JP4560765B2 - Manufacturing method of multilayer electronic component - Google Patents

Description

  The present invention relates to a method for manufacturing a multilayer electronic component, and more particularly to a method for manufacturing a multilayer electronic component for manufacturing a multilayer electronic component such as a multilayer inductor having an internal conductor inside a ceramic body.

  In a multilayer ceramic electronic component, a conductive pattern is usually formed by screen-printing a conductive paste for internal conductors on the surface of a thin ceramic sheet, and a predetermined number of ceramic sheets on which such a conductive pattern is formed are laminated. After the laminated body is formed, the laminated body is subjected to a firing treatment, and then an external conductor is formed.

  In a multilayer ceramic electronic component, the coefficient of thermal expansion of the conductive material and the ceramic material that make up the inner conductor are different, and the shrinkage behavior is different. Tensile stress is generated and structural defects such as delamination can occur. In addition, when ferrite is used as the ceramic material, the impedance and inductance are reduced, and the electrical characteristics may be impaired.

  Therefore, in order not to generate a tensile stress between the inner conductor and the ceramic body, it is considered effective to reduce the contact rate between the inner conductor and the ceramic body.

  In view of this, a multilayer inductor has been proposed in which a conductor layer is opposed to a magnetic layer through a gap in a gap between adjacent magnetic layers (Patent Document 1).

  In Patent Document 1, by intentionally forming a gap between the magnetic layer and the conductor layer, the influence on the magnetic layer due to expansion and contraction of the conductor layer is reduced as much as possible, and the electrical characteristics are lowered. Is avoiding.

JP-A-4-65807

  However, in Patent Document 1, although a gap is formed between the magnetic layer and the conductor layer, the magnetic layer and the conductor layer are in partial pressure contact with each other. For this reason, in a small multilayer inductor (for example, vertical 0.1 mm, horizontal 0.5 mm, thickness 0.5 mm or less), electrical characteristics such as inductance and impedance are reduced, and reliability There was a problem that it was inferior.

  The present invention has been made in view of such problems, and further reduces stress, has good electrical characteristics even in a small product, and has a laminated structure such as a multilayer inductor having excellent reliability. It is an object of the present invention to provide a method for manufacturing a multilayer electronic component capable of manufacturing a mold electronic component.

As a result of intensive research conducted by the inventor in order to achieve the above object, the baking treatment is performed at a low temperature of 820 to 870 ° C. and the oxygen content is 0.1 to 10% by volume (hereinafter referred to as “vol%”). )) In a low-oxygen atmosphere, when voids are formed at the interface between the ceramic body and the internal conductor, even minute stresses can be removed, thereby providing good electrical characteristics and reliability. And obtained a knowledge that it is possible to manufacture a small-sized multilayer electronic component.

  In order to cause the conductive paste to thermally shrink more than the ceramic material, it is necessary to include resin particles having good thermal decomposability that do not inhibit sintering of the conductive particles in the conductive particles and the organic vehicle.

The present invention has been made on the basis of such knowledge, and the multilayer electronic component manufacturing method according to the present invention forms a laminate by alternately laminating conductive layers and ceramic layers to be internal conductors. Then, the multilayer body is subjected to a firing process to produce a ceramic body, and in the multilayer electronic component manufacturing method of manufacturing a multilayer electronic component having an internal conductor inside the ceramic body, after the firing process The conductive layer is formed using a conductive paste that shrinks more heat than the ceramic material constituting the ceramic layer, and the baking treatment is performed at a low temperature of 820 to 870 ° C. and the oxygen content is 0% by volume. performed in .1～10% low oxygen atmosphere, the formation of a space at the interface between the ceramic body and the inner conductor, the conductive paste includes at least conductive particles and an organic vehicle, 30 It contains the resin particle which has the thermal decomposition property which thermally decomposes at 0-500 degreeC .

Further, in order to lower the molding density without impairing the continuity of the inner conductor in the distribution on the sieve cumulative 50% diameter D ₅₀ of the resin particles with respect to the 50% size D ₅₀ of the conductive particles 0. The content of the resin particles is preferably 0.5 to 1.0 by volume ratio with respect to the content of the conductive particles.

  Furthermore, in order to obtain a desired conductive paste, the total content of the resin particles and the conductive particles is preferably 30 to 60 vol%.

  In addition, when the conductive particles and the resin particles are in the shape of a flake or a distorted shape, the molding density increases when crimped and high shrinkage cannot be obtained, and a desired void cannot be formed.

  That is, the particle shape of the conductive particles and the resin particles is preferably substantially spherical, and in this case, the ratio of the minor axis to the major axis is preferably 0.7 to 1.0.

  In addition, when the particle size of the conductive particles is excessively small, the conductive particles are aggregated and lack dispersibility, and the conductive particles easily diffuse during firing. On the other hand, when the particle size of the conductive particles is excessively large, the conductive particles are likely to be partially unevenly distributed, resulting in variation in distribution and a desired high shrinkage cannot be obtained, and the conductive particles are island-shaped. It becomes easy to sinter, and the continuity of the inner conductor is reduced. Furthermore, when the particle size distribution is even within a narrow range, the reduction of the molding density can be promoted and the shrinkage can be increased.

