JP4976642B2 - High crystalline silver powder and method for producing the same - Google Patents
High crystalline silver powder and method for producing the same Download PDFInfo
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- JP4976642B2 JP4976642B2 JP2004034121A JP2004034121A JP4976642B2 JP 4976642 B2 JP4976642 B2 JP 4976642B2 JP 2004034121 A JP2004034121 A JP 2004034121A JP 2004034121 A JP2004034121 A JP 2004034121A JP 4976642 B2 JP4976642 B2 JP 4976642B2
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- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims description 187
- 238000004519 manufacturing process Methods 0.000 title claims description 32
- 239000007864 aqueous solution Substances 0.000 claims description 118
- 239000002245 particle Substances 0.000 claims description 48
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 48
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims description 44
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 33
- 229910017604 nitric acid Inorganic materials 0.000 claims description 33
- 238000009826 distribution Methods 0.000 claims description 28
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 24
- 229960005070 ascorbic acid Drugs 0.000 claims description 22
- 235000010323 ascorbic acid Nutrition 0.000 claims description 21
- 239000011668 ascorbic acid Substances 0.000 claims description 21
- 229920000159 gelatin Polymers 0.000 claims description 21
- 239000002270 dispersing agent Substances 0.000 claims description 20
- 108010010803 Gelatin Proteins 0.000 claims description 19
- 239000008273 gelatin Substances 0.000 claims description 19
- 235000019322 gelatine Nutrition 0.000 claims description 19
- 235000011852 gelatine desserts Nutrition 0.000 claims description 19
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 19
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 19
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 19
- 238000002156 mixing Methods 0.000 claims description 17
- 230000001186 cumulative effect Effects 0.000 claims description 5
- 238000000691 measurement method Methods 0.000 claims description 3
- 229910052709 silver Inorganic materials 0.000 description 39
- 239000004332 silver Substances 0.000 description 39
- 239000000758 substrate Substances 0.000 description 31
- 239000011259 mixed solution Substances 0.000 description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 24
- 239000000919 ceramic Substances 0.000 description 20
- 238000000034 method Methods 0.000 description 16
- 239000000203 mixture Substances 0.000 description 16
- 239000011248 coating agent Substances 0.000 description 10
- 238000000576 coating method Methods 0.000 description 10
- 238000010304 firing Methods 0.000 description 9
- 238000011049 filling Methods 0.000 description 8
- 239000012535 impurity Substances 0.000 description 7
- 238000003756 stirring Methods 0.000 description 7
- 239000012065 filter cake Substances 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 239000008188 pellet Substances 0.000 description 5
- 239000006228 supernatant Substances 0.000 description 5
- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical compound [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000008602 contraction Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 239000011164 primary particle Substances 0.000 description 3
- 238000007639 printing Methods 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 238000013329 compounding Methods 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 239000002241 glass-ceramic Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000012046 mixed solvent Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000000790 scattering method Methods 0.000 description 2
- -1 silver ions Chemical class 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 229910021642 ultra pure water Inorganic materials 0.000 description 2
- 239000012498 ultrapure water Substances 0.000 description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 1
- 235000000069 L-ascorbic acid Nutrition 0.000 description 1
- 239000002211 L-ascorbic acid Substances 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- WUOACPNHFRMFPN-UHFFFAOYSA-N alpha-terpineol Chemical compound CC1=CCC(C(C)(C)O)CC1 WUOACPNHFRMFPN-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- SQIFACVGCPWBQZ-UHFFFAOYSA-N delta-terpineol Natural products CC(C)(O)C1CCC(=C)CC1 SQIFACVGCPWBQZ-UHFFFAOYSA-N 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- YWXYYJSYQOXTPL-SLPGGIOYSA-N isosorbide mononitrate Chemical compound [O-][N+](=O)O[C@@H]1CO[C@@H]2[C@@H](O)CO[C@@H]21 YWXYYJSYQOXTPL-SLPGGIOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000010079 rubber tapping Methods 0.000 description 1
- UQDJGEHQDNVPGU-UHFFFAOYSA-N serine phosphoethanolamine Chemical compound [NH3+]CCOP([O-])(=O)OCC([NH3+])C([O-])=O UQDJGEHQDNVPGU-UHFFFAOYSA-N 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 229940116411 terpineol Drugs 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/07—Metallic powder characterised by particles having a nanoscale microstructure
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12014—All metal or with adjacent metals having metal particles
Description
本発明は、高結晶性銀粉及びその製造方法に関し、詳しくは、例えば、チップ部品、プラズマディスプレイパネル等の電極や回路を、大幅にファイン化し、高密度及び高精度で且つ高信頼性をもって形成することができる導電性ペースト、特に微細な配線又は薄層で平滑な塗膜等を高密度及び高精度で且つ高信頼性をもって形成することができる導電性ペーストの製造に好ましい、微粒で、分散性がよく、粒度分布がシャープすぎず比較的ブロードであり、結晶子が大きいため、導電性ペーストの原料として用いた場合に、ペーストへの銀粉の分散性及び導電性ペーストにおける銀粉の充填性に優れ、銀厚膜から形成される電極や回路等をよりファイン化することができ、導電性ペーストから得られる銀厚膜が耐熱収縮性に優れると共に比抵抗（抵抗率）の低いものとすることができる高結晶性銀粉及びその製造方法に関するものである。 The present invention relates to highly crystalline silver powder and a method for producing the same, and more specifically, for example, electrodes and circuits such as chip parts and plasma display panels are significantly refined and formed with high density, high accuracy, and high reliability. Conductive paste that can be formed, especially fine wiring or thin and smooth coating film etc., which is preferable for the production of conductive paste that can be formed with high density, high precision and high reliability, fine and dispersible The particle size distribution is not too sharp and relatively broad, and the crystallites are large, so when used as a raw material for conductive paste, it excels in the dispersibility of silver powder in the paste and the filling ability of silver powder in the conductive paste. Electrodes and circuits formed from silver thick films can be made finer, and silver thick films obtained from conductive paste have excellent heat shrinkage resistance and specific resistance. It relates highly crystalline silver powder and a manufacturing method thereof can be made low (resistivity).
従来、電子部品等の電極や回路を形成する方法として、導電性材料である銀粉をペーストに分散させた導電性ペーストを基板に印刷した後、該ペーストを焼成又はキュアリングし硬化させて銀厚膜を形成することにより回路を形成する方法が知られている。しかし、近年、電子機器の高機能化により電子デバイスの小型高密度化が求められており、このため、導電性ペーストの材料である銀粉にも、導電性ペーストとしたときに微粒でありながら充填性や分散性に優れていることが望まれるようになってきている。なお、本発明において分散性とは、ペーストへの銀粉の分散性のように特に断らない限り、銀粉の一次粒子同士の凝集し難さを意味する。例えば、分散性がよい状態とは一次粒子同士の凝集している割合が少ない又は全くない状態をいい、分散性が悪い状態とは一次粒子同士が凝集している割合が多い又は全て凝集している状態をいう。 Conventionally, as a method of forming electrodes and circuits of electronic parts, etc., after printing a conductive paste in which silver powder as a conductive material is dispersed in a paste on a substrate, the paste is baked or cured and cured to obtain a silver thickness A method of forming a circuit by forming a film is known. However, in recent years, there has been a demand for smaller and higher density electronic devices due to higher functionality of electronic devices. For this reason, silver powder, which is a material of conductive paste, is filled with fine particles when used as a conductive paste. It is becoming desirable to have excellent properties and dispersibility. In the present invention, dispersibility means that the primary particles of silver powder are not easily aggregated unless otherwise specified, such as dispersibility of silver powder in a paste. For example, a state in which dispersibility is good means a state in which the proportion of primary particles aggregated is small or not at all, and a state in which dispersibility is poor means that the proportion of primary particles agglomerated is large or all aggregates. The state that is.
上記導電性ペーストが印刷される基板としては、通常はセラミック基板においてＩＣのパッケージ等の発熱が大きい部分等に用いられている。しかし、このセラミック基板に導電性ペーストを印刷する場合には、セラミック基板の熱収縮率と印刷した導電性ペーストから生成される銀厚膜の熱収縮率とが一般的に異なるため、焼成時においてセラミック基板と銀厚膜とが剥離したり基板自体が変形したりするおそれがある。このため、セラミック基板の熱収縮率と印刷した導電性ペーストから形成される銀厚膜の熱収縮率とは、なるべく近い値を採るものであることが好ましい。 As a substrate on which the conductive paste is printed, it is usually used for a portion of a ceramic substrate where heat generation is large such as an IC package. However, when printing a conductive paste on this ceramic substrate, the thermal shrinkage rate of the ceramic substrate and the thermal shrinkage rate of the thick silver film produced from the printed conductive paste are generally different, There is a possibility that the ceramic substrate and the silver thick film are peeled off or the substrate itself is deformed. For this reason, it is preferable that the thermal contraction rate of the ceramic substrate and the thermal contraction rate of the silver thick film formed from the printed conductive paste are as close as possible.
