JP2007115755A - Electronic component and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic component with reliability of electric connection which has an outer electrode having a structure where a second sintered electrode layer is laminated on a first sintered electrode layer, in which the first and second sintered electrode layers are precisely sintered and an appearance failure is difficult to occur. <P>SOLUTION: Outer electrodes 7 and 8 are provided with the first sintered electrode layers 7a and 8a and the second sintered electrode layers 7b and 8b. The first sintered electrode layers 7a and 8a comprise first borosilicate glass comprising alkali metal. When all elements except for boron are made to be 100 wt.%, first borosilicate glass comprises 85 to 95 wt.% of silicon, and 0.5 to 1.5 wt.% of alkali metal. The second sintered electrode layers 7b and 8b comprise second borosilicate glass comprising alkali metal. When all elements except for boron are made to be 100 wt.%, second borosilicate glass comprises 65 to 80 wt.% of silicon and 3.5 to 8.0 wt.% of alkali metal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electronic component in which external electrodes are formed on the outer surface of an electronic component main body and a method for manufacturing the same, and more specifically, an electronic component having a structure in which an external electrode is formed by laminating a plurality of sintered electrode layers, and the method It relates to a manufacturing method.

  Conventionally, when manufacturing an electronic component such as a multilayer ceramic capacitor, an external electrode is formed on the outer surface of the electronic component main body after the electronic component main body is manufactured. As this type of external electrode, an electrode having an Sn plating film or the like formed on the surface of a sintered electrode layer formed by baking a conductive paste has been widely used.

  On the other hand, in recent years, in order to achieve lead-free mounting, a method of mounting electronic components on a printed circuit board or the like with a conductive adhesive instead of solder has attracted attention. When an electronic component is mounted on a printed circuit board or the like with a conductive adhesive, the external electrode is bonded with the conductive adhesive. In this case, if the surface of the external electrode is formed of a Sn plating film or the like, the surface of the external electrode tends to be oxidized when the conductive adhesive is cured by heat treatment. As a result, there has been a problem that contact resistance increases or reliability of electrical connection decreases.

Therefore, Patent Document 1 below discloses an electronic component using an external electrode formed by laminating a plurality of sintered electrode layers instead of the Sn plating film. That is, in the multilayer ceramic electronic component described in Patent Document 1, the first sintered electrode layer mainly composed of Cu or Cu alloy is formed on both end faces of the multilayer ceramic body having an internal electrode made of Ni or Ni alloy. An external electrode is formed by laminating a second sintered electrode layer mainly composed of Ag or an Ag alloy. Here, first, a first conductive paste containing Cu or Cu alloy and glass frit is applied, and then glass frit is added to metal powder mainly composed of Ag or Ag—Pd alloy. The external electrode is formed by applying a conductive paste and then baking the first and second conductive pastes at 700 ° C. at the same time.
JP 2002-158137 A

  In the manufacturing method described in Patent Document 1, since the external electrode has a structure in which the first and second sintered electrode layers are laminated, the outer second sintered electrode layer is mainly made of Ag or an Ag alloy. Since it is a component, it is difficult to oxidize and is therefore suitable for mounting with conductive adhesive.

  However, the sintering temperature of Cu or Cu alloy that is the main component of the first sintered electrode layer is relatively higher than that of Ag or Ag alloy that is the main component metal of the second sintered electrode layer. Therefore, when the first and second sintered electrode layers are formed by co-firing, the sintering temperature of the main component metal is different as described above, so it is actually very difficult to control the sintering temperature and atmosphere. there were. Therefore, when the external electrode is formed by simultaneous firing, there is a problem that the denseness of one of the sintered electrode layers is not sufficient and the reliability tends to be lowered.

  An object of the present invention is an electronic component having an external electrode formed by laminating first and second sintered electrode layers, which solves the above-described drawbacks of the prior art, and includes the first and second sintered electrodes. An object of the present invention is to provide an electronic component having sufficient layer density and excellent reliability and a method for manufacturing the same.

  Another object of the present invention is to provide an electronic component suitable for mounting with a conductive adhesive and a method for manufacturing the same, in which the surface of the external electrode is hardly oxidized.

  An electronic component according to the present invention includes an electronic component main body and an external electrode formed on a surface of the electronic component main body, and the external electrode is on the first sintered electrode layer and the first sintered electrode layer. An electronic component having a second sintered electrode layer that is laminated and has a metal different from the first sintered electrode layer as a main component, wherein the first sintered electrode layer comprises an alkali metal. Containing the first borosilicate glass, and the first borosilicate glass contains an element having a characteristic X-ray energy of 1.043 keV or more as measured by a wavelength dispersive X-ray microanalyzer. When the content ratio is 100% by weight, silicon is contained in an amount of 85-95% by weight and alkali metal is contained in an amount of 0.5-1.5% by weight, and the second sintered electrode layer contains an alkali metal. 2 borosilicate glass, the second borosilicate system The glass has a value analyzed by a wavelength dispersive X-ray microanalyzer. When the content of an element having a characteristic X-ray energy of 1.043 keV or more is 100% by weight, silicon is 65 to 80% by weight, alkali The metal is contained in an amount of 3.5 to 8.0% by weight.

