having the same diameter in the cross-sectional shape in the depth direction, and the center position and the other end surface of the one end surface 7b1 of the second via-hole conductor as viewed from the stacking direction. There is no limitation on the other shapes as long as the center position of 7b2 is more than one third of the diameter. For example, not only the shape of the first via-hole conductor 7a shown in FIG. 1 is not inclined, but also the inclination directions of the first via-hole conductor 7a and the second via-hole conductor 7b for each layer as shown in FIG. May be different. According to this structure, the protrusion can be further pressed down. In the figure, the inclination direction is alternately reversed for each layer, but the inclination direction may be changed as if a spiral is formed. This also improves the effect of pressing down the protrusion.

  Further, as shown in FIG. 5, the first via hole conductor 7a may also be inclined, and the first via hole conductor 7a and the second via hole conductor 7b may be formed coaxially. In this case, the end face (the interface between the first ceramic insulating layer 1a and the second ceramic insulating layer 2a, the first ceramic insulating layer) to which the first via hole conductor 7a and the second via hole conductor 7b are connected is connected. The via-hole conductor (via-hole conductor 7c) may be integrated with continuous side surfaces so that there is no step at the interface between 1e and the second ceramic insulating layer 2d. Thereby, peeling between the 1st via-hole conductor 7a and the 2nd via-hole conductor 7b is suppressed, and a manufacturing yield can be improved.

  As described above, glass ceramics has been described as an example of the material for forming the first ceramic insulating layers 1a to 1e and the second ceramic insulating layers 2a to 2d. However, the ceramics are not particularly limited as long as they are ceramics.

  Next, a method for manufacturing the ceramic multilayer substrate will be described.

  A green sheet made of two kinds of inorganic materials in which the thermal characteristics of the glass contained in the glass ceramics have the above relationship is prepared.

As the first ceramic green sheet material comprising a first ceramic insulating layer 1a~1e after firing, 5-30 mass and the SiO ₂ 10 to 30 wt%, and the _Al 2 _{O 3} 1 to 9 wt% of MgO, %, BaO 21-35 mass%, B ₂ O ₃ 10-30 mass%, Y ₂ O ₃ , CaO, SrO, ZnO, TiO ₂ , Na ₂ O, SnO ₂ , P ₂ O ₅ , 40 to 90% by mass of glass composed of 0 to 20% by mass of at least one selected from ZrO ₂ and Li ₂ O, Al ₂ O ₃ , SiO ₂ , MgTiO ₃ , CaZrO ₃ , CaTiO ₃ , BaTi ₄ O ₉ , a material composed of 10 to 60% by mass of a ceramic containing at least one selected from SrTiO ₃ , ZrO ₂ , TiO ₂ , AlN and Si ₃ N ₄ is employed. The

On the other hand, the second ceramic green sheet material comprising a second ceramic insulating layer 2a~2d after sintering, and the SiO ₂ 20 to 60 wt%, and 10 to 25 wt% _Al 2 _{O 3,} the MgO. 8 to 35 wt%, and 10 to 20 wt% of _{BaO, B 2 O 3, Y} 2 O 3, CaO, SrO, Na 2 O, at least one selected from _{SnO 2, P 2 O 5,} ZrO 2 and Li ₂ O 30 to 100% by mass of a glass comprising 0 to 20% by mass of seeds, Al ₂ O ₃ , SiO ₂ , MgTiO ₃ , CaZrO ₃ , CaTiO ₃ , BaTi ₄ O ₉ , SrTiO ₃ , ZrO ₂ , TiO ₂ , A material composed of 0 to 70% by mass of ceramics including at least one selected from AlN and Si ₃ N ₄ is employed.

  The first ceramic green sheet and the second ceramic green sheet are made into a slurry by mixing the above material, a volatile organic binder that easily volatilizes during firing, an organic solvent, and a plasticizer or a dispersant as necessary. Using this slurry, the tape is formed by a lip coat method, a doctor blade method, or the like, and cut into a predetermined size. Note that the first ceramic green sheet and the second ceramic green sheet may be formed by printing.

