JP5268847B2 - Wiring board and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable wiring board which can suppress the increase in resistance values of via conductors and the occurrence of cracks around the via conductors, when the wiring board has a plurality of via conductors with different diameters. <P>SOLUTION: A wiring board 1 includes an insulating substrate 2 which is made of ceramics and via conductors 3 which are provided on the insulating substrate 2. Each via conductor 3 is a tapered shape whose diameter differs at both ends and has an insulating component 5 contained in ceramics, and the larger the diameter in the via conductor 3 becomes, the higher the mass ratio of the insulating component 5 in the via conductor 3 becomes. A required low resistance value can be satisfied in the small diameter side of the via conductor 3, and the occurrence of cracks around the via conductor 3 can be suppressed in the large diameter side of the via conductors 3, so that high reliability can be achieved. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a wiring board including an insulating substrate made of ceramics and a method for manufacturing the wiring board.

  An electronic device in which an electronic component such as a semiconductor substrate or a capacitor on which an integrated circuit is currently formed is connected to a via conductor of a wiring board made of a ceramic substrate on which a circuit having a via conductor is connected via a connection pad. Has been produced and used in various fields. In such an electronic device, in order to connect semiconductor substrates and electronic components having connection terminals of various sizes, in the wiring board, connection pads corresponding to the connection terminals and vias connected to the connection pads are used. It is necessary to arrange the conductors appropriately. Here, the diameter and arrangement of via conductors formed on the ceramic substrate, which is a wiring board, should correspond to the connection pads and wiring conductors set according to the size and type of electronic components connected to the via conductors. Therefore, ceramic substrates having via conductors with various diameters and arrangements are used.

As a method of forming a via conductor on a wiring board, it is common to go through a manufacturing process in which a via hole formed in a ceramic green sheet serving as an insulating substrate made of ceramic is filled with a conductor paste serving as a via conductor and fired. It is. Here, as a method for forming the via hole, a method using a laser such as a CO ₂ laser or a UV-YAG laser is applied instead of a method using a mold in which punching pins made of metal or the like are appropriately arranged. It is becoming. In the case of using the laser, it is possible to reduce the cost for producing a mold having punch pins having various diameters and arrangements corresponding to the diameters and arrangements of the via holes. Further, unlike the case of processing the via hole with a mold, the via hole processed with a laser has a so-called tapered shape in which the diameter of the ceramic green sheet is different between the front surface and the back surface.

  A conductor that forms a via conductor in order to suppress cracks and the like that occur around the via conductor due to a difference in shrinkage behavior between the via conductor and the ceramic that becomes the insulating substrate with respect to a wiring board made of such a ceramic substrate. A method of adding ceramic powder to the paste has been proposed (see, for example, Patent Document 1).

JP 2007-81351

  However, for the via conductor having a taper shape, when ceramic powder is added in the same ratio to the smaller diameter and the larger diameter, the resistance is increased in the smaller diameter, so the via conductor There is a problem that the required low resistance value cannot be satisfied, and electrical signals or the like cannot be satisfactorily passed. On the other hand, the larger the diameter, the larger the absolute amount of the conductor component made of a metal having a larger thermal expansion coefficient than the insulating substrate made of ceramics. Since the thermal shrinkage difference becomes large, there is a problem that cracks are likely to occur in the vicinity of the insulating substrate around the through conductor and in the vicinity of the interface between the through conductor and the insulating substrate. Therefore, in order to connect various types of semiconductor substrates and electronic components, if a via conductor having a large diameter difference between a smaller diameter and a larger diameter is arranged as a via conductor having a tapered shape, the entire via conductor is arranged. If formed using the same conductor paste, there is a problem that it is difficult to simultaneously maintain the resistance value of the via conductor and suppress the occurrence of cracks and the like.

  That is, in a wiring board made of a ceramic substrate on which a via conductor having a tapered shape is formed, both of satisfying a resistance value required for the via conductor and suppressing cracks around the via conductor can be suppressed. There is a problem that a highly reliable wiring board that combines the demands.

  The wiring board of the present invention includes an insulating substrate made of ceramics and a via conductor provided on the insulating substrate, and the via conductor has a tapered shape having different diameters at both ends, and is included in the ceramic. And the mass ratio of the insulating component in the via conductor increases as the diameter of the via conductor increases.

  Preferably, in the wiring board according to the present invention, the via conductor has an end having a smaller diameter exposed on the surface of the insulating substrate.

  Preferably, in the wiring board of the present invention, the insulating component is a glass component having a softening point lower than a shrinkage start temperature obtained by the TMA method of the conductor component of the via conductor, and a firing temperature of the insulating substrate. And the ceramic component having a high shrinkage start temperature obtained by the TMA method, and the ratio of the glass component in the insulating component increases as the diameter of the via conductor increases. .

  A method of manufacturing a wiring board according to the present invention is a method of manufacturing a wiring board including an insulating substrate made of ceramics and a via conductor provided on the insulating substrate, and a preparation step of preparing a plurality of ceramic green sheets; A forming step of forming tapered through holes having different diameters at both ends in the plurality of ceramic green sheets; a filling step of filling the through holes with a conductive paste having an insulating component contained in the ceramic; A lamination step of laminating the plurality of ceramic green sheets and a firing step of firing the laminated ceramic green sheets, and in the filling step, a mass ratio of the insulating component as the diameter of the through-hole increases. The conductive paste is filled so as to be large.

  According to the wiring board of the present invention, since the mass ratio of the insulating component in the tapered via conductor increases as the via conductor diameter increases, the via conductor having a tapered shape is required for the via conductor. Therefore, it is possible to realize a highly reliable wiring board that has both the satisfaction of the low resistance value and the suppression of the occurrence of cracks around the via conductor.

  According to the method for manufacturing a wiring board of the present invention, since the above steps are included, the via conductor having a tapered shape satisfies a low resistance value required for the via conductor and cracks around the via conductor. Therefore, it is possible to manufacture a highly reliable wiring board that has both the ability to suppress the occurrence of the above.

