JP2005216998A - Ceramic circuit board and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic circuit board capable of preventing an initial IR failure, an insulation resistance decline, and a reliability loss by securing a proper consistency between an sintering shrinkage behavior of an insulating ceramic layer and that of a metal wiring layer in a sintering process; and to provide a manufacturing method for the ceramic circuit board. <P>SOLUTION: The ceramic circuit board A comprises an insulating board 1 consisting of a plurality of laminated insulating ceramic layers 1a to 1d, and a plurality of metal wiring layers 2 arranged between the insulating ceramic layers 1a to 1d of the insulating board 1, respectively. Each of the metal wiring layers 2 is composed of metal powder and glass, and a glass component spreads from the wiring layer 2 to each insulating ceramic layer 1a to 1d. The content of the glass component in each insulating ceramic layer is made to vary continuously in a range of 10% or more of the thickness of the ceramic layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ceramic circuit board that includes an insulating ceramic layer and a metal wiring layer and is mounted on a wiring board on which an electric element such as a semiconductor element is mounted, an electric element housing package, and the like, and a method for manufacturing the same.

  Conventionally, dielectric ceramics have been widely used for dielectric resonators, dielectric substrates for MICs, waveguides, and the like in high frequency regions such as microwaves and millimeter waves. With the development and spread of mobile communication and the like, the demand for dielectric ceramics as materials for electronic circuit boards and electronic components is increasing.

And as a dielectric ceramic composition for electronic circuit boards and electronic components, glass that can be co-fired with silver or copper, which are highly conductive metals, or a composite material of glass and an insulating ceramic layer, or sintered A so-called low-temperature fired insulating ceramic layer composed of an insulating ceramic layer containing an auxiliary agent has been developed. The raw material powder of such a low-temperature fired insulating ceramic layer is processed into a green sheet containing an organic binder, and the necessary wiring pattern corresponding to the inside and outside is formed by screen printing a conductor paste or necessary Correspondingly, via-hole conductors and through-hole conductors for connecting wiring layers formed between different layers are formed. Thereafter, the green sheet is laminated and the insulating ceramic layer and the metal wiring layer are fired at the same time to form a ceramic circuit board. For example, Patent Document 1 is known as such a ceramic circuit board. This patent document 1 describes a ceramic circuit board in which a metal wiring layer made of silver is formed on an insulating ceramic layer made of glass ceramic that can be fired at 1000 ° C. or lower.
JP-A-5-304368

  However, as described in Patent Document 1, when silver is used as a metal wiring layer and is simultaneously fired with an insulating ceramic layer made of glass ceramics, silver diffuses somewhat in the insulating ceramic layer during firing. Inevitable. Then, when silver diffuses into the low-temperature fired insulating ceramic layer, there is a problem that the insulating resistance of the insulating ceramic layer is lowered and the reliability is also lowered.

  One factor affecting this phenomenon is the consistency of the sintering shrinkage behavior between the insulating ceramic layer and the metal wiring layer during firing. In particular, when the consistency between the two is not obtained, a crack occurs in the insulating ceramic layer during the firing process, and the metal diffuses into the crack, and the insulation resistance value of the insulating ceramic layer between the metal wiring layers is several after firing. A problem (hereinafter referred to as initial IR failure) occurs that decreases to ohms. Even if the initial IR failure does not occur, if the sintering shrinkage behavior of the insulating ceramic layer and the metal wiring layer does not match during firing, there is a problem that the insulation resistance is lowered and the humidity resistance reliability is lowered. This is remarkable in wiring.

  Therefore, in order to match the sintering shrinkage behavior in the past, there are methods such as various changes of both materials in order to match the shrinkage curve of the conductor material and the firing shrinkage curve of the insulating ceramic material, In view of the characteristics of the insulating substrate, it has been very difficult to make a combination that satisfies all the characteristics.

  Therefore, the present invention pays attention to the consistency of the sintering shrinkage behavior of the insulating ceramic layer and the metal wiring layer at the time of firing, and prevents the initial IR failure, the insulation resistance lowering and the reliability failure. It is an object of the present invention to provide a substrate and a manufacturing method thereof.

