CN1499545A - 介电陶瓷用原料粉末的制造方法、介电陶瓷及叠层陶瓷电容器 - Google Patents

介电陶瓷用原料粉末的制造方法、介电陶瓷及叠层陶瓷电容器 Download PDF

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CN1499545A
CN1499545A CNA2003101044403A CN200310104440A CN1499545A CN 1499545 A CN1499545 A CN 1499545A CN A2003101044403 A CNA2003101044403 A CN A2003101044403A CN 200310104440 A CN200310104440 A CN 200310104440A CN 1499545 A CN1499545 A CN 1499545A
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dielectric ceramic
high molecular
ceramic
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CN100373508C (zh
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v
吉川祐司
畠宏太郎
Ҳ
中村泰也
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Murata Manufacturing Co Ltd
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Abstract

一种介电陶瓷用原料粉末的制造方法、介电陶瓷及叠层陶瓷电容器，在BaCO3粉末等A元素的碳酸盐粉末上吸附有机高分子化合物，然后在该A元素的碳酸盐粉末中混合TiO2粉末等B元素的氧化物粉末，并将该混合粉末煅烧，得到了BaTiO3系的介电陶瓷用原料粉末。有机高分子化合物的作用是抑制在煅烧工序中A元素碳酸盐粉末的烧结和粒子生长。根据本发明，可提供微粒、组成均匀性优异的BaTiO3等ABO3系介质陶瓷原料粉末的制造方法。

Description

介电陶瓷用原料粉末的制造方法、介电陶瓷及叠层陶瓷电容器
技术领域
本发明涉及介电陶瓷用原料粉末的制造方法、由该制造方法得到的介电陶瓷、以及使用该介电陶瓷构成的叠层陶瓷电容器，特别涉及制造可实现叠层陶瓷电容器的介电陶瓷薄层化、微粒且组成均匀性优异的介电陶瓷用原料粉末的方法。
背景技术
叠层陶瓷电容器通常按照以下方法制造。
首先，准备表面上以所需图案赋予作为内部电极的导电材料的、含有介电陶瓷用原料粉末的陶瓷未加工片材。作为介电陶瓷用原料粉末，例如可使用具有BaTiO3组成的粉末。
然后，将包含上述被赋予导电材料的陶瓷未加工片材的多个陶瓷未加工片材层叠，热压接，从而得到被一体化的未加工叠层体。
接着，将该未加工叠层体烧成，得到烧结后的叠层体。在该叠层体的内部形成有由上述导电材料构成的内部电极。
接着，在叠层体的外表面上形成外部电极，且该外部电极与内部电极的特定物体电连接。外部电极例如是，通过向叠层体的外表面赋予含导电性金属粉末和玻璃粉的导电性糊膏，烘烤而形成。
由此，完成了陶瓷电容器。