It is sectional drawing which shows an example of embodiment of the wiring board of this invention. (A)-(c) is sectional drawing which showed an example of embodiment of the manufacturing method of the wiring board of this invention in order of a process, respectively.

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

  FIG. 1 is a cross-sectional view showing a configuration example in an example of an embodiment of a wiring board of the present invention. As shown in FIG. 1, the wiring substrate 1 of this example includes an insulating substrate 2 made of ceramics and a plurality of via conductors 3 provided on the insulating substrate 2. The via conductor 3 is a through conductor formed by filling a through hole provided in an insulating layer constituting the insulating substrate 2 with a conductor. In addition, on the surface and inside of the wiring substrate 1, a circuit 4 is provided that is formed of a so-called solid pattern having a large area or a linear line pattern that is a wiring conductor. The plurality of via conductors 3 include a plurality of via conductors having tapered shapes having different diameters at the upper end and the lower end, and each via conductor 3 having the tapered shape includes an insulating component 5. The circuit 4 is provided inside and on the surface of the insulating substrate 2 and includes an insulating component 5 like the via conductor 3. Here, the insulating component 5 is made of ceramics similar to the ceramics included in the insulating substrate 2.

  For example, the insulating substrate 2 made of ceramic is made of an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon carbide sintered body, a silicon nitride sintered body, or a glass ceramic sintered body. Formed of a ceramic material. And the insulating component 5 which consists of ceramics which the via conductor 3 has is also formed with these ceramic materials.

  Here, in the wiring substrate 1 of the present example, the tapered via conductor 3 has a shape with different diameters at both ends, and has an insulating component 5 included in the ceramic forming the insulating substrate 2. The mass ratio of the insulating component 5 in the via conductor 3 increases as the diameter of the via conductor 3 increases. As described above, assuming that the mass ratio of the insulating component 5 in the via conductor 3 increases as the diameter of the via conductor 3 increases, the mass ratio of the insulating component 5 is made the same for the entire via conductor 3. Compared to the case, it is possible to suppress the resistance value of the smaller diameter from becoming too large and satisfy the desired low resistance value, while adjusting the thermal expansion coefficient of the via conductor 3 having the larger diameter. Thus, the generation of cracks in the peripheral insulating substrate 2 can be suppressed.

The mass ratio of the insulating component 5 in the via conductor 3 varies depending on the ceramic material used for the insulating substrate 2 and the conductor component used for the via conductor 3, and may be adjusted as appropriate so that the difference in thermal expansion coefficient between the two is reduced. For example, the insulating substrate 2 is made of glass ceramics containing Al ₂ O ₃ powder and SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ glass powder, the via conductor 3 is made of copper (Cu) as a conductor component, and is insulated. If the component 5 is composed of SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ glass powder and SiO ₂ powder, the amount of the insulating component 5 added (mass) when the smaller diameter of the via conductor 3 is 30 μm Ratio) is 5 to 10% by mass, and when the larger diameter is 150 μm, the addition amount (mass ratio) of the insulating component 5 is increased to 15 to 30% by mass, and the smaller diameter of the via conductor 3 is In this case, the required value can be satisfied by keeping the resistance value low, and cracks can be sufficiently suppressed in the peripheral insulating substrate 2 when the diameter is larger.

  In the wiring board 1 of this example, it is preferable that the end portion of the via conductor 3 having the smaller diameter is exposed on the surface of the insulating substrate 2. As described above, when the end portion of the tapered via conductor 3 having a smaller diameter is exposed on the surface of the insulating substrate 2, the amount of the insulating component 5 added is smaller in the via conductor 3 having a smaller diameter. Therefore, when plating is performed on the end portion of the via conductor 3 exposed on the surface of the wiring substrate 1 after firing, a plating film is easily formed on the end portion surface of the via conductor 3, and an electronic component is connected. In this case, it is possible to improve the bonding strength and bonding reliability of the solder.

  In the wiring board 1 of this example, the insulating component 5 includes a glass component whose softening point is lower than the shrinkage start temperature obtained by the TMA method (Thermomechanical Analysis) of the conductor component of the via conductor 3, and the TMA method. It is preferable that the shrinkage start temperature obtained by the above is made of a ceramic component higher than the firing temperature of the insulating substrate 2, and the ratio of the glass component in the insulating component 5 is preferably increased as the diameter of the via conductor 3 is increased.

  This is because the insulating component 5 has a glass component having a softening point lower than the shrinkage start temperature obtained by the TMA method of the conductor component constituting the via conductor 3 and the shrinkage start obtained by the TMA method than the firing temperature of the insulating substrate 2. A glass component having a different shrinkage start temperature in accordance with a difference in shrinkage start temperature between the conductor component of the via conductor 3 and the insulating substrate 2 at the time of firing the wiring substrate 1 by being composed of a ceramic component having a high temperature. This is because the occurrence of cracks due to the difference between the shrinkage start temperatures of the via conductor 3 and the insulating substrate 2 can be suppressed by adjusting the ratio of the ceramic component to adjust the shrinkage start temperature of the via conductor 3. For example, when a material having a shrinkage start temperature lower than that of the insulating substrate 2 is used as the conductor component used for the via conductor 3, by increasing the shrinkage start temperature of the via conductor 3 by increasing the ratio of the ceramic component, Further, when a material having a higher shrinkage start temperature than the insulating substrate 2 is used as the conductor component, the sintering behavior of the via conductor 3 is reduced by increasing the glass component ratio and lowering the shrinkage start temperature of the via conductor 3. Can be adjusted so as to approximate the sintering behavior of the insulating substrate 2.

  If the diameter of the via conductor 3 is large, the glass component diffusing from the insulating substrate 2 to the via conductor 3 during firing does not reach the center of the via conductor 3. In the center portion of the few via conductors 3, the conductor component does not sinter and the holes are easily generated, and the electrical resistance value of the via conductor 3 is increased. On the other hand, since the glass component is also present in the central portion of the via conductor 3 by increasing the ratio of the glass component as the diameter of the via conductor 3 increases, Since the sintering is sufficiently promoted even in the central portion, it is possible to suppress an increase in the resistance value of the via conductor.