  According to the present invention, in order to improve the initial IR failure, it is necessary to optimize the shrinkage start temperature of the insulating ceramic layer in the vicinity of the metal wiring layer, and to prevent the insulation resistance from being lowered, the insulating ceramic layer and the metal wiring. In order to match the shrinkage start temperature of the layer and to reduce the reliability of humidity resistance, it is necessary to form a part where the shrinkage start temperature of the insulating ceramic layer continuously changes from the vicinity of the metal wiring layer. Therefore, it is based on the knowledge that improvement of initial IR failure, prevention of decrease in insulation resistance, and improvement of humidity resistance reliability can be achieved.

  That is, the ceramic circuit board of the present invention comprises an insulating substrate formed by laminating a plurality of insulating ceramic layers, and a plurality of metal wiring layers arranged between the insulating ceramic layers of the insulating substrate. The metal wiring layer is composed of metal particles and a glass component, the glass forming component is diffused from the metal wiring layer to the insulating ceramic layer, and the content of the glass forming component is an insulating ceramic. It is characterized by continuously changing over a thickness of 10% or more of the thickness of the layer.

  According to this configuration, by diffusing the glass forming component in the metal wiring layer to a predetermined region, the firing shrinkage behavior of the insulating ceramic layer and the metal wiring layer can be approximated, and the change can be mitigated. Can do.

  Further, according to the present invention, the initial IR can be increased even when the thickness of the insulating ceramic layer is 50 μm or less.

  In addition, the present invention is suitably used when the metal wiring layer is mainly composed of silver and when the insulating ceramic layer is made of low-temperature fired ceramic that can be fired at 1000 ° C. or lower.

  Further, according to the method for manufacturing a ceramic circuit board of the present invention, the surface of the ceramic green sheet containing the insulating ceramic material and the organic binder is applied in the form of a wiring pattern with a conductive material made of metal powder and glass powder. Thereafter, in the method of manufacturing a ceramic circuit board obtained by laminating and firing these, the shrinkage start temperature of the insulating ceramic material is lower than the shrinkage start temperature of the conductor material, and the insulation in the temperature rising process up to the firing temperature The temperature range from the shrinkage start temperature of the ceramic material to the firing temperature is raised at a rate of 5.0 ° C./min or less.

  In particular, when the firing temperature is 1000 ° C. or less and the metal component in the conductor material is mainly composed of silver, the insulating ceramic material is a low-temperature firing comprising a mixture of a glass component and an inorganic filler component. It is suitable when made of a ceramic material.

  In addition, since the difference in shrinkage start temperature between the conductor material and the insulating ceramic material is 300 ° C. or less, initial IR failure can be prevented even if the thickness of the insulating ceramic layer is 50 μm or less, Humidity resistance reliability can be ensured.

  According to the present invention, by raising the temperature range from the shrinkage start temperature of the insulating ceramic material to the firing temperature in the temperature raising process up to the firing temperature as described above at a rate of 5.0 ° C./min or less, As a result of the glass component in the conductive material being diffused into the insulating ceramic material to a predetermined region, the shrinkage start temperature of the insulating ceramic material in the vicinity of the metal wiring layer is approximated to the shrinkage start temperature of the metal wiring layer. As a result, it is possible to suppress the difference in shrinkage of the firing shrinkage behavior between the metal wiring layer and the insulating ceramic material, thereby reducing the insulating ceramic layer between the metal wiring layers. It is possible to obtain a ceramic circuit board that prevents the generation of cracks (prevents initial IR failure) and prevents the decrease in insulation resistance and the reliability.

  According to the present invention, by controlling the diffusion of the glass component in the metal wiring layer, it is possible to achieve consistency in the sintering shrinkage behavior of the insulating ceramic layer and the metal wiring layer during firing. It is possible to realize a ceramic circuit board that prevents the generation of cracks in the insulating ceramic layer between the wiring layers (prevents initial IR failure), and prevents a decrease in insulation resistance and a failure in reliability.

  FIG. 1 shows a schematic sectional view of an example of the ceramic circuit board of the present invention.

  According to the ceramic circuit board A of FIG. 1, a dielectric substrate 1 formed by laminating insulating ceramic layers 1a to 1d, and a metal wiring layer 2 is formed on the surface or inside of the dielectric substrate 1. The dielectric substrate 1 has via conductors 3 penetrating the insulating ceramic layers 1a to 1d in order to connect the metal wiring layers 2 formed in different layers.

  A chip component 4 such as an IC, an inductor, a resistor, or a capacitor is mounted on the surface of the ceramic circuit board by soldering and connected to the metal wiring layer 2 on the surface.

