JP2011029534A - Multilayer wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer wiring board preventing adjacent solder joints from contacting with each other without increasing a manufacturing cost even when connection pads are arranged in a high density. <P>SOLUTION: The multilayer wiring board includes an insulating substrate 10 formed by laminating a first glass ceramic insulating layer and a second glass ceramic insulating layer, a plurality of connection pads 3 provided on a principal plane of the insulating substrate, and through conductors provided in the insulating substrate 10 and electrically connected to the connection pads 3. Grooves 7 are formed in the principal plane of the insulating substrate along each periphery of the plurality of connection pads 3, sides of the connection pads 3 and inner wall surfaces 71 of the grooves 7 are continuously arranged when crossly viewed, and the inner wall surfaces 71 of the grooves 7 are formed with a burn surface. <P>COPYRIGHT: (C)2011,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, an insulating substrate is made of an alumina-based sintered body as a multilayer wiring board applied to a semiconductor element storage package for mounting a semiconductor element such as an IC or LSI or a hybrid integrated circuit device on which various electronic components are mounted. Many things have been used.

  However, in recent years, a multilayer wiring board having a low-resistance wiring layer, specifically, a multilayer wiring having a wiring layer mainly composed of a low-resistance conductor such as Cu, Ag, or Au that melts at about 1050 ° C. A substrate is required, and a glass ceramic sintered body capable of being sintered at a low temperature of 1050 ° C. or lower is used as an insulating base.

  Here, the multilayer wiring board having the glass ceramic sintered body as the insulating base contracts by about 40 to 50% by firing, and the direction parallel to the main surface of the multilayer wiring board (XY direction) is one direction. The average shrinkage is about 15 to 20%. At this time, the shrinkage rate in the X-Y direction varies about 1% at the maximum, and the variation in the shrinkage rate leads to the positional variation of the wiring layer, which deteriorates the dimensional accuracy of the wiring layer. 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.

  On the other hand, as a method for improving the dimensional accuracy of the multilayer wiring board, the two types of glass ceramic green sheets having different firing shrinkage start temperatures are laminated and fired, thereby suppressing shrinkage in the XY direction. A method of contracting in the stacking direction (Z direction) has been proposed (see Patent Document 1).

  According to this method, when the first glass ceramic green sheet starts firing shrinkage, the first glass ceramic green sheet is restrained by the second glass ceramic green sheet that has not started firing shrinkage. When the glass ceramic green sheet 2 starts firing shrinkage, the first glass ceramic insulating layer that has already finished firing (sintered) (the state after sintering of the first glass ceramic green sheet) As a result, the shrinkage in the XY direction due to firing is suppressed, and the position variation of the wiring layer is suppressed.

  On the other hand, on the main surface of the multilayer wiring board (insulating base), when mounting a surface mount component such as a semiconductor element, a connection pad electrically connected to the connection terminal of the surface mount component via a solder joint is provided. A plurality are provided.

  Here, the connection pads provided on the main surface of the insulating base and the connection terminals of the surface mount component are joined by melting the solder bumps by solder reflow, but the connection terminals and the connection pads are provided with high density. Then, there is a problem that the melted solder spreads and adjacent solder joints may come into contact with each other.

  As a method for solving this problem, a method has been proposed in which a solder resist is formed on the main surface of an insulating substrate and a groove is formed in the solder resist (see Patent Document 2).

JP 2001-97767 A JP 2004-47637 A

  However, in order to form the groove on the main surface of the multilayer wiring board (insulating base) as described above, additional processing for that purpose is required, and the manufacturing cost increases.

  In order to solve the above-described problems, the present invention provides a multilayer wiring board in which contact between adjacent solder joints is suppressed even when connection pads are provided at a high density without increasing manufacturing costs. The purpose is to provide.

  The present invention relates to an insulating substrate formed by laminating a first glass ceramic insulating layer and a second glass ceramic insulating layer having a firing shrinkage start temperature higher than the firing shrinkage end temperature of the first glass ceramic insulating layer, A multilayer wiring board including a plurality of connection pads provided on a main surface of the insulating base and a through conductor provided in the insulating base and electrically connected to the connection pad, wherein the insulating base Grooves are formed along the respective peripheral edges of the plurality of connection pads on the main surface of the plurality of connection pads, and the side surfaces of the connection pads and the inner wall surfaces of the grooves are continuous when viewed in cross section. The inner wall surface is a burnt skin surface.