Therefore, the method of manufacturing multilayer electronic component of the present invention, the 50% size _{D 50} of the conductive particles is 1.0-4.0, 50% diameter _{D 50} of the resin particles is 0.25 to 6 The 10% diameter D _{10 of the} conductive particles and the resin particles is 0.5 μm or more with respect to the 50% diameter D _{50 in} a cumulative sieve distribution, and the conductive particles and the resin particles The 90% diameter D ₉₀ of the resin particles is characterized by being 2.0 or less with respect to the 50% diameter D ₅₀ .

According to the method for manufacturing a multilayer electronic component, since the firing process is performed in a low oxygen atmosphere having an oxygen content of 0.1 to 10% by volume, compared with the case where the firing process is performed in a conventional air atmosphere, 820. The baking treatment can be performed at a low temperature of ˜870 ° C. This is because firing in a low oxygen atmosphere causes oxygen defects in the ceramic, which promotes atomic diffusion. And by performing a baking process at such low temperature, the reactivity in the interface of a ceramic element | base_body and an internal conductor falls. Further, by performing the baking treatment in a low oxygen atmosphere, it is possible to shorten the time of exposure to high temperature for the same reason as described above, and therefore the expansion coefficient of the internal conductor is also reduced. And by such a fall of reactivity and a fall of the expansion coefficient of an internal conductor, the press-contact force (bonding force) to the ceramic element | base_body of an internal conductor becomes weak, and it can relieve a tensile stress. Also. By performing the firing treatment in a low oxygen atmosphere, the amount of oxygen involved in the bonding between the ceramic body and the internal conductor is reduced, and this can further reduce the tensile stress.

In addition, since the conductive paste contains at least conductive particles , an organic vehicle, and resin particles having thermal decomposability that are thermally decomposed at 300 to 500 ° C., the resin particles are formed before the conductive particles are sintered. Can be burned out or completely burned out. That is, the sintering of the conductive paste can be completed earlier than the sintering of the ceramic body, thereby forming a desired void at the interface.

Thus, in the present invention, the conductive paste containing the thermally decomposable resin particles that are thermally decomposed at 300 to 500 ° C. is used, and the baking treatment is performed at a low temperature of 820 to 870 ° C. in a low oxygen atmosphere. Do have, since thereby forming voids in the interface between the ceramic body and the inner conductor, can also be removed small stress at the interface, it has good electrical characteristics reliability superior compact laminate Type electronic parts can be manufactured.
Further, the 50% diameter _{D 50} of the resin particles is 0.25 to 1.50 to 50% diameter _{D 50} of the conductive particles, the content of the resin particles with respect to the content of the conductive particles Since the volume ratio is 0.5 to 1.0, the molding density at the time of pressure bonding can be lowered by mixing the thermally decomposable resin particles, the vaporization expansion is suppressed, and the tensile stress is relieved. It is possible to avoid the interface between the conductor and the ceramic body from being in a pressure contact state as much as possible, and it is possible to manufacture a highly reliable multilayer electronic component having good electrical characteristics.

In addition, since the total content of the resin particles and the conductive particles is 30 vol % to 60 vol %, the resin particles and the conductive particles are included in a desired amount in the conductive paste, and desired by firing. High shrinkage can be obtained, and an electrode pattern with a desired film thickness can be formed.

  In addition, since the particle shape of the conductive particles and the resin particles is substantially spherical and the ratio of the short axis to the long axis is 0.7 to 1.0, the distorted particles are conductive particles. In other words, high shrinkage can be ensured without entering between the resin particles and without increasing the molding density.

Further, the 50% size _{D 50} of the conductive particles is 1.0-4.0, the a 50% diameter _{D 50} of the resin particles 0.25～6.0Myuemu, and, in the distribution on the sieve integrated 10% diameter _{D 10} of the conductive particles and the resin particles, the is at both 0.5 or more to 50% diameter _{D 50,} 90% diameter _{D 90} of the conductive particles and the resin particles, the 50 since% diameter D are both 2.0 or less to _50, a better dispersibility of the particles, are aligned particle size distribution in a narrow range, it is possible to obtain the promotion to high shrinkage lowering of the molding density.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing an embodiment of a multilayer inductor as a multilayer electronic component according to the present invention, and FIG. 2 is a cross-sectional view of the multilayer inductor.

  1 and 2, the present multilayer inductor includes a ceramic body 1 made of a Ni—Zn—Cu ferrite-based material, external conductors 2a and 2b formed at both ends of the ceramic body 1, and ceramic bodies. It is comprised from the internal conductor 5 (5a-5g) formed in the inside of the body 1 at the coil shape.

