JP4428902B2 - Aluminum alloy clad foil for high pressure anode in electrolytic capacitor - Google Patents
Aluminum alloy clad foil for high pressure anode in electrolytic capacitor Download PDFInfo
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- JP4428902B2 JP4428902B2 JP2001543748A JP2001543748A JP4428902B2 JP 4428902 B2 JP4428902 B2 JP 4428902B2 JP 2001543748 A JP2001543748 A JP 2001543748A JP 2001543748 A JP2001543748 A JP 2001543748A JP 4428902 B2 JP4428902 B2 JP 4428902B2
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- 239000011888 foil Substances 0.000 title claims description 125
- 239000003990 capacitor Substances 0.000 title claims description 31
- 229910000838 Al alloy Inorganic materials 0.000 title claims description 21
- 229910052782 aluminium Inorganic materials 0.000 claims description 49
- 239000012792 core layer Substances 0.000 claims description 48
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 47
- 238000005530 etching Methods 0.000 claims description 39
- 239000010410 layer Substances 0.000 claims description 39
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 claims description 32
- 238000000866 electrolytic etching Methods 0.000 claims description 17
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 16
- 239000007864 aqueous solution Substances 0.000 claims description 12
- 230000000149 penetrating effect Effects 0.000 claims description 12
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 10
- 229910052742 iron Inorganic materials 0.000 claims description 9
- 229910052710 silicon Inorganic materials 0.000 claims description 8
- 229910052745 lead Inorganic materials 0.000 claims description 6
- 239000000243 solution Substances 0.000 claims description 6
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 5
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 229910017604 nitric acid Inorganic materials 0.000 claims description 5
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 229910052719 titanium Inorganic materials 0.000 claims description 4
- 229910052720 vanadium Inorganic materials 0.000 claims description 4
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 239000002344 surface layer Substances 0.000 claims description 2
- 235000010210 aluminium Nutrition 0.000 description 46
- 238000000034 method Methods 0.000 description 25
- 239000000047 product Substances 0.000 description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 14
- 239000000126 substance Substances 0.000 description 14
- 238000006243 chemical reaction Methods 0.000 description 12
- 239000011162 core material Substances 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 238000005452 bending Methods 0.000 description 9
- 238000011282 treatment Methods 0.000 description 6
- 238000005096 rolling process Methods 0.000 description 5
- 238000000137 annealing Methods 0.000 description 4
- 238000005253 cladding Methods 0.000 description 4
- 238000004090 dissolution Methods 0.000 description 4
- 238000005098 hot rolling Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000035515 penetration Effects 0.000 description 4