  Next, through holes having a desired shape are formed in these green sheets by a method such as laser, punching, or etching. At this time, the inclined through-hole is formed by changing the laser irradiation angle or changing the pressing angle of the mold to the green sheet.

  Here, the first ceramic green sheet and the second ceramic green sheet may be individually processed to form a through hole. However, the first ceramic green sheet and the second ceramic green sheet may be individually formed. When processed, because there are problems such as burrs and chipping in the vicinity of the interface between the first ceramic green sheet and the second ceramic green sheet, peeling due to stress concentration, and misalignment during lamination, The first ceramic green sheet and the second ceramic green sheet may be collectively or divided into a laminate in which the first ceramic green sheet and the second ceramic green sheet are integrated in advance by lamination or the like, and the through hole may be formed by laser. In addition, dividing | segmenting and forming a through-hole means forming a through-hole from two steps or both surfaces of a ceramic green sheet.

  Then, the through-hole is filled with a conductor paste. As a conductive paste, an organic binder, an organic solvent, and, if necessary, an organic or inorganic additive added to gold powder, silver powder, copper powder, or aluminum powder, and kneaded with three rolls Is used. For the filling, a screen printing method is used by using a metal mask or an emulsion mesh screen mask perforated at a position corresponding to the via hole conductor formation position. At this time, as a method of extruding the conductor paste through the mask, a method using a plate-like (or sword-like) squeegee made of polyurethane or the like may be used, and the paste is pressed into the through-hole using a paste extrusion-type squeegee head. An injection method may be used. In addition, the conductor paste is overfilled by adjusting the viscosity and printing conditions of the conductor paste so that the filled conductor paste protrudes from the surface of the ceramic green sheet on the through hole. Thereafter, if necessary, the protruding conductor paste is pressed and pushed into the through hole. Further, the surface wiring layer 5a and the internal wiring layer 5b are deposited by a screen printing method of a conductor paste.

  The ceramic green sheets or insulator pastes thus obtained are laminated according to a predetermined lamination order to form a laminated molded body, and then fired.

  The firing may be multi-stage firing that is temporarily held at a temperature between the shrinkage start temperature of the first ceramic green sheet at which firing shrinkage starts on the low temperature side and the crystallization temperature of the glass contained in the first ceramic green sheet. However, simultaneous firing even at a single keep temperature makes it possible to produce a ceramic multilayer substrate in which firing shrinkage in the planar direction is suppressed, firing accuracy in the vertical direction is high, and projections of via-hole conductors are restrained.

First, as the glass ceramic material A forming the first ceramic green sheet to be the first ceramic insulating layer 1a~1e after firing, 23.8 wt% _SiO 2, 8.4 wt% _Al 2 _O 3, 15.4 mass% of MgO, 26.5 wt% of BaO, 17.9 wt% of _B 2 _O 3, 4.9 wt% of CaO, 0.4 wt% of SrO, 1.0 weight percent SnO _{2. A} glass ceramic material composed of 60% by mass of glass composed of 1.7% by mass of ZrO ₂ and 40% by mass of Al ₂ O ₃ was prepared.

Also, a glass ceramic material B for forming the second ceramic green sheet to be the second ceramic insulating layer 2a~2d after firing, of 43.3 wt% _SiO 2, 12.9 wt% _Al 2 _O 3, 18.0 mass% of MgO, 14.1 wt% of BaO, 7.5 wt% of _B 2 _O 3, 1.0 wt% of _Y 2 _O 3, 1.7 wt% of CaO, 0.5 wt A glass-ceramic material composed of 60% by mass of glass composed of% SrO and 1.0% by mass of ZrO ₂ and 40% by mass of Al ₂ O ₃ was prepared.

  An acrylic organic binder, a plasticizer, and an organic solvent are added to these glass ceramic materials A and B to prepare a slurry, which is formed into a sheet by a doctor blade method, and the first ceramic green sheet and the second ceramic green sheet are formed. Produced. At this time, the thickness of the 1st ceramic green sheet was produced so that it might become 6 micrometers and 37 micrometers after baking. The second ceramic green sheet was prepared to have a thickness of 37 μm, 74 μm, and 148 μm.