このような焼成時における上記銀厚膜の熱収縮の一因としては、導電性ペースト中の銀粉が焼成時に焼結を起こすことにあるものと考えられている。すなわち、銀粉は微小な結晶子から構成される多結晶体であり、銀粉を含む導電性ペーストを銀厚膜の形成のために焼成する際に銀粉中の微小な結晶子が焼結して、銀厚膜の生成前後で寸法変化が生じ熱収縮を起こすものと考えられる。このため、熱収縮の少ない銀粉含有導電性ペーストを得るには、結晶子の焼結がなるべく生じないように、銀粉中の結晶子はできるだけ大きいものであることが望ましい。 One cause of the thermal contraction of the thick silver film during firing is considered to be that the silver powder in the conductive paste undergoes sintering during firing. That is, silver powder is a polycrystal composed of fine crystallites, and when the conductive paste containing silver powder is baked to form a thick silver film, the fine crystallites in the silver powder are sintered, It is considered that a dimensional change occurs before and after the formation of the silver thick film, causing heat shrinkage. For this reason, in order to obtain a silver powder-containing conductive paste with little heat shrinkage, it is desirable that the crystallites in the silver powder be as large as possible so that the crystallites are not sintered as much as possible.
また、近年、回路の高周波特性の向上や焼成前後における基板の寸法精度をより向上させることが求められており、このため銀厚膜が形成される基板として、上記のような通常のセラミック基板に代えてＬＴＣＣ（Ｌｏｗ Ｔｅｍｐｅｒａｔｕｒｅ Ｃｏ−ｆｉｒｅｄ Ｃｅｒａｍｉｃ：低温同時焼成セラミック）基板が用いられるようになってきている。さらに、該ＬＴＣＣ基板は、ＬＴＣＣ基板のグリーンシート（生板）と銀粉等の低抵抗導体を含む導電性ペーストとを同時に焼結させて得られるため、上記の通常のセラミック基板を用いこれに導電性ペーストを印刷して銀厚膜の回路を形成する技術に比べて、焼成回数が少なくて済み、セラミック誘電体膜厚のコントロールが容易になり、導電性ペーストから形成した回路の導体抵抗が低くなり、基板の表面平滑性が向上し易いものとなりこれらの点で好ましい。しかし、ＬＴＣＣは寸法安定性が非常に優れるため、これに用いる導電性ペーストの材料である銀粉にも熱収縮のより少ないことが強く要求され、従って銀粉中の結晶子の大きいことがより強く望まれている。 In recent years, it has been demanded to improve the high-frequency characteristics of the circuit and to further improve the dimensional accuracy of the substrate before and after firing. Therefore, as a substrate on which a thick silver film is formed, the above-mentioned ordinary ceramic substrate is used. Instead, LTCC (Low Temperature Co-fired Ceramic) substrates have come to be used. Furthermore, the LTCC substrate is obtained by simultaneously sintering a green sheet (raw plate) of the LTCC substrate and a conductive paste containing a low-resistance conductor such as silver powder. Compared to the technology of printing a conductive paste to form a thick silver film circuit, the number of firings can be reduced, the ceramic dielectric film thickness can be easily controlled, and the conductive resistance of the circuit formed from the conductive paste is low. Thus, the surface smoothness of the substrate is easily improved, which is preferable in these respects. However, since LTCC has excellent dimensional stability, silver powder, which is a material of the conductive paste used for this, is strongly required to have less heat shrinkage. Therefore, it is strongly desired that the crystallites in the silver powder are large. It is rare.
また、このように銀粉中の結晶子が大きいと、一般的に銀粉の不純物の含有量が低下し、これにより銀厚膜から形成される回路の比抵抗が低くなり易いため、上記のような焼成して形成する回路のみならず非焼成で形成する回路にも銀粉を含む導電性ペーストを用いることが可能になるという点でも好ましいものとなる。 In addition, when the crystallites in the silver powder are large in this way, the content of impurities in the silver powder is generally lowered, and thereby the specific resistance of the circuit formed from the silver thick film tends to be low. This is also preferable in that a conductive paste containing silver powder can be used not only for a circuit formed by baking but also for a circuit formed by non-firing.
上記のように、導電性ペーストに用いられる銀粉には、微粒で、分散性がよく、粒度分布がシャープすぎず比較的ブロードであり、結晶子が大きいことが望まれている。 As described above, it is desired that the silver powder used in the conductive paste is fine, has good dispersibility, is not too sharp in particle size distribution, is relatively broad, and has a large crystallite.
これに対し、特許文献１（特開２０００−１７０６号公報）には、硝酸銀水溶液とアクリル酸モノマーをＬアスコルビン酸水溶液に溶解した液とを、混合と同時に反応せしめる高結晶体銀粒子の製造方法が開示されており、該方法によれば、結晶子サイズが４００Å以上で、粒径の範囲が２〜４μｍの狭い範囲にある高結晶性銀粉が得られる。 On the other hand, Patent Document 1 (Japanese Patent Laid-Open No. 2000-1706) discloses a method for producing highly crystalline silver particles in which a silver nitrate aqueous solution and a solution obtained by dissolving an acrylic acid monomer in an L ascorbic acid aqueous solution are reacted simultaneously with mixing. According to this method, a highly crystalline silver powder having a crystallite size of 400 mm or more and a particle size range of 2 to 4 μm is obtained.
しかしながら、特許文献１記載の銀粉は、微粒で結晶子も大きいが、例えば７００℃程度の高温における熱収縮率が十分に小さくなり難い。この銀粉は、結晶子が十分に大きいにもかかわらず高温における熱収縮率が大きいが、この理由としては、該銀粉の粒径の範囲が２〜４μｍであり粒度分布がシャープすぎるため銀粉同士に空隙が形成されることにより銀粉の充填性が低くなってしまっていることに起因するものと推測される。このため、導電性ペーストにして銀厚膜の形成やＬＴＣＣ基板を用いた回路の形成に用いると、回路の形成前後における寸法変化が大きくなり、通常のセラミック基板やＬＴＣＣ基板、特にＬＴＣＣ基板において反りが生じ易いという問題があった。 However, although the silver powder described in Patent Document 1 is fine and has a large crystallite, the thermal shrinkage rate at a high temperature of, for example, about 700 ° C. is hardly reduced sufficiently. This silver powder has a large thermal shrinkage rate at high temperatures despite the sufficiently large crystallites. This is because the silver powder has a particle size range of 2 to 4 μm and the particle size distribution is too sharp. It is presumed that this is due to the low filling of silver powder due to the formation of voids. For this reason, when the conductive paste is used for forming a thick silver film or a circuit using an LTCC substrate, the dimensional change before and after the formation of the circuit increases, and warpage occurs in a normal ceramic substrate or LTCC substrate, particularly an LTCC substrate. There was a problem that it was easy to occur.
従って、本発明の目的は、微粒で、分散性がよく、粒度分布がシャープすぎず比較的ブロードであり、結晶子が大きい高結晶性銀粉、及びその製造方法を提供することにある。 Accordingly, an object of the present invention is to provide a highly crystalline silver powder that is fine, has good dispersibility, is not too sharp in particle size distribution, is relatively broad, and has a large crystallite, and a method for producing the same.
かかる実情において、本発明者は鋭意検討を行った結果、硝酸銀、分散剤及び硝酸を含む第１水溶液と、アスコルビン酸を含む第２水溶液とを混合する方法により銀粉を製造すれば、微粒で、粒度分布がシャープすぎず比較的ブロードであり、結晶子が大きく、導電性ペーストから得られる銀厚膜を耐熱収縮性に優れたものとすることができる高結晶性銀粉が得られることを見出し、本発明を完成するに至った。 In such a situation, as a result of intensive studies, the inventor made fine particles by producing silver powder by a method of mixing a first aqueous solution containing silver nitrate, a dispersant and nitric acid, and a second aqueous solution containing ascorbic acid, The particle size distribution is not too sharp and relatively broad, the crystallites are large, and it has been found that a highly crystalline silver powder can be obtained that can make the silver thick film obtained from the conductive paste excellent in heat shrinkage, The present invention has been completed.
高結晶性銀粉： 本発明に係る高結晶性銀粉は、結晶子径が３００Å以上、平均粒径ＤHigh crystalline silver powder: The high crystalline silver powder according to the present invention has a crystallite diameter of 300 mm or more and an average particle diameter D. ５０50 が０．５μｍ〜１０μｍ、Ｄ0.5 μm to 10 μm, D ９０90 ／Ｄ/ D １０10 が２．１〜５．０、且つ７００℃における長さ方向の熱収縮率が±３％以内であることを特徴とする。ただし、前記式において、Ｄ2.1 to 5.0, and the heat shrinkage rate in the length direction at 700 ° C. is within ± 3%. However, in the above formula, D １０10 及びＤAnd D ９０90 は、それぞれ、レーザー回折散乱式粒度分布測定法による累積分布１０容量％及び９０容量％におけるメジアン径（μｍ）を示している。Respectively show the median diameter (μm) at a cumulative distribution of 10% by volume and 90% by volume by a laser diffraction / scattering particle size distribution measurement method.
高結晶性銀粉の製造方法： 本発明に係る高結晶性銀粉の製造方法は、上述の高結晶性銀粉の製造方法であって、ポリビニルピロリドン又はゼラチンである分散剤、硝酸銀及び硝酸を含む第１水溶液と、アスコルビン酸を含む第２水溶液とを混合することを特徴とする。 Method for producing highly crystalline silver powder: The method for producing highly crystalline silver powder according to the present invention is a method for producing the above highly crystalline silver powder, which is a first method comprising a dispersant that is polyvinylpyrrolidone or gelatin, silver nitrate and nitric acid. An aqueous solution and a second aqueous solution containing ascorbic acid are mixed .
