JP2011176185A - Method of manufacturing multilayer wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a multilayer wiring board with high dimensional accuracy, which prevents the occurrence of voids near a center of a glass ceramic green sheet laminate while suppressing an increase in capacitance between wiring layers, with a thermal expansion coefficient matched to a thermal expansion coefficient of silicon. <P>SOLUTION: A thickness of a first glass ceramic green sheet after burning is set to 1/10-1/3 of a thickness of a second glass ceramic green sheet after burning. One type of high dielectric particles selected among SiC, TiO<SB>2</SB>, ZnO, and Si<SB>3</SB>N<SB>4</SB>is included only in the first glass ceramic green sheet, and the content of the high dielectric particles contained in the first glass ceramic green sheet is set to increase toward a center layer side from upper and lower layer sides of the glass ceramic green sheet laminate in a lamination direction. Such the glass ceramic green sheet laminate is burned by microwave heating. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a multilayer wiring board in which a multilayer wiring board having an insulating substrate made of glass ceramics is fired by microwave heating.

In recent years, with the advent of the advanced information era, information communication technology has been developed rapidly. As a result, the speed and size of semiconductor devices and the like have been increased, and the wiring layer also reduces the signal transmission loss. Therefore, there is a demand for lower resistance and lower dielectric constant of the insulating substrate. Therefore, it can be densified by firing at 1000 ° C. or lower, and can be fired simultaneously with a wiring layer mainly composed of a low-resistance metal such as copper, silver, or gold, and a glass ceramic having a low dielectric constant is used as an insulating layer. Multilayer wiring boards have been proposed.

  In particular, with regard to semiconductor elements mainly composed of silicon, in recent years, miniaturization and high speed have been rapidly progressing. Along with the miniaturization of wiring connecting between transistors in the element, the resistance of the wiring and the dielectric constant of the insulating film are being reduced.

Conventionally, SiO ₂ has been used as an insulating film of a semiconductor element. However, it is known that when the dielectric constant of the insulating film is further reduced, its mechanical characteristics are lowered. In particular, in a porous insulating film capable of obtaining a very low dielectric constant, the mechanical characteristics are significantly reduced.

  Therefore, when mounting a semiconductor element using such an insulating film having a low dielectric constant on a multilayer wiring board (hereinafter referred to as primary mounting), heat treatment necessary for curing an underfill agent (curing process) As the semiconductor element is heated / cooled due to ON / OFF of the semiconductor element, there is a concern that a thermal stress is generated due to a mismatch of thermal expansion coefficients between the semiconductor element and the multilayer wiring board and the semiconductor element is destroyed. Has been. Furthermore, since the thermal stress increases with an increase in the size of the semiconductor element, the risk of the semiconductor element breaking down further increases.

Therefore, in order to reduce the thermal stress related to the primary mounting, the thermal expansion coefficient of the multilayer wiring board can be matched with the thermal expansion coefficient of silicon (2-4 × 10 ⁻⁶ / ° C .: temperature range: 40-400 ° C.). It has been demanded.

  As a multilayer wiring board having low thermal expansion characteristics, for example, it is known that a multilayer wiring board having a low thermal expansion coefficient can be obtained by using a glass ceramic sintered body made of mullite, quartz glass, or borosilicate glass as an insulating material. (See Patent Document 1).

Further, for example, by combining a borosilicate glass composed of SiO ₂ , B ₂ O ₃ , K ₂ O, and Al ₂ O ₃ with alumina, cordierite, and quartz glass, a multilayer having a low thermal expansion coefficient that enables low resistance wiring. It is known that a wiring board can be obtained (see Patent Document 2).

  In addition, since the miniaturization of semiconductor elements mounted on the multilayer wiring board has been promoted, the multilayer wiring board is required to have dimensional accuracy (accuracy of the interval between connection terminals formed on the main surface). In order to increase the dimensional accuracy, a method of manufacturing a multilayer wiring board that suppresses shrinkage in the planar direction during firing has been proposed.

For example, a mixture of glass powder and ceramic filler is added to an organic binder, plasticizer, solvent, etc. to form a slurry, which is the same as the first glass ceramic green sheet formed by a doctor blade or the like. In the first method,
A second glass ceramic green sheet that starts firing shrinkage at a temperature higher than the firing shrinkage end temperature of the glass ceramic green sheet, and through-holes are formed in each glass ceramic green sheet to form a through conductor paste. A glass ceramic green sheet laminate is prepared by coating a conductive paste for wiring layer on one main surface of at least one glass ceramic green sheet and laminating the first glass ceramic green sheet and the second glass ceramic green sheet. And the glass ceramic green sheet laminate is fired at a temperature at which the second glass ceramic green sheet is fired and contracted (see Patent Document 3).

  According to the manufacturing method disclosed in Patent Document 3, when the first glass ceramic green sheet is fired and shrunk, the second glass ceramic green sheet in a state in which the firing shrinkage has not started is used. Shrinkage in the plane direction of the sheet is suppressed. On the other hand, when the second glass ceramic green sheet is baked and shrunk, the first insulating layer (first glass ceramic green sheet in a state in which the baked shrinkage has already been finished) causes the second glass ceramic green sheet in the planar direction to be shrunk. Shrinkage is suppressed. Note that the shrinkage in the stacking direction increases as the shrinkage in the planar direction is suppressed. With the mechanism as described above, it is possible to improve the dimensional accuracy (accuracy of the interval between the connection terminals formed on the main surface) of the multilayer wiring board (the state after firing the glass ceramic green sheet laminate).

