TW201942263A - Electroconductive paste - Google Patents
Electroconductive paste Download PDFInfo
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- TW201942263A TW201942263A TW108109656A TW108109656A TW201942263A TW 201942263 A TW201942263 A TW 201942263A TW 108109656 A TW108109656 A TW 108109656A TW 108109656 A TW108109656 A TW 108109656A TW 201942263 A TW201942263 A TW 201942263A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/30—Stacked capacitors
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
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Abstract
Description
本發明是有關於一種導電性糊。更詳細而言,本發明是有關於一種對於積層陶瓷電子零件的內部電極層的形成而言較佳的導電性糊。
本申請案主張基於2018年3月30日所申請的日本專利申請2018-068733號的優先權,並將該申請的全部內容作為參照而編入至本說明書中。The present invention relates to a conductive paste. More specifically, the present invention relates to a conductive paste that is preferable for forming an internal electrode layer of a laminated ceramic electronic component.
This application claims priority based on Japanese Patent Application No. 2018-068733 filed on March 30, 2018, and incorporates the entire contents of this application into this specification by reference.
積層陶瓷電容器(Multi-Layer Ceramic Capacitor,MLCC)具有將包含陶瓷的介電質層與內部電極層多個積層而成的結構。所述MLCC通常藉由如下方式製作:於包含介電質粉末與黏合劑等的介電質生片(green sheet)上印刷含有導電性粉末的內部電極用的導電性糊,形成內部電極層,將印刷了該內部電極層的介電質生片多個積層並壓接,進行鍛燒。此處,例如專利文獻1中揭示了一種導電性糊,其含有導電性粒子、以及包含介電質粒子的共存材料,共存材料具備非導電性被覆部。根據所述構成,記載了於導電性粒子燒結而形成內部電極層時,不會使介隔存在於導電性粒子間的共存材料彼此反應,而可較佳地抑制導電性粒子的異常晶粒成長。
[現有技術文獻]
[專利文獻]A multi-layer ceramic capacitor (MLCC) has a structure in which a dielectric layer including a ceramic and a plurality of internal electrode layers are laminated. The MLCC is generally produced by printing a conductive paste for an internal electrode containing a conductive powder on a dielectric green sheet including a dielectric powder, a binder, and the like to form an internal electrode layer. A plurality of dielectric green sheets printed with the internal electrode layer were laminated and pressure-bonded, and calcined. Here, for example, Patent Document 1 discloses a conductive paste containing a conductive particle and a coexisting material containing a dielectric particle, and the coexisting material includes a non-conductive coating portion. According to the above-mentioned configuration, when the conductive particles are sintered to form the internal electrode layer, it is described that abnormal grain growth of the conductive particles can be better suppressed without reacting the coexisting materials interposed between the conductive particles. .
[Prior Art Literature]
[Patent Literature]
[專利文獻1]日本專利申請公開第2007-123198號公報[Patent Document 1] Japanese Patent Application Publication No. 2007-123198
[發明所欲解決之課題][Problems to be Solved by the Invention]
且說,伴隨著電子機器的小型、輕量化,關於構成電子機器的各電子零件亦要求小型薄層化。MLCC中,要求藉由使介電質層進一步變薄且進一步增加積層數來擴大電極面積,使MLCC的體積小型化且增大靜電電容。根據所述介電質層及內部電極層的薄層化,例如用於形成內部電極層的粉末的平均粒徑被微細化至共存材料中為10 nm水準、導電性粒子中為數100 nm水準。因此,準備專利文獻1中揭示的具備非導電性被覆部的共存材料變得極其困難。In addition, with the miniaturization and weight reduction of electronic devices, miniaturization and thickness reduction of each electronic component constituting the electronic devices is also required. In MLCC, it is required to enlarge the electrode area by further thinning the dielectric layer and further increasing the number of layers, so that the volume of the MLCC is miniaturized and the electrostatic capacitance is increased. According to the thinning of the dielectric layer and the internal electrode layer, for example, the average particle diameter of the powder used to form the internal electrode layer is refined to a level of 10 nm in the coexisting material and a level of several hundred nm in the conductive particles. Therefore, it is extremely difficult to prepare a coexisting material including a non-conductive coating portion disclosed in Patent Document 1.
另一方面,伴隨著介電質層及內部電極層的薄層化,迄今為止並未成為問題的水準下的導電性粒子的晶粒成長成為問題。例如,藉由導電性粒子於鍛燒時過剩地晶粒成長,內部電極層膨脹而介電質層受到壓迫,存在引起介電質層的耐電壓的下降、或可靠性的下降等問題。另外,若導電性粒子進一步粗大地晶粒成長,則會刺破經薄層化的介電質層,存在導致製品不良且引起良率的下降等問題。認為所述導電性粒子的晶粒成長是由於如下情況而產生:於鍛燒前的導電性糊塗膜中導電性粒子與介電質粒子不均勻地存在,導電性粒子彼此的接點較多的部位(即,不存在介電質粒子的部分)存在多個,無法發揮介電質粒子帶來的燒結抑制效果。另外,關於所述導電性粒子與介電質粒子的不均勻性,若該些粉末變得微細且表面活性提高,則可變得更顯著。On the other hand, with the thinning of the dielectric layer and the internal electrode layer, grain growth of conductive particles at a level that has not been a problem until now becomes a problem. For example, due to excessive grain growth of the conductive particles during calcination, the internal electrode layer expands and the dielectric layer is pressed, which causes problems such as a decrease in withstand voltage of the dielectric layer or a decrease in reliability. In addition, if the conductive particles grow even coarser, they will pierce the thinned dielectric layer, causing problems such as defective products and a reduction in yield. It is considered that the grain growth of the conductive particles is caused by the fact that the conductive particles and the dielectric particles exist unevenly in the conductive paste coating film before the calcination, and there are many contacts between the conductive particles. There are multiple sites (i.e., parts where no dielectric particles are present), and the sintering suppression effect by the dielectric particles cannot be exhibited. In addition, as for the non-uniformity between the conductive particles and the dielectric particles, if these powders become finer and the surface activity is improved, they can become more significant.
本發明是鑒於所述方面而成,其目的在於提供一種導電性糊,其由於導電性粉末與介電質粉末的分散穩定性良好,因此鍛燒時的異常晶粒成長等問題得到抑制。
[解決課題之手段]The present invention has been made in view of the above-mentioned aspects, and an object thereof is to provide a conductive paste which has good dispersion stability of the conductive powder and the dielectric powder, and therefore suppresses problems such as abnormal grain growth during firing.
[Means for solving problems]
根據本發明者等人的研究,即使導電性糊使用的原料相同,亦可藉由調整糊製備條件而使糊中的導電性粉末及介電質粉末的分散狀態變化。而且,發現藉由以如下述般規定的「透過率變化速度」實現0.003以下的方式,對糊製備條件進行各種控制,可獲得具備前所未有的高水準的分散穩定性的導電性糊。本技術是基於所述見解而完成。According to research by the present inventors, even if the same raw materials are used for the conductive paste, the dispersion state of the conductive powder and the dielectric powder in the paste can be changed by adjusting the preparation conditions of the paste. In addition, it has been found that by controlling the paste preparation conditions in various ways to achieve a "transmittance change rate" defined as described below, a conductive paste having an unprecedentedly high level of dispersion stability can be obtained. This technology was completed based on the said insight.
即,藉由本文揭示的技術,可提供一種導電性糊,其用於導體膜的形成,且包含:導電性粉末、介電質粉末及有機成分。此處,關於對所述導電性糊實施離心沈降處理時的所述導電性粉末及所述介電質粉末的離心沈降行為,於藉由如下透過率變化速度進行評價時,以所述透過率變化速度成為0.003以下的方式製備,所述透過率變化速度定義為基於沿所述離心沈降方向的透過率分佈而計算出的積分透過率的每單位時間的變化量。That is, by the technique disclosed herein, a conductive paste can be provided for forming a conductive film, and includes a conductive powder, a dielectric powder, and an organic component. Here, the centrifugal sedimentation behavior of the conductive powder and the dielectric powder when the centrifugal sedimentation treatment is performed on the conductive paste is evaluated by the transmittance change rate as described below. It is prepared so that the change rate becomes 0.003 or less, and the transmittance change rate is defined as a change amount per unit time of the integrated transmittance calculated based on the transmittance distribution in the centrifugal sedimentation direction.
根據所述構成,實現了一種導電性糊:導電性粉末與介電質粉末於有機成分中極其穩定地分散,且可長期維持其分散狀態。根據所述導電性糊,導電性粉末與介電質粉末以良好的分散狀態存在於有機成分中,因此於形成塗膜時亦可較佳地抑制導電性粉末彼此凝聚或接觸,可大幅度地抑制對所述塗膜進行鍛燒時的晶粒成長。藉此,可將鍛燒後的導體膜中的導電性粒子及介電質粒子的尺寸維持地小,且抑制例如導電性粒子的異常成長所引起的介電質層的刺破。結果可製成品質與可靠性優異的電子零件。According to the configuration, a conductive paste is realized in which a conductive powder and a dielectric powder are extremely stably dispersed in an organic component, and the dispersed state can be maintained for a long period of time. According to the conductive paste, the conductive powder and the dielectric powder are present in the organic component in a well-dispersed state. Therefore, when the coating film is formed, the conductive powders can also be prevented from agglomerating or contacting with each other, and can be greatly Grain growth is suppressed when the coating film is calcined. Thereby, the size of the conductive particles and the dielectric particles in the calcined conductor film can be kept small, and, for example, puncture of the dielectric layer due to abnormal growth of the conductive particles can be suppressed. As a result, electronic parts with excellent quality and reliability can be manufactured.
再者,本說明書中,所謂「透過率變化速度」是指藉由經時地獲取有關導電性糊的光透過率分佈曲線而獲得的積分光透過率(T)的每單位時間的變化量(ΔT/Δt)。光透過率分佈曲線可藉由如下方式獲得:關於對導電性糊進行離心沈降處理時的糊中所含的粒子的沈降狀態,利用光透過法或光反射法等光學檢測方法,於糊的整個區域中沿離心沈降方向實時地且直接地測定光透過率或光反射率。本文揭示的發明中,採用所述透過率變化速度作為評價導電性糊的分散穩定性的指標。所述粒子的離心沈降狀態可藉由後述的實施例中具體示出的方法正確且定量地測量。In addition, in the present specification, the "transmittance change rate" means a change amount per unit time of the integrated light transmittance (T) obtained by obtaining a light transmittance distribution curve of the conductive paste over time ( ΔT / Δt). The light transmittance distribution curve can be obtained as follows: About the sedimentation state of particles contained in the paste when the conductive paste is subjected to a centrifugal sedimentation process, an optical detection method such as a light transmission method or a light reflection method is used for the entire paste. The light transmittance or light reflectance is measured in real time and directly in the area along the centrifugal sedimentation direction. In the invention disclosed herein, the transmission rate change rate is used as an index for evaluating the dispersion stability of the conductive paste. The centrifugal sedimentation state of the particles can be accurately and quantitatively measured by the method specifically shown in the examples described later.
於本文揭示的導電性糊的較佳的一態樣中,於將所述導電性粉末的基於布厄特(Brunauer Emmett Tellern,BET)法的平均粒徑設為D1 ,將所述介電質粉末的基於BET法的平均粒徑設為D2 時,滿足0.03×D1 ≦D2 ≦0.4×D1 。藉此,即便於形成薄導電膜的情況下,介電質粒子亦可較佳地配置於導電性粒子的空隙,藉由介電質粉末較佳地抑制鍛燒時的導電性粒子的異常晶粒成長。In a preferred aspect of the conductive paste disclosed herein, the average particle diameter of the conductive powder based on the Brunauer Emmett Tellern (BET) method is set to D 1 , and the dielectric When the average particle diameter of the fine powder by the BET method is D 2 , 0.03 × D 1 ≦ D 2 ≦ 0.4 × D 1 is satisfied. Thereby, even in the case of forming a thin conductive film, the dielectric particles can be preferably arranged in the voids of the conductive particles, and the dielectric powder can better suppress the abnormal crystals of the conductive particles at the time of firing. Grain grows.
於本文揭示的導電性糊的較佳的一態樣中,所述導電性粉末的基於BET法的所述平均粒徑D1 為0.5 μm以下。藉此,例如可高精度地形成厚度約3 μm以下左右的導體膜。In a preferred aspect of the conductive paste disclosed herein, the average particle diameter D 1 of the conductive powder by the BET method is 0.5 μm or less. Thereby, for example, a conductor film having a thickness of about 3 μm or less can be formed with high accuracy.
於本文揭示的導電性糊的較佳的一態樣中,所述導電性粉末為鎳、鉑、鈀、銀及銅中的至少一種。藉此,可較佳地實現電傳導性優異的導體膜。In a preferred aspect of the conductive paste disclosed herein, the conductive powder is at least one of nickel, platinum, palladium, silver, and copper. Thereby, a conductive film excellent in electrical conductivity can be preferably realized.
於本文揭示的導電性糊的較佳的一態樣中,所述介電質粉末為選自由鈦酸鋇、鈦酸鍶及鋯酸鈣所組成的群組中的至少一種。藉此,可較佳地實現與高介電常數的介電質層的接合性優異的導體膜。In a preferred aspect of the conductive paste disclosed herein, the dielectric powder is at least one selected from the group consisting of barium titanate, strontium titanate, and calcium zirconate. Thereby, a conductive film excellent in adhesion with a dielectric layer having a high dielectric constant can be preferably realized.
於本文揭示的導電性糊的較佳的一態樣中,可用於形成積層陶瓷電子零件的內部電極層。例如關於晶片型MLCC,要求介電質層的進一步的薄層化與高積層化。所述薄(例如1 μm以下)介電質層之間配置的內部電極層藉由使用本文揭示的導電性糊,可作為表面平坦性高、電連接且均質者而較佳地形成。結果,可較佳地實現介電質層的短路、裂紋等的發生得到抑制的、小型、大容量且高品質的MLCC。In a preferred aspect of the conductive paste disclosed herein, it can be used to form an internal electrode layer of a laminated ceramic electronic component. For example, wafer-type MLCCs require further thinning and high-layering of the dielectric layer. The internal electrode layer disposed between the thin (for example, 1 μm or less) dielectric layers can be preferably formed by using the conductive paste disclosed herein as one having high surface flatness, electrical connection, and homogeneity. As a result, a small-sized, large-capacity, and high-quality MLCC with suppressed occurrence of short-circuits, cracks, and the like of the dielectric layer can be preferably realized.
