JP2008186933A - Method for manufacturing laminated electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a highly reliable laminated electronic component which method suppresses the growth of conductor grains at a stage of baking to effectively prevent globing and electrode severance even if an internal electrode layer reduces in thickness, and improves a product crack occurrence rate. <P>SOLUTION: The manufacturing method is used to manufacture the laminated electronic component which has an element body composed of internal electrode layers and dielectric layers that are laminated alternately, and a pair of terminal electrodes formed on both ends of the element body. Paste containing a first conductive material mainly made of nickel and a second conductive material mainly made of rhenium (Re) at a given ratio is used as an electrode paste for forming electrode pattern films that are turned into the internal electrode layers by baking. A lamination made by alternately laminating green sheets that are turned into the dielectric layers by baking and electrode pattern films that are turned into the internal electrode layer by baking is subjected to defatting under temperatures of 850 to 1,000°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a multilayer electronic component such as a multilayer ceramic capacitor.

  A multilayer ceramic capacitor as an example of a multilayer electronic component includes an element body having a multilayer structure in which a plurality of dielectric layers and internal electrode layers are alternately arranged, and a pair of external terminal electrodes formed at both ends of the element body. It consists of.

  In order to manufacture this multilayer ceramic capacitor, first, a plurality of pre-fired dielectric layers and pre-fired internal electrode layers are alternately laminated in a necessary number to form a pre-fired element body, which is fired. That is, when manufacturing the multilayer ceramic capacitor, the pre-fired dielectric layer and the pre-fired internal electrode layer are fired simultaneously.

  Therefore, the conductive material contained in the internal electrode layer before firing has a melting point higher than the sintering temperature of the dielectric powder contained in the dielectric layer before firing, does not react with the dielectric powder, and the dielectric after firing. It is required not to diffuse into the layer. Conventionally, in order to satisfy these requirements, noble metals such as Pt and Pd are used as the conductive material contained in the internal electrode layer before firing. However, the precious metal has a disadvantage that it is expensive per se, and the resulting multilayer ceramic capacitor is expensive. Therefore, conventionally, the sintering temperature of the dielectric powder is lowered to 900 to 1100 ° C., and an Ag—Pd alloy is used as the conductive material included in the internal electrode layer before firing, or an inexpensive base metal such as Ni is used. .

  However, when Ni is used for the conductive material included in the internal electrode layer before firing, the following problems have occurred. That is, since Ni has a lower melting point than the dielectric powder contained in the dielectric layer before firing, when these are fired simultaneously, a large difference occurs between the sintering temperatures of the two. If there is a large difference in sintering temperature, sintering at a high temperature will cause cracking and peeling of the internal electrode layer, while sintering at a low temperature may cause firing failure of the dielectric powder.

  In addition, if the thickness of the internal electrode layer before firing is reduced in order to reduce the size and increase the capacity of the multilayer ceramic capacitor, Ni particles contained in the conductive material are caused by grain growth during firing in a reducing atmosphere. It sometimes spheroidized. And as a result, the interval between adjacent Ni particles that were connected before firing is widened to create vacancies at arbitrary locations, and as a result, it is difficult to continuously form the internal electrode layer after firing. turn into. When the internal electrode layers after firing are not continuous, there is a problem that the capacitance of the multilayer ceramic capacitor is lowered.

  On the other hand, in order to solve the above problem, the present applicant has proposed that the internal electrode layer is formed of an alloy of Ni and a noble metal such as Ru in the multilayer ceramic capacitor (patent). Reference 1). By constituting the internal electrode with such an alloy of Ni and a noble metal such as Ru, even when the thickness of the internal electrode layer is reduced, the grain growth of Ni particles in the firing stage is suppressed, and the spherical shape is reduced. And the electrode breakage can be effectively prevented, and the decrease in capacitance can be effectively suppressed.

  On the other hand, in recent years, various electronic devices have been miniaturized, and further reduction in size and increase in capacity are demanded for multilayer ceramic capacitors mounted inside electronic devices. In order to reduce the size and increase the capacity, for example, in Patent Document 1, if the thickness of the internal electrode layer is 1 μm or less and the number of laminated dielectric layers and internal electrode layers is increased, the reliability decreases. There was a new problem that would occur.

International Publication No. 2004/070748 Pamphlet

  The present invention has been made in view of such a situation, and the object thereof is to suppress the grain growth of the conductor particles in the firing stage, in particular, even when the thickness of the internal electrode layer is thinned, spheroidization, electrode breakage It is an object of the present invention to provide a method for manufacturing a highly reliable multilayer electronic component having an improved crack occurrence rate of products while effectively preventing the occurrence of cracks.

  In order to achieve the above object, the present inventors have affected the influence of the residual solvent and the residual binder contained in the green sheet serving as the dielectric layer after firing and the electrode pattern film serving as the internal electrode layer after firing during firing. Attention has been made and it has been found that the above object can be achieved by effectively removing the residual solvent and residual binder before firing, and the present invention has been completed.