  However, when the method for manufacturing a multilayer wiring board disclosed in Patent Document 3 is used, voids are formed after the organic binder contained in the glass ceramic green sheet is burned out when the glass ceramic green sheet laminate is degreased and fired. Such a phenomenon is likely to appear remarkably in the second insulating layer (the state after sintering of the second glass ceramic green sheet) disposed near the center of the glass ceramic green sheet laminate. There was a problem.

  On the other hand, it is known to use microwave heating when manufacturing a ceramic sintered body. Microwave heating generates heat from the inside of a substance by the interaction between the microwave and the substance, and it is important that a substance having a high dielectric constant with excellent microwave absorption exists.

  For example, it has been proposed that a powder having excellent microwave absorptivity such as silicon carbide is mixed with a powder body such as ceramics and then subjected to microwave firing so that firing can be performed in a short time without uneven burning (see Patent Document 4). reference).

Japanese Patent Publication No. 4-58198 JP-A-5-254923 JP 2002-261443 A JP-A-8-277402

  However, since the powder with excellent microwave absorption has a high dielectric constant, the capacitance between the wiring layers increases if the entire insulating substrate of the multilayer wiring board contains powder with excellent microwave absorption uniformly. As a result, there is a problem that the propagation characteristics of the high-frequency signal are deteriorated.

  In addition, some powders having excellent microwave absorption have a high thermal expansion coefficient, and there is a problem that it is difficult to match the thermal expansion coefficient of the multilayer wiring board with the thermal expansion coefficient of silicon.

  Accordingly, the present invention has been made in view of the above circumstances, and suppresses the generation of voids near the center of the glass ceramic green sheet laminate, and suppresses an increase in capacitance between the wiring layers, while reducing the multilayer wiring. It is an object of the present invention to provide a method for manufacturing a multilayer wiring board with high dimensional accuracy in which the thermal expansion coefficient of a substrate is matched with the thermal expansion coefficient of silicon.

The method for producing a multilayer wiring board according to the present invention includes a first glass ceramic green sheet and a second glass ceramic green sheet that starts firing shrinkage at a temperature higher than a firing shrink end temperature of the first glass ceramic green sheet. Forming a composite sheet by laminating the first glass ceramic green sheet and the second glass ceramic green sheet, and forming a through hole in the composite sheet to form a through conductor A step of applying a wiring layer conductor paste to one main surface of the composite sheet and a plurality of the composite sheets that have been filled with the through conductor paste and applied with the wiring layer conductor paste And producing the glass ceramic green sheet laminate, and the glass ceramic green And a step of firing the sheet laminate, wherein the thickness of the first glass ceramic green sheet after firing is 1 / th of the thickness of the second glass ceramic green sheet after firing. The thickness of the first glass ceramic green sheet and the second glass ceramic green sheet is set so as to be 10 to 1/3, and SiC, TiO ₂ , ZnO and only the first glass ceramic green sheet The first glass ceramic green sheet containing one kind of high dielectric constant particles selected from the group of Si ₃ N ₄ and from the upper and lower layers in the stacking direction of the glass ceramic green sheet laminate toward the center layer The ceramic green sheet laminate having an increased content of the high dielectric constant particles contained in Is fired by microwave heating.

  In the method for manufacturing a multilayer wiring board, the second glass ceramic green sheet in the vicinity of the center in the stacking direction of the glass ceramic green sheet laminate is sandwiched between the first glass ceramic green sheets having the same thickness. It is desirable.

  According to the present invention, the occurrence of voids near the center of the glass ceramic green sheet laminate is suppressed, and the increase in the capacitance between the wiring layers is suppressed, while the thermal expansion coefficient of the multilayer wiring board is reduced to the thermal capacity of silicon. A multilayer wiring board with high dimensional accuracy matched to the expansion coefficient can be easily obtained.

It is explanatory drawing of one Embodiment of the manufacturing method of the multilayer wiring board of this invention. (A) is the plane schematic diagram which saw through the microwave baking furnace used for the manufacturing method of the multilayer wiring board of this invention from the upper surface side, (b) is a cross-sectional schematic diagram of the microwave baking furnace. .

  An embodiment of a method for producing a multilayer wiring board according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a glass ceramic green sheet laminate formed by the method for producing a multilayer wiring board of the present invention. In this embodiment, first, firing shrinkage is performed at a temperature higher than the firing shrinkage end temperature of the first glass ceramic green sheets 11, 12, 13, 14 and the first glass ceramic green sheets 11, 12, 13, 14. The second glass ceramic green sheets 21, 22, 23 to be started are produced.

  The first glass ceramic green sheets 11, 12, 13, 14 and the second glass ceramic green sheets 21, 22, 23 can be fired and shrunk at a relatively low temperature of about 800 to 1000 ° C. The raw material powder prepared at a ratio of 30 to 100% by mass of powder and 0 to 70% by mass of ceramic filler is the main component.

The glass powder contains SiO ₂ and contains at least one of Al ₂ O ₃ , B ₂ O ₃ , SnO, PbO, alkaline earth metal oxide, and alkali metal oxide, SiO ₂ —B ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —MO system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system—MO system (However, M represents Ca, Sr, Mg, Ba, or Zn) and the like, borosilicate glass, alkali silicate glass, Ba-based glass, Pb-based glass, Bi-based glass, and the like can be given. Then, after firing, at least one crystal of lithium silicate, quartz, cristobalite, enstatite, cordierite, mullite, annosite, serdian, spinel, garnite, willemite, dolomite, petalite, diopside and its substituted derivatives A crystalline glass in which types are precipitated is preferred.