  According to the present invention, the groove is formed along the peripheral edge of each of the plurality of connection pads on the main surface of the insulating base, and the side surface of the connection pad and the inner wall surface of the groove are continuous when viewed in cross section. In addition, since the inner wall surface of the groove is a burnt surface, it is possible to suppress the spread of solder during solder bonding (reflow). Therefore, even when the connection pads are provided at a high density, it is possible to realize a multilayer wiring board in which contact between adjacent solder joints is suppressed.

It is a schematic sectional drawing which shows the state which mounted the surface mounting components on the multilayer wiring board of this invention. It is explanatory drawing of the connection pad and groove | channel shown in FIG. FIG. 2 is a partially enlarged plan view of the multilayer wiring board shown in FIG. 1.

  An embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the multilayer wiring board according to the present invention is formed by laminating first glass ceramic insulating layers 1a, 1b, 1c, 1d and second glass ceramic insulating layers 2a, 2b, 2c, 2d, 2e. An insulating base 10, a plurality of connection pads 3 provided on the main surface of the insulating base 10, and a through conductor 4 provided in the insulating base 10 and electrically connected to the connection pad 3.

  The first glass ceramic insulating layers 1a, 1b, 1c, 1d and the second glass ceramic insulating layers 2a, 2b, 2c, 2d, 2e are formed of a glass ceramic sintered body, whereby copper, silver, It can be formed by simultaneous firing with the connection pads 3 and the through conductors 4 made of a low-resistance conductor having a low melting point mainly composed of gold or the like.

  The first glass ceramic insulating layers 1a, 1b, 1c and 1d and the second glass ceramic insulating layers 2a, 2b, 2c, 2d and 2e are alternately laminated. In FIG. 1, the first glass ceramic insulating layer 1a is laminated. 1b, 1c, 1d are four layers, the second glass ceramic insulating layers 2a, 2b, 2c, 2d, 2e are five layers, and the second glass ceramic insulating layers 2a, 2e are arranged in the uppermost layer and the lowermost layer. It becomes the composition.

  The first glass ceramic insulating layers 1a, 1b, 1c, and 1d and the second glass ceramic insulating layers 2a, 2b, 2c, 2d, and 2e have different firing shrinkage start temperatures during firing. Specifically, the firing shrinkage start temperature of the second glass ceramic green sheet for forming the second glass ceramic insulating layers 2a, 2b, 2c, 2d, 2e is the first glass ceramic insulating layers 1a, 1b. The temperature of the first glass ceramic green sheet for forming 1c and 1d is higher than the firing shrinkage end temperature of the first glass ceramic green sheet, and the second glass ceramic green sheet shrinks after the firing shrinkage of the first glass ceramic green sheet. Is supposed to start.

  Thus, when the first glass ceramic green sheet starts firing shrinkage, it is restrained by the second glass ceramic green sheet that has not yet started firing shrinkage, and the second glass ceramic green sheet undergoes firing shrinkage. When starting, since it is restrained by the first glass ceramic insulating layer that has already finished firing shrinkage, shrinkage in the XY direction due to firing is suppressed as a result.

  A plurality of connection pads 3 are provided on the main surface of the insulating substrate 10. The connection pad 3 functions as a mounting portion for a surface-mounted component such as a semiconductor element, and is formed of a low-resistance conductor mainly composed of copper, silver, gold, or the like. Here, when formed at a high density, for example, the diameter of the connection pad 3 is 90 to 250 μm, particularly 90 to 150 μm, and the interval between the adjacent connection pads 3 (distance between the ends) is It is formed to 60 to 250 μm, particularly 60 to 150 μm.

  Further, in the insulating base 10, there are provided through conductors 4 penetrating the first glass ceramic insulating layers 1a, 1b, 1c, 1d and the second glass ceramic insulating layers 2a, 2b, 2c, 2d, 2e, respectively. And electrically connected to the connection pad 3. Similarly to the connection pad 3, the through conductor 4 is also formed of a low resistance conductor having copper, silver, gold, or the like as a main component.

  In addition to the connection pads 3, a surface wiring layer 5 is provided on the main surface of the insulating base 10, and an internal wiring layer 6 is provided inside the insulating base 10. These function as circuit elements such as inductors and capacitors, or wirings for electrically connecting each circuit element, and are formed of a low-resistance conductor mainly composed of copper, silver, gold or the like.