  In a specific aspect of the electronic component according to the present invention, the alkali metal contained in the first borosilicate glass is potassium, and the alkali metal contained in the second borosilicate glass is sodium.

  In still another specific aspect of the electronic component according to the present invention, the second sintered electrode layer contains a precious metal as a main component. As the noble metal, silver-palladium is preferably used.

  In still another specific aspect of the electronic component according to the present invention, the electronic component main body has an internal electrode, and the first sintered electrode layer is mainly composed of a metal alloyed with the internal electrode. In a more limited aspect of the electronic component of the present invention, the internal electrode is mainly composed of nickel, and the metal alloyed with the internal electrode is copper.

  In still another specific aspect of the electronic component according to the present invention, the external electrode of the electronic component is externally connected to the electrode pattern of the mounting substrate by a conductive adhesive in which a metal filler is dispersed in a resin. Electrode.

  The manufacturing method of the electronic component which concerns on this invention is equipped with the electronic component main body and the external electrode formed in the surface of an electronic component main body, The said external electrode is a 1st sintered electrode layer, and a 1st sintered electrode An electronic component having a second sintered electrode layer that is laminated on the layer and has a metal different from the first sintered electrode layer as a main component. A first conductive paste containing a first metal of the first and a first borosilicate glass containing an alkali metal having a first softening temperature is applied, and a first higher than the first softening temperature is applied. Forming a first sintered electrode layer by sintering at a sintering temperature, a second metal different from the first metal on the surface of the first sintered electrode layer, and the first A second borosilicate glass containing an alkali metal having a second softening temperature lower than the softening temperature of The second conductive paste is applied and sintered at a second sintering temperature lower than the first softening temperature and higher than the second softening temperature to form a second sintered electrode layer And a step of performing.

  In a specific aspect of the method for manufacturing an electronic component according to the present invention, the second metal is heated by the second borosilicate glass at the second sintering temperature lower than the melting temperature of the second metal. Sintering is performed, and the second sintering temperature is lower by 50 ° C. or more than the first softening temperature.

  In another specific aspect of the method for manufacturing an electronic component according to the present invention, the first metal is heated by the first borosilicate glass at a first sintering temperature lower than the melting temperature of the first metal. Sintered, the second metal is sintered by the second borosilicate glass at a second sintering temperature lower than the melting temperature of the second metal, and the first metal with respect to the melting temperature of the first metal. The temperature decrease width of the second sintering temperature relative to the melting temperature of the second metal is made larger than the temperature decrease width of the sintering temperature.

  In still another specific aspect of the method for manufacturing an electronic component according to the present invention, the alkali metal contained in the first borosilicate glass is potassium, and the second borosilicate glass contains. The alkali metal that is present is sodium.

  In still another specific aspect of the method for manufacturing an electronic component according to the present invention, the second metal is a noble metal. As the noble metal, silver-palladium is preferably used.

  In still another specific aspect of the method of manufacturing an electronic component according to the present invention, the electronic component main body has an internal electrode, and the first metal is a metal alloyed with the internal electrode.

  In still another specific aspect of the method for manufacturing an electronic component according to the present invention, the internal electrode contains nickel as a main component, and the metal alloyed with the internal electrode is copper.

  In the electronic component according to the present invention, the external electrode is formed by laminating the first and second sintered electrode layers on the surface of the electronic component main body. The first sintered electrode layer contains a first metal and a first borosilicate glass containing an alkali metal. The first borosilicate glass is a wavelength dispersion type X. The value analyzed by a ray microanalyzer, when the element having characteristic X-ray energy of 1.043 keV or more is 100% by weight, silicon is 85 to 95% by weight, and alkali metal is 0.5 to 1.5% by weight. % Composition. On the other hand, the second sintered electrode layer contains a second metal different from the first metal and a second borosilicate glass containing an alkali metal. Is a value analyzed by a wavelength dispersive X-ray microanalyzer. When the content of an element having a characteristic X-ray energy of 1.043 keV or more is 100% by weight, silicon is 65 to 80% by weight, an alkali metal Is contained in an amount of 3.5 to 8.0% by weight.