  Here, the softening point of the glass powder contained in the second glass ceramic green sheets 21, 22, 23 is higher than the crystallization point of the glass contained in the first glass ceramic green sheets 11, 12, 13, 14. By adjusting so that the firing shrinkage start temperature of the second glass ceramic green sheets 21, 22, 23 is higher than the firing shrinkage end temperature of the first glass ceramic green sheets 11, 12, 13, 14 Can do. Note that the firing shrinkage start temperature here refers to the temperature at which volume shrinkage of 0.5% occurs when the target material is fired alone. The term “firing shrinkage end temperature” refers to a temperature at which volume shrinkage of 90% or more is achieved with respect to the amount of shrinkage from the state before firing to the state after finish of firing. Volume shrinkage is determined by converting from linear shrinkage of TMA (thermomechanical analysis) to volume shrinkage.

Specifically, as the glass powder used for the first glass ceramic green sheets 11, 12, 13, and 14, for example, Si is converted into SiO ₂ in order to start firing shrinkage at low temperature and to precipitate a large amount of crystals. 1-30 mass%, Al is 5-25 mass% in terms of Al ₂ O ₃ , Mg is 25-60 mass% in terms of MgO, Ca is 0-10 mass% in terms of CaO, and Ba is 0-20 in terms of BaO. Mass%, B is 5 to 25 mass% in terms of B ₂ O ₃ , P is 0 to 10 mass% in terms of P ₂ O ₅ , Sn is 0 to 10 mass% in terms of SnO ₂ , and Na is in terms of Na ₂ O What contains 0-3 mass% is mentioned.

Further, as the glass powder used for the second glass ceramic green sheets 21, 22, and 23, the second glass ceramic green sheet 21 after the firing shrinkage of the first glass ceramic green sheets 11, 12, 13, and 14 is completed. as 22 and 23 to start the firing shrinkage, for example 30 to 55 wt% of Si in terms of SiO _2, 15 to 40 wt% of Al in terms _{of Al} 2 _{O 3,} 3 to 25 wt% of Mg in terms of MgO And Zn containing 2 to 15% by mass in terms of ZnO and B containing 2 to 15% by mass in terms of B ₂ O ₃ .

  As the glass powder, non-crystalline glass that does not precipitate crystals after firing may be used due to the blending with the ceramic filler.

As the ceramic filler, SiO ₂ such as quartz and cristobalite, Al ₂ O ₃ , ZrO ₂ , cordierite, mullite, forsterite, enstatite, spinel, magnesia and the like are used. Of these, alumina is preferable in terms of increasing strength, reducing costs, and cordierite and mullite are preferable in terms of reducing thermal expansion.

Here, it is important that the first glass ceramic green sheets 11, 12, 13, and 14 contain high dielectric constant particles having a high relative dielectric constant (εr) in addition to the glass powder and the ceramic filler. . Specifically, only the first glass ceramic green sheets 11, 12, 13, and 14 contain one kind of high dielectric constant particles selected from the group of SiC, TiO ₂ , ZnO, and Si ₃ N ₄ .

The dielectric constant (εr) of the high dielectric constant particles is preferably 7 or more, and SiC (εr = 9 to 12), TiO ₂ (εr = 80 to 180), MgO (εr = 9 to 12), ZnO ( One selected from εr = 8 to 10) and Si ₃ N ₄ (εr = 7 to 9) is selected.

Note that high dielectric constant particles such as ZrO ₂ (εr = 20 to 30), MgO (εr = 9 to 12), and Cr ₂ O ₃ (εr = 10 to 14) have a thermal expansion coefficient of silicon (2 to 2). 4 ppm / ° C .: 40-400 ° C.), it is unsuitable for matching the thermal expansion coefficient of the multilayer wiring board to the thermal expansion coefficient of silicon (2-4 ppm / ° C .: 40-400 ° C.). That is, it is effective to contain one kind of high dielectric constant particles selected from the group of SiC, TiO ₂ , ZnO and Si ₃ N ₄ which are particles having a high dielectric constant and relatively low thermal expansion.

  The high dielectric constant particles are preferably added in a proportion of 3 to 20% by mass with respect to 30 to 90% by mass of the glass powder and 5 to 60% by mass of the ceramic filler. A calorific value sufficient to sinter the ceramic green sheet laminate can be obtained, and an increase in the dielectric constant can be suppressed within a range in which the delay of the high frequency signal can be tolerated. The amount of the high dielectric constant particles added varies depending on the arrangement of the first glass ceramic green sheets 11, 12, 13, and 14 in the glass ceramic green sheet laminate 5 as will be described later. Increases the content of the high dielectric constant particles contained in the first glass ceramic green sheets 11, 12, 13, and 14 from the upper and lower layers side in the stacking direction of the glass ceramic green sheet laminate 5 toward the center layer side. . For example, in the layer configuration shown in FIG. 1, the first glass ceramic green sheet 11 is 3% by mass, the first glass ceramic green sheet 12 is 5% by mass, the first glass ceramic green sheet 13 is 5% by mass, One glass ceramic green sheet 14 has a content of 3% by mass.