That is, according to the present invention, there is provided a multilayer electronic component having an element body in which internal electrode layers and dielectric layers are alternately laminated, and a pair of terminal electrodes formed at both ends of the element body. A method of manufacturing comprising:
Forming a green sheet to be the dielectric layer after firing;
Using an electrode paste to form an electrode pattern film that becomes the internal electrode layer after firing;
Alternately stacking the green sheet and the electrode pattern film to obtain a laminate;
A binder removal step for degreasing the laminate;
Forming a pair of terminal electrodes at both ends of the laminate that has been degreased;
Firing the laminate on which the terminal electrode is formed, and
The temperature of the degreasing process in the binder removal step is 850 to 1000 ° C., and
As an electrode paste for forming the electrode pattern film,
A first conductive material mainly composed of nickel;
A second conductive material mainly composed of rhenium (Re),
When the total of the first conductive material and the second conductive material is 100% by weight, these ratios are:
First conductive material: 80 wt% or more, less than 100 wt%,
Second conductive material: more than 0% by weight and 20% by weight or less,
A method for manufacturing a multilayer electronic component using the electrode paste is provided.

  In the present invention, it is preferable that after the binder removal step, the end surface of the laminated body is polished and the terminal electrode is formed after the end surface is polished.

  Preferably, the conductive material constituting the terminal electrode is Ni or a Ni alloy. In the case of using a Ni alloy, the amount of Ni in the alloy is preferably 95% by weight or more.

  Preferably, the internal electrode layer has a thickness of 1 μm or less, more preferably 0.6 μm or less. By reducing the thickness of the internal electrode layer, the multilayer electronic component can be reduced in size and capacity.

  As the first conductive material and the second conductive material contained in the electrode paste, for example, it may be contained in the paste as an alloy powder composed of the first conductive material and the second conductive material, or separately. You may mix and use powder, ie, 1st electrically conductive material powder, and 2nd electrically conductive material powder.

  The multilayer electronic component according to the present invention is not particularly limited, and examples thereof include multilayer ceramic capacitors, piezoelectric elements, chip inductors, chip varistors, chip thermistors, chip resistors, and other surface mount (SMD) chip electronic components. .

  According to the present invention, the electrode pattern film that becomes the internal electrode layer after firing includes an electrode paste containing a first conductive material containing Ni as a main component and a second conductive material containing rhenium (Re) as a main component. It forms using. Therefore, even when the thickness of the internal electrode layer is reduced, it is possible to suppress the grain growth of the conductive particles at the firing stage, which has been a problem when a base metal such as Ni is used alone. In addition, it is possible to effectively prevent spheroidization and electrode breakage, and to effectively prevent a decrease in capacitance.

  In addition, in the present invention, the laminated body before firing is removed to remove the residual solvent and binder contained in the green sheet that becomes the dielectric layer after firing and the electrode pattern film that becomes the internal electrode layer after firing. The binder treatment is performed at a relatively high temperature of 850 to 1000 ° C. Therefore, the amount of residual solvent and residual binder after the binder removal treatment can be reduced. As a result, when firing is performed after the binder removal, the residual solvent and residual carbon contained in the residual binder are oxidized. By using carbon dioxide gas, it is possible to effectively prevent a problem that bubbles are generated in the element and thereby cracks are generated. That is, the crack generation rate can be reduced, and a highly reliable multilayer electronic component can be provided.

  In the present invention, the electrode pattern film that becomes the internal electrode layer after firing is formed using the first conductive material and the second conductive material described above, and these ratios are within a predetermined range. The oxidation resistance of the film can be improved. As a result, even when the temperature of the binder removal treatment is set to a relatively high temperature of 850 to 1000 ° C., the oxidation of the internal electrode layer can be effectively prevented, Therefore, the binder removal process at such a temperature is possible.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.
2 (A) to 2 (C) are main part cross-sectional views showing a transfer method of the internal electrode layer film,
FIG. 3A to FIG. 3C are cross-sectional views of relevant parts showing a step subsequent to FIG.

  First, an overall configuration of a multilayer ceramic capacitor will be described as an embodiment of the multilayer electronic component according to the present invention.

  As shown in FIG. 1, the multilayer ceramic capacitor 2 according to the present embodiment includes a capacitor body (element body) 4, a first terminal electrode 6, and a second terminal electrode 8. The capacitor body 4 includes dielectric layers 10 and internal electrode layers 12, and the internal electrode layers 12 are alternately stacked between the dielectric layers 10. One internal electrode layer 12 that is alternately stacked is electrically connected to the inside of the first terminal electrode 6 that is formed outside one end of the capacitor body 4. The other internal electrode layers 12 stacked alternately are electrically connected to the inside of the second terminal electrode 8 formed outside the other end of the capacitor body 4.

  The internal electrode layer 12 includes, as a conductive material, a first conductive material whose main component is nickel as a base metal and a second conductive material whose main component is rhenium (Re). In the internal electrode layer 12, it is considered that the first conductive material and the second conductive material exist in the form of these alloys.

  The content ratio of the first conductive material in the internal electrode layer 12 is 80 wt% or more and less than 100 wt% when the total of the first conductive material and the second conductive material is 100 wt%, preferably, 90% by weight or more and 95% by weight or less. The content ratio of the second conductive material is more than 0% by weight and 20% by weight or less, preferably 5% by weight or more and 20% by weight or less. If the second conductive material is not included, the end oxidation of the internal electrode occurs during the binder removal process, resulting in a large capacity variation of the obtained multilayer ceramic capacitor, and the reliability as a product is lowered. On the other hand, if the content ratio of the second conductive material is too large, inconveniences such as an increase in dielectric loss and resistivity tend to occur.

