JP2011003804A - Method for manufacturing porous valve metal anode body - Google Patents
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- 229910052751 metal Inorganic materials 0.000 title claims abstract description 91
- 239000002184 metal Substances 0.000 title claims abstract description 91
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 29
- 238000000034 method Methods 0.000 title abstract description 22
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 102
- 230000003647 oxidation Effects 0.000 claims abstract description 22
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 22
- 239000011888 foil Substances 0.000 claims abstract description 10
- 239000010949 copper Substances 0.000 claims description 26
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims description 25
- 229910052715 tantalum Inorganic materials 0.000 claims description 24
- 229910052802 copper Inorganic materials 0.000 claims description 17
- 239000008151 electrolyte solution Substances 0.000 claims description 17
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 16
- 239000010955 niobium Substances 0.000 claims description 16
- 239000007864 aqueous solution Substances 0.000 claims description 15
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 13
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 10
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 9
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 8
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 8
- 229910052758 niobium Inorganic materials 0.000 claims description 8
- 238000007743 anodising Methods 0.000 claims description 4
- 229910001257 Nb alloy Inorganic materials 0.000 claims description 3
- 229910001362 Ta alloys Inorganic materials 0.000 claims description 3
- 235000006408 oxalic acid Nutrition 0.000 claims description 3
- 239000003990 capacitor Substances 0.000 abstract description 16
- 125000005842 heteroatom Chemical group 0.000 abstract 3
- 239000010408 film Substances 0.000 description 65
- 239000000463 material Substances 0.000 description 16
- 238000010438 heat treatment Methods 0.000 description 13
- 238000005259 measurement Methods 0.000 description 13
- 230000015572 biosynthetic process Effects 0.000 description 11
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 7
- 238000004090 dissolution Methods 0.000 description 7
- 229910017604 nitric acid Inorganic materials 0.000 description 7
- 238000002048 anodisation reaction Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000008188 pellet Substances 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 238000009413 insulation Methods 0.000 description 3
- 238000004544 sputter deposition Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000010407 anodic oxide Substances 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000002912 waste gas Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000009751 slip forming Methods 0.000 description 1
- 238000005477 sputtering target Methods 0.000 description 1
- WTKKCYNZRWIVKL-UHFFFAOYSA-N tantalum Chemical compound [Ta+5] WTKKCYNZRWIVKL-UHFFFAOYSA-N 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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- Electrolytic Production Of Metals (AREA)
- Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
Abstract
Description
本発明は、固体電解コンデンサの陽極体などに用いられる多孔質バルブ金属陽極体、特に、タンタルまたはニオブからなる箔状の多孔質バルブ金属陽極体の製造方法に関する。 The present invention relates to a method for producing a porous valve metal anode body used for an anode body of a solid electrolytic capacitor, and more particularly a foil-like porous valve metal anode body made of tantalum or niobium.
タンタル電解コンデンサおよびニオブ電解コンデンサは、小型、大容量、および高信頼性という特徴を有し、携帯電話、ノートパソコンに代表される小型電子機器に必要不可欠な電子部品である。近年の電子機器の低背化、高機能化に伴い、これらの電解コンデンサにも、低背化と高容量化が強く求められている。 A tantalum electrolytic capacitor and a niobium electrolytic capacitor have characteristics of small size, large capacity, and high reliability, and are indispensable electronic components for small electronic devices typified by mobile phones and notebook computers. With the recent reduction in height and functionality of electronic devices, these electrolytic capacitors are also strongly required to have a low height and a high capacity.
従来のタンタル電解コンデンサおよびニオブ電解コンデンサでは、タンタルやニオブ粉末を圧粉および焼結することにより作製した多孔質ペレットを陽極体として用いているが、製法の本質上、陽極体の低背化には限界があり、得られる電解コンデンサの低背化にも、おのずと限界が生じている。また、陽極酸化の前工程となる多孔質ペレットの焼結は真空で行われ、焼結終了後に多孔質自体が空気雰囲気に晒されるため、陽極酸化前に多孔質ペレットに大気酸化皮膜がすでに形成されてしまっている。このため、処理後の誘電体皮膜が均質なものとならないという問題がある。 In conventional tantalum electrolytic capacitors and niobium electrolytic capacitors, porous pellets made by compacting and sintering tantalum and niobium powder are used as the anode body. However, there is a limit in reducing the height of the electrolytic capacitor obtained. In addition, porous pellets, which are the pre-process of anodic oxidation, are sintered in a vacuum, and the porous itself is exposed to the air atmosphere after sintering, so an atmospheric oxide film has already been formed on the porous pellets before anodic oxidation. It has been done. For this reason, there exists a problem that the dielectric film after a process does not become homogeneous.
これに対して、タンタル箔やニオブ箔の上に、バルブ金属と該バルブ金属と相溶性を持たない異相成分とからなる混合膜を、スパッタリングなどで成膜し、真空中または不活性ガス中で熱処理をして、その後、硝酸で溶解することにより異相成分のみを選択的に除去し、引き続いて電解により陽極酸化を行うことで、バルブ金属多孔質層を有する箔状のバルブ金属陽極体を製造する方法が特許文献１に記載されている。 On the other hand, a mixed film composed of a valve metal and a heterophasic component not compatible with the valve metal is formed on the tantalum foil or niobium foil by sputtering or the like, and is formed in a vacuum or in an inert gas. A foil-shaped valve metal anode body having a valve metal porous layer is manufactured by selectively removing only the heterogeneous components by heat treatment and then dissolving with nitric acid, followed by anodization by electrolysis. Japanese Patent Application Laid-Open No. H10-228561 describes a method for performing the above.
この方法により得られる箔状の多孔質バルブ金属陽極体により、電解コンデンサのさらなる低背化と高容量化が可能となり、電解コンデンサ用陽極体を製造するための有力な手段となるものである。 The foil-like porous valve metal anode body obtained by this method makes it possible to further reduce the height and capacity of the electrolytic capacitor, and is an effective means for producing an electrolytic capacitor anode body.
タンタル電解コンデンサおよびニオブ電解コンデンサにおいては、不純物の存在が陽極酸化皮膜の絶縁信頼性を損ねるため、従来の多孔質ペレットの場合、高純度タンタル粉末を用いている。同様の理由から、従来、バルブ金属多孔質層を有する箔状のバルブ金属陽極体の製造においても、異相成分を選択的に除去する工程において、硝酸を用いた酸洗浄という手段を採用している。 In the tantalum electrolytic capacitor and the niobium electrolytic capacitor, since the presence of impurities impairs the insulation reliability of the anodized film, high purity tantalum powder is used in the case of conventional porous pellets. For the same reason, conventionally, in the production of a foil-shaped valve metal anode body having a valve metal porous layer, a means of acid cleaning using nitric acid is employed in the step of selectively removing the heterogeneous components. .
ただし、硝酸による異相成分の除去の際に、窒素酸化物のガスが発生するため、廃ガス処理設備が必要となり、硝酸中に異相成分が溶解した廃液が発生するため、硝酸廃液の処理設備も必要となる。かかる廃ガス設備や廃液設備の必要性は、製造コストを上昇させる要因となっている。 However, when removing heterogeneous components with nitric acid, nitrogen oxide gas is generated, so a waste gas treatment facility is required, and a waste solution in which the heterogeneous components are dissolved in nitric acid is generated. Necessary. The necessity of such waste gas equipment and waste liquid equipment is a factor that increases the manufacturing cost.
本発明は、かかる問題点に鑑みてなされたものであって、電解コンデンサの低背化と高容量化を可能とする箔状の多孔質バルブ金属陽極体を、より低コストで作製するための手段を提供することを目的とする。 The present invention has been made in view of such problems, and is for producing a foil-like porous valve metal anode body capable of reducing the height and capacity of an electrolytic capacitor at a lower cost. It aims to provide a means.