In the present invention, only the first glass ceramic green sheets 11, 12, 13, and 14 contain one kind of high dielectric constant particles selected from the group consisting of SiC, TiO ₂ , ZnO, and Si ₃ N _4. The first glass ceramic green sheets 11, 12, 13, and 14 are preferentially heated by microwave heating, and the second glass ceramic green sheets 21, 22, and 23 are heated by heat transfer therefrom. The whole can be uniformly heated and fired, and a multilayer wiring board with high dimensional accuracy can be obtained.

One kind of high dielectric constant particles selected from the group consisting of SiC, TiO ₂ , ZnO and Si ₃ N ₄ has a thermal expansion coefficient close to that of silicon (2 to 4 ppm / ° C .: 40 to 400 ° C.). Therefore, even if it is contained, the thermal expansion coefficient of the multilayer wiring board can be matched with the thermal expansion coefficient of silicon.

  A predetermined amount of the above-mentioned raw material powder is weighed, and 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. It shape | molds and the 1st glass ceramic green sheets 11, 12, 13, and 14 and the 2nd glass ceramic green sheets 21, 22, and 23 are produced, respectively.

Here, the thickness after firing of the first glass ceramic green sheets 11, 12, 13, 14 is not more than one third of the thickness after firing of the second glass ceramic green sheets 21, 22, 23. The thicknesses of the first glass ceramic green sheets 11, 12, 13, 14 and the second glass ceramic green sheets 21, 22, 23 are set. In this case, it is desirable that the thickness of the first glass ceramic green sheets 11, 12, 13 and 14 is 10 to 70 μm, and the thickness of the second glass ceramic green sheets 21, 22 and 23 is 30 to 210 μm.

  When the thickness of the first glass ceramic green sheets 11, 12, 13, 14 after firing is 1/10 to 1/3 of the thickness of the second glass ceramic green sheets 21, 22, 23 after firing, the wiring Between the layers, a first insulating layer (a state after firing the first glass ceramic green sheets 11, 12, 13, and 14) obtained by firing a composite sheet, which will be described later, and a second insulating layer (second glass) Since the ceramic green sheets 21, 22, and 23 are fired), the combined thickness of the ceramic green sheets 21, 22, and 23 suppresses an increase in the capacitance between the wiring layers, and can suppress the delay of the high-frequency signal. In addition, the shrinkage variation after firing of the multilayer wiring board can be reduced. On the other hand, when the thickness after firing of the first glass ceramic green sheets 11, 12, 13, 14 is smaller than 1/10 of the thickness after firing of the second glass ceramic green sheets 21, 22, 23, The variation in shrinkage after firing of the multilayer wiring board is greater than ± 0.1%, and the thickness of the first glass ceramic green sheets 11, 12, 13, 14 after firing is the second glass ceramic green sheet 21. , 22 and 23 are larger than 1/3 of the thickness after firing, the capacitance between the wiring layers increases, resulting in a multilayer wiring board in which a delay of a high-frequency signal is likely to occur.

  Next, the first glass ceramic green sheet 11 and the second glass ceramic green sheet 21, the first glass ceramic green sheet 12 and the second glass ceramic green sheet 22, the first glass ceramic green sheets 13, 14 and A second glass ceramic green sheet 23 is laminated to produce a composite sheet. For the lamination, a method of applying heat and pressure to thermocompression bonding, a method of applying an adhesive composed of an organic binder, an organic solvent, a plasticizer, or the like between sheets can be employed.

  Next, a through hole is formed in the composite sheet and filled with a through conductor paste to form a raw through conductor 31, and a wiring layer conductor paste is applied to one main surface of the composite sheet to form a wiring body. A pattern 41 is formed.

  Formation of the through hole in the composite sheet is performed by a method such as punching, laser, or etching. The through-conductor paste that fills the through-hole is a mixture of silver powder, copper powder, gold powder, etc. as the main component with an organic binder and an organic solvent. Other components such as other metals, glass, oxides, carbides, and nitrides may be included as long as they do not deteriorate. When filling the through-holes with the through-conductor paste 3, a screen printing method using a metal mask or an emulsion mesh screen mask drilled at a location corresponding to the through-hole is used. At this time, as a method of extruding the through-conductor paste through the mask, a method using a plate-like (or sword-like) squeegee such as a normal polyurethane may be used. A method of pressure injection may be used.

The wiring layer conductor paste is applied to one main surface of the composite sheet by a screen printing method or the like. As the conductor paste for the wiring layer, as in the case of the paste for through conductors, an organic binder and an organic solvent are kneaded with silver powder, copper powder, gold powder, etc. as main components, and if necessary, electrical resistance and Insofar as the thermal conductivity is not deteriorated, inorganic components such as other metals, glass, oxides, carbides and nitrides may be included. The wiring layer conductor paste used here and the through conductor paste filled in the through holes may have different viscosities by means such as different amounts of organic solvent. By making the viscosity lower than that of the paste for through conductors, the thickness can be reduced and an accurate pattern can be formed. On the other hand, by increasing the viscosity of the through conductor paste, it is possible to increase the priority density and prevent the through conductor paste from dripping after filling. Further, the wiring layer conductor paste and the through conductor paste may have different main components and subcomponents such as glass and inorganic filler.

  In addition, after filling the paste for through conductors and applying the conductor paste for wiring layers, the composite sheet is dried at a temperature of 60 to 100 ° C. for about 0.5 to 3 hours.

