JP2014146654A - Laminated electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated electronic component capable of suppressing the occurrence of delamination even when an inner conductor layer is multilayered.SOLUTION: A laminated electronic component includes: a laminated part 9 where a ceramic insulator layer 5 and an inner conductor layer 7 are alternately laminated to form a multilayer; and ceramic cover layers 11 provided on both end faces in the lamination direction of the laminated part 9, respectively. In the inner conductor layer 7 in contact with the cover layer 11 among the inner conductor layers 7, a metal oxide phase 13 constituting the inner conductor layer 7 is formed so as to penetrate through the inner conductor layer 7 in the thickness direction.

Description

  The present invention relates to a multilayer electronic component used when configuring various electronic circuits.

  2. Description of the Related Art Conventionally, there has been known a multilayer electronic component manufactured by stacking a plurality of insulator layers and a plurality of internal conductor layers and then firing them integrally (for example, see Patent Document 1). In such a multilayer electronic component, when several internal conductor layers having substantially the same shape and overlapping are laminated, in particular, the inner conductor layers located at the uppermost layer and the lowermost layer in the lamination direction and the cover laminated on the main surface thereof There is a problem that delamination is likely to occur between the layers. The reason is that the inner conductor layer and the cover layer are difficult to adhere because the materials are completely different, for example, metal and ceramics, and the thermal expansion coefficients of the inner conductor layer and the ceramic insulator layer are greatly different. This is because distortion due to the difference in shrinkage between the inner conductor layer and the insulator layer increases.

JP 2011-129841 A

  Accordingly, an object of the present invention is to provide a multilayer electronic component that can suppress the occurrence of delamination even if the inner conductor layer is made multilayer.

  The multilayer electronic component of the present invention includes a laminated portion in which ceramic insulator layers and internal conductor layers are alternately laminated, and a ceramic cover layer provided on each end surface of the laminated portion in the lamination direction. In the multilayer electronic component having the inner conductive layer, the inner conductor layer in contact with the cover layer among the inner conductor layers has a metal oxide phase constituting the inner conductor layer penetrating the inner conductor layer in the thickness direction. It is formed as follows.

  According to the present invention, it is possible to obtain a multilayer electronic component in which delamination does not occur even when a large number of internal conductor layers are stacked.

FIG. 1 is a schematic cross-sectional view showing an embodiment of a multilayer electronic component of the present invention. It is the schematic sectional drawing which expanded the cover layer vicinity (A part) in FIG.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of a multilayer electronic component of the present invention. 2 is an enlarged schematic cross-sectional view of the vicinity of the cover layer (part A) in FIG.

  As an example of the multilayer electronic component of the present invention, a multilayer capacitor will be described below as an example. Needless to say, the present invention is not limited to capacitors and can be widely applied to electronic parts in which ceramic insulator layers and internal conductor layers are laminated in multiple layers, such as actuators, filters, and inductors.

The multilayer electronic component of the present embodiment has external electrodes 3 at opposite ends of the electronic component body 1. The electronic component body 1 includes a laminated portion 9 in which ceramic insulator layers 5 and internal conductor layers 7 are alternately laminated, and a ceramic cover provided on both end faces 9a of the laminated portion 9 in the laminating direction. Layer 11.

  Here, in the inner conductor layer 7 in contact with the cover layer 11 among the inner conductor layers 7, the metal oxide phase 13 constituting the inner conductor layer 7 penetrates the inner conductor layer 7 in the thickness direction. It is formed as follows.

  Usually, in a multilayer electronic component having a ceramic cover layer 11 on an end surface 9a of a laminated portion 9 in which ceramic insulator layers 5 and internal conductor layers 7 are laminated in multiple layers, the internal conductor layers 7 and the cover layers Since the material is significantly different from 11, it is difficult to bond. Further, since the inner conductor layer 7 and the ceramic insulator layer 5 are made of different materials as described above, their thermal expansion coefficients are also greatly different.