  Here, the shrinkage initiation temperature obtained by the TMA method for the conductor component of the via conductor 3 and the ceramic component of the insulating component 5 was obtained by measurement according to JIS R3102 “Test method for average linear expansion coefficient of glass”. The sample powder consisting of the conductor component of the via conductor 3 and the sample powder consisting of the ceramic component of the insulating component 5 are each passed through a 250 mesh sieve, and the obtained powder is put into a molding die and about 3 to 10 MPa. A cylindrical bulk having a diameter of 6 mm and a height of 10 mm is formed by pressing at normal temperature for 5 to 30 seconds at a pressure of 10 ° C./min in an atmosphere such as air or nitrogen. It is the temperature at which the bulk starts to shrink, as determined by measuring the change in the height in the height direction by a thermomechanical analysis (TMA) method while firing at a heating rate.

  The ratio of the glass component in the insulating component 5 is, for example, the ratio of the glass component in the insulating component 5 when the smaller diameter of the via conductor 3 is 30 μm, and the diameter of the via conductor 3 is large. If the ratio of the glass component in the insulating component 5 in the case of 150 μm is 30 to 80% by mass, the via conductor 3 is obtained if the added amount of the insulating component 5 is 3 to 8% by mass and 10 to 20% by mass, respectively. The generation of cracks in the insulating substrate 2 in the periphery of the via conductor 3 can be suppressed, and the generation of the central hole in the via conductor 3 having a larger diameter of 150 μm can be suppressed. Moreover, since the addition amount of the insulating component 5 added to the via conductor 3 can be suppressed by adjusting the ratio of the glass component, the resistance value of the via conductor 3 can be suppressed.

Examples of the glass component in the insulating component 5 include SiO ₂ —B ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO system ( However, M represents Ca, Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ₁ O—M ₂ O system (where M 1 and M 2 are the same or different, and Ca, Sr, Mg, Ba or Zn _{shown), SiO 2 -B 2 O 3} -Al 2 O 3 -M1O-M2O -based (where, M1 and M2 are as defined _{above), SiO 2 -B 2 O 3} -M3 2 O system (however, M3 Represents Li, Na, or K), or SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M3 ₂ O (where M3 is the same as above), Pb glass, Bi glass, and the like. It is done.

  The softening point of the glass component is preferably about 10 to 100 ° C. lower than the shrinkage start temperature obtained by the TMA method of the conductor component of the via conductor 3. If it is this range, the effective shrinkage adjustment of the via conductor 3 by a glass component will be attained, and it is preferable. For example, if the shrinkage starting temperature obtained by the TMA method of the conductor component of the via conductor 3 is about 800 ° C., the glass component of the insulating component 5 having a softening point of about 700 to 790 ° C. can be used. Effective shrinkage adjustment of the via conductor 3 by the component becomes possible.

Further, as the ceramic component of the insulating component 5, the same ceramic as that constituting the insulating substrate 2 can be used, for example, a composite of Al ₂ O ₃ , SiO ₂ , ZrO ₂ and an alkaline earth metal oxide. And oxides, composite oxides of TiO ₂ and alkaline earth metal oxides, and composite oxides containing at least one selected from Al ₂ O ₃ and SiO ₂ (for example, spinel, mullite, cordierite), and the like. .

  The shrinkage start temperature obtained by the TMA method of the ceramic component of the insulating component 5 is preferably higher by 100 ° C. or more than the firing temperature of the insulating substrate 2. If it is this range, the effective shrinkage adjustment of the via conductor 3 by a ceramic component will be attained, and it is preferable. For example, if the firing temperature of the insulating substrate 2 is about 1000 ° C., the ceramic component of the insulating component 5 is made of alumina, silica, titanium dioxide or the like whose shrinkage start temperature determined by the TMA method is 1100 ° C. or higher. Thus, effective shrinkage adjustment of the via conductor 3 is possible.

  Examples of the conductor material for the via conductor 3 and the circuit 4 include tungsten (W), molybdenum (Mo), manganese (Mn), gold (Au), silver (Ag), copper (Cu), palladium (Pd), and the like. One type or two or more types of platinum (Pt) can be used, and can be selectively used depending on the material of the insulating substrate 2. Here, it is preferable to use copper, silver, or gold because resistance values of the via conductor 3 and the circuit 4 are low, and high-frequency signals are easily passed.

  In addition, when the circuit 4 has a so-called solid pattern having a large area or a linear line pattern as a wiring conductor having the same insulating component as that of the insulating component 5, the mass ratio is a pattern having a large area. By making the mass ratio of the insulating component 5 in a certain solid pattern higher than the mass ratio in the line pattern which is a linear pattern, the generation of cracks in the insulating substrate 2 around the solid pattern is the same as in the via conductor 3. And the resistance value of the line pattern can be kept low, which is preferable. For example, in a line pattern having a width of about 50 μm, the insulation component has a mass ratio of about 1 to 8 mass%, and in the case of a solid pattern, the insulation component has a mass ratio of about 5 to 15 mass%. The occurrence of cracks in the substrate 2 can be suppressed, and the resistance value of the line pattern can be kept low.

  Next, an example of an embodiment of a method for manufacturing a wiring board according to the present invention will be described with reference to FIG. 2 taking the wiring board 1 as an example. 2A to 2C are cross-sectional views showing an example of a method of manufacturing the wiring board 1 in the order of steps. In FIG. 2, parts corresponding to the wiring board 1 shown in FIG. Is shown.

First, as shown in FIG. 2A, a tapered via hole 7 which is a through hole for forming a via conductor 3 having different diameters at both ends is formed on a ceramic green sheet 6 to be an insulating substrate 2. A plurality are formed. The ceramic green sheet 6 is obtained by kneading raw material powders such as aluminum oxide, silicon oxide and calcium oxide together with a binder resin and a solvent to obtain a slurry, and this slurry is formed into a sheet on a carrier by a doctor blade method or a lip coater method. It is formed by molding. Here, as a method of forming the tapered via hole 7 in the ceramic green sheet 6, a method of irradiating a laser beam such as a CO ₂ laser or a UV-YAG laser can be employed. Here, if a method of irradiating laser light is used as a method of forming the via hole 7, the ceramic green sheet 6 can be used for forming the via hole 7 with a carrier attached. This is preferable because the dimensional variation can be suppressed.