但是，近年来，随着电子学技术的发展，电子部件的小型化发展迅速，而就叠层陶瓷电容器而言，小型化和大容量化的倾向也越来越显著。作为实现叠层陶瓷电容器的小型化和大容量化的有效方法，可以举出介电陶瓷层的薄层化。
为了实现介电陶瓷层的薄层化，重要的是将上述的介电陶瓷用原料粉末均匀化。例如，为了得到BaTiO3系的介电陶瓷用原料粉末，以往所采取的是，将BaCO3粉末和TiO2粉末混合，煅烧，发生固相反应，从而合成BaTiO3的方法。因此，若要通过上述这种固相反应制作出均匀的BaTiO3系介电陶瓷用原料粉末，最重要的就是，将BaCO3粉末和TiO2粉末尽可能均匀地分散。而为了均匀地分散BaCO3粉末和TiO2粉末，通常实施使这些粉末的比表面积变大或者使用介质进行分散的方法等伴随机械微粉碎的处理。
另外，在特开平7-118062号公报中记载了，将平均粒径0.5～1.4μm的BaCO3粉末和平均粒径0.5～1.1μm的TiO2粉末，与阴离子性有机系分散剂一同混合的BaTiO3系半导体陶瓷组合物的制造方法。根据该专利文献1，通过混合时添加阴离子性有机系分散剂，发挥出可均匀地混合BaCO3粉末和TiO2粉末微粒且可避免它们之间凝聚的效果。
但是，如上所述，即使被微粒化的BaCO3粉末和TiO2粉末均匀地分散，但在由BaCO3粉末和TiO2合成BaTiO3的煅烧工序中，BaCO3粒子容易生长，因此在与TiO2进行反应之前BaCO3粒子已经生长，从而出现很难与TiO2进行均匀反应的问题。
此外，上述说明是对作为介电陶瓷用原料粉末使用BaTiO3系原料粉末的例子进行的，但在通过将A元素的碳酸盐粉末和B元素的氧化物粉末混合、煅烧而合成ABO3的具有用通式ABO3(A是Ba、Ca、Sr和Mg的至少一种，B是Ti和Zr的至少一种)表示的组成的介电陶瓷用原料粉末的制造方法中，都会遇到上述问题。
发明内容
本发明的目的在于提供一种可解决上述这样问题的介电陶瓷用原料粉末的制造方法、通过该制造方法得到的介电陶瓷、以及使用该介电陶瓷构成的叠层陶瓷电容器。
首先，本发明提供一种，具有用通式ABO3(A是Ba、Ca、Sr和Mg的至少一种，B是Ti和Zr的至少一种)表示的组成的介电陶瓷用原料粉末的制造方法，为了解决上述的技术问题，其特征在于具备下面的结构。
即，在本发明的介电陶瓷用原料粉末的制造方法中，首先，在上述A元素的碳酸盐粉末上吸附有机高分子化合物，由此实施制得吸附有有机高分子的碳酸盐粉末的工序。然后，混合上述吸附有有机高分子的碳酸盐粉末和上述B元素的氧化物粉末，由此进行制得混合粉末的工序。接着，进行煅烧该混合粉末的工序，得到介电陶瓷用原料粉末。
如上述，在A元素的碳酸盐粉末上吸附有机高分子化合物时，优选进行以下2个工序，即，制得将A元素的碳酸盐粉末分散在含有有机高分子化合物的溶液中的料浆的工序；和从该料浆中除去含在上述溶液中的溶剂，制得有机高分子化合物吸附在其表面上的、吸附有有机高分子的碳酸盐粉末的工序。
此外，用于本发明介电陶瓷用原料粉末制造方法中的有机高分子化合物的分子量，优选在1000～100000的范围。
并且，作为碳酸盐粉末，可有效地利用比表面积在10m2/g以上的BaCO3粉末。另外，有机高分子化合物对于碳酸盐粉末的吸附量优选在0.1～5.0重量％的范围。
本发明还提供将通过上述制造方法制得的介电陶瓷用原料粉末成形、烧成得到的介电陶瓷。
本发明还提供使用上述介电陶瓷构成的叠层陶瓷电容器。