- 239000002131 composite material Substances 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 239000003929 acidic solution Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005097 cold rolling Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 229910052738 indium Inorganic materials 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- QZPSXPBJTPJTSZ-UHFFFAOYSA-N aqua regia Chemical compound Cl.O[N+]([O-])=O QZPSXPBJTPJTSZ-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- -1 chlorine ions Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 239000002932 luster Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- WYXIGTJNYDDFFH-UHFFFAOYSA-Q triazanium;borate Chemical compound [NH4+].[NH4+].[NH4+].[O-]B([O-])[O-] WYXIGTJNYDDFFH-UHFFFAOYSA-Q 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/04—Electrodes or formation of dielectric layers thereon
- H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure
- H01G9/055—Etched foil electrodes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Laminated Bodies (AREA)
- Pressure Welding/Diffusion-Bonding (AREA)
Description
技術分野
本発明は、電解コンデンサ陽極用アルミニウム合金箔、特に３層からなるアルミニウムクラッド箔に関する。より具体的には、直流電解エッチング後、高い静電容量と高い機械的強度を兼ね備えた電解コンデンサ中高圧陽極用のアルミニウム合金箔に関する。
なお、本発明において「％」及び「ｐｐｍ」とあるのは、それぞれ「重量％」及び「重量ｐｐｍ」を意味する。
背景技術
一般に、電解コンデンサ中高圧用陽極用アルミニウム合金箔は、不純物であるＦｅ及びＳｉの含有を極力抑え、必要に応じて少量のＣｕを添加した純度９９．９８％以上の高純度アルミニウム箔が使用されている。コンデンサとしての静電容量はその表面積に比例することから、アルミニウム合金箔は塩酸等の酸性溶液中で電気化学的にエッチング処理され、拡面化される。エッチングにより拡面化されたアルミニウム箔（エッチド箔）には、その後の陽極酸化により耐電圧をもった酸化アルミニウム皮膜（化成皮膜）が形成される。これを化成工程と言い、化成されたエッチド箔を化成箔という。次いで、この化成箔を、電解液を含浸させたセパレータ紙及び陰極箔とともに巻き込まれてコンデンサ筒（容器）に収容される。
中高圧用陽極用アルミニウム箔は、必要とされる耐電圧が約２００Ｖ以上であり、エッチング後の化成皮膜が厚いため（約２５００Å以上）、化成時にエッチングピットが化成皮膜で塞がらないように、直径約１μｍ程度のトンネル形状を塩素イオンの存在する酸性溶液中での直流電解エッチングにより形成する。このようにして形成されたエッチングピットは、一般にトンネルピットと呼ばれている。
最近は、電子機器の小型化の要求がますます高まり、コンデンサも例外ではない。このため、コンデンサに使用される電極用アルミニウム箔は、単位面積当たりの静電容量、すなわちエッチング後の拡面率が高いことはもとより、エッチド箔を小さく巻き込むためにエッチド箔に高い機械的強度が要求される。
かかる要求の下、エッチング方法の面からも改善が進められている。従来は、中高圧用陽極箔の拡面率を高めるために、塩酸主体の貫通タイプ直流エッチング法が採用されていたが、より高強度のエッチド箔を得るために、塩酸に硫酸を添加した芯残りタイプ直流エッチングの開発がなされ、エッチド箔の強度向上が図られている。
ここに、貫通タイプエッチングとは、トンネルピットを箔面に垂直に断面方向に貫通させて発生させるエッチング方法である。箔の断面のほぼ全面にわたってピットが存在するため、拡面率は高いが、エッチド箔の機械的強度が低い。これに対し、芯残りタイプエッチングとは、トンネルピットを箔面に垂直に発生させることは貫通タイプと同じであるが、ピットの進行を箔の断面方向の途中で止めるエッチング方法である。中央近傍で未エッチング部分が存在するため、貫通タイプに比して機械的強度に優れる。
しかしながら、静電容量の向上と強度の向上とは裏表の関係にあり、静電容量を高めるためにピット数を増加させたり、あるいは芯部の未エッチング部分の厚さを薄くすれば必然的に強度が低下してしまう。強度が低下すれば、小さいコンデンサ筒に収容することが困難になるだけでなく、エッチング工程以後の化成工程、あるいは化成箔の切断工程・巻き取り工程で箔切れが生じ、生産性が著しく低下することとなる。
これまでに電解コンデンサ用アルミニウム箔にクラッド箔を採用した技術も以下のように提案されているものの、いずれも実用化するには未だ改善すべき余地がある。
（１）例えば、特開昭４９−１０３６６号公報には、２枚の９９．９％以上の高純度アルミニウムの間に被覆アルミニウムと略同純度の芯アルミニウム箔が被覆アルミニウム箔と圧延方向が交叉するように介在せられる電解コンデンサ用箔、あるいは２枚の９９．９％以上の高純度被覆アルミニウムの間に被覆アルミニウムよりも若干純度の低いアルミニウム箔が介在せられ、一体化した電解コンデンサ用アルミニウム箔が開示されている。
しかし、この技術では、機械的強度を高めるために、アルミニウム箔全体の厚さに対する芯アルミニウム材の厚さの割合（クラッド比率）を高くせざるを得ず、その下限値に限界がある。すなわち、クラッド比率を高くしなければならない分、それだけ静電容量が犠牲となってしまう。
（２）特開昭５５−７７９８６号公報には、鉄と珪素の含有量がそれぞれ０．０３％以上の比較的低純度のアルミニウム基合金のコアと、このコアの両面にクラッドされた鉄と珪素の含有量がそれぞれ０．２％以下の比較的高純度のアルミニウム基合金からなり、該クラッド層の厚みは片面で該複合体の厚みの２０％以下とする電解コンデンサ用の複合アルミニウム箔が開示されている。
また、特開昭６２−４７１１０号公報には、９９．９８％以上の二層の外層の間に９９．４％未満のアルミニウム合金からなる芯層を介在させるクラッド箔が開示されている。
しかし、これらの技術も、交流エッチングを前提とする低圧用陽極箔として開発されたものであって、そのままでは中高圧用陽極箔として用いることはできない。すなわち、エッチド箔の機械的強度も静電容量も十分改善することができない。
（３）特公平２−５８７６５号公報には、純度９９．９９５％以上のアルミニウム芯層を該芯層の両面に純度９９．０〜９９．９９％のアルミニウム外層でクラッドしてなる立方体方位の結晶に富む電解コンデンサ電極用アルミニウム合金箔が開示されている。
しかし、この技術では、立方体方位占有率の向上、ひいては静電容量を高めることを目的とするにとどまり、機械的強度の向上を望むことはできない。すなわち、静電容量と機械的強度とを同時に改善するためには、さらなる改善の余地が必要である。
（４）特開平４−１２０２３５号公報には、アルミニウム純度が９９．９％以上でかつ立方体方位占有率が８０％以上の２つのアルミニウムの外層間に非立方体方位占有率が４０％以上の箔をクラッドしてなる電解コンデンサ電極用アルミニウム箔が開示されている。
しかし、この技術はトンネルピットの伸長が芯材の立方体方位が低いときに止まることを利用したものにすぎず、静電容量と機械的強度を同時に改善するには至っていない。
（５）特開平４−１２０２３４号公報には、芯材にＺｎ、Ｉｎ、Ｓｎ、Ｐｂのうち１種又は２種以上含むアルミニウム、外層に９９．９％以上のアルミニウムがクラッドされてなる電解コンデンサ電極用アルミニウム箔が開示されている。