  Also, a composite ceramic green sheet was prepared by laminating one first ceramic green sheet and one second ceramic green sheet.

  Next, beta quartz, barium borosilicate glass and organic vehicle are added to the silver powder, and these are stirred and then mixed with a three-roll mill until there is no aggregate of silver powder and organic binder. Produced. The organic vehicle was composed of 5 parts by mass of ethyl cellulose as an organic binder and 95 parts by mass of α-terpineol as an organic solvent, and 15 parts by mass of this organic vehicle was added to 100 parts by mass of silver powder.

  Next, in order to form a via-hole conductor in the first ceramic green sheet, the second ceramic green sheet, and the composite ceramic green sheet, a through hole was formed by a laser, and the conductive paste was filled in the through hole. . An on-contact printer equipped with a paste extrusion head was used for filling the conductor paste.

  In addition, when forming a through-hole with a laser, the irradiation angle of the laser was changed, and the inclined through-hole or the columnar through-hole was formed. In Table 1, the sample in which the cross-sectional shape of the via-hole conductor is shown in FIG. 5 is obtained by individually drilling the first ceramic green sheet and the second ceramic green sheet by laser processing. In Table 1, the cross-sectional shape of the via-hole conductor is prepared by previously laminating the first ceramic green sheet and the second ceramic green sheet for the samples shown in FIGS. 1, 3, 4 and 6. The composite ceramic green sheet is perforated by laser processing, and the first ceramic green sheet and the second ceramic green sheet constituting the composite green sheet are perforated collectively.

  Next, the first ceramic green sheet, the second ceramic green sheet, and the composite ceramic green sheet in which the through-holes are filled with the conductive paste are pressed with a flat plate mold, and the first ceramic green sheet and the second ceramic green sheet are pressed. And the composite ceramic green sheet was laminated, and the portion of the conductor paste protruding from the surface of the ceramic green sheet was pushed into the through hole.

  At this time, the first ceramic green sheet is disposed as the outermost ceramic insulating layer, the second ceramic green sheet is disposed as the inner ceramic insulating layer in contact with the outermost ceramic insulating layer, and the first ceramic green sheet is disposed. The first ceramic green sheet, the second ceramic green sheet, and the composite ceramic green sheet were combined so that the sheets and the second ceramic green sheets were alternately arranged. Further, a predetermined number of sheets were laminated so that the thickness of baking was 700 to 800 μm to obtain a laminate. Before lamination, conductor patterns to be a surface wiring layer and an internal wiring layer were formed on the surfaces of the first ceramic green sheet, the second ceramic green sheet, and the composite green sheet by screen printing.

  Then, after aligning these green sheets, they were laminated to produce a laminate, which was subjected to binder removal treatment at 400 ° C. in the atmosphere, and further fired at 900 ° C. in the atmosphere to produce a ceramic multilayer substrate.

  In the fired ceramic multilayer substrate, the unevenness of the surface near the edge of the substrate was measured with a three-dimensional laser displacement meter. The measurement area was 3 mm × 3 mm including the edge line of the substrate end portion of the ceramic multilayer substrate surface. At this time, of the obtained measurement data, the difference between the lowest point and the highest point on the substrate surface other than the ridge line at the edge of the substrate was defined as the protrusion amount (projection height) and measured. The results are shown in Table 1. Table 1 shows the maximum protrusion amount (projection height) as a result of measuring five substrates. At this time, a product having a protrusion height of less than 30 μm was regarded as good mountability.

In addition, before and after firing, measure the length between the predetermined points on the ceramic green sheet laminate and fired divided grooved wiring board, and measure the shrinkage in the surface direction of the divided grooved wiring board. did. In addition, when the shrinkage rate was measured for each sample and the difference between the maximum value and the minimum value of the shrinkage rate of 10 samples was evaluated as shrinkage variation, all the samples of the present invention were excellent at 0.5% or less. It showed the shrinkage variation.