  Therefore, the second softening point of the second borosilicate glass contained in the second sintered electrode layer is the second softening point of the first borosilicate glass contained in the first sintered electrode layer. It becomes lower than the softening point of 1. Therefore, when the first sintered electrode layer and the second sintered electrode layer are separately sintered in this order, the second sintering temperature for obtaining the second sintered electrode layer is relatively low. Thus, the first borosilicate glass contained in the first sintered electrode layer is not softened during the sintering for obtaining the second sintered electrode layer. Accordingly, the first sintered electrode layer is sintered under conditions sufficient to obtain the first sintered electrode layer, and after forming the dense first sintered electrode layer, the second sintered electrode layer is formed. Even if the layer is formed, the first borosilicate glass in the first sintered electrode layer is not softened, so that an external electrode having dense first and second sintered electrode layers can be formed. it can.

  Therefore, according to the present invention, it is possible to effectively increase the reliability of the external electrode formed by laminating the first and second sintered electrode layers.

  When the alkali metal contained in the first borosilicate glass is potassium and the alkali metal contained in the second borosilicate glass is sodium, the second contains sodium. The second softening point of the borosilicate glass is surely made lower than the first softening point of the first borosilicate glass.

  When the second sintered electrode layer contains a noble metal as a main component, the noble metal such as Ag or an Ag alloy is hardly oxidized, so that the external electrode surface is hardly oxidized. Therefore, an electronic component suitable for mounting with a conductive adhesive can be provided. In particular, when a silver-palladium alloy is used as the noble metal, an external electrode having excellent conductivity and excellent oxidation resistance can be formed.

  When the electronic component main body has an internal electrode and the first sintered electrode layer is mainly composed of a metal alloyed with the internal electrode, the electrical connection between the first sintered electrode layer and the internal electrode Reliability can be improved and bonding strength can be improved.

  When the internal electrode is mainly composed of nickel and the metal alloyed with the internal electrode is copper, the reliability of the electrical connection between the first sintered electrode layer and the internal electrode is obtained by alloying nickel and copper. It is possible to improve the properties and the bonding strength.

  When the external electrode of the electronic component is connected to the electrode pattern of the mounting substrate with a conductive adhesive in which a metal filler is dispersed in a resin, the external electrode is externally connected to the second sintered body. Since it has an electrode layer, it has excellent oxidation resistance unlike an Sn plating film. Therefore, the external electrode can be reliably connected to the electrode pattern by the conductive adhesive.

  In the method for manufacturing an electronic component according to the present invention, the first conductive paste containing the first metal and the first borosilicate glass having the first softening temperature is applied, and the first softening temperature is applied. The first sintered electrode layer is formed by sintering at a higher first sintering temperature, and then the second metal is formed on the first sintered electrode layer surface as a main component, A second conductive paste containing a second borosilicate glass having a second softening temperature lower than the softening temperature is applied, and is lower than the first softening temperature and higher than the second softening temperature. Sintering is performed at the second sintering temperature to form a second sintered electrode layer. Therefore, temperature control and atmosphere control are easier than in the case where the first and second sintered electrode layers are fired simultaneously. In addition, the denseness of each of the first sintered electrode layer and the second sintered electrode layer is also improved.

  That is, in the manufacturing method described in Patent Document 1 described above, since the first and second sintered electrode layers are obtained by simultaneous firing, it is actually difficult to control temperature and atmosphere during sintering. It was difficult to make both the first and second sintered electrode layers dense.

  On the other hand, in the manufacturing method according to the present invention, since the first sintered electrode layer and the second sintered electrode layer are sintered in different processes, the atmosphere control of each sintering process is performed independently. Thus, a dense first sintered electrode layer and second sintered electrode layer can be formed.

  In addition, in the manufacturing method according to the present invention, the second sintering temperature when forming the second sintered electrode layer is lower than the first softening temperature and higher than the second softening temperature. ing. Therefore, in the step of forming the second sintered electrode layer, the first borosilicate glass in the first sintered electrode layer that has been sintered is not softened. Therefore, after the second sintered electrode layer is formed, defects due to the deformation of the glass component in the first sintered electrode layer are unlikely to occur, so that an electronic component with even higher reliability is reliably provided. It becomes possible.

  The second metal is sintered by the second borosilicate glass at a second sintering temperature lower than the melting temperature of the second metal, and the second sintering temperature is higher than the first softening temperature. When the temperature is lower by 50 ° C. or more, according to the present invention, it is possible to provide an electronic component in which external electrode defects are less likely to occur.

  The first metal is sintered by the first borosilicate glass at a sintering temperature lower than the melting temperature of the first metal, and the second metal is dissolved by the second borosilicate glass. The second sintering is performed at a second sintering temperature lower than the temperature, and the second sintering with respect to the melting temperature of the second metal as compared with the temperature decrease range of the first sintering temperature with respect to the melting temperature of the first metal. When the temperature decrease width of the temperature is increased, deformation of the first borosilicate glass of the first sintered electrode layer is less likely to occur in the step of obtaining the second sintered electrode layer, and The denseness of the first and second sintered electrode layers can be further effectively improved.

  When the alkali metal contained in the first borosilicate glass is potassium and the alkali metal contained in the second borosilicate glass is sodium, the second borosilicate The second softening temperature of the glass is lowered.