しかし、Ｚｎ、Ｉｎ、Ｓｎ、Ｐｂ等はアルミニウム中での拡散速度が速く、中高圧用陽極箔のように５００℃近傍に焼鈍した場合にはその効果が期待できない。これは、芯部に添加されるＳｉ、Ｃｕ、Ｍｇにおいても全く同様である。これらの元素は、過度に添加した場合にはエッチング時の溶解減量が多くなり、静電容量の低下を来す。
（６）その他にも、特開平４−１２４２３９号公報、特開平４−１２４２４０号公報、特開平７−２３５４５８号公報等にも中高圧用クラッド箔の開示がなされているものの、これらは基本的には薄い外層のアルミニウム箔の中にＭｇやＦｅ系金属間化合物を分散させることにより、ピット開始点の増加を図り、静電容量を増大させることが目的であり、機械的強度という点においてはなお改善すべき余地がある。
発明の開示
前記のように、従来技術では、中高圧用陽極箔の静電容量と機械的強度とを向上させるには限界がある。
従って、本発明は、従来技術と同等以上の静電容量を維持しつつ、高い機械的強度を発現できる電解コンデンサ中高圧陽極用アルミニウム合金箔を提供することを主な目的とする。
本発明者は、従来技術の問題に鑑みて鋭意研究を重ねた結果、特定の構成を有するクラッド箔が上記目的を達成できることを見出し、ついに本発明を完成するに至った。
すなわち、本発明は、アルミニウム外層−アルミニウム芯層−アルミニウム外層の３層からなる電解コンデンサ中高圧陽極用アルミニウム合金クラッド箔であって、
（１）当該芯層の厚さがクラッド箔厚さの２〜３０％であり、
（２）クラッド箔の引張強度が２８Ｎ／ｍｍ２以上であり、
（３）当該外層の立方体方位占有率が８０％以上であり、
（４）直流電解エッチング後において当該芯層を貫通するトンネルピットが存在しない、
ことを特徴とする電解コンデンサ中高圧陽極用アルミニウム合金クラッド箔に係るものである。
以下、本発明の電解コンデンサ中高圧陽極用アルミニウム合金クラッド箔について詳細に説明する。
本発明の電解コンデンサ中高圧陽極用アルミニウム合金クラッド箔は、アルミニウム外層−アルミニウム芯層−アルミニウム外層の３層からなる電解コンデンサ中高圧陽極用アルミニウム合金クラッド箔であって、
（１）当該芯層の厚さがクラッド箔厚さの２〜３０％であり、
（２）クラッド箔の引張強度が２８Ｎ／ｍｍ２以上であり、
（３）当該外層の立方体方位占有率が８０％以上であり、
（４）直流電解エッチング後において当該芯層を貫通するトンネルピットが存在しない、
ことを特徴とする。
本発明クラッド箔は、上記のように、アルミニウム芯層が２つのアルミニウム外層に挟まれた３層構造を有する。以下、上記（１）〜（４）の特徴を順に説明する。
アルミニウム芯層の厚さ
アルミニウム芯層の厚さは、本発明クラッド箔（３層合計）の厚さの通常２〜３０％程度、好ましくは５〜１０％とする。２％未満の場合は、たとえ芯層の強度が高くても、エッチド箔強度の大幅な向上が望めない。３０％を超える場合は、トンネルピットの存在しない部分の割合が多くなり、所望の静電容量が得られなくなる。
また、本発明クラッド箔の厚さは、最終製品の用途等に応じて適宜設定することができるが、通常７０〜１２０μｍ程度、好ましくは７５〜１１５μｍとすれば良い。また、２つのアルミニウム外層の厚さは、互いに同じであっても良いし、異なっていても良い。
クラッド箔の引張強度
本発明クラッド箔の引張強度（すなわち、アルミニウム外層と芯層との複合強度）は、通常２８Ｎ／ｍｍ２以上、好ましくは３０Ｎ／ｍｍ２以上とする。２８Ｎ／ｍｍ２未満の場合は、強度が不十分となり、小径に巻き込むことが困難となる。このような強度は、例えばアルミニウム芯層として適当な厚さの公知の高強度材（Ａｌ材）を使用することにより得られる。なお、この強度は、中高用陽極箔の場合、５００℃近傍で焼鈍された軟質箔の強度に相当するものである。
アルミニウム外層の立方体方位占有率
アルミニウム外層の立方体方位占有率は、通常８０％以上、好ましくは８５％以上、最も好ましくは９０％以上である。８０％未満の場合は、十分な静電容量が得られない。
本発明における立方体方位占有率の算出方法は定法により行った。すなわち、箔を王水系水溶液（塩酸／硝酸／フッ酸＝１８％／３０％／０．１％（水溶液中の体積比））に浸漬し、上記水溶液により腐食された箔表面を画像解析装置で観察し、腐食され難く金属光沢が残る立方体方位粒を黒、腐食され易く乱反射が生じた非立方体方位粒を白とする白黒のコントラストの差としてとらえ、全粒に対する黒い粒の存在割合を算出し、その割合を立方体方位占有率とする。
このような立方体方位占有率は、例えばアルミニウム芯層の厚さの調整、クラッド箔のトータル厚さの制御、アルミニウム芯層の熱処理条件、中間焼鈍の条件、中間焼鈍後の圧延（軽圧延）の採用等によって適宜制御することができる。
トンネルピットの存在
本発明クラッド箔は、これを直流電解エッチングした後においてアルミニウム芯層を貫通するトンネルピットが存在しない。すなわち、本発明クラッド箔では、電解エッチングで形成されるトンネルピットが上記芯層を貫通していない。特に、トンネルピットがアルミニウム芯層に侵入していないことが望ましい。
上記の直流電解エッチング条件は、公知の条件で良いが、少なくとも後記に示す実施例におけるエッチング条件で直流電解エッチングした場合にアルミニウム芯層を貫通するトンネルピットが存在しないことが好ましい。すなわち、少なくとも、塩酸１モル／リットル及び硫酸３モル／リットルの混合水溶液（８０℃）をエッチング液として電流密度３００ｍＡ／ｃｍ２で１２０秒間の第一エッチングを行い、次いで硝酸１．３モル／リットルの水溶液（７５℃）をエッチング液として電流密度２００ｍＡ／ｃｍ２で２２５秒間の第二エッチングを行う直流電解エッチング後において、アルミニウム芯層を貫通するトンネルピットが存在しないことが望ましい。
アルミニウム外層及び芯層の構成成分
本発明クラッド箔は、上記のような特徴を有している限り、上記外層及び芯層の成分（Ａｌ以外の成分）は限定されないが、特に上記外層はＦｅを０．０００５〜０．００５％（好ましくは０．０００６〜０．００３５％、より好ましくは０．０００８〜０．００１２％）含有し、かつ、上記芯層がＭｎ、Ｖ、Ｃｒ、Ｆｅ、Ｔｉ及びＮｉの少なくとも１種を０．３〜５％含有することが望ましい。これらの成分が存在することにより、特に本発明クラッド箔の強度向上をよりいっそう促進することができる。
特に、本発明クラッド箔では、少なくともＭｎが上記芯層に１〜５％（好ましくは１．３〜４．７％）含有することが最も望ましい。この場合も、Ｍｎを含む合計５％を上限として、Ｖ、Ｃｒ、Ｆｅ、Ｔｉ及びＮｉの少なくとも１種（好ましくはＦｅ）を併せて含んでいても良い。
クラッド箔中におけるＣｕ、Ｓｉ及びＰｂ
本発明クラッド箔では、さらにＣｕ、Ｓｉ及びＰｂを含有していることが好ましい。これらの成分が存在することにより、特に本発明クラッド箔の静電容量の向上をよりいっそう促進することができる。この場合、Ｃｕ含有量は通常０．００１５〜０．０１５％（好ましくは０．００２〜０．００８％）、Ｓｉ含有量は通常０．０００５〜０．０１５％（好ましくは０．０００６〜０．００８％）、Ｐｂ含有量は通常０．００００１〜０．００４％（好ましくは０．００００２〜０．０００２％）とすれば良い。
本発明のクラッド箔は、Ｃｕ、Ｓｉ及びＰｂはアルミニウム外層及びアルミニウム芯層の少なくとも一方に存在していれば良いが、いずれの成分もアルミニウム中での拡散速度が速いため、通常は５００℃近傍で焼鈍された後にはいずれの層にも存在することになり、この場合も本発明に包含される。
従って、本発明におけるＣｕ含有量（Ｃ（Ｃｕ））、Ｓｉ含有量（Ｃ（Ｓｉ））及びＰｂ含有量（Ｃ（Ｐｂ））は、それぞれ下記式により示される。
Ｃ（Ｃｕ）＝ｔ１Ｃ１（Ｃｕ）／ｔ０＋（ｔ０−ｔ１）Ｃ２（Ｃｕ）／ｔ０
（但し、ｔ０はクラッド箔の厚さ（μｍ）、ｔ１はアルミニウム芯層の厚さ（μｍ）、Ｃ１（Ｃｕ）はアルミニウム芯層中のＣｕ含有量（重量％）、Ｃ２（Ｃｕ）はアルミニウム外層中のＣｕ含有量（重量％）を示す。）
Ｃ（Ｓｉ）＝ｔ１Ｃ１（Ｓｉ）／ｔ０＋（ｔ０−ｔ１）Ｃ２（Ｓｉ）／ｔ０