  When the multilayer electronic component having such a configuration is placed in an environment with a large temperature change such as a solder reflow process, delamination occurs at the interface between the ceramic insulator layer 5 and the internal conductor layer 7. is there. This delamination is particularly likely to occur at the interface between the end surface 9a of the laminated portion 9 and the cover layer 11 for the reasons described above.

  In the multilayer electronic component of the present embodiment, among the internal conductor layers 7 constituting the multilayer portion 9, the metal oxide phase 13 is present in the internal conductor layer 7 in contact with the cover layer 11. 7, the inner conductor layer 7 and the cover layer 11 are partially but firmly bonded with the same oxide. Thereby, delamination between the inner conductor layer 7 and the cover layer 11 can be suppressed.

  In this case, since the metal oxide phase 13 penetrates the inner conductor layer 7 in the thickness direction, the cover layer 11 and the ceramic insulating layer 5 of the laminated portion 9 are connected via the metal oxide phase 13. Therefore, the adhesiveness between the inner conductor layer 7 and the cover layer 11 can be further strengthened, contributing to prevention of delamination.

  In the multilayer electronic component of this embodiment, when the inner conductor layer 7 having the metal oxide phase 13 is provided over a plurality of layers from the cover layer 11 side, the one closer to the cover layer 11 Since the thermal expansion coefficient of the inner conductor layer 7 is closer to the thermal expansion coefficient of the ceramic cover layer 11, the stress at the interface between the laminated portion 9 and the cover layer 11 can be further reduced, and the amount of strain can be reduced. Thereby, generation | occurrence | production of the delamination in the interface of the laminated part 9 and the cover layer 11 can further be suppressed.

  The number of layers of the inner conductor layer 7 having the metal oxide phase 13 is effective if one layer is provided on the end face 9a side of the laminated portion 9, but the inner conductor layer 7 having the metal oxide phase 13 is effective. Although the occurrence of delamination can be suppressed when the number of layers increases, for example, in the case of a capacitor or the like, the capacitance decreases greatly. For this reason, the number of layers of the inner conductor layer 7 having the metal oxide phase 13 is desirably 10 layers or less from the end face 9 a side in the laminated portion 9.

The thermal expansion coefficient of the main component metal of the inner conductor layer 7 constituting the multilayer electronic component of the present embodiment is desirably 12 × 10 ^{−6 to} 20 × 10 ⁻⁶ / ° C., and such a thermal expansion coefficient is As a metal material to have, nickel (12.8 × 10 ⁻⁶ / ° C.), copper (16.8 × 10 ⁻⁶ / ° C.), palladium (11.8 × 10 ⁻⁶ / ° C.) and silver (18.9) It is preferable to apply one kind selected from × 10 ⁻⁶ / ° C. or an alloy thereof.

As a material of the ceramic insulator layer 5 and the cover layer 11, ceramic materials applied to capacitors, actuators, inductors, filters, etc. are preferable. For example, barium titanate, lead zirconate titanate, ferrite, magnesia, calcia, pentoxide A composite oxide composed of at least two metal oxides selected from niobium and titanium dioxide is preferred. The thermal expansion coefficient of these materials is preferably 9 × 10 ^{−6 to} 11 × 10 ⁻⁶ / ° C.

  In the multilayer electronic component of the present embodiment, it is desirable that the average thickness of the internal conductor layer 7 is thinner as it is closer to the cover layer 11 side than the central portion in the stacking direction. That is, it is desirable that the average thickness of the inner conductor layer 7 having the metal oxide phase 13 is thinner than the average thickness of the inner conductor layer 7 located at the center in the stacking direction. If the average thickness of the inner conductor layer 7 on the cover layer 11 side is thin, the rigidity per layer of the inner conductor layer 7 can be reduced, so that the interface 9a between the inner conductor layer 7 and the cover layer 11 can be reduced. Even when distortion occurs, the internal conductor layer 7 can easily follow the deformation of the cover layer 11 and the ceramic insulating layer 5, thereby further suppressing the occurrence of delamination.

