KR20000001699A - NiCuZn FERRITE PASTE - Google Patents

Abstract

PURPOSE: NiCuZn ferrite paste is proper to a magnetic layer in manufacturing a hybrid chip component, and has a superior smoothing and a dispersion stability. CONSTITUTION: NiCuZn ferrite paste includes a co-polymer of polyvinylbutyral-vinylalcohol-vinylacetate as a binder component and NiCuZn ferrite indicated as a chemical equation 1(NixCuyZnzO * Fe2O3), where x=0.1¯0.55, y=0.15¯0.3, z=0.3¯0.75, x+y+z=1. Accordingly, the NiCuZn ferrite paste minutely accumulates a green sheet, makes a smaller chip, and does not need a punching machine.

Description

ＮｉＣｕＺｎ ferrite paste

The present invention relates to a NiCuZn ferrite paste, and more specifically, the green sheet is precisely laminated by containing polyvinyl butyral-vinyl alcohol-vinylacetate copolymer as a binder component in the NiCuZn ferrite powder represented by Formula 1 below. Not only can you manufacture small chips, you do not have to buy expensive punching machines, and all of the main lamination processes can be done by screen printing, which saves not only your initial investment but also your maintenance costs. The present invention relates to a NiCuZn ferrite paste suitable for the formation of a magnetic layer in the manufacture of a hybrid chip component in which a transformer or a resistor or a condenser is combined, and having excellent smoothness and dispersion stability.

Formula 1

Ni _x Cu _y Zn _z OFe ₂ O ₃

In Formula 1, x is 0.1 to 0.55, y is 0.15 to 0.3, z is 0.3 to 0.75, and x + y + z = 1.

Since ferrite paste is a complex oxide, it is very difficult to have dispersion stability, and thus, a magnetic slurry has been mostly manufactured, and then a green sheet is manufactured using a Dr. blade and used for magnetic lamination. Japanese Patent Application Laid-Open Nos. 56-120114, 56-144512, 1-105516, 1-222419, 2-2-144906, 3-3-278506, 4-180609; U.S. Patent Nos. 4,322,698, 4,731,297]. The lamination method using the green sheet is difficult to align the upper and lower inner conductors due to poor lamination accuracy, and it causes disconnection or connection at the lamination interface, which causes the coil to lose its function, and causes problems in miniaturization. have.

Another method is to make a green sheet, and process a via hole for connecting internal conductors with a punching machine, and then laminate it. [Japanese Patent Laid-Open No. 58-10810, No. 62-61305, P. 2-256208; U.S. Patent No. 5,302,932], but this method also maintains a gap of 2 mm or less (adjusted according to the size of the chip) and is not easy to process a φ0.2 mm circular hole (via hole), Due to the deformation of the sheet, it is very difficult to precisely stack the magnetic material, so that the alignment of the inner conductors is also difficult to be constant.

If the above two methods are used, it is difficult to reduce the thickness of the green sheet to 50 to 100 μm or less in terms of handling, thereby limiting the performance of the chip, and lowering the production yield. For this reason, the process of making and using the green sheet is easier to automate than the process using the paste, which affects productivity. In order to improve such a process problem, a method of using a magnetic paste (Japanese Patent Laid-Open No. 2-165608) is disclosed, but details of the preparation of the paste are not mentioned.

Recently, the printing technology is a technique of laminating a magnetic layer like a lamination inductor, and is rapidly advanced in the direction of making and using magnetic paste.

There are two methods for laminating a magnetic layer, a method of preparing a paste using a magnetic oxide and a method of preparing a paste using an organometallic compound. Among them, as a method of using a magnetic oxide, ethyl cellulose is used as a binder and terpineol is used as a solvent to prepare a paste [Atsuyuki Nakano, Hiroshi Momoi, and Takeshi Nomura, "Effect. of Ag on the Microstructure of the Low Temperature Sintered NiCuZn Ferrite ", powder and powder metallurgy, Vol. 39, No. 8, pp612-617 (1992.8)], and using a polybutyral as a binder and a solvent A method of producing NiCuZn ferrite paste using ethyl cellusolve and using two surfactants as a dispersion stabilizer is disclosed (Japanese Patent Laid-Open No. 8-268720). However, this does not specify the molecular weight distribution or the amount of use range of the polymer used as the binder of the paste has many problems in making the paste by using this method. In particular, the paste using ethyl cellulose (terpenol) and terpineol (terpineol) has a disadvantage in that the dispersing property is poor, the amount of the solvent is required more, the printing property is not good and the sheet ductility is not easy to break.