  Next, as shown in FIG. 2B, the conductive paste to be the via conductor 3 is filled into the tapered via hole 7, and the conductive paste to be the circuit 4 is formed on the surface of the ceramic green sheet 6 so as to be connected thereto. Apply. In this case, either the step of filling the via hole 7 with the conductive paste or the step of applying the conductive paste to the surface of the ceramic green sheet 6 may be performed first. Further, as a method of filling the via hole 7 with the conductive paste and a method of applying the conductive paste to the surface of the ceramic green sheet 6, a screen printing method in which the conductive paste is applied from an opening of a printing mask, an inkjet, a dispenser, etc. Any method such as a method of directly drawing the conductor paste can be applied.

  Such a conductor paste is prepared by preparing a binder resin and a solvent in the conductor particles 8 serving as the conductor component and the insulating particles 9 serving as the insulating component 5, and heating and mixing them.

  The conductor particles 8 are made of, for example, metal powder such as tungsten (W), molybdenum (Mo), manganese (Mn), gold (Au), silver (Ag), copper (Cu), palladium (Pd), or platinum (Pt). It is manufactured by an atomization method or a reduction method, and may be subjected to treatment such as oxidation prevention or aggregation prevention as necessary. When there are two or more kinds of conductor particles 8, two or more kinds of powders may be mixed, or a powder in which two or more kinds of metal materials are integrated by an alloy or a coating may be used. Moreover, fine particle or coarse powder may be removed by classification or the like to adjust the particle size distribution to a desired distribution.

Insulating particles 9 serving as the insulating component 5 are composed of SiO ₂ —B ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system, and SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO system. (Wherein M represents Ca, Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ₁ O—M ₂ O system (where M 1 and M 2 are the same or different and Ca, Sr, Mg, Ba or Zn ), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ₁ O—M ₂ O system (where M 1 and M 2 are the same as above), SiO ₂ —B ₂ O ₃ —M _{3 2} O system (wherein M3 represents Li, Na, or K), or SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M3 ₂ O (where M3 is the same as above), Pb glass, Bi glass, etc. Glass powder, Al ₂ O ₃ , Si A composite oxide of O ₂ , ZrO ₂ and an alkaline earth metal oxide, a composite oxide of TiO ₂ and an alkaline earth metal oxide, and a composite containing at least one selected from Al ₂ O ₃ and SiO ₂ A ceramic powder such as an oxide (for example, spinel, mullite, cordierite) manufactured by an atomizing method, a powder pulverized by a ball mill or the like can be used. Further, if necessary, treatment such as oxidation prevention or aggregation prevention may be performed. When two or more kinds of insulating particles 9 are used, two or more kinds of powders may be mixed, or a powder in which two or more kinds of insulating materials are integrated by coating or the like may be used. Moreover, fine particle or coarse powder may be removed by classification or the like to adjust the particle size distribution to a desired distribution.

  Here, in order to adjust the mass ratio of the insulating component 5 in the tapered via conductor 3 so as to increase as the diameter of the via conductor 3 increases, the added amount of the insulating particles 9 contained in the conductor paste ( A plurality of ones having adjusted mass ratios) are produced according to the diameter of the via hole 7 (via conductor 3), and a conductor paste according to the diameter of the via hole 7 is used to connect to the via hole 7. The conductor paste is filled in several times. Thereby, the tapered via conductor 3 in which the mass ratio of the insulating component 5 increases as the diameter increases can be formed. Here, the number of times of filling may be set based on a difference in diameter between both ends of the via conductor 3, a difference in mass ratio of the insulating component 5 at both ends of the via conductor 3, or the like. For example, if the difference in diameter between both ends of the via conductor 3 is 100 μm or less, or if the difference in the mass ratio of the insulating component 5 between both ends of the via conductor 3 is 10% or less, the diameter of the via hole 7 The filling of the conductor paste with a small amount (mass ratio) of the insulating particles 9 added to the small side of the conductor and the filling of the conductor paste with a large amount (mass ratio) of the insulating particles 9 added to the side having the larger diameter of the via hole 7 What is necessary is just to make it the frequency | count of filling about 2 times. In addition, if the difference in diameter between both ends of the via conductor 3 is larger than 100 μm, or if the difference in the mass ratio of the insulating component 5 between both ends of the via conductor 3 is larger than 10%, the number of times of filling is 3 About once. By doing in this way, it can be set as the mass ratio of the insulation component 5 according to a diameter over the whole area of the length (depth) direction of the via conductor 3. FIG.

  As the binder resin contained in the conductor paste, those conventionally used in the conductor paste can be used. For example, acrylic (a homopolymer or copolymer of acrylic acid, methacrylic acid or esters thereof, specifically acrylic ester copolymer, methacrylic ester copolymer, acrylic ester-methacrylic ester copolymer Homopolymers or copolymers of polyvinyl butyral, polyvinyl alcohol, acrylic-styrene, polypropylene carbonate, cellulose, etc. In selecting the resin, an acrylic or alkyd organic binder is preferable in consideration of decomposition and volatility in the firing step. The amount of resin added varies depending on the type of conductor particles 8 and insulating particles 9 used in the conductor paste, but is an amount that can be easily decomposed and removed during firing and can disperse the conductor particles 8 and insulating particles 9 well. As a guide, about 5 to 20% by mass with respect to the conductor particles 8 is desirable. As the solvent, plasticizers such as terpineol, butyl carbitol acetate and phthalic acid can be used.