本発明に係る高結晶性銀粉の製造方法において、分散剤としてポリビニルピロリドンを用いる場合の前記第１水溶液は、硝酸銀１００重量部に対して、ポリビニルピロリドンが５重量部〜６０重量部、硝酸が３５重量部〜７０重量部配合することが好ましい。 In the method for producing highly crystalline silver powder according to the present invention, the first aqueous solution in the case of using polyvinylpyrrolidone as a dispersant is 5 to 60 parts by weight of polyvinylpyrrolidone and 35 parts of nitric acid with respect to 100 parts by weight of silver nitrate. It is preferable to blend by weight part to 70 parts by weight .
本発明に係る高結晶性銀粉の製造方法において、分散剤としてゼラチンを用いる場合の前記第１水溶液は、硝酸銀１００重量部に対して、ゼラチンが０．５重量部〜１０重量部、硝酸が３５重量部〜７０重量部配合することが好ましい。 In the method for producing highly crystalline silver powder according to the present invention, when gelatin is used as a dispersant, the first aqueous solution has 0.5 to 10 parts by weight of gelatin and 35 parts of nitric acid with respect to 100 parts by weight of silver nitrate. It is preferable to blend by weight part to 70 parts by weight .
本発明に係る高結晶性銀粉の製造方法において、前記第１水溶液と前記第２水溶液とを、前記第１水溶液に配合された硝酸銀１００重量部に対して、第２水溶液中に配合されたアスコルビン酸が３０重量部〜９０重量部になる比率で混合することが好ましい。 In the method for producing a highly crystalline silver powder according to the present invention, the first aqueous solution and the second aqueous solution are mixed with ascorbine in the second aqueous solution with respect to 100 parts by weight of silver nitrate mixed in the first aqueous solution. It is preferable that the acid is mixed at a ratio of 30 to 90 parts by weight .
本発明に係る高結晶性銀粉の製造方法において、前記第１水溶液と前記第２水溶液とを、前記第２水溶液に配合されたアスコルビン酸１００重量部に対して、第１水溶液中に配合された硝酸が４０重量部〜１５０重量部になる比率で混合することが好ましい。 In the method for producing highly crystalline silver powder according to the present invention, the first aqueous solution and the second aqueous solution are blended in the first aqueous solution with respect to 100 parts by weight of ascorbic acid blended in the second aqueous solution. Nitric acid is preferably mixed at a ratio of 40 to 150 parts by weight.
本発明に係る高結晶性銀粉は、微粒で、分散性がよく、粒度分布がシャープすぎず比較的ブロードであり、結晶子が大きいため、導電性ペーストの原料として用いた場合に、ペーストへの銀粉の分散性及び導電性ペーストにおける銀粉の充填性に優れ、銀厚膜から形成される電極や回路等をよりファイン化することができ、導電性ペーストから得られる銀厚膜を耐熱収縮性に優れると共に比抵抗の低いものとすることができる。また、本発明に係る高結晶性銀粉の製造方法は、上記本発明に係る高結晶性銀粉を効率的に製造することができる。 The highly crystalline silver powder according to the present invention is fine, has good dispersibility, is not too sharp in particle size distribution, is relatively broad, and has a large crystallite, so when used as a raw material for conductive paste, Excellent dispersibility of silver powder and filling ability of silver powder in conductive paste, finer electrodes and circuits formed from thick silver film, and heat resistant shrinkage of thick silver film obtained from conductive paste It can be excellent and have a low specific resistance. Moreover, the manufacturing method of the highly crystalline silver powder which concerns on this invention can manufacture the highly crystalline silver powder which concerns on the said invention efficiently.
（本発明に係る高結晶性銀粉）
本発明に係る高結晶性銀粉は、実質的に粒状の粉体である。本発明に係る高結晶性銀粉は、平均粒径Ｄ５０が０．５μｍ〜１０μｍ、好ましくは１μｍ〜５μｍである。平均粒径Ｄ５０が該範囲内にあると、導電性ペーストに用いた場合に導電性ペーストにおける銀粉の充填性に優れると共に銀厚膜から形成される回路等をよりファイン化することができるため好ましい。一方、平均粒径Ｄ５０が０．５μｍ未満であると、銀粉の回収が困難になるため好ましくなく、１０μｍを超えると、銀粉同士が凝集していることが多いため、好ましくない。ここで、平均粒径Ｄ５０とは、レーザー回折散乱法で求められる体積平均粒径、すなわち累積分布５０％における粒径をいう。
(Highly crystalline silver powder according to the present invention)
The highly crystalline silver powder according to the present invention is a substantially granular powder. The highly crystalline silver powder according to the present invention has an average particle diameter D50 of 0.5 μm to 10 μm, preferably 1 μm to 5 μm. Since the average particle diameter D 50 to be within the range, it is possible to further fine the circuit or the like formed of silver thick film excellent in filling property of the silver powder in the conductive paste when used in the conductive paste preferable. On the other hand, when the average particle diameter D 50 is less than 0.5 [mu] m, not preferable because the recovery of the silver powder becomes difficult, and when it is more than 10 [mu] m, because it is often silver powder each other are aggregated, which is not preferable. Here, the average particle diameter D 50 is the volume average particle diameter determined by a laser diffraction scattering method, namely it refers to the particle size in cumulative distribution 50%.
本発明に係る高結晶性銀粉は、結晶子径が３００Å以上、好ましくは３５０Å〜６００Åである。結晶子径が該範囲内にあると、該銀粉を含む導電性ペーストをセラミック基板に塗布し、焼成して銀厚膜からなる回路等を形成した場合に、焼成前後の銀厚膜の熱収縮率がセラミック基板の熱収縮率と近くなり、銀厚膜がセラミック基板から剥離したりセラミック基板が銀厚膜の寸法変化につられて変形したりすることを抑制する効果が大きいため好ましい。 The highly crystalline silver powder according to the present invention has a crystallite diameter of 300 mm or more, preferably 350 to 600 mm. When the crystallite diameter is within this range, when the conductive paste containing the silver powder is applied to a ceramic substrate and baked to form a circuit made of a silver thick film, the heat shrinkage of the silver thick film before and after baking The rate is close to the thermal shrinkage rate of the ceramic substrate, which is preferable because it has a large effect of suppressing the silver thick film from peeling from the ceramic substrate and the ceramic substrate from being deformed by the dimensional change of the silver thick film.
一方、結晶子径が３００Å未満であると、該銀粉を含む導電性ペーストをセラミック基板に塗布し、焼成して銀厚膜からなる回路等を形成した場合に、焼成前後の銀厚膜の収縮がセラミック基板の収縮よりも大きくなって、銀厚膜がセラミック基板から剥離したりセラミック基板が銀厚膜の寸法変化につられて変形したりし易いため好ましくない。ここで、結晶子径とは、銀粉試料に対しＸ線回折を行って得られる、各結晶面の回折角のピークの半値幅から求められる結晶子径の平均値をいう。 On the other hand, when the crystallite diameter is less than 300 mm, when the conductive paste containing the silver powder is applied to the ceramic substrate and baked to form a circuit made of a silver thick film, the silver thick film shrinks before and after baking. Is larger than the shrinkage of the ceramic substrate, and it is not preferable because the silver thick film is easily peeled off from the ceramic substrate or the ceramic substrate is easily deformed by the dimensional change of the silver thick film. Here, the crystallite diameter refers to an average value of crystallite diameters obtained from X-ray diffraction of a silver powder sample and obtained from the half width of the diffraction angle peak of each crystal plane.
本発明に係る高結晶性銀粉は、Ｄ９０／Ｄ１０が通常２．１〜５．０、好ましくは２．５〜４．７である。なお、本発明において、Ｄ１０及びＤ９０は、それぞれ、レーザー回折散乱式粒度分布測定法による累積分布１０容量％及び９０容量％におけるメジアン径（μｍ）を示す。Ｄ９０／Ｄ１０はバラツキを示す指標であり、Ｄ９０／Ｄ１０が大きいと粒度分布のバラツキが大きいことを示す。Ｄ９０／Ｄ１０が上記範囲内にあると、銀粉の粒度分布がシャープすぎず比較的ブロードになり、該銀粉を用いた導電性ペーストで回路を形成すると銀粉の充填性が優れるため回路の耐熱収縮性が優れたもの、すなわち、焼成前後における回路の寸法変化が小さいものとなり易いため好ましい。 In the highly crystalline silver powder according to the present invention, D 90 / D 10 is usually 2.1 to 5.0, preferably 2.5 to 4.7. In the present invention, D 10 and D 90 represent median diameters (μm) in cumulative distributions of 10% by volume and 90% by volume, respectively, by a laser diffraction / scattering particle size distribution measurement method. D 90 / D 10 is an index indicating variation. When D 90 / D 10 is large, it indicates that variation in particle size distribution is large. When D 90 / D 10 is within the above range, the particle size distribution of the silver powder is not too sharp and becomes relatively broad, and when a circuit is formed from a conductive paste using the silver powder, the silver powder has excellent filling properties, so the heat resistance of the circuit It is preferable because it has excellent shrinkability, that is, it tends to be small in dimensional change of the circuit before and after firing.