In addition, the method of preparing the paste by combining the organometallic compounds (European Patent 0,743, 284 A1) is not economically preferable because the production cost of the paste is higher than that of the metal oxide due to the use of the organometallic compound.

Therefore, the present inventors use NiCuZn ferrite represented by Chemical Formula 1 as a magnetic oxide, and NiCuZn ferrite paste containing a polyvinyl butyral-vinyl alcohol-vinylacetate copolymer as a binder component is a surface mount such as a chip inductor and a chip transformer. The present invention has been completed by knowing that it is very useful for stacking magnetic materials in printing processes used for manufacturing hybrid chips as well as mold parts.

Therefore, in the present invention, the green sheet can be precisely stacked to manufacture smaller chips, and there is no need to purchase an expensive punching machine, and all the main lamination processes can be performed by screen printing. It has the advantage of saving, and is suitable for the formation of a magnetic layer in the manufacture of hybrid chip components in which stacked chip inductors, transformers, or resistors or condensers are combined, and has excellent smoothness and dispersion. It is an object to provide a NiCuZn ferrite paste having stability.

The present invention is characterized by a NiCuZn ferrite paste in which a NiCuZn ferrite represented by the following formula (1) and a polyvinyl butyral-vinyl alcohol-vinylacetate copolymer are contained as a binder component.

Formula 1

Ni _x Cu _y Zn _z OFe ₂ O ₃

In Formula 1, x is 0.1 to 0.55, y is 0.15 to 0.3, z is 0.3 to 0.75, and x + y + z = 1.

The present invention will be described in more detail as follows.

The present invention uses a polyvinyl butyral-vinyl alcohol-vinylacetate copolymer as a binder component in NiCuZn ferrite powder, and contains butyl carbitol as a solvent, thereby providing soft magnetic properties necessary for using a screen printing method for precise pattern printing and lamination. It relates to a paste of oxide.

In the present invention, a metal oxide is used instead of a conventional organic metal oxide as a magnetic oxide, which is a powder of NiCuZn ferrite (spinel type crystal) represented by Chemical Formula 1. NiCuZn ferrite powder represented by Chemical Formula 1 is a soft magnetic material used to manufacture chip inductors or chip transformers, and is a main oxide used to make monolithic chips made by firing together with internal conductors for low temperature firing. In the case of preparing the paste using the same, the paste may be easily prepared by using a cheaper raw material and a general ceramic process than the paste prepared using a conventional organometallic compound. The NiCuZn ferrite powder constituting the magnetic material of the paste is characterized by different concentrations of Ni, Cu, Zn and Fe oxides. Indicates.

In general, the surface of the metal oxide is mostly hydrophilic, and if the particle size is small, the surface activity is very large, making the paste is not easy, so the storage is also poor. In order to make such a magnetic paste, the selection of a binder and a solvent is very important. In particular, the screen printing technique is very important for precise patterning and lamination, and in order to introduce such a technique, a paste having proper characteristics for screen printing must be prepared.