  As shown in FIGS. 2 and 3, grooves 7 are formed along the peripheral edges of the plurality of connection pads 3 on the main surface of the insulating base 10, and the side surfaces of the connection pads 3 are viewed in cross section. And the inner wall surface 71 of the groove 7 are continuous, and the inner wall surface 71 of the groove 7 is a burnt surface.

  The groove 7 is formed by utilizing the difference in shrinkage rate in the XY direction during firing between the connection pad 3 and the second glass ceramic insulating layer 2a disposed in the uppermost layer.

  As described above, since the second glass ceramic green sheet for forming the second glass ceramic insulating layer 2a is restrained by the first glass ceramic insulating layer 1a during firing, shrinkage in the XY direction due to firing. Is suppressed. On the other hand, although the binding force is also applied to a conductive paste for a connection pad, which will be described later, applied on the second glass ceramic green sheet in order to form the connection pad 3, it is usually more X- than the second glass ceramic green sheet. The shrinkage amount in the Y direction increases. Here, as will be described later, the amount of shrinkage in the XY direction of the connection pad conductor paste is further increased by reducing the filling rate of the inorganic component in the connection pad conductor paste, which is smaller than usual. The difference in shrinkage in the XY direction with the glass ceramic insulating layer 2a becomes larger.

  As a result, stress is generated on the main surface of the insulating base 10 (second glass ceramic insulating layer 2a) along the respective peripheral edges of the plurality of connection pads 3, so that each of the plurality of connection pads 3 is provided. A groove 7 is formed along the periphery, and the side surface of the connection pad 3 and the inner wall surface 71 of the groove 7 are continuous when viewed in cross section. Here, the width and depth of the groove 7 are preferably 20 μm or more in terms of the effect of suppressing the spread of solder. The upper limit of the width and depth is about 40 μm.

  The groove 7 formed in this way has an inner wall surface 71 as a burnt surface, and in addition to the effect of making it difficult for the solder to flow due to the formation of a groove having a desired width and depth, It also has the effect of making solder difficult to flow. Moreover, that the inner wall surface 71 of the groove | channel 7 is a burnt skin surface means that it was not formed by additional processes, such as laser irradiation, after baking.

  In the method of mechanically forming grooves on the glass ceramic green sheet before firing using a press or the like, the periphery of each of the plurality of connection pads 3 is caused by misalignment of the mold or printing misalignment of the connection pad conductor paste. It is difficult to form the groove 7 along which the inner wall surface 71 is a burnt surface. That is, a part of the connection pad 3 is applied to the inner wall surface 71 of the groove 7 due to a displacement of the mold or a printing displacement of the connection pad conductor paste, and the mounting reliability is lowered. On the other hand, when the grooves are formed at a distance from the peripheral edges of the plurality of connection pads 3 so that the inner wall surface 71 of the groove 7 does not cover a part of the connection pads 3, The inner wall surface 71 of the groove 7 is not continuous, and it becomes impossible to cope with higher wiring density.

  In the present invention, grooves 7 are formed along the peripheral edges of the plurality of connection pads 3 on the main surface of the insulating base 10, and when viewed in cross section, the side surfaces of the connection pads 3 and the inner wall surfaces 71 of the grooves 7 are formed. The term “continuous” means that the side surface (end surface) of the connection pad 3 does not enter the groove 7 and the inner wall surface 71 of the groove 7 is exposed over the entire circumference.

  In the present invention, the first glass ceramic insulating layers 1a, 1b, 1c, 1d and the second glass ceramic insulating layers 2a, 2b, 2c, 2d, 2e are not laminated alternately, Two or three glass ceramic insulating layers may be laminated continuously. The laminated form of the first glass ceramic insulating layers 1a, 1b, 1c, 1d and the second glass ceramic insulating layers 2a, 2b, 2c, 2d, 2e is not limited to that shown in FIG. The first glass ceramic insulating layer may be arranged in the uppermost layer and the lowermost layer by replacing the glass ceramic insulating layer and the second glass ceramic insulating layer. However, from the viewpoint of the difference in shrinkage between the connection pad 3 and the glass ceramic insulating layer disposed on the uppermost layer, the second glass ceramic insulating layer is preferably disposed on the uppermost layer.

  1 to 3 show a state in which the semiconductor element 8 as a surface mounting component is mounted on the upper surface of the multilayer wiring board. The connection terminals 81 and the connection pads 3 of the semiconductor element 8 are connected to the solder 9. Are joined by.