  In the present invention, the wiring layer conductor is formed on one main surface of the composite sheet formed by laminating the first glass ceramic green sheets 11, 12, 13, 14 and the second glass ceramic green sheets 21, 22, 23. Since the paste is applied, the first glass ceramic green sheets 11, 12, 13, 14 and the second glass ceramic green sheet 21, between the wiring layer conductor paste and the wiring layer conductor paste of different layers, 22 and 23 are interposed. Further, the thickness after firing of the first glass ceramic green sheets 11, 12, 13, 14 is not more than one third of the thickness after firing of the second glass ceramic green sheets 21, 22, 23, The thicknesses of the first glass ceramic green sheets 11, 12, 13, 14 and the second glass ceramic green sheets 21, 22, 23 are set. Thereby, the increase in the electrostatic capacitance between wiring layers can be suppressed. The first glass ceramic green sheet is fired in that the effect of restraining the first glass ceramic green sheets 11, 12, 13, and 14 on the second glass ceramic green sheets 21, 22, 23 in firing is enhanced. It is important that the subsequent thickness is 1/10 to 1/3 of the thickness of the second glass ceramic green sheet after firing. The thickness of the first glass ceramic green sheets 11, 12, 13, 14 after firing relative to the thickness of the second glass ceramic green sheets 21, 22, 23 after firing is less than 1/10, or the first When the glass ceramic green sheets 11, 12, 13, and 14 are not used, the firing shrinkage rate and its variation are increased, resulting in a multilayer wiring board with low dimensional accuracy.

  In the present invention, since the composite sheet is prepared as described above, the conductor paste for the wiring layer is applied to one main surface of the composite sheet. Therefore, the second insulating layer is always disposed between the wiring layers after firing. As a result, an increase in capacitance between the wiring layers can be suppressed.

  Next, the composite sheet in which the through hole of the composite sheet is filled with the through conductor paste and the wiring layer conductor paste is applied to the surface of the raw through conductor 31 and the composite sheet to form the wiring layer conductor pattern 41 is formed. A plurality of laminated glass ceramic green sheet laminates 5 are produced.

  For the lamination, a method in which heat and pressure are applied to the stacked composite sheets by thermocompression bonding, a method in which an adhesive composed of an organic binder, an organic solvent, a plasticizer, or the like is applied between the sheets can be employed.

  In terms of the effect of suppressing the shrinkage in the plane direction, as shown in FIG. 1, the first glass ceramic green sheets 11, 12, 13, and 14 and the second glass ceramic green sheets 21, 22, and 23 are Although a configuration in which the layers are alternately stacked is desirable, for example, the first glass ceramic green sheets 11, 12, 13, and 14 may be stacked so as to overlap continuously.

  Here, the content of the high dielectric constant particles contained in the first glass ceramic green sheets 11, 12, 13, and 14 increases from the upper and lower layers side in the stacking direction of the glass ceramic green sheet laminate 5 toward the center layer side. It is trying to become. Thereby, the temperature inside the glass ceramic green sheet laminated body 5 (near the center) can be intentionally made higher than the surface.

When the vicinity of the surface of the glass ceramic green sheet laminate 5 starts to be sintered in a state where the binder removal has not been completed, a path for the generated unsaturated hydrocarbons to be gasified and discharged outside is secured. It disappears and appears as a void after sintering. When voids increase in the multilayer wiring board, the insulation and strength decrease. On the other hand, the content of the high dielectric constant particles contained in the first glass ceramic green sheets 11, 12, 13, 14 from the upper and lower layers side in the stacking direction of the glass ceramic green sheet laminate 5 toward the center layer side. By increasing the number, the vicinity of the surface of the glass ceramic green sheet laminate 5 does not start sintering first, and generation of voids can be suppressed.

  Further, by sandwiching the second glass ceramic green sheet at the center of the glass ceramic green sheet laminate 5 between the first glass ceramic green sheets having the same thickness vertically, the center of the glass ceramic green sheet laminate at the time of firing A second insulating layer disposed in the vicinity of the center of the glass ceramic green sheet laminate that can make uniform temperature variations in the vicinity and easily generate voids (state after sintering of the second glass ceramic green sheet) The generation of voids can be further suppressed.

  Finally, the ceramic green sheet laminate in which the content of the high dielectric constant particles contained in the first glass ceramic green sheet increases from the upper and lower layers side to the center layer side in the lamination direction of the glass ceramic green sheet laminate. The body 5 is fired by microwave heating. During firing, the glass ceramic green sheet laminate 5 is irradiated with microwaves, so that the organic binder of the glass ceramic green sheet laminate 5 is pyrolyzed, and carbon dioxide due to the reaction of unsaturated hydrocarbons generated by pyrolysis with water vapor. Gasification and sintering are performed. At this time, pyrolysis of the organic binder and gasification of carbon dioxide due to the reaction of the unsaturated hydrocarbon generated by pyrolysis with water vapor occurs in a temperature range of about 100 to 800 ° C., and sintering is performed at a temperature of about 800 to 1000 ° C. Occurs in the temperature range.

  The frequency of the microwave used is preferably 1 to 20 GHz, and particularly preferably 2.45 GHz. If this frequency is less than 1 GHz, the wavelength becomes too long, and the heat generation by the microwave of the glass ceramic green sheet laminate 5 decreases, which is not preferable. On the other hand, when the frequency exceeds 20 GHz, the cost of the microwave oscillator is high and is not suitable for industrial use. In particular, when the microwave frequency is 2.45 GHz, the microwave oscillator can be used industrially stably and is relatively inexpensive.