本发明的叠层电容器，其特征在于具有：包含多个被层叠的介电陶瓷层和沿着介电陶瓷层之间的特定界面形成的内部电极的叠层体；和形成在叠层体外表面上以与内部电极的特定物体电连接的外部电极，且介电陶瓷层是由上述介电陶瓷构成。
另外，本发明提供具备以下工序的介电陶瓷的制造方法，即，在上述A元素(其中，A是Ba、Ca、Sr和Mg中的至少一种元素)的碳酸盐粉末上吸附有机高分子化合物，制得吸附有有机高分子的碳酸盐粉末的工序；混合上述吸附有有机高分子化合物的碳酸盐粉末和B元素(其中，B是Ti和Zr中的至少一种元素)的氧化物粉末，制得混合粉末的工序；煅烧上述混合粉末，得到具有用通式ABO3表示的组成的介电陶瓷用原料粉末的工序；在上述介电陶瓷用原料粉末中加入粘合剂和溶剂，调制陶瓷料浆的工序；成形上述陶瓷料浆，制作未烧成的介电陶瓷成形体的工序；以及烧成上述未烧成的介电陶瓷成形体的工序。
另外，本发明提供具有以下工序的叠层陶瓷电容器的制造方法，即，在上述A元素(其中，A是Ba、Ca、Sr和Mg中的至少一种元素)的碳酸盐粉末上吸附有机高分子化合物，制得吸附有有机高分子的碳酸盐粉末的工序；混合上述吸附有有机高分子化合物的碳酸盐粉末和B元素(其中，B是Ti和Zr中的至少一种元素)的氧化物粉末，制得混合粉末的工序；煅烧上述混合粉末，得到具有用通式ABO3表示的组成的介电陶瓷用原料粉末的工序；在上述介电陶瓷用原料粉末中加入粘合剂和溶剂，调制陶瓷料浆的工序；制作未烧成陶瓷叠层体的工序，其中该陶瓷叠层体包括成形上述陶瓷料浆而制得的多个未烧成陶瓷层和沿着特定的界面形成的内部电极；以及烧成上述未烧成介电陶瓷叠层体的工序。
附图说明
图1是以图解方式表示本发明一个实施方式的叠层陶瓷电容器1的截面图。
图中：1-叠层陶瓷电容器，2-叠层体，3-介电陶瓷层，4，5-内部电极，8，9-外部电极。
具体实施方式
叠层陶瓷电容器1具有叠层体2。叠层体2由被层叠的多个介电陶瓷层3和沿着多个介电陶瓷层3之间的特定多个界面分别形成的多个内部电极4和5构成。内部电极4和5一直形成到叠层体2的外表面，且被引出到叠层体2的一端面6的内部电极4和被引出到另一端面7的内部电极5，在叠层体2的内部交替配置。
在叠层体2的外表面，于端面6和端面7上分别形成有外部电极8和9。并且，在外部电极8和9上面分别形成由镍、铜等形成的第一镀层10和11，进而在之上分别形成有由焊锡、锡形成的第二镀层12和13。
在这种叠层陶瓷电容器1中，介电陶瓷层3是通过烧成未加工陶瓷片材而制得，其中该未加工片材是通过成形例如含BaTiO3等组成用通式ABO3(A是Ba、Ca、Sr和Mg中的至少一种、B是Ti和Zr的至少一种)表示的介电陶瓷用原料粉末的陶瓷料浆而制得，且上述介电陶瓷用原料粉末可按照下述方法制造。
首先，在上述A元素的碳酸盐粉末上吸附有机高分子化合物，进行制得吸附有有机高分子的碳酸盐粉末的工序。在进行该工序时，优选例如，首先制得将A元素的碳酸盐粉末分散在有机高分子化合物中的料浆，然后通过干燥等从该料浆中除去含在上述溶液中的溶剂，制得有机高分子化合物吸附在其表面上的、吸附有有机高分子的碳酸盐粉末。接着，根据需要对吸附有有机高分子的碳酸盐粉末进行热处理。
接着，混合上述吸附有有机高分子化合物的碳酸盐粉末和上述B元素的氧化物粉末，进行制得混合粉末的工序。然后，进行煅烧该混合粉末的工序，制得介电陶瓷用原料粉末。
根据这种制造方法，由于作为A元素碳酸盐粉末使用了吸附有有机高分子的碳酸盐粉末，所以在煅烧工序中A元素碳酸盐粉末的烧结和粒子生长可以得到抑制。因此，可以在维持A元素碳酸盐粉末的微粒状态的同时，在使A元素碳酸盐和B元素氧化物均匀分散的状态下促进煅烧，其结果是可得到微粒且组成均匀性优异的ABO3系的介电陶瓷用原料粉末。