  As will be described in detail later, the internal electrode layer 12 is formed by transferring the electrode pattern film 12a to the ceramic green sheet 10a as shown in FIGS. The internal electrode layer 12 is made of the same material as that of the electrode pattern film 12a, but its thickness is larger than that of the electrode pattern film 12a by the amount of horizontal contraction caused by firing. The thickness of the internal electrode layer 12 is preferably 1 μm or less, more preferably 0.6 μm or less, and still more preferably 0.3 μm or less. By reducing the thickness of the internal electrode layer, the multilayer ceramic capacitor 2 can be reduced in size and capacity. In particular, in this embodiment, the internal electrode layer 12 is configured to contain the first conductive material and the second conductive material described above at a predetermined ratio, so that the growth of conductive particles in the firing stage is suppressed. As a result, the internal electrode layer can be thinned in this way.

The material of the dielectric layer 10 is not particularly limited, and is made of a dielectric material such as calcium titanate, strontium titanate and / or barium titanate. In addition to these dielectric materials, various subcomponents may be further added as necessary. For example, a glass component mainly composed of SiO ₂ , B ₂ O ₃ , Li ₂ O ₃ or the like can be cited as an auxiliary component for reducing the firing temperature. In addition, as subcomponents for adjusting reduction resistance and temperature characteristics, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc. Examples thereof include oxides containing rare earth elements and oxides containing transition metals such as Sc, Ti, V, Cr, Mn, Fe, Co, and Ni.

  The thickness of the dielectric layer 10 is not particularly limited, but is generally several μm to several hundred μm. In particular, in this embodiment, the thickness is preferably 5 μm or less, more preferably 3 μm or less.

  As the conductive material constituting the terminal electrodes 6 and 8, Ni or Ni alloy is preferably used in the present embodiment. In the case of using a Ni alloy, the amount of Ni in the alloy is preferably 95% by weight or more. The thickness of the terminal electrodes 6 and 8 is not particularly limited, but is usually about 10 to 50 μm. The shape of these conductive materials is not particularly limited, and may be spherical, scale-like, or a mixture of these shapes.

  The shape and size of the multilayer ceramic capacitor 2 may be appropriately determined according to the purpose and application. When the multilayer ceramic capacitor 2 has a rectangular parallelepiped shape, it is usually about vertical (0.6 to 5.6 mm) × horizontal (0.3 to 5.0 mm) × thickness (0.1 to 3.2 mm).

Next, an example of a method for manufacturing the multilayer ceramic capacitor 2 will be described.
First, a dielectric paste is prepared in order to manufacture a ceramic green sheet that will form the dielectric layer 10 shown in FIG. 1 after firing.
The dielectric paste is usually composed of an organic solvent-based paste obtained by kneading a dielectric material and an organic vehicle, or an aqueous paste.

  As the dielectric material, various compounds to be complex oxides and oxides, for example, carbonates, nitrates, hydroxides, organometallic compounds, and the like are appropriately selected and used by mixing. The dielectric material is usually used as a powder having an average particle size of about 0.1 to 3.0 μm. In order to form a very thin green sheet, it is desirable to use a powder finer than the thickness of the green sheet.

  As the dielectric material, for example, a part or all of the material constituting the dielectric layer 10 is wet-mixed by a ball mill or the like, then dried by a spray dryer or the like, and then calcined, You may use as a baking raw material. Calcination is usually performed at a temperature of 800 to 1300 ° C. for about 2 to 10 hours. The calcined raw material may be pulverized with a jet mill or a ball mill until a predetermined particle size is obtained.

  An organic vehicle is obtained by dissolving a binder in an organic solvent. The binder used for the organic vehicle is not particularly limited, and for example, abitienic acid resin, polyvinyl butyral, ethyl cellulose, acrylic resin, and the like are used. Of these, butyral resins such as polyvinyl butyral are preferable.

  Further, the organic solvent used in the organic vehicle is not particularly limited, and organic solvents such as ethanol, terpineol, butyl carbitol, acetone, toluene, kerosene, and ethyl acetate are used. Further, the vehicle in the aqueous paste is obtained by dissolving a water-soluble binder in water. The water-soluble binder is not particularly limited, and polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, water-soluble acrylic resin, emulsion and the like are used. The content of each component in the dielectric paste is not particularly limited, and the usual content, for example, the dielectric material is about 30 to 80% by weight, the binder is about 2 to 5% by weight, and the solvent (or water) is 20%. What is necessary is just about 70 weight%.

The dielectric paste may contain additives selected from various dispersants, plasticizers, dielectrics, glass frit, insulators and the like as required.
For example, examples of the plasticizer include phthalic acid ester, adipic acid, phosphoric acid ester, and glycols. Examples of the dispersant include a maleic acid dispersant, a polyethylene glycol dispersant, and an allyl ether copolymer dispersant. The content of the plasticizer is about 0.1 to 5% by weight. If the amount of the plasticizer is too small, the green sheet tends to become brittle. If the amount is too large, the plasticizer oozes out and is difficult to handle. Moreover, content of a dispersing agent is about 0.1 to 5 weight%.