  That is, in the multilayer inductor, gaps 3a to 3g are arranged inside the ceramic body 1, and the internal conductors 5a to 5g have gaps 4a to 4g and 4a 'to 4g' between the ceramic body 1. Thus, it is interposed in the gaps 3a to 3g.

  Specifically, as shown in FIG. 3, the inner conductor 5a is in partial contact with the ceramic body 1 so as not to be in a pressure contact state, and the surface of the inner conductor 5a has holes 6. Is formed. In the present embodiment, the internal conductor 5a is partially enlarged, but the same applies to the other internal conductors 5b to 5g.

  In this multilayer inductor, as shown in FIG. 2, the lead portion 7 of the inner conductor 5a is electrically connected to one outer conductor 2b, and the lead portion 8 of the inner conductor 5g is electrically connected to the other outer conductor 2a. Connected. Further, each of the inner conductors 5a to 5g is electrically connected in series via a via hole (not shown) formed in the vertical direction in the figure of the ceramic body 1, and is a coil wound in a counterclockwise direction. A pattern is formed.

  Next, a method for manufacturing the multilayer inductor will be described.

  First, using conductive particles and thermally decomposable resin particles, a conductive paste is produced that shrinks more thermally than the ceramic material that constitutes the ceramic body 1.

  Here, the conductive particles are not particularly limited as long as they have conductivity, and Ag, Pd, Pt, Au, Ni, Cu, or an alloy of two or more of these is used. can do.

  Next, the reason for using the thermally decomposable resin particles will be described in detail.

  The inner conductor 5 is shrunk due to the binder removal of the organic component contained in the conductive paste and the sintering of the conductive particles, but when the organic component remains as residual carbon in the binder removal process, In the firing process, residual carbon in the inner conductor 5 is vaporized and expanded to form holes 6, and the inner conductor 5 expands with a force to press the ceramic body 1 with the holes 6. As a result, the interface between the ceramic body 1 and the inner conductor 5 is in a pressure contact state, and oxygen diffusion is hindered, so that the oxygen remains at the interface. Are chemically bonded to each other, and tensile stress is generated.

  In other words, by preventing the interface from being in a pressure contact state, the oxygen diffuses outward without staying at the interface, the chemical bonding force is weakened, the tensile stress is relaxed, and a structure such as a crack or delamination is formed. The occurrence of defects can be avoided. In order to avoid the interface from being pressed as much as possible, the gaps 4 and 4 'are formed between the ceramic body 1 and the internal conductor 5 by using a conductive paste that shrinks more heat than the ceramic material. There is a need to.

In order to form such voids 4, 4 ′, the burning of the resin particles is started or completely burned out before the conductive particles are sintered, and the sintering of the conductive paste is performed in the ceramic body. It must be completed earlier than the sintering of 1. That is, for example, when Ag particles are used as the conductive particles, since the sintering temperature of Ag is 300 to 500 ° C., the resin particles are at least burned down at a low temperature of 300 to 500 ° C. which is the sintering temperature of Ag. Need to get started. Accordingly, it is necessary to use resin particles having good thermal decomposability that do not inhibit the sintering of such conductive particles.

  Therefore, in the present embodiment, resin particles having thermal decomposability are used.

  As such a thermally decomposable resin, for example, acrylic resin, methacrylic resin, polypropylene resin, polyethylene resin, polystyrene resin, polyester resin, polyolefin resin, polyisobutylene resin, polyethylene glycol resin, and the like can be used.

  When a resin having a compressive strength of 70 MPa or more is used, the resin particles can be prevented from being crushed in a step of pressure bonding a ceramic green sheet (hereinafter referred to as “ceramic sheet”), and higher electrical characteristics can be obtained. This is particularly preferable. As the resin having a compressive strength of 70 MPa or more, for example, polymethyl methacrylate (PMMA) resin, polystyrene resin, or the like can be used. The compressive strength of these resins according to ASTM test method D695 is, for example, 73 to 125 MPa for PMMA resin and 82 to 89 MPa for polystyrene resin.

  Further, the conductive particles and the resin particles satisfy the following (1) to (6).

(1) 50% diameter _{D 50} of the cumulative sieve on distribution of resin particles relative to the 50% size _{D 50} of the conductive particles 0.25 to 1.50
(2) The content of the resin particles is 0.5 to 1.0 by volume ratio with respect to the content of the conductive particles.
(3) The total content of resin particles and conductive particles is 30 to 60 vol% by volume.
(4) The particle shape of the conductive particles and the resin particles is substantially spherical, and the ratio of the short axis to the long axis is 0.7 to 1.0.
(5) 50% diameter _{D 50} of the conductive particles is 1.0-4.0, 50% diameter _{D 50} of the resin particles 0.25~6.0μm
(6) particle size distribution of the conductive particles and resin particles, both _{D 10 ≧ D 50/2,} D 90 ≦ 2D 50
Next, the above (1) to (6) will be described in detail.