  When the second metal is a noble metal, the surface of the second sintered electrode layer is difficult to oxidize. Therefore, an electronic component suitable for mounting with a conductive adhesive can be provided according to the present invention. In the case where silver-palladium is used, the conductivity and oxidation resistance of the external electrode can be further enhanced.

  When the electronic component body has an internal electrode and the first metal is formed of a metal alloyed with the internal electrode, the reliability of electrical connection between the external electrode and the internal electrode can be improved. And improvement of the mechanical joint strength of both can be aimed at. In particular, when the internal electrode is mainly composed of nickel, when copper is used as a metal to be alloyed with the internal electrode, nickel and copper are surely alloyed, and the reliability of electrical connection between the internal electrode and the external electrode is improved. It can be effectively increased.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1 is a front sectional view showing a multilayer ceramic capacitor as an electronic component according to an embodiment of the present invention. The multilayer ceramic capacitor 1 has a ceramic sintered body 2. The ceramic sintered body 2 is made of an appropriate dielectric ceramic such as a barium titanate ceramic.

  Inside the ceramic sintered body 2, internal electrodes 3 to 6 are arranged so as to face each other with a ceramic layer interposed therebetween. The internal electrodes 3 and 5 are drawn out to the first end face 2a of the ceramic sintered body 2, and the internal electrodes 4 and 6 are drawn out to the second end face 2b opposite to the first end face 2a. Yes.

  In the present embodiment, the internal electrodes 3 to 6 are formed by baking a conductive paste containing Ni as a main component when firing the ceramic sintered body 2. Therefore, the internal electrodes 3 to 6 are mainly composed of Ni.

  External electrodes 7 and 8 are formed so as to cover the end faces 2a and 2b. The external electrodes 7 and 8 include first sintered electrode layers 7a and 8a and second sintered electrode layers 7b and 8b formed on the first sintered electrode layer. In the present embodiment, the first sintered electrode layers 7a and 8a are formed by baking a conductive paste containing Cu powder as the main component metal and the first borosilicate glass at the first sintering temperature. Is formed.

  The first borosilicate glass contains an alkali metal, and when analyzed by a wavelength dispersive X-ray microanalyzer, when the content ratio of elements having characteristic X-ray energy of 1.043 keV or more is 100% by weight The composition contains 85 to 95% by weight of silicon and 0.5 to 1.5% by weight of alkali metal.

  On the other hand, in this embodiment, the second sintered electrode layers 7b and 8b are made of a conductive paste containing Ag—Pd alloy powder as a main component metal and second borosilicate glass at a second sintering temperature. It is formed by baking.

  The second borosilicate glass contains an alkali metal, and when analyzed with a wavelength dispersive X-ray microanalyzer, the content of an element having a characteristic X-ray energy of 1.043 keV or more is 100% by weight. The composition contains 65 to 80% by weight of silicon and 3.5 to 8.0% by weight of alkali metal.

  The melting point of Cu is 1083 ° C., and the melting point of Ag—Pd used in this embodiment is about 960 to 1050 ° C. On the other hand, since the second borosilicate glass has a relatively high content of alkali metal compared to the first borosilicate glass, the second softening point is the softening point of the second borosilicate glass. It is made lower than the 1st softening point which is the point and the softening point of the 1st borosilicate type glass. That is, the first softening point of the first borosilicate glass is a temperature of about 760 to 810 ° C., and the second softening point of the second borosilicate glass is in the range of 580 to 630 ° C.

  Therefore, in obtaining the multilayer ceramic capacitor 1 of the present embodiment, the first sintering temperature is set to a temperature of about 860 to 910 ° C., and the first sintered electrode layers 7a and 8a are formed. The sintering temperature of 680 to 730 ° C., that is, a temperature lower than the first sintering temperature, forms the second sintered electrode layers 7b and 8b.

  As described above, the first sintering temperature is in the range of about 860-910 ° C., therefore Cu is lower than the melting point of Cu by the first borosilicate glass having the first softening point, Sintering is performed at a temperature higher than the first softening point, and dense first sintered electrode layers 7a and 8a are formed. And since the 2nd sintering temperature at the time of forming the 2nd sintered electrode layers 7b and 8b is made into the range of about 680-730 degreeC, the 2nd sintered electrode layers 7b and 8b are formed. At this time, the first borosilicate glass in the first sintered electrode layers 7a and 8a is not softened. Therefore, the second sintered electrode layers 7b and 8b can be formed without causing softening of the first borosilicate glass constituting the first sintered electrode layers 7a and 8a. Moreover, since the second softening point of the second borosilicate glass is 580 to 630 ° C., Ag—Pd can be densely sintered at a temperature lower than its melting point and higher than the second softening point. .