对于上述有机高分子化合物的吸附量，没有特别的限定，如果吸附量过少，就得不到所定的效果，相反，如果吸附量过多，则为了使有机物充分地热分解而需要精密控制热处理曲线等，有可能导致生产成本的上升。考虑这些因素，有机高分子化合物的吸附量为0.1～5.0重量％，更优选的是在0.3～2.0重量％范围内选择。
另外，使用的有机高分子化合物的分子量，优选在1000～100000范围。若分子量小于1000，则在合成ABO3时，有机高分子化合物在发挥出其效果之前已被分解掉；相反，若分子量超过100000，则热分解难，烧结后的介电陶瓷中残留的碳量变多，会对叠层陶瓷电容器1的特性带来坏的影响。另外，有机高分子化合物优选具有羧基、乙烯基、丙烯基、环氧基中的至少一种官能基。如果有机高分子化合物的分子量在上述范围且该有机高分子化合物具备上述的官能基，则有机高分子化合物将有效地吸附在碳酸盐粉末上，可更有效地抑制在煅烧工序中碳酸盐粉末的烧结和粒子的生长。
希望制得BaTiO3系介电陶瓷用原料粉末时，通常使用BaCO3粉末作为A元素的碳酸盐粉末，并使用TiO2粉末作为B元素的氧化物粉末，其中BaCO3粉末的比表面积优选在10m2/g以上。通过使比表面积在10m2/g以上，可将使由上述有机高分子化合物产生的效果更加显著。BaCO3粉末的比表面积，优选是10～80m2/g，更优选是10～40m2/g。
即，在制作上述介电陶瓷用原料粉末时特别优选的是，比表面积为10m2/g以上、在其表面上吸附有分子量为1000～100000的有机高分子化合物、且上述有机高分子化合物对于上述碳酸盐粉末的吸附量在0.1～5.0重量％的、Ba、Ca、Sr和Mg中的至少一种的碳酸盐粉末。
接着，说明使用按照上述方法制造的介电陶瓷用原料粉末来实施的图1所示的叠层陶瓷电容器1的制造方法。
首先，在按照上述方法得到的介电陶瓷用原料粉末中添加有机粘合剂和溶剂，进行混合，调制出陶瓷料浆，然后将该陶瓷料浆成形为片材，制得由介电陶瓷层3构成的陶瓷未加工片材，即未烧成的介电陶瓷成形体。并且，根据需要，在陶瓷料浆中有时添加稀土类元素、Mn、烧结助剂等。
接着，在特定的陶瓷未加工片材上例如通过丝网印刷，形成作为内部电极4或5的导电性糊膜。
接着，将包括按照上述方法形成了导电性糊膜的陶瓷未加工片材的多个陶瓷未加工片材层叠，热压接之后，根据需要切断。这样，可得到具有以下结构的未烧成陶瓷叠层体，即，层叠多个陶瓷未加工片材和沿着陶瓷未加工片材之间的特定界面分别形成的作为内部电极4和5的导电性糊膜的结构。在该未烧成陶瓷叠层体中，导电性糊膜将其端部露出在某一个端面上。
接着，烧成未烧成的陶瓷叠层体。从而可得到如图1所示的烧结后的叠层体2。在该叠层体2中，由上述陶瓷未加工片材构成介电陶瓷层3，并且由导电性糊膜构成内部电极4或5。
然后，分别在叠层体2的端面6和7上涂布导电性糊膏，使其分别与内部电极4和5的被露出的各端缘电连接，然后烘烤，形成外部电极8和9。
接着，根据需要在外部电极8和9上镀镍、铜等，形成第一镀层10和11。并且，通过在该第一镀层10和11上镀焊锡、锡等，形成第二镀层12和13。
由以上方法完成叠层陶瓷电容器1。