（但し、ｔ０はクラッド箔の厚さ（μｍ）、ｔ１はアルミニウム芯層の厚さ（μｍ）、Ｃ１（Ｓｉ）はアルミニウム芯層中のＳｉ含有量（重量％）、Ｃ２（Ｓｉ）はアルミニウム外層中のＳｉ含有量（重量％）を示す。）
Ｃ（Ｐｂ）＝ｔ１Ｃ１（Ｐｂ）／ｔ０＋（ｔ０−ｔ１）Ｃ２（Ｐｂ）／ｔ０
（但し、ｔ０はクラッド箔の厚さ（μｍ）、ｔ１はアルミニウム芯層の厚さ（μｍ）、Ｃ１（Ｐｂ）はアルミニウム芯層中のＰｂ含有量（重量％）、Ｃ２（Ｐｂ）はアルミニウム外層中のＰｂ含有量（重量％）を示す。）
本発明では、特に、Ｐｂは、クラッド箔の表面から深さ０．１μｍまでの表層部におけるＰｂ含有量０．００４〜０．２％で存在していることが好ましい。このようなＰｂ存在状態は、例えば上記Ｐｂ含有量（０．００００１〜０．００４％）をもつクラッド箔を４５０℃以上で熱処理（焼鈍等）することによって得ることができる。
本発明クラッド箔は、上記のような構成が得られる限りは、その製造方法そのものは特に制限されない。従って、特に本発明に規定する組成を除けば、例えば公知のクラッド箔における製造条件・処理条件を適宜採用することによって製造することもできる。まず、所定の組成をもつアルミニウム芯層スラブ及びアルミニウム外層スラブを作製し、これらをそのまま冷間圧延したり、あるいはこれらスラブを積層してソーキングした後、熱間圧延することにより積層体を製造する。また、アルミニウム外層スラブの熱間圧延途中でこれを２分割に切断し、これら２つのアルミニウム外層スラブでアルミニウム芯層スラブを挟み、熱間圧延をさらに進めることによって積層体を得ることも可能である。次いで、これらの積層体を圧延して箔とした後、この箔を不活性ガス（Ａｒガス、Ｎ２ガス等）中で焼鈍すれば、本発明クラッド箔を得ることができる。
このクラッド箔の使用に際しては、公知のクラッド箔と同様の条件にてエッチング処理、化成処理等を行って 使用すれば良い。
エッチング処理では、例えば前記のエッチング条件等を採用することができる。本発明では、本発明クラッド箔を直流電解エッチングされたエッチド箔であって、当該クラッド箔のアルミニウム芯層を貫通するトンネルピットが存在しないことを特徴とするエッチド箔も包含する。
本発明においては、少なくとも、塩酸１モル／リットル及び硫酸３モル／リットルの混合水溶液（８０℃）をエッチング液として電流密度３００ｍＡ／ｃｍ２で１２０秒間の第一エッチングを行い、次いで硝酸１．３モル／リットルの水溶液（７５℃）をエッチング液として電流密度２００ｍＡ／ｃｍ２で２２５秒間の第二エッチングを行う直流電解エッチング後において、アルミニウム芯層を貫通するトンネルピットが存在しないエッチド箔が好ましい。
化成処理では、１５０〜６００Ｖの電圧を印加して箔表面及びトンネルピットの内面に厚さ２００〜１０００ｎｍの酸化皮膜が形成されていることが望ましい。これらの処理が施された化成箔は、最終的には、公知の方法により陰極箔、セパレータ等ともにコンデンサ筒（容器）内に収容すれば良い。
本発明の電解コンデンサ中高圧陽極用アルミニウム合金クラッド箔によれば、従来品と同程度又はそれ以上の静電容量を確保しつつ、従来品りも高い機械的強度を発揮することができる。
これにより、これまで以上に小径に巻き込むことが可能になる結果、コンデンサの小型化に大いに貢献することができる。また、エッチング後の化成処理及び引き続く切断・巻き取り工程等も円滑に行ことができ、生産性の向上にも寄与することができる。
発明を実施するための最良の形態
以下に実施例及び比較例を示し、本発明の特徴をより明確にする。但し、本発明は、これら実施例に限定されるものではない。
実施例１
アルミニウム外層（Ｆｅ／Ｓｉ／Ｃｕ）及びアルミニウム芯層（Ｆｅ／Ｓｉ／Ｃｕ／Ｘ（ＸはＭｎ、Ｖ、Ｃｒ、Ｆｅ、Ｔｉ又はＮｉ））として表１に示す組成のスラブを調製した。各スラブを通常のソーキング、熱間圧延及び冷間圧延に供し、厚さ０．０５〜１ｍｍの板状体とした。これらを外層／芯層／外層の３枚に重ね、空気炉中３００℃にて加熱処理を行い、炉出し後直ちに圧下率５０％で圧延し、三層クラッド材を得た。なお、クラッドを行わない比較箔は、Ｆｅ／Ｓｉ／Ｃｕ＝１０ｐｐｍ／１０ｐｐｍ／５０ｐｐｍのスラブを同様に通常のソーキング、熱間圧延及び冷間圧延に供した。
上記クラッド箔及び比較箔は、厚さ１３０μｍまで冷間圧延し、２００〜３００℃で６時間熱処理した後、１１０μｍの厚さに冷間圧延し、アルゴンガス雰囲気中５００℃で６時間焼鈍し、中高圧用陽極箔とした。
試験例１
得られた箔は、表２に示すエッチング条件で直流電解エッチングを行った後、エッチング前後の重量差により溶解減量を求めるとともに、エッチド箔の折曲強度をＭＩＴ型自動折曲試験器にて測定した。さらに、エッチング後、表２に示す化成条件にて化成処理を施し、８％ホウ酸アンモニウム水溶液中でＬＣＲメーターにより静電容量の測定を行った。
折曲強度は、ＪＩＳＰ８１１５ＭＩＴ型自動折曲試験機にサンプルを取り付け、表３に示す条件で試験片が破断するまでの折曲回数で評価した。なお、折り曲げは、９０度曲げる工程を第１回とし、もとに戻す工程を第２回とし、さらに逆方向に９０度曲げる工程を第３回とし、もとに戻す工程を第４回という１サイクルを４回と数えた。第５回以降は、ふたたび上記第１回から同じ工程を繰り返し行う。
表４にクラッド箔の作製条件、クラッド箔の芯材比率、引張強度、立方体方位占有率、エッチング時の溶解減量、エッチド箔の折曲強度及び化成後の静電容量をそれぞれ示す。なお、表４中、溶解減量及び静電容量は、クラッドしていない厚さ１１０μｍの比較箔の結果を１００とした場合の相対値で示す。
試験例１で直流電解エッチングされた各試料（エッチド箔）について、試料断面（６００倍）及び表面（トンネルピットの断面）（１０００倍）の電子顕微鏡による観察を行った。その結果、本発明品はいずれもアルミニウム芯層を貫通するトンネルピットの存在は認められなかった。これに対し、比較品は、トンネルピットがアルミニウム芯層を貫通していることが確認された。
図１には、実施例の試料２（本発明品（ａ））と試料１（比較品（ｂ））の断面（イメージ図）をそれぞれ示す。図２には、実施例の試料２（本発明品（ａ））と試料１（比較品（ｂ））の電解研磨後の表面（イメージ図）をそれぞれ示す。
図１からも明らかなように、本発明品は、トンネルピットの伸長がほぼ均一に停止し、アルミニウム芯層が明確に存在していることがわかる。すなわち、アルミニウム芯層を貫通するトンネルピットが全く存在していないことがわかる。これに対し、比較品は、アルミニウム芯層を貫通するトンネルピットが見られるだけでなく、トンネルピット先端が不均一であり、アルミニウム芯層の厚さが一定していないことがわかる。
また、図２より、本発明品では、ピット密度が比較品よりも高く、かつ、均一にピットが存在していることがわかる。
【図面の簡単な説明】
図１は、実施例の試料２（本発明品（ａ））と試料１（比較品（ｂ））の断面（イメージ図）をそれぞれ示す。
図２は、実施例の試料２（本発明品（ａ））と試料１（比較品（ｂ））の電解研磨後の表面（イメージ図）をそれぞれ示す。 TECHNICAL FIELD The present invention relates to an aluminum alloy foil for an electrolytic capacitor anode, particularly to an aluminum clad foil having three layers. More specifically, the present invention relates to an aluminum alloy foil for a high-pressure anode in an electrolytic capacitor that has high electrostatic capacity and high mechanical strength after DC electrolytic etching.