  The dielectric paste can be prepared by using a dielectric material, an organic vehicle, and various additives added as necessary using a basket mill, a ball mill, a bead mill, or the like.

  Next, using the above-mentioned dielectric paste, as shown in FIG. 3A, the thickness is preferably about 0.5 to 20 μm, more preferably about 1 to 10 μm on the carrier sheet 30 as the second support sheet. Thus, the green sheet 10a is formed. The green sheet can be formed by, for example, a coating method using a doctor blade, a lip coater, a die coater, a reverse coater, or the like. The green sheet 10 a is dried after being formed on the carrier sheet 30. The drying temperature of the green sheet 10a is preferably 50 to 100 ° C., and the drying time is preferably 1 to 5 minutes.

  Next, separately from the carrier sheet 30, as shown in FIG. 2A, a carrier sheet 20 as a first support sheet is prepared, and a release layer 22 is formed thereon. Next, an electrode pattern film 12 a that will form the internal electrode layer 12 after firing is formed in a predetermined pattern on the surface of the release layer 22.

  The thickness of the formed electrode pattern film 12a is preferably about 0.1 to 1 μm, more preferably about 0.1 to 0.5 μm. The electrode pattern film 12a may be composed of a single layer, or may be composed of two or more layers having different compositions.

  The electrode pattern film 12a is formed by a printing method such as screen printing using an electrode paste, for example. When the electrode pattern film 12a is formed on the surface of the release layer 22 by a screen printing method, which is one type of printing method, the following is performed.

  First, an electrode paste for forming the electrode pattern film 12a is prepared. The electrode paste can be manufactured by kneading the first conductive material raw material and the second conductive material raw material together with an organic vehicle into a paste. Examples of the first conductive material raw material include Ni powder, various oxides that become Ni after firing, organometallic compounds, or resinates. Similarly, as the second conductive material raw material, a powder of Re element or an alloy containing Re as a main component, and various oxides, organometallic compounds, or resinates that become these metals after firing can be used. .

  The first conductive material raw material and the second conductive material raw material may be used in the form of separate raw material powders, or an alloy powder obtained by previously alloying the first conductive material and the second conductive material is used. In this embodiment, it is preferable to use an alloy powder. As such an alloy powder composed of the first conductive material and the second conductive material, a powder having a desired composition ratio may be appropriately used.

  As shown in FIG. 2A, the obtained electrode paste is formed in a predetermined pattern on the surface of the release layer 22, for example, by screen printing, thereby forming an electrode pattern film 12a having a predetermined pattern.

  In the present embodiment, the blank pattern layer 14 having substantially the same thickness as the electrode pattern film 12a is formed on the portion of the release layer 22 where the electrode pattern film 12a is not formed after or before the electrode pattern film 12a is formed. Form. The blank pattern layer 14 is made of the same material as that of the green sheet 10a. The blank pattern layer 14 may be formed by a printing method similarly to the electrode pattern film 12a. By forming the blank pattern layer 14, the surface level difference due to the electrode pattern film 12a having a predetermined pattern is eliminated, and the inconvenience at the time of stacking or after firing due to the level difference can be eliminated.

  Next, separately from the carrier sheets 20 and 30, the adhesive layer transfer sheet in which the adhesive layer 28 is formed on the surface of the carrier sheet 26 as the third support sheet as shown in FIG. prepare. The carrier sheet 26 is composed of a sheet similar to the carrier sheets 20 and 30.

  In this embodiment, a transfer method is employed in order to form an adhesive layer on the surface of the electrode pattern film 12a shown in FIG. That is, as shown in FIG. 2 (B), the adhesive layer 28 of the carrier sheet 26 is pressed against the surface of the electrode pattern film 12a, heated and pressurized, and then the carrier sheet 26 is peeled off. As shown, the adhesive layer 28 is transferred to the surface of the electrode pattern film 12a.

  The heating temperature at that time is preferably 40 to 100 ° C., and the pressure is preferably 0.2 to 15 MPa. The pressurization may be a pressurization or a calender roll, but is preferably performed by a pair of rolls.

  Thereafter, the electrode pattern film 12a and the blank pattern layer 14 are transferred to the surface of the green sheet 10a formed on the surface of the carrier sheet 30 shown in FIG. In the present embodiment, as shown in FIG. 3B, the electrode pattern film 12a and the blank pattern layer 14 of the carrier sheet 20 are pressed against the surface of the green sheet 10a together with the carrier sheet 20 through the adhesive layer 28, and heated. As shown in FIG. 3C, the electrode pattern film 12a and the blank pattern layer 14 are transferred to the surface of the green sheet 10a through the adhesive layer 28 by applying pressure. However, since the carrier sheet 30 on the green sheet 10a side is peeled off, the green sheet 10a is transferred to the electrode pattern film 12a and the blank pattern layer 14 through the adhesive layer 28 when viewed from the green sheet 10a side.

  The heating and pressurization at the time of transfer may be pressurization / heating with a press or pressurization / heating with a calender roll, but is preferably performed with a pair of rolls. The heating temperature and pressure are the same as when the adhesive layer 28 is transferred.

  2A to 3C, the electrode pattern film 12a and the blank pattern layer 14 having a predetermined pattern are formed on the single green sheet 10a. Using this, a laminated body in which a large number of electrode pattern films 12a and blank pattern layers 14 and green sheets 10a are alternately laminated is obtained.