  At the time of firing, when the first glass ceramic green sheets 11, 12, 13, and 14 are fired and shrunk, the first glass ceramic green sheets 21, 22, and 23 that have not started firing shrinkage are used to form the first glass. Shrinkage of the ceramic green sheets 11, 12, 13, and 14 in the planar direction is suppressed. On the other hand, when the second glass ceramic green sheets 21, 22, and 23 are fired and shrunk, the first insulating layer (the first glass ceramic green sheets 11, 12, 13, and 14 in a state in which the firing shrinkage has already been finished) is used. The shrinkage of the second glass ceramic green sheets 21, 22, and 23 in the planar direction is suppressed. Note that the shrinkage in the stacking direction increases as the shrinkage in the planar direction is suppressed. With the mechanism as described above, it is possible to improve the dimensional accuracy (accuracy of the interval between the connection terminals formed on the main surface) of the multilayer wiring board (the state after firing the glass ceramic green sheet laminate 5).

In addition, as a manufacturing method of a multilayer wiring board, when firing a resistor heating furnace conventionally performed as a nitrogen atmosphere, the heat generated by the resistor heats the nitrogen atmosphere by heat transfer. The entire supplied nitrogen gas cannot be heated uniformly, and the temperature of the nitrogen atmosphere near the resistor tends to increase. Further, since heating by radiant heat is inversely proportional to the distance from the resistor, the firing temperature of the glass ceramic green sheet laminate 5 varies depending on the distance from the resistor. Specifically, when firing a plurality of glass ceramic green sheet laminates 5 at the same time, the temperature of the glass ceramic green sheet laminate 5 placed near the resistor is high,
The temperature of the glass ceramic green sheet laminate 5 placed at a position away from the resistor is lowered, and the state of the binder removal and the sintered state vary from product to product. For example, when the glass ceramic green sheet laminate 5 close to the resistor is about to finish firing shrinkage, the glass ceramic green sheet laminate 5 far from the resistor is still fired and deformed.

  Further, when the glass ceramic green sheet laminate 5 is large, such as a probe card wiring board, temperature variations become prominent inside the glass ceramic green sheet laminate 5, and thus warp, etc. There is a problem that the deformation of.

  On the other hand, the firing using the microwave of the present invention can suppress a decrease in dimensional accuracy due to the deformation of the multilayer wiring board in mass production, and further improve the dimensional accuracy than firing by a resistor heating furnace. be able to.

  In addition, as described above, an increase in the capacitance between the wiring layers can be suppressed, and the thermal expansion coefficient of the multilayer wiring board can be matched with the thermal expansion coefficient of silicon (2-4 ppm / ° C .: 40-400 ° C.). The generation of voids in the second insulating layer (the state after the second glass ceramic green sheet is sintered) disposed near the center of the glass ceramic green sheet laminate 5 can be suppressed.

  Hereinafter, a microwave baking furnace used in the method for producing a multilayer wiring board of the present invention will be described. 2A is a schematic plan view of a microwave baking furnace used in the method for manufacturing a multilayer wiring board of the present invention as seen through from the upper surface side, and FIG. 2B is a cross-sectional view of the microwave baking furnace. It is a schematic diagram. In the microwave baking furnace 10, a casing 63 covered with a heat insulating material 62 is disposed in the internal space of the furnace wall 61. In the internal space of the housing 63, a plurality of shelf boards 64 for placing the glass ceramic green sheet laminate 5 are provided at predetermined intervals in the vertical direction by columns 65. The atmospheric gas is supplied to the internal space of the housing 63 through the atmospheric gas supply nozzle 66, and the exhaust gas is discharged from the internal space of the housing 63 to the outside through the exhaust nozzle 67. The decomposition gas generated by the thermal decomposition of the organic binder constituting the glass ceramic green sheet laminate 5 by the microwave irradiation is exhausted from the exhaust nozzle 67 on the side surface that continuously faces without staying in the housing 63. Discharged as.

  The microwave baking furnace 10 may be a batch furnace equipped with a microwave oscillator and a waveguide, or a large continuous furnace.

  Further, the furnace wall 61 in the microwave firing furnace 10 is made of a metal that does not transmit microwaves, and the microwave introduced into the microwave firing furnace 10 through the waveguide is repeatedly reflected by the furnace wall 61. It has become. The heat insulating material 62 is formed of an alumina fiber or a foamed alumina material having microwave permeability. The casing 63 and the shelf plate 64 are made of ceramics such as silicon carbide and alumina, and have a microwave absorption rate that is equal to or higher than the microwave absorption rate of the glass ceramic green sheet laminate 5. It is preferable to use it because the temperature gradient between the surface and the inside of the glass ceramic green sheet laminate 5 becomes extremely small during microwave irradiation. Further, as the atmosphere gas, it is preferable to use a nitrogen atmosphere which is an inert gas, and an atmosphere gas having a dew point of 40 ° C. or more for the purpose of changing unsaturated hydrocarbons which are thermal decomposition products of the organic binder into carbon dioxide gas. Is preferably used.

As raw material powder of the first glass ceramic green sheet, glass powder and quartz powder (ceramic filler) are mixed so as to have a mass ratio of 82:13, and high dielectric constant particles shown in Table 1 are added thereto to add the whole powder. In this case, 100% by mass was used. For example, the ratio is 82% by mass of glass powder, 13% by mass of quartz powder, and 5% by mass of TiO ₂ powder. The composition of the glass powder, 15 wt% of Si in terms of SiO _2, 10 wt% of Al in terms _{of Al} 2 _{O 3,} 30 wt% of Mg in terms of MgO, 1% by mass of Ca in terms of CaO, BaO converted Ba 15 mass%, B is 20 mass% in terms of B ₂ O ₃ , P is 5 mass% in terms of P ₂ O ₅ , Sn is 3.5 mass% in terms of SnO ₂ , and Na is 0.2 mass in terms of Na ₂ O. The content is 5% by mass.