  As the above-described multilayer electronic component, the average thickness of the ceramic insulator layer 5 is 1 to 30 μm, the average thickness of the internal conductor layer 7 is 0.5 to 20 μm, and the number of the internal conductor layers 7 in the multilayer portion 9 is 100 layers. As described above, the thickness of the cover layer is preferably 0.02 or more when the thickness in the stacking direction of the stacked portion 9 is 1, which is suitable for a multilayer electronic component having a high layer and a thin layer.

  Next, a method for manufacturing the multilayer electronic component of the present embodiment will be described using a capacitor as an example. First, a dielectric powder is prepared as a material for the ceramic insulator layer 5, an organic vehicle is added thereto to prepare a ceramic slurry, and then a ceramic green sheet using a sheet forming method such as a doctor blade method or a die coater method. Is made.

  Next, a conductor paste mainly composed of nickel powder is prepared. In this case, as the nickel powder, it is desirable to use nickel powder containing fine nickel powder having an average particle diameter of 0.1 μm or less.

  Next, a pattern sheet on which a rectangular internal conductor pattern is formed is formed on the main surface of the ceramic green sheet using a conductor paste. At this time, the conductive pattern of the pattern sheet that is stacked on the end face side of the laminate that becomes the laminate portion 9 after firing has a plate making line width (the thickness of the mesh material) of the printing screen rather than the pattern sheet that is arranged in the center portion of the laminate. Use a thicker one. The plate-making line width for forming the conductor pattern of the pattern sheet to be superimposed on the end face side is desirably 1.2 times or more the plate-making line width for forming the conductor pattern of the pattern sheet located at the center. In this case, both the thicknesses of the plate making lines should be the same. That is, it is preferable to use a plate for printing the conductive pattern of the pattern sheet to be overlapped on the end face side with an aperture ratio lower than that of the screen for printing the conductive pattern of the pattern sheet located at the center.

  In this way, the conductor pattern of the pattern sheet stacked on the end face side is uneven and has a partly thinner area than the conductor pattern of the pattern sheet located at the center of the laminate, and this thin conductor pattern portion is The ratio of the oxidized region is larger than that of the thicker portion, and the metal oxide phase 13 that partially constitutes the inner conductor layer 7 can be formed in the plane of the inner conductor layer 7.

  In the conventional capacitor, the same screen has been used as a printing screen, but in this case, an extremely thin metal oxide film is formed on the surface of the internal conductor layer 7 in the manufacturing process. The metal oxide phase 13 that penetrates the inner conductor layer 7 is not formed.

  Next, a core laminated body is formed by stacking a plurality of pattern sheets. In this case, the core laminate is provided with a pattern sheet in which a conductor pattern is formed using a screen with a narrow plate making line width (high aperture ratio) at the center in the laminating direction, and the plate making wire is placed on the upper and lower end faces of the core laminate. A pattern sheet on which a conductor pattern is formed is placed using a wide screen (low aperture ratio).

  Next, a mother laminate having a plurality of laminates to be the electronic component main body 1 by stacking a predetermined number of ceramic green sheets on which the conductor pattern is not formed on the upper and lower surfaces of the core laminate, and performing pressure heating treatment. Form. Next, the base laminate is cut to obtain a laminate. Next, the electronic component main body 1 is manufactured by baking the manufactured laminated body on predetermined conditions.

  Next, the external electrode 3 is formed on the end portion including the end face where the internal conductor layer 7 of the electronic component main body 1 obtained by firing is exposed, thereby completing the multilayer electronic component.

  In the multilayer electronic component thus obtained, of the internal conductor layers 7, at least the internal conductor layer 7 in contact with the cover layer 11 has a metal oxide phase 13 that constitutes the internal conductor layer 7. Is formed so as to penetrate through in the thickness direction.

  Although the capacitor has been described above as an example, the multilayer electronic component of the present invention can be used according to the material for the ceramic insulator layer 5 and the material for the internal conductor layer 7 applied to the actuator, the inductor, and the filter, respectively. Can be produced.