  Here, when a penetration inhibitor that suppresses penetration of the solvent component in the conductor paste into the ceramic green sheet 6 is added to the conductor paste for filling the via hole 7, the conductor paste is filled when the conductor paste is filled. Therefore, the solvent contained in the conductor paste in the ceramic green sheet 6 becomes difficult to be absorbed by the ceramic green sheet 6, so that the viscosity of the conductor paste is hardly increased during filling, and stable filling can be performed. Thus, when the conductor paste has a penetration inhibitor that suppresses penetration of the solvent component into the ceramic green sheet 6, especially when the diameter of the via hole 7 is small and when the viscosity of the conductor paste is high. It becomes easy to fill the via hole 7 with the conductive paste. As a result, cracks due to drying shrinkage of the conductor paste are unlikely to occur in the peripheral portion of the via conductor 3 or in the via conductor 3.

  The amount of the penetration inhibitor added may be adjusted according to the diameter of the via hole 7. Specifically, the larger the diameter of the via hole 7, the smaller the amount of the penetration inhibitor added. In this way, in the via hole 7 having a large diameter, it is difficult for the conductive paste to bleed into the back surface of the ceramic green sheet 6 when the conductor paste is embedded, and also in the via hole 7 having a small diameter. Therefore, cracks are less likely to occur in the peripheral portion of the via conductor 3 and the peripheral insulating substrate 2 and in the via conductor 3. In this case, it is possible to perform satisfactory filling by preparing a conductive paste with a plurality of added amounts being changed, and properly using the paste according to the size of the diameter of the via hole 7 and filling a plurality of times.

  For example, when the diameter of the via hole 7 is as small as 40 μm, the addition amount of such a penetration inhibitor is in the range of 10 to 20% by mass, while the diameter of the via hole 7 is as large as 100 μm. When the range is 0.1 to 5% by mass, the filling property can be improved when the diameter of the via hole 7 is as small as about 40 μm, while the diameter of the via hole 7 is 100 μm. When it is as large as possible, the occurrence of bleeding of the conductor paste can be reduced, which is preferable.

  Moreover, it is preferable that a penetration inhibitor contains castor oil. Since the penetration inhibitor contains castor oil, the solvent is retained in the network structure contained in the castor oil, so that the solvent can effectively prevent the solvent from penetrating into the ceramic green sheet 6 and volatilizing. it can. Also, by adjusting the holding power of the network structure with castor oil, it is possible to release the solvent from the network structure when filling the conductor paste, in which case the viscosity of the conductor paste can be reduced. It becomes easy to fill the via hole 7 with the conductive paste. Therefore, generation of cracks due to drying shrinkage of the conductor paste can be suppressed in the periphery of the via conductor 3 and inside the via conductor 3. As the castor oil used here, one added with hydrogen can be used. Hydrogenated castor oil can strengthen the holding power of the solvent by hydrogen bonding with the solvent contained in the conductor paste, so that the conductor paste can be satisfactorily filled even with a smaller amount of penetration inhibitor added. Therefore, it is preferable.

  Further, in the production of the conductor paste, according to the method in which the permeation inhibitor, the binder resin, and the solvent are heated and mixed in advance and then heated and mixed with the conductor particles 8 and the insulating particles 9, the conductor particles 8 and the insulating particles are insulated. Since the penetration inhibitor does not adhere to the surface of the particles 9 and solidifies, and the penetration inhibitor is easily dispersed in the binder resin and the solvent (hereinafter also referred to as a resin), the addition of less penetration inhibitor Even in the amount, when the conductor paste is filled, the solvent contained in the conductor paste hardly penetrates into the ceramic green sheet 6 and is not easily absorbed. At this time, it is preferable that the temperature at which the permeation inhibitor and the resin are heated in advance is higher than the temperature at which the conductor paste is heated. This is because in such a case, there is no separation between the permeation inhibitor and the resin due to changes over time, and the state after dispersion becomes more stable. The temperature at which the permeation inhibitor and the resin are heated in advance varies depending on the type of the resin and the permeation inhibitor, but when using acrylic resin as the binder resin and terpineol as the solvent, the temperature ranges from 30 to 80 ° C. If it is left after dispersion, the conductor paste can be prevented from separating into a resin or the like and a penetration inhibitor, and the conductor paste to the via hole 7 can be added even with a smaller amount of penetration inhibitor. During the filling, the solvent contained in the conductor paste is hardly absorbed by the ceramic green sheet 6.

  Also, the same conductor paste may be used as the conductor paste filled in the via hole 7 for forming the via conductor 3 and the conductor paste applied to the surface of the ceramic green sheet 6 for forming the circuit 4. If the particle size distribution of the conductor particles 8 contained in the conductor paste filled in the via hole 7 is wider than the particle size distribution of the conductor particles 8 contained in the conductor paste forming the circuit 4, the shrinkage behavior during firing is good. Adjustment becomes easier, and cracks are less likely to occur in the insulating substrate 2 around the via conductor 3.

  Further, the via hole 7 is formed by irradiating the ceramic green sheet 6 placed on a carrier such as a PET film with laser light, and the via hole 7 is filled with a conductive paste. After the filling, the ceramic green sheet 6 is filled. When the carrier is peeled off, the conductor paste does not bleed onto the surface of the ceramic green sheet 6, so even if the via holes 7 are formed at a high density, short-circuiting between the via conductors 3 due to the oozing of the conductor paste filled therewith is caused. Less likely to occur.

  Finally, as shown in FIG. 2 (c), a plurality of ceramic green sheets 6 filled with a conductive paste in via holes 7 and coated with a conductive paste to be a circuit 4 on the surface are laminated, and the laminate is fired. As a result, the wiring board 1 is completed. The insulating component 5 included in the via conductor 3 and the insulating component included in the circuit 4 are subjected to a destructive inspection such as polishing the cross section of the wiring board 1 after firing or a nondestructive inspection using transmitted light by X-rays or the like. The state of can be confirmed.