  The second metal is sintered at a second sintering temperature lower than the melting temperature of the second metal by the second borosilicate glass having the second softening temperature, and the second sintering temperature is the first sintering temperature. When the temperature is lower by 50 ° C. or more than the softening temperature, the softening of the first borosilicate glass in the first sintered electrode layer can be surely prevented when forming the second sintered electrode layer. ,preferable.

  In the manufacturing method of the present embodiment, the temperature reduction width of the first sintering electrode layer with respect to the melting temperature of Cu is 173 to 223 ° C., which is the second lower than the temperature reduction width. Since the temperature decrease range 230 to 280 ° C. of the second sintering temperature of the second sintered electrode layers 7b and 8b with respect to the melting temperature of the Ag—Pd alloy contained in the sintered electrode layer is increased. It is possible to make the second sintered electrode layer dense.

  In addition, when the second sintering temperature is lower than the first softening point of the first borosilicate glass, the first borosilicate glass is formed when the second sintered electrode layers 7b and 8b are formed. Softening results in the prevention portion 17c shown in FIG. FIG. 2 is a partially cutaway front cross-sectional view for explaining problems when the first and second sintered electrode layers are formed under conditions outside the scope of the second present invention. As shown in FIG. 2, the first and second sintered electrode layers 17 a and 17 b are formed on the outer surface of the ceramic sintered body 2, and here, a prevention portion 17 c is generated. The prevention portion 17c is a portion where the first borosilicate glass is softened and swollen when the second sintered electrode layer 17b is formed. As a result, the appearance of the external electrode 17 may be poor, or the reliability of the electrical connection between the first and second sintered electrode layers 17a and 17b may be impaired.

  On the other hand, in the manufacturing method of the multilayer ceramic capacitor 1 of the present embodiment, the first and second sintered electrode layers are sequentially formed at the first and second sintering temperatures, respectively. As described above, the first and second sintered electrode layers 7a, 8a, 7b, and 8b are densely sintered, and the multilayer ceramic capacitor 1 having excellent reliability can be provided. This will be described for a specific experimental example.

(First Experiment Example)
As the ceramic sintered body 2, a ceramic sintered body made of a barium titanate ceramic and having a length of 1.0 × width of 0.5 × thickness of 0.5 mm was prepared. The number of laminated internal electrodes was about 50, and the internal electrodes were made of Ni.

  First sintered electrode layers 7a and 8a were formed as a first layer so as to cover the end faces 2a and 2b of the ceramic sintered body 2 by applying and baking a Cu-containing conductive paste. As the Cu-containing conductive paste, a paste containing 15 parts by weight of the first borosilicate glass with respect to 100 parts by weight of the Cu powder and further having a solvent added to a solid ratio of 20% by volume was used. As the first borosilicate glass, when analyzed by a wavelength dispersive X-ray microanalyzer after sintering, when the content ratio of the element whose characteristic X-ray energy is 1.043 keV or more is 100% by weight, A composition containing 90% by weight of silicon and 1.0% by weight of potassium as an alkali metal was used. The glass softening point of the first borosilicate glass is about 790 ° C.

  The Cu conductive paste having the above composition was applied so that the film thickness after drying on the end faces 2a and 2b was 25 μm, and further applied so that the electrode cover dimension e in FIG. 1 was 50 μm. Thereafter, baking was carried out by maintaining the maximum temperature for 10 minutes in an atmosphere having an oxygen concentration of 0 to 5 ppm so that the maximum temperature was 850 ° C., thereby forming the first sintered electrode layers 7a and 8a.

  Next, in order to form the second sintered electrode layers 7b and 8b as the second layer, a conductive paste containing Ag—Pd powder was prepared. This conductive paste includes a powder made of an Ag—Pd alloy in which the ratio of Ag to Pd is 0.85: 0.15 by weight, the second borosilicate glass, and a solvent. A conductive paste was prepared. Here, the mixing ratio of the second borosilicate glass was 15 parts by weight with respect to 100 parts by weight of the Ag—Pd alloy powder. The solid content in the conductive paste was 20% by volume.

  As the second borosilicate glass, three types of borosilicate glasses having a second softening point of 804 ° C., 748 ° C., and 602 ° C. were prepared. When the three types of second borosilicate glasses were baked and analyzed by a wavelength dispersive X-ray microanalyzer, each had the following composition.

  (A) Second borosilicate glass having a softening point of 804 ° C. When the content ratio of elements having characteristic X-ray energy of 1.043 keV or more is 100% by weight, silicon is 90% by weight, sodium as an alkali metal 1.0 wt%.

  (B) Second borosilicate glass having a softening point of 748 ° C. When the content ratio of elements having characteristic X-ray energy of 1.043 keV or more is 100% by weight, silicon is 85% by weight and sodium is 2. 5% by weight.