在这样得到的叠层陶瓷电容器1中，构成介电陶瓷层3的介电陶瓷，由于其原料可维持微粒和组成的均匀性，所以处于结晶粒径小且粒径分布也窄的状态。因而，可使由结晶粒径的偏差而引起的叠层陶瓷电容器1电特性偏差小。介电陶瓷层3的厚度越薄、介电陶瓷层3的层叠数越多，这种效果将更加显著，所以可有助于叠层陶瓷电容器1的小型化和大容量化。
下面，对于为了确认本发明效果而实施的实验例进行说明。
【实验例】
1、介电陶瓷用原料粉末的制作实验
(实施例1)
作为起始原料，分别称量吸附了0.8重量％的分子量约21000的聚乙烯丁缩醛系有机高分子化合物的、比表面积为18m2/g的BaCO3粉末，和比表面积为20m2/g的TiO2粉末，使Ba/Ti的摩尔比为1.000，然后将这些湿式混合。接着，干燥该混合粉末，再于间歇炉中，在1100℃温度下煅烧2小时。最后，将得到的煅烧物用干式粉碎机粉碎，得到了钛酸钡系的介电陶瓷用原料粉末。
(比较例1)
除了作为起始原料，使用了未吸附聚乙烯丁缩醛系有机高分子化合物的BaCO3粉末以外，在与实施例1相同的条件下得到了钛酸钡系的介电陶瓷用原料粉末。
(实施例2)
作为起始原料，分别称量吸附了1.3重量％的分子量约10000的聚羧酸铵盐系有机高分子化合物的、比表面积为12m2/g的BaCO3粉末，和比表面积为10m2/g的TiO2粉末，使Ba/Ti的摩尔比为1.000，然后将这些湿式混合。接着，干燥该混合粉末，再于间歇炉中，在1100℃温度下煅烧2小时。最后，将得到的煅烧物用干式粉碎机粉碎，得到了钛酸钡系的介电陶瓷用原料粉末。
(比较例2)
除了作为起始原料，使用了未吸附聚羧酸铵盐系有机高分子化合物的BaCO3粉末以外，在与实施例2相同的条件下得到了钛酸钡系的介电陶瓷用原料粉末。
(实施例3)
作为起始原料，分别称量吸附了1重量％的分子量约15000的苯乙烯—马来酸酐共聚型高分子表面活性剂的、比表面积为25m2/g的BaCO3粉末，同样是吸附了1重量％苯乙烯—马来酸酐共聚型高分子表面活性剂的、比表面积为30m2/g的CaCO3粉末，和比表面积为15m2/g的TiO2粉末，使它们的摩尔比为(Ba0.95Ca0.05)1.000TiO3，然后将这些湿式混合。接着，干燥该混合粉末，再于间歇炉中，在1100℃温度下煅烧2小时。最后，将得到的煅烧物用干式粉碎机粉碎，得到了Ca改性钛酸钡系的介电陶瓷用原料粉末。
(比较例3)
除了作为起始原料，使用了未吸附高分子表面活性剂的BaCO3粉末和CaCO3粉末以外，在与实施例3相同的条件下得到了Ca改性钛酸钡系的介电陶瓷用原料粉末。
(实施例4)
作为起始原料，分别称量吸附了0.9重量％分子量约7000的环氧树脂的、比表面积为5m2/g的CaCO3粉末，和比表面积为31m2/g的ZrO2粉末，使Ca/Zr摩尔比为0.999，将这些湿式混合。接着，干燥该混合粉末，再于间歇炉中，在1200℃温度下煅烧2小时。最后，将得到的煅烧物用干式粉碎机粉碎，得到了锆酸钙系的介电陶瓷用原料粉末。
(比较例4)
除了作为起始原料，使用了未吸附环氧树脂的CaCO3粉末以外，在与实施例4相同的条件下得到了锆酸钙系的介电陶瓷用原料粉末。
(实施例5)
作为起始原料，分别称量吸附了1.1重量％分子量约9000的聚甲基丙烯酸甲酯的、比表面积为19m2/g的BaCO3粉末，同样是吸附了1.1重量％聚甲基丙烯酸甲酯的比表面积为30m2/g的CaCO3粉末，比表面积为33m2/g的ZrO2粉末，和比表面积为20m2/g的TiO2粉末，使摩尔比成为(Ba0.92Ca0.08)1.001(Zr0.2Ti0.8)O3，然后将它们湿式混合。接着，干燥该混合粉末，再于间歇炉中，在1150℃温度下煅烧2小时。最后，将得到的煅烧物用干式粉碎机粉碎，得到了Ca改性锆酸钛酸钡系的介电陶瓷用原料粉末。