  As a method of calculating the size of the particle size of the insulating component 5, for example, a cross section of the via conductor 3 is polished to measure the maximum length of the insulating component 5 and the area of the insulating component 5, and a circle having the same area as that area. Insulating component 5 is detected by detecting the region of insulating component 5 from an image obtained by projecting via conductor 3 with transmitted X-rays, or by using X-ray tomographic image of via conductor 3. There is a method in which the portion 5 is detected and the volume of the insulating component 5 is measured, and the diameter of the sphere having the same volume as the measured volume is made the size of the particle size of the insulating component 5. Similarly, the mass ratio of the insulating component 5 in the via conductor 3 is also determined by measuring the area of the insulating component 5 in the area of the via conductor 3 or the volume of the insulating component 5 in the volume of the via conductor 3. The mass ratio of the insulating component 5 in 3 can be calculated.

Here, when a low-temperature sintered material such as glass ceramics is used as the insulating substrate 2, a constrained green sheet is further laminated and fired on the upper and lower surfaces of a laminate in which a plurality of ceramic green sheets 6 are laminated. It is preferable to remove the constraining sheet because it is possible to obtain the wiring board 1 with higher dimensional accuracy. This constrained green sheet is a green sheet mainly composed of a hardly sinterable inorganic material such as Al ₂ O ₃ and does not shrink when the insulating substrate 2 is fired. In the laminate in which the constrained green sheets are laminated, shrinkage in the laminating plane direction (xy plane direction) is suppressed by the constraining green sheet that does not shrink, and mainly shrinks in the laminating direction (z direction). The accompanying dimensional variation of the insulating substrate 2 is suppressed.

  Here, if the circuit 4 formed on the surface of the wiring board 1 includes an insulating component, the bonding strength between the two increases due to the reaction between the insulating component included in the circuit 4 and the constrained green sheet, and the contraction is less likely. However, when the ratio of the insulating component is large, particularly when the contact area of the circuit 4 is small, the bonding strength between the circuit 4 and the constrained green sheet is increased, and the constrained green sheet cannot be completely removed after firing. Or the circuit 4 may be peeled off from the insulating substrate 2. Conversely, when the ratio of the insulating component is small, particularly when the contact area of the circuit 4 is large, the bonding strength between the circuit 4 and the constraining green sheet is weakened, and the dimensional variation of the insulating substrate 2 may occur. . In this case, if the mass ratio of the insulating component to be contained is changed according to the size of the area of the circuit 4 as described above, the constrained green sheet can be easily removed regardless of the contact area with the circuit 4. This is preferable because the bonding strength between the circuit 4 and the constraining green sheet is moderate and the dimensional variation of the insulating substrate 2 is suppressed.

  In addition to the hardly sinterable inorganic component, the constrained green sheet contains a glass component having a softening point equal to or lower than the firing temperature of the insulating substrate 2, for example, the same glass component as the glass component in the ceramic green sheet 6. Good. If it does so, this glass component will soften during baking and it will couple | bond with the ceramic green sheet 6, the coupling | bonding of the ceramic green sheet 6 and a restraint green sheet will become strong, and more reliable restraint force will be obtained. At this time, the content of the glass component is preferably 0.5 to 15% by mass with respect to the amount of the inorganic component including the hardly sinterable inorganic component and the glass component, thereby improving the binding force. In addition, the firing shrinkage of the constrained green sheet is suppressed to 0.5% or less.

  In this case, since the insulating component included in the circuit 4 reacts with the glass component included in the constraining green sheet, even if the mass ratio of the insulating component included in the circuit 4 is further reduced, It is preferable because the bonding strength can be appropriately secured and the dimensional variation of the insulating substrate 2 can be suppressed.

  Examples of a method for removing the constraining sheet from the wiring substrate 1 after firing include polishing, water jet, chemical blasting, sand blasting, wet blasting (a method of spraying abrasive grains and water by air pressure), and the like.

  The via conductor 3 includes not only one that penetrates each insulating layer constituting the insulating substrate 2 but also one that penetrates the entire insulating substrate 2.

  The surface of the circuit 4 formed on the surface of the wiring substrate 1 after firing is good for preventing corrosion or as a means for connecting to an external wiring substrate or a mounted electronic component such as solder or metal wire. For easy connection, nickel (Ni) or gold (Au) may be plated.

  In addition, this invention is not limited to the example of above-mentioned embodiment, A various deformation | transformation is possible if it is in the range of the summary of this invention.

[First embodiment]
A first embodiment of the wiring board of the present invention will be described below.

First, 100 parts by weight of a mixture of ceramic powder made of Al ₂ O ₃ and glass powder made of SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ , 10 parts by weight of an acrylic binder resin, and plasticizer 1 part by mass was added, and toluene and ethyl acetate were mixed as a solvent by a ball mill for 40 hours to prepare a slurry. A ceramic having a thickness of 50 μm is coated from this slurry on a support made of a sheet of polyethylene terephthalate (PET) at a molding speed of 2 m / min and a molding sheet width of 250 mm using a die coater sheet molding machine. A green sheet was formed.

Next, glass powder having a softening point of 600 ° C. made of SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ and SiO ₂ powder were mixed at a mass ratio of 1: 1 with respect to Cu powder as the conductor particles. A solvent composed of an acrylic binder resin and terpineol (TPO) added as an insulating particle in an amount of 3, 5, 10, 15, 20, 30 and 40% by mass (corresponding to the mass ratio of the insulating component) To prepare a conductor paste.

Next, a CO ₂ laser device is used as a laser device for generating laser light, and the ceramic green sheet has a taper-shaped through hole as a via hole having a smaller diameter of 30 μm and a larger diameter of 150 μm. A total of 400 holes were formed in 20 rows vertically and horizontally at 200 μm intervals. The formed through-holes were filled with conductor pastes with different amounts of insulating particles. Four ceramic green sheets embedded with this conductive paste were stacked and heat-pressed at a pressure of 5 MPa and a temperature of 80 ° C. in the thickness direction to produce a ceramic green sheet laminate. Then, in order to remove organic components such as binder resin and solvent in the obtained ceramic green sheet laminate and carbon remaining after decomposition of the organic components, in a nitrogen atmosphere containing water vapor with a partial pressure of 7.33 kPa After performing a heat treatment that is held at a temperature of about 700 ° C. for 1 hour and then holding in a reducing atmosphere at a temperature of about 1000 ° C. for 1 hour, the mass ratio of the insulating components in the via conductor is different. 7 wiring board was produced.