本発明のバルブ金属陽極体の製造方法は、バルブ金属箔集電体の少なくとも一方の面に、バルブ金属と該バルブ金属と相溶性を持たない異相成分とからなる混合膜を形成し、得られた混合膜を熱処理し、該混合膜の異相成分を選択的に除去し、得られたバルブ金属多孔質層を陽極酸化して多孔質バルブ金属陽極体を得る工程からなる。 The method for producing a valve metal anode body of the present invention is obtained by forming a mixed film comprising a valve metal and a heterophasic component not compatible with the valve metal on at least one surface of the valve metal foil current collector. The mixed film is subjected to a heat treatment to selectively remove heterogeneous components of the mixed film, and the obtained valve metal porous layer is anodized to obtain a porous valve metal anode body.
特に、本発明では、前記異相成分の除去および前記バルブ金属多孔質層の陽極酸化をいずれも電解で行うことを特徴とする。 In particular, the present invention is characterized in that both the removal of the heterogeneous component and the anodic oxidation of the valve metal porous layer are carried out by electrolysis.
なお、本発明は、特に、前記バルブ金属およびバルブ金属箔集電体が、タンタル（Ｔａ）、ニオブ（Ｎｂ）、タンタル合金、およびニオブ合金のうちのいずれか一つから形成される、箔状の多孔質バルブ金属陽極体の製造に適用される。なお、バルブ金属とバルブ金属箔集電体は、上記材料から異なる材料を選択してもよいが、同じ材料を選択することが好ましい。 In the present invention, in particular, the valve metal and the valve metal foil current collector are formed of any one of tantalum (Ta), niobium (Nb), tantalum alloy, and niobium alloy. It is applied to the production of a porous valve metal anode body. In addition, although a different material may be selected from the said material for a valve metal and a valve metal foil collector, it is preferable to select the same material.
また、前記異相成分としては、銅を用いることが好ましい。 Moreover, it is preferable to use copper as the heterogeneous component.
前記電解において、電解液として、リン酸水溶液、シュウ酸水溶液、および硫酸水溶液のうちのいずれか一つを用い、電気伝導度を、３ｍＳ／ｃｍ以上５０ｍＳ／ｃｍ以下とすることが好ましい。 In the electrolysis, it is preferable that any one of a phosphoric acid aqueous solution, an oxalic acid aqueous solution, and a sulfuric acid aqueous solution is used as the electrolytic solution, and the electric conductivity is 3 mS / cm or more and 50 mS / cm or less.
前記電解において、前記異相成分の除去のための電解を行った後、引き続き、前記バルブ金属多孔質層の陽極酸化のための電解を行ってもよい。 In the electrolysis, after electrolysis for removing the heterogeneous component, electrolysis for anodic oxidation of the valve metal porous layer may be performed.
この場合、０．１Ｖ以上１０Ｖ以下の中から選ばれる電圧で定電圧電解を行った後、３Ｖ以上１００Ｖ以下の中から選ばれる電圧で定電圧電解を行うことが好ましい。 In this case, it is preferable to perform constant voltage electrolysis at a voltage selected from 3 V to 100 V after performing constant voltage electrolysis at a voltage selected from 0.1 V to 10 V.
もしくは、０．００１ｍＡ／μＦＶ以上０．１ｍＡ／μＦＶ以下の中から選ばれる電流密度で定電流電解を行った後、３Ｖ以上１００Ｖ以下の中から選ばれる電圧で定電圧電解を行うことが好ましい。 Alternatively, it is preferable to perform constant current electrolysis at a voltage selected from 3 V to 100 V after performing constant current electrolysis at a current density selected from 0.001 mA / μFV to 0.1 mA / μFV.
また、前記電解において、前記異相成分の除去のための電解と前記バルブ金属多孔質層の陽極酸化のための電解を同一工程で行ってもよい。 In the electrolysis, the electrolysis for removing the heterogeneous component and the electrolysis for anodic oxidation of the valve metal porous layer may be performed in the same step.
この場合、３Ｖ以上１００Ｖ以下の中から選ばれる電圧で定電圧電解を行うことが好ましい。 In this case, it is preferable to perform constant voltage electrolysis at a voltage selected from 3 V to 100 V.
本発明により、多孔質バルブ金属陽極体の製造において、低コストで多孔質バルブ金属陽極体を安定的に提供することが可能となる。よって、低背かつ高容量の電解コンデンサを低コストで供給することが可能となる。 The present invention makes it possible to stably provide a porous valve metal anode body at a low cost in the production of a porous valve metal anode body. Therefore, it is possible to supply a low-profile and high-capacity electrolytic capacitor at a low cost.
箔状の多孔質バルブ金属陽極体は、バルブ金属と該バルブ金属と相溶性を持たない異相成分とからなる混合膜を形成し、得られた混合膜を熱処理し、該混合膜の異相成分を除去し、得られたバルブ金属多孔質層を陽極酸化する工程を経て得られる。前述の通り、従来、陽極酸化皮膜の絶縁信頼性の観点より、異相成分を選択的に除去する工程において、硝酸を用いた酸洗浄という手段を採用している。 The foil-like porous valve metal anode body is formed with a mixed film composed of a valve metal and a heterophasic component that is not compatible with the valve metal, and the resulting mixed film is heat-treated to remove the heterophasic component of the mixed film. It is obtained through a step of removing and anodizing the obtained valve metal porous layer. As described above, conventionally, from the viewpoint of the insulation reliability of the anodized film, a means of acid cleaning using nitric acid is employed in the step of selectively removing the heterogeneous component.
本発明者らは、鋭意検討の結果、バルブ金属多孔質層の形成を、電解により混合膜から異相成分を除去することにより行うことで、陽極酸化皮膜の絶縁信頼性を損なうことなく、連続的若しくは同時的な電解工程により、異相成分の除去と得られたバルブ金属多孔質層の陽極酸化を実現でき、また、電解を所定条件に規制することで、バルブ金属多孔質層を損傷することなく多孔質バルブ金属陽極体を得ることができるとの知見を得て、本発明を完成したものである。 As a result of intensive studies, the inventors of the present invention continuously formed the valve metal porous layer by removing heterogeneous components from the mixed film by electrolysis, without impairing the insulation reliability of the anodized film. Or, by simultaneous electrolysis process, removal of heterogeneous components and anodic oxidation of the obtained valve metal porous layer can be realized, and electrolysis is regulated to a predetermined condition without damaging the valve metal porous layer. The present invention has been completed with the knowledge that a porous valve metal anode body can be obtained.
以下、バルブ金属としてタンタル（Ｔａ）を用いる場合について、熱処理された混合膜から異相成分を除去して多孔質膜を形成し、該多孔質膜を陽極酸化処理して誘電体皮膜を形成する工程について詳細に説明する。なお、ニオブ（Ｎｂ）、タンタル合金、ニオブ合金をバルブ金属として用いた場合も、同様の操作および処理を行うため、これらについては説明を省略する。 Hereinafter, in the case where tantalum (Ta) is used as the valve metal, a step of forming a porous film by removing heterogeneous components from the heat-treated mixed film, and forming a dielectric film by anodizing the porous film Will be described in detail. In addition, when niobium (Nb), a tantalum alloy, and a niobium alloy are used as a valve metal, the same operation and processing are performed, and thus description thereof is omitted.