Hereinafter, a multilayer capacitor was specifically manufactured to confirm the effect of the present invention. First, the following dielectric powder was prepared as a material for the ceramic insulator layer. Barium titanate powder, MgO powder, Y ₂ O ₃ powder and MnCO ₃ powder were prepared as raw material powders for the dielectric powder. These various powders, when the barium titanate powder amount is 100 mol, 0.5 mol of MgO _powder, Y 2 _{O 3} powder 1 mol, and 0.5 mol addition of MnCO ₃ powder, further, titanium A dielectric powder was prepared by adding 1 part by mass of glass powder (SiO ₂ = 55, BaO = 20, CaO = 15, Li ₂ O = 10 (mol%)) to 100 parts by mass of barium acid powder. Next, this dielectric powder was wet mixed using a zirconia ball having a diameter of 5 mm and a mixed solvent composed of toluene and alcohol as a solvent.

  Next, the wet-mixed powder is put into a mixed solvent of toluene and alcohol in which polyvinyl butyral resin is dissolved, wet-mixed using a zirconia ball having a diameter of 5 mm, and a ceramic slurry is prepared. Produced a ceramic green sheet having a thickness of 2.5 μm.

  Next, a rectangular conductor pattern was formed on the upper surface of the ceramic green sheet to form a pattern sheet. The conductor paste for forming the conductor pattern is 20% by weight of barium titanate powder as a co-material with respect to 45% by weight of Ni powder, 30% by weight of an organic vehicle consisting of 5% by weight of ethyl cellulose and 95% by weight of octyl alcohol. Was kneaded with three rolls. Ni powder having a particle size in the range of 10 to 90% in the range of 10 to 90% in terms of cumulative percentage in the particle size distribution was used.

At this time, the conductor pattern of the pattern sheet to be overlapped on the end face side of the laminate uses a screen having a plate making line width of about 30 μm, while the conductor pattern of the pattern sheet disposed at the center of the laminate has a screen having a plate making line width of about 20 μm. Was used. The aperture ratio of a screen having a plate-making line width of about 30 μm was about 40%, and that of a screen having a plate-making line width of about 20 μm was about 60%.

  Next, a plurality of pattern sheets having a conductor pattern formed using a screen having a plate making line width of about 20 μm among the prepared pattern sheets are stacked, and then a screen having a plate making line width of about 30 μm is formed on the upper and lower surfaces of this laminate. A core laminated body is formed by laminating pattern sheets formed with conductor patterns using a ceramic, and further, ceramic green sheets not formed with conductor patterns are stacked on the upper and lower surfaces, respectively, and subjected to pressure heating treatment to form an electronic component body. A base laminate having a plurality of laminates was formed. Then, this base material laminated body was cut | disconnected to the predetermined dimension, and the laminated body was formed. The number of laminated inner conductor layers in the laminate was 147.

Next, the prepared laminate is degreased in the air, and then fired at 1140 ° C. for 2 hours in a hydrogen-nitrogen mixed gas atmosphere at an oxygen partial pressure of 10 ⁻⁸ Pa. Was made. The size of the manufactured electronic component main body corresponds to 1005 type, and the size was approximately 0.95 mm × 0.48 mm × 0.48 mm. The average thickness of the ceramic insulator layer was 2 μm, and the average thickness of one layer of the inner conductor layer located at the center of the laminated portion was 1 μm. The average thickness of the inner conductor layer on the cover layer side was 0.9 μm. The average thickness of the cover layer was 20 μm. In addition, the design value of the capacitance obtained from the manufactured electronic component body (capacitance expressed in a state where there is no void in the area of the effective area where the internal conductor layers overlap each other with the ceramic insulator layer sandwiched therebetween) is Estimated to be 1.15 μF.

Next, the produced electronic component main body was heat-treated at 900 to 1000 ° C. for 5 hours in a nitrogen atmosphere (oxygen partial pressure: 10 ⁻⁶ Pa).

  Next, barrel polishing treatment was performed on the manufactured electronic component main body to sufficiently expose the inner conductor layer on the end surface of the electronic component main body.

  Next, a copper paste is applied to the end of the barrel-polished electronic component body and heated under conditions of about 800 ° C., oxygen partial pressure of 1 Pa, and maximum temperature holding time of 0.2 hours to form external electrodes. did.