  Next, the manufacturing method of the multilayer wiring board of this invention is demonstrated.

  First glass ceramic green sheets for forming the first glass ceramic insulating layers 1a, 1b, 1c and 1d are prepared, and the second glass ceramic insulating layers 2a, 2b, 2c, 2d and 2e are formed. A second glass ceramic green sheet is prepared.

  First, glass powder and ceramic filler powder are prepared as raw material powders for producing each glass ceramic green sheet.

As the raw material powders for the first glass ceramic green sheets, 10 to 30 wt% of Si in terms of SiO _2, 1-9 wt% of Al in terms _{of Al} 2 _{O 3,} 5 to 30 mass% of Mg in terms of MgO Ba is 21 to 35% by mass in terms of BaO, B is 10 to 30% by mass in terms of B ₂ O ₃ , Y ₂ O ₃ , CaO, SrO, ZnO, TiO ₂ , Na ₂ O, SnO ₂ , P ₂ O ₅ , at least one selected from the group consisting of ZrO ₂ and Li ₂ O is 40 to 90% by mass of glass powder composed of 0 to 20% by mass, Al ₂ O ₃ , SiO ₂ , MgTiO ₃ , CaZrO ₃ , CaTiO ₃ . ₃ , a material composed of 10-60 mass% ceramic filler powder containing at least one selected from the group consisting of BaTi ₄ O ₉ , SrTiO ₃ , ZrO ₂ , TiO ₂ , AlN and Si ₃ N ₄ Is preferably employed.

  Here, said glass powder is glass from which a crystal | crystallization precipitates by baking processing, and is a glass from which a crystal | crystallization precipitates before baking of a 2nd glass ceramic green sheet.

  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 the amount of firing shrinkage is extremely reduced. If crystals have already precipitated in the first glass ceramic green sheet at a temperature at which the second glass ceramic green sheet starts firing shrinkage, the firing shrinkage in the XY direction of the second glass ceramic green sheet is suppressed. The effect to do becomes high.

  Therefore, by using this glass powder, it is possible to lower the firing shrinkage start temperature of the first glass ceramic green sheet, and further, crystals are formed from the glass before the second glass ceramic green sheet starts firing shrinkage. Precipitation makes it possible to effectively suppress firing shrinkage of the insulating base 10 in the XY direction.

On the other hand, the raw material powder for the second glass-ceramic green sheets, 20 to 60 wt% of Si in terms of SiO _2, 10 to 25 wt% of Al in terms _{of Al} 2 _{O 3,} the Mg in terms of MgO 8-35 wt%, 10 to 20 _wt% of Ba in terms of _{BaO, B 2 O 3, Y 2} O 3, CaO, SrO, selected from _{Na 2 O, SnO 2, P} 2 O 5, ZrO 2 and Li ₂ O groups 30 to 100% by mass of glass powder composed of 0 to 20% by mass and Al ₂ O ₃ , SiO ₂ , MgTiO ₃ , CaZrO ₃ , CaTiO ₃ , BaTi ₄ O ₉ , SrTiO ₃ , ZrO _2. A material composed of 0 to 70% by mass of a ceramic filler powder containing at least one selected from the group consisting of TiO ₂ , AlN, and Si ₃ N ₄ is employed.

  As the glass powder, lithium silicate, quartz, cristobalite, enstatite, cordierite, mullite, anorthite, serdian, spinel, garnite, willemite, dolomite, petalite, diopside and the like by firing treatment Glass that precipitates crystals of the substituted derivative may be used, or amorphous glass that does not precipitate crystals even when subjected to a baking treatment.

  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. To form a first glass ceramic green sheet and a second glass ceramic green sheet having a thickness of 10 to 500 μm.

  Here, the first glass ceramic green sheet and the second glass ceramic green sheet are pressure-bonded, or the first glass ceramic green sheet is formed and then the second glass ceramic green sheet is directly formed on the surface thereof. (The order may be changed) A glass ceramic green sheet composite may be prepared.

  Next, a through hole having a diameter of 60 to 200 μm is formed in the first glass ceramic green sheet and the second glass ceramic green sheet by a laser, a micro drill, punching, or the like.

  Subsequently, a conductor paste for penetrating conductor that fills through holes formed in the first glass ceramic green sheet and the second glass ceramic green sheet is prepared.

  Metal powder and glass powder are prepared as raw material powder.