In the present invention, “%” and “ppm” mean “wt%” and “wt ppm”, respectively.
BACKGROUND ART Generally, an aluminum alloy foil for an anode for high voltage in an electrolytic capacitor has a high purity of 99.98% or more by suppressing the inclusion of impurities Fe and Si as much as possible and adding a small amount of Cu as necessary. Pure aluminum foil is used. Since the capacitance as a capacitor is proportional to its surface area, the aluminum alloy foil is subjected to electrochemical etching in an acidic solution such as hydrochloric acid to enlarge the surface. An aluminum oxide film (chemical conversion film) having a withstand voltage is formed by subsequent anodic oxidation on the aluminum foil (etched foil) whose surface has been enlarged by etching. This is called a chemical conversion process, and the formed etched foil is called a chemical conversion foil. Next, this chemical conversion foil is wound together with separator paper impregnated with an electrolytic solution and a cathode foil and accommodated in a capacitor cylinder (container).
The medium- and high-pressure aluminum foil for anodes has a required withstand voltage of about 200 V or more, and the chemical film after etching is thick (about 2500 mm or more), so that the diameter of the etching pit is not blocked by the chemical film during the formation. A tunnel shape of about 1 μm is formed by DC electrolytic etching in an acidic solution in the presence of chlorine ions. Etching pits formed in this manner are generally called tunnel pits.
Recently, there has been an increasing demand for miniaturization of electronic devices, and capacitors are no exception. For this reason, the aluminum foil for an electrode used for a capacitor has a high mechanical strength in the etched foil in order to enclose the etched foil small as well as having a high capacitance per unit area, that is, a surface expansion ratio after etching. Required.
Under such demands, improvements have been promoted from the aspect of etching methods. Conventionally, the penetration type DC etching method mainly composed of hydrochloric acid has been adopted to increase the surface expansion ratio of the medium- and high-pressure anode foil. However, in order to obtain a higher-strength etched foil, a core in which sulfuric acid is added to hydrochloric acid is used. The remaining type DC etching has been developed to improve the strength of the etched foil.
Here, the penetration type etching is an etching method in which tunnel pits are generated by penetrating in the cross-sectional direction perpendicular to the foil surface. Since pits exist over almost the entire cross section of the foil, the surface expansion ratio is high, but the mechanical strength of the etched foil is low. On the other hand, the core residue type etching is an etching method in which the tunnel pits are generated perpendicular to the foil surface in the same manner as the penetration type, but the progress of the pits is stopped halfway in the cross-sectional direction of the foil. Since there is an unetched portion in the vicinity of the center, the mechanical strength is excellent compared to the penetration type.
However, the improvement in capacitance and the improvement in strength are related to each other, and it is inevitably necessary to increase the number of pits or increase the thickness of the unetched portion of the core to increase the capacitance. Strength will fall. If the strength is reduced, not only is it difficult to accommodate in a small capacitor cylinder, but also foil breakage occurs in the chemical conversion process after the etching process, or in the cutting process / winding process of the chemical conversion foil, and the productivity is significantly reduced. It will be.
So far, technologies that employ a clad foil as an aluminum foil for electrolytic capacitors have been proposed as follows, but there is still room for improvement in order to put them into practical use.
(1) For example, in Japanese Patent Laid-Open No. 49-10366, a core aluminum foil having substantially the same purity as the coated aluminum is crossed between the coated aluminum foil and the rolling direction between two high-purity aluminums of 99.9% or more. Aluminum foil for electrolytic capacitor integrated by interposing an aluminum foil slightly lower in purity than coated aluminum between two sheets of high-purity coated aluminum of 99.9% or more. A foil is disclosed.
However, in this technique, in order to increase the mechanical strength, the ratio of the thickness of the core aluminum material to the total thickness of the aluminum foil (cladding ratio) must be increased, and the lower limit is limited. That is, the capacitance is sacrificed as much as the cladding ratio must be increased.
(2) Japanese Patent Application Laid-Open No. 55-77986 discloses a relatively low-purity aluminum-based alloy core having an iron and silicon content of 0.03% or more, and iron clad on both sides of the core. A composite aluminum foil for an electrolytic capacitor is made of a relatively high purity aluminum-based alloy having a silicon content of 0.2% or less, and the thickness of the cladding layer is 20% or less of the thickness of the composite on one side. It is disclosed.
Japanese Patent Laid-Open No. 62-47110 discloses a clad foil in which a core layer made of less than 99.4% aluminum alloy is interposed between two outer layers of 99.98% or more.
However, these techniques are also developed as low-pressure anode foils on the premise of AC etching, and cannot be used as medium-high pressure anode foils as they are. That is, neither the mechanical strength nor the capacitance of the etched foil can be improved sufficiently.
(3) Japanese Patent Publication No. 2-58765 discloses a cubic orientation in which an aluminum core layer having a purity of 99.995% or more is clad on both surfaces of the core layer with an aluminum outer layer having a purity of 99.0 to 99.99%. An aluminum alloy foil for electrolytic capacitor electrodes rich in crystals is disclosed.
However, this technique is only aimed at improving the cube orientation occupation ratio and thus increasing the capacitance, and cannot improve the mechanical strength. That is, there is a need for further improvement in order to improve the capacitance and mechanical strength at the same time.