(1) 50% diameter D _{50 of} resin particles
By mixing resin particles with low specific gravity with conductive particles, the molding density is lowered, so that the shrinkage of the inner conductor can be increased, thereby forming a gap between the inner conductor and the ceramic body. possible, the 50% diameter D ₅₀ of the resin particles is less than 0.25 to 50% diameter D ₅₀ of the conductive particles becomes relatively small particle size of the resin particles relative to the diameter of the conductive particles For this reason, the resin particles enter the gaps between the conductive particles and the molding density cannot be lowered, and the desired high shrinkage cannot be obtained.

On the other hand, when the 50% diameter D ₅₀ of the resin particles exceeds 1.50 to 50% diameter D ₅₀ of the conductive particles, too resin particles is relatively large, it can no longer be contacted Accordingly conductive particles to each other The conductive particles are sintered in an island shape, and the continuity of the internal conductor is lowered.

Therefore, in this embodiment, the 50% diameter _{D 50} of the resin particles with respect to the 50% size _{D 50} of conductive particles are made to be 0.25 to 1.50.

(2) Resin Particle Content When the resin particle content is less than 0.5 by volume with respect to the conductive particles, the resin particles contained in the conductive paste are excessively reduced, and the above (1) Similarly to the above, the molding density cannot be lowered and the desired high shrinkage cannot be obtained.

  On the other hand, if the content of the resin particles exceeds 1.0 in terms of volume ratio with respect to the conductive particles, the resin particles increase too much, and the conductive particles cannot be brought into contact with each other, and the conductive particles are sintered in an island shape. As a result, the continuity of the inner conductor is reduced.

  Therefore, in the present embodiment, the content of the resin particles is set to 0.5 to 1.0 by volume ratio with respect to the content of the conductive particles.

(3) Total content of resin particles and conductive particles The conductive paste is composed of conductive particles, resin particles, and an organic vehicle, but the total content of resin particles and conductive particles as solids is 60 vol. If it exceeds 50%, the content of the organic vehicle becomes too small to form a paste.

  On the other hand, when the total content of the resin particles and the conductive particles is less than 30 vol%, the organic vehicle content becomes too large, and even if a paste can be produced, the electrode pattern is set to a predetermined film thickness when applied. I can't.

  Therefore, in this embodiment, the total content of the resin particles and the conductive particles is set to 30 to 60 vol%.

(4) Particle shape of conductive particles and resin particles From the viewpoint of reducing the molding density and increasing the amount of shrinkage, the particle shape of the conductive particles and the resin particles are both spherical, and the ratio of the short axis to the long axis. (This ratio is hereinafter referred to as “sphericity”) is preferably 1.0, but it is difficult in terms of production technology to make all the sphericity of conductive particles and resin particles 1.0. It is.

  However, when the sphericity of the conductive particles and the resin particles becomes a distorted shape of less than 0.7, the conductive particles and the resin particles having a low sphericity enter in a form of filling the gaps between the substantially spherical particles, As a result, the molding density increases and the desired high shrinkage cannot be obtained. In addition, the internal conductor is usually formed by screen-printing a conductive paste, but conductive particles and resin particles having low sphericity are caught on the screen by such a printing process, resulting in a decrease in productivity.

  Therefore, in the present embodiment, the particle shape of the conductive particles and the resin particles is substantially spherical, and the sphericity is 0.7 to 1.0.

(5) Conductive Particle Size and Resin Particle Size Considering the continuity of the internal conductor 5, it is preferable that the conductive particles are uniformly dispersed in the internal conductor 5, but the 50% diameter D ₅₀ of the conductive particles is When the thickness is less than 1.0 μm, the conductive particles become too fine and agglomerate to make it difficult to uniformly disperse, and the conductive particles are easily diffused by the baking treatment. On the other hand, when the 50% diameter D ₅₀ of the conductive particles exceeds 4.0 μm, only the conductive particles or only the resin particles are arranged in the thickness direction of the internal conductor 5, or one of the conductive particles or the resin particles is extremely large. A small portion is generated, and uniform dispersion is impaired, so that a desired high shrinkage cannot be obtained or the continuity of the inner conductor 5 is lowered.

Therefore, the 50% diameter _{D 50} of the conductive particles and 1.0-4.0, and 50% diameter _{D 50} of the resin particles from the relation between the (1) and 0.25～6.0Myuemu.

(6) Particle Size Distribution of Conductive Particles and Resin Particles When the particle size distribution is wide, small particles easily enter between large particles, and the molding density increases and high shrinkage cannot be obtained. That is, it is preferable that uniform in particle size distribution narrow range of the conductive particles and the resin particles, in the present embodiment from such point of view, the particle size distribution of the conductive particles and resin particles, D ₁₀ ≧ D _50/2 , D ₉₀ ≦ 2D ₅₀ .

  And the resin particle and electroconductive particle which have the thermal decomposability which satisfy | fill said (1)-(6) are knead | mixed with an organic vehicle with a 3 roll mill, and an electroconductive paste is produced.