  (C) Second borosilicate glass having a softening point of 602 ° C. When the content ratio of elements having characteristic X-ray energy of 1.043 keV or more is 100% by weight, silicon is 75% by weight and sodium is 5.0%. weight%.

  Further, when the Ag—Pd-containing conductive paste is applied onto the first sintered electrode layers 7a and 8a, the film thickness after drying is set to about 30 μm at the positions on the end faces 2a and 2b. The conductive paste was applied so that the electrode cover dimension E was about 250 μm.

  In the baking, the baking was performed in an atmosphere having an oxygen concentration of 0 to 5 ppm so that the maximum temperature was 600 ° C., 700 ° C., 800 ° C., or 900 ° C. and maintained at the maximum temperature for 10 minutes.

  As described above, the second sintered electrode layers 7b and 8b were formed by using the three types of second borosilicate glass and varying the sintering temperature. Appearance defects and reliability of the obtained multilayer ceramic capacitors were evaluated in the following manner.

  (1) Appearance defect: Observation of external electrodes with a stereomicroscope with a magnification of 3.5 times, whether blisters called blisters are formed on the surface, or whether there are partial peeling of external electrodes The number of monolithic ceramic capacitors that had poor appearance in 100 monolithic ceramic capacitors was determined. The results are shown in Table 1 below.

(2) Reliability Evaluation The insulation resistance logIR of the obtained multilayer ceramic capacitor is about 11. For each of the 50 multilayer ceramic capacitors, a power of 1 W was applied in an atmosphere of 70 ° C. and a relative humidity of 95%, and maintained for 500 hours to perform a moisture resistance load test. After this moisture resistance negative test, the insulation resistance was measured to determine the log IR, and a log IR of less than 6 was regarded as a poor reliability. Table 1 below shows the number of monolithic ceramic capacitors having poor reliability among the 50 monolithic ceramic capacitors.

  As is apparent from Table 1, the temperature at the time of baking the second sintered electrode layers 7b and 8b of the second layer, that is, the second sintering temperature is the first used for the first sintered electrode layers 7a and 8a. When the temperature was higher than the softening point of the borosilicate glass, an appearance defect occurred. Further, when the sintering temperature of the second sintered electrode layers 7b and 8b was lower than the second softening point of the second borosilicate glass, a reliability failure occurred.

  On the other hand, the softening point of the first borosilicate glass used for the first sintered electrode layers 7a and 8a is the second borosilicate type used for the second sintered electrode layer. If the second sintering temperature is higher than the softening point of the glass, lower than the softening point of the first borosilicate glass, and higher than the softening point of the second borosilicate glass, poor appearance and reliability It can be seen that no sexual defects occurred.

(Second experiment example)
Next, in the same manner as in the first experimental example, except for the second sintered electrode layers 7b and 8b, the second borosilicate glass having the composition (c) described above, that is, the softening point 602 ° C. For the first sintered electrode layers 7a and 8a, borosilicate glass having a softening point and a composition shown in Table 2 below was used. In the borosilicate glass used in the first layer, that is, the first sintered electrode layer in Table 2 below, when the total amount of elements having an X-ray energy of 1.043 keV or more is 100% by weight, silicon It shows that the composition contains Si and potassium K in the proportions (% by weight) shown in Table 2 below.

  The baking temperature of the first sintered electrode layers 7a and 8a was 860 ° C. as shown in Table 2 below.

  About each multilayer ceramic capacitor obtained by making it above, the external appearance defect and reliability were evaluated similarly to the case of the 1st experiment example mentioned above. The results are shown in Table 2 below.

  As is clear from the results of sample numbers 2-3 to 2-8 in Table 2, the softening point of the borosilicate glass used for the first sintered electrode layers 7a and 8a is 760 to 810 ° C., and the baking temperature is It can be seen that by setting the temperature at 860 ° C., it is possible to suppress the appearance failure and the reliability failure. Although the baking temperature is 860 ° C., it has been confirmed that the appearance defects and the reliability failures can be similarly suppressed in the range of 860 ° C. to 910 ° C.

  When the softening point of the glass used for the first sintered electrode layer is extremely lower than the baking temperature, for example, the baking temperature is 860 ° C., whereas the softening point is as in sample number 2-1. When the temperature is as low as about 732 ° C., the glass is easily fluidized. For this reason, the effect of promoting the metal sintering by glass has progressed too much, resulting in poor appearance.

  On the other hand, when the baking temperature is 860 ° C., but the softening point is 863 ° C. or 844 ° C. as in sample numbers 2-2 and 2-10, the glass does not flow sufficiently, and the metal is baked by the glass It is difficult to obtain an effect of promoting ligation. For this reason, defective products occurred at a considerable rate in the reliability failure.

  When the content ratio of potassium K in the glass in the first sintered electrode layer is too high as in sample number 2-9, the Si—Si bond in the glass is reduced and the chemical stability is lowered. Tend. Therefore, when K is added excessively, when exposed to a humid atmosphere, the glass may be melted and reliability may be liable to occur.