  Thereafter, the final pressure is applied to the laminate, and then the carrier sheet 20 is peeled off. The pressure at the time of final pressurization is preferably 10 to 200 MPa. Moreover, 40-100 degreeC is preferable for heating temperature.

  Thereafter, the laminate is cut into a predetermined size to form a green chip. The green chip is first subjected to a binder removal process (degreasing process).

  In the present embodiment, the binder removal treatment is performed at a relatively high temperature, ie, a holding temperature (degreasing treatment temperature) of 850 to 1000 ° C., preferably 900 to 950 ° C. In the present embodiment, since the electrode pattern film 12a, which will constitute the internal electrode layer 12 after firing, is composed of the first conductive material and the second conductive material described above, such a relatively high temperature. The degreasing process can be performed at That is, since the electrode pattern film 12a is excellent in oxidation resistance, the internal electrode layer can be effectively prevented from being oxidized even when the degreasing treatment is performed at a relatively high temperature. Thus, the degreasing treatment can be sufficiently performed, and the amount of residual solvent and residual binder (residual carbon amount) in the chip during subsequent firing can be reduced. Therefore, as a result, the residual carbon contained in the residual solvent and the residual binder is oxidized at the time of firing to become carbon dioxide gas, thereby generating bubbles in the element, thereby causing cracks. Can be effectively prevented.

The binder removal treatment conditions other than the above are preferably the following conditions.
Temperature increase rate: 5 to 300 ° C./hour, particularly 10 to 60 ° C./hour,
Retention time: 0.5 to 20 hours, especially 1 to 10 hours,
Atmosphere: Inert gas atmosphere such as humidified N ₂ atmosphere.

  Next, the end face of the chip subjected to the binder removal processing is polished. Examples of the end face polishing include barrel polishing and sand blasting. By performing end face polishing, the corner portion can be formed in the chip after the binder removal treatment, and the electrode end portion (end portion of the electrode pattern film) can be exposed to the chip surface. By exposing the electrode end portions, the electrical connection between the end portions of the electrode pattern film that becomes the internal electrode layer 12 after firing and the terminal electrodes 6 and 8 described later can be improved.

  Next, a terminal electrode paste for forming the terminal electrodes 6 and 8 is applied to the end-polished chip. Ni or Ni alloy is used as the conductive material to be included in the terminal electrode paste. The terminal electrode paste may be prepared in the same manner as the above electrode paste. Moreover, after apply | coating the paste for terminal electrodes, in order to remove the solvent contained in the paste for terminal electrodes, you may perform a drying process as needed.

  Next, firing and annealing (heat treatment) are performed on the chip coated with the terminal electrode paste.

Firing is preferably performed under the following conditions.
Temperature rising rate: 50 to 1000 ° C./hour, particularly 200 to 300 ° C./hour,
Holding temperature: 1100-1300 ° C., in particular 1150-1250 ° C.
Retention time: 0.5-8 hours, especially 1-3 hours,
Cooling rate: 50 to 500 ° C./hour, particularly 200 to 300 ° C./hour,
Atmospheric gas: A mixed gas of humidified N ₂ and H ₂ or the like.

However, the oxygen partial pressure in the air atmosphere during firing is preferably 1 Pa or less, particularly 10 ⁻² to 10 ⁻⁸ Pa. If the above range is exceeded, the internal electrode layer tends to oxidize, and if the oxygen partial pressure is too low, the electrode material of the internal electrode layer tends to abnormally sinter and tend to break.

Annealing (heat treatment) is a process for re-oxidizing the dielectric layer, whereby the accelerated lifetime of the insulation resistance (IR) can be remarkably increased, and the reliability is improved.
The annealing (heat treatment) after such firing is preferably performed at a holding temperature or a maximum temperature of preferably 800 ° C. or higher. If the holding temperature or maximum temperature during heat treatment is less than the above range, the dielectric material is insufficiently oxidized and the insulation resistance life tends to be shortened. In addition to a decrease, it tends to react with the dielectric substrate and shorten its lifetime. The oxygen partial pressure during the heat treatment is higher than the reducing atmosphere during firing, and is preferably 10 ⁻³ Pa to 10 Pa, more preferably 10 ⁻² Pa to 10 Pa. If it is less than the above range, reoxidation of the dielectric layer 2 is difficult, and if it exceeds the above range, the internal electrode layer 12 tends to be oxidized.

In this embodiment, since the step of forming a terminal electrode on the chip end face is employed before firing and annealing, firing and annealing can be performed in a state where the internal electrode layer is not exposed. it can. Therefore, firing and annealing can be performed at a relatively high temperature or a relatively high oxygen partial pressure. In particular, by performing annealing at a relatively high temperature and high oxygen partial pressure, the insulation resistance (IR) and the accelerated life of the insulation resistance (IR) can be improved, and the reliability can be further improved. Improvements can be made.
In the present embodiment, it is preferable to perform the firing and the annealing process continuously. In this case, it is preferable to raise the temperature to the holding temperature at the time of baking, perform baking, then cool, and perform the heat treatment by changing the atmosphere when the heat treatment holding temperature is reached.