以下,一面適宜參照圖式一面對本發明的較佳實施形態加以說明。再者,於本說明書中特別提及的事項(例如,導電性糊的構成或其性狀)以外的事情且為本發明的實施中所需的事情(例如,關於所述糊的原料的製備及對基材的應用的具體的方法、電子零件的構成等)可基於由本說明書所教示的技術內容及該領域中的從業人員的一般的技術常識來實施。再者,於本說明書中表示數值範圍的「A~B」這一表述是指A以上且B以下。Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as appropriate. Furthermore, matters other than those specifically mentioned in this specification (for example, the composition of a conductive paste or its properties) are matters required for the implementation of the present invention (for example, the preparation of raw materials for the paste and The specific method of applying the base material, the configuration of electronic components, etc.) can be implemented based on the technical content taught by this specification and the general technical common sense of those skilled in the art. In addition, the expression "A to B" which shows a numerical range in this specification means A or more and B or less.
[導電性糊]
本文揭示的導電性糊包含(A)導電性粉末、(B)介電質粉末及有機成分作為主要的構成成分。所謂有機成分,典型而言是被稱為包含(C)黏合劑及(D)分散介質的媒液(vehicle)的介質。而且,所述導電性糊藉由進行鍛燒,有機成分會消失,(A)導電性粉末及(B)介電質粉末經燒結而形成導電性的燒結體(典型而言為導體膜)。作為構成導體膜的主體的(A)導電性粉末與(B)介電質粉末通常藉由分散於作為有機成分的媒液中而形成糊,被賦予適度的黏性與流動性。[Conductive paste]
The conductive paste disclosed herein includes (A) a conductive powder, (B) a dielectric powder, and an organic component as main constituent components. The organic component is typically a medium called a vehicle containing (C) a binder and (D) a dispersion medium. In addition, when the conductive paste is calcined, organic components disappear, and (A) the conductive powder and (B) the dielectric powder are sintered to form a conductive sintered body (typically, a conductive film). The (A) conductive powder and (B) dielectric powder, which are the main body of the conductor film, are usually dispersed in a vehicle liquid as an organic component to form a paste, and are imparted with appropriate viscosity and fluidity.
進而,本文揭示的導電性糊以透過率變化速度成為0.003以下的方式製備。藉此,於媒液中(A)導電性粉末與(B)介電質粉末高度地分散,可長期維持高分散性。例如,即便於後述的4000 rpm的離心沈降處理被施加100分鐘的情況下,(A)導電性粉末與(B)介電質粉末的沈降得到抑制,不會引起(A)導電性粉末及(B)介電質粉末、與有機成分的完全分離。認為所述前所未有的高分散穩定性與其說是導電性糊的構成材料的單獨的性狀,倒不如說是藉由導電性糊中的各構成材料的存在狀態而實現。以下,按照各要素對本文揭示的導電性糊進行說明。Furthermore, the conductive paste disclosed herein is prepared so that the transmittance change rate becomes 0.003 or less. As a result, the conductive powder (A) and the dielectric powder (B) are highly dispersed in the medium, and high dispersibility can be maintained for a long period of time. For example, even if a centrifugal sedimentation treatment of 4000 rpm described later is applied for 100 minutes, sedimentation of (A) conductive powder and (B) dielectric powder is suppressed, and (A) conductive powder and ( B) The dielectric powder is completely separated from the organic components. The unprecedented high dispersion stability is considered to be achieved by the existence state of each constituent material in the conductive paste rather than the individual properties of the constituent materials of the conductive paste. Hereinafter, the conductive paste disclosed herein will be described according to each element.
(A)導電性粉末
導電性粉末是用以主要形成電子元件等中的電極、導線或導電膜等電傳導性(以下,簡稱為「導電性」)高的導體物(可為導體膜)的材料。因此,導電性粉末可無特別限制地使用具備所需的導電性的各種材料的粉末。作為所述導電性材料,例如具體而言例示了鎳(Ni)、鈀(Pd)、鉑(Pt)、金(Au)、銀(Ag)、銅(Cu)、釕(Ru)、銠(Rh)、鋨(Os)、銥(Ir)、鋁(Al)、鎢(W)等金屬的單體、以及含有該些金屬的合金等。導電性粉末可單獨使用任一種,亦可組合使用兩種以上。(A) Conductive powder Conductive powder is mainly used to form conductive materials (such as conductive films) with high electrical conductivity (hereinafter, referred to as "conductivity") in electrodes, wires, or conductive films in electronic components and the like. material. Therefore, as the conductive powder, powders of various materials having desired conductivity can be used without particular limitation. Specific examples of the conductive material include nickel (Ni), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), copper (Cu), ruthenium (Ru), and rhodium ( Rh), osmium (Os), iridium (Ir), aluminum (Al), tungsten (W) and other metals, and alloys containing these metals. The conductive powder may be used singly or in combination of two or more kinds.
再者,雖無特別限定,但例如關於在形成MLCC內部電極層的用途中使用的導電性糊,較佳為導電性粉末的熔點低於介電質層的燒結溫度(例如約1300℃)的金屬種的使用。作為所述金屬種的一例,可列舉銠、鉑、鈀、銅、金等貴金屬以及鎳等卑金屬。其中,就熔點及導電性的觀點而言,較佳為鉑、鈀等貴金屬的使用,但若進一步考慮到穩定且價格低的方面,則較佳為使用鎳。In addition, although it is not particularly limited, for example, regarding a conductive paste used for the purpose of forming an MLCC internal electrode layer, a conductive powder having a melting point lower than the sintering temperature of the dielectric layer (for example, about 1300 ° C) is preferred. Use of metal species. Examples of the metal species include precious metals such as rhodium, platinum, palladium, copper, and gold, and base metals such as nickel. Among them, the use of noble metals such as platinum and palladium is preferred from the viewpoint of melting point and conductivity, but nickel is more preferably used in consideration of stability and low price.
導電性粉末的製法、構成導電性粉末的粒子的尺寸或形狀等性狀並無特別限制。例如,考慮到鍛燒收縮率,可為包括於作為目標的電極的最小尺寸(典型而言電極層的厚度及/或寬度)的範圍內。例如,導電性粉末的平均粒徑可為數nm~數十μm左右、例如10 nm~10 μm左右。
再者,本說明書中,所謂關於導電性粉末及介電質粉末的「平均粒徑(DB
)」,只要無特別說明,則是指根據基於BET法所測定的比表面積S與所述粉末的比重ρ並藉由以下式:DB
=6/(S×ρ)計算出的值。關於比表面積將後述。There are no particular restrictions on properties such as the method for producing the conductive powder and the size or shape of particles constituting the conductive powder. For example, in consideration of the calcination shrinkage rate, it may be included in the range of the minimum size of the target electrode (typically, the thickness and / or width of the electrode layer). For example, the average particle diameter of the conductive powder may be about several nm to several tens of μm, for example, about 10 nm to 10 μm.
In addition, in this specification, the "average particle diameter (D B )" of a conductive powder and a dielectric powder means a specific surface area S measured by a BET method and the powder unless otherwise specified. The specific gravity ρ is calculated by the following formula: D B = 6 / (S × ρ). The specific surface area will be described later.
另外,例如於形成小型、大容量MLCC的內部電極層的用途中,重要的是導電性粉末的平均粒徑小於內部電極層的厚度(積層方向的尺寸)。換言之,較佳為實際上不含有超過內部電極層的厚度的粗大粒子。就所述觀點而言,關於導電性粉末,作為一例,較佳為累積90%粒徑(D90 )不超過3 μm,更佳為不超過1 μm、例如較佳為不超過0.5 μm。另外,關於平均粒徑(D50 ),可以大致1 μm以下為標準,可為典型而言0.5 μm以下、較佳為0.3 μm以下、更佳為0.25 μm以下、例如0.2 μm以下。若平均粒徑為規定值以下,則可穩定地形成導體膜。另外,可較佳地抑制所形成的導體膜的表面粗糙度。例如,可將算數平均粗糙度Ra抑制為5 nm以下的水準。In addition, for example, in the application for forming an internal electrode layer of a small-sized, large-capacity MLCC, it is important that the average particle diameter of the conductive powder is smaller than the thickness (size in the stacking direction) of the internal electrode layer. In other words, it is preferable not to contain coarse particles that actually exceed the thickness of the internal electrode layer. From the viewpoint, as an example, the conductive powder preferably has a cumulative 90% particle diameter (D 90 ) of not more than 3 μm, more preferably not more than 1 μm, and more preferably not more than 0.5 μm. The average particle diameter (D 50 ) may be approximately 1 μm or less as a standard, and may be typically 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.25 μm or less, such as 0.2 μm or less. When the average particle diameter is equal to or smaller than a predetermined value, a conductive film can be formed stably. In addition, the surface roughness of the formed conductor film can be preferably suppressed. For example, the arithmetic average roughness Ra can be suppressed to a level of 5 nm or less.
導電性粉末的平均粒徑的下限亦無特別限制,例如可為0.005 μm以上,可為大致0.01 μm以上、典型而言為0.05 μm以上、較佳為0.1 μm以上、例如0.12 μm以上。藉由平均粒徑不會過小,可抑制構成導電性粉末的粒子的表面能量(活性),可抑制導電性糊中的粒子的凝聚。另外,可提高糊塗佈層的密度,較佳地形成電傳導性、緻密性高的導體膜。The lower limit of the average particle diameter of the conductive powder is also not particularly limited, and may be, for example, 0.005 μm or more, approximately 0.01 μm or more, typically 0.05 μm or more, preferably 0.1 μm or more, such as 0.12 μm or more. By preventing the average particle diameter from being too small, the surface energy (activity) of the particles constituting the conductive powder can be suppressed, and the aggregation of the particles in the conductive paste can be suppressed. In addition, the density of the paste coating layer can be increased, and a conductive film having high electrical conductivity and high density can be preferably formed.
導電性粉末的比表面積並無特別限定,可為大致10 m2 /g以下、較佳為1 m2 /g~8 m2 /g、例如2 m2 /g~6 m2 /g。藉此,可較佳地抑制糊中的凝聚,可更良好地提高糊的均質性、分散性、保存穩定性。另外,可更穩定地實現電傳導性優異的導體膜。再者,比表面積是指基於藉由例如使用氮氣(N2 )氣體作為吸附質的氣體吸附法(定容量吸附法)所測定的氣體吸附量,並藉由BET法(例如BET一點法)計算出的值。The specific surface area of the conductive powder is not particularly limited, and may be approximately 10 m 2 / g or less, preferably 1 m 2 / g to 8 m 2 / g, for example, 2 m 2 / g to 6 m 2 / g. Thereby, the aggregation in the paste can be better suppressed, and the homogeneity, dispersibility, and storage stability of the paste can be better improved. In addition, a conductive film excellent in electrical conductivity can be realized more stably. The specific surface area refers to a gas adsorption amount measured by a gas adsorption method (constant volume adsorption method) using, for example, nitrogen (N 2 ) gas as an adsorbent, and is calculated by a BET method (for example, a BET one-point method). Out value.
導電性粉末的形狀並無特別限定。例如MLCC內部電極等的一部分的電極形成用途的導電性糊中的導電性粉末的形狀可為正球狀或大致球狀。導電性粉末的平均縱橫比可為典型而言1~2、較佳為1~1.5。藉此,可將糊的黏度維持地低,提高糊的操作性或用於導體膜形成的成膜時的作業性。另外,亦可提高糊的均質性。
再者,本說明書中的「縱橫比」基於電子顯微鏡觀察而計算出,是指於描繪與構成粉末的粒子外接的矩形時的長邊的長度(b)相對於短邊的長度(a)的比(b/a)。平均縱橫比是關於100個粒子而獲得的縱橫比的算數平均值。The shape of the conductive powder is not particularly limited. For example, the shape of the conductive powder in the conductive paste for a part of an electrode forming application such as an MLCC internal electrode may be a spherical shape or a substantially spherical shape. The average aspect ratio of the conductive powder may be typically 1 to 2, and preferably 1 to 1.5. Thereby, the viscosity of the paste can be maintained low, and the operability of the paste or the workability when forming a conductive film can be improved. In addition, the homogeneity of the paste can be improved.
The "aspect ratio" in this specification is calculated based on observation with an electron microscope, and refers to the length of the long side (b) relative to the length of the short side (a) when drawing a rectangle circumscribed with the particles constituting the powder. Ratio (b / a). The average aspect ratio is an arithmetic average of the aspect ratios obtained for 100 particles.
導電性粉末的含有比例並無特別限定,於將導電性糊整體設為100質量%時,可為大致30質量%以上、典型而言為40質量%~95質量%、例如45質量%~60質量%。藉由滿足所述範圍,可較佳地實現電傳導性、緻密性高的導體層。另外,亦可提高糊的操作性、成膜時的作業性。The content ratio of the conductive powder is not particularly limited. When the entire conductive paste is 100% by mass, it may be approximately 30% by mass or more, typically 40% to 95% by mass, for example, 45% to 60% by mass. quality%. By satisfying the above range, a conductive layer having high electrical conductivity and high density can be preferably realized. In addition, the operability of the paste and the workability during film formation can be improved.
(B)介電質粉末
本文揭示的導電性糊除了所述(A)導電性粉末以外,可包含(B)介電質粉末作為主要構成鍛燒後的導體膜的成分。介電質粉末為如下成分:藉由配置於構成導電性粉末的粒子間,例如於導電性糊的鍛燒時抑制導電性粉末的來自低溫的燒結,或者可調整熱收縮率及鍛燒收縮歷程或鍛燒後的導電性膜的熱膨脹係數。介電質粉末的作用可為多種,特別是MLCC的內部電極層用的導電性糊中包含的介電質粉末為與介電質層共通或者類似的組成,藉此作為提高介電質層與內部電極層的燒結接合性的共存材料而較佳地發揮功能,因此較佳。(B) Dielectric powder In addition to the (A) conductive powder, the conductive paste disclosed herein may include (B) a dielectric powder as a component mainly constituting a conductor film after calcination. The dielectric powder is composed of particles that are arranged between particles constituting the conductive powder, for example, to suppress sintering of the conductive powder from low temperature during the calcination of the conductive paste, or to adjust the thermal shrinkage rate and the calcination shrinkage history. Or the thermal expansion coefficient of the conductive film after calcination. The dielectric powder can have various functions. In particular, the dielectric powder contained in the conductive paste for the internal electrode layer of the MLCC has a composition common to or similar to that of the dielectric layer, so as to improve the dielectric layer and The coexisting material of the sintered bondability of the internal electrode layer is preferred because it functions well.