（１）タンタルと異相成分とを混合成膜する工程
まず、タンタルと混じり合わない異相成分とを混合成膜する。混合成膜する手段としては、種々の手法が考えられるが、同時スパッタリング法または同時蒸着法を用いて、タンタルと異相成分を同時に混合成膜することが好ましい。これらの薄膜形成プロセスにおいては、原子あるいはクラスターレベルで飛来した物質が基材に付着することで薄膜が形成される。このため、タンタルと異相成分がナノオーダーで微細に混合された薄膜を、再現性よく容易に得ることができるためである。
(1) Step of forming a mixed film of tantalum and a different phase component First, a mixed film of a different phase component not mixed with tantalum is formed. Various means can be considered as a means for forming a mixed film, but it is preferable to simultaneously form a film of tantalum and a different phase component by using a simultaneous sputtering method or a simultaneous vapor deposition method. In these thin film formation processes, a thin film is formed by a substance flying at the atomic or cluster level adhering to the substrate. Therefore, a thin film in which tantalum and a different phase component are finely mixed in nano order can be easily obtained with good reproducibility.
成膜時の膜厚は、得ようとする多孔質層の厚さや表面積、すなわち目的とする静電容量を考慮して、任意に調節することが可能である。同じ成膜条件の場合、成膜面積に対する実際の表面積は、膜厚に比例して増加するため、膜厚を厚くすることにより、より大きな静電容量を得ることができる。 The film thickness at the time of film formation can be arbitrarily adjusted in consideration of the thickness and surface area of the porous layer to be obtained, that is, the target capacitance. In the case of the same film formation conditions, the actual surface area with respect to the film formation area increases in proportion to the film thickness, so that a larger capacitance can be obtained by increasing the film thickness.
混合膜におけるタンタルに対する異相成分の添加量は、体積比で３０％〜７０％の範囲となるようにすることが望ましい。異相成分を選択的に除去し、タンタルからなる多孔質層を得るためには、異相成分とタンタルがそれぞれ構造的につながっている必要がある。異相成分が体積比で３０％未満の場合、異相成分の構造的なつながりが悪くなり、引き続き行なわれる異相成分の除去工程で、異相成分が完全に除去されきれず、表面積の大きな多孔質構造が得られなくなる。一方、逆に、異相成分が体積比で７０％を超える場合、タンタルの構造的なつながりが悪くなり、得られる多孔質構造の強度が弱くなる。 The added amount of the heterophasic component with respect to tantalum in the mixed film is desirably in the range of 30% to 70% in volume ratio. In order to selectively remove the heterogeneous component and obtain a porous layer made of tantalum, the heterophasic component and tantalum must be structurally connected to each other. If the heterogeneous component is less than 30% by volume, the structural linkage of the heterogeneous component is deteriorated, and the heterogeneous component cannot be completely removed in the subsequent heterogeneous component removal step, resulting in a porous structure having a large surface area. It can no longer be obtained. On the other hand, if the heterogeneous component exceeds 70% by volume, the structural connection of tantalum is deteriorated and the strength of the resulting porous structure is weakened.
ただし、これはあくまでも目安であり、異相成分の添加量を制限するものではない。成膜方法によって異なる膜の配向の程度や、多孔質層の設計によっては、この範囲外の添加量を採用してもよい。 However, this is only a guide, and does not limit the amount of the heterophasic component added. Depending on the degree of orientation of the film, which differs depending on the film forming method, and the design of the porous layer, an addition amount outside this range may be employed.
成膜時のタンタルと異相成分の組成比は、最終的に得られる多孔質層の空隙率を考慮して決定する。本発明においては、選択的に除去可能な異相成分を用いているため、最終的に得られる多孔質層内部には異相成分は残留しない。したがって、異相成分が多いほど、空隙率の大きい多孔質電極箔が得られることになる。 The composition ratio between tantalum and the different phase component during film formation is determined in consideration of the porosity of the finally obtained porous layer. In the present invention, since the heterogeneous component that can be selectively removed is used, the heterophasic component does not remain in the finally obtained porous layer. Therefore, a porous electrode foil having a higher porosity can be obtained as the number of different phase components increases.
異相成分としては、タンタルに実質的に溶解しない金属成分、または、タンタルに対して熱力学的に安定な酸化物などから選択する。金属成分としては、マグネシウム、カルシウムのようなアルカリ土類金属のほか、銅、銀などの金属を用いることができる。ただし、後述する電解工程において、電解による異相成分の除去を行うには実質上銅または銀であることが好ましく、さらには経済性から銅を用いることが好ましい。 The heterogeneous component is selected from a metal component that does not substantially dissolve in tantalum, an oxide that is thermodynamically stable against tantalum, and the like. As the metal component, metals such as copper and silver can be used in addition to alkaline earth metals such as magnesium and calcium. However, in the electrolysis process to be described later, in order to remove the heterogeneous component by electrolysis, it is preferably substantially copper or silver, and more preferably copper from the viewpoint of economy.
（２）真空熱処理することによりタンタルと異相成分とをそれぞれ粒成長させる工程
前記工程で得られた混合膜を真空中で熱処理することにより、タンタルと異相成分を粒成長させる。粒成長させることにより、タンタルと異相成分のそれぞれが構造的につながり、異相成分の完全な選択的除去、および、多孔質層の安定的な構造を得ることが可能となる。
(2) Step of growing grains of tantalum and different phase components by vacuum heat treatment Grains of tantalum and different phase components are grown by heat-treating the mixed film obtained in the step in vacuum. By grain growth, each of the tantalum and the heterogeneous phase component is structurally connected, and it becomes possible to obtain a complete selective removal of the heterogeneous phase component and a stable structure of the porous layer.
（３）溶接工程
電解による異相成分の除去を行うために、熱処理された混合膜にリード線を溶接する。
(3) Welding process In order to remove heterogeneous components by electrolysis, a lead wire is welded to the heat-treated mixed film.
（４）電解工程
本発明では、異相成分が酸化皮膜中に取り込まれる可能性のために採用され難いと考えられていた、異相成分の除去と多孔質バルブ層の陽極酸化を一つの連続した、あるいは同時的な電解によって行う点に特徴がある。
(4) Electrolysis step In the present invention, the removal of the different phase component and the anodic oxidation of the porous valve layer, which were thought to be difficult to adopt because of the possibility that the different phase component is incorporated into the oxide film, Alternatively, it is characterized in that it is performed by simultaneous electrolysis.
本発明の主眼は、多孔質バルブ陽極体の製造におけるコスト削減にあることから、電解液の種類は、異相成分除去用の電解液と陽極酸化用の電解液を同一にすることが好ましい。陽極酸化で使用できる電解液であるリン酸水溶液、シュウ酸水溶液、硫酸水溶液は、異相成分の除去でも使用できることから、電解工程の電解液としては、これらのうちいずれか一つを採用することが好ましい。 Since the main point of the present invention is cost reduction in the production of the porous valve anode body, it is preferable that the electrolytic solution is the same as the electrolytic solution for removing the heterogeneous component and the electrolytic solution for anodic oxidation. Since an aqueous solution of phosphoric acid, an aqueous solution of oxalic acid, and an aqueous solution of sulfuric acid, which can be used in anodization, can also be used for removing heterogeneous components, any one of them can be used as an electrolytic solution in the electrolysis process. preferable.
電解液の温度に関して、異相成分の除去の観点からは、異相成分である銅（Ｃｕ）の溶解速度を大きくすることで、溶解時間の短縮化が図られるため、室温より高い４０℃以上とすることが好ましい。一方、９５℃を超えると、電解液の流動状態が激しくなり、異相成分の除去により生成される多孔質バルブ層を損傷させるおそれがあることから、９５℃以下とすることが好ましい。 Regarding the temperature of the electrolytic solution, from the viewpoint of removing the heterogeneous component, the melting time can be shortened by increasing the dissolution rate of copper (Cu), which is the heterophasic component. It is preferable. On the other hand, when the temperature exceeds 95 ° C., the flow state of the electrolytic solution becomes violent, and the porous valve layer generated by removing the heterogeneous component may be damaged.