  And about the wiring board of these samples 1-7, the presence or absence of the crack generation | occurrence | production of a via conductor vicinity was observed with the binocular microscope, the electrode terminal of the resistance measuring device was applied to the front and back of the via conductor, and the resistance value of the via conductor was measured. .

  Table 1 shows the amount of insulating particles added to the conductor paste (mass ratio of insulating components) and the results of evaluation of cracks and resistance values for Samples 1 to 7.

  In the results shown in Table 1, “◯” in the “crack” column indicates that the generation of cracks in the vicinity of the via conductor was not observed and was excellent. On the other hand, “Δ” indicates that the occurrence of a slight crack was confirmed in the vicinity of some via conductors, although there was no practical problem. In addition, “◯” in the “resistance value” column indicates that the required resistance value is sufficiently satisfied and is excellent. On the other hand, “Δ” indicates that the resistance value of some via conductors is slightly high at the upper limit of the required value.

  As is clear from the results shown in Table 1, Samples 1, 2, and 3 in which the amount of insulating particles added to the conductor paste (mass ratio of insulating components in the via conductor) is less than 15 mass% are slightly close to the via conductor. Cracks occurred (indicated by “Δ” in the “crack” column in the table). This crack was generated in the vicinity of both ends in the sample 1 and on the end side having a diameter of 150 μm in the samples 2 and 3. In addition, in the samples 4, 5, 6, and 7 in which the amount of insulating particles added to the conductor paste (mass ratio of insulating components in the via conductor) is more than 10 mass%, the resistance value is slightly high at the upper limit of the required resistance value. The values are shown (indicated by “Δ” in the column of “resistance value” in the table). As described above, in the tapered via conductors, in the samples 1 to 7 having the same insulating component added amount, no cracks are generated in the vicinity of the via conductor, and no resistance requirement value is satisfied. (Indicated by “△” in the “overall judgment” column in the table).

  Next, the conductive paste from the support side is changed so that the content of the insulating component varies depending on the size of the ceramic green sheet, as described above, and filled and embedded in multiple times. Except for the above, the wiring boards of Examples 1 to 20 for evaluation were produced in the same manner as described above. Filling the through-holes with the conductive paste is performed by filling the end portion having a diameter of 30 μm with the conductive paste having an added amount of insulating particles of 3, 5, 10, and 15% by mass and having a diameter of 150 μm. The part side was filled with a conductive paste in which the amount of insulating particles added was 10, 15, 20, 30, 40% by mass.

  And about the wiring board of these Examples 1-20, the presence or absence of the crack generation | occurrence | production of a via conductor vicinity is observed with a binocular microscope, and the resistance value of a via conductor is measured by applying the electrode terminal of a resistance measuring device to the front and back of a via conductor. did.

  Table 2 shows the amount of insulating particles added to the conductor paste (mass ratio of insulating components) and the results of evaluation of cracks and resistance values for Examples 1 to 20.

  In the results shown in Table 2, “◯” and “Δ” in the “Crack” column indicate the results of evaluation based on the same criteria as Samples 1 to 7 shown in Table 1.

  As is apparent from the results shown in Table 2, the amount of insulating particles added to the conductor paste at the end with a diameter of 30 μm (mass ratio of insulating components in the via conductor) is less than 5% by mass (at 3% by mass). In the first, second, third, fourth, fifth, sixth, eleventh and sixteenth embodiments, the added amount of the insulating particles at the end with a diameter of 150 μm is less than 15 mass% (10 mass%). A slight crack occurred in the vicinity of the conductor (indicated by “Δ” in the “crack” column in the table). Among them, in Examples 1, 2, 3, 4 and 5, cracks occurred on the end side of the via conductor having a diameter of 30 μm, and in Examples 1, 6, 11 and 16, the end side of the via conductor having a diameter of 150 μm. Cracks occurred. In addition, the amount of insulating particles added at the end with a diameter of 30 μm is more than 10% by mass (15% by mass) Examples 16, 17, 18, 19, 20 and the insulating particles at the end with a diameter of 150 μm In Examples 5, 10, 15, and 20 in which the amount of addition was more than 30% by mass (40% by mass), the resistance value was slightly higher than the upper limit of the required resistance value (“Resistance value in the table” ”Is indicated by“ Δ ”).

  On the other hand, the addition amount of the insulating particles at the end portion having a diameter of 30 μm is 5% by mass and 10% by mass, and the addition amount of the insulating particles at the end portion having a diameter of 150 μm is 15% by mass, 20% by mass and 30%. In Examples 7, 8, 9, 12, 13, and 14 which are mass%, there was no occurrence of cracks in the vicinity of the via conductor, and the resistance requirement value was sufficiently satisfied (see “General” in the table). "Indicated in the" judgment "column by" O ").

  From the results of the first embodiment described above, the low resistance value required for the via conductor is satisfied by increasing the mass ratio of the insulating components in the tapered via conductor as the diameter of the via conductor increases. It can be said that it is possible to realize a wiring board that combines both the above and the ability to suppress the occurrence of cracks around the via conductor.

[Second Embodiment]
A second embodiment of the wiring board of the present invention will be described below.

First, 100 parts by mass of ceramic powder composed of Al ₂ O ₃ and glass powder composed of SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ , 10 parts by mass of an acrylic binder resin, and a plasticizer 1 part by mass was added, and toluene and ethyl acetate were mixed as a solvent by a ball mill for 40 hours to prepare a slurry. A ceramic having a thickness of 50 μm is coated from this slurry on a support made of a sheet of polyethylene terephthalate (PET) at a molding speed of 2 m / min and a molding sheet width of 250 mm using a die coater sheet molding machine. A green sheet was formed.