(比较例5)
除了作为起始原料，使用了未吸附聚甲基丙烯酸甲酯的BaCO3粉末和CaCO3粉末以外，在与实施例5相同的条件下得到了Ca改性锆酸钛酸钡系的介电陶瓷用原料粉末。
(实施例6)
除了作为起始原料，使用吸附了1.3重量％分子量约10000的聚羧酸铵系有机高分子化合物的、比表面积为6m2/g的BaCO3粉末以外，在与实施例2相同的条件下，得到了钛酸钡系的介电陶瓷用原料粉末。
(评价)
对于按照上述方法得到的实施例1～6和比较例1～5的各介电陶瓷用原料粉末，如表1所示，分别求出比表面积(SS)、粒度分布(D90)和摩尔比偏差。
其中，根据BET法求得比表面积(SS)。使用激光衍射粒度分布测定器求出粒度分布(D90)。利用TEM测定10个原始粒子的摩尔比，用其最大值和最小值的差来表示摩尔比偏差。
表1
 SS(m2/g) D90(μm) 摩尔比偏差
实施例1  5.80  0.78  0.007
比较例1  4.51  1.02  0.015
实施例2  5.13  0.82  0.005
比较例2  4.03  1.13  0.011
实施例3  4.88  0.85  0.005
比较例3  3.54  2.07  0.015
实施例4  6.82  0.96  0.008
比较例4  5.77  1.35  0.020
实施例5  6.13  0.88  0.007
比较例5  5.33  1.21  0.025
实施例6  4.91  0.95  0.009
由表1可知，作为起始原料使用了附着有有机高分子化合物的碳酸盐粉末的实施例1～6，与使用未吸附有如上述这样的有机高分子化合物的碳酸盐粉末的比较例1～5相比，所得介电陶瓷用原料粉末的粒度分布(D90)或摩尔比偏差得到改善，可得到微粒且均匀的介电陶瓷用原料粉末。
另外，若比较仅是起始原料BaCO3粉末的比表面积不同的实施例2和实施例6，可知比表面积为10m2/g以上的实施例2比比表面积小于10m2/g的实施例6，上述效果更显著。
2.叠层陶瓷电容器的制作实验
(实施例)
在上述实施例1中制作的钛酸钡系介电陶瓷用原料粉末中，添加稀土类元素、Mn和烧结助剂，将组成调整为使该原料粉末的容量温度特性满足EIA规格的X7R特性，随后加入聚乙烯丁缩醛系粘合剂和乙醇等有机溶剂，使用球磨机实施湿式混合，制作了陶瓷料浆。
然后，利用照相凹板式涂敷法，将陶瓷料浆成形为烧结后的介电陶瓷层的厚度达到2.5μm的片材状，得到了陶瓷未加工片。
接着，在陶瓷未加工片材上丝网印刷作为导电成分含有镍的导电性糊膏，形成了作为内部电极的导电性糊膜。
接着，层叠包括形成了导电性糊膜的陶瓷未加工片材的多个陶瓷未加工片材，并使导电性糊膜被引出的侧互不相同，得到了未加工叠层体。
接着，将未加工叠层体加热至280℃，使粘合剂燃烧之后，在由H2-N2-H2O气体构成的还原性气氛中，在1200℃温度烧成2小时，得到了烧结后的叠层体。
接着，在层叠体的两端面上涂布含B2O3-Li2O-SiO2-BaO系玻璃粉的以银作为导电成分的导电性糊膏，在氮气氛下用800℃的温度烘烤，形成了与内部电极电连接的外部电极。
这样，得到了夹在内部电极之间的介电陶瓷层为5层，其厚度为2.5μm且每层的对向电极面积为2.85mm2的实施例叠层陶瓷电容器。
(比较例)