  Therefore, it is preferable that the addition ratio of K is 1.5 wt% or less when the content ratio of an element having a characteristic X-ray energy of 1.043 keV or more is 100 wt%.

(Third experimental example)
Next, as a third experimental example, as shown in Table 3 below, the composition of the borosilicate glass constituting the first sintered electrode layer is made constant, and the second sintered electrode layer 7b, A multilayer ceramic capacitor was produced and evaluated in the same manner as in the first and second experimental examples described above by changing the composition of the borosilicate glass constituting 8b. The results are shown in Table 3 below.

  In Table 3, the borosilicate glass constituting the first sintered electrode layers 7a and 8a is made of an element having a softening point of 787 ° C. and a characteristic X-ray energy of 1.043 keV or more. When the content ratio was 100 wt%, a composition containing 90 wt% Si and 1.0 wt% K was used, and the baking temperature was 860 ° C. On the other hand, the borosilicate glass used for the second sintered electrode layers 7b and 8b has a softening point in the range of 571 ° C. to 721 ° C. as shown in Table 3 below, and has characteristic X-ray energy. When the content ratio of the element of 1.043 keV or more is 100% by weight, Si and Na are used in the composition (% by weight) shown in Table 3 below, and the baking temperature is The temperature was 700 ° C.

  As is clear from Table 3, the sample numbers 3-3 to 3-8 in which the softening point of the glass used for the sintered electrode layer was set to 580 to 630 ° C. and the baking temperature was set to 680 to 730 ° C. It can be seen that the occurrence of defects and the occurrence of reliability failures can be suppressed simultaneously.

  On the other hand, in Sample No. 3-1, in which the glass softening point is lower than the baking temperature, the effect of promoting the metal sintering was excessive due to the flow of the glass, resulting in a large proportion of appearance defects.

  Further, when the softening point of the borosilicate glass used for the second sintered electrode layers 7b and 8b is near the baking temperature or higher than the baking temperature, as in sample number 3-10, Since the flow did not occur sufficiently and the effect of promoting metal sintering was difficult to obtain, poor reliability occurred.

  On the other hand, if the Na content ratio in the glass is too high, the ratio of Si bonds in the glass tends to decrease, and the chemical stability tends to decrease. Therefore, if the content ratio of Na is too large as in Sample No. 3-9, the glass dissolves when exposed to a humid atmosphere, and reliability is likely to occur. Therefore, it is preferable that Na is 8.0 wt% or less in the borosilicate glass used for the second sintered electrode layers 7b and 8b.

  In the above embodiment, the internal electrodes 3 to 6 are formed using Ni, and the first sintered electrode layers 7a and 8a contain Cu as a main component metal. Since Ni and Cu are easily alloyed, the reliability and bonding strength of the electrical connection between the internal electrode 3 to 6 and the sintered electrode layers 7a and 8a of the external electrodes 7 and 8 can be increased.

  In this embodiment, Cu is used as the main component metal of the first sintered electrode layers 7a and 8a. However, various metals other than Cu may be used as long as the metal is alloyed with Ni. it can.

  In addition, the internal electrode may be configured using a metal other than Ni. In this case, an appropriate metal that is alloyed with the metal configuring the internal electrode is used as the main component metal of the first sintered electrode layer. That's fine.

  In the above embodiment, the second sintered electrode layers 7b and 8b are made of an Ag—Pd alloy. However, other noble metals such as Ag may be the main component. When the second sintered electrode layers 7b and 8b are mainly composed of a noble metal, the surface is difficult to be oxidized, and therefore, the second sintered electrode layers 7b and 8b can be suitably used for an electronic component mounted with a conductive adhesive. That is, when mounting using a conductive adhesive obtained by filling a resin with a metal filler, the conductive adhesive is usually cured by heat treatment. By heating in this case, the second sintered electrode layers 7b and 8b containing the noble metal as a main component are hardly oxidized, so that the reliability of the mounting structure using the conductive adhesive can be improved.

  In the above embodiment, the alkali metal contained in the first borosilicate glass is potassium, and the alkali metal contained in the second borosilicate glass is sodium. In this case, since the second borosilicate glass containing sodium has a lower softening point than the first borosilicate glass containing potassium, the second borosilicate glass containing the second borosilicate glass according to the present invention is used. The second sintering temperature during baking of the sintered electrode layer can be reliably lowered. However, the alkali metal contained in the first and second borosilicate glasses is not limited to the combination of potassium and sodium.

  Furthermore, in the above embodiment, the multilayer ceramic capacitor 1 having the internal electrode has been described. However, the present invention can be applied to other multilayer ceramic electronic components other than the multilayer ceramic capacitor having the internal electrode. Furthermore, the electronic component according to the present invention may be an electronic component having no internal electrode. That is, the present invention can be applied to various electronic components such as an electronic component main body having no internal electrode, for example, a resistor in which a plurality of external electrodes are formed on the outer surface of a resistor chip.