  The organic vehicle is composed of an organic binder and a solvent. As the organic binder, for example, ethyl cellulose resin, acrylic resin, butyral resin can be used, and as the solvent, for example, α-terpineol, tetralin, butyl carbitol is used. can do. Moreover, an organic binder and a solvent are prepared so that a compounding ratio may be set to 1: 9, for example.

Then, while making such conductive paste, _Fe 2 _{O 3} is (without 50mol) 45~50mol, NiO is 10～45Mol, CuO is 6～14Mol, so ZnO is 1~35mol These ferrite raw materials are weighed. In addition, it is also preferable to add oxides, such as Bi, Co, Sn, Zr, Mn, Nb, as an additive as needed.

  Subsequently, these weighed products are put into a ball mill, mixed and pulverized in a wet manner, and then dried and calcined to obtain a calcined product.

  Next, the calcined product is sufficiently wet pulverized again with a ball mill and dried to prepare a calcined powder. After that, the calcined powder is mixed with a binder, a plasticizer, and a dispersant, and dispersed in a solvent. A ceramic slurry is prepared, and the ceramic slurry is formed into a sheet shape by a doctor blade method or the like to produce a ceramic sheet.

  Next, a via hole is formed at a predetermined position on the ceramic sheet, and the conductive paste is screen-printed on the surface of the ceramic sheet to form a predetermined electrode pattern.

  After this, a plurality of ceramic sheets with electrode patterns formed thereon are stacked so that they can be electrically connected in series through via holes to form a laminate, and the ceramic sheets with no electrode patterns formed thereon The laminate is sandwiched and crimped to produce a crimping block.

  Next, after cutting the pressure-bonding block into a predetermined size, a binder removal process is performed at a predetermined temperature (for example, 500 ° C. or less), and then a baking process is performed in a low oxygen atmosphere with an oxygen content of 0.1 to 10 vol%. A ceramic sintered body is produced.

By performing the firing process in a low oxygen atmosphere in this manner, the firing process can be performed at a low temperature of 820 to 870 ° C. compared to the case of performing the firing process in a conventional air atmosphere. Stress can be relaxed.

  That is, by performing low-temperature firing, the reactivity at the interface between the ceramic body 1 and the inner conductor 5 is reduced, and it is possible to avoid the object to be fired from being exposed to a high temperature for a long time. The expansion coefficient of the conductor 5 is reduced. As a result, the pressure contact force (bonding force) of the inner conductor 5 to the ceramic body 1 is weakened, and the tensile stress can be relaxed.

  In addition, by performing the firing process in a low oxygen atmosphere, the amount of oxygen involved in the bonding between the ceramic body 1 and the inner conductor 5 is reduced, and this can further reduce the tensile stress. In addition, by performing the firing process in a low oxygen atmosphere, it is possible to avoid as much as possible the Cu component contained in the ceramic body 1 from dissociating and precipitating at the interface, thereby reducing the reactivity at the interface. Thus, further stress relaxation can be achieved.

  By performing firing in a low-oxygen atmosphere in this way, the tensile stress can be further reduced, and even with a small multilayer inductor, electrical characteristics such as impedance and inductance can be achieved without causing a decrease in permeability. Can be made good.

  However, the oxygen content needs to be 0.1 to 10 vol% as described above.

  That is, when the oxygen content is less than 0.1 vol%, the oxygen content becomes too low and the reduction action is strengthened. For this reason, firing is not promoted even if the crimping block is subjected to firing treatment because oxygen is released from the ferrite too much. Therefore, it is difficult to obtain a multilayer inductor having a desired magnetic permeability.

  On the other hand, if the oxygen content exceeds 10 vol%, the firing atmosphere approaches the air atmosphere, so that sufficient relaxation of the tensile stress cannot be performed, leading to a decrease in electrical characteristics such as inductance and impedance.

  Therefore, in the present embodiment, the oxygen content is set to 0.1 to 10 vol%.

  In the binder removal treatment, the resin particles start to be burned out at a lower temperature (for example, 150 ° C.) than the sintering temperature of the conductive particles (for example, 300 ° C.). The binder removal treatment is promoted, and the carbon component is evaporated without remaining at a firing temperature of 500 ° C. or higher.

  Next, the ceramic sintered body is barrel-polished to form the ceramic body 1, and then a conductive paste is applied to both ends of the ceramic body 1 and baked to form external conductive portions.

  Thereafter, electrolytic plating is performed, and a nickel film and a tin film are sequentially formed on the surface of the external conductive portion to form the external conductors 2a and 2b, whereby a multilayer inductor is manufactured.

  Thus, according to the said manufacturing method, since the baking process is performed in the low oxygen atmosphere whose oxygen content is 0.1-10 vol%, the reactivity in the interface of the ceramic element | base_body 1 and the internal conductor 5 is reduced. In addition, the amount of oxygen involved in the bonding between the ceramic body 1 and the inner conductor 5 can be reduced, thereby reducing the pressure contact force (bonding force) and further reducing the tensile stress. Therefore, a small-sized multilayer inductor having good electrical characteristics such as impedance and inductance can be easily manufactured with high efficiency without impairing the magnetic permeability.