As the metal powder, copper, silver, and gold are preferable in terms of low resistance. Further, for the purpose of adjusting the sintering start temperature of the metal powder, a metal powder coated with an inorganic oxide such as alumina or silica may be used. Glass powder is added for the purpose of adjusting the sintering behavior, improving the adhesive strength with the glass ceramic green sheet, and reducing the difference in thermal expansion between the through conductor and the glass ceramic insulating layer. Zinc-based glass, lead borosilicate-based glass, and the like can be exemplified, but in particular, they are excellent in co-firing with metal powder at 800 to 1100 ° C., and can improve the adhesive strength with the glass ceramic green sheet. _{, SiO 2 -Al 2 O 3 -BaO} -CaO-B 2 O 3 based glass is preferred.

  In addition to this, the sintering behavior can be adjusted by adding a filler component such as alumina or silica and an organic component such as resin beads.

  Then, the above metal powder and glass powder, an organic binder, an organic solvent, and a dispersant as required are mixed to produce a conductor paste for through conductor, and the through hole is filled with the conductor paste for through conductor by screen printing or the like. In addition, it is preferable that the viscosity of the conductor paste for through conductors is 100 to 350 Pa · s in consideration of the filling property to the through holes.

  Next, a conductor paste for an internal wiring layer is produced. As the raw material powder, only metal powder may be used, and glass powder, filler components, and the like may be added in order to adjust the sintering behavior and improve the adhesive strength with the glass ceramic green sheet. Moreover, it is preferable that the particle size of a metal powder is 5 micrometers or less. Moreover, as a viscosity of the conductor paste for internal wiring layers, 60-100 Pa.s is preferable from a viewpoint of printability, leveling property, and apply | coating thinly. The production method is the same as that of the conductor paste for through conductors.

  Then, the conductor paste for the internal wiring layer is applied to the surfaces of the first glass ceramic green sheet and the second glass ceramic green sheet by screen printing or the like to form a wiring pattern.

  Next, a connection pad conductor paste is prepared. The manufacturing method is the same as that of the conductor paste for the internal wiring layer.

  However, in the connection pad conductor paste, it is important to reduce the filling rate of the inorganic component. Here, the filling rate of the inorganic component in the connection pad conductor paste is an inorganic component such as metal powder, glass powder, inorganic filler, etc. contained in the connection pad conductor paste, an organic binder, an organic solvent, a dispersant, and the like. This refers to the proportion of the volume of the inorganic component in the total volume of the conductor paste for connection pads including the organic component. As a method of reducing the filling rate of the inorganic component, a method of reducing the particle size of the metal powder, glass powder and filler component in the connection pad conductor paste, an organic binder, organic solvent and dispersion in the connection pad conductor paste Examples thereof include a method of increasing the amount of an organic component such as an agent and a method of adding a solid organic component such as resin beads. And as a filling rate of the inorganic component in the conductor paste for connection pads, it is necessary to be 50% or less, and it is especially preferable that it is 45% or less. The viscosity of the connection pad conductor paste is preferably 10 to 50 Pa · s from the viewpoints of printability, leveling properties, and thin application.

The filling rate was determined by filling the pycnometer with the connection pad conductor paste and measuring the mass of the connection pad conductor paste, then adding distilled water to the pycnometer to determine the volume, and the metal powder density of 10.49 g / and cm ^3, the density of the organic component as 1 g / cm ^3, is obtained by calculating the volume fraction of the inorganic component.

  Then, the connection pad conductor paste is applied by screen printing or the like to the surface of the second glass ceramic green sheet disposed in the uppermost layer when laminated, thereby forming a wiring pattern.

  The conductive paste for the surface wiring layer may be the same as the conductive paste for the internal wiring layer, or may be the same as the conductive paste for the connection pad. It is the same as the conductor paste, and is preferably printed simultaneously with the connection pad conductor paste.

  Each glass ceramic green sheet or glass ceramic green sheet composite thus obtained is laminated according to a predetermined lamination order to produce a glass ceramic green sheet laminate.

  For the lamination of glass ceramic green sheets, heat and pressure are applied to the stacked glass ceramic green sheets by thermocompression, and an adhesive composed of organic binder, plasticizer, organic solvent, etc. is applied between the sheets and thermocompression bonded. It is possible to adopt a method to do so.