  According to the ceramic circuit board of the present invention, as shown in the schematic enlarged view of FIG. 2, the metal wiring layer 2 is composed of the metal particles 5 and the glass phase 6, and the insulating ceramic in contact with the metal wiring layer 2. At least one component (hereinafter referred to as a glass forming component) that forms a glass phase is diffused from the metal wiring layer 2 to the insulating ceramic layer 1 with respect to the layer 1.

  Further, as shown in FIG. 2, the content of the glass forming component 7 continuously changes from the contact portion with the metal wiring layer 2 over a thickness t of 10% or more of the thickness of the insulating ceramic layer. is important. As described above, the glass-forming component continuously changes over 10% or more of the thickness of the insulating ceramic layer, whereby the initial IR failure can be prevented. If the thickness is less than 10%, this effect cannot be expected. In particular, it is preferably 15% or more, more preferably 20% or more.

  As the metal particles in the metal wiring layer 2 in the present invention, a low-resistance conductor material mainly containing at least one selected from the group consisting of copper, silver, gold, and aluminum is used. In particular, according to the present invention, it is desirable to contain 90% by mass or more of silver.

Further, the glass phase blended in the metal wiring layer 2 contains at least SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , ZnO, PbO, alkaline earth metal oxide (R ¹ O), alkali metal oxidation. Which contains at least one of the products (R ² ₂ O), specifically, SiO ₂ —B ₂ O ₃ —R ¹ O, SiO ₂ —BaO—Al ₂ O ₃ — R ¹ O, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —R ¹ O, SiO ₂ —Al ₂ O ₃ —R ¹ O, and ZnO, PbO, Pb, ZrO ₂ , composition containing TiO ₂ and the like.

  On the other hand, for the insulating ceramic layer 2, a material that can be fired simultaneously with the metal wiring layer 2 is selected, and in particular, a low-temperature fired ceramic material that can be fired at a low temperature of 1050 degrees or less is suitably used. Specifically, (1) a low-temperature fired ceramic material fired at a temperature of 1050 ° C. or lower, particularly 1000 ° C. or lower, comprising a mixture of metal oxides, and (2) a glass powder or a mixture of glass powder and ceramic filler powder. A low-temperature fired ceramic material fired at 1050 ° C. or lower, particularly 1000 ° C. or lower is preferably used.

As the mixture of (1) used, ceramic materials such as BaO—TiO ₂ , Ca—TiO ₂ , and MgO—TiO ₂ are used, and these ceramic materials include SiO ₂ , Bi ₂ O ₃ , and CuO. , Li ₂ O, B ₂ O _{3 and the} like are added appropriately. The glass composition (2) contains at least SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , ZnO, PbO, alkaline earth metal oxide (R ¹ O), alkali metal oxide (R ² ₂ O) containing at least one of the following, specifically, SiO ₂ —B ₂ O ₃ —R ¹ O system, SiO ₂ —BaO—Al ₂ O ₃ —R ¹ O system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —R ¹ O system, SiO ₂ —Al ₂ O ₃ —R ¹ O system, and ZnO, PbO, Pb, ZrO ₂ , TiO _{2 and the} like to these systems. The compounded composition is mentioned. In addition, the glass is an amorphous glass by baking treatment, and by baking treatment, alkali metal silicate, quartz, cristobalite, cordierite, mullite, enstatite, anorthite, serdian, spinel, garnite, Crystallized glass that precipitates at least one crystal of diopside, ilmenite, willemite, dolomite, petalite, and substituted derivatives thereof is used.

Further, as the ceramic filler in (2), Al ₂ O ₃ , SiO ₂ (quartz, cristobalite), forsterite, cordierite, mullite, ZrO ₂ , mullite, forsterite, enstatite, spinel, magnesia, AlN, Si _{In addition to 3} N ₄ , SiC, and TiO ₂ , at least one selected from the group of titanates such as MgTiO ₃ , CaTiO ₃ , SrTiO ₃ , and BaTiO ₃ can be given. In the case of the material (2), it is desirable that the glass is mixed in a proportion of 20 to 80% by mass of glass and 20 to 80% by mass of ceramic filler.

  A method for producing a ceramic circuit board of the present invention will be described. First, a slurry made of an insulating ceramic material is prepared, and a ceramic green sheet is produced using this slurry by a doctor blade method or the like. This slurry is prepared, for example, by adding an organic binder, an organic solvent, and a plasticizer to the composition of the low-temperature fired ceramic material as described above and kneading with a ball mill.