關於介電質粉末的介電常數並無特別限制,可根據目標用途適宜選擇。作為一例,關於高介電常數系的MLCC的內部電極層形成用的導電性糊中使用的介電質粉末,相對介電常數典型而言為100以上,較佳為1000以上、例如1000~20000左右。關於所述介電質粉末的組成並無特別限定,可自各種無機材料中根據用途等適宜使用一種或兩種以上。作為介電質粉末,具體而言可列舉鈦酸鋇、鈦酸鍶、鈦酸鈣、鈦酸鎂、鈦酸鉍、鈦酸鋯、鈦酸鋅、鈮酸鎂酸鋇、鋯酸鈣等具有ABO3 所表示的鈣鈦礦結構的金屬氧化物、二氧化鈦(金紅石)、五氧化鈦、氧化鉿、氧化鋯、氧化鋁、鎂橄欖石(forsterite)、氧化鈮、鈦酸釹酸鋇、稀土類元素氧化物等其他金屬氧化物作為典型例。於所述內部電極層用途的糊中,介電質粉末例如可由鈦酸鋇(BaTiO3 )、鈦酸鍶及鋯酸鈣(CaZrO3 )等較佳地構成。另一方面,當然亦可使用相對介電常數未滿100的介電質材料(進而絕緣性材料)。The dielectric constant of the dielectric powder is not particularly limited, and may be appropriately selected depending on the intended use. As an example, the relative dielectric constant of the dielectric powder used in the conductive paste for forming an internal electrode layer of a high-dielectric-constant MLCC is typically 100 or more, preferably 1,000 or more, such as 1,000 to 20,000. about. The composition of the dielectric powder is not particularly limited, and one kind or two or more kinds can be suitably used from various inorganic materials depending on applications and the like. Specific examples of the dielectric powder include barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, zirconium titanate, zinc titanate, barium magnesium niobate, and calcium zirconate. ABO 3 metal oxide with perovskite structure, titanium dioxide (rutile), titanium pentoxide, hafnium oxide, zirconia, alumina, forsterite, niobium oxide, barium neodymium titanate, rare earth Element metal oxides and other metal oxides are typical examples. In the paste for use in the internal electrode layer, the dielectric powder may be preferably composed of barium titanate (BaTiO 3 ), strontium titanate, calcium zirconate (CaZrO 3 ), or the like. On the other hand, as a matter of course, a dielectric material (and thus an insulating material) having a relative dielectric constant of less than 100 can also be used.
構成介電質粉末的粒子的性狀、例如粒子的尺寸或形狀等只要包括於電極層的剖面中的最小尺寸(典型而言,電極層的厚度及/或寬度)內,則並無特別限定。介電質粉末的平均粒徑例如可根據糊的用途或電極層的尺寸(微細度)等適宜選擇。關於目標導電層,就容易確保規定的導電性的觀點而言,介電質粉末的平均粒徑較佳為小於所述導電性粉末的平均粒徑。於將介電質粉末的平均粒徑設為D2 、導電性粉末的平均粒徑設為D1 時,D1 及D2 通常較佳為D1 >D2 ,更佳為D2 ≦0.5×D1 ,進而佳為D2 ≦0.4×D1 ,例如亦可為D2 ≦0.3×D1 。另外,若介電質粉末的平均粒徑D2 過小,則亦容易產生介電質粉末的凝聚,因此欠佳。於所述方面上,作為大致的標準,較佳為0.03×D1 ≦D2 ,更佳為0.05×D1 ≦D2 ,例如亦可為0.1×D1 ≦D2 。例如,具體而言介電質粉末的平均粒徑適當地為大致數nm以上,較佳為5 nm以上,亦可為10 nm以上。另外,介電質粉末的平均粒徑亦可為大致數μm以下左右、例如1 μm以下、較佳為0.3 μm以下。作為一例,於為了形成MLCC的內部電極層的導電性糊中,介電質粉末的平均粒徑亦可為大致數nm~數百nm左右、例如5 nm~100 nm。The properties of the particles constituting the dielectric powder, such as the size or shape of the particles, are not particularly limited as long as they are included in the minimum size (typically, the thickness and / or width of the electrode layer) in the cross section of the electrode layer. The average particle diameter of the dielectric powder can be appropriately selected depending on, for example, the use of the paste, the size (fineness) of the electrode layer, and the like. The target conductive layer preferably has an average particle diameter of the dielectric powder that is smaller than the average particle diameter of the conductive powder, from the viewpoint of easily ensuring predetermined conductivity. When the average particle diameter of the dielectric powder is D 2 and the average particle diameter of the conductive powder is D 1 , D 1 and D 2 are usually preferably D 1 > D 2 , and more preferably D 2 ≦ 0.5. × D 1 , and more preferably D 2 ≦ 0.4 × D 1. For example, D 2 ≦ 0.3 × D 1 . In addition, if the average particle diameter D 2 of the dielectric powder is too small, aggregation of the dielectric powder is likely to occur, which is not preferable. In this respect, as a rough standard, it is preferably 0.03 × D 1 ≦ D 2 , more preferably 0.05 × D 1 ≦ D 2 , and for example, 0.1 × D 1 ≦ D 2 . For example, the average particle diameter of the dielectric powder is suitably approximately several nm or more, preferably 5 nm or more, or 10 nm or more. The average particle diameter of the dielectric powder may be approximately several μm or less, for example, 1 μm or less, and preferably 0.3 μm or less. As an example, in the conductive paste for forming the internal electrode layer of the MLCC, the average particle diameter of the dielectric powder may be approximately several nm to several hundreds nm, for example, 5 nm to 100 nm.
介電質粉末的含有比例並無特別限定。例如於形成MLCC的內部電極層的用途等中,於將導電性糊整體設為100質量%時,可為大致1質量%~20質量%、例如3質量%~15質量%。另外,作為介電質粉末相對於導電性粉末100質量份的比例,例如可為大致3質量份~35質量份、較佳為5質量份~30質量份、例如10質量份~25質量份。藉此,可適當地抑制導電性粉末的來自低溫的鍛燒,且提高鍛燒後的導體膜的電傳導性、緻密性等。The content ratio of the dielectric powder is not particularly limited. For example, in applications such as forming an internal electrode layer of an MLCC, when the entire conductive paste is 100% by mass, it may be approximately 1% to 20% by mass, for example, 3% to 15% by mass. The ratio of the dielectric powder to 100 parts by mass of the conductive powder may be, for example, approximately 3 to 35 parts by mass, preferably 5 to 30 parts by mass, for example, 10 to 25 parts by mass. Thereby, the low-temperature calcination of the conductive powder can be appropriately suppressed, and the electrical conductivity and the denseness of the conductor film after the calcination can be improved.
(C)黏合劑
黏合劑是於本文揭示的導電性糊中的有機成分中作為黏結劑發揮功能的材料。所述黏合劑典型而言有助於導電性糊中所含的粉末與基材的接合、以及構成所述粉末的粒子彼此的結合。另外,黏合劑溶解於後述的分散介質中作為媒液(可為液相介質)發揮功能。藉此,提高導電性糊的黏性且使粉末成分均勻且穩定地懸浮於媒液中,對粉末賦予流動性,並且有助於操作性的提高。所述黏合劑是以藉由鍛燒而消失作為前提的成分。因此,黏合劑較佳為於導體膜的鍛燒時燃燒掉的化合物。典型而言,較佳為無論環境如何分解溫度為500℃以下。關於黏合劑的組成等,並無特別限定,可適宜使用此種用途中使用的公知的各種有機化合物。(C) Binder A binder is a material that functions as a binder among the organic components in the conductive paste disclosed herein. The binder typically helps to bond the powder contained in the conductive paste and the substrate, and to bond the particles constituting the powder to each other. The binder is dissolved in a dispersion medium to be described later and functions as a vehicle (which may be a liquid medium). Thereby, the viscosity of the conductive paste is increased, the powder component is suspended uniformly and stably in the vehicle liquid, fluidity is imparted to the powder, and workability is improved. The binder is a component premised on disappearance by calcination. Therefore, the adhesive is preferably a compound that burns out when the conductor film is fired. Typically, the decomposition temperature is preferably 500 ° C or lower regardless of the environment. The composition and the like of the adhesive are not particularly limited, and various known organic compounds used in such applications can be suitably used.
作為所述黏合劑,例如可列舉:松香系樹脂、纖維素系樹脂、聚乙烯醇系樹脂、聚乙烯縮醛系樹脂、丙烯酸系樹脂、胺基甲酸酯系樹脂、環氧系樹脂、酚系樹脂、聚酯系樹脂、乙烯系樹脂等有機高分子化合物。亦取決於與所使用的溶劑的組合,因此不能一概而論,例如作為包含無機氧化物粉末且鍛燒溫度為較高溫的導電性糊的黏合劑,較佳為纖維素系樹脂、聚乙烯醇系樹脂、聚乙烯縮醛系樹脂、丙烯酸系樹脂等。Examples of the binder include rosin-based resin, cellulose-based resin, polyvinyl alcohol-based resin, polyvinyl acetal-based resin, acrylic resin, urethane-based resin, epoxy-based resin, and phenol. Organic polymer compounds such as resins, polyester resins, and vinyl resins. It also depends on the combination with the solvent used, so it cannot be generalized. For example, as a binder containing a conductive paste containing inorganic oxide powder and a relatively high calcination temperature, cellulose resins and polyvinyl alcohol resins are preferred. , Polyvinyl acetal resin, acrylic resin, etc.
纖維素系樹脂有助於無機氧化物粉末的分散性的提高,另外於將導電性糊供於印刷等的情況下,印刷體(配線膜)的形狀特性或對印刷作業的適應性優異等,因此較佳。纖維素系樹脂是指至少含有β-葡萄糖作為重覆單元的聚合物及其衍生物的全部。典型而言,可為將作為重覆單元的β-葡萄糖結構中的羥基的一部分或全部取代為烷氧基而得的化合物及其衍生物。烷氧基(RO- )中的烷基或芳基(R)的一部分或全部亦可被取代為羧基等酯基、硝基、鹵素、其他有機基。作為纖維素系樹脂,具體而言例如可列舉:甲基纖維素、乙基纖維素、丙氧基纖維素、羥基甲基纖維素、羥基乙基纖維素、羥基丙基纖維素、羥基丙基甲基纖維素、羥基丙基乙基纖維素、羧基甲基纖維素、羧基乙基纖維素、羧基丙基纖維素、羧基乙基甲基纖維素、乙酸鄰苯二甲酸纖維素、硝基纖維素等。Cellulose-based resins contribute to the improvement of the dispersibility of inorganic oxide powders. When conductive paste is used for printing, the shape characteristics of printed matter (wiring film) and the adaptability to printing work are excellent. So better. The cellulose-based resin refers to all the polymers and their derivatives containing at least β-glucose as a repeating unit. Typically, it may be a compound obtained by substituting a part or all of the hydroxyl groups in the β-glucose structure as the repeating unit with an alkoxy group and a derivative thereof. Alkyl or aryl portion of the group (R) or all may be substituted by an ester group to a carboxyl group, a nitro group, a halogen, an organic group other - alkoxy (RO). Specific examples of the cellulose-based resin include methyl cellulose, ethyl cellulose, propoxy cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl. Methyl cellulose, hydroxypropyl ethyl cellulose, carboxy methyl cellulose, carboxy ethyl cellulose, carboxy propyl cellulose, carboxy ethyl methyl cellulose, cellulose acetate phthalate, nitro fibers Su et al.
聚乙烯醇系樹脂使無機氧化物粉末的分散性良好且柔軟,因此於將導電性糊供於印刷等的情況下,印刷體(配線膜)的密接性、印刷性等優異等,因此較佳。聚乙烯醇系樹脂是指至少含有乙烯醇結構作為重覆單元的聚合物及其衍生物的全部。典型而言,亦可為包含由乙烯醇聚合而成的結構的聚乙烯醇(polyvinylalcohol,PVA)或利用醇對所述PVA進行縮醛化而得的聚乙烯縮醛樹脂、以及該些的衍生物等。其中,具有利用丁醇對PVA進行縮醛化的結構的聚乙烯丁醛系樹脂(polyvinyl butyral,PVB)提高印刷體的形狀特性,因此更佳。另外,該些聚乙烯縮醛樹脂亦可為如下共聚物(包含接枝共聚物)等:以聚乙烯縮醛為主單體,含有與所述主單體具有共聚性的副單體。作為副單體,例如可列舉乙烯、酯、(甲基)丙烯酸酯、乙酸乙烯酯等。聚乙烯縮醛樹脂中的縮醛化的比例並無特別限制,例如較佳為50%以上。The polyvinyl alcohol-based resin has good dispersibility of the inorganic oxide powder and is soft. Therefore, when a conductive paste is used for printing, the printed matter (wiring film) has excellent adhesion, printability, etc., and is therefore preferred. . The polyvinyl alcohol-based resin refers to all the polymers and derivatives thereof that contain at least a vinyl alcohol structure as a repeating unit. Typically, it may be a polyvinyl alcohol (PVA) containing a structure obtained by polymerizing vinyl alcohol, or a polyvinyl acetal resin obtained by acetalizing the PVA with an alcohol, and a derivative thereof. Things. Among them, a polyvinyl butyral (PVB) resin having a structure in which PVA is acetalized with butanol is more preferable because it improves the shape characteristics of a printed body. In addition, these polyethylene acetal resins may also be copolymers (including graft copolymers) and the like: a polyethylene acetal is a main monomer, and a secondary monomer having a copolymerizability with the main monomer is contained. Examples of the secondary monomer include ethylene, esters, (meth) acrylates, and vinyl acetate. The ratio of acetalization in the polyvinyl acetal resin is not particularly limited, but is preferably 50% or more.