(4) Japanese Unexamined Patent Publication No. 4-120235 discloses a foil having a non-cubic orientation occupancy of 40% or more between two aluminum outer layers having an aluminum purity of 99.9% or more and a cube orientation occupancy of 80% or more. An aluminum foil for electrolytic capacitor electrodes formed by cladding is disclosed.
However, this technique only uses the fact that the extension of the tunnel pit stops when the cube orientation of the core material is low, and has not yet improved the electrostatic capacity and the mechanical strength at the same time.
(5) Japanese Unexamined Patent Publication No. 4-120234 discloses an electrolytic capacitor in which a core material is clad with aluminum containing one or more of Zn, In, Sn, and Pb, and an outer layer is clad with 99.9% or more of aluminum. An aluminum foil for electrodes is disclosed.
However, Zn, In, Sn, Pb, and the like have a high diffusion rate in aluminum, and the effect cannot be expected when annealing is performed in the vicinity of 500 ° C. like a medium-high pressure anode foil. The same applies to Si, Cu, and Mg added to the core. When these elements are added excessively, the dissolution loss during etching increases, resulting in a decrease in capacitance.
(6) In addition, although disclosed in Japanese Patent Laid-Open No. 4-124239, Japanese Patent Laid-Open No. 4-124240, Japanese Patent Laid-Open No. 7-235458, etc., these are basically disclosed. The purpose is to increase the pit start point and increase the capacitance by dispersing Mg or Fe intermetallic compound in a thin outer aluminum foil. In terms of mechanical strength, There is still room for improvement.
DISCLOSURE OF THE INVENTION As described above, in the prior art, there is a limit in improving the electrostatic capacity and mechanical strength of the medium-high voltage anode foil.
Therefore, the main object of the present invention is to provide an aluminum alloy foil for an electrolytic capacitor high-pressure anode that can exhibit high mechanical strength while maintaining a capacitance equal to or higher than that of the prior art.
As a result of intensive studies in view of the problems of the prior art, the present inventor found that a clad foil having a specific configuration can achieve the above object, and finally completed the present invention.
That is, the present invention is an aluminum alloy clad foil for a high-pressure anode in an electrolytic capacitor comprising three layers of an aluminum outer layer-aluminum core layer-aluminum outer layer,
(1) The thickness of the core layer is 2 to 30% of the clad foil thickness,
(2) The tensile strength of the clad foil is 28 N / mm 2 or more,
(3) The cube orientation occupation ratio of the outer layer is 80% or more,
(4) There is no tunnel pit penetrating the core layer after direct current electrolytic etching,
The present invention relates to an aluminum alloy clad foil for a high-pressure anode in an electrolytic capacitor.
Hereinafter, the aluminum alloy clad foil for high-pressure anodes in electrolytic capacitors of the present invention will be described in detail.
The aluminum alloy clad foil for high-pressure anodes in electrolytic capacitors of the present invention is an aluminum alloy clad foil for high-pressure anodes in electrolytic capacitors consisting of three layers of an aluminum outer layer, an aluminum core layer, and an aluminum outer layer,
(1) The thickness of the core layer is 2 to 30% of the clad foil thickness,
(2) The tensile strength of the clad foil is 28 N / mm 2 or more,
(3) The cube orientation occupation ratio of the outer layer is 80% or more,
(4) There is no tunnel pit penetrating the core layer after direct current electrolytic etching,
It is characterized by that.
The clad foil of the present invention has a three-layer structure in which an aluminum core layer is sandwiched between two aluminum outer layers as described above. Hereinafter, the features (1) to (4) will be described in order.
Thickness of aluminum core layer The thickness of the aluminum core layer is usually about 2 to 30%, preferably 5 to 10% of the thickness of the clad foil of the present invention (total of 3 layers). If it is less than 2%, a significant improvement in the strength of the etched foil cannot be expected even if the strength of the core layer is high. If it exceeds 30%, the proportion of the portion where there is no tunnel pit increases, and the desired capacitance cannot be obtained.
Moreover, although the thickness of this invention clad foil can be suitably set according to the use etc. of a final product, it is usually about 70-120 micrometers, Preferably what is necessary is just to be 75-115 micrometers. The thicknesses of the two aluminum outer layers may be the same or different from each other.
Tensile strength <br/> tensile strength of the present invention clad foil clad foil (i.e., the composite strength of the aluminum outer layer and the core layer) is usually 28N / mm 2 or more, preferably 30 N / mm 2 or more. When it is less than 28 N / mm 2 , the strength is insufficient, and it is difficult to entrain to a small diameter. Such strength can be obtained, for example, by using a known high-strength material (Al material) having an appropriate thickness as the aluminum core layer. This strength corresponds to the strength of the soft foil annealed at around 500 ° C. in the case of the medium-high anode foil.
Cube orientation occupation ratio of aluminum outer layer The cube orientation occupation ratio of the aluminum outer layer is usually 80% or more, preferably 85% or more, and most preferably 90% or more. If it is less than 80%, sufficient electrostatic capacity cannot be obtained.
The calculation method of the cube orientation occupation rate in the present invention was performed by a conventional method. That is, the foil was immersed in an aqua regia aqueous solution (hydrochloric acid / nitric acid / hydrofluoric acid = 18% / 30% / 0.1% (volume ratio in the aqueous solution)), and the foil surface corroded by the aqueous solution was image-analyzed. Observe and calculate the ratio of black grains to all grains as a difference in black and white contrast where black is a cubic grain that is hard to be corroded and has a metallic luster and white is a non-cubic grain that is easily corroded and irregularly reflected. The ratio is defined as the cube orientation occupation ratio.
Such cube orientation occupancy is, for example, adjustment of the thickness of the aluminum core layer, control of the total thickness of the clad foil, heat treatment conditions of the aluminum core layer, conditions of intermediate annealing, rolling after intermediate annealing (light rolling) It can be appropriately controlled depending on the employment.
Presence of tunnel pits The clad foil of the present invention does not have tunnel pits penetrating the aluminum core layer after DC electrolytic etching of the clad foil. That is, in the clad foil of the present invention, tunnel pits formed by electrolytic etching do not penetrate the core layer. In particular, it is desirable that tunnel pits do not penetrate the aluminum core layer.
The DC electrolytic etching conditions may be known conditions, but it is preferable that tunnel pits penetrating the aluminum core layer do not exist when DC electrolytic etching is performed at least under the etching conditions in the examples described later. That is, first etching is performed for 120 seconds at a current density of 300 mA / cm 2 using at least a mixed aqueous solution (80 ° C.) of
Components of aluminum outer layer and core layer As long as the clad foil of the present invention has the above-described characteristics, the components of the outer layer and the core layer (components other than Al) are not limited. The outer layer contains Fe in an amount of 0.0005 to 0.005% (preferably 0.0006 to 0.0035%, more preferably 0.0008 to 0.0012%), and the core layer has Mn, V, Cr It is desirable to contain 0.3 to 5% of at least one of Fe, Ti and Ni. The presence of these components can further promote the strength improvement of the clad foil of the present invention.