Next, a conductor paste for forming the via conductor 4 and the metal wiring layer 2 is prepared. The conductive paste is obtained by adding an organic vehicle to an inorganic component made of a mixture of a metal material and glass and mixing them. For example, ₃ low-melting glasses such as B ₂ O ₃ —SiO ₂ —BaO, CaO—B ₂ O ₃ —SiO ₂ , and CaO—Al ₂ O ₃ —B ₂ O ₃ —SiO ₂ are applied to copper powder or silver powder. It is added at a ratio of 10% by mass to 10% by mass, and an organic binder such as ethyl cellulose and an organic solvent such as toluene are mixed and homogeneously kneaded with three rollers.

  Here, the shrinkage start temperature of the insulating ceramic material needs to be lower than the shrinkage start temperature of the inorganic material in the conductor paste. When the shrinkage start temperature is reversed, the metal wiring layer starts to be sintered before the insulating ceramic layer starts to be sintered, so that the insulating ceramic layer is cracked to cause the initial IR failure. Because.

  Next, a through hole is formed in a predetermined portion of the ceramic green sheet by a micro drill, laser light, punching, or the like, and a conductive paste is filled in the through hole. Then, a printed pattern is formed on the surface of the ceramic green sheet by a screen printing method or the like.

  Thereafter, ceramic green sheets on which wiring patterns and via conductors are similarly formed are laminated to produce a laminated molded body, which is then fired.

  As the atmosphere during firing, when Cu is used as the conductor material, it can be fired in a non-oxidizing atmosphere such as nitrogen, and when Ag is used, it can be fired in an atmosphere such as air.

  According to the present invention, the temperature is first raised to the firing shrinkage start temperature of the conductor material. The heating rate in this temperature region (A) is suitably 10 to 20 ° C./min. Next, the temperature region (B) from the firing shrinkage start temperature of the conductor material to the shrinkage start temperature of the insulating ceramic material is subsequently raised. The heating rate in this region (B) is suitably 5 to 10 ° C./min. Thereafter, according to the present invention, the temperature range (C) from the shrinkage start temperature to the firing temperature of the insulating ceramic material is raised at a rate of 5.0 ° C./min or less, particularly 3.0 ° C./min or less. is required. The reason for this is that when the rate of temperature increase in the temperature region (C) is faster than 5.0 ° C./min, the diffusion of the glass component in the metal wiring layer does not proceed sufficiently to the insulating ceramic layer. As a result, it is difficult to form a portion in which the content of the glass forming component continuously changes, and the shrinkage start temperature consistency between the insulating ceramic layer and the metal wiring layer cannot be achieved, resulting in an initial IR failure. This is because it occurs.

  The baking is held at a temperature of 850 to 1050 ° C. for 1 to 2 hours to be densified to a relative density of 95% or more. The firing temperature is 850 to 930 ° C. when the conductor material is mainly composed of Ag. Thus, the ceramic circuit board of the present invention can be manufactured.

  In the above manufacturing method, it is desirable that the difference in shrinkage start temperature between the insulating ceramic layer and the metal wiring layer is 300 ° C. or less. The reason for this is that by making the difference in shrinkage start temperature between the insulating ceramic layer and the metal wiring layer 300 ° C. or less, it is possible to prevent the occurrence of fine cracks due to mismatch of shrinkage behavior, resulting in a decrease in insulation resistance. It can prevent more effectively. In particular, in order to prevent a decrease in insulation resistance when the thickness of the insulating ceramic layer is 50 μm or less, it is desirable that the difference in shrinkage start temperature between the insulating ceramic layer and the metal wiring layer is 200 ° C. or less.

First, as the insulating ceramic _layer, 0.95MgTiO 3 and 80 wt% of the main component composition and -0.05CaTiO _3, 99% or more of _{B 2 O 3, Li 2 CO} 3, SiO 2, BaCO 3 powder Was mixed with 20% by mass in total to produce an insulating ceramic material having an average particle diameter of 1.0 μm and a shrinkage start temperature of 800 ° C.

  To this raw material powder, together with an organic binder, a dispersant and a plasticizer, a predetermined amount of toluene and isopropyl alcohol were prepared and kneaded to form a slurry, which was then tape-formed by a doctor blade method to produce a green sheet having a thickness of 60 μm. In addition, the thickness after baking of this green sheet was 50 micrometers.