陽極酸化の観点からも、陽極酸化時間の短縮のために、室温より高い４０℃以上とすることが好ましい。一方、９５℃を超えると、電解液の流動状態が激しくなり、陽極酸化皮膜を損傷させるおそれがあることから、９５℃以下とすることが好ましい。 From the viewpoint of anodic oxidation, it is preferable that the temperature be 40 ° C. or higher, which is higher than room temperature, in order to shorten the anodic oxidation time. On the other hand, if it exceeds 95 ° C., the flow state of the electrolytic solution becomes violent, and the anodized film may be damaged.
以上のように、連続する、または同時的に行われる電解工程を通じて、電解液の温度を、４０℃以上９５℃以下に規制することが好ましいといえる。さらに好ましくは、６０℃以上９０℃以下の範囲とする。 As described above, it can be said that it is preferable to regulate the temperature of the electrolytic solution to 40 ° C. or more and 95 ° C. or less through continuous or simultaneous electrolysis processes. More preferably, it is set as the range of 60 degreeC or more and 90 degrees C or less.
上記の電解液の種類と電解液温度の範囲において、電解液の電気伝導度に関して、異相成分除去の観点からは、電気伝導度が３ｍＳ／ｃｍ未満の場合には、異相成分である銅（Ｃｕ）の溶解速度が小さくなるため、実際的ではない。一方、５０ｍＳ／ｃｍを超えると、銅の溶解が急激に進み、得られる多孔質バルブ層を損傷させる可能性があるので好ましくない。また、陽極酸化の観点からも、電気伝導度が３ｍＳ／ｃｍ未満の場合には、均一な陽極酸化皮膜が形成されないおそれがあり、漏れ電流の増加を招く可能性がある。一方、電気伝導度が高ければ陽極酸化の効率は上がるものの。５０ｍＳ／ｃｍ程度で十分な効率が達成されるため、電気伝導度を５０ｍＳ／ｃｍ以下とすることが好ましい。 From the viewpoint of removing the heterogeneous component, regarding the electrical conductivity of the electrolytic solution in the range of the type of the electrolytic solution and the electrolytic solution temperature, when the electrical conductivity is less than 3 mS / cm, copper (Cu ) Is not practical because the dissolution rate is small. On the other hand, if it exceeds 50 mS / cm, dissolution of copper proceeds rapidly, and the resulting porous valve layer may be damaged. From the viewpoint of anodic oxidation, if the electrical conductivity is less than 3 mS / cm, there is a possibility that a uniform anodic oxide film may not be formed, which may increase leakage current. On the other hand, if the electrical conductivity is high, the efficiency of anodic oxidation increases. Since sufficient efficiency is achieved at about 50 mS / cm, the electrical conductivity is preferably 50 mS / cm or less.
以上のように、連続する、または同時的に行われる電解工程を通じて、上記の電解液の種類と電解液温度の範囲において、電解液の電気伝導度を３ｍＳ／ｃｍ以上５０ｍＳ／ｃｍ以下に規制することが好ましいといえる。さらに好ましくは、５ｍＳ／ｃｍ以上２０ｍＳ／ｃｍ以下の範囲とする。 As described above, the electric conductivity of the electrolytic solution is regulated to 3 mS / cm or more and 50 mS / cm or less in the range of the kind of the electrolytic solution and the temperature of the electrolytic solution through continuous or simultaneous electrolytic processes. It can be said that it is preferable. More preferably, it is in the range of 5 mS / cm or more and 20 mS / cm or less.
電解の制御方法としては、一般に用いられる定電流電解と定電圧電解を用いることができる。 As a method for controlling electrolysis, generally used constant current electrolysis and constant voltage electrolysis can be used.
異相成分の除去を定電圧電解で行う場合、０．１Ｖ以上１０Ｖ以下の範囲から選ばれる電圧で定電圧電解を行うことが好ましい。０．１Ｖ未満の場合には、異相成分である銅（Ｃｕ）の溶解速度が小さくなって、その除去に多くの時間を要するため適切ではない。一方、１０Ｖを超えると、銅の溶解と同時に実質的な陽極酸化が始まる。したがって、異相成分の除去を優先的に行わせる場合には、電圧を１０Ｖ以下とすることが好ましい。さらに好ましくは、０．５Ｖ以上２Ｖ以下の範囲から電圧を選択する。 When removing the heterogeneous component by constant voltage electrolysis, it is preferable to perform constant voltage electrolysis at a voltage selected from a range of 0.1 V or more and 10 V or less. If it is less than 0.1 V, the dissolution rate of copper (Cu), which is a heterogeneous component, becomes small, and it takes a lot of time to remove it, which is not appropriate. On the other hand, when the voltage exceeds 10 V, substantial anodization starts simultaneously with the dissolution of copper. Therefore, when removing the heterogeneous component preferentially, the voltage is preferably set to 10 V or less. More preferably, the voltage is selected from the range of 0.5 V or more and 2 V or less.
異相成分の除去を定電流電解で行う場合、０．００１ｍＡ／μＦＶ以上０．１ｍＡ／μＦＶ以下の範囲から選ばれる電流密度で定電流電解を行うことが好ましい。０．００１ｍＡ／μＦＶ未満の場合には、異相成分である銅（Ｃｕ）の溶解速度が小さくなって、その除去に多くの時間を要するため適切ではない。一方、０．１ｍＡ／μＦＶを超える場合には、電圧上昇を招き、銅の溶解と同時に実質的な陽極酸化が始まる。したがって、異相成分の除去を優先的に行わせる場合には、０．１ｍＡ／μＦＶ以下とすることが好ましい。さらに好ましくは、０．００５ｍＡ／μＦＶ以上０．０５ｍＡ／μＦＶ以下の範囲から電流密度を選択する。 When removing the heterogeneous component by constant current electrolysis, it is preferable to perform constant current electrolysis at a current density selected from the range of 0.001 mA / μFV to 0.1 mA / μFV. If it is less than 0.001 mA / μFV, the dissolution rate of copper (Cu), which is a heterogeneous component, becomes small, and it takes a lot of time to remove it, which is not appropriate. On the other hand, when it exceeds 0.1 mA / μFV, the voltage rises and substantial anodic oxidation starts simultaneously with the dissolution of copper. Therefore, in the case where the removal of the heterogeneous component is performed preferentially, it is preferably 0.1 mA / μFV or less. More preferably, the current density is selected from the range of 0.005 mA / μFV to 0.05 mA / μFV.
陽極酸化のための電解については、陽極酸化皮膜の厚みが電圧に比例するため、定電圧電解とすることが好ましく、電圧を３Ｖ以上１００Ｖ以下の範囲から電圧を選択的に設定することが好ましい。陽極酸化において、酸化皮膜（誘電体）の厚さは印可する電圧に比例する（以下、このときの比例定数を「化成定数」と記す）。したがって、酸化皮膜（誘電体）の厚さは、化成定数と陽極酸化電圧の積で表すことができる。 The electrolysis for anodization is preferably constant voltage electrolysis because the thickness of the anodized film is proportional to the voltage, and the voltage is preferably set selectively from the range of 3V to 100V. In the anodic oxidation, the thickness of the oxide film (dielectric) is proportional to the applied voltage (hereinafter, the proportionality constant at this time is referred to as “chemical formation constant”). Therefore, the thickness of the oxide film (dielectric) can be expressed by the product of the formation constant and the anodic oxidation voltage.
タンタル（Ｔａ）の場合、化成定数は１．７ｎｍ／Ｖである。 In the case of tantalum (Ta), the formation constant is 1.7 nm / V.
陽極酸化皮膜が生成される多孔質の粒径は、一般的に２０ｎｍ〜３０ｎｍから最大３００ｎｍ程度である。これらの粒径における酸化皮膜の厚みとしては、１０ｎｍ以上で最大値としては１５０ｎｍ程度が想定される。 The porous particle size from which the anodized film is formed is generally about 20 nm to 30 nm to a maximum of about 300 nm. The thickness of the oxide film at these particle sizes is assumed to be 10 nm or more and the maximum value is about 150 nm.