丙烯酸系樹脂於富有黏著性及柔軟性,不論鍛燒環境如何鍛燒殘渣更少的方面較佳。作為丙烯酸系樹脂,是指例如至少含有(甲基)丙烯酸烷基酯作為構成單體成分的聚合物及其衍生物的全部。典型而言,亦可為包含100質量%(甲基)丙烯酸烷基酯作為構成單體成分的均聚物、或如下共聚物(包含接枝共聚物)等,所述共聚物(包含接枝共聚物)以(甲基)丙烯酸烷基酯為主單體,含有與所述主單體具有共聚性的副單體。作為副單體,可列舉(甲基)丙烯酸-2-羥基乙酯、(甲基)丙烯酸二甲基胺基乙酯、乙烯醇系單體、導入了二烷基胺基、羧基、烷氧基羰基等的共聚性單體。作為丙烯酸系樹脂,具體而言例如可列舉聚(甲基)丙烯酸、氯乙烯/丙烯酸接枝共聚樹脂、乙烯縮醛/丙烯酸接枝共聚樹脂等。再者,本說明書中,「(甲基)丙烯酸酯」等的表述作為表示包括丙烯酸酯及/或甲基丙烯酸酯的用語而使用。The acrylic resin is preferable in that it is rich in adhesiveness and flexibility, and has fewer calcination residues regardless of the calcination environment. The acrylic resin refers to, for example, the entirety of the polymer and its derivatives containing at least an alkyl (meth) acrylate as a constituent monomer component. Typically, it may be a homopolymer containing 100% by mass of alkyl (meth) acrylate as a constituent monomer component, or a copolymer (including a graft copolymer), etc. The copolymer) is mainly composed of an alkyl (meth) acrylate, and contains a sub-monomer having copolymerizability with the main monomer. Examples of the secondary monomer include 2-hydroxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, a vinyl alcohol-based monomer, a dialkylamino group, a carboxyl group, and an alkoxy group introduced. Copolymerizable monomers such as carbonyl. Specific examples of the acrylic resin include poly (meth) acrylic acid, vinyl chloride / acrylic acid graft copolymer resin, and ethylene acetal / acrylic acid graft copolymer resin. In addition, in this specification, expressions, such as "(meth) acrylate", are used as the term which shows that acrylate and / or methacrylate are included.
所述黏合劑可使用任一種,亦可組合使用兩種以上。另外雖未明確記載,但亦可使用將所述任意兩種以上的樹脂的單體成分共聚而成的共聚物、嵌段共聚物等。另外,黏合劑的含量並無特別限制。為了良好地調整導電性糊的性狀或糊印刷體(包括乾燥膜)的性狀,例如相對於導電性粉末100質量份,黏合劑的含量亦可為0.5質量份以上、較佳為1質量份以上、更佳為1.5質量份以上、例如2質量份以上的比例。另一方面,黏合劑樹脂有鍛燒殘渣增大的可能性,因此過剩的含有的情況欠佳。就所述觀點而言,相對於導電性粉末100質量份,黏合劑的含量可設為10質量份以下、較佳為7質量份以下、更佳為5質量份以下、例如4質量份以下。Any of these adhesives can be used, or two or more of them can be used in combination. Although not explicitly described, a copolymer, a block copolymer, or the like obtained by copolymerizing monomer components of any two or more of the resins may be used. The content of the binder is not particularly limited. In order to properly adjust the properties of the conductive paste or the properties of the paste printing body (including the dry film), for example, the content of the binder may be 0.5 parts by mass or more, and preferably 1 part by mass or more, based on 100 parts by mass of the conductive powder. The ratio is more preferably 1.5 parts by mass or more, for example, 2 parts by mass or more. On the other hand, since the binder resin may increase the calcination residue, the excessive content is not preferable. From this viewpoint, the content of the binder may be 10 parts by mass or less, preferably 7 parts by mass or less, more preferably 5 parts by mass or less, for example 4 parts by mass or less, based on 100 parts by mass of the conductive powder.
(D)分散介質
分散介質是在本文揭示的導電性糊中的有機成分中用於將粉末製成分散狀態的液狀介質,例如是用於在保持所述分散性的狀態下賦予優異的流動性的要素。另外,分散介質溶解所述黏合劑,作為媒液發揮功能。所述分散介質亦為以藉由乾燥、鍛燒而消失作為前提的成分。關於分散介質,並無特別限制,可適宜使用此種導電性糊中使用的有機溶劑。雖亦取決於例如與黏合劑的組合,但就成膜穩定性等觀點而言,可將沸點約180℃以上且300℃以下左右、例如200℃以上且250℃以下左右的高沸點有機溶劑作為主成分(佔50體積%以上的成分)。(D) Dispersion medium A dispersion medium is a liquid medium used to disperse a powder among organic components in the conductive paste disclosed herein, and is used to impart excellent flow while maintaining the dispersibility. Elements of sex. The dispersing medium dissolves the binder and functions as a vehicle. The dispersion medium is also a component premised on disappearance by drying and calcination. The dispersion medium is not particularly limited, and an organic solvent used in such a conductive paste can be suitably used. Although it also depends on the combination with, for example, a high-boiling-point organic solvent having a boiling point of about 180 ° C or higher and 300 ° C or lower, such as 200 ° C or higher and 250 ° C or lower, from the viewpoint of film formation stability and the like. The main component (component that accounts for more than 50% by volume).
作為分散介質,例如具體而言可列舉:香紫蘇醇、香茅醇、植醇、香葉基芳樟醇、酯醇(texanol)、苄醇、苯氧基乙醇、1-苯氧基-2-丙醇、萜品醇、二氫萜品醇、異冰片、丁基卡必醇、二乙二醇等醇系溶劑;萜品醇乙酸酯、二氫萜品醇乙酸酯、異冰片乙酸酯、卡必醇乙酸酯、二乙二醇單丁醚乙酸酯等酯系溶劑;礦油精(mineral spirit)等。其中,可較佳地使用醇系溶劑或酯系溶劑。Specific examples of the dispersion medium include sclareol, citronellol, phytol, geranyl linalool, texanol, benzyl alcohol, phenoxyethanol, and 1-phenoxy-2-propane Alcohol solvents such as alcohol, terpineol, dihydroterpineol, isobornyl, butylcarbitol, diethylene glycol; terpineol acetate, dihydroterpineol acetate, isobornyl acetate Ester solvents such as esters, carbitol acetate, diethylene glycol monobutyl ether acetate; mineral spirits, etc. Among them, an alcohol-based solvent or an ester-based solvent can be preferably used.
導電性糊中的(C)分散介質的比例並無特別限定,於將糊整體設為100質量%時,可為大致70質量%以下、典型而言5質量%~60質量%、例如30質量%~50質量%。藉由滿足所述範圍,可對糊賦予適度的流動性,可提高成膜時的作業性。另外,可提高糊的自調平性(self-levelling),實現更平滑的表面的導體膜。The proportion of the (C) dispersion medium in the conductive paste is not particularly limited. When the entire paste is 100% by mass, it may be approximately 70% by mass or less, typically 5 to 60% by mass, for example, 30% by mass. % To 50% by mass. By satisfying the above range, moderate fluidity can be imparted to the paste, and workability during film formation can be improved. In addition, the self-levelling of the paste can be improved and a smoother surface conductor film can be realized.
(E)其他添加劑
再者,本文揭示的導電性糊可於不顯著損及本文揭示的技術的效果的範圍內,包含已知一般的導電性糊中可使用的各種有機添加劑。所謂所述有機添加劑,例如為分散劑、增黏劑、塑化劑、pH調整劑、穩定劑、調平劑、消泡劑、抗氧化劑、防腐劑、著色劑(顏料、染料等)等。例如,於使用作為構成導體膜的主體的導電性粉末及介電質粉末等粉末的情況下,若平均粒徑未滿1 μm左右,則所述粉末只要不實施特別的表面處理等,則有時於糊製備過程中及糊剛製備後會發生凝聚。關於所述傾向,於使用表面活性可顯著提高的超微粉或奈米粒子(例如,平均粒徑為0.5 μm以下的粉末)作為導電性粉末等的情況下等變得更顯著。因此,本文揭示的導電性糊可較佳地包含分散劑作為其他添加劑。(E) Other additives In addition, the conductive paste disclosed herein may include various organic additives that can be used in general conductive pastes within a range that does not significantly impair the effect of the technology disclosed herein. The organic additives include, for example, a dispersant, a thickener, a plasticizer, a pH adjuster, a stabilizer, a leveling agent, a defoamer, an antioxidant, a preservative, and a colorant (pigment, dye, etc.). For example, when using powders such as conductive powder and dielectric powder as the main body of the conductive film, if the average particle diameter is less than about 1 μm, the powder may be provided without special surface treatment or the like. Aggregation sometimes occurs during the preparation of the paste and immediately after the preparation of the paste. This tendency is more significant when using ultrafine powder or nano particles (for example, a powder having an average particle diameter of 0.5 μm or less) as the conductive powder or the like, which can significantly improve the surface activity. Therefore, the conductive paste disclosed herein may preferably include a dispersant as other additives.
分散劑為如下成分:於使粉末分散於分散介質中時抑制構成粉末的粒子彼此的凝聚,使粒子均勻地分散於分散介質中。分散劑具備直接吸附於粒子的固體表面而使粒子與分散介質之間的固液界面穩定化的功能。分散劑較佳為於導電性糊的鍛燒時燃燒掉。換言之,分散劑較佳為分解溫度相較於導電性糊的鍛燒溫度而言充分低(典型而言為600℃以下)。The dispersant is a component that suppresses agglomeration of particles constituting the powder when the powder is dispersed in a dispersion medium, and uniformly disperses the particles in the dispersion medium. The dispersant has a function of directly adsorbing on the solid surface of the particles and stabilizing the solid-liquid interface between the particles and the dispersion medium. The dispersant is preferably burned off during the calcination of the conductive paste. In other words, the dispersant preferably has a decomposition temperature sufficiently lower than the calcination temperature of the conductive paste (typically, 600 ° C. or lower).
關於分散劑的種類等,並無特別限定,可自公知的各種分散劑中視需要使用一種或兩種以上。典型而言,可適宜選擇使用對後述的媒液(黏合劑及分散介質的混合物)具有充分的相容性者。分散劑的分類的方法可為多種,作為分散劑,亦可為所謂的界面活性劑型分散劑(亦稱為低分子型分散劑)、高分子型分散劑、無機型分散劑等中的任一種。另外,該些分散劑可為陰離子性、陽離子性、兩性或非離子性中的任一種。換言之,分散劑是於分子結構中具有陰離子性基、陽離子性基、兩性基及非離子性基中的至少一種官能基的化合物,典型而言可為所述官能基可直接吸附於粒子的固體表面的化合物。再者,所謂界面活性劑,是指如下兩親媒性物質:於分子結構內具備親水性部位與親油性部位,具有該些以共價鍵鍵結而成的化學結構。The type of the dispersant is not particularly limited, and one or two or more kinds can be used as needed from various known dispersants. Typically, those having sufficient compatibility with a vehicle (a mixture of a binder and a dispersion medium) described later can be appropriately selected and used. There are a variety of methods for classifying dispersants. As the dispersant, any one of a so-called surfactant-type dispersant (also referred to as a low-molecular-type dispersant), a polymer-type dispersant, and an inorganic dispersant may be used. . These dispersants may be any of anionic, cationic, amphoteric, and nonionic. In other words, the dispersant is a compound having at least one functional group among anionic groups, cationic groups, amphoteric groups, and nonionic groups in the molecular structure. Typically, the dispersant may be a solid in which the functional group can be directly adsorbed to particles. Surface compounds. The term “surfactant” refers to an amphiphilic substance that includes a hydrophilic portion and a lipophilic portion in a molecular structure and has a chemical structure formed by covalent bonding.
關於分散劑,作為界面活性劑型分散劑,例如具體而言可列舉:以烷基磺酸鹽為主體的分散劑、以四級銨鹽為主體的分散劑、以高級醇的環氧烷化合物為主體的分散劑、以多元醇酯化合物為主體的分散劑、以烷基多胺系化合物為主體的分散劑等。作為高分子型分散劑,例如可列舉:以羧酸或聚羧酸等脂肪酸鹽為主體的分散劑、以及以其一部分的羧酸基中的氫原子經烷基取代而成的聚羧酸部分烷基酯化合物為主體的分散劑、以聚羧酸烷基胺鹽為主體的分散劑、以聚羧酸的一部分具有烷基酯鍵的聚羧酸部分烷基酯化合物為主體的分散劑、以聚苯乙烯磺酸鹽、聚異戊二烯磺酸鹽、聚亞烷基多胺化合物為主體的分散劑、以萘磺酸鹽、萘磺酸福馬林縮合物鹽等磺酸系化合物為主體的分散劑、以聚乙二醇等親水性聚合物為主體的分散劑、以聚醚化合物為主體的分散劑、以聚(甲基)丙烯酸鹽、聚(甲基)丙烯醯胺等聚(甲基)丙烯酸系化合物為主體的分散劑等。作為無機型分散劑,例如可列舉以正磷酸鹽、偏磷酸鹽、聚磷酸鹽、焦磷酸鹽、三聚磷酸鹽、六偏磷酸鹽及有機磷酸鹽等磷酸鹽、硫酸鐵、硫酸亞鐵、氯化鐵及氯化亞鐵等鐵鹽、硫酸鋁、聚氯化鋁及鋁酸鈉等鋁鹽、硫酸鈣、氫氧化鈣及磷酸氫鈣等鈣鹽為主體的分散劑。Regarding the dispersant, examples of the surfactant-type dispersant include a dispersant mainly composed of an alkyl sulfonate, a dispersant mainly composed of a quaternary ammonium salt, and an alkylene oxide compound composed of a higher alcohol. A main dispersant, a main dispersant including a polyol ester compound, a main dispersant including an alkyl polyamine compound, and the like. Examples of the polymer-based dispersant include a dispersant mainly composed of a fatty acid salt such as a carboxylic acid or a polycarboxylic acid, and a polycarboxylic acid moiety in which a hydrogen atom in a part of the carboxylic acid group is substituted with an alkyl group. Dispersant mainly composed of alkyl ester compounds, dispersant composed mainly of polycarboxylic acid alkylamine salts, dispersant composed mainly of polycarboxylic acid partially alkyl ester compounds having alkyl ester bonds in part of polycarboxylic acids, Dispersants mainly composed of polystyrene sulfonate, polyisoprene sulfonate, and polyalkylene polyamine compounds, and sulfonic acid compounds such as naphthalene sulfonate and formalin condensate salt Dispersant mainly composed of hydrophilic polymers such as polyethylene glycol, dispersant composed mainly of hydrophilic polymers such as polyethylene glycol, dispersant composed mainly of polyether compounds, poly (meth) acrylates, poly (meth) acrylamides, etc. A (meth) acrylic compound-based dispersant and the like. Examples of the inorganic dispersant include phosphates such as orthophosphate, metaphosphate, polyphosphate, pyrophosphate, tripolyphosphate, hexametaphosphate, and organic phosphate; ferric sulfate; ferrous sulfate; Dispersants mainly composed of iron salts such as ferric chloride and ferrous chloride, aluminum salts such as aluminum sulfate, polyaluminum chloride and sodium aluminate, and calcium salts such as calcium sulfate, calcium hydroxide, and calcium hydrogen phosphate.