  Next, the glass ceramic green sheet laminate is fired at 800 to 1000 ° C., particularly 850 to 950 ° C. Prior to firing, if necessary, the glass ceramic green sheet laminate can be heat-treated at 100 to 800 ° C., particularly 400 to 750 ° C. to decompose and remove organic components. At this time, when copper is used as the metal powder in each conductor paste, it is preferably fired in a nitrogen atmosphere from the viewpoint of preventing oxidation.

  In firing, after reaching the firing shrinkage start temperature of the first glass ceramic insulating layer, the temperature may be gradually raised to the maximum temperature, which is higher than the firing shrinkage end temperature of the first glass ceramic green sheet, The glass ceramic green sheet of No. 2 may be temporarily held at a temperature lower than the firing shrinkage start temperature and then raised to the maximum temperature.

  The multilayer wiring board thus fabricated has excellent dimensional accuracy in which the first glass ceramic insulating layer and the second glass ceramic insulating layer are prevented from firing shrinkage in the XY directions, and the grooves are formed. The additional processing for forming is not required, and the contact of the adjacent solder joints obtained by suppressing the manufacturing cost is suppressed.

  Regarding the multilayer wiring board of the present invention, an evaluation board was produced as follows.

First, the 1st glass ceramic green sheet was produced. Specifically, SiO ₂ is 23.8% by mass, B ₂ O ₃ is 17.9% by mass, Al ₂ O ₃ is 8.4% by mass, MgO is 15.4% by mass, and BaO is 26.5% by mass. %, SnO ₂ 1.0 mass%, CaO 4.9 mass%, SrO 0.4 mass%, ZrO ₂ 1.7 mass% glass powder 60 mass%, Al ₂ O ₃ powder 40 A raw material powder consisting of mass% was prepared. Then, using this slurry prepared by adding an acrylic resin as an organic binder, dioctyl phthalate as a plasticizer, and toluene as a solvent to this raw material powder, it is molded by a doctor blade method, and is a first glass ceramic having a thickness of 200 mmSQ and a thickness of 84 μm. A green sheet was produced.

Subsequently, a second glass ceramic green sheet was produced. Specifically, SiO ₂ is 43.3 mass%, B ₂ O ₃ is 7.5 mass%, Al ₂ O ₃ is 12.9 mass%, MgO is 18.0 mass%, and CaO is 1.7 mass%. %, BaO 14.1% by mass, Y ₂ O ₃ 1.0% by weight, SrO 0.5% by mass, ZrO ₂ 1.0% by mass glass powder 60% by mass, Al ₂ O ₃ A raw material powder consisting of 40% by mass of powder was prepared. Then, using this slurry prepared by adding an acrylic resin as an organic binder, dioctyl phthalate as a plasticizer, and toluene as a solvent to this raw material powder, a second glass ceramic having a thickness of 200 mmSQ and a thickness of 84 μm is formed by a doctor blade method. A green sheet was produced.

Next, through holes having a diameter of 100 μm were formed in the obtained first glass ceramic green sheet and second glass ceramic green sheet by punching, and a conductive paste for through conductors was filled in the through holes by screen printing. The through conductor conductor paste of silver powder 100 parts by weight of the average particle size of 5 [mu] _m, a _{SiO 2 -Al 2 O 3 -BaO-} CaO-B 2 O 3 based glass was added 10 parts by weight, also organic An acrylic resin is used as a binder, and a mixed solution of terpineol and dibutyl phthalate (80:20 by mass) is added and kneaded as a solvent.

Subsequently, a conductor paste for an internal wiring layer was produced. Specifically, 0.5 parts by mass of SiO ₂ —Al ₂ O ₃ —BaO—CaO—B ₂ O ₃ glass is added to 100 parts by mass of silver powder having an average particle diameter of 2.5 μm, and organic 2.6 parts by mass of an acrylic resin as a binder and 5.3 parts by mass of a mixed solution of terpineol and dibutyl phthalate (80:20 by mass) as a solvent were added and kneaded.

Subsequently, a connection pad conductor paste and a surface wiring layer conductor paste were prepared. Specifically, silver powder having an average particle diameter of 2.5 μm was prepared, acrylic resin as an organic binder with respect to the silver powder, and a mixed solution of terpineol and dibutyl phthalate (80:20 by weight) as a solvent. Or acrylic resin beads were further added and kneaded. The filling rate shown in Table 1 is the density of the metal powder after filling the pycnometer with the connection pad conductor paste and measuring the mass of the connection pad conductor paste, then adding distilled water to the pycnometer to determine the volume. The volume ratio of the inorganic component was calculated with 10.49 g / cm ³ and the density of the organic component as 1 g / cm ³ .