  The present invention is not limited to the above embodiment. In the above embodiment, a ferrite-based material is used as the ceramic material, but it goes without saying that it can be applied to glass powder materials and other ceramic materials, and therefore, it is applicable to electronic components other than multilayer inductors, such as multilayer ceramic capacitors. It goes without saying that can also be applied.

  Moreover, in the said embodiment, although the sheet | seat construction method which laminates | stacks several ceramic sheets was used, it cannot be overemphasized that other construction methods, such as a printing construction method, can be used, for example.

  Next, examples of the present invention will be specifically described.

Example 1
The present inventors have, _Fe 2 _{O 3} is 49.0Mol, is ZnO 29.0mol, NiO were weighed 14.0mol, _Fe 2 _O 3, ZnO as CuO is 8.0 mol, NiO, and CuO Further, Bi ₂ O ₃ and Mn ₃ O ₄ were weighed so that Bi ₂ O ₃ was 0.25 wt% and Mn ₃ O ₄ was 0.15 wt%.

  Next, the above-mentioned weighed material, which is a raw material for ferrite, is put into a ball mill having PSZ (partially stabilized zirconia) having a diameter of 1 mm as a grinding medium, and is mixed and pulverized in a wet manner to form a slurry powder. And separated by a spray dryer and calcined at a temperature of 650 ° C. for 2 hours to prepare a calcined product.

  Next, the calcined product was re-introduced into the ball mill, sufficiently pulverized by a wet process, and dried by a spray dryer to prepare a ferrite raw material (calcined powder).

  Next, to this calcined powder, polyvinyl butyral as a binder, dibutyl phthalate as a plasticizer, polycarboxylic acid ammonium salt as a dispersant, toluene and ethyl alcohol as solvents are added and mixed to prepare a ceramic slurry, and then the ceramic The rally was formed into a sheet shape by the doctor blade method to produce a magnetic sheet (ceramic sheet) having a thickness of 50 μm. And the via hole was penetrated in the predetermined location of the magnetic material sheet using the laser processing machine.

  On the other hand, a conductive paste was produced as follows.

  That is, first, α-terpineol is used as a solvent, ethyl cellulose resin is used as an organic binder, and ethyl cellulose resin is dissolved in α-terpineol so that the ratio of ethyl cellulose resin to α-terpineol is 10 vol%: 90 vol%. An organic vehicle was prepared.

Then, 10% diameter _{D 10} of 1.03 .mu.m, 1.52 .mu.m 50% diameter _{D 50,} 90% diameter _{D 90} of _{2.30μm (D 10 = 1.03 ≧ 0.76} = D 50/2, D 90 = 2.30 ≦ 3.04 = 2D ₅₀ ), Ag particles with a sphericity of 0.9, D ₁₀ diameter of 0.73 μm, D ₅₀ diameter of 1.04 μm, D ₉₀ diameter of 1.55 μm (D _{10 = 0.73 ≧ 0.52 = D 50} /2, D 90 = 1.55 ≦ 2.08 = 2D 50), 50% diameter of the sphericity was prepared 0.9 PMMA resin (Ag particles PMMA resin 50% diameter D _{50 with} respect to D ₅₀ : 0.68).

  The particle size of Ag particles and PMMA resin was measured with a Microtrac HRA particle size distribution analyzer (9320-X100 manufactured by Leeds & No Step), which is a laser diffraction / scattering particle size distribution measuring device. Secondary Electron Microscope, JEOL JSM-5310) was used for the measurement.

  Next, Ag particles and PMMA resin are sufficiently kneaded with an organic vehicle (ethyl cellulose resin: α-terpineol = 6 vol%: 54 vol%) by a three roll mill, and the mixing ratio is Ag particles: 27.4 vol%, PMMA resin: A conductive paste was prepared so as to be 22.7 vol% and organic vehicle: 49.9 vol% (the volume ratio of Ag particles and PMMA resin was 0.828, and the total content was 50.1 vol%).

  Next, screen printing was performed on the ceramic sheet using the conductive paste to form an electrode pattern having a film thickness of 40 μm and a line width of 120 μm. The film thickness was measured with a laser displacement meter.

After that, a plurality of magnetic sheets on which electrode patterns are formed are stacked so that the electrode patterns can be connected in series in a coil shape to form a laminate, and a magnetic sheet on which no electrode patterns are formed. The laminate was sandwiched and pressure-bonded at 9.8 × 10 ⁷ Pa (1,000 kgf / cm ² ) to prepare a pressure-bonding block.

  Next, after cutting the pressure-bonded block into a predetermined size, a binder removal process is performed at a temperature of 500 ° C. or less, and a firing process is performed by holding at a temperature of 840 ° C. for 90 minutes in a low oxygen atmosphere with an oxygen content of 1.3 vol%. Then, a ceramic sintered body having an internal conductor interposed therein was produced.