再者,所述分散劑可單獨包含任一種,亦可組合包含兩種以上。另外,分散劑的種類並無特別限定,就以少量的分散劑的添加而使更微細的導電性粉末及介電質粉末長期有效地分散的目的而言,若使用可顯現出立體阻礙所引起的排斥效果的高分子型分散劑,則較佳。該情況下的分散劑的重量平均分子量並無特別限制,作為較佳的一例,較佳為設為300~50000左右、例如500~20000。In addition, the dispersant may include any one kind alone, or may include two or more kinds in combination. In addition, the type of the dispersant is not particularly limited. For the purpose of dispersing finer conductive powders and dielectric powders efficiently for a long period of time with the addition of a small amount of a dispersant, the use of the dispersant may cause a three-dimensional obstacle A polymer-type dispersant having a repellent effect is preferred. The weight average molecular weight of the dispersant in this case is not particularly limited, and as a preferred example, it is preferably set to about 300 to 50,000, for example, 500 to 20,000.
再者,所述有機添加劑可單獨包含任一種,亦可組合包含兩種以上。另外,所述有機添加劑的含量可於不顯著阻礙本文揭示的導電性糊的性狀的範圍內適宜調整。例如,可根據所述有機添加劑的性狀及其目的以適當的比例含有。大致而言,例如分散劑通常以相對於粉末成分的總質量而言約5質量%以下、例如3質量%以下、典型而言1質量%以下且約0.01質量%以上的比例含有。再者,含有阻礙導電性粉末或無機粉末的燒結性等的成分、或阻礙該些的量的添加劑欠佳。就所述觀點而言,於包含有機添加劑的情況下,該些成分的總含量較佳為導電性糊整體的約10質量%以下,更佳為5質量%以下,尤佳為3質量%以下。In addition, the organic additives may include any one kind alone, or may include two or more kinds in combination. In addition, the content of the organic additive may be appropriately adjusted within a range that does not significantly hinder the properties of the conductive paste disclosed herein. For example, it may be contained in an appropriate ratio according to the properties of the organic additive and its purpose. Generally, for example, the dispersant is contained in a proportion of about 5 mass% or less, for example, 3 mass% or less, typically 1 mass% or less and about 0.01 mass% or more with respect to the total mass of the powder component. Furthermore, it is not preferable to contain a component that inhibits the sinterability of the conductive powder or inorganic powder or the like, or an additive that inhibits these amounts. From the viewpoint, when organic additives are included, the total content of these components is preferably about 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. .
導電性糊通常可藉由如下方式製備:於將作為有機成分的(C)黏合劑與(D)分散介質預先混合而製備媒液後,於所述媒液中將(A)導電性粉末與(B)介電質粉末混合並揉混。於本文揭示的導電性糊中,為了將透過率變化速度抑制為0.003以下且實現糊中的(A)導電性粉末及(B)介電質粉末的高分散穩定性,最重要的是摻合所述構成材料。所述導電性糊的製備方法於可實現所述透過率變化速度的範圍內並無特別限制。作為導電性糊的製備方法的一例,於後述的實施例中進行詳細說明,可將(A)導電性粉末與(B)介電質粉末預先分散於不同的(D)分散介質中並製備成漿料狀,其後以漿料的形態混合導電性粉末與介電質粉末,藉此可分散性良好地將兩者摻合。The conductive paste can generally be prepared by mixing the (C) binder and (D) dispersion medium as organic components in advance to prepare a vehicle solution, and then (A) the conductive powder and (B) The dielectric powder is mixed and kneaded. In the conductive paste disclosed herein, in order to suppress the rate of change in transmittance to 0.003 or less and achieve high dispersion stability of (A) conductive powder and (B) dielectric powder in the paste, the most important thing is blending. The constituent material. The method for preparing the conductive paste is not particularly limited within a range in which the transmittance change rate can be achieved. As an example of a method for preparing a conductive paste, detailed description will be given in Examples described later. The conductive powder (A) and the dielectric powder (B) may be dispersed in different (D) dispersion media in advance and prepared into The slurry is then mixed with the conductive powder and the dielectric powder in the form of a slurry, whereby the two are blended with good dispersibility.
再者,有機成分中的(C)黏合劑若最初添加於包含(A)導電性粉末的漿料(以下,稱為導電性粉末漿料)或包含(B)介電質粉末的漿料(以下,稱為介電質粉末漿料)中,則妨礙使該些粉末高分散。因此,關於(C)黏合劑,較佳為藉由與(D)分散介質的一部分混合而預先製備媒液,對於導電性粉末漿料與介電質粉末漿料的混合漿料以媒液的狀態混合。以所述方式製備的導電性糊的透過率變化速度較佳為未滿0.003,更佳為0.0025以下,尤佳為0.002以下。所述導電性糊(混合漿料)可長期強烈地維持其高分散狀態,因此較佳。In addition, if the (C) binder in the organic component is first added to a slurry containing conductive powder (A) (hereinafter referred to as a conductive powder slurry) or a slurry containing (B) a dielectric powder ( In the following, referred to as a dielectric powder slurry), the high dispersion of these powders is prevented. Therefore, it is preferable that the (C) binder is prepared in advance by mixing with a part of the (D) dispersion medium, and the mixed slurry of the conductive powder slurry and the dielectric powder slurry is prepared by using the medium liquid. State mixed. The rate of change in transmittance of the conductive paste prepared as described above is preferably less than 0.003, more preferably 0.0025 or less, and even more preferably 0.002 or less. The conductive paste (mixed paste) is preferred because it can maintain its high dispersion state strongly for a long period of time.
此處,預先製備的導電性粉末漿料與介電質粉末漿料較佳為於各自的漿料中以前所未有的較佳的狀態使導電性粉末或介電質粉末預先高度地分散。所謂所述分散條件亦取決於作為對象的導電性粉末及介電質粉末的材質(組成等)或平均粒徑、糊濃度、所使用的攪拌裝置或分散裝置等的構成,因此不能一概而論。例如,作為一例,若將先前進行的擴散處理中的擴散強度設為1,則本文揭示的技術中製備導電性粉末漿料及介電質粉末漿料時的攪拌強度例如可設為0.1(倍)以上,亦可為0.5以上,例如較佳為1以上,更佳為1.5以上,進而佳為1.8以上,尤佳為2以上。攪拌強度的上限可設為裝置構成的上限,例如若將先前進行的擴散處理中的擴散強度設為1,則可以5左右作為標準。而且,於透過率變化速度的調整時,可例如預先製作所需的調配的導電性糊並確認透過率變化速度,以所述透過率變化速度成為0.003以下的方式一點一點地調整所述導電性糊的攪拌條件。更具體而言,例如於利用現有方法將攪拌強度設定為30 m/s左右而製備糊的情況下,例示了於30 m/s~60 m/s左右的範圍、例如45 m/s~60 m/s左右的範圍內提高攪拌強度。另外,另一方面,於利用現有方法將攪拌強度設定為7 m/s左右而製備糊的情況下,例示了於7 m/s~20 m/s左右的範圍、例如10 m/s~20 m/s左右的範圍內提高攪拌強度。Here, it is preferable that the conductive powder or the dielectric powder slurry prepared in advance has the conductive powder or the dielectric powder highly dispersed in the respective slurry in a better state than ever before. The above-mentioned dispersion conditions also depend on the materials (composition, etc.), average particle diameter, paste concentration, and configuration of the stirring device or dispersion device used for the target conductive powder and dielectric powder, so they cannot be generalized. For example, if the diffusion strength in the previously performed diffusion treatment is set to 1, for example, the stirring strength when preparing the conductive powder slurry and the dielectric powder slurry in the technique disclosed herein can be set to 0.1 (times) ) Or more may be 0.5 or more, for example, preferably 1 or more, more preferably 1.5 or more, still more preferably 1.8 or more, and even more preferably 2 or more. The upper limit of the stirring intensity can be set to the upper limit of the device configuration. For example, if the diffusion intensity in the previously performed diffusion process is set to 1, the standard may be about 5. In addition, when adjusting the transmittance change rate, for example, it is possible to prepare a conductive paste to be prepared in advance and confirm the transmittance change rate, and adjust the transmittance rate little by little so that the transmittance change rate becomes 0.003 or less. Stirring conditions for conductive paste. More specifically, for example, when a paste is prepared by setting the stirring intensity to about 30 m / s by a conventional method, a range of about 30 m / s to 60 m / s, for example, 45 m / s to 60 is exemplified. Increase the stirring intensity in the range of about m / s. On the other hand, in the case where a paste is prepared by setting the stirring intensity to about 7 m / s by a conventional method, a range of about 7 m / s to 20 m / s, for example, 10 m / s to 20 is exemplified. Increase the stirring intensity in the range of about m / s.
另外,此時可使用無介質的攪拌裝置或分散裝置對至少導電性粉末漿料進行攪拌、分散處理。再者,所謂無介質的攪拌裝置或分散裝置是指如下攪拌或分散裝置:不具備用以對作為攪拌或分散對象的流體帶來衝擊等攪拌、分散作用的硬質介質(例如亦稱為粉碎構件、可動構件、介質(media)等)。所述無介質的攪拌或分散裝置的驅動力例如為壓縮空氣、蒸汽、加熱氣流等高速流體、超音波、氣穴泡沫(Cavitation bubble)等,藉由利用所述驅動力的衝擊或撞擊、粒子的相互碰撞、相互摩擦等可顯現出攪拌或分散作用。例如,例示了氣流粉碎式磨機、噴射磨機、超音波噴射磨機、十字噴射磨機(Cross Jet Mill)等。若利用所述無介質的攪拌、分散裝置,則硬質介質與作為攪拌、分散對象的流體中所含的固體一次粒子直接接觸等並發生作用,不會導致一次粒子的變形、例如箔化等。In addition, at this time, at least the conductive powder slurry can be stirred and dispersed using a medium-less stirring device or a dispersing device. In addition, the medium-free stirring device or dispersing device refers to a stirring or dispersing device that does not have a rigid medium (such as a pulverizing member) that does not have a stirring or dispersing effect such as to impinge on a fluid to be stirred or dispersed. , Movable members, media, etc.). The driving force of the medium-free stirring or dispersing device is, for example, high-speed fluid such as compressed air, steam, or heated airflow, ultrasonic waves, or cavitation bubbles, and the like. Collision, friction, etc., can show agitation or dispersion. For example, jet mills, jet mills, ultrasonic jet mills, cross jet mills, and the like are exemplified. When the medium-free stirring and dispersing device is used, the hard medium and the primary solid particles contained in the fluid to be stirred and dispersed are brought into direct contact with each other and act, without causing deformation of the primary particles, such as foiling.
關於另一者的介電質漿料,對於攪拌裝置或分散裝置無任何限制。例如,可使用所述無介質的攪拌裝置或分散裝置,亦可使用介質式的攪拌裝置或分散裝置。無需再次例示,作為介質式的攪拌、分散裝置,例如可列舉:球磨機、珠磨機、膠體磨機、錘磨機、研缽、圓盤粉碎機、輥磨機等。Regarding the other dielectric paste, there are no restrictions on the stirring device or the dispersing device. For example, the medium-free stirring device or dispersion device may be used, or a medium-type stirring device or dispersion device may be used. Without further exemplification, examples of the media-type stirring and dispersing device include a ball mill, a bead mill, a colloid mill, a hammer mill, a mortar, a disk mill, and a roll mill.
以所述方式預先將導電性粉末與介電質粉末分開而製備高分散的漿料,藉此可於將兩者混合時較佳地抑制任一種粒子的凝聚,可實現高分散狀態。結果,即便於例如對導電性糊實施離心沈降處理並加速地促進沈降的情況下,關於本文揭示的導電性糊,亦可高度地抑制導電性粉末及介電質粉末的沈降。再者,於包含分散劑的態樣中,關於導電性粉末漿料、介電質粉末漿料及導電性糊的任一者,可包含分散劑,亦可不含。關於包含分散劑的漿料,可於同一時機或不同時機將粉體材料與分散劑於分散介質中進行攪拌、分散。In this way, the conductive powder and the dielectric powder are separated in advance to prepare a highly-dispersed slurry, whereby the agglomeration of any one kind of particles can be better suppressed when the two are mixed, and a highly-dispersed state can be achieved. As a result, even when the conductive paste is subjected to a centrifugal sedimentation treatment to accelerate the sedimentation, the conductive paste disclosed herein can highly suppress the sedimentation of the conductive powder and the dielectric powder. Furthermore, in the aspect including a dispersant, any of the conductive powder slurry, the dielectric powder slurry, and the conductive paste may contain a dispersant or may not contain it. Regarding the slurry containing a dispersant, the powder material and the dispersant can be stirred and dispersed in a dispersion medium at the same time or at different times.
關於本文揭示的導電性糊,如上所述導電性粉末及介電質粉末的分散穩定性極高。因此,導電性糊向基材的供給可無特別限制地採用公知的各種供給方法。作為所述供給方法,例如可列舉:網版印刷、凹版印刷、平板印刷及噴墨印刷等印刷法、噴塗法、浸漬塗佈法等。特別是於形成MLCC的內部電極層的情況下,可較佳地採用可高速印刷的凹版印刷法、網版印刷法等。As for the conductive paste disclosed herein, the dispersion stability of the conductive powder and the dielectric powder as described above is extremely high. Therefore, the supply of the conductive paste to the substrate can be performed by any of various known supply methods without any particular limitation. Examples of the supply method include printing methods such as screen printing, gravure printing, lithographic printing, and inkjet printing, spray coating methods, and dip coating methods. In particular, in the case of forming the internal electrode layer of the MLCC, a gravure printing method, a screen printing method, or the like capable of high-speed printing can be preferably used.