  Next, when a glass ceramic green sheet laminate described later among the second glass ceramic green sheets is produced, the diameter of the conductive paste for connection pads is baked on the second glass ceramic green sheet disposed in the uppermost layer. Printing was performed by a screen printing method with a pattern such that the distance between the adjacent connection pads 3 (distance between the ends) was 100 μm and 100 μm. The internal wiring layer conductive paste and the surface wiring layer conductive paste were patterned so that it was possible to determine whether or not a short circuit occurred between adjacent connection pads when the semiconductor element was mounted by solder bonding.

  Four first glass ceramic green sheets and five second glass ceramic green sheets thus prepared are prepared, and the second glass ceramic green sheet to which the connection pad conductor paste is applied is the uppermost layer. The first glass ceramic green sheet and the second glass ceramic green sheet are alternately arranged so that an adhesive is uniformly applied between the glass ceramic green sheets, and pressure lamination is performed under conditions of 45 ° C. and 4 MPa. And a glass ceramic green sheet laminate was produced.

Subsequently, the glass ceramic green sheet laminate is cut into a size of 30 mm × 30 mm, and the obtained glass ceramic green sheet laminate is placed on an Al ₂ O ₃ base plate and heated at 400 ° C. in the atmosphere. After the treatment to decompose and remove organic components such as an organic binder, baking was performed at 910 ° C. for 1 hour.

  Next, Ni-Au plating was performed on the connection pads of the obtained substrate to produce an evaluation substrate.

  Thereafter, low melting point solder (Sn: Pb weight ratio = 63: 37) was applied to the connection pads.

  Next, a flip chip type semiconductor element having a size of 5 mm × 5 mm having a connection terminal made of a solder bump on the lower surface is prepared, and solder balls (Sn: Pb = 10: 90) having a diameter of 120 μm are prepared. The semiconductor element was mounted on a connection pad of the evaluation board and then mounted on the evaluation board by heating to 220 ° C.

  And the presence or absence of solder spreading was evaluated about the obtained evaluation board | substrate. Specifically, using a custom digital multimeter, CDM-2000D, a probe was applied to an evaluation pad (surface wiring layer) routed from each connection pad, and the presence or absence of a short circuit was measured. When there was no short circuit, it was judged as good, and when a short circuit occurred, it was judged as bad.

  Further, the evaluation substrate is cut and the cross section is polished, the cross section is observed with an image of a scanning electron microscope SEM (Scanning Electron Microscope) 2000 times, and the width and depth of the groove formed along the periphery of the connection pad. Was measured.

  These results are shown in Table 1.

  Sample No. of the present invention. Nos. 2, 3 and 4 have a low filling rate of the conductive paste for the connection pad and grooves are formed along the periphery of the connection pad, so that it was confirmed that the solder did not spread and no short circuit occurred.

  On the other hand, sample no. No. 1 had a high filling rate of the conductive paste for connection pads, no grooves were formed along the periphery of the connection pads, and the solder spread out, confirming a short circuit.

  Sample No. No. 5 shows a case where a groove is formed around the connection pad using a YAG laser after the evaluation board is fabricated (after firing). There is no spread of solder and no short circuit occurs, but additional processing is required and additional It cost.

DESCRIPTION OF SYMBOLS 10 ... Insulating base | substrate 1a, 1b, 1c, 1d ... 1st glass ceramic insulating layer 2a, 2b, 2c, 2d, 2e ... 2nd glass ceramic insulating layer 3 ... Connection pad 4. ..Penetration conductor 5 ... surface wiring layer 6 ... internal wiring layer 7 ... groove 71 ... inner wall surface 8 ... semiconductor element 81 ... connection pad 9 ... solder

Claims (1)

An insulating substrate formed by laminating a first glass ceramic insulating layer and a second glass ceramic insulating layer having a firing shrinkage start temperature higher than the firing shrinkage end temperature of the first glass ceramic insulating layer; A multilayer wiring board including a plurality of connection pads provided on a main surface of the substrate and a through conductor provided in the insulating base and electrically connected to the connection pads,
Grooves are formed along the respective peripheral edges of the plurality of connection pads on the main surface of the insulating base, and the side surfaces of the connection pads and the inner wall surfaces of the grooves are continuous when viewed in cross section. A multilayer wiring board, wherein the inner wall surface of the groove is a burnt surface.