In particular, in the clad foil of the present invention, it is most desirable that at least Mn is contained in the core layer in an amount of 1 to 5% (preferably 1.3 to 4.7%). Also in this case, at least one of V, Cr, Fe, Ti, and Ni (preferably Fe) may be included together, with the upper limit being 5% including Mn.
Cu, Si and Pb in the clad foil
The clad foil of the present invention preferably further contains Cu, Si and Pb. The presence of these components can further promote the improvement of the capacitance of the clad foil of the present invention. In this case, the Cu content is usually 0.0015 to 0.015% (preferably 0.002 to 0.008%), and the Si content is usually 0.0005 to 0.015% (preferably 0.0006 to 0). 0.008%), and the Pb content is usually 0.00001 to 0.004% (preferably 0.00002 to 0.0002%).
In the clad foil of the present invention, Cu, Si, and Pb may be present in at least one of the aluminum outer layer and the aluminum core layer, but since any component has a high diffusion rate in aluminum, it is usually around 500 ° C. After being annealed with, it exists in any layer, and this case is also included in the present invention.
Therefore, the Cu content (C (Cu)), the Si content (C (Si)), and the Pb content (C (Pb)) in the present invention are represented by the following formulas, respectively.
C (Cu) = t 1 C 1 (Cu) / t 0 + (t 0 −t 1 ) C 2 (Cu) / t 0
(Where t 0 is the thickness of the clad foil (μm), t 1 is the thickness of the aluminum core layer (μm), C 1 (Cu) is the Cu content (% by weight) in the aluminum core layer, C 2 ( Cu) indicates the Cu content (% by weight) in the outer aluminum layer.)
C (Si) = t 1 C 1 (Si) / t 0 + (t 0 −t 1 ) C 2 (Si) / t 0
(Where t 0 is the thickness of the clad foil (μm), t 1 is the thickness of the aluminum core layer (μm), C 1 (Si) is the Si content (wt%) in the aluminum core layer, C 2 ( Si) indicates the Si content (wt%) in the outer aluminum layer.
C (Pb) = t 1 C 1 (Pb) / t 0 + (t 0 −t 1 ) C 2 (Pb) / t 0
(Where t 0 is the thickness of the clad foil (μm), t 1 is the thickness of the aluminum core layer (μm), C 1 (Pb) is the Pb content (wt%) in the aluminum core layer, C 2 ( Pb) indicates the Pb content (% by weight) in the aluminum outer layer.
In the present invention, it is particularly preferable that Pb is present at a Pb content of 0.004 to 0.2% in the surface layer portion from the surface of the clad foil to a depth of 0.1 μm. Such a Pb existence state can be obtained, for example, by heat-treating (eg, annealing) a clad foil having the Pb content (0.00001 to 0.004%) at 450 ° C. or higher.
The manufacturing method itself of the clad foil of the present invention is not particularly limited as long as the above configuration is obtained. Therefore, except for the composition specified in the present invention, for example, it can be produced by appropriately adopting the production conditions and processing conditions of a known clad foil. First, an aluminum core layer slab having a predetermined composition and an aluminum outer layer slab are produced, and these are cold-rolled as they are, or these slabs are laminated and soaked, and then hot-rolled to produce a laminate. . It is also possible to obtain a laminate by cutting the aluminum outer layer slab into two parts during hot rolling, sandwiching the aluminum core layer slab with these two aluminum outer layer slabs, and further proceeding with hot rolling. . Subsequently, after rolling these laminated bodies into foils, if the foil is annealed in an inert gas (Ar gas, N 2 gas, etc.), the clad foil of the present invention can be obtained.
When this clad foil is used, it may be used after being subjected to an etching treatment, a chemical conversion treatment, or the like under the same conditions as those of a known clad foil.
In the etching process, for example, the above-described etching conditions can be employed. The present invention also includes an etched foil obtained by subjecting the clad foil of the present invention to direct current electrolytic etching and having no tunnel pits penetrating the aluminum core layer of the clad foil.
In the present invention, the first etching is performed for 120 seconds at a current density of 300 mA / cm 2 using at least a mixed aqueous solution (80 ° C.) of
In the chemical conversion treatment, it is desirable that a voltage of 150 to 600 V is applied to form an oxide film having a thickness of 200 to 1000 nm on the foil surface and the inner surface of the tunnel pit. The chemical conversion foil subjected to these treatments may be finally stored in a capacitor cylinder (container) together with a cathode foil, a separator and the like by a known method.
According to the aluminum alloy clad foil for a high-pressure anode in an electrolytic capacitor of the present invention, the conventional product can exhibit high mechanical strength while securing the same or higher capacitance as the conventional product.
As a result, it is possible to wind up with a smaller diameter than before, and as a result, it can greatly contribute to the downsizing of the capacitor. In addition, the chemical conversion treatment after etching and the subsequent cutting and winding processes can be performed smoothly, which can contribute to the improvement of productivity.
BEST MODE FOR CARRYING OUT THE INVENTION The features of the present invention will be made clearer with the following examples and comparative examples. However, the present invention is not limited to these examples.
Example 1
Slabs having the compositions shown in Table 1 were prepared as an aluminum outer layer (Fe / Si / Cu) and an aluminum core layer (Fe / Si / Cu / X (X is Mn, V, Cr, Fe, Ti, or Ni)). Each slab was subjected to normal soaking, hot rolling and cold rolling to form a plate-like body having a thickness of 0.05 to 1 mm. These were layered on the outer layer / core layer / outer layer, heat-treated at 300 ° C. in an air furnace, and rolled immediately after rolling out at a reduction rate of 50% to obtain a three-layer clad material. In addition, the comparative foil which does not carry out clad | crud used the normal soaking, hot rolling, and cold rolling for the slab of Fe / Si / Cu = 10ppm / 10ppm / 50ppm similarly.
The clad foil and the comparative foil are cold-rolled to a thickness of 130 μm, heat-treated at 200 to 300 ° C. for 6 hours, then cold-rolled to a thickness of 110 μm, and annealed in an argon gas atmosphere at 500 ° C. for 6 hours. An anode foil for medium and high pressure was obtained.
Test example 1
The obtained foil was subjected to direct current electrolytic etching under the etching conditions shown in Table 2, and then the dissolution loss was determined by the weight difference before and after etching, and the bending strength of the etched foil was measured with an MIT type automatic bending tester. did. Furthermore, after the etching, chemical conversion treatment was performed under the chemical conversion conditions shown in Table 2, and the capacitance was measured with an LCR meter in an 8% ammonium borate aqueous solution.