除使用了在上述比较例1中制作的钛酸钡系的介电陶瓷用原料粉末以外，在与上述实施例相同的条件下得到了比较例叠层陶瓷电容器。
(评价)
对于按照上述方法得到的实施例和比较例的叠层陶瓷电容器，如表2所示测定了室温下的介电常数(ε)和绝缘电阻(logIR)。
另外，介电常数(ε)是，由使用LCR测定仪在1kHz和0.5Vrmz条件下测定的静电电容算出的值。此外，绝缘电阻(logIR)是，由外加6.3V电压120秒后测定的电阻值(Ω)测定的。对40个试样进行测定并求出其平均值和偏差(3CV)。其中，3CV是，用式3CV＝3×(σ/平均值)×100求出的值。
表2
        ε        Log1R
平均值 3CV(％) 平均值 3CV(％)
实施例 2030  2.0  11.3  0.5
比较例 2010  5.4  10.7  10.2
由表2可知，实施例与比较例相比，实施例叠层陶瓷电容器的电特性偏差小。由此可知，用于制作实施例叠层陶瓷电容器的上述实施例1的介电陶瓷用原料粉末，在烧成之后，可维持晶粒微小、粒度分布窄的状态。
发明效果
如上所述，根据本发明的介电陶瓷用原料粉末的制造方法，由于作为A元素的碳酸盐粉末使用了吸附有有机高分子化合物的粉末，所以在合成ABO3的煅烧工序中，可以抑制A元素碳酸盐粉末的烧结和粒子生长。因此，可维持A元素碳酸盐粉末的微粒状态，同时在A元素碳酸盐和B元素氧化物均匀分散的状态下促进煅烧，其结果，可得到粒子小、且组成均匀性优异的ABO3系的介电陶瓷用原料粉末。
如上所述，在A元素的碳酸盐粉末上吸附有机高分子化合物时，先制得将A元素的碳酸盐粉末分散在含有机高分子化合物的溶液中的料浆之后，再从该料浆中除去含在上述溶液中的溶剂，就可有效地得到表面上吸附有有机高分子化合物的吸附有有机高分子的碳酸盐粉末。
另外，若用于本发明介电陶瓷用原料粉末制造方法中的有机高分子化合物的分子量选自1000～100000的范围，则能够可靠地防止以下2种情况，即，可防止ABO3合成中，在发挥出有机高分子化合物的效果之前，该有机高分子化合物就分解掉，或者是有机高分子化合物难以分解，因此在烧成后的介电陶瓷中残留的碳量变多，对叠层陶瓷电容器等的电特性带来不好影响。
另外，在本发明的介电陶瓷用原料粉末的制造方法中，若使用比表面积为10m2/g以上的BaCO3粉末作为A元素的碳酸盐粉末，则能够更显著地发挥出上述有机高分子化合物所带来的效果。
本发明的介电陶瓷，由于是先成形按照上述制造方法得到的介电陶瓷用原料粉末之后再进行烧成而得，所以可维持原料粉末中的微粒和组成均匀性，从而可维持晶粒微小、粒度分布窄的状态。
因此，若使用上述介电陶瓷构成叠层陶瓷电容器，则可使由于结晶粒径的偏差而引起的电特性偏差小。而叠层陶瓷电容器中所具备的介电陶瓷层的厚度越薄、介电陶瓷层的层叠数越多，这种效果将更加显著，从而可有效地实现叠层陶瓷电容器的小型化和大容量化。

Claims (10)

1、一种介电陶瓷用原料粉末的制造方法，是具有用通式ABO3表示的组成的介电陶瓷用原料粉末的制造方法，且所述通式中A是Ba、Ca、Sr和Mg中的至少一种，B是Ti和Zr中的至少一种，其特征在于具有：在上述A元素的碳酸盐粉末上吸附有机高分子化合物，由此制得吸附有有机高分子的碳酸盐粉末的工序；混合上述吸附有有机高分子化合物的碳酸盐粉末和上述B元素的氧化物粉末，由此制得混合粉末的工序；以及煅烧上述混合粉末的工序。