[用途]
本文揭示的導電性糊如上所述即便於例如連續施加100分鐘的4000 rpm下的離心沈降處理的情況下,導電性糊中所含的粒子亦不會完全沈降而與分散介質分離,其沈降得到抑制。所述離心沈降處理的條件是相當於例如藉由靜置導電性糊而進行的沈降處理製程的數月~數年左右的加速試驗。因此,所述導電性糊於糊製備後的長期保管性優異,例如亦可於量產步驟中一次性地製備大量的糊並長時間使用(供於印刷)。所述特徵亦使得使用所述導電性糊而形成的印刷塗膜的印刷性穩定,例如亦有助於印刷塗膜的厚度、密度等的均質性的提高。另外,於印刷塗膜中亦可維持導電性粉末與介電質粉末高度地分散的狀態。結果即便對所述印刷塗膜進行鍛燒,亦可較佳地抑制導電性粒子的燒結及異常晶粒成長。於所述方面,所述導電性糊亦可於特別要求鍛燒後的導體膜的均質性或表面平滑性等的用途中較佳地使用。作為代表性的用途,可列舉積層陶瓷電子零件中的電極層的形成。本文揭示的導電性糊例如可較佳地用於各邊為5 mm以下、例如1 mm以下的小型的MLCC的內部電極層的形成。尤其,可較佳地用於介電質層的厚度為1 μm以下水準的小型、大容量型的MLCC的內部電極的製作。[use]
As described above, even if the conductive paste is subjected to centrifugal sedimentation treatment at 4000 rpm for 100 minutes as described above, the particles contained in the conductive paste are not completely settled and separated from the dispersion medium. inhibition. The conditions of the centrifugal sedimentation treatment are, for example, an accelerated test corresponding to several months to several years in a sedimentation treatment process performed by leaving the conductive paste to stand. Therefore, the conductive paste is excellent in long-term storage after the preparation of the paste, and for example, a large amount of paste can be prepared at one time in a mass production step and used for a long time (for printing). This feature also stabilizes the printability of the printed coating film formed using the conductive paste, and for example, contributes to the improvement of the uniformity of the thickness and density of the printed coating film. In addition, the state in which the conductive powder and the dielectric powder are highly dispersed can also be maintained in the printed coating film. As a result, even if the printed coating film is calcined, sintering of the conductive particles and abnormal grain growth can be better suppressed. In this aspect, the conductive paste can also be preferably used in applications where homogeneity or surface smoothness of a conductor film after calcination is particularly required. Typical applications include formation of an electrode layer in a multilayer ceramic electronic component. The conductive paste disclosed herein can be preferably used, for example, for forming an internal electrode layer of a small MLCC having sides of 5 mm or less, for example, 1 mm or less. In particular, it can be preferably used for the production of internal electrodes of small, large-capacity MLCCs with a dielectric layer thickness of 1 μm or less.
再者,本說明書中,所謂「陶瓷電子零件」是表示具有結晶的陶瓷基材或非晶的陶瓷(玻璃陶瓷)基材的電子零件常見的用語。例如,包含陶瓷製的基材的晶片電感器、高頻濾波器、陶瓷電容器、高溫鍛燒積層陶瓷(High Temperature Co-fired Ceramics,HTCC)基材、低溫鍛燒積層陶瓷(Low Temperature Co-fired Ceramics,LTCC)基材等是此處所述的「陶瓷電子零件」中包含的典型例。In addition, in this specification, a "ceramic electronic component" means the term common to the electronic component which has a crystalline ceramic substrate or an amorphous ceramic (glass ceramic) substrate. For example, chip inductors including ceramic-based substrates, high-frequency filters, ceramic capacitors, High Temperature Co-fired Ceramics (HTCC) substrates, and Low Temperature Co-fired ceramics Ceramics (LTCC) substrates are typical examples included in the "ceramic electronic components" described herein.
作為構成陶瓷基材的陶瓷材料,例如可列舉:鈦酸鋇(BaTiO3 )、氧化鋯(ZrO2 )、氧化鎂(MgO)、氧化鋁(Al2 O3 )、二氧化矽(SiO2 )、氧化鋅(ZnO)、氧化鈦(TiO2 )、氧化鈰(CeO2 )、氧化釔(Y2 O3 )等氧化物系材料;堇青石(2MgO·2Al2 O3 ·5SiO2 )、莫來石(3Al2 O3 ·2SiO2 )、鎂橄欖石(2MgO·SiO2 )、塊滑石(MgO·SiO2 )、賽隆(Si3 N4 -AlN-Al2 O3 )、鋯石(ZrO2 ·SiO2 )、鐵氧體(M2 O·Fe2 O3 )等複合氧化物系材料;氮化矽(Si3 N4 )、氮化鋁(AlN)、氮化硼(BN)等氮化物系材料;碳化矽(SiC)、碳化硼(B4 C)等碳化物系材料;羥基磷灰石等氫氧化物系材料等。該些可單獨含有一種,亦可以混合有兩種以上的混合物、或者以將兩種以上複合化的複合體的形式含有。Examples of the ceramic material constituting the ceramic substrate include barium titanate (BaTiO 3 ), zirconia (ZrO 2 ), magnesium oxide (MgO), aluminum oxide (Al 2 O 3 ), and silicon dioxide (SiO 2 ). , Zinc oxide (ZnO), titanium oxide (TiO 2 ), cerium oxide (CeO 2 ), yttrium oxide (Y 2 O 3 ) and other oxide-based materials; cordierite (2MgO · 2Al 2 O 3 · 5SiO 2 ), Mo Lairite (3Al 2 O 3 · 2SiO 2 ), forsterite (2MgO · SiO 2 ), block talc (MgO · SiO 2 ), sialon (Si 3 N 4 -AlN-Al 2 O 3 ), zircon ( ZrO 2 · SiO 2 ), ferrite (M 2 O · Fe 2 O 3 ) and other composite oxide materials; silicon nitride (Si 3 N 4 ), aluminum nitride (AlN), boron nitride (BN) And other nitride-based materials; silicon carbide (SiC), boron carbide (B 4 C) and other carbide-based materials; hydroxyapatite and other hydroxide-based materials. These may be contained singly, or as a mixture of two or more kinds, or in the form of a composite of two or more kinds.
[積層陶瓷電容器]
圖1A是示意性地表示積層陶瓷電容器(MLCC)1的剖面圖。MLCC1是將多個介電質層20與內部電極層30交替且一體地積層而構成的晶片型的電容器。於包含介電質層20與內部電極層30的積層晶片10的側面設置有一對外部電極40。作為一例,內部電極層30以積層順序交替地連接於不同的外部電極40上。藉此,構築小型大容量的MLCC1,其是包含介電質層20與夾著該介電質層20的一對內部電極層30的電容器結構並聯連接而成。MLCC1的介電質層20由陶瓷構成。內部電極層30是由本文揭示的導電性糊的鍛燒體構成。所述MLCC1例如藉由以下順序而較佳地製造。[Multilayer Ceramic Capacitor]
FIG. 1A is a cross-sectional view schematically showing a multilayer ceramic capacitor (MLCC) 1. MLCC1 is a chip-type capacitor in which a plurality of dielectric layers 20 and internal electrode layers 30 are alternately and integrally laminated. A pair of external electrodes 40 is provided on a side surface of the multilayer wafer 10 including the dielectric layer 20 and the internal electrode layer 30. As an example, the internal electrode layers 30 are alternately connected to different external electrodes 40 in a stacking order. Thereby, a small and large-capacity MLCC 1 is constructed, and a capacitor structure including a dielectric layer 20 and a pair of internal electrode layers 30 sandwiching the dielectric layer 20 is connected in parallel. The dielectric layer 20 of the MLCC1 is made of ceramic. The internal electrode layer 30 is made of a fired body of the conductive paste disclosed herein. The MLCC1 is preferably manufactured by the following procedure, for example.
圖1B是示意性地表示未鍛燒的積層晶片10(未鍛燒的積層體10')的剖面圖。於製造MLCC1時,首先準備作為基材的陶瓷生片(介電質生片)。此處,例如將作為介電質材料的陶瓷粉末、黏合劑與有機溶劑等混合,製備介電質層形成用糊。其次,藉由利用刮刀法等將所製備的糊以薄層狀供給至載片(carrier sheet)上,而準備多片未鍛燒的陶瓷生片20'。FIG. 1B is a cross-sectional view schematically showing an unfired laminated wafer 10 (unfired laminated body 10 ′). When manufacturing MLCC1, a ceramic green sheet (dielectric green sheet) is first prepared as a base material. Here, for example, a ceramic powder as a dielectric material, a binder, an organic solvent, and the like are mixed to prepare a dielectric layer forming paste. Next, a plurality of unfired ceramic green sheets 20 'are prepared by supplying the prepared paste in a thin layer onto a carrier sheet by a doctor blade method or the like.
其次,準備本文揭示的導電性糊。具體而言,至少準備導電性粉末(A)、介電質粉末(B)、黏合劑(C)及分散介質(D),將該些以規定的比例調配,以透過率變化速度成為0.003以下的方式進行攪拌並混合,藉此製備導電性糊。而且,將所製備的糊以成為規定的圖案且所需厚度(例如1 μm以下)的方式供給至所準備的陶瓷生片20'上,形成導電性糊塗佈層30'。本文揭示的導電性糊的分散穩定性得到顯著提高。因此,於MLCC的量產時,即便導電性糊塗佈層30'於陶瓷生片20'上的形成(印刷)連續且經過長時間,導電性糊的性狀亦穩定,因此亦可使印刷品質良好地穩定。Next, prepare the conductive paste disclosed herein. Specifically, at least the conductive powder (A), the dielectric powder (B), the binder (C), and the dispersion medium (D) are prepared, and these are blended at a predetermined ratio so that the transmission rate change rate becomes 0.003 or less. The conductive paste is prepared by stirring and mixing in the same manner. Then, the prepared paste is supplied onto the prepared ceramic green sheet 20 ′ so as to have a predetermined pattern and a desired thickness (for example, 1 μm or less) to form a conductive paste coating layer 30 ′. The dispersion stability of the conductive paste disclosed herein has been significantly improved. Therefore, in mass production of MLCC, even if the formation (printing) of the conductive paste coating layer 30 ′ on the ceramic green sheet 20 ′ is continuous and elapsed over a long period of time, the properties of the conductive paste are stable, so that the printing quality can be improved.地 stable.
將所準備的帶導電性糊塗佈層30'的陶瓷生片20'積層多片(例如,數百片~數千片)並壓接。所述積層壓接體視需要切斷成晶片形狀。藉此,可獲得未鍛燒的積層體10'。繼而,將製作的未鍛燒的積層體10'於適當的加熱條件(例如,含氮環境中約1000℃~1300℃左右的溫度)下鍛燒。藉此,將陶瓷生片20'與導電性糊塗佈層30'同時鍛燒。陶瓷生片20'被鍛燒而成為介電質層20。導電性糊塗佈層30'被鍛燒而成為內部電極層30。介電質層20與內部電極層30被一體地燒結,可獲得燒結體(積層晶片10)。再者,於所述鍛燒前,為了使黏合劑及分散介質等有機成分消失,亦可實施脫黏合劑處理(例如含氧環境中,於比鍛燒溫度低的溫度:例如約250℃~700℃的加熱處理)。其後,藉由於積層晶片10的側面塗佈外部電極材料並進行燒接,而形成外部電極40。藉此,可製造MLCC1。The prepared ceramic green sheet 20 'with the conductive paste coating layer 30' is laminated on a plurality of sheets (for example, hundreds to thousands) and pressure-bonded. The laminated body is cut into a wafer shape as necessary. Thereby, the unfired laminated body 10 'can be obtained. Next, the produced unfired laminated body 10 'is fired under appropriate heating conditions (for example, a temperature of about 1000 ° C to 1300 ° C in a nitrogen-containing environment). Thereby, the ceramic green sheet 20 'and the conductive paste coating layer 30' are simultaneously fired. The ceramic green sheet 20 ′ is fired to form the dielectric layer 20. The conductive paste coating layer 30 ′ is fired to become the internal electrode layer 30. The dielectric layer 20 and the internal electrode layer 30 are sintered integrally to obtain a sintered body (multilayer wafer 10). In addition, before the calcination, in order to eliminate organic components such as the binder and the dispersion medium, a de-binder treatment may be performed (for example, in an oxygen-containing environment, at a temperature lower than the calcination temperature: for example, about 250 ° C to 700 ° C heat treatment). Thereafter, the external electrode 40 is formed by applying an external electrode material to the side surface of the laminated wafer 10 and performing firing. Thereby, MLCC1 can be manufactured.
以下,對與本發明有關的若干實施例進行說明,但並未意圖將本發明限定為所述實施例所示者。Hereinafter, several embodiments related to the present invention will be described, but it is not intended to limit the present invention to those shown in the embodiments.
[導電性糊的製備]
(例1)
按照以下順序製備下述表1所示的調配A的例1的導電性糊。
即,首先(1)調配鎳粉末、有機溶劑及分散劑,使用無介質式高速分散裝置進行分散處理,藉此準備鎳漿料。
繼而,(2)調配鈦酸鋇粉末、有機溶劑及分散劑,利用介質式磨機進行分散處理,藉此準備鈦酸鋇漿料。[Preparation of conductive paste]
(example 1)
The conductive paste of Example 1 of Formulation A shown in Table 1 below was prepared in the following procedure.
That is, first, (1) nickel powder, an organic solvent, and a dispersant are prepared, and a dispersion process is performed using a mediumless high-speed dispersing device to prepare a nickel slurry.
Next, (2) prepare a barium titanate slurry by preparing a barium titanate powder, an organic solvent, and a dispersant, and performing a dispersion treatment using a media mill.
而且,(3)使用無介質式高速分散裝置使所準備的鎳漿料、鈦酸鋇漿料及分散劑分散、混合,藉此製成鎳.鈦酸鋇混合漿料。
其後,(4)於所述鎳.鈦酸鋇混合漿料中加入另外製備的媒液與有機溶劑,利用無介質式高速分散裝置混合,藉此獲得導電性糊。In addition, (3) disperse and mix the prepared nickel slurry, barium titanate slurry and dispersant using a medium-free high-speed dispersing device to produce nickel. Barium titanate mixed slurry.
Thereafter, (4) in said nickel. A separately prepared vehicle and organic solvent are added to the barium titanate mixed slurry, and mixed with a medium-free high-speed dispersing device to obtain a conductive paste.
再者,於糊的製備時,於調配A中,鎳粉末(Ni)使用平均粒徑為180 nm者,鈦酸鋇粉末(BT)使用平均粒徑為10 nm者,使鈦酸鋇粉末相對於鎳粉末的比例成為10質量%。再者,對於該些的鎳粉末及鈦酸鋇粉末未實施特別的表面處理等分散處理。另外,作為有機溶劑,使用二氫萜品醇,作為分散劑,使用羧酸系分散劑。關於媒液,使用依據常法將作為黏合劑的乙基纖維素與有機溶劑預先進行加熱混合而成者。Furthermore, in the preparation of the paste, in Formulation A, the average particle diameter of nickel powder (Ni) was 180 nm, and the average particle diameter of barium titanate powder (BT) was 10 nm. The proportion of nickel powder was 10% by mass. In addition, these nickel powders and barium titanate powders are not subjected to a dispersion treatment such as a special surface treatment. As the organic solvent, dihydroterpineol was used, and as the dispersant, a carboxylic acid-based dispersant was used. The vehicle was prepared by heating and mixing ethyl cellulose as an adhesive and an organic solvent according to a conventional method.