In the case where the firing and the annealing treatment are continuously performed, the following annealing conditions other than the above are preferable.
Retention time: 0-6 hours, especially 0.5-5 hours,
Cooling rate: 50 to 500 ° C./hour, in particular 100 to 300 ° C./hour,
Atmospheric gas: humidified N ₂ gas or the like.

Note that to wet the N ₂ gas may be used, for example, a wetter or the like. In this case, the water temperature is preferably about 0 to 75 ° C.

  Then, the multilayer ceramic capacitor shown in FIG. 1 can be obtained by performing Ni plating or Sn plating on the terminal electrode as necessary. The multilayer ceramic capacitor of the present embodiment thus obtained is mounted on a printed circuit board by soldering or the like and used for various electronic devices.

As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, In the range which does not deviate from the summary of this invention, it can implement with a various aspect.
For example, the present invention is not limited to a multilayer ceramic capacitor and can be applied to other electronic components.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

Example 1
Preparation of Dielectric Paste First, BaTiO ₃ powder (BT-02 / Sakai Chemical Industry Co., Ltd.), MgCO ₃ , MnCO ₃ , (Ba _0.6 Ca _0.4 ) SiO ₃ and rare earth oxide (Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ , Y ₂ O ₃ ) A dielectric material was obtained by wet mixing with a ball mill for 16 hours and drying. These raw material powders had an average particle size of 0.1 to 1 μm. (Ba _0.6 Ca _0.4 ) SiO ₃ was obtained by wet-mixing BaCO ₃ , CaCO ₃ and SiO ₂ with a ball mill for 16 hours, and firing in air at 1150 ° C. after drying using a ball mill. It was produced by wet milling for a period of time.

  In order to paste the obtained dielectric material, an organic vehicle was added to the dielectric material and mixed by a ball mill to obtain a dielectric paste. The organic vehicle is based on 100 parts by weight of the dielectric material, polyvinyl butyral: 6 parts by weight as a binder, bis (2-ethylhexyl) phthalate (DOP): 3 parts by weight, ethyl acetate: 55 parts by weight, toluene: The blending ratio is 10 parts by weight and 0.5 parts by weight of paraffin as a release agent.

Preparation of electrode paste Ni / Re alloy powder was prepared as a conductive material for forming the electrode paste. Next, BaTiO ₃ : 20 parts by weight, organic vehicle (ethyl cellulose: terpineol = 5: 200 (weight ratio)): 205 parts by weight are added to Ni / Re alloy powder: 100 parts by weight, and kneaded with three rolls. The electrode paste was prepared by dispersing.

  In this example, as shown in Table 1, a plurality of alloy powders having different Ni / Re ratios were prepared, and a plurality of electrode pastes using conductive materials having different Ni / Re ratios were prepared.

Preparation of Terminal Electrode Paste Ni powder was prepared as a conductive material for forming the terminal electrode paste. Next, 20 parts by weight of BaTiO ₃ , 5 parts by weight of ethyl cellulose as an organic binder, and 15 parts by weight of terpineol as a solvent are added to 100 parts by weight of Ni powder, and kneaded and dispersed with a three-roll. Thus, a terminal electrode paste was prepared.

Formation of Green Sheet Using the dielectric paste obtained above, a 1.0 μm thick green sheet was formed on a PET film (second support sheet) using a wire bar coater.

Formation of Electrode Pattern Film and Blank Pattern Layer First, the dielectric paste prepared above was diluted 2 times by weight with ethanol / toluene (55/10) to obtain a release layer paste. Then, this release layer paste was applied and dried on another PET film (first support sheet) with a wire bar coater to form a release layer having a thickness of 0.3 μm.

  Next, an electrode pattern film was formed on the release layer by printing the electrode paste prepared above in a predetermined pattern with a screen printer and drying it. Note that the thickness of the electrode pattern film after drying was 0.7 μm.

  Next, the blank pattern layer was formed by printing the dielectric paste prepared above on a portion of the release layer where the electrode pattern film was not formed, using a screen printer and drying. For the printing of the blank pattern, a screen plate making which is a pattern complementary to the pattern used when printing the electrode pattern film was used. The blank pattern was formed so that the film thickness at the time of drying was the same as that of the internal electrode layer.

Formation of adhesive layer Except for not containing dielectric particles and release agent, the paste obtained in the same manner as the dielectric paste prepared above was diluted 4 times by weight with toluene, and this was used for adhesive layer A paste was used. Then, this adhesive layer paste is coated and dried by a wire bar coater on another PET film (third support sheet) whose surface has been subjected to a release treatment with a silicone-based resin, and has a thickness of 0.2 μm. Layer 28 was formed.

Formation of Green Chip First, the adhesive layer 28 was transferred to the surface of the internal electrode layer film 12a by the method shown in FIG. At the time of transfer, a pair of rolls were used, the pressure was 0.1 MPa, and the temperature was 80 ° C.

  Next, the electrode pattern film 12a was adhered (transferred) to the surface of the green sheet 10a through the adhesive layer 28 by the method shown in FIG. At the time of transfer, a pair of rolls were used, the pressure was 0.1 MPa, and the temperature was 80 ° C.

  Next, the electrode pattern film 12a and the green sheet 10a were laminated one after another, and finally, a green chip on which 400 layers of the electrode pattern film 12a were laminated was obtained. The lamination conditions were a pressure of 50 MPa and a temperature of 120 ° C.