On the other hand, as the raw material powder of the second glass ceramic green sheet, 70% by mass of glass powder, 5% by mass of cordierite powder, 20% by mass of alumina powder, and 5% by mass of filler powder containing at least CaO are used. It was. The composition of the glass powder, 40 wt% of Si in terms of SiO _2, 20 wt% of Al in terms _{of Al} 2 _{O 3,} 20 wt% of Mg in terms of MgO, 8 wt% of Zn in terms of ZnO, the B _{B 2} This is 12% by mass in terms of O ₃ .

  Then, a slurry is prepared by adding an acrylic binder as an organic binder and toluene as an organic solvent to each raw material powder, and a first glass ceramic green sheet and a second glass are respectively formed on a PET film by a doctor blade method. A ceramic green sheet was prepared. The thicknesses of the first glass ceramic green sheet and the second glass ceramic green sheet were set as shown in Table 1. In addition, both the thickness after baking of the 1st glass ceramic green sheet and the 2nd glass ceramic green sheet became 1/2 of the thickness at the time of baking before baking.

Then, after superposing the first glass ceramic green sheet and the second glass ceramic green sheet, the PET film is peeled off, and the composite sheet is composed of the first glass ceramic green sheet and the second glass ceramic green sheet Was made. Furthermore, after the first glass ceramic green sheet is overlaid, the PET film is peeled off, the first glass ceramic green sheet is arranged outside, and the second glass ceramic green sheet is arranged inside. A composite sheet was prepared.

  Next, through holes were formed in the composite sheet by punching, and the through holes were filled with the through conductor paste, and the wiring layer conductor paste was applied to one main surface by screen printing. Here, as a forming material of the paste for through conductors and the conductor paste for wiring layers, ethyl cellulose as an organic binder and 2-2-4-trimethyl-3-3-pentadiol monoisobutyrate as an organic solvent are added to copper powder This paste was used.

  Next, by combining the composite sheets, the first glass ceramic green sheets and the second glass ceramic green sheets are alternately laminated, and the first glass ceramic green sheets are arranged in the outermost layer. A glass ceramic green sheet laminate having four glass ceramic green sheets and three layers of second glass ceramic green sheets was produced. A dot mark was formed on the surface of the glass ceramic green sheet laminate by screen printing using a wiring conductor paste in advance for evaluation of the dimensional accuracy of the multilayer wiring board.

At this time, the content of the high dielectric constant particles of the first glass ceramic green sheet disposed at the center is the amount shown in Table 1, and the glass ceramic green sheet laminate is directed from the upper and lower surfaces in the stacking direction toward the center. As the content of the high dielectric constant particles increases at the rate shown in Table 1, the sample (sample No. 15) in which the increase amount is negative is centered from the upper and lower surfaces in the stacking direction of the glass ceramic green sheet laminate. The content of high dielectric constant particles was reduced toward the side). For example, when the content of the high dielectric constant particles of the first glass ceramic green sheet disposed on the upper and lower surfaces is 4.8% by mass, the high dielectric constant particles of the first glass ceramic green sheet disposed in the center If the content of is 5% by mass, the increase amount is 0.2% by mass. In addition, when the increase amount is 0% by mass, all the layers have the same content.

  Next, the produced glass ceramic green sheet laminate is placed on a shelf plate made of silicon carbide in a case made of silicon carbide that self-heats by microwaves, and nitrogen is supplied into the case while supplying 2.45 GHz. While continuously irradiating the above microwaves to remove organic components, the substrate was baked to 900 ° C. to obtain multilayer wiring boards (Sample Nos. 1 to 9).

  As a comparative example, a multilayer wiring board (sample No. 10) using a firing method using a resistor without containing high dielectric constant particles was prepared, and high dielectric constant particles were not increased without increasing the high dielectric constant particles. The multilayer wiring board (sample Nos. 11 to 14) having different contents, the content of the high dielectric constant particles were changed without increasing the high dielectric constant particles, and the thickness of the first glass ceramic green sheet A multilayer wiring board (sample No. 14) having the same thickness of the second glass ceramic green sheet and a multilayer wiring board (sample No. 15) in which the content of high dielectric constant particles is reduced by 0.5% are prepared. did. Further, a glass ceramic green sheet laminate in which three layers of the second glass ceramic green sheet were laminated was produced under the same conditions as in the sample 1, but produced without using the first glass ceramic green sheet. The multilayer wiring board thus obtained had a firing shrinkage rate of 20% in the length direction of one side in the plane direction and a variation in shrinkage of ± 0.3%.

  Next, with respect to the obtained multilayer wiring board, the dimensional accuracy of the multilayer wiring board was measured with a three-dimensional measuring machine from dot marks previously formed on the four corners of the surface. The number of samples was 15, and the number of measurement points was 4 in each sample (between the dot marks on the 4 sides). A total of 60 locations were measured, and the average value was obtained. In this case, a product having a dimensional accuracy (shrinkage variation) of 0.1% or less was determined to be a non-defective product. For the dimensional variation, first, an average value is obtained from 60 values, and a value farthest from the average value is indicated by ±.