(例2~例4)
繼而,於例1的導電性糊的製備時,使(1)鎳漿料與(2)鈦酸鋇漿料的製備時的分散處理的強度(周速或轉速)變化,變更分散劑的比例,藉此使糊中的鎳粉末或鈦酸鋇粉末的分散態樣變化。而且,其他條件設為與例1相同,藉此獲得例2~例4的導電性糊。
其中,關於例1~例4的導電性糊,作為分散處理條件,使攪拌速度於約8 m/s~60 m/s的範圍內變化。(Examples 2 to 4)
Next, in the preparation of the conductive paste of Example 1, the intensity (peripheral speed or rotation speed) of the dispersion treatment during the preparation of (1) the nickel slurry and (2) the barium titanate slurry was changed, and the ratio of the dispersant was changed. Thus, the dispersion state of the nickel powder or barium titanate powder in the paste is changed. Further, other conditions were set to be the same as those of Example 1, thereby obtaining conductive pastes of Examples 2 to 4.
However, regarding the conductive pastes of Examples 1 to 4, the stirring speed was changed within a range of about 8 m / s to 60 m / s as a dispersion treatment condition.
(例5)
於例1的導電性糊的製備時,採用表1所示的調配B來代替調配A,分散處理條件及其他條件與例1相同,獲得例5的導電性糊。再者,調配B中,鎳粉末使用平均粒徑為300 nm者,鈦酸鋇粉末使用平均粒徑為50 nm者。為了增大所使用的粉體的粒徑,使鈦酸鋇粉末相對於鎳粉末的比例增加為15質量%,使分散劑量減少。(Example 5)
In the preparation of the conductive paste of Example 1, Formulation B shown in Table 1 was used instead of Formulation A. The dispersion treatment conditions and other conditions were the same as in Example 1, and a conductive paste of Example 5 was obtained. In Formulation B, a nickel powder having an average particle diameter of 300 nm was used, and a barium titanate powder having an average particle diameter of 50 nm was used. In order to increase the particle size of the powder used, the ratio of the barium titanate powder to the nickel powder was increased to 15% by mass, and the dispersing amount was reduced.
(例6)
於例4的導電性糊的製備時,採用表1所示的調配B來代替調配A,分散處理條件及其他條件與例4相同,獲得例6的導電性糊。
例5與例6的導電性糊的調配大致相同,但分散處理的條件分別對應於例1與例4而不同。(Example 6)
In the preparation of the conductive paste of Example 4, Formulation B shown in Table 1 was used instead of Formulation A. The dispersion treatment conditions and other conditions were the same as those of Example 4, and a conductive paste of Example 6 was obtained.
The blending of the conductive pastes of Example 5 and Example 6 is almost the same, but the conditions of the dispersion treatment differ according to Examples 1 and 4, respectively.
[表1]
表1
Table 1
[透過率變化速度的測定]
關於所準備的例1~例6的導電性糊,按照以下順序測定透過率變化速度。
首先,將各例的導電性糊稀釋為適於評價此種導電性糊的分散穩定性的濃度、即固體成分濃度10質量%。稀釋使用作為有機溶劑的二氫萜品醇。再者,於稀釋時,為了不產生所謂的溶劑衝擊(solvent shock),一面攪拌導電性糊一面利用滴定管滴加有機溶劑並混合。具體而言,於100 mL的燒杯中量取10 g導電性糊,使用小型攪拌機(使用6枚葉片,轉速約200 rpm),一面攪拌燒杯中的導電性糊,一面以約2 mL為單位、以約5秒為間隔添加有機溶劑。有機溶劑的添加量例如對於例1的導電性糊10 g而言為45 g。[Measurement of transmission rate change rate]
Regarding the prepared conductive pastes of Examples 1 to 6, the transmittance change rate was measured in the following procedure.
First, the conductive paste of each example was diluted to a concentration suitable for evaluating the dispersion stability of such a conductive paste, that is, the solid content concentration was 10% by mass. Dihydroterpineol was used as an organic solvent for dilution. In addition, during the dilution, in order not to cause so-called solvent shock, an organic solvent was added dropwise with a burette while stirring the conductive paste, and mixed. Specifically, measure 10 g of conductive paste in a 100 mL beaker, and use a small mixer (using 6 blades at a rotation speed of about 200 rpm), while stirring the conductive paste in the beaker, while using 2 mL as the unit, Organic solvents were added at intervals of about 5 seconds. The amount of the organic solvent added is, for example, 45 g for 10 g of the conductive paste of Example 1.
關於所準備的稀釋糊,使用分散穩定性分析裝置(LUM GmbH公司製造的路密非(LUMiFuge)),測定透過率特性。測定使用分析裝置用的聚醯胺製的角管狀的一次性樣本槽(sample cell)(槽代碼(cell code)3、LUM 2 mmPA、測定容量0.4 mL~0.5 mL、測定光路長度2 mm)。所述樣本槽構成為收容0.4 mL的試樣並供於測定,0.4 mL的試樣的上表面位於距總長82 mm的樣本槽的底部23 mm的地點。稀釋糊使用注射器並秤量0.4 mL,自槽的底部緩緩地填充於槽中後,加蓋並用於測定。About the prepared dilution paste, the transmittance characteristic was measured using the dispersion stability analyzer (LUMiFuge made by LUM GmbH). The measurement was performed using an angular rectangular disposable sample cell (cell code 3, LUM 2 mmPA, measurement volume 0.4 mL to 0.5 mL, and measurement optical path length 2 mm) made of polyamine for an analysis device. The sample tank is configured to receive a 0.4 mL sample for measurement, and the upper surface of the 0.4 mL sample is located at a position 23 mm from the bottom of the sample tank having a total length of 82 mm. The diluted paste was weighed with a syringe using a syringe and weighed 0.4 mL. After the bottom of the tank was slowly filled in the tank, it was capped and used for measurement.
樣本槽水平地(以使槽的長度方向與離心方向一致)設置於分散穩定性分析裝置的轉子上並開始測定。
所述分散穩定性分析裝置藉由使轉子旋轉而對收容在樣本槽中的漿料實施離心沈降處理,同時對漿料的液面及漿料中粒子的沈降狀態進行光學檢測,藉此可當場直接測定。再者,粒子沈降狀態的光學檢測是藉由如下方式實施:利用振盪近紅外雷射的線光源,以相對於樣本槽沿長邊方向平行的方式照射雷射光,利用電荷耦合元件(Charge-Coupled Device,CCD)線感測器檢測其透過光的強度。本實施形態中,於以離心狀態存在於距樣本槽的底部23 mm的範圍內的試樣中,以包含距漿料的液面19 mm的區域的方式進行透過光強度的測定。另外,本實施形態中,藉由於規定的測定期間、實時地獲取樣本槽的位置資訊與所述位置的透過率的曲線,可獲得透過率的時間曲線。測定條件如下所述。The sample cell is set horizontally (so that the longitudinal direction of the cell coincides with the centrifugal direction) on the rotor of the dispersion stability analysis device and measurement is started.
The dispersion stability analysis device performs a centrifugal sedimentation treatment on the slurry contained in the sample tank by rotating the rotor, and simultaneously performs an optical detection on the liquid surface of the slurry and the sedimentation state of particles in the slurry, thereby enabling the spot Direct measurement. Furthermore, the optical detection of the particle sedimentation state is performed by using a linear light source of an oscillating near-infrared laser to irradiate laser light in a manner parallel to the longitudinal direction of the sample slot, and using a charge-coupled element Device (CCD) line sensor detects the intensity of transmitted light. In the present embodiment, the transmitted light intensity is measured so as to include a region of 19 mm from the liquid surface of the slurry in a sample that exists in a range of 23 mm from the bottom of the sample tank in a centrifuge state. In addition, in this embodiment, a time curve of transmittance can be obtained by acquiring a curve of the position information of the sample slot and the transmittance of the position in real time during a predetermined measurement period. The measurement conditions are as follows.
測定溫度:25.0℃
透過率測定波長:865 nm
光源強度:1(標準)
轉速:4000 rpm
測定間隔:10秒
測定時間:6200秒(其中,分析對象為6000秒為止)Measurement temperature: 25.0 ℃
Transmittance measurement wavelength: 865 nm
Light source intensity: 1 (standard)
Speed: 4000 rpm
Measurement interval: 10 seconds Measurement time: 6200 seconds (of which the analysis target is 6000 seconds)
例如,如圖2(t0 )所示,收容於樣本槽中的漿料最初以均勻的濃度分散有粒子,透過率亦固定。然而,如(t1 )、(t2 )所示,伴隨著進行離心沈降,漿料中的粒子朝槽底面(旋轉半徑方向的外側)移動(沈降)。藉此,自旋轉半徑方向的內側起樣本槽的規定位置的漿料濃度緩緩降低,所述位置的漿料的透過率緩緩變高。所述測定中,可獲得橫貫樣本槽的總測定長度的透過率分佈的時間變化曲線。For example, as shown in FIG. 2 (t 0 ), the slurry contained in the sample tank is initially dispersed with particles at a uniform concentration, and the transmittance is also fixed. However, as shown in (t 1 ) and (t 2 ), with the centrifugal sedimentation, the particles in the slurry move (sediment) toward the bottom of the tank (outer side in the direction of the radius of rotation). Thereby, the slurry concentration in the predetermined position of the sample tank gradually decreases from the inner side in the radial direction of rotation, and the transmittance of the slurry in the position gradually increases. In the measurement, a time change curve of the transmittance distribution across the total measurement length of the sample tank can be obtained.
因此,如圖3(a)所示,針對樣片槽的規定的測定區域對透過率(光透過率)進行積分,例如如(b)所示,將繪製其積分透過率與測定時間的關係時的傾斜度定義為「透過率變化速度」。粒子的沈降於離心沈降處理的最開始穩定地進行,但於粒子到達槽底面時不再進行而成為飽和狀態。本文揭示的技術中,如(c)所示,關於此種糊,將可認為粒子的沈降大致穩定地進行的0秒~6000秒為止的測定期間中的積分透過率(T)的每單位時間的變化量(ΔT/Δt)作為「透過率變化速度」而採用。關於透過率變化速度,值越大表示沈降越快、分散穩定性越差,值越小表示沈降越慢、分散穩定性越良好。另外,本實施形態中,關於樣本槽的距試樣上表面(液面)19 mm的區域,計算出透過率變化速度。據此,將關於各導電性糊計算出透過率變化速度的結果示於下述表2中。再者,透過率的測定中使用的光(此處為雷射光)的波長並不限制為所述例。Therefore, as shown in FIG. 3 (a), transmittance (light transmittance) is integrated for a predetermined measurement area of the sample slot. For example, as shown in (b), the relationship between the integrated transmittance and the measurement time is plotted. Is defined as the "transmittance change rate". The sedimentation of the particles is performed steadily at the beginning of the centrifugal sedimentation treatment, but when the particles reach the bottom surface of the tank, it does not proceed and becomes saturated. In the technique disclosed herein, as shown in (c), with respect to this paste, the sedimentation of particles can be considered to be performed approximately stably, and the unit transmittance (T) per unit time during the measurement period from 0 to 6000 seconds is considered to be substantially stable. The amount of change (ΔT / Δt) is adopted as the "transmittance change rate". Regarding the rate of change in transmittance, a larger value indicates faster sedimentation and worse dispersion stability, and a smaller value indicates slower sedimentation and better dispersion stability. In addition, in the present embodiment, the rate of change in transmittance is calculated for the area of the sample groove 19 mm from the upper surface (liquid surface) of the sample. Accordingly, the results of calculating the rate of change in transmittance for each conductive paste are shown in Table 2 below. The wavelength of light (here, laser light) used for the measurement of transmittance is not limited to the above-mentioned example.
[燒結性的評價]
繼而,為了確認所準備的例1~例6的導電性糊中的粒子的分散狀態對燒結性造成的影響,製作各導電性糊導電性膜,進行燒結性的評價。
首先,藉由膜敷料器以膜厚250 μm將各例的導電性糊約3 g塗佈於聚對苯二甲酸乙二酯(polyethylene terephthalate,PET)製膜上。其後,利用溫風乾燥機,將設定溫度設為100℃、乾燥時間設為15分鐘而進行處理,藉此獲得乾燥塗膜。繼而,將乾燥塗膜自PET製膜剝離,於N2
環境中以升溫速度200℃/h加熱,於到達溫度600℃下保持20分鐘,藉此進行脫黏合劑處理。而且,接著於(N2
+1%H2
)環境中,以升溫速度200℃/h加熱,於到達溫度1200℃下保持10分鐘,藉此進行正式鍛燒,而獲得導電性膜。[Evaluation of Sinterability]
Next, in order to confirm the influence of the dispersion state of the particles in the prepared conductive pastes of Examples 1 to 6 on the sinterability, each conductive paste conductive film was produced and evaluated for sinterability.
First, about 3 g of the conductive paste of each example was coated on a polyethylene terephthalate (PET) film with a film applicator at a film thickness of 250 μm. Thereafter, a dry coating film was obtained by processing with a warm air dryer at a set temperature of 100 ° C. and a drying time of 15 minutes. Then, the dried coating film was peeled from the PET film, and heated in a N 2 environment at a heating rate of 200 ° C./h, and maintained at a reaching temperature of 600 ° C. for 20 minutes, thereby performing a debinding treatment. Then, in a (N 2 + 1% H 2 ) environment, heating was performed at a temperature increase rate of 200 ° C./h, and the temperature was maintained at 1200 ° C. for 10 minutes, thereby subjecting it to formal firing to obtain a conductive film.