  Next, after separately preparing an Ag paste for outer conductor in which glass frit and an organic vehicle are added and dispersed in Ag powder, the ceramic sintered body is deburred by barrel polishing to obtain a ceramic body. The external conductor Ag paste was applied to both ends of the ceramic body and baked at 700 ° C. to obtain external conductive portions.

  Thereafter, a known electrolytic plating is performed to sequentially produce a nickel film and a tin film on the surface of the conductive portion to form an outer conductor, whereby the size is 0.6 mm in length, 0.3 mm in width, 0.3 mm in thickness. A 3 mm multilayer inductor was manufactured.

(Example 2)
A multilayer inductor of Example 2 was produced by the same method and procedure as in Example 1 except that the oxygen content was 5 vol% and the firing temperature was 850 ° C.

(Example 3)
A multilayer inductor of Example 3 was produced by the same method and procedure as Example 1 except that the oxygen content was 10.0 vol% and the firing temperature was 860 ° C.

Example 4
A multilayer inductor of Example 4 was produced by the same method and procedure as in Example 1 except that the oxygen content was 0.1 vol% and the firing temperature was 830 ° C.

(Example 5)
A multilayer inductor of Example 5 was produced by the same method and procedure as in Example 1 except that the oxygen content was 0.01 vol% and the firing temperature was 820 ° C.

(Example 6)
A multilayer inductor of Example 6 was produced by the same method and procedure as in Example 1 except that the firing temperature was 870 ° C. and the holding time was 30 minutes.

(Example 7)
A multilayer inductor of Example 7 was produced by the same method and procedure as in Example 1 except that the firing temperature was 870 ° C.

(Comparative Example 1)
A multilayer inductor of Comparative Example 1 was produced by the same method and procedure as in Example 1 except that the oxygen content was 20.7 vol% (atmosphere) and the firing temperature was 870 ° C.

(Comparative Example 2)
A multilayer inductor of Comparative Example 2 was produced by the same method and procedure as in Example 1 except that the oxygen content was 20.7 vol% (atmospheric atmosphere).

(Comparative Example 3)
A multilayer inductor of Comparative Example 3 was produced by the same method and procedure as in Example 1 except that the oxygen content was 0.001 vol% and the firing temperature was 820 ° C.

(Comparative Example 4)
A multilayer inductor of Comparative Example 4 was produced by the same method and procedure as in Example 1 except that the oxygen content was 15.0 vol% and the firing temperature was 870 ° C.

(Comparative Example 5)
After the Ag particles and the organic vehicle are weighed so that the Ag particle content is 33.7 vol% and the organic vehicle content is 66.3 vol%, the Ag particles are mixed with the organic vehicle. A conductive paste containing no PMMA resin (resin particles) was prepared by kneading.

  Next, a magnetic material sheet was produced by the same method and procedure as in Example 1 using the conductive paste.

  Thereafter, firing was carried out while maintaining the oxygen content at 20.7 vol% (atmosphere) and at a temperature of 870 ° C. for 90 minutes, to produce a multilayer inductor of Comparative Example 5.

(Comparative Example 6)
Using the conductive paste of Comparative Example 5, a magnetic sheet was prepared by the same method and procedure as in Example 1, and the oxygen content was 20.7 vol% (atmosphere) and held at a temperature of 840 ° C. for 90 minutes. A firing process was performed to produce a multilayer inductor of Comparative Example 6.

(Comparative Example 7)
A multilayer inductor of Comparative Example 7 was produced by the same method and procedure as in Example 1 except that the magnetic material sheet was produced by the same method and procedure as in Example 1 using the conductive paste of Comparative Example 5. .

(Comparative Example 8)
A magnetic sheet was produced by the same method and procedure as in Example 1 using the conductive paste of Comparative Example 5, and the comparative example was the same as in Example 1 except that the firing temperature was 870 ° C. 8 multilayer inductors were produced.

  Next, an inductance of 1 MHz and an impedance of 100 MHz were measured with an RF impedance analyzer (HP4291A manufactured by Hewlett-Packard Company).

  In addition, using the above ferrite raw materials, toroidal cores having an outer diameter of 15.5 mm, an inner diameter of 7.5 mm, and a thickness of 1 mm were separately prepared under the firing conditions of each of the examples and comparative examples, and corresponded to these examples and comparative examples. The permeability at 1 MHz was measured with the RF impedance analyzer. Incidentally, the magnetic permeability was measured by separately manufacturing the toroidal core as described above, and when the magnetic permeability of the multilayer inductor was directly measured, there was a risk of leakage in the magnetic flux, so that accurate magnetic permeability could be measured. It will be difficult.

  Furthermore, using this toroidal core, the sintered density corresponding to each Example and Comparative Example was measured by Archimedes method.

この表１から明らかなように比較例１は、大気雰囲気で焼成処理を行なっているため、セラミック素体と内部導体との界面で生じる微小な応力の影響を受け、インピーダンスが３．０μＨ、インダクタンスが４８０Ωと低く、電気特性が悪化している。 Table 2 shows firing conditions (oxygen content, firing temperature, holding time), inductance, impedance, magnetic permeability, and sintered density in each example and comparative example.