一方、Ｄ９０／Ｄ１０が２．１未満であると、銀粉の粒度分布がシャープになりすぎて、該銀粉を用いた導電性ペーストで回路を形成すると銀粉の充填性が劣るため回路の耐熱収縮性が悪化したもの、すなわち、焼成前後における回路の寸法変化が大きいものとなり易いため好ましくない。また、Ｄ９０／Ｄ１０が５．０を超えると、銀粉の粒度分布がブロードになりすぎて、該銀粉を用いた導電性ペーストで回路を形成すると銀粉の充填性が劣るため回路の耐熱収縮性が悪化したもの、すなわち、焼成前後における回路の寸法変化が大きいものとなり易いため好ましくない。 On the other hand, if D 90 / D 10 is less than 2.1, the particle size distribution of the silver powder becomes too sharp, and if a circuit is formed with a conductive paste using the silver powder, the filling ability of the silver powder is inferior, so the heat resistance of the circuit This is not preferable because shrinkage is deteriorated, that is, the dimensional change of the circuit before and after firing is likely to be large. On the other hand, if D 90 / D 10 exceeds 5.0, the particle size distribution of the silver powder becomes too broad, and when a circuit is formed with a conductive paste using the silver powder, the heat shrinkage of the circuit is inferior due to poor filling of the silver powder. This is not preferable because the dimensional change of the circuit before and after firing is likely to be large.
本発明に係る高結晶性銀粉は、７００℃における長さ方向の熱収縮率が、通常±３％以内、好ましくは±２％以内である。なお、本発明において±Ｘ％以内とは、−Ｘ％〜＋Ｘ％であることを意味する。本発明において、７００℃における長さ方向の熱収縮率とは、銀粉をペレットに形成した試料について、熱機械的分析（ＴＭＡ）を用いて測定したペレットの長さ方向の熱収縮率をいう。 The highly crystalline silver powder according to the present invention has a heat shrinkage rate in the length direction at 700 ° C. of usually within ± 3%, preferably within ± 2%. In the present invention, “within ± X%” means −X% to + X%. In the present invention, the heat shrinkage rate in the length direction at 700 ° C. refers to the heat shrinkage rate in the length direction of the pellets measured using thermomechanical analysis (TMA) for a sample in which silver powder is formed into pellets.
本発明に係る高結晶性銀粉は、比較的低温、例えば３００℃で焼成した銀塗膜の抵抗率が低い。すなわち、高結晶性銀粉を低温で焼結させても焼結物の抵抗率が小さくなり易い。なお、このように３００℃で焼成した銀塗膜の抵抗率が低い理由は、結晶子径が大きいことにより銀粉内の電子の動きがスムーズになるためであると推測される。 The highly crystalline silver powder according to the present invention has a low resistivity of a silver coating film fired at a relatively low temperature, for example, 300 ° C. That is, even when highly crystalline silver powder is sintered at a low temperature, the resistivity of the sintered product tends to be small. The reason why the resistivity of the silver coating film fired at 300 ° C. is low is presumed to be because the movement of electrons in the silver powder becomes smooth due to the large crystallite diameter.
本発明に係る高結晶性銀粉は、比表面積が通常０．１０ｍ２／ｇ〜１．０ｍ２／ｇ、好ましくは０．２０ｍ２／ｇ〜０．９０ｍ２／ｇである。該比表面積が０．１０ｍ２／ｇ未満であると、銀厚膜による電極や回路のファイン化が困難になり易いため好ましくない。また、該比表面積が１．０ｍ２／ｇを超えると、銀粉のペースト化が困難になり易いため好ましくない。本発明において比表面積とは、ＢＥＴ比表面積をいう。 Highly crystalline silver powder according to the present invention has a specific surface area of usually 0.10m 2 /g~1.0m 2 / g, preferably from 0.20m 2 /g~0.90m 2 / g. When the specific surface area is less than 0.10 m 2 / g, it is not preferable because it is difficult to refine the electrodes and circuits using a thick silver film. Moreover, when this specific surface area exceeds 1.0 m < 2 > / g, since it will become difficult to make silver powder into paste, it is unpreferable. In the present invention, the specific surface area means a BET specific surface area.
本発明に係る高結晶性銀粉は、タップ密度が通常３．８ｇ／ｃｍ３以上、好ましくは４．０〜６．０ｇ／ｃｍ３である。タップ密度が該範囲内にあると、導電性ペーストの作製の際に高結晶性銀粉のペーストへの銀粉の充填性が良好で導電性ペーストの作製が容易であり、また導電性ペーストの塗膜形成の際に高結晶性銀粉間に適度な空隙が形成されることにより塗膜を焼成する際に塗膜からの脱バイが容易に行われて焼成膜密度が向上し、この結果銀厚膜の抵抗を低くし易いため好ましい。本発明に係る高結晶性銀粉は、例えば、下記の方法により製造することができる。 The highly crystalline silver powder according to the present invention has a tap density of usually 3.8 g / cm 3 or more, preferably 4.0 to 6.0 g / cm 3 . When the tap density is within the above range, the conductive paste can be easily prepared because the filling property of the silver powder into the paste of the high crystalline silver powder is good and the conductive paste is easily prepared. By forming appropriate voids between the highly crystalline silver powders during the formation, debaking from the coating film is easily performed when the coating film is baked, and the sintered film density is improved. This is preferable because it is easy to reduce the resistance. The highly crystalline silver powder according to the present invention can be produced, for example, by the following method.
（本発明に係る高結晶性銀粉の製造方法）
本発明に係る高結晶性銀粉の製造方法は、硝酸銀、分散剤及び硝酸を含む第１水溶液と、アスコルビン酸を含む第２水溶液とを混合するものである。
(Method for producing highly crystalline silver powder according to the present invention)
The method for producing highly crystalline silver powder according to the present invention comprises mixing a first aqueous solution containing silver nitrate, a dispersant and nitric acid with a second aqueous solution containing ascorbic acid.
本発明において第１水溶液とは、硝酸銀、分散剤及び硝酸を含む水溶液をいう。第１水溶液の調製に用いられる水としては、純水、イオン交換水、超純水等が、銀粉への不純物の混入防止のため好ましい。本発明で用いられる硝酸銀としては、特に限定されず、固形のもの及び水溶液にしたもののいずれも用いることができる。 In the present invention, the first aqueous solution refers to an aqueous solution containing silver nitrate, a dispersant and nitric acid. As water used for the preparation of the first aqueous solution, pure water, ion-exchanged water, ultrapure water or the like is preferable for preventing contamination of silver powder with impurities. The silver nitrate used in the present invention is not particularly limited, and both solid and aqueous solutions can be used.
本発明で用いられる分散剤としては、ポリビニルピロリドン（ＰＶＰ）又はゼラチンを用いる。なお、本発明においてゼラチンとはニカワを含む概念で用いる。本発明においては、第１水溶液に分散剤を配合することにより、銀粉の分散性を向上させると共に、銀粉が微粒でその粒度分布をシャープすぎず比較的ブロードにする作用がある。この他の分散剤として、例えば、ポリエチレングリコール、ポリビニルアルコール等が挙げられる。しかし、本発明で用いられる分散剤は、ポリビニルピロリドン、ゼラチンを用いると銀粉の耐熱収縮性を特に高くすることができる。 As the dispersant used in the present invention, polyvinylpyrrolidone (PVP) or gelatin is used. In the present invention, gelatin is used as a concept including glue. In the present invention, by adding a dispersant to the first aqueous solution, the dispersibility of the silver powder is improved, and the silver powder is fine and has a function of making the particle size distribution relatively broad without being too sharp. Examples of other dispersants include polyethylene glycol and polyvinyl alcohol. However, when the dispersant used in the present invention is polyvinyl pyrrolidone or gelatin, the heat shrinkage resistance of silver powder can be particularly enhanced.
本発明で用いられる硝酸としては、特に限定されず、濃硝酸、希硝酸のいずれも用いることができる。本発明においては、第１水溶液に硝酸を配合することにより、銀イオンから銀を生成する反応速度が比較的遅くなるように制御されるため、銀粉の粒度分布をシャープすぎず比較的ブロードにし、且つ結晶子を大きくする作用がある。なお、硝酸を配合せずに銀粉を製造すると、銀イオンから銀を生成する反応速度が速すぎて反応が直ちに生じるため、本発明のように硝酸を配合して製造する場合に比べて、得られる銀粉は、粒径が小さく、且つ、結晶子径が小さくなり易い。 The nitric acid used in the present invention is not particularly limited, and either concentrated nitric acid or dilute nitric acid can be used. In the present invention, by adding nitric acid to the first aqueous solution, the reaction rate for producing silver from silver ions is controlled to be relatively slow, so that the particle size distribution of the silver powder is relatively broad without being too sharp, In addition, it has the effect of enlarging the crystallite. In addition, when silver powder is produced without blending nitric acid, the reaction rate is too high to produce silver from silver ions, and the reaction occurs immediately. Therefore, compared with the case of producing nitric acid as in the present invention, it is obtained. The silver powder obtained has a small particle size and a small crystallite diameter.