2、根据权利要求1所述的介电陶瓷用原料粉末的制造方法，其特征在于在上述A元素的碳酸盐粉末上吸附有机高分子化合物的工序具有：制得上述A元素的碳酸盐粉末分散在含有上述有机高分子化合物的溶液中的料浆的工序；和从上述料浆中除去含在上述溶液中的溶剂，由此制得上述有机高分子化合物吸附在其表面上的、吸附有上述有机高分子的碳酸盐粉末的工序。
3、根据权利要求1所述的介电陶瓷用原料粉末的制造方法，其特征在于上述有机高分子化合物的分子量，在1000～100000的范围。
4、根据权利要求1所述的介电陶瓷用原料粉末的制造方法，其特征在于上述碳酸盐粉末是比表面积在10m2/g以上的BaCO3粉末。
5、根据权利要求1所述的介电陶瓷用原料粉末的制造方法，其特征在于上述有机高分子化合物对于上述碳酸盐粉末的吸附量为0.1～5.0重量％。
6、一种介电陶瓷的制造方法，其特征在于具有：在A元素的碳酸盐粉末上吸附有机高分子化合物，由此制得吸附有有机高分子的碳酸盐粉末的工序，其中A是Ba、Ca、Sr和Mg中的至少一种元素；
混合上述吸附有有机高分子化合物的碳酸盐粉末和B元素的氧化物粉末，由此制得混合粉末的工序，其中B是Ti和Zr中的至少一种元素；
煅烧上述混合粉末，得到具有用通式ABO3表示的组成的介电陶瓷用原料粉末的工序；
在上述介电陶瓷用原料粉末中加入粘合剂和溶剂，调制陶瓷料浆的工序；
成形上述陶瓷料浆，制作未烧成的介电陶瓷成形体的工序；
以及烧成上述未烧成的介电陶瓷成形体的工序。
7、一种叠层电陶瓷电容器的制造方法，其特征在于具有：在上述A元素的碳酸盐粉末上吸附有机高分子化合物，由此制得吸附有有机高分子的碳酸盐粉末的工序，其中A是Ba、Ca、Sr和Mg中的至少一种元素；
混合上述吸附有有机高分子化合物的碳酸盐粉末和B元素的氧化物粉末，由此制得混合粉末的工序，其中B是Ti和Zr中的至少一种元素；
煅烧上述混合粉末，得到具有用通式ABO3表示的组成的介电陶瓷用原料粉末的工序；
在上述介电陶瓷用原料粉末中加入粘合剂和溶剂，调制陶瓷料浆的工序；
制作未烧成陶瓷叠层体的工序，其中该陶瓷叠层体包括成形上述陶瓷料浆而制得的多个未烧成陶瓷层和沿着特定的界面形成的内部电极；
以及烧成上述未烧成介电陶瓷叠层体的工序。
8、一种介电陶瓷，其特征在于通过成形根据权利要求1～4中任意一项所述的制造方法制到的介电陶瓷用原料粉末，并将其烧成得到。
9、一种叠层陶瓷电容器，其特征在于具有：包含多个被层叠的介电陶瓷层和沿着所述介电陶瓷层之间的特定界面形成的内部电极的叠层体；
和形成在叠层体外表面上以与所述内部电极的特定物体电连接的外部电极，
且上述介电陶瓷层是由权利要求8所述的介电陶瓷构成。
10、一种碳酸盐粉末，是Ba、Ca、Sr和Mg中的至少一种的碳酸盐粉末，其特征在于比表面积为10m2/g以上，在其表面上吸附有分子量为1000～100000的有机高分子化合物，且上述有机高分子化合物对于上述碳酸盐粉末的吸附量为0.1～5.0重量％。
CNB2003101044403A 2002-10-30 2003-10-29 介电陶瓷用原料粉末的制造方法、介电陶瓷及叠层陶瓷电容器 Expired - Lifetime CN100373508C (zh)

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EP1415960B1 (en) 2012-07-25
JP3783678B2 (ja) 2006-06-07
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