As can be seen from Table 1, since Comparative Example 1 is fired in an air atmosphere, it is affected by a minute stress generated at the interface between the ceramic body and the internal conductor, and has an impedance of 3.0 μH, inductance Is as low as 480Ω, and the electrical characteristics are deteriorated.

Also in Comparative Example 2, the firing process was performed in an air atmosphere, and the firing temperature was as low as 840 ° C., so the sintered density was as low as 4.89 × 10 ³ kg / m ^3, and it was not sufficiently sintered. The characteristics and permeability are also extremely deteriorated.

  In Comparative Example 3, since the oxygen content is excessively low at 0.001 vol%, a desired magnetic material cannot be obtained even when sintered, and thus the electrical characteristics and magnetic permeability are deteriorated.

  Since Comparative Example 4 has a high oxygen content of 15.0 vol%, the characteristics are hardly different from those in the case of firing in an air atmosphere (Comparative Example 2), and electrical characteristics and magnetic permeability are deteriorated.

  In Comparative Examples 5 to 8, since the internal conductor is formed using the conductive paste containing no resin particles, no gap is formed between the ceramic body and the internal conductor. Since the interface is pressed, the tensile stress is large, which leads to a decrease in inductance and impedance.

  On the other hand, Examples 1 to 7 are fired in a low oxygen atmosphere having an oxygen content of 0.1 to 10.0 vol%, and thus can be fired at a low temperature and have electrical characteristics such as inductance and impedance. It was found that a good multilayer inductor could be manufactured.

  Further, as is clear from Example 6, even when the firing process was performed in a low oxygen atmosphere with a holding time of 30 minutes, the same permeability as that obtained when fired in an air atmosphere (Comparative Example 1) can be obtained, Therefore, it is possible to manufacture a small-sized multilayer inductor having good electrical characteristics such as impedance and inductance without losing the permeability by firing for a short period of time as compared with the case of firing in an air atmosphere.

  In addition, although the magnetic permeability of Example 1 and Comparative Examples 1, 5, and 7 is equivalent (319 to 320), the impedance of Comparative Examples 1, 5, and 7 is smaller than the impedance of Example 1. The reason is that the properties of the ferrite itself are substantially the same, but when a multilayer inductor is actually manufactured, the impedance is reduced by the stress of the internal conductor.

1 is a perspective view showing an embodiment of a multilayer inductor as a multilayer electronic component according to the present invention. It is a longitudinal cross-sectional view of the said multilayer inductor. It is the A section expanded sectional view of FIG.

Explanation of symbols

1 Ceramic element body 4 Air gap 4 'Air gap 5 Inner conductor (inner conductor)

Claims (5)

After forming a laminated body by alternately laminating a conductive layer and a ceramic layer to be an internal conductor, the laminated body is fired to produce a ceramic body, and the internal conductor is provided inside the ceramic body. In the manufacturing method of the multilayer electronic component for manufacturing the multilayer electronic component,
After forming the conductive layer using a conductive paste that shrinks more heat than the ceramic material constituting the ceramic layer after the firing treatment ,
A low temperature pre-Symbol baked eight hundred twenty to eight hundred seventy ° C. performed oxygen content in a low oxygen atmosphere from 0.1 to 10% by volume% to form a void at the interface between the ceramic body and the inner conductor ,
The method for producing a multilayer electronic component, wherein the conductive paste contains at least conductive particles , an organic vehicle, and resin particles having thermal decomposability that are thermally decomposed at 300 to 500 ° C. The 50% diameter D ₅₀ of the resin particles is 0.25 to 1.50 with respect to the 50% diameter D ₅₀ of the conductive particles in the cumulative sieve distribution, and the content of the resin particles is that of the conductive particles. 2. The method for manufacturing a multilayer electronic component according to claim 1, wherein the volume ratio is 0.5 to 1.0 with respect to the content . 3. The method of manufacturing a multilayer electronic component according to claim 1, wherein the total content of the resin particles and the conductive particles is 30 to 60% by volume . The particle shape of the said electroconductive particle and the said resin particle is substantially spherical shape, and the ratios of the short axis with respect to a major axis are both 0.7-1.0, The Claim 1 thru | or 3 characterized by the above-mentioned. The manufacturing method of the multilayer electronic component in any one. The conductive particles have a 50% diameter D ₅₀ of 1.0 to 4.0 μm, and the resin particles have a 50% diameter D ₅₀ of 0.25 to 6.0 μm ,
And 10% diameter D ₁₀ of the conductive particles in the distribution on the sieve integrated and the resin particles are in both the 50% diameter D ₅₀ to 0.5 or more, 90% of the conductive particles and the resin particles 5. The method for manufacturing a multilayer electronic component according to claim 1 , wherein both the diameters D ₉₀ are 2.0 or less with respect to the 50% diameter D ₅₀ .

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