第１水溶液は、分散剤がポリビニルピロリドンである場合、硝酸銀１００重量部に対して、ポリビニルピロリドンを通常５重量部〜６０重量部、好ましくは１５重量部〜５０重量部、さらに好ましくは２０重量部〜４０重量部含む。ポリビニルピロリドンの配合量が該範囲内にあると、銀粉の分散性を向上させると共に、銀粉の粒度分布がシャープすぎず比較的ブロードになり易いため好ましい。一方、ポリビニルピロリドンの配合量が５重量部未満であると得られる銀粉が凝集し易いため好ましくなく、６０重量部を超えると得られる銀粉中の不純物濃度が高くなり易く、環境を汚染し易く、生産コストが高くなり易いため好ましくない。 When the dispersant is polyvinyl pyrrolidone, the first aqueous solution is usually 5 to 60 parts by weight, preferably 15 to 50 parts by weight, more preferably 20 parts by weight with respect to 100 parts by weight of silver nitrate. Contains 40 parts by weight. When the blending amount of polyvinyl pyrrolidone is within the above range, the dispersibility of the silver powder is improved, and the particle size distribution of the silver powder is not too sharp and relatively broad, which is preferable. On the other hand, the amount of polyvinylpyrrolidone is less than 5 parts by weight because the resulting silver powder tends to agglomerate, and when it exceeds 60 parts by weight, the impurity concentration in the obtained silver powder tends to be high, easily contaminating the environment, This is not preferable because the production cost tends to be high.
第１水溶液は、分散剤がゼラチンである場合、硝酸銀１００重量部に対して、ゼラチンを通常０．５重量部〜１０重量部、好ましくは１重量部〜８重量部、さらに好ましくは２重量部〜６重量部含む。ゼラチンの配合量が該範囲内にあると、銀粉の分散性を向上させると共に、銀粉の粒度分布がシャープすぎず比較的ブロードになり易いため好ましい。一方、ゼラチンの配合量が０．５重量部未満であると得られる銀粉が凝集し易いため好ましくなく、１０重量部を超えると得られる銀粉中の不純物濃度が高くなり易く、環境を汚染し易く、生産コストが高くなり易いため好ましくない。 When the dispersing agent is gelatin, the first aqueous solution is usually 0.5 parts by weight to 10 parts by weight, preferably 1 part by weight to 8 parts by weight, more preferably 2 parts by weight with respect to 100 parts by weight of silver nitrate. Contains 6 parts by weight. When the amount of gelatin is within this range, the dispersibility of the silver powder is improved and the particle size distribution of the silver powder is not too sharp and is relatively easy to be broadened. On the other hand, if the amount of gelatin is less than 0.5 parts by weight, the resulting silver powder tends to aggregate, which is not preferred. If it exceeds 10 parts by weight, the impurity concentration in the resulting silver powder tends to be high and the environment is easily contaminated. This is not preferable because the production cost tends to be high.
第１水溶液は、分散剤がポリビニルピロリドンである場合、水１００重量部に対しポリビニルピロリドンを、通常１重量部〜１０重量部、好ましくは２重量部〜４重量部含む。ポリビニルピロリドンの配合量が該範囲内にあると、銀粉の分散性を向上させると共に、銀粉の粒度分布がシャープすぎず比較的ブロードになり易いため好ましい。一方、ポリビニルピロリドンの配合量が１重量部未満であると得られる銀粉が凝集し易いため好ましくなく、１０重量部を超えると得られる銀粉中の不純物濃度が高くなり易く、環境を汚染し易く、生産コストが高くなり易いため好ましくない。 When the dispersing agent is polyvinyl pyrrolidone, the first aqueous solution usually contains 1 to 10 parts by weight, preferably 2 to 4 parts by weight of polyvinyl pyrrolidone with respect to 100 parts by weight of water. When the blending amount of polyvinyl pyrrolidone is within the above range, the dispersibility of the silver powder is improved, and the particle size distribution of the silver powder is not too sharp and relatively broad, which is preferable. On the other hand, the amount of polyvinylpyrrolidone is less than 1 part by weight because the resulting silver powder tends to agglomerate, and when it exceeds 10 parts by weight, the impurity concentration in the resulting silver powder tends to be high, easily contaminating the environment, This is not preferable because the production cost tends to be high.
第１水溶液は、分散剤がゼラチンである場合、水１００重量部に対しゼラチンを、通常０．１重量部〜５重量部、好ましくは０．４重量部〜２重量部含む。ゼラチンの配合量が該範囲内にあると、銀粉の分散性を向上させると共に、銀粉の粒度分布がシャープすぎず比較的ブロードになり易いため好ましい。一方、ゼラチンの配合量が０．１重量部未満であると得られる銀粉が凝集し易いため好ましくなく、５重量部を超えると得られる銀粉中の不純物濃度が高くなり易く、環境を汚染し易く、生産コストが高くなり易いため好ましくない。 When the dispersing agent is gelatin, the first aqueous solution usually contains 0.1 to 5 parts by weight, preferably 0.4 to 2 parts by weight of gelatin with respect to 100 parts by weight of water. When the amount of gelatin is within this range, the dispersibility of the silver powder is improved and the particle size distribution of the silver powder is not too sharp and is relatively easy to be broadened. On the other hand, if the amount of gelatin is less than 0.1 parts by weight, the resulting silver powder tends to aggregate, which is not preferred. If it exceeds 5 parts by weight, the impurity concentration in the resulting silver powder tends to be high and the environment is easily contaminated. This is not preferable because the production cost tends to be high.
第１水溶液は、硝酸銀１００重量部に対して、硝酸を、通常３５重量部〜７０重量部、好ましくは４０重量部〜６０重量部、さらに好ましくは４８重量部〜５４重量部含む。硝酸の配合量が該範囲内にあると、銀粉の粒度分布がシャープすぎず比較的ブロードになり、且つ結晶子を大きくする効果が大きいため好ましい。一方、硝酸の配合量が３５重量部未満であると銀粉の結晶性が低くなり易いため好ましくなく、７０重量部を超えると得られる銀粉が凝集し易いため好ましくない。なお、本発明において硝酸の配合量とは、濃度６１％の濃硝酸に換算した配合量を意味する。 1st aqueous solution contains 35 to 70 weight part nitric acid normally with respect to 100 weight part of silver nitrate, Preferably it is 40 to 60 weight part, More preferably, 48 to 54 weight part is contained. It is preferable that the amount of nitric acid is within this range because the particle size distribution of the silver powder is not too sharp and relatively broad, and the effect of increasing the crystallite is great. On the other hand, if the blending amount of nitric acid is less than 35 parts by weight, the crystallinity of the silver powder tends to be low, which is not preferable. If it exceeds 70 parts by weight, the resulting silver powder tends to aggregate, which is not preferable. In addition, the compounding quantity of nitric acid in this invention means the compounding quantity converted into the concentrated nitric acid of 61% of density | concentration.
本発明において第２水溶液とは、アスコルビン酸を含む水溶液をいう。第２水溶液の調製に用いられる水としては、純水、イオン交換水、超純水等が、銀粉への不純物の混入防止のため好ましい。本発明で用いられるアスコルビン酸としては、Ｌ体、Ｄ体のいずれも用いることができる。 In the present invention, the second aqueous solution refers to an aqueous solution containing ascorbic acid. As water used for the preparation of the second aqueous solution, pure water, ion-exchanged water, ultrapure water, or the like is preferable for preventing impurities from being mixed into the silver powder. As the ascorbic acid used in the present invention, either L-form or D-form can be used.
本発明に係る製造方法では、上記第１水溶液と第２水溶液とを混合して、混合液中で高結晶性銀粉を析出させる。混合形態としては、例えば、第１水溶液を攪拌しておきこれに第２水溶液を添加する方法が挙げられる。この場合の第２水溶液の添加方法としては、第２水溶液の全量を第１水溶液に一括添加してもよいし、第２水溶液を少量ずつ第１水溶液に徐々に添加してもよい。なお、第１水溶液中の分散剤がポリビニルピロリドンである場合は、第２水溶液の全量を第１水溶液に一括添加する方法を採用すると微粒で粒度分布がシャープすぎず比較的ブロードである銀粉を得易いため好ましく、第１水溶液中の分散剤がゼラチンである場合は、第２水溶液を少量ずつ第１水溶液に徐々に添加する方法を採用すると銀粉の粒径の制御をし易いため好ましい。 In the production method according to the present invention, the first aqueous solution and the second aqueous solution are mixed to precipitate highly crystalline silver powder in the mixed solution. Examples of the mixed form include a method of stirring the first aqueous solution and adding the second aqueous solution thereto. As a method for adding the second aqueous solution in this case, the entire amount of the second aqueous solution may be added to the first aqueous solution at once, or the second aqueous solution may be gradually added to the first aqueous solution little by little. In addition, when the dispersing agent in 1st aqueous solution is polyvinyl pyrrolidone, when the method of adding all the 2nd aqueous solution to 1st aqueous solution collectively is employ | adopted, the silver powder which is comparatively broad without the particle size distribution being too sharp is obtained. It is preferable because it is easy, and when the dispersing agent in the first aqueous solution is gelatin, it is preferable to employ a method of gradually adding the second aqueous solution to the first aqueous solution little by little because it is easy to control the particle size of the silver powder.