Next, a glass powder having a softening point of 600 ° C. and SiO ₂ powder made of SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ is mixed with Cu powder as the conductor particles at 9.5: 0.5, 9: 1, 7 : 3,5: 5,3: 7,1: 9 and 0.5: 9.5 (mass ratio) mixed as insulating particles, 1, 3, 5, 10, and 15 masses with respect to Cu powder, respectively % (Corresponding to the mass ratio of insulating components) and mixed with a solvent consisting of an acrylic binder resin and terpineol (TPO) to produce a conductor paste. Incidentally, shrinkage initiation temperature obtained by the TMA method of Cu powder is 800 ° C., shrinkage initiation temperature obtained by SiO ₂ powder TMA method were 1100 ° C. or higher.

Next, a CO ₂ laser device is used as a laser device for generating laser light, and tapered through holes as via holes having diameters of 30 μm and 150 μm at both ends are vertically and horizontally spaced at intervals of 200 μm on the ceramic green sheet. A total of 400 rows were formed. In the formed through-hole, the conductor paste was changed from the support side according to the size of the diameter, and was filled and embedded in a plurality of times. Filling the through hole with the conductive paste is performed by filling the end of the 30 μm diameter conductor paste with 1, 3, 5, 10, 15% by mass of insulating particles, and the corresponding diameter. Insulation in the via conductor with the larger diameter of the via conductor is filled on the end side where the thickness of 150 μm is filled with the conductive paste with the added amount of insulating particles of 3, 5, 10, 15, 20% by mass. The mass ratio of components was increased.

  Four ceramic green sheets each embedded with this conductive paste were stacked and heat-pressed in the thickness direction at a pressure of 5 MPa and a temperature of 80 ° C. to produce a ceramic green sheet laminate. Then, in order to remove organic components such as binder resin and solvent in the obtained ceramic green sheet laminate and carbon remaining after decomposition of the organic components, in a nitrogen atmosphere containing water vapor with a partial pressure of 7.33 kPa Example 21 for evaluation in which the heat treatment is held at a temperature of about 700 ° C. for 1 hour and then held in a reducing atmosphere at a temperature of about 1000 ° C. for 1 hour, and the mass ratio of insulating components in the via conductor is different. Up to 27 wiring boards were produced.

  And about the wiring board of these Examples 21-27, the presence or absence of the crack generation | occurrence | production of a via conductor vicinity was observed with the binocular microscope.

  For these examples, the results of evaluation according to the addition amount (mass ratio) of the insulating component by the diameter of the via conductor and the addition amount of the ceramic component added to the conductor paste are shown on the end side with a diameter of 30 μm. The observation results are shown in Table 3, and the observation results on the end side with a diameter of 150 μm are shown in Table 4, respectively.

  In the results shown in Table 3 and Table 4, “◯” and “Δ” in the “Crack” column indicate the results of evaluation based on the same criteria as Samples 1 to 7 shown in Table 1.

As apparent from the results shown in Table 3, in the first example in which the ratio of the glass powder to the SiO ₂ powder, that is, the glass component: ceramic component = 5: 5, the addition amount of the insulating component in which the crack occurred is 3 Even in the case of mass%, in Examples 21, 22 and 23 in which the glass component: ceramic component was 9.5: 0.5, 9: 1 and 7: 3 and the ratio of the glass component was increased, cracks were generated in the vicinity of the via conductor. It became something without. Further, even when the addition amount of the insulating component was 5% by mass and 10% by mass in which cracks did not occur in the first example, the glass component: ceramic component was 1: 9 and 0.5: 9.5. In Examples 26 and 27 in which the ratio of the components was reduced, a slight crack was observed in the vicinity of the via conductor, although there was no practical problem.

  As is apparent from the results shown in Table 4, even when the addition amount of the insulating component in which cracks occurred in the first example was 10% by mass, the glass component: ceramic component was 9.5: 0.5 and 9: 1. In Examples 31 and 32, no crack was generated in the vicinity of the via conductor, which was excellent. Further, even when the crack was not generated in the first embodiment and the addition amount of the insulating component was 15% by mass, the ratio of the glass component to glass component: ceramic component was 1: 9 and 0.5: 9.5. In Examples 36 and 37 in which the size was reduced, a slight crack was observed in the vicinity of the via conductor, although there was no practical problem.

  In Examples 31 to 37, when the amount of the insulating component added on the end portion side having a diameter of 30 μm was 10% by mass or less, the required resistance value was sufficiently satisfied.

  From the results of the second example, it can be said that the occurrence of cracks can be suppressed by increasing the ratio of the glass component in the insulating component in the via conductor even with a smaller amount of the insulating component.

1: Wiring substrate 2: Insulating substrate 3: Via conductor 4: Circuit 5: Insulating component 6: Ceramic green sheet 7: Via hole 8: Conductor particle 9: Insulating particle

Claims (4)

  Comprising an insulating substrate made of ceramics and via conductors provided on the insulating substrate, the via conductors having tapered shapes having different diameters at both ends, and having an insulating component contained in the ceramics; The wiring board according to claim 1, wherein a mass ratio of the insulating components in the via conductor is increased as a diameter of the via conductor is increased.   The wiring board according to claim 1, wherein an end portion of the via conductor having a smaller diameter is exposed on a surface of the insulating substrate.   The insulating component includes a glass component having a softening point lower than the shrinkage start temperature obtained by the TMA method of the conductor component of the via conductor, and a ceramic having a higher shrinkage start temperature obtained by the TMA method than the firing temperature of the insulating substrate. The wiring board according to claim 1, wherein a ratio of the glass component in the insulating component increases as a diameter in the via conductor increases.   A method of manufacturing a wiring board comprising an insulating substrate made of ceramics and via conductors provided on the insulating substrate, comprising a preparation step of preparing a plurality of ceramic green sheets, and both end portions of the plurality of ceramic green sheets Forming a through hole having a tapered shape with different diameters, a filling step of filling the through hole with a conductive paste having an insulating component contained in the ceramic, and laminating the plurality of ceramic green sheets And filling the conductive paste so that the mass ratio of the insulating component increases as the diameter of the through-hole increases in the filling step. A method for manufacturing a wiring board, comprising:

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