Debinding treatment (degreasing treatment) was performed on the obtained green chip under the following conditions for binder removal , barrel polishing, terminal electrode formation, firing and annealing .
Temperature increase rate: 60 ° C./hour,
Holding temperature: 950 ° C.
Retention time: 1 hour
Cooling rate: 60 ° C./hour,
Atmospheric gas: humidified N ₂ gas,
I went there. As will be described later, the amount of residual carbon was measured using a part of the chips subjected to the binder removal treatment.

  Next, barrel polishing was performed on the chip subjected to the binder removal treatment. Then, the terminal electrode paste was transferred to the exposed end surface of the electrode end of the chip subjected to barrel polishing, and drying was performed to remove the solvent.

  Next, firing and annealing (heat treatment) were performed on the chip on which the terminal electrode was formed under the following conditions.

That is, firing is
Temperature increase rate: 100 ° C / hour,
Holding temperature: 1260 ° C
Retention time: 2 hours
Cooling rate: 100 ° C./hour,
Atmosphere gas: humidified mixed gas of N ₂ and H ₂ ,
Oxygen partial pressure: 10 ^-4 Pa
I went there.

Annealing (heat treatment)
Holding temperature: 800 ° C.
Retention time: 0.5 hours
Cooling rate: 100 ° C./hour,
Atmospheric gas: humidified N ₂ gas,
Oxygen partial pressure: 10 ⁻¹ Pa,
I went there.
In this example, after holding at the firing holding temperature (1260 ° C.) for 2 hours, cooling to the annealing (heat treatment) holding temperature (800 ° C.) at a cooling rate of 100 ° C./hour, Annealing (heat treatment) was performed by changing the oxygen partial pressure.
Further, a wetter with a water temperature of 0 to 75 ° C. was used for humidifying the atmospheric gas in firing and annealing (heat treatment).

  As described above, a sample of the multilayer ceramic capacitor having the configuration shown in FIG. 1 was obtained. The size of each sample thus obtained is 2.0 mm × 1.2 mm × 0.8 mm, the number of dielectric layers sandwiched between internal electrode layers is 400, and the thickness is 0.7 μm. there were. In this example, a Ni / Re alloy was used as the conductive material for forming the internal electrode layer, and a plurality of samples having different ratios (weight ratios) of Ni and Re were prepared as shown in Table 1. .

  About each obtained sample, each evaluation of residual carbon amount, capacity | capacitance variation, dielectric loss tan-delta, edge part oxidation rate, and crack generation rate was performed by the method shown below.

Residual carbon amount The chip after the binder removal step was pulverized, and the amount of CO ₂ generated by the combustion-infrared absorption method (CS-600 manufactured by LECO) was measured in an oxygen stream. The amount was measured. The results are shown in Table 1.

Capacitance variation First, the capacitance of each capacitor sample was measured using a digital LCR meter (4284A manufactured by YHP) at a reference temperature of 25 ° C. under the conditions of a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms. The capacitance was measured for 50 samples, and the standard deviation and the average value using the measurement results of the 50 samples as samples were obtained. Then, the variation in capacity was evaluated by obtaining the coefficient of variation (%) by dividing the standard deviation calculated from the measurement result by the average value. It can be evaluated that the smaller the coefficient of variation (%), the smaller the capacity variation. The results are shown in Table 1.

Dielectric loss tan δ
The dielectric loss tan δ was measured using a digital LCR meter (HP 4284A manufactured by HP) at a reference temperature of 25 ° C. and a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms with respect to the obtained capacitor sample.

For the obtained capacitor sample, the element map data near the interface between the terminal electrode and the internal electrode layer was collected using an electron probe microanalyzer (JXA8500F type FE-EPMA manufactured by JEOL Ltd.). It was. The measurement is performed on 50 internal electrode layers. As a result of the measurement, the one where the presence of oxygen atoms can be confirmed is defined as “end oxidation”, and the generation rate of end oxidation is obtained. ). The results are shown in Table 1.

About the capacitor | condenser sample which the crack generation rate was obtained, the external appearance inspection by the microscope was performed and the presence or absence of the generation | occurrence | production of a crack was measured. The measurement was performed on 200,000 samples, and the ratio of the cracked samples in 200,000 samples was obtained, and this was defined as the crack occurrence rate (ppm). The results are shown in Table 1.

表１中、試料番号１は、内部電極層を形成する導電材として、Ｎｉ／Ｒｅ合金の代わりに、Ｎｉを用いた。

In Table 1, Sample No. 1 used Ni instead of the Ni / Re alloy as the conductive material forming the internal electrode layer.

Evaluation 1
From Table 1, as a conductive material for forming the internal electrode layer, Ni (first conductive material) and Re (second conductive material) are set to a predetermined ratio of the present invention, and the binder removal treatment is performed at 950 ° C. It can be confirmed that the amount of residual carbon in the chip after the binder removal process can be reduced while keeping the variation, dielectric loss, and edge oxidation rate low, thereby reducing the crack generation rate.

  On the other hand, in the sample number 1 using Ni instead of the Ni / Re alloy as the conductive material for forming the internal electrode layer, the end portion oxidation rate was increased and the capacity variation was increased. In Sample No. 1, it is considered that end oxidation occurred mainly during the binder removal treatment. Further, from the result of sample number 7, it can be confirmed that when the ratio of Re (second conductive material) in the internal electrode layer is too large, the dielectric loss is deteriorated.