第１水溶液と第２水溶液との混合においては、第１水溶液に配合された硝酸銀１００重量部に対して、第２水溶液中に配合されたアスコルビン酸が、通常３０重量部〜９０重量部、好ましくは４０重量部〜８０重量部、さらに好ましくは５０重量部〜７５重量部になる比率で混合する。硝酸銀に対するアスコルビン酸の配合量が該範囲内にあると、銀粉の収率が高くなり易いため好ましい。一方、硝酸銀１００重量部に対するアスコルビン酸の配合量が３０重量部未満であると還元が不十分で銀粉の収率が低くなり易いため好ましくなく、硝酸銀１００重量部に対するアスコルビン酸の配合量が９０重量を超えると環境を汚染し易く、生産コストが高くなり易いため好ましくない。 In mixing the first aqueous solution and the second aqueous solution, ascorbic acid compounded in the second aqueous solution is usually 30 parts by weight to 90 parts by weight, preferably 100 parts by weight of silver nitrate compounded in the first aqueous solution. Is mixed at a ratio of 40 to 80 parts by weight, more preferably 50 to 75 parts by weight. It is preferable that the amount of ascorbic acid based on silver nitrate is within this range because the yield of silver powder tends to increase. On the other hand, if the amount of ascorbic acid based on 100 parts by weight of silver nitrate is less than 30 parts by weight, the reduction is insufficient and the yield of silver powder tends to be low. Exceeding this is not preferable because the environment is easily contaminated and the production cost tends to be high.
また、第１水溶液と第２水溶液との混合においては、得られた混合液中の銀イオン濃度が、通常１０ｇ／ｌ〜８０ｇ／ｌ、好ましくは３０ｇ／ｌ〜６５ｇ／ｌになる比率で混合する。混合液中の銀イオン濃度が該範囲内にあると、銀粉の収率が高く且つ得られる銀粉が凝集し難いため好ましい。一方、銀イオン濃度が１０ｇ／ｌ未満であると銀粉の生産性が悪くなり易いため好ましくなく、銀イオン濃度が８０ｇ／ｌを超えると得られる銀粉が凝集し易いため好ましくない。 In mixing the first aqueous solution and the second aqueous solution, the silver ion concentration in the obtained mixed solution is usually 10 g / l to 80 g / l, preferably 30 g / l to 65 g / l. To do. It is preferable that the silver ion concentration in the mixed solution is within this range because the yield of silver powder is high and the obtained silver powder hardly aggregates. On the other hand, if the silver ion concentration is less than 10 g / l, the productivity of the silver powder tends to deteriorate, which is not preferable. If the silver ion concentration exceeds 80 g / l, the resulting silver powder tends to aggregate, which is not preferable.
また、第１水溶液と第２水溶液との混合においては、第２水溶液に配合されたアスコルビン酸１００重量部に対して、第１水溶液中に配合された硝酸が、通常４０重量部〜１５０重量部、好ましくは５０重量部〜１２０重量部、さらに好ましくは６５重量部〜１００重量部になる比率で混合する。アスコルビン酸に対する硝酸の配合量が該範囲内にあると、銀粉の収率が高くなり易いため好ましい。一方、アスコルビン酸１００重量部に対する硝酸の配合量が４０重量部未満であると得られる銀粉の結晶子径を十分に大きくさせることが困難であるため好ましくなく、アスコルビン酸１００重量部に対する硝酸の配合量が１５０重量部を超えると得られる銀粉が凝集し易いため好ましくない。 Moreover, in mixing with 1st aqueous solution and 2nd aqueous solution, nitric acid mix | blended in 1st aqueous solution is normally 40 weight part-150 weight part with respect to 100 weight part of ascorbic acid mix | blended with 2nd aqueous solution. , Preferably 50 to 120 parts by weight, more preferably 65 to 100 parts by weight. It is preferable that the blending amount of nitric acid with respect to ascorbic acid is within this range because the yield of silver powder tends to increase. On the other hand, since it is difficult to sufficiently increase the crystallite diameter of the silver powder obtained when the blending amount of nitric acid with respect to 100 parts by weight of ascorbic acid is less than 40 parts by weight, the blending of nitric acid with respect to 100 parts by weight of ascorbic acid is not preferable. If the amount exceeds 150 parts by weight, the resulting silver powder tends to aggregate, such being undesirable.
第１水溶液と第２水溶液との混合により、混合液中に析出した銀粉は、第１水溶液と第２水溶液との混合終了後、混合液をさらに通常３分間以上、好ましくは５分間〜１０分間混合続けることにより混合液中で銀粉を成長させると、銀粉の粒径及び粒度分布並びに分散性が、本発明に係る銀粉の特定範囲内のものとなり易いため好ましい。混合液中に得られた銀粉は、例えば、ヌッチェ等の濾過手段で濾過した後、濾滓を純水で洗浄し、乾燥すると、本発明に係る高結晶性銀粉が得られる。 The silver powder precipitated in the mixed solution by mixing the first aqueous solution and the second aqueous solution is usually 3 minutes or more, preferably 5 minutes to 10 minutes after the mixing of the first aqueous solution and the second aqueous solution. It is preferable to grow silver powder in the mixed solution by continuing mixing because the particle size and particle size distribution and dispersibility of the silver powder tend to be within the specific range of the silver powder according to the present invention. After the silver powder obtained in the mixed solution is filtered by a filtering means such as Nutsche, for example, the filter cake is washed with pure water and dried to obtain the highly crystalline silver powder according to the present invention.
上記本発明に係る高結晶性銀粉は、例えば、チップ部品、プラズマディスプレイパネル、ガラスセラミックパッケージ、セラミックフィルター等の電極や回路を形成することができる導電性ペーストの原料として使用することができ、特に、銀粉の熱収縮率が非常に小さいことを利用して、回路を形成する基板として通常のセラミック基板のみならず、ＬＴＣＣ基板用の導電性ペーストの原料として好適に使用することができる。また、本発明に係る高結晶性銀粉の製造方法は、本発明に係る高結晶性銀粉の製造に使用することができる。 The highly crystalline silver powder according to the present invention can be used as a raw material for conductive paste that can form electrodes and circuits such as chip parts, plasma display panels, glass ceramic packages, ceramic filters, etc. By utilizing the fact that the thermal contraction rate of silver powder is very small, it can be suitably used as a raw material for a conductive paste for an LTCC substrate as well as a normal ceramic substrate as a substrate for forming a circuit. Moreover, the manufacturing method of the highly crystalline silver powder which concerns on this invention can be used for manufacture of the highly crystalline silver powder which concerns on this invention.
以下に実施例を示すが、本発明はこれらに限定されて解釈されるものではない。 Examples are shown below, but the present invention is not construed as being limited thereto.
常温の純水５００ｇにＰＶＰ（Ｋ価：３０）１０ｇ、硝酸銀５０ｇ及び濃硝酸（濃度６１％）２４．６ｇを入れ、攪拌し溶解して第１水溶液を調製した（第１水溶液Ａ）。一方、常温の純水５００ｇにアスコルビン酸３５．８ｇを入れ、攪拌し溶解して第２水溶液を調製した（第２水溶液Ａ）。第１水溶液及び第２水溶液の組成を表１及び表２に示す。
次に、第１水溶液Ａを攪拌した状態にし、該第１水溶液Ａに第２水溶液Ａを一括添加し、添加終了後からさらに５分間攪拌して混合液中で粒子を成長させた。その後攪拌を止め、混合液中の粒子を沈降させた後、混合液の上澄みを捨て、混合液をヌッチェを用いて濾過し、濾滓を純水で洗浄し、乾燥して、高結晶性銀粉を得た。
得られた銀粉について、Ｄ１０、Ｄ５０、Ｄ９０、Ｄ１００、ＳＤ、結晶子径、比表面積、タップ密度、熱収縮率及び抵抗率を下記方法により測定し、Ｄ９０／Ｄ１０を算出した。結果を表３〜表６に示す。
10 g of PVP (K value: 30), 50 g of silver nitrate and 24.6 g of concentrated nitric acid (concentration 61%) were added to 500 g of pure water at room temperature, and the mixture was stirred and dissolved to prepare a first aqueous solution (first aqueous solution A). On the other hand, 35.8 g of ascorbic acid was added to 500 g of pure water at room temperature, stirred and dissolved to prepare a second aqueous solution (second aqueous solution A). Tables 1 and 2 show the compositions of the first aqueous solution and the second aqueous solution.
Next, the first aqueous solution A was stirred, and the second aqueous solution A was added to the first aqueous solution A. After the addition was completed, the mixture was further stirred for 5 minutes to grow particles in the mixed solution. Thereafter, the stirring is stopped and the particles in the mixed solution are allowed to settle. Then, the supernatant of the mixed solution is discarded, the mixed solution is filtered using a Nutsche, the filter cake is washed with pure water, and dried to obtain a highly crystalline silver powder. Got.
The obtained silver powder, calculated D 10, D 50, D 90 , D 100, SD, crystallite diameter, specific surface area, tap density, thermal shrinkage and resistivity were measured by the following method, the D 90 / D 10 did. The results are shown in Tables 3 to 6.