  Sample No. 1 to 16, the shape of the via-hole conductor 7a and the via-hole conductor 7b is the shape shown in FIG. 1, and the cross-sectional diameter and inclination angle of the via-hole conductor 7a and the via-hole conductor 7b, the first ceramic insulating layer thickness and the second As a result, the line segment (position shift E) connecting the center position of one end face and the center position of the other end face of the via-hole conductor 7a and the via-hole conductor 7b as viewed from the stacking direction is changed. It is what I did.

  First, sample No. 1 of the present invention in which the first ceramic insulating layer thickness is 6 μm, the second ceramic insulating layer thickness is 74 μm, and the diameters of the first via hole conductor 7a and the second via hole conductor 7b are 70 μm. 1 to 5, when the inclination angle of the second via-hole conductor 7b is changed to 10 to 50 °, the protrusion height of the via-hole conductor is reduced as the inclination angle is increased, and the second via-hole conductor 7b When the inclination angle is 20 ° or more, the positional deviation E becomes one third or more of the diameter, and the projection height at this time is 25 μm or less, and it was confirmed that the projection height was reduced.

  Sample No. Nos. 6 to 9 are obtained by making the diameter of the cross section of the second via-hole conductor 7b different from 70 μm, but the positional deviation E is the diameter regardless of the change of the diameter of the cross-section of the second via-hole conductor 7b. It has been confirmed that the height of the protrusion is reduced by being more than one third of the above.

  Furthermore, it was confirmed that the positional deviation E became one third or more of the diameter by changing the thickness of the second ceramic insulating layer, and the protrusion height was reduced (Sample Nos. 15 and 16). Conversely, when the positional deviation E was less than one third of the diameter, it was confirmed that the height of the protrusion could not be reduced (Sample Nos. 12 and 13).

  It can be seen that as the ratio of the thickness of the first ceramic insulating layer to the thickness of the second ceramic insulating layer is increased, the maximum value of the protrusion height tends to be surely deteriorated. Therefore, it can be understood that the thickness of the first ceramic insulating layer is not more than one half of the thickness of the second ceramic insulating layer from the viewpoint of suppressing the protrusion of the via-hole conductor in addition to the shrinkage suppressing effect.

  In addition, the sample No. 1 in which the via hole conductor 7a and the via hole conductor 7b have the shapes shown in FIG. Also in 17-20, it confirmed that protrusion height was reduced.

  Sample No. 2 having the shape shown in FIG. In 21 and 22, it was confirmed that the protrusion height could not be reduced.

It is sectional drawing of one Embodiment of the ceramic multilayer substrate of this invention. It is explanatory drawing which shows the state which the center position of the one end surface of the 2nd via-hole conductor and the center position of the other end surface have left | separated seeing from the lamination direction. FIG. 2 is an enlarged view of a region surrounded by a circle X shown in FIG. 1. It is sectional drawing of other embodiment of the ceramic multilayer substrate of this invention. It is sectional drawing of other embodiment of the ceramic multilayer substrate of this invention. It is sectional drawing of the conventional ceramic multilayer substrate.

Explanation of symbols

1a to 1e... 1st ceramic insulating layers 2a to 2d... 2nd ceramic insulating layer 5a... Surface wiring layer 5b... Internal wiring layer 7a.・ Second via hole conductor

Claims (1)

Two types of ceramic insulating layers sintered at different firing shrinkage start temperatures and firing shrinkage end temperatures are alternately stacked, and the inner ceramic insulating layer is in contact with the outermost ceramic insulating layer in contact with the outermost ceramic insulating layer. Sintered at a firing shrinkage end temperature lower than the shrinkage start temperature, and the thickness of the outermost ceramic insulation layer is less than or equal to half the thickness of the inner ceramic insulation layer in contact with the outermost ceramic insulation layer The first via-hole conductor formed on the outermost ceramic insulating layer and the second via-hole conductor formed on the inner ceramic insulating layer in contact with the outermost ceramic insulating layer were directly connected. A ceramic multilayer substrate,
The second via-hole conductor has a circular shape having the same diameter in the cross-sectional shape in the depth direction, and the center position of one end face and the center position of the other end face of the second via-hole conductor are viewed from the stacking direction. A ceramic multilayer substrate characterized by being separated by one third or more of the diameter.

Images