  Next, an Ni plating film and an Sn plating film were sequentially formed on the surface of the external electrode by electrolytic plating to produce a multilayer capacitor.

  Next, the following evaluation was performed on the manufactured multilayer capacitor.

  The oxide phase of the metal composing the inner conductor layer formed on the inner conductor layer of the laminated portion of the capacitor was confirmed by observing with a metal microscope and a scanning electron microscope after the capacitor was polished in cross section. At this time, the presence or absence of oxygen in the metal oxide phase was identified using a wavelength dispersion analyzer attached to a scanning electron microscope. The metal oxide phase was a blackened portion in a photograph taken with a scanning electron microscope.

  The ratio of the metal oxide phase is determined by taking a photograph of a cross-polished capacitor with a scanning electron microscope, drawing a straight line parallel to the internal conductor layer on the photo, and measuring the length of the portion where the metal oxide phase exists. The ratio was calculated. In the range of the photograph, the total length of the metal oxide phases was divided by the length of the inner conductor layer. Here, what penetrated the inner conductor layer was determined as a metal oxide phase. In addition, although the metal oxide phase was formed 15 to 20% in length ratio in the internal conductor layer obtained from the conductor pattern formed using the screen whose plate-making line width was about 30 micrometers, plate-making line width However, in the inner conductor layer obtained from the conductor pattern formed using a screen of about 20 μm, no metal oxide phase was found.

  The capacitance was measured at a temperature of 25 ° C., a frequency of 1.0 kHz, and a measurement voltage of 1 Vrms, and the average value was obtained. The number of samples was 30.

  Delamination was performed under two conditions after firing and after a thermal shock test. The thermal shock test used a method in which a capacitor was submerged in a solder bath heated to 350 ° C. for about 1 second. The delamination occurrence rate was obtained from 300 samples.

  In addition, a capacitor was manufactured by the same manufacturing method as described above from all the layers of the conductor pattern serving as the inner conductor layer of the laminated portion formed using a screen having a plate-making line width of about 20 μm or 30 μm. This was similarly evaluated as a sample of a comparative example (samples 1 and 5).

  As is clear from the results in Table 1, the samples in which the inner conductor layer in contact with the cover layer among the inner conductor layers has an oxide phase of the metal constituting the inner conductor layer (sample Nos. 2 to 4). ) Had a lower delamination rate than the sample (sample No. 1) having no metal oxide phase in the inner conductor layer.

  The sample in which the inner conductor layer having a metal oxide phase was provided over 10 layers from the cover layer side had an even lower rate of delamination.

  In all of these samples, the metal oxide phase penetrated the inner conductor layer in the thickness direction.

  In addition, although the delamination was not seen in the sample (sample No. 5) formed using a screen having a plate-making line width of about 30 μm in all layers of the laminated portion, the capacitance was greatly reduced.

DESCRIPTION OF SYMBOLS 1 ... Electronic component main body 3 ... External electrode 5 ... Ceramic insulator layer 7 ... Internal conductor layer 9 ... Laminate part 9a .. End surface 11 .... Cover layer 13 .... Metal oxide phase

Claims (4)

  In a multilayer electronic component having a laminated part in which ceramic insulator layers and internal conductor layers are alternately laminated in multiple layers, and a ceramic cover layer provided on each end face in the lamination direction of the laminated part, Among the internal conductor layers, the internal conductor layer that is in contact with the cover layer is formed so that the metal oxide phase constituting the internal conductor layer penetrates the internal conductor layer in the thickness direction. Characteristic multilayer electronic component.   2. The multilayer electronic component according to claim 1, wherein the inner conductor layer having the metal oxide phase is provided over a plurality of layers from the cover layer side.   3. The multilayer electronic component according to claim 1, wherein an average thickness of the inner conductor layer is thinner as it is closer to the cover layer side than a central portion in the stacking direction.   The average thickness of the inner conductor layer having the metal oxide phase is thinner than the average thickness of the inner conductor layer located at the center in the stacking direction. A laminated electronic component according to any one of the above.

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