The bending strength was evaluated based on the number of bendings until the specimen was broken under the conditions shown in Table 3 after attaching the sample to a JISP8115MIT type automatic bending tester. In addition, the bending process is referred to as the first process, the second process is the process of bending 90 degrees, the third process is the process of bending 90 degrees in the opposite direction, and the fourth process is the process of returning to the original process. One cycle was counted as 4 times. After the fifth time, the same process is repeated from the first time.
Table 4 shows the production conditions of the clad foil, the core material ratio of the clad foil, the tensile strength, the cube orientation occupation ratio, the dissolution loss during etching, the bending strength of the etched foil, and the capacitance after formation. In Table 4, the dissolution weight loss and the electrostatic capacity are shown as relative values when the result of a comparative foil having a thickness of 110 μm which is not clad is 100.
Each sample (etched foil) subjected to DC electrolytic etching in Test Example 1 was observed with an electron microscope on the sample cross section (600 times) and the surface (tunnel pit cross section) (1000 times). As a result, none of the products of the present invention was found to have tunnel pits penetrating the aluminum core layer. On the other hand, in the comparative product, it was confirmed that the tunnel pit penetrated the aluminum core layer.
In FIG. 1, the cross section (image figure) of the sample 2 (product (a) of this invention) and the sample 1 (comparison product (b)) of an Example is each shown. In FIG. 2, the surface (image figure) after the electrolytic polishing of sample 2 (product of the present invention (a)) and sample 1 (comparative product (b)) of the example is shown.
As can be seen from FIG. 1, in the product of the present invention, it is understood that the elongation of the tunnel pits stops almost uniformly and the aluminum core layer is clearly present. That is, it can be seen that there are no tunnel pits penetrating the aluminum core layer. On the other hand, it can be seen that the comparative product not only shows tunnel pits penetrating the aluminum core layer, but also has uneven tunnel pit tips and the thickness of the aluminum core layer is not constant.
Further, it can be seen from FIG. 2 that the pit density is higher in the product of the present invention than in the comparative product, and pits exist uniformly.
[Brief description of the drawings]
FIG. 1 shows a cross section (image diagram) of Sample 2 (Product (a) of the present invention) and Sample 1 (Comparative product (b)) of Examples.
FIG. 2 shows the surface (image diagram) after electrolytic polishing of sample 2 (product of the present invention (a)) and sample 1 (comparative product (b)) of the example.
Claims (7)
（１）当該芯層の厚さがクラッド箔厚さの２〜３０％であり、
（２）クラッド箔の引張強度が２８Ｎ／ｍｍ２以上であり、
（３）当該外層の立方体方位占有率が８０％以上であり、
（４）直流電解エッチング後において当該芯層を貫通するトンネルピットが存在せず、
当該アルミニウム外層がＦｅを０．０００５〜０．００５％含有し、かつ、アルミニウム芯層がＭｎ、Ｖ、Ｃｒ、Ｆｅ、Ｔｉ及びＮｉの少なくとも１種を０．３〜５％含有する
ことを特徴とする電解コンデンサ中高圧陽極用アルミニウム合金クラッド箔。An aluminum alloy clad foil for a high-pressure anode in an electrolytic capacitor comprising three layers of an aluminum outer layer-aluminum core layer-aluminum outer layer,
(1) The thickness of the core layer is 2 to 30% of the clad foil thickness,
(2) The tensile strength of the clad foil is 28 N / mm 2 or more,
(3) The cube orientation occupation ratio of the outer layer is 80% or more,
(4) There is no tunnel pit that penetrates the core layer after DC electrolytic etching,
The outer aluminum layer contains 0.0005 to 0.005% Fe, and the aluminum core layer contains 0.3 to 5% of at least one of Mn, V, Cr, Fe, Ti and Ni. An aluminum alloy clad foil for high-pressure anodes in electrolytic capacitors.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34890099 | 1999-12-08 | ||
| PCT/JP2000/008724 WO2001043150A1 (en) | 1999-12-08 | 2000-12-08 | Aluminum alloy clad foil for intermediate- and high-voltage anode of electrolytic capacitor |
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| JP4428902B2 true JP4428902B2 (en) | 2010-03-10 |
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| WO (1) | WO2001043150A1 (en) |
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| WO2023117299A3 (en) * | 2021-12-23 | 2023-08-03 | Tdk Electronics Ag | Coupled etching and deposition process and capacitor foil formed by the process |
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| CN101329954B (en) * | 2008-07-14 | 2011-05-25 | 钰邦电子（无锡）有限公司 | Chip-shaped solid electrolytic capacitor |
| CN110033947B (en) * | 2019-05-13 | 2020-12-29 | 南通海星电子股份有限公司 | High-strength electronic optical foil and manufacturing process thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS51113154A (en) * | 1975-03-28 | 1976-10-06 | Toyo Aluminium Kk | Aluminum foil for elecrolytic capacitor electrode |
| US4214041A (en) * | 1978-12-01 | 1980-07-22 | Swiss Aluminium Ltd. | Composite aluminum capacitor foil |
| JPS57194516A (en) * | 1981-05-26 | 1982-11-30 | Toyo Aluminium Kk | Aluminum foil for electrolytic condenser |
| JPS63288008A (en) * | 1987-05-20 | 1988-11-25 | Sumitomo Light Metal Ind Ltd | Aluminum foil for electrolytic capacitor |
| JP2627456B2 (en) * | 1990-03-08 | 1997-07-09 | 住友軽金属工業 株式会社 | Aluminum foil for electrolytic capacitors |
| JP3051436B2 (en) * | 1990-09-10 | 2000-06-12 | 昭和アルミニウム株式会社 | Method for producing aluminum foil for electrolytic capacitor electrode |
| JPH04120234A (en) * | 1990-09-10 | 1992-04-21 | Showa Alum Corp | Aluminum foil for electrode of electrolytic capacitor |
| JP3312913B2 (en) * | 1991-01-25 | 2002-08-12 | 昭和電工株式会社 | Aluminum foil for electrode of electrolytic capacitor |
| JPH04250613A (en) * | 1991-01-25 | 1992-09-07 | Showa Alum Corp | Aluminum foil for electrolytic capacitor electrode |
| JP3252313B2 (en) * | 1995-03-28 | 2002-02-04 | 日本蓄電器工業株式会社 | Etching method of aluminum foil for electrolytic capacitor |
-
2000
- 2000-12-08 JP JP2001543748A patent/JP4428902B2/en not_active Expired - Fee Related
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| WO2023117299A3 (en) * | 2021-12-23 | 2023-08-03 | Tdk Electronics Ag | Coupled etching and deposition process and capacitor foil formed by the process |
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