（Ｄ１０、Ｄ５０、Ｄ９０、Ｄ１００、ＳＤ）：日機装株式会社製マイクロトラックＨＲＡを用いて、レーザー回折散乱法で求められる累積分布が１０％、５０％、９０％及び１００％の時点における粒径を、それぞれＤ１０（μｍ）、Ｄ５０（μｍ）、Ｄ９０（μｍ）、Ｄ１００（μｍ）とし、得られた粒度分布の標準偏差をＳＤとした。
（結晶子径）：リガク株式会社製Ｘ線回折装置ＲＩＮＴ２０００ＰＣを用いて粉末Ｘ線回折を行い、得られた各結晶面の回折角のピークの半値幅から結晶子径を求めた。
（比表面積）：ユアサアイオニクス株式会社製モノソーブを用いて測定したＢＥＴ比表面積を用いた。
（タップ密度）：蔵持科学機械製作所製タップデンサーを用いて試料をタッピングすることによりタップ密度を測定した。
（熱収縮率）：銀粉を押し固めて円柱状のペレットを作製し、セイコーインスツルメンツ株式会社製ＴＭＡ／ＳＳ６３００を用い、該ペレットについて、Ａｉｒ（空気）中、昇温速度１０℃／ｍｉｎで常温から８５０℃までの範囲でＴＭＡ分析を行い、ペレットの長さ方向の熱収縮率を測定した。測定温度は３００℃、５００℃及び７００℃とした。
（抵抗率）：ターピネオール９５重量部とエチルセルロース５重量部とを混合して混合溶媒を調製し、該混合溶媒１５重量部と試料粉体８５重量部とを混合してペーストを作製し、該ペーストを３００℃で焼成して数μｍ程度の厚みを有する銀塗膜を作製した。また、焼成温度を３００℃に代えて、４００℃及び５００℃とした以外は上記と同様にして銀塗膜を作製した。
次いで、（Ｈｅｗｌｅｔｔ−Ｐａｃｋａｒｄ株式会社製、ＭＩＬＬＩＯＨＭ ＭＥＴＥＲ）を用いて、四端子法で上記銀塗膜の抵抗（Ω）を測定した後、銀塗膜の断面積と端子間の長さとから抵抗率ρ（Ω・ｍ）を求めた。
(D 10 , D 50 , D 90 , D 100 , SD): When the cumulative distribution obtained by the laser diffraction scattering method is 10%, 50%, 90%, and 100% using Microtrack HRA manufactured by Nikkiso Co., Ltd. The particle diameters in D were D 10 (μm), D 50 (μm), D 90 (μm), and D 100 (μm), respectively, and the standard deviation of the obtained particle size distribution was SD.
(Crystallite diameter): Powder X-ray diffraction was performed using Rigaku Corporation's X-ray diffractometer RINT2000PC, and the crystallite diameter was determined from the half-value width of the diffraction angle peak of each obtained crystal plane.
(Specific surface area): The BET specific surface area measured using the monosorb by Yuasa Ionics Co., Ltd. was used.
(Tap density): The tap density was measured by tapping the sample using a tap denser manufactured by Kuramotsu Kagaku Kikai Seisakusho.
(Heat Shrinkage): Silver powder is pressed and solidified to produce a cylindrical pellet. Using TMA / SS6300 manufactured by Seiko Instruments Inc., the pellet is heated from room temperature at a heating rate of 10 ° C./min in Air (air). TMA analysis was performed in the range up to 850 ° C., and the thermal shrinkage in the length direction of the pellet was measured. The measurement temperature was 300 ° C, 500 ° C and 700 ° C.
(Resistivity): 95 parts by weight of terpineol and 5 parts by weight of ethyl cellulose are mixed to prepare a mixed solvent, and 15 parts by weight of the mixed solvent and 85 parts by weight of sample powder are mixed to prepare a paste. Was baked at 300 ° C. to prepare a silver coating film having a thickness of about several μm. A silver coating film was prepared in the same manner as described above except that the firing temperature was changed to 400 ° C. and 500 ° C. instead of 300 ° C.
Next, the resistance (Ω) of the silver coating film was measured by a four-terminal method using (MILLIOHM METER manufactured by Hewlett-Packard Co., Ltd.), and then the resistivity was determined from the cross-sectional area of the silver coating film and the length between the terminals. ρ (Ω · m) was determined.
常温の純水５００ｇにＰＶＰ（Ｋ価：３０）２０ｇ、硝酸銀５０ｇ及び濃硝酸（濃度６１％）２４．６ｇを入れ、攪拌し溶解して第１水溶液を調製した（第１水溶液Ｂ）。一方、常温の純水５００ｇにアスコルビン酸３５．８ｇを入れ、攪拌し溶解して第２水溶液を調製した（第２水溶液Ａ）。第１水溶液及び第２水溶液の組成を表１及び表２に示す。
次に、第１水溶液Ｂを攪拌した状態にし、該第１水溶液Ｂに第２水溶液Ａを一括添加し、添加終了後からさらに５分間攪拌して混合液中で粒子を成長させた。その後攪拌を止め、混合液中の粒子を沈降させた後、混合液の上澄みを捨て、混合液をヌッチェを用いて濾過し、濾滓を純水で洗浄し、乾燥して、高結晶性銀粉を得た。
得られた銀粉について、実施例１と同様にして、Ｄ１０、Ｄ５０、Ｄ９０、Ｄ１００、ＳＤ、結晶子径、比表面積、タップ密度、熱収縮率及び抵抗率を下記方法により測定し、Ｄ９０／Ｄ１０を算出した。結果を表３〜表６に示す。
20 g of PVP (K value: 30), 50 g of silver nitrate and 24.6 g of concentrated nitric acid (concentration 61%) were placed in 500 g of pure water at room temperature, and the mixture was stirred and dissolved to prepare a first aqueous solution (first aqueous solution B). On the other hand, 35.8 g of ascorbic acid was added to 500 g of pure water at room temperature, stirred and dissolved to prepare a second aqueous solution (second aqueous solution A). Tables 1 and 2 show the compositions of the first aqueous solution and the second aqueous solution.
Next, the first aqueous solution B was stirred, and the second aqueous solution A was added to the first aqueous solution B. After the addition was completed, the mixture was further stirred for 5 minutes to grow particles in the mixed solution. Thereafter, the stirring is stopped and the particles in the mixed solution are allowed to settle. Then, the supernatant of the mixed solution is discarded, the mixed solution is filtered using a Nutsche, the filter cake is washed with pure water, and dried to obtain a highly crystalline silver powder. Got.
The obtained silver powder, in the same manner as in Example 1, D 10, D 50, D 90, D 100, SD, crystallite diameter, specific surface area, tap density, thermal shrinkage and resistivity were measured by the following method , it was calculated D 90 / D 10. The results are shown in Tables 3 to 6.
［比較例１］
常温の純水５００ｇにＰＶＰ（Ｋ価：３０）１０ｇ及び硝酸銀５０ｇを入れ、攪拌し溶解して第１水溶液を調製した（第１水溶液Ｃ）。一方、常温の純水５００ｇにアスコルビン酸２６ｇを入れ、攪拌し溶解して第２水溶液を調製した（第２水溶液Ｂ）。第１水溶液及び第２水溶液の組成を表１及び表２に示す。
次に、第１水溶液Ｃを攪拌した状態にし、該第１水溶液Ｃに第２水溶液Ｂを一括添加し、添加終了後からさらに５分間攪拌して混合液中で粒子を成長させた。その後攪拌を止め、混合液中の粒子を沈降させた後、混合液の上澄みを捨て、混合液をヌッチェを用いて濾過し、濾滓を純水で洗浄し、乾燥して、銀粉を得た。
得られた銀粉について、実施例１と同様にして、Ｄ１０、Ｄ５０、Ｄ９０、Ｄ１００、ＳＤ、結晶子径、比表面積、タップ密度、熱収縮率及び抵抗率を下記方法により測定し、Ｄ９０／Ｄ１０を算出した。結果を表３〜表６に示す。
[Comparative Example 1]
10 g of PVP (K value: 30) and 50 g of silver nitrate were added to 500 g of pure water at room temperature, and the mixture was stirred and dissolved to prepare a first aqueous solution (first aqueous solution C). On the other hand, 26 g of ascorbic acid was added to 500 g of pure water at room temperature, and the mixture was stirred and dissolved to prepare a second aqueous solution (second aqueous solution B). Tables 1 and 2 show the compositions of the first aqueous solution and the second aqueous solution.
Next, the first aqueous solution C was stirred, and the second aqueous solution B was added to the first aqueous solution C. After the addition was completed, the mixture was further stirred for 5 minutes to grow particles in the mixed solution. Thereafter, the stirring was stopped and the particles in the mixed solution were allowed to settle. Then, the supernatant of the mixed solution was discarded, the mixed solution was filtered using a Nutsche, the filter cake was washed with pure water, and dried to obtain silver powder. .
The obtained silver powder, in the same manner as in Example 1, D 10, D 50, D 90, D 100, SD, crystallite diameter, specific surface area, tap density, thermal shrinkage and resistivity were measured by the following method , it was calculated D 90 / D 10. The results are shown in Tables 3 to 6.
常温の純水２５０ｇにゼラチン（新田ゼラチン株式会社製）１．０ｇ、硝酸銀５０ｇ及び濃硝酸（濃度６１％）２６．４ｇを入れ、５０℃まで加熱し攪拌することによりこれらを溶解して第１水溶液を調製した（第１水溶液Ｄ）。一方、常温の純水２５０ｇにアスコルビン酸２６．４ｇを入れ、攪拌し溶解して第２水溶液を調製した（第２水溶液Ｃ）。第１水溶液及び第２水溶液の組成を表１及び表２に示す。
次に、５０℃の第１水溶液Ｄを攪拌した状態にし、該第１水溶液Ｄに常温の第２水溶液Ｃを３０分かけて徐々に添加し、添加終了後からさらに５分間攪拌して混合液中で粒子を成長させた。その後攪拌を止め、混合液中の粒子を沈降させた後、混合液の上澄みを捨て、混合液をヌッチェを用いて濾過し、濾滓を純水で洗浄し、乾燥して、高結晶性銀粉を得た。
得られた銀粉について、実施例１と同様にして、Ｄ１０、Ｄ５０、Ｄ９０、Ｄ１００、ＳＤ、結晶子径、比表面積、タップ密度、熱収縮率及び抵抗率を下記方法により測定し、Ｄ９０／Ｄ１０を算出した。結果を表３〜表６に示す。
Add 250g of gelatin (made by Nitta Gelatin Co., Ltd.), 50g of silver nitrate and 26.4g of concentrated nitric acid (concentration 61%) to 250g of pure water at room temperature. One aqueous solution was prepared (first aqueous solution D). On the other hand, 26.4 g of ascorbic acid was added to 250 g of pure water at room temperature, stirred and dissolved to prepare a second aqueous solution (second aqueous solution C). Tables 1 and 2 show the compositions of the first aqueous solution and the second aqueous solution.