1 is a front cross-sectional view showing a multilayer ceramic capacitor as an electronic component manufactured in an embodiment of the present invention. The partial notch front sectional drawing which shows a problem when the 1st sinter electrode layer in the 1st sintered electrode layer softens in the case of baking of the 2nd sintered electrode layer.

Explanation of symbols

1. Multilayer ceramic capacitor (electronic component)
2 ... Ceramic sintered bodies 2a, 2b ... First and second end faces 3-6 ... Internal electrodes 7, 8 ... External electrodes 7a, 8a ... First sintered electrode layers 7b, 8b ... Second sintered electrodes layer

Claims (15)

An electronic component body, and an external electrode formed on the surface of the electronic component body, wherein the external electrode is laminated on the first sintered electrode layer and the first sintered electrode layer; An electronic component having a second sintered electrode layer mainly composed of a metal different from the sintered electrode layer of
The first sintered electrode layer contains a first borosilicate glass containing an alkali metal, and the first borosilicate glass has a value analyzed by a wavelength dispersive X-ray microanalyzer. When the content ratio of elements whose characteristic X-ray energy is 1.043 keV or more is 100% by weight, 85 to 95% by weight of silicon and 0.5 to 1.5% by weight of alkali metal are included.
The second sintered electrode layer contains a second borosilicate glass containing an alkali metal, and the second borosilicate glass has a value analyzed by a wavelength dispersive X-ray microanalyzer. When the content ratio of elements having characteristic X-ray energy of 1.043 keV or more is 100% by weight, 65 to 80% by weight of silicon and 3.5 to 8.0% by weight of alkali metal are included. Electronic parts.   The electronic component according to claim 1, wherein the alkali metal contained in the first borosilicate glass is potassium, and the alkali metal contained in the second borosilicate glass is sodium.   The electronic component according to claim 1, wherein a main component metal of the second sintered electrode layer is a noble metal.   The electronic component according to claim 3, wherein the noble metal is silver-palladium.   5. The electronic component according to claim 1, wherein the electronic component main body has an internal electrode, and the first sintered electrode layer is mainly composed of a metal alloyed with the internal electrode. .   The electronic component according to claim 5, wherein the internal electrode is mainly composed of nickel, and the metal alloyed with the internal electrode is copper.   The external electrode of the said electronic component is an external electrode connected with the electroconductive adhesive formed by disperse | distributing a metal filler to resin with respect to the electrode pattern of a mounting board | substrate. The electronic component described. An electronic component body, and an external electrode formed on the surface of the electronic component body, wherein the external electrode is laminated on the first sintered electrode layer and the first sintered electrode layer; An electronic component having a second sintered electrode layer mainly composed of a metal different from the sintered electrode layer of
Applying a first conductive paste containing a first metal as a main component metal and a first borosilicate glass containing an alkali metal having a first softening temperature to the surface of the electronic component main body, Sintering at a first sintering temperature higher than the first softening temperature to form a first sintered electrode layer;
A second borosilicate containing a second metal different from the first metal and an alkali metal having a second softening temperature lower than the first softening temperature on a surface of the first sintered electrode layer And applying a second conductive paste containing glass and sintering at a second sintering temperature lower than the first softening temperature and higher than the second softening temperature. And a step of forming a connection electrode layer.   The second metal is sintered by the second borosilicate glass at the second sintering temperature that is lower than the melting temperature of the second metal, and the second sintering temperature is the first sintering temperature. The method for manufacturing an electronic component according to claim 8, wherein the temperature is lower by 50 ° C. or more than a softening temperature of the electronic component.   The first metal is sintered by the first borosilicate glass at a first sintering temperature lower than the melting temperature of the first metal, and the second metal is second borosilicate glass. The second metal is sintered at a second sintering temperature lower than the melting temperature of the second metal, and compared with the temperature decrease width of the first sintering temperature relative to the melting temperature of the first metal. The method for manufacturing an electronic component according to claim 8 or 9, wherein a temperature decrease width of the second sintering temperature with respect to the melting temperature is increased.   The alkali metal contained in the first borosilicate glass is potassium, and the alkali metal contained in the second borosilicate glass is sodium. The manufacturing method of the electronic component of description.   The method for manufacturing an electronic component according to claim 8, wherein the second metal is a noble metal.   The method for manufacturing an electronic component according to claim 12, wherein the noble metal is silver-palladium.   The method of manufacturing an electronic component according to any one of claims 7 to 13, wherein the electronic component main body has an internal electrode, and the first metal is a metal alloyed with the internal electrode.   The method for manufacturing an electronic component according to claim 14, wherein the internal electrode is mainly composed of nickel, and the metal alloyed with the internal electrode is copper.

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