したがって、この陽極酸化皮膜に対応する電圧としては、３Ｖ以上１００Ｖ以下とすることが好ましい。 Therefore, the voltage corresponding to this anodic oxide film is preferably 3 V or more and 100 V or less.
また、３Ｖ未満の場合には、皮膜が薄すぎて不均一となり、漏れ電流を増加させる原因となるため好ましくない。１００Ｖを超える場合には、皮膜が厚すぎるため割れが発生する可能性があり、漏れ電流を増加させる原因となるため好ましくない。 On the other hand, when the voltage is less than 3 V, the film is too thin and non-uniform, which causes an increase in leakage current, which is not preferable. When the voltage exceeds 100 V, the film is too thick, so that cracking may occur, which causes an increase in leakage current, which is not preferable.
実際の電解における制御条件としては、次の３パターンがある。 As control conditions in actual electrolysis, there are the following three patterns.
電解パターンＡ：
ステップ１として、最初に異相成分の除去を目的とした電解を定電圧電解で行い、次にステップ２として、陽極酸化を目的とした電解を定電圧電解で連続的に行うパターンである。
Electrolytic pattern A:
Step 1 is a pattern in which electrolysis for the purpose of removing heterogeneous components is first performed by constant voltage electrolysis, and then step 2 is performed by electrolysis for the purpose of anodic oxidation continuously by constant voltage electrolysis.
ステップ１の電解は、０．１Ｖ以上１０Ｖ以下の範囲から選ばれる電圧で定電圧電解を所定時間行い、ステップ２の電解は、３Ｖ以上１００Ｖ以下の中から選ばれる電圧で定電圧電解を所定時間行う。 In the electrolysis in step 1, constant voltage electrolysis is performed for a predetermined time at a voltage selected from a range of 0.1V to 10V, and in step 2, the constant voltage electrolysis is performed for a predetermined time at a voltage selected from 3V to 100V. Do.
ステップ１において、電解開始から所定電圧に到達するまでの期間、およびステップ２において所定電圧に到達するまでの期間においては、０．００１ｍＡ／μＦＶ以上０．１ｍＡ／μＦＶ以下の範囲から選ばれる電流密度で定電流を供給する。 In step 1, the current density selected from the range of 0.001 mA / μFV to 0.1 mA / μFV in the period from the start of electrolysis until reaching the predetermined voltage and in the period until reaching the predetermined voltage in step 2. Supply a constant current at.
電解パターンＢ：
ステップ１として、最初に異相成分の除去を目的とした電解を定電流電解で行い、次にステップ２として、陽極酸化を目的とした電解を定電圧電解で連続的に行うパターンである。
Electrolytic pattern B:
Step 1 is a pattern in which electrolysis for the purpose of removing heterogeneous components is first carried out by constant current electrolysis, and then in step 2 electrolysis for the purpose of anodic oxidation is continuously carried out by constant voltage electrolysis.
ステップ１の電解は、０．００１ｍＡ／μＦＶ以上０．１ｍＡ／μＦＶ以下の範囲から選ばれる電流密度で定電流電解を所定時間行い、ステップ２の電解は、３Ｖ以上１００Ｖ以下の範囲から選ばれる電圧で定電圧電解を所定時間行う。 The electrolysis in step 1 is carried out for a predetermined time at a current density selected from the range of 0.001 mA / μFV to 0.1 mA / μFV, and the electrolysis in step 2 is a voltage selected from the range of 3 V to 100 V. Then, constant voltage electrolysis is performed for a predetermined time.
ステップ２において、所定電圧に到達するまでの期間は、ステップ１の電解で設定した電流密度で定電流を供給する。 In step 2, a constant current is supplied at a current density set by electrolysis in step 1 until a predetermined voltage is reached.
電解パターンＣ：
異相成分の除去を目的とした電解と陽極酸化を目的とした電解を定電圧電解で同時に行うパターンである。
Electrolytic pattern C:
In this pattern, electrolysis for the purpose of removing heterogeneous components and electrolysis for the purpose of anodic oxidation are performed simultaneously by constant voltage electrolysis.
この場合についても、３Ｖ以上１００Ｖ以下の範囲から選ばれる電圧で定電圧電解を所定時間行う。電解開始から所定電圧に到達するまでの電解は０．００１ｍＡ／μＦＶ以上０．１ｍＡ／μＦＶ以下の範囲から選ばれる電流密度で定電流を供給する。 Also in this case, constant voltage electrolysis is performed for a predetermined time at a voltage selected from the range of 3V to 100V. Electrolysis from the start of electrolysis until reaching a predetermined voltage supplies a constant current at a current density selected from the range of 0.001 mA / μFV to 0.1 mA / μFV.
このように、電解パターンＡのステップ１において電解開始から所定電圧に到達するまでの期間、ステップ２において所定電圧に到達するまでの期間、電解パターンＢにおける所定電圧に到達するまでの期間、および電解パターンＣにおける電解開始から所定電圧に到達するまでの期間において、０．００１ｍＡ／μＦＶ以上０．１ｍＡ／μＦＶ以下の範囲から選ばれる電流密度で定電流を供給する。これは、０．００１ｍＡ／μＦＶ未満の場合には、所定の電圧に到達するまでの期間が長く必要となり、実際的ではなく、０．１ｍＡ／μＦＶを超える場合には、所定の電圧に到達する期間は短くなるものの、全体の電解時間を考慮すると、その効果は小さいためエネルギー効率の観点より得策ではないためである。 As described above, in Step 1 of the electrolytic pattern A, the period from the start of electrolysis until reaching the predetermined voltage, the period until reaching the predetermined voltage in Step 2, the period until reaching the predetermined voltage in the electrolytic pattern B, and the electrolysis In the period from the start of electrolysis in pattern C until reaching a predetermined voltage, a constant current is supplied at a current density selected from the range of 0.001 mA / μFV to 0.1 mA / μFV. This is because if it is less than 0.001 mA / μFV, it takes a long time to reach the predetermined voltage, which is not practical, and if it exceeds 0.1 mA / μFV, it reaches the predetermined voltage. This is because, although the period is shortened, considering the entire electrolysis time, the effect is small and it is not a good measure from the viewpoint of energy efficiency.
本発明者の知見によれば、これらのパターンにおいて、得られる箔状の多孔質バルブ金属陽極体の特性には変化はなく、いずれのパターンも効率やコストの観点から適宜選択しうる。ただし、最終製品となる電解コンデンサに要求される性能とパターンが相関する場合には、より適切なパターンを適宜選択しうる。 According to the knowledge of the present inventors, in these patterns, the characteristics of the obtained foil-like porous valve metal anode body are not changed, and any pattern can be appropriately selected from the viewpoints of efficiency and cost. However, if the performance required for the electrolytic capacitor as the final product correlates with the pattern, a more appropriate pattern can be appropriately selected.