Next, the first aqueous solution D at 50 ° C. is stirred, and the second aqueous solution C at room temperature is gradually added to the first aqueous solution D over 30 minutes. After the addition is completed, the mixture is stirred for another 5 minutes. The particles were grown inside. Thereafter, the stirring is stopped and the particles in the mixed solution are allowed to settle. Then, the supernatant of the mixed solution is discarded, the mixed solution is filtered using a Nutsche, the filter cake is washed with pure water, and dried to obtain a highly crystalline silver powder. Got.
The obtained silver powder, in the same manner as in Example 1, D 10, D 50, D 90, D 100, SD, crystallite diameter, specific surface area, tap density, thermal shrinkage and resistivity were measured by the following method , it was calculated D 90 / D 10. The results are shown in Tables 3 to 6.
常温の純水５００ｇにゼラチン（新田ゼラチン株式会社製）３．０ｇ、硝酸銀５０ｇ及び濃硝酸（濃度６１％）２４．６ｇを入れ、５０℃まで加熱し攪拌することによりこれらを溶解して第１水溶液を調製した（第１水溶液Ｅ）。一方、常温の純水５００ｇにアスコルビン酸２５．９ｇを入れ、攪拌し溶解して第２水溶液を調製した（第２水溶液Ｄ）。第１水溶液及び第２水溶液の組成を表１及び表２に示す。
次に、５０℃の第１水溶液Ｅを攪拌した状態にし、該第１水溶液Ｅに常温の第２水溶液Ｄを３０分かけて徐々に添加し、添加終了後からさらに５分間攪拌して混合液中で粒子を成長させた。その後攪拌を止め、混合液中の粒子を沈降させた後、混合液の上澄みを捨て、混合液をヌッチェを用いて濾過し、濾滓を純水で洗浄し、乾燥して、高結晶性銀粉を得た。 得られた銀粉について、実施例１と同様にして、Ｄ１０、Ｄ５０、Ｄ９０、Ｄ１００、ＳＤ、結晶子径、比表面積、タップ密度、熱収縮率及び抵抗率を下記方法により測定し、Ｄ９０／Ｄ１０を算出した。結果を表３〜表６に示す。
Add 500 g of gelatin (manufactured by Nitta Gelatin Co., Ltd.), 50 g of silver nitrate and 24.6 g of concentrated nitric acid (concentration 61%) to 500 g of pure water at room temperature, dissolve them by heating to 50 ° C. and stirring. One aqueous solution was prepared (first aqueous solution E). On the other hand, 25.9 g of ascorbic acid was added to 500 g of pure water at room temperature, stirred and dissolved to prepare a second aqueous solution (second aqueous solution D). Tables 1 and 2 show the compositions of the first aqueous solution and the second aqueous solution.
Next, the first aqueous solution E at 50 ° C. is stirred, the second aqueous solution D at room temperature is gradually added to the first aqueous solution E over 30 minutes, and the mixture is stirred for another 5 minutes after the addition is completed. The particles were grown inside. Thereafter, the stirring is stopped and the particles in the mixed solution are allowed to settle. Then, the supernatant of the mixed solution is discarded, the mixed solution is filtered using a Nutsche, the filter cake is washed with pure water, and dried to obtain a highly crystalline silver powder. Got. The obtained silver powder, in the same manner as in Example 1, D 10, D 50, D 90, D 100, SD, crystallite diameter, specific surface area, tap density, thermal shrinkage and resistivity were measured by the following method , it was calculated D 90 / D 10. The results are shown in Tables 3 to 6.
表１〜表５より、分散剤及び硝酸を用いて作製した銀粉は、結晶子径が大きくて高結晶性であり、７００℃における熱収縮率が小さいことが判る。また、分散剤としてゼラチンを用いたものは、特に７００℃における熱収縮率が小さいことが判る。また、表６より、分散剤及び硝酸を用いて作製した銀粉は、硝酸を用いずに作製した銀粉に比べて、３００℃で焼成した銀塗膜の抵抗率ρが低いことが判る。この理由は、結晶子径が大きいことにより銀粉内の電子の動きがスムーズになるためであると推測される。 From Tables 1 to 5, it can be seen that the silver powder produced using the dispersant and nitric acid has a large crystallite size and high crystallinity, and a small thermal shrinkage at 700 ° C. It can also be seen that those using gelatin as a dispersant have a small heat shrinkage rate especially at 700 ° C. Further, it can be seen from Table 6 that the silver powder produced using the dispersant and nitric acid has a lower resistivity ρ of the silver coating film fired at 300 ° C. than the silver powder produced without using nitric acid. This is presumed to be because the movement of electrons in the silver powder becomes smooth due to the large crystallite diameter.
本発明に係る高結晶性銀粉及び高結晶性銀粉の製造方法は、例えば、チップ部品、プラズマディスプレイパネル、ガラスセラミックパッケージ、セラミックフィルター等の電極や回路を形成することができる導電性ペーストの原料として使用することができ、特に、ＬＴＣＣ基板用の導電性ペーストの原料として好適に使用することができる。 The method for producing highly crystalline silver powder and highly crystalline silver powder according to the present invention is, for example, as a raw material for conductive paste capable of forming electrodes and circuits such as chip parts, plasma display panels, glass ceramic packages, and ceramic filters. In particular, it can be suitably used as a raw material for a conductive paste for an LTCC substrate.
Claims (6)
（ただし、前記式において、Ｄ１０及びＤ９０は、それぞれ、レーザー回折散乱式粒度分布測定法による累積分布１０容量％及び９０容量％におけるメジアン径（μｍ）を示す。） The crystallite diameter is 300 mm or more, the average particle diameter D 50 is 0.5 μm to 10 μm, D 90 / D 10 is 2.1 to 5.0, and the heat shrinkage in the length direction at 700 ° C. is within ± 3%. A highly crystalline silver powder characterized by being.
(In the above formula, D 10 and D 90 represent median diameters (μm) in cumulative distributions of 10% by volume and 90% by volume, respectively, by a laser diffraction scattering type particle size distribution measurement method.)
ポリビニルピロリドン又はゼラチンである分散剤、硝酸銀及び硝酸を含む第１水溶液と、アスコルビン酸を含む第２水溶液とを混合することを特徴とする高結晶性銀粉の製造方法。 A method for producing the highly crystalline silver powder according to claim 1,
A method for producing highly crystalline silver powder, comprising mixing a first aqueous solution containing a dispersant, silver nitrate and nitric acid , which is polyvinylpyrrolidone or gelatin, and a second aqueous solution containing ascorbic acid.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63307206A (en) * | 1987-06-08 | 1988-12-14 | Tanaka Kikinzoku Kogyo Kk | Production of fine silver particles |
| JPH01104338A (en) * | 1987-10-15 | 1989-04-21 | Tanaka Kikinzoku Kogyo Kk | Manufacture of silver colloid |
| JP2000001706A (en) * | 1998-06-17 | 2000-01-07 | Tanaka Kikinzoku Kogyo Kk | High crystal silver particle, its production and conductor paste consisting of high crystal silver particle |
| JP2000001707A (en) * | 1998-06-17 | 2000-01-07 | Tanaka Kikinzoku Kogyo Kk | Silver particle, its production and conductor paste consisting of silver particle |
| JP2000265225A (en) * | 1999-03-15 | 2000-09-26 | Aida Kagaku Kogyo Kk | Manufacture of noble metal high strength sintered compact, and noble metal high strength sintered compact |
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2004
- 2004-02-10 JP JP2004034121A patent/JP4976642B2/en not_active Expired - Lifetime
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2005
- 2005-02-04 KR KR1020067018248A patent/KR101215458B1/en not_active IP Right Cessation
- 2005-02-04 EP EP05709726A patent/EP1721690A1/en not_active Withdrawn
- 2005-02-04 CN CNA2005800063565A patent/CN1925941A/en active Pending
- 2005-02-04 US US10/588,970 patent/US20090023007A1/en not_active Abandoned
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Also Published As
| Publication number | Publication date |
|---|---|
| EP1721690A1 (en) | 2006-11-15 |
| JP2005226094A (en) | 2005-08-25 |
| KR20070018025A (en) | 2007-02-13 |
| TWI286090B (en) | 2007-09-01 |
| CN1925941A (en) | 2007-03-07 |
| WO2005075133A1 (en) | 2005-08-18 |
| TW200536636A (en) | 2005-11-16 |
| KR101215458B1 (en) | 2012-12-26 |
| US20090023007A1 (en) | 2009-01-22 |
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