Example 2
A capacitor sample was prepared and evaluated in the same manner as Sample No. 3 in Example 1 except that the holding temperature (degreasing temperature) during the binder removal treatment was changed as shown in Table 1. The results are shown in Table 2.

表２中、試料番号１６は、実施例１の試料番号３と同じサンプルである。

In Table 2, sample number 16 is the same sample as sample number 3 of Example 1.

Evaluation 2
From Table 2, even when Ni (first conductive material) and Re (second conductive material) are set to a predetermined ratio of the present invention and the binder removal treatment is changed in the range of 850 to 1000 ° C., Example 1 and Similarly, it can be confirmed that the amount of residual carbon in the chip after the binder removal process can be reduced while keeping the capacity variation, the dielectric loss, and the edge oxidation rate low, thereby reducing the crack generation rate.

  On the other hand, when the binder removal process was performed at a temperature of 800 ° C. or less, the amount of residual carbon in the chip after the binder removal process increased, resulting in an increased crack generation rate. Further, when the binder removal treatment was performed at 1050 ° C., the end portion oxidation rate was increased, resulting in increased capacity variation.

Example 3
A capacitor sample was produced in the same manner as Sample No. 3 in Example 1 except that the thickness of the internal electrode layer after firing was changed as shown in Table 1, and was similarly evaluated. The results are shown in Table 3.

Comparative Example 1
A capacitor sample was prepared and evaluated in the same manner as Sample No. 1 in Example 1 except that the thickness of the internal electrode layer after firing was 0.9 μm. The results are shown in Table 3.

Comparative Example 2
A capacitor sample was prepared and evaluated in the same manner as Sample No. 1 in Example 1 except that the holding temperature (degreasing temperature) in the debinding process was 600 ° C. The results are shown in Table 3.

表３中、試料番号２４，２５は、内部電極層を形成する導電材として、Ｎｉ／Ｒｅ合金の代わりに、Ｎｉを用いた。

In Table 3, sample numbers 24 and 25 used Ni instead of the Ni / Re alloy as the conductive material for forming the internal electrode layer.

Evaluation 3
From the results of sample numbers 21 to 23 in Table 3, it can be confirmed that the same results are obtained even when the internal electrode layer thickness is changed as shown in Table 3.

  On the other hand, in the sample number 24 using Ni instead of the Ni / Re alloy as the conductive material for forming the internal electrode layer, even when the internal electrode layer thickness is relatively thick as 0.9 μm, the same applies. As a result, the edge oxidation rate increased and the capacity variation increased. In addition, in Sample No. 25 in which Ni was used instead of the Ni / Re alloy as a conductive material for forming the internal electrode layer and the binder removal treatment was performed at 600 ° C., the end portion oxidation rate was high, resulting in capacitance variation. As a result, the amount of residual carbon in the chip after the binder removal process increased and the crack generation rate deteriorated.

FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. 2 (A) to 2 (C) are cross-sectional views showing the main part of the method for transferring the internal electrode layer film. FIG. 3A to FIG. 3C are cross-sectional views of relevant parts showing a step subsequent to FIG.

Explanation of symbols

2 ... Multilayer ceramic capacitor 4 ... Capacitor body 6, 8 ... Terminal electrode 10 ... Dielectric layer 10a ... Green sheet 12 ... Internal electrode layer 12a ... Electrode pattern film 14 ... Blank pattern layer 20 ... Carrier sheet (first support sheet)
22 ... Release layer 26 ... Carrier sheet (third support sheet)
28 ... Adhesive layer 30 ... Carrier sheet (second support sheet)

Claims (4)

A method of manufacturing a multilayer electronic component having an element body in which internal electrode layers and dielectric layers are alternately laminated, and a pair of terminal electrodes formed at both ends of the element body,
Forming a green sheet to be the dielectric layer after firing;
Using an electrode paste to form an electrode pattern film that becomes the internal electrode layer after firing;
Alternately stacking the green sheet and the electrode pattern film to obtain a laminate;
A binder removal step for degreasing the laminate;
Forming a pair of terminal electrodes at both ends of the laminate that has been degreased;
Firing the laminate on which the terminal electrode is formed, and
The temperature of the degreasing process in the binder removal step is 850 to 1000 ° C., and
As an electrode paste for forming the electrode pattern film,
A first conductive material mainly composed of nickel;
A second conductive material mainly composed of rhenium (Re),
When the total of the first conductive material and the second conductive material is 100% by weight, these ratios are:
First conductive material: 80 wt% or more, less than 100 wt%,
Second conductive material: more than 0% by weight and 20% by weight or less,
A method for manufacturing a multilayer electronic component using the electrode paste.   2. The method for manufacturing a multilayer electronic component according to claim 1, wherein after the binder removal step, the end surface of the multilayer body is polished, and the terminal electrode is formed after the end surface is polished.   The method for manufacturing a multilayer electronic component according to claim 1, wherein the conductive material constituting the terminal electrode is Ni or a Ni alloy.   The method for manufacturing a multilayer electronic component according to claim 1, wherein the internal electrode layer has a thickness of 1 μm or less.

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