［実施例１］
スパッタリングターゲットとして、純度９９．９９％のタンタル（Ｔａ）ターゲットおよび銅（Ｃｕ）ターゲット（いずれもφ１５２．４ｍｍ、株式会社高純度化学研究所製）と、基材として、５０ｍｍ×５０ｍｍ、厚み５０μｍのＴａ箔(東京電解株式会社製)とを、多元スパッタリング装置（株式会社アルバック製、ＳＢＨ−２２０６ＲＤＥ）に設置し、１．０Ｐａのアルゴン（Ａｒ）雰囲気中、Ｔａ−６０ｖｏｌ％Ｃｕの混合膜となるように電力比を調整し、ＴａターゲットおよびＣｕターゲットを同時にスパッタリングし、基材上にＴａ−６０ｖｏｌ％Ｃｕからなる厚み１０μｍの混合膜を基材の両面に形成した。得られた成膜材料を、高温真空炉（株式会社東京真空製、ｔｕｒｂｏ−ｖａｃ）中で、真空度５×１０-3Ｐａ以下の真空雰囲気で加熱を開始し、７００℃×６０ｍｉｎの条件で熱処理を行った。
[Example 1]
As a sputtering target, a tantalum (Ta) target having a purity of 99.99% and a copper (Cu) target (both are φ152.4 mm, manufactured by Kojundo Chemical Laboratory Co., Ltd.), and a substrate is 50 mm × 50 mm and 50 μm in thickness. Ta foil (manufactured by Tokyo Electrolytic Co., Ltd.) is installed in a multi-source sputtering apparatus (manufactured by ULVAC, Inc., SBH-2206RDE) and becomes a mixed film of Ta-60 vol% Cu in an argon (Ar) atmosphere of 1.0 Pa. The power ratio was adjusted as described above, and the Ta target and the Cu target were simultaneously sputtered to form a 10 μm thick mixed film of Ta-60 vol% Cu on both surfaces of the substrate. The obtained film-forming material was heated in a high-temperature vacuum furnace (Tokyo Vacuum Co., Ltd., turbo-vac) in a vacuum atmosphere with a degree of vacuum of 5 × 10 −3 Pa or less, under the conditions of 700 ° C. × 60 min. Heat treatment was performed.
熱処理後の成膜材料を１０ｍｍ角に切断し、この切断片に直径０．２ｍｍのニオブ（Ｎｂ）ワイヤー（東京電解株式会社製)を抵抗溶接した。 The film-forming material after the heat treatment was cut into 10 mm square, and a 0.2 mm diameter niobium (Nb) wire (manufactured by Tokyo Electrolytic Co., Ltd.) was resistance welded to the cut piece.
続いて、電気伝導度１０ｍＳ／ｃｍ、８０℃のリン酸水溶液中で、電解パターンＡの電解を行った。 Subsequently, the electrolytic pattern A was electrolyzed in a phosphoric acid aqueous solution having an electric conductivity of 10 mS / cm and 80 ° C.
ステップ１の電解では、電圧０．５Ｖ、時間３ｈの定電圧電解を行って、異相成分であるＣｕをリン酸水溶液中に選択的に溶解除去させることで、バルブ金属多孔質層を形成した。このステップ１において電圧が０．５Ｖに到達するまでの電解初期においては、電流密度が０．０１ｍＡ／μＦＶとなるように１０ｍｍ角の成膜材料１個あたり２５ｍＡの定電流を供給した。 In the electrolysis of Step 1, a valve metal porous layer was formed by performing constant voltage electrolysis at a voltage of 0.5 V for 3 hours to selectively dissolve and remove Cu, which is a heterogeneous component, in a phosphoric acid aqueous solution. In the initial stage of electrolysis until the voltage reached 0.5 V in Step 1, a constant current of 25 mA was supplied per 10 mm square film forming material so that the current density was 0.01 mA / μFV.
ステップ２の電解では、電圧１０Ｖに到達するまでの期間においては、電流密度が０．０１ｍＡ／μＦＶとなるように定電流を供給し、電圧１０Ｖに到達後、時間６ｈの定電圧電解を行って、バルブ金属多孔質層の表面に酸化皮膜を形成した。 In the electrolysis in step 2, constant current is supplied so that the current density becomes 0.01 mA / μFV until the voltage reaches 10V, and constant voltage electrolysis is performed for 6 hours after reaching the voltage of 10V. An oxide film was formed on the surface of the valve metal porous layer.
このようにして得られた多孔質バルブ金属陽極体を、イオン交換水で洗浄した後、４０℃で１２時間乾燥したのち３０ｖｏｌ％の硫酸水溶液中に浸漬し、白金黒付き白金箔電極を対極として、ＬＣＲメータ（アジレント・テクノロジー株式会社製、４２６３Ｂ）を用い、１２０Ｈｚ、ＤＣ１．５Ｖ、１．０Ｖｒｍｓの条件で、静電容量を測定した。また、超高抵抗／微小電流計（株式会社アドバンテスト製、Ｒ８３４０）を用い、７Ｖを印加して、５ｍｉｎ後の漏れ電流を測定した。測定した漏れ電流（ｎＡ）を、静電容量（μＦ）と測定時の印加電圧（Ｖｍ）で割り、ＬＣ（ｎＡ／μＦＶｍ）を算出して得た。 The porous valve metal anode body thus obtained was washed with ion-exchanged water, dried at 40 ° C. for 12 hours, and then immersed in a 30 vol% sulfuric acid aqueous solution, using a platinum black electrode with platinum black as a counter electrode. The electrostatic capacity was measured under the conditions of 120 Hz, DC 1.5 V, and 1.0 Vrms using an LCR meter (manufactured by Agilent Technologies, 4263B). Further, using an ultrahigh resistance / microammeter (manufactured by Advantest Co., Ltd., R8340), 7 V was applied and the leakage current after 5 minutes was measured. The measured leakage current (nA) was divided by the capacitance (μF) and the applied voltage (Vm) at the time of measurement to obtain LC (nA / μFVm).
その製造条件および測定結果を表１に示す。 The production conditions and measurement results are shown in Table 1.
［実施例２］
熱処理工程において、１０００℃×６０ｍｉｎの条件で熱処理を行ったこと、ステップ１の電解工程において、電圧５Ｖ、時間０．５ｈの定電圧電解を行ったこと（なお、電圧が５Ｖに到達するまでの電解初期は、電流密度が０．０１ｍＡ／μＦＶとなるように、１０ｍｍ角の成膜材料１個あたり１０ｍＡの定電流を供給した）、ステップ２の電解工程において、電圧７０Ｖに到達するまでの期間において、電流密度が０．０１ｍＡ／μＦＶで定電流を供給し、電圧７０Ｖに到達後、時間６ｈの定電圧電解を行ったこと以外は、実施例１と同様にして多孔質バルブ金属陽極体を得て、その静電容量および漏れ電流を測定した。
[Example 2]
In the heat treatment process, heat treatment was performed under conditions of 1000 ° C. × 60 min, and in the electrolysis process in Step 1, constant voltage electrolysis was performed at a voltage of 5 V for a time of 0.5 h (in addition, until the voltage reached 5 V) In the initial stage of electrolysis, a constant current of 10 mA was supplied for each 10 mm square film forming material so that the current density was 0.01 mA / μFV), and the period until the voltage reached 70 V in the electrolysis process of Step 2 In Example 1, a porous valve metal anode body was prepared in the same manner as in Example 1, except that a constant current was supplied at a current density of 0.01 mA / μFV and constant voltage electrolysis was performed for 6 hours after reaching a voltage of 70 V. The capacitance and leakage current were measured.
その製造条件および測定結果を表１に示す。 The production conditions and measurement results are shown in Table 1.
［実施例３］
電解工程においてパターンＢの電解を行ったこと以外は、実施例１と同様にして多孔質バルブ金属陽極体を得た。
[Example 3]
A porous valve metal anode body was obtained in the same manner as in Example 1 except that pattern B was electrolyzed in the electrolysis process.
具体的には、ステップ１の電解では、電流密度が０．０１ｍＡ／μＦＶ、時間０．５ｈの定電流電解を行って、Ｃｕをリン酸水溶液中に選択的に溶解除去させることでバルブ金属多孔質層を形成した。この電流密度を得るためには、１０ｍｍ角の成膜材料１個あたり２５ｍＡの電流を供給した。 Specifically, in the electrolysis in Step 1, constant current electrolysis is performed at a current density of 0.01 mA / μFV for a time of 0.5 h, and Cu is selectively dissolved and removed in an aqueous phosphoric acid solution to remove porous metal from the valve. A quality layer was formed. In order to obtain this current density, a current of 25 mA was supplied per 10 mm square film forming material.