  In addition, for the obtained multilayer wiring board, the capacitance value between the internal wiring layers is also measured with an impedance analyzer, and the semiconductor is mounted in comparison with the sample that does not contain the high dielectric constant particles in the raw material powder of the first glass ceramic green sheet It was judged that a device that can operate the device without any problem was appropriate. In Table 1, “O” means proper and “x” means inappropriate.

  Further, the obtained multilayer wiring board is cut and the cross section is polished, a SEM photograph of 1000 times is taken using a scanning microscope (SEM), and is arranged at the center in the stacking direction using an image analyzer. For the second insulating layer (the state after firing of the second glass ceramic green sheet), the porosity was measured as an evaluation of the incidence of voids, and those having a porosity of 5% or less were judged to be appropriate. In Table 1, ○ means a porosity of 3 to 5%, ◎ means 2% or less, and Δ means a value larger than 5%.

Further, the obtained multilayer wiring board was processed into a sintered body of 2 mm □ and a length of 18 mm, and the dimensional change was measured with a laser rangefinder while baking at a rate of 10 ° C./min. The coefficient of thermal expansion at ˜400 ° C. was measured, and those having a coefficient of thermal expansion of 2 × 10 ⁻⁶ to 4 × 10 ⁻⁶ / ° C. were judged to be appropriate. In Table 1, “O” means proper and “x” means inappropriate. These results are shown in Table 1.

  As is clear from the results in Table 1, in the samples of the present invention (sample Nos. 1 to 9), the variation in shrinkage is 0.1% or less, and the capacitance value also hinders an increase in capacitance between wiring layers. Thus, a multilayer wiring board was obtained in which the thermal expansion coefficient of the multilayer wiring board was close to the thermal expansion coefficient of silicon and the generation of voids was suppressed.

In particular, Sample No. 2 was formed using a glass ceramic green sheet laminate in which the second glass ceramic green sheet in the center of the glass ceramic green sheet laminate was sandwiched between the first glass ceramic green sheets having the same thickness. 1-6, compared with the sample (sample No. 7) formed by laminating the first glass ceramic green sheets having different thicknesses on the second glass ceramic green sheet up and down, the glass ceramic green sheet laminate The generation of voids in the second insulating layer (the state after sintering of the second glass ceramic green sheet) disposed near the center was further suppressed, and the porosity could be reduced to 2% or less.

  On the other hand, the sample (sample No. 10) obtained by firing with the resistor has a large shrinkage variation, and the generation of voids cannot be sufficiently suppressed.

  In addition, sample No. 1 was obtained by changing the content of the high dielectric constant particles without increasing the high dielectric constant particles from the upper and lower layers side to the center layer side in the stacking direction of the glass ceramic green sheet laminate. The generation of 11 to 14 voids could not be sufficiently suppressed, and the porosity was higher than 5%. Sample No. 1 in which the content of the high dielectric constant particles contained in the first glass ceramic green sheet was decreased from the upper and lower layers side to the center layer side in the stacking direction of the glass ceramic green sheet laminate. At 15 as well, the porosity was higher than 5%. In addition, sample No. whose content of high dielectric constant particles is 11 mass%. No. 13, the capacity value is high, the thermal expansion coefficient does not match that of silicon, and the thickness of the first glass ceramic green sheet is the same as that of the second glass ceramic green sheet. 14 was a value that hindered the capacity value.

11, 12, 13, 14 ... 1st glass ceramic green sheet 21, 22, 23 ... 2nd glass ceramic green sheet 3 ... Paste for penetration conductors 4 ... Conductive paste 5 for wiring layers ... Glass ceramic green sheet laminate 10 ... Microwave firing furnace 61 ... Furnace wall 62 ... Heat insulation 63 ... Case 64 ... Shelves 65 ... Stands 66 ... Nozzle 67 for supplying atmospheric gas ... Nozzle for exhaust

Claims (2)

Producing a first glass ceramic green sheet and a second glass ceramic green sheet that starts firing shrinkage at a temperature higher than a firing shrinkage end temperature of the first glass ceramic green sheet; A step of producing a composite sheet by laminating the glass ceramic green sheet and the second glass ceramic green sheet, and forming a through hole in the composite sheet to fill with a paste for through conductors and one of the composite sheets A step of applying a conductor paste for wiring layer on the main surface, and laminating a plurality of the composite sheets filled with the paste for through conductors and coated with the conductor paste for wiring layers to produce a glass ceramic green sheet laminate And a step of firing the glass ceramic green sheet laminate. A method of manufacturing a multilayer wiring board according to claim 1, wherein a thickness after firing of the first glass ceramic green sheet is 1/10 to 1/3 of a thickness after firing of the second glass ceramic green sheet. The thickness of the first glass ceramic green sheet and the second glass ceramic green sheet is set, and only the first glass ceramic green sheet is selected from the group of SiC, TiO ₂ , ZnO and Si ₃ N ₄ The high dielectric constant particles contained in the first glass ceramic green sheet from the upper and lower layers side to the center layer side in the stacking direction of the glass ceramic green sheet laminate, while containing one kind of high dielectric constant particles. The ceramic green sheet laminate having a high content is fired by microwave heating. A method for manufacturing a multilayer wiring board, characterized by:   The first glass ceramic green sheet having the same thickness is sandwiched between the second glass ceramic green sheets near the center in the stacking direction of the glass ceramic green sheet laminate. The manufacturing method of the multilayer wiring board as described.

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