Meanwhile, as a silver paste, Ag powder having an average particle diameter of 2.5 μm is composed of 70 mass% of SiO ₂ , 10 mass% of Al ₂ O _3, 10 mass% of CaO, and 10 mass% of B ₂ O _{3 with} respect to 100 mass parts. As shown in Table 1, the glass frit having the composition was changed to 3 to 7% by mass to produce a silver paste having shrinkage initiation temperatures of 500, 600, and 750 ° C.

  An electrode was formed by screen printing using the obtained green sheet and silver-based paste, 10 sheets of the green sheet printed with this electrode were stacked, cut into a predetermined size, and then fired using a tunnel furnace.

  In firing, the temperature increase rate in the temperature region (A) from room temperature to the firing shrinkage start temperature of the conductor material is 15 ° C./min, and the temperature range from the firing shrinkage start temperature of the conductor material to the shrinkage start temperature of the insulating ceramic material The heating rate of (B) was 7.5 ° C./min. Thereafter, according to the present invention, the temperature region (C) from the shrinkage start temperature to the firing temperature of the insulating ceramic material was fired under the conditions shown in Table 1.

The shrinkage start temperature of these samples was determined from TMA. The area where the content of the glass forming component continuously changed was determined from EPMA of the fracture surface of the sample. Specifically, the diffusion state from the metal wiring layer of Al which is a glass forming component in the silver-based paste was measured. Since all the samples in which the diffusion was observed had the content continuously changing in the Al diffusion region, the Al diffusion distance was measured as a region in which the content of the glass forming component was continuously changing. In addition, the humidity resistance reliability was measured by measuring the insulation resistance after 1000 hours in a state where a temperature of 85 ° C. and a humidity of 85% was applied with 15 V DC applied to the metal wiring layer. As for the initial IR characteristics, the initial insulation resistance (before charging) of the humidity resistance reliability evaluation sample was measured, and a resistance value of 10 ⁵ Ω or less was regarded as a defective product. In addition, the insulation resistance was 10 ⁸ Ω or less as a defective product.

  As is apparent from the results in Table 1, the content of the glass-forming component continuously changes over a thickness of 10% or more of the thickness of the insulating ceramic layer. Except for 3, 6 and 9, all of them were able to improve the initial IR failure, prevent the insulation resistance from being lowered, and improve the humidity resistance reliability.

It is a schematic sectional drawing of the ceramic circuit board of this invention. It is a schematic diagram for demonstrating the diffusion state of the metal wiring layer vicinity in the ceramic circuit board of this invention.

Explanation of symbols

A Ceramic circuit board 1 Insulating ceramic layer 2 Metal wiring layer 3 Via conductor

Claims (8)

A ceramic circuit board comprising: an insulating substrate formed by laminating a plurality of insulating ceramic layers; and a plurality of metal wiring layers disposed between the insulating ceramic layers of the insulating substrate, wherein the metal wiring layer includes metal particles. The glass forming component is diffused from the metal wiring layer to the insulating ceramic layer, and the content of the glass forming component is over 10% or more of the thickness of the insulating ceramic layer. A ceramic circuit board characterized by continuously changing. The ceramic circuit board according to claim 1, wherein the insulating ceramic layer has a thickness of 50 μm or less. The ceramic circuit board according to claim 1, wherein the metal wiring layer contains silver as a main component. The ceramic circuit board according to claim 1, wherein the insulating ceramic layer is made of a low-temperature fired ceramic that can be fired at 1050 ° C. or less. A method for producing a ceramic circuit board comprising a ceramic green sheet containing an insulating ceramic material and an organic binder, a conductive material comprising a metal powder and a glass powder applied to a wiring pattern, and then laminating and firing them. , The shrinkage start temperature of the insulating ceramic material is lower than the shrinkage start temperature of the conductor material, and the temperature range from the shrinkage start temperature of the insulating ceramic material to the firing temperature in the temperature raising process up to the firing temperature is 5.0. A method for producing a ceramic circuit board, wherein the temperature is raised at a rate of not more than ° C / min. The method for manufacturing a ceramic circuit board according to claim 1, wherein the firing temperature is 1000 ° C or lower. 6. The method of manufacturing a ceramic circuit board according to claim 5, wherein a difference in shrinkage start temperature between the conductor material and the insulating ceramic material is 300 [deg.] C. or less. 6. The method of manufacturing a ceramic circuit board according to claim 5, wherein the insulating ceramic material comprises a mixture of a glass component and an inorganic filler component.

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