ステップ２の電解では、実施例１と同様に、電圧１０Ｖに到達するまでの期間においては、電流密度が０．０１ｍＡ／μＦＶで定電流を供給し、電圧１０Ｖに到達後、時間６ｈの定電圧電解を行って、バルブ金属多孔質層の表面に酸化皮膜を形成した。 In the electrolysis of Step 2, as in Example 1, in the period until the voltage reaches 10V, a constant current is supplied at a current density of 0.01 mA / μFV, and after reaching the voltage of 10V, the constant voltage for 6 hours. Electrolysis was performed to form an oxide film on the surface of the valve metal porous layer.
得られた多孔質バルブ金属陽極体について、実施例１と同様に静電容量および漏れ電流を測定した。その製造条件および測定結果を表１に示す。 With respect to the obtained porous valve metal anode body, the capacitance and leakage current were measured in the same manner as in Example 1. The production conditions and measurement results are shown in Table 1.
［実施例４］
ステップ１の電解において、電流密度が０．００２ｍＡ／μＦＶ、時間１ｈの定電流電解を行った（この電流密度を得るためには１０ｍｍ角の成膜材料１個あたり５ｍＡの電流を供給した）こと以外は、実施例３と同様にして、多孔質バルブ金属陽極体を得て、その静電容量および漏れ電流を測定した。
[Example 4]
In the electrolysis of Step 1, constant current electrolysis was performed at a current density of 0.002 mA / μFV for 1 hour (to obtain this current density, a current of 5 mA was supplied per 10 mm square film forming material). Except for the above, a porous valve metal anode body was obtained in the same manner as in Example 3, and the capacitance and leakage current were measured.
その製造条件および測定結果を表１に示す。 The production conditions and measurement results are shown in Table 1.
［実施例５］
ステップ１の電解において、電流密度が０．１ｍＡ／μＦＶ、時間０．１ｈの定電流電解を行った（この電流密度を得るためには１０ｍｍ角の成膜材料１個あたり２５０ｍＡの電流を供給した）こと以外は、実施例３と同様にして、多孔質バルブ金属陽極体を得て、その静電容量および漏れ電流を測定した。
[Example 5]
In the electrolysis of Step 1, constant current electrolysis was performed with a current density of 0.1 mA / μFV and a time of 0.1 h (in order to obtain this current density, a current of 250 mA was supplied per 10 mm square film forming material. Except for the above, a porous valve metal anode body was obtained in the same manner as in Example 3, and its capacitance and leakage current were measured.
その製造条件および測定結果を表１に示す。 The production conditions and measurement results are shown in Table 1.
［実施例６］
電解工程においてパターンＣの電解を行ったこと以外は、実施例１と同様にして多孔質バルブ金属陽極体を得た。
[Example 6]
A porous valve metal anode body was obtained in the same manner as in Example 1 except that pattern C was electrolyzed in the electrolysis process.
具体的には、電流密度が０．１ｍＡ／μＦＶになるように１０ｍｍ角の成膜材料1個あたり２５０ｍＡの定電流を供給し、電圧１０Ｖに到達後、時間６ｈの定電圧電解を行って、バルブ金属多孔質層の形成と酸化皮膜の形成とを同時に行った。 Specifically, a constant current of 250 mA is supplied per 10 mm square film forming material so that the current density becomes 0.1 mA / μFV, and after reaching a voltage of 10 V, constant voltage electrolysis is performed for 6 hours, The formation of the valve metal porous layer and the formation of the oxide film were performed simultaneously.
得られた多孔質バルブ金属陽極体について、実施例１と同様に静電容量および漏れ電流を測定した。その製造条件および測定結果を表１に示す。 With respect to the obtained porous valve metal anode body, the capacitance and leakage current were measured in the same manner as in Example 1. The production conditions and measurement results are shown in Table 1.
［実施例７］
基材として５０ｍｍ×５０ｍｍ、厚み５０μｍのＮｂ箔を用い、かかるＮｂ箔の上にＮｂ−６０ｖｏｌ％Ｃｕからなる厚み１０μｍの混合膜を基材の両面に形成し、高温真空炉中で、真空度５×１０-3Ｐａ以下の真空雰囲気で加熱を開始して８５０℃×６０ｍｉｎの条件で熱処理を行ったこと、ステップ２における化成電圧を５．０Ｖとしたこと以外は、実施例１と同様に電解パターンＡの電解を行い、多孔質バルブ金属陽極体を得て、その静電容量および漏れ電流を測定した。
[Example 7]
Using a Nb foil of 50 mm × 50 mm and a thickness of 50 μm as a base material, a mixed film of 10 μm thickness made of Nb-60 vol% Cu is formed on both sides of the Nb foil, and the degree of vacuum in a high-temperature vacuum furnace The same as in Example 1 except that heating was started in a vacuum atmosphere of 5 × 10 −3 Pa or less and heat treatment was performed under the conditions of 850 ° C. × 60 min, and the formation voltage in Step 2 was 5.0 V. Electrolysis of the electrolytic pattern A was performed to obtain a porous valve metal anode body, and the capacitance and leakage current were measured.
その製造条件および測定結果を表１に示す。 The production conditions and measurement results are shown in Table 1.
［実施例８］
電解工程においてパターンＢの電解を行ったこと以外は、実施例７と同様にして多孔質バルブ金属陽極体を得た。
[Example 8]
A porous valve metal anode body was obtained in the same manner as in Example 7 except that pattern B was electrolyzed in the electrolysis process.
具体的には、実施例３と同様に、ステップ１の電解では、電流密度が０．０１ｍＡ／μＦＶ、時間０．５ｈの定電流電解を行い（この電流密度を得るためには、１０ｍｍ角の成膜材料１個あたり２５ｍＡの電流を供給した）、ステップ２の電解では、電圧１０Ｖに到達するまでの期間においては、電流密度が０．０１ｍＡ／μＦＶで定電流を供給し、電圧１０Ｖに到達後、時間６ｈの定電圧電解を行った。 Specifically, as in Example 3, in the electrolysis of Step 1, constant current electrolysis was performed at a current density of 0.01 mA / μFV and a time of 0.5 h (in order to obtain this current density, a 10 mm square) In the electrolysis of step 2, a constant current was supplied at a current density of 0.01 mA / μFV and reached a voltage of 10 V in the period until the voltage of 10 V was reached. Thereafter, constant voltage electrolysis was performed for 6 hours.
得られた多孔質バルブ金属陽極体について、実施例１と同様に静電容量および漏れ電流を測定した。その製造条件および測定結果を表１に示す。 With respect to the obtained porous valve metal anode body, the capacitance and leakage current were measured in the same manner as in Example 1. The production conditions and measurement results are shown in Table 1.
[従来例１]
実施例１と同様にして得た成膜材料について、実施例１と同様の熱処理を行った後、得られた熱処理後の成膜材料を２．３ｍｏｌ／Ｌ（リットル）の硝酸水溶液に浸漬し、Ｃｕを選択的に溶解除去した。その後、純水洗浄、乾燥を行なって、両面にＴａ多孔質層が形成された陽極体を作製した。
[Conventional example 1]
The film-forming material obtained in the same manner as in Example 1 was subjected to the same heat treatment as in Example 1, and the obtained film-formed material after the heat treatment was immersed in a 2.3 mol / L (liter) nitric acid aqueous solution. Cu was selectively dissolved and removed. Thereafter, washing with pure water and drying were performed to prepare an anode body in which a Ta porous layer was formed on both surfaces.