使用掃描式電子顯微鏡(Scanning Electron Microscope:SEM)觀察鍛燒後的導電性膜的表面(與PET製膜未接觸之側的表面),測定鍛燒後的鎳粒子與鈦酸鋇粒子的燒結後平均粒徑。
具體而言,首先對鍛燒後的導電性膜的表面進行約30秒Au蒸鍍,藉此準備SEM觀察用試樣。而且,基於將觀察倍率設定為10000倍而獲得的SEM圖像,求出鎳粒子及鈦酸鋇粒子的面積圓相當徑(Heywood徑)。關於圓相當徑,藉由分別選出可自約4視野~6視野的SEM圖像中識別粒界的約70個鎳粒子及鈦酸鋇粒子,並使用圖像處理軟體設定各粒子的輪廓而計算出圓相當徑(參照圖6)。而且,將針對約70個各粒子而獲得的面積圓相當徑的個數基準的粒度分佈中的累積50%粒徑(D50
)設為所述導電性膜中的鎳粒子或鈦酸鋇粒子的平均粒徑。另外,關於個數基準的粒度分佈中的累積90%粒徑(D90
),亦同樣地計算出,將該些結果示於以下的表3與表4中。A scanning electron microscope (Scanning Electron Microscope: SEM) was used to observe the surface of the conductive film (the surface on the side not in contact with the PET film) after calcination, and measure the calcined nickel particles and barium titanate particles after sintering. The average particle size.
Specifically, first, the surface of the fired conductive film was subjected to Au vapor deposition for about 30 seconds to prepare a sample for SEM observation. Then, based on the SEM image obtained by setting the observation magnification to 10,000 times, the area circle equivalent diameter (Heywood diameter) of the nickel particles and the barium titanate particles was determined. The circle equivalent diameter is calculated by selecting approximately 70 nickel particles and barium titanate particles that can recognize grain boundaries from SEM images of about 4 to 6 fields of view, and setting the contour of each particle using image processing software. The diameter of the circle is quite large (see Figure 6). In addition, the cumulative 50% particle diameter (D 50 ) in the particle size distribution based on the number-of-area-circle-equivalent-diameter-based particle size distribution obtained for about 70 particles was defined as nickel particles or barium titanate particles in the conductive film. Average particle size. The cumulative 90% particle size (D 90 ) in the number-based particle size distribution was calculated in the same manner, and the results are shown in Tables 3 and 4 below.
另外,為了參考,於圖5中示出使用例1及例4的導電性糊而製作的導電性膜的SEM觀察圖像(20000倍)。除此以外,於圖6中,關於例4的導電性膜的SEM觀察圖像(10000倍),為了測定鎳粒子(Ni)及鈦酸鋇粒子(BT)的平均粒徑,一併示出描繪粒子的輪廓的情況。In addition, for reference, an SEM observation image (20,000 times) of a conductive film produced using the conductive pastes of Examples 1 and 4 is shown in FIG. 5. In addition, in FIG. 6, the SEM observation image (10,000 times) of the conductive film of Example 4 is shown together to measure the average particle diameters of the nickel particles (Ni) and barium titanate particles (BT). A case where the outline of a particle is drawn.
[表2]
表2
Table 2
[表3]
表3
table 3
如表2所示,可知即便所使用的原料相同,亦可藉由使其製備方法發生變化而使所獲得的導電性糊的透過率變化速度明顯不同。本實施形態中,使例1~例4的鎳漿料及鈦酸鋇漿料的攪拌強度於8 m/s~60 m/s的範圍內分別發生變化。同樣地,亦使例5~例6的鎳漿料及鈦酸鋇漿料的攪拌強度於8 m/s~60 m/s的範圍內分別發生變化。結果可知,例如關於例1及例5的導電性糊,透過率變化速度變小且分散穩定性提高,關於例4及例6的導電性糊,透過率變化速度變大且分散穩定性變低。如此,認為於所獲得的導電性糊中的Ni粒子與BT粒子的分散上體及分散穩定性變化時,該些粒子的分散穩定性可藉由使用透過率變化速度作為指標而較佳地顯現(數值化)。As shown in Table 2, it can be seen that even if the same raw materials are used, the rate of change in transmittance of the obtained conductive paste can be significantly different by changing the preparation method. In this embodiment, the stirring strength of the nickel slurry and the barium titanate slurry of Examples 1 to 4 is changed within a range of 8 m / s to 60 m / s, respectively. Similarly, the stirring strength of the nickel slurry and the barium titanate slurry of Examples 5 to 6 was also changed within the range of 8 m / s to 60 m / s. As a result, it was found that, for the conductive pastes of Examples 1 and 5, the transmittance change rate becomes smaller and the dispersion stability is improved, and for the conductive pastes of Examples 4 and 6, the transmittance change rate becomes larger and the dispersion stability becomes lower. . In this way, when the dispersion upper body and dispersion stability of Ni particles and BT particles in the obtained conductive paste are changed, it is considered that the dispersion stability of these particles can be better exhibited by using the rate of change in transmittance as an index. (Numerical).
另一方面,如表2、表3所示可知,越為透過率變化速度小的糊,鍛燒後所獲得的導體膜中的Ni粒子及BT粒子的D50 及D90 越小,例如如圖5的例1所示,鍛燒所引起的各粒子的晶粒成長得到抑制。另外可知,越為透過率變化速度大的糊,鍛燒後所獲得的導體膜中的Ni粒子及BT粒子的D50 及D90 越大,例如如圖5的例4所示,鍛燒所引起的晶粒成長無法得到抑制。據此可知,關於本文揭示的導電性糊的透過率變化速度亦可作為預先掌握所述導電性糊的鍛燒時的晶粒成長行為的指標而較佳地使用。On the other hand, as shown in Tables 2 and 3, it can be seen that the D 50 and D 90 of the Ni particles and the BT particles in the conductor film obtained after calcination are smaller as the paste having a lower change rate in transmittance is smaller, for example, as As shown in Example 1 of FIG. 5, grain growth of each particle due to calcination is suppressed. In addition, it can be seen that the D 50 and D 90 of the Ni particles and BT particles in the conductor film obtained after calcination are larger as the paste having a larger transmission rate change rate. For example, as shown in Example 4 of FIG. The induced grain growth cannot be suppressed. It can be seen from this that the rate of change in transmittance of the conductive paste disclosed herein can also be used as an index for grasping in advance the grain growth behavior of the conductive paste during calcination, and is preferably used.
更具體而言,如圖4(a)所示,例1、例5的導體膜中的Ni粒子的粒度分佈的最大頻率高且極其尖銳。關於例1及例5,可知儘管作為原料使用的Ni粉末的平均粒徑為180 nm與300 nm而不同,但燒結後的Ni粒子的粒度分佈大致為相同形狀,若透過率變化速度小,則Ni粒子的成長均以高水準得到抑制。關於例2的導體膜的Ni粒子的粒度分佈,最大頻率稍低的峰值寬度維持與例1同樣的寬度。相對於此,例如關於例3及例4的導電膜中的Ni粒子的粒度分佈,可知粗大粒子的存在增加而變寬,至於例4,粗大粒子的數量大幅增加,在粒度分佈中形成左肩(第二峰值)。可知相較於例4的Ni粒子而言,例6的導電膜中的Ni粒子藉由燒結顯著地進行晶粒成長。另外,如圖4(b)所示可知,由於BT粒子比Ni粒子更微細,因此雖然鍛燒所引起的晶粒成長變得顯著,但如表3所示,顯示出與Ni粒子大致相同的行為。More specifically, as shown in FIG. 4 (a), the maximum frequency of the particle size distribution of the Ni particles in the conductor films of Examples 1 and 5 is high and extremely sharp. Regarding Examples 1 and 5, although the average particle size of the Ni powder used as the raw material is different between 180 nm and 300 nm, the particle size distribution of the sintered Ni particles is approximately the same shape. If the rate of change in transmittance is small, The growth of Ni particles is suppressed at a high level. Regarding the particle size distribution of the Ni particles of the conductor film of Example 2, the peak width with a slightly lower maximum frequency maintained the same width as that of Example 1. In contrast, for example, regarding the particle size distribution of the Ni particles in the conductive films of Examples 3 and 4, it can be seen that the presence of coarse particles increases and widens. As for Example 4, the number of coarse particles increased significantly, forming a left shoulder in the particle size distribution ( Second peak). It can be seen that, compared with the Ni particles of Example 4, the Ni particles in the conductive film of Example 6 undergo significant grain growth by sintering. In addition, as shown in FIG. 4 (b), the BT particles are finer than the Ni particles. Although the grain growth caused by the calcination becomes significant, as shown in Table 3, it shows that they are approximately the same as the Ni particles. behavior.
據此可知,關於使用透過率變化速度小的例1的導電性糊而形成的導體膜,原料粒子的鍛燒時的晶粒成長得到抑制,厚度更薄,表面平坦,可形成均勻的導體膜。詳情雖不明確,例如關於例1、例5的導電性糊,認為例如Ni粒子及微細的BT粒子不凝聚,即便於糊狀態下,在塗膜形成時亦可於Ni粒子彼此間較佳地配置BT粒子。而且,認為藉此可較佳地抑制鍛燒時的Ni粒子的燒結及晶粒生長。相對於此,關於透過率變化速度大的例4、例6的導電性糊,認為例如微細的BT粒子凝聚等,無法較佳地抑制Ni粒子彼此的接觸。認為藉此於鍛燒時Ni粒子及BT粒子分別顯著地進行晶粒成長。例如,若導電性糊的透過率變化速度為0.003以下,則可以說糊中的粒子的分散穩定性高,可獲得由更微細的燒結粒子構成的導體膜。另外,認為若導電性糊的透過率變化速度高於0.003,則糊中的粒子的分散穩定性低,於形成塗膜時同種粒子彼此以更高的頻率接觸,藉由鍛燒而容易地進行晶粒成長。From this, it can be seen that the conductor film formed using the conductive paste of Example 1 having a small transmittance change rate can suppress the grain growth during the calcination of the raw material particles, the thickness is thinner, the surface is flat, and a uniform conductor film can be formed. . Although the details are not clear, for example, regarding the conductive pastes of Examples 1 and 5, it is considered that, for example, Ni particles and fine BT particles do not agglomerate, and even in a paste state, Ni particles can be preferably formed between the Ni particles during coating film formation. Configure BT particles. In addition, it is considered that the sintering and grain growth of the Ni particles at the time of calcination can be better suppressed by this. On the other hand, regarding the conductive pastes of Examples 4 and 6 in which the rate of change of transmittance is large, it is considered that, for example, the fine BT particles are agglomerated, and the contact between the Ni particles cannot be satisfactorily suppressed. It is considered that the Ni grains and BT grains each significantly undergo grain growth during the calcination. For example, if the rate of change of the transmittance of the conductive paste is 0.003 or less, it can be said that the dispersion stability of the particles in the paste is high, and a conductor film composed of finer sintered particles can be obtained. In addition, if the rate of change of the transmittance of the conductive paste is higher than 0.003, the dispersion stability of the particles in the paste is low, and the same kind of particles contact each other at a higher frequency during the formation of the coating film, and it is easily carried out by firing Grain growth.
藉由使用本文揭示的導電性糊,可抑制導電性粒子的異常晶粒成長而形成導體膜。藉此,例如於MLCC的製造中可抑制內部電極層的膨脹或導電性粒子所引起的經薄層化的介電質層的刺破而製造耐電壓及可靠性高的MLCC。
以上,詳細地說明了本發明,但該些僅為例示,本發明可於不脫離其主旨的範圍內施加各種變更。By using the conductive paste disclosed herein, abnormal grain growth of conductive particles can be suppressed to form a conductive film. This makes it possible, for example, to suppress expansion of the internal electrode layer or puncture of the thinned dielectric layer caused by conductive particles in the production of the MLCC, thereby producing an MLCC with high withstand voltage and reliability.
The present invention has been described in detail above, but these are merely examples, and the present invention can be modified in various ways without departing from the spirit thereof.
1‧‧‧積層陶瓷電容器(MLCC) 1‧‧‧Multilayer Ceramic Capacitors (MLCC)
10‧‧‧積層晶片 10‧‧‧Laminated Wafer
10'‧‧‧未鍛燒的積層體 10'‧‧‧Unfired laminate
20‧‧‧介電質層 20‧‧‧ Dielectric layer
20'‧‧‧陶瓷生片 20'‧‧‧ceramic green sheet
30‧‧‧內部電極層 30‧‧‧Internal electrode layer
30'‧‧‧導電性糊塗佈層 30'‧‧‧ conductive paste coating layer
40‧‧‧外部電極 40‧‧‧External electrode
圖1A為概略性地說明MLCC的構成的剖面示意圖。FIG. 1A is a schematic cross-sectional view illustrating the structure of an MLCC.
圖1B為概略性地說明未鍛燒的MLCC本體的構成的剖面示意圖。 FIG. 1B is a schematic cross-sectional view schematically illustrating the structure of an uncalcined MLCC body.
圖2的(t0 )~圖2的(t2 )是說明對導電性糊實施離心沈降處理時的透過率分佈與其時間變化的情況的圖。(T 0 ) to (t 2 ) of FIG. 2 are diagrams illustrating a change in transmittance distribution and a change in time when the conductive paste is subjected to a centrifugal sedimentation treatment.
圖3的(a)是說明導電性糊的透過率分佈的時間變化的圖,圖3的(b)是說明積分透過率的時間變化的圖,圖3的(c)是說明透過率變化速度的圖。 (A) is a figure explaining the time change of the transmittance distribution of a conductive paste, (b) is a figure explaining the time change of an integrated transmittance, and (c) is a figure explaining the change rate of the transmittance Illustration.
圖4是於對各例的導電性糊進行鍛燒的導電膜中,基於掃描式電子顯微鏡(Scanning Electron Microscope,SEM)觀察而測量的(a)鎳粒子與(b)鈦酸鋇粒子的粒度分佈。 FIG. 4 is the particle size of (a) nickel particles and (b) barium titanate particles measured in a conductive film obtained by calcining the conductive paste of each example based on a scanning electron microscope (SEM) observation. distributed.
圖5是例1及例4的導電膜的表面的SEM觀察圖像。 FIG. 5 is an SEM observation image of the surfaces of the conductive films of Examples 1 and 4. FIG.
圖6是說明例4的導電膜中鎳(Ni)粒子與鈦酸鋇(BT)粒子的粒徑測定的情況的圖。 FIG. 6 is a diagram illustrating the measurement of particle diameters of nickel (Ni) particles and barium titanate (BT) particles in the conductive film of Example 4. FIG.
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WO2013157516A1 (en) * | 2012-04-19 | 2013-10-24 | 株式会社村田製作所 | Conductive paste, laminated ceramic electronic component and method for manufacturing laminated ceramic electronic component |
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CN113948236B (en) * | 2021-12-21 | 2022-03-29 | 西安宏星电子浆料科技股份有限公司 | Thick-film silver-palladium conductor paste for wear-resistant high-precision oil level sensor |
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