陽極体を１０ｍｍ角に切断し、スポットウエルダで直径０．２ｍｍのＮｂワイヤーをリードとして取り付けた後、陽極酸化処理を行って、誘電体皮膜を形成した。すなわち、電気伝導度１０ｍＳ／ｃｍ、８０℃のリン酸水溶液中で、電圧１０Ｖに到達するまでの期間においては、電流密度が０．０１ｍＡ／μＦＶで定電流を供給し、電圧１０Ｖに到達後、時間３ｈの定電圧電解を行って、多孔質層の表面に酸化皮膜を形成した（電解パターンＤ）。 The anode body was cut into 10 mm square, and an Nb wire having a diameter of 0.2 mm was attached as a lead with a spot welder, and then anodization was performed to form a dielectric film. That is, a constant current is supplied at a current density of 0.01 mA / μFV in a phosphoric acid aqueous solution with an electrical conductivity of 10 mS / cm and 80 ° C. until the voltage reaches 10 V, and after reaching a voltage of 10 V, Constant voltage electrolysis was performed for 3 hours to form an oxide film on the surface of the porous layer (electrolytic pattern D).
これをイオン交換水で洗浄した後、４０℃で１２時間乾燥して多孔質バルブ金属陽極体を得た。以下、実施例１と同様に、静電容量と漏れ電流を測定した。その製造条件および測定結果を表２に示す。 This was washed with ion-exchanged water and then dried at 40 ° C. for 12 hours to obtain a porous valve metal anode body. Thereafter, the capacitance and leakage current were measured in the same manner as in Example 1. The production conditions and measurement results are shown in Table 2.
［従来例２］
電解パターンＤにおいて、時間６ｈの定電圧電解を行ったこと以外は、従来例１と同様にして、多孔質バルブ金属陽極体を得て、静電容量と漏れ電流を測定した。その製造条件および測定結果を表２に示す。
[Conventional example 2]
In the electrolytic pattern D, a porous valve metal anode body was obtained in the same manner as in Conventional Example 1 except that constant voltage electrolysis was performed for 6 hours, and the capacitance and leakage current were measured. The production conditions and measurement results are shown in Table 2.
［従来例３］
実施例７と同様にして得た成膜材料について、実施例７と同様の熱処理を行った後、得られた熱処理後の成膜材料を２．３ｍｏｌ／Ｌの硝酸に浸漬し、Ｃｕを選択的に溶解除去した。その後、純水洗浄、乾燥を行なって、両面にＮｂ多孔質層が形成された陽極体を作製した。
[Conventional Example 3]
For the film forming material obtained in the same manner as in Example 7, the same heat treatment as in Example 7 was performed, and then the obtained film forming material after the heat treatment was immersed in 2.3 mol / L nitric acid, and Cu was selected. Dissolved and removed. Thereafter, pure water washing and drying were performed to prepare an anode body in which an Nb porous layer was formed on both surfaces.
陽極体を１０ｍｍ角に切断し、スポットウエルダで直径０．２ｍｍのＮｂワイヤーをリードとして取り付けた後、陽極酸化処理を行って、誘電体皮膜を形成した。すなわち、電解パターンＤにより、電気伝導度１０ｍＳ／ｃｍ、８０℃のリン酸水溶液中で、電圧５．０Ｖに到達するまでの期間においては、電流密度０．０１ｍＡ／μＦＶで定電流を供給し、電圧５．０Ｖに到達後、時間６Ｈの定電圧電解を行って、多孔質層の表面に酸化皮膜を形成した。これをイオン交換水で洗浄した後、４０℃で１２時間乾燥して多孔質バルブ金属陽極体を得た。以下、実施例１と同様に、静電容量と漏れ電流を測定した。その製造条件および測定結果を表２に示す。 The anode body was cut into 10 mm square, and an Nb wire having a diameter of 0.2 mm was attached as a lead with a spot welder, and then anodization was performed to form a dielectric film. That is, according to the electrolytic pattern D, a constant current is supplied at a current density of 0.01 mA / μFV in a phosphoric acid aqueous solution having an electric conductivity of 10 mS / cm and an electric temperature of 80 ° C. until reaching a voltage of 5.0 V. After reaching the voltage of 5.0 V, constant voltage electrolysis was performed for 6 hours to form an oxide film on the surface of the porous layer. This was washed with ion-exchanged water and then dried at 40 ° C. for 12 hours to obtain a porous valve metal anode body. Thereafter, the capacitance and leakage current were measured in the same manner as in Example 1. The production conditions and measurement results are shown in Table 2.
［従来例４］
電解パターンＤにおいて、電圧１０Ｖの定電圧電解を行ったこと以外は、従来例３と同様にして、多孔質バルブ金属陽極体を得て、静電容量と漏れ電流を測定した。その製造条件および測定結果を表２に示す。
In the electrolytic pattern D, a porous valve metal anode body was obtained in the same manner as in Conventional Example 3 except that constant voltage electrolysis was performed at a voltage of 10 V, and the capacitance and leakage current were measured. The production conditions and measurement results are shown in Table 2.
［評価］
実施例の結果から、熱処理された混合膜から異相成分を除去してバルブ金属多孔質層を形成する工程と陽極酸化処理して酸化（誘電体）皮膜を形成する工程を連続的もしくは同時的に一括に行い工程数を減らしても、従来の特性と同じ多孔質バルブ金属陽極体を作製できることが理解される。わかった。
[Evaluation]
From the results of the examples, the steps of removing the heterogeneous components from the heat-treated mixed film to form the valve metal porous layer and the step of forming the oxidation (dielectric) film by anodizing are performed continuously or simultaneously. It is understood that the porous valve metal anode body having the same characteristics as the conventional characteristics can be produced even if the number of steps is reduced in a lump. all right.
このため、排気設備なども必要なく、バルブ金属多孔質層や酸化皮膜を損傷することなく、箔状の多孔質バルブ金属陽極体の製造コストを低減できる。 For this reason, no exhaust equipment is required, and the manufacturing cost of the foil-like porous valve metal anode body can be reduced without damaging the valve metal porous layer and the oxide film.
本発明は、低背化と高容量化が求められている固体電解コンデンサに用いられる陽極体として、性能に優れている多孔質バルブ金属陽極体を、低コストでかつ安定して供給可能とするものである。 The present invention enables low-cost and stable supply of a porous valve metal anode body having excellent performance as an anode body used for a solid electrolytic capacitor that is required to have a low profile and a high capacity. Is.
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| JP2004304167A (en) * | 2003-03-20 | 2004-10-28 | Advanced Lcd Technologies Development Center Co Ltd | Wiring, display device and method for forming the same |
| JP2006049816A (en) * | 2004-07-05 | 2006-02-16 | Sumitomo Metal Mining Co Ltd | Porous bulb metal film |
| JP2007305780A (en) * | 2006-05-11 | 2007-11-22 | Sumitomo Metal Mining Co Ltd | Metallic porous-foil anode body and its manufacturing method |
| JP2008080277A (en) * | 2006-09-28 | 2008-04-10 | Kurita Water Ind Ltd | Method and apparatus for recovering phosphoric acid from phosphoric acid-containing water |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2004304167A (en) * | 2003-03-20 | 2004-10-28 | Advanced Lcd Technologies Development Center Co Ltd | Wiring, display device and method for forming the same |
| JP2006049816A (en) * | 2004-07-05 | 2006-02-16 | Sumitomo Metal Mining Co Ltd | Porous bulb metal film |
| JP2007305780A (en) * | 2006-05-11 | 2007-11-22 | Sumitomo Metal Mining Co Ltd | Metallic porous-foil anode body and its manufacturing method |
| JP2008080277A (en) * | 2006-09-28 | 2008-04-10 | Kurita Water Ind Ltd | Method and apparatus for recovering phosphoric acid from phosphoric acid-containing water |
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