The paste solids prepared in the present invention are prepared as a low magnetic solvent and a polymer used as a soft magnetic material NiCuZn ferrite and a binder. After printing, solids remain due to the volatilization of the solvent. After sintering, only the soft magnetic material NiCuZn ferrite remains. Therefore, when the amount of the polymer used as the binder is large, it is difficult to completely remove the organic matter during sintering and to reduce the amount of the polymer to the minimum in order to improve the electromagnetic properties. Accordingly, the viscosity characteristic of the paste is determined by the amount of the binder polymer and the solvent. Since the surface of NiCuZn ferrite, a soft magnetic material, is mostly covered with oxygen or partly has an active metal surface, it is easy to bond with water and difficult to bond with organic matter. Accordingly, the polymer used as a binder is a polymer having a hydroxyl group, a carbonyl group, a carboxyl group, or an amine group, which is easily hydrogen-bonded with an oxygen atom of a metal oxide, and a polymer compound which is not bonded or added to a halogen compound, a sulfur compound, and a phosphate compound It must be well dissolved in organic solvents and have rheological viscous properties, and must be able to maintain the properties of pastes made by being a stable compound without being affected by active metals even during long-term storage. In order to maintain these characteristics, the present invention uses a polyvinyl butyral-vinyl alcohol-vinylacetate copolymer as the binder component. In this case, the polyvinyl butyral-vinyl alcohol-vinylacetate copolymer may be selected from those having a molecular weight distribution in the range of 5,000 to 120,000, and if necessary, a mixture of those having different molecular weight distributions may be selected and used. For example, a copolymer having a low molecular weight of 5,000 to 80,000, a medium molecular weight of 70,000 to 100,000 and a high molecular weight distribution of 90,000 to 120,000 is used. At this time, when mixing and using copolymers from which molecular weight distribution differs, it is preferable that the usage-amount is used within the range of 25-50 weight% of each copolymer. If the use range of the copolymer is out of the above range, there is a problem not only to control the properties of the paste but also to perform precise printing. When using a mixture of copolymers having different molecular weight distribution as described above has the advantage that the properties of the paste can be easily adjusted.

Such polyvinyl butyral-vinyl alcohol-vinylacetate copolymer is contained in 3 to 6 parts by weight, preferably 3.5 to 4.5 parts by weight, based on 100 parts by weight of NiCuZn ferrite powder, if the content is less than 3 parts by weight. Poor printability due to poor viscosity characteristics, and also easy to break due to poor bonding strength of NiCuZn ferrite powder after drying, and when it exceeds 6 parts by weight, degreasing is difficult during firing, resulting in long degreasing time or carbon remaining due to poor degreasing. Make it fall.

In order to manufacture the ferrite paste of the present invention, the above-mentioned NiCuZn ferrite powder and the polyvinyl butyral-vinyl alcohol-vinylacetate copolymer are mixed at an appropriate ratio, and a solvent is added thereto to prepare a paste. At this time, the solvent is a polymer that is well dissolved and low volatility used as a binder, all commonly used solvents such as terpinol, methyl cell solution, cell solution, butyl cell solution, methyl carbitol, carbitol can be used, Preferably, butyl carbitol is used. Such a solvent is contained in an amount of 25 to 30 parts by weight based on 100 parts by weight of NiCuZn ferrite powder to prepare a paste. If the content of the solvent is out of the above range it is difficult to prepare the paste to be desired in the present invention.

As compared with the NiCuZn paste disclosed in Japanese Patent Application Laid-open No. Hei 8-268720, the NiCuZn ferrite paste of the present invention has a reference viscosity and a screen viscosity index (SVI :) for the amount of solvent and the amount of solvent used. Screen viscosity index), viscosity properties of pseudo plastic exponent index m [Ralph E. Trease and Raymond L. Dietz, "Rheology of Pastes in Think-Film Printing", Solid State Technology, pp 33-43 (Jan 1972)] and a comparative study of the characteristics printed on a 325 mesh silk screen with a pattern of 0.2 mm in line width. Precise printing allows ultimately mass production of small and precise chip inductors or chip transformers with high yield and automated processes It can be seen.

Although this invention is demonstrated in detail based on an Example, this invention is not limited to an Example.

Example 1

NiCuZn ferrite powder (Ni _0.15 Cu _0.25 Zn _0.6 O · Fe ₂ O ₃ ; Specific surface area 10 ㎡ / g) after adding 1.5 g of polyvinyl butyral resin (Japan Waco; polymerization degree 700) to 7 g of butyl carbitol to completely dissolve the binder. 37.5g was added and mixed well with a reagent spoon on a watch plate. This was transferred to a 3-roll mill and dispersion operation was performed. NiCuZn ferrite paste was prepared by milling 3 g of butyl carbitol in a 3-roll mill to ensure complete dispersion.

Example 2

NiCuZn ferrite powder (Ni _0.15 Cu _0.25 Zn _0.6 O · Fe ₂ O ₃ ; Specific surface area 10 ㎡ / g) after adding 1.5 g of polyvinyl butyral resin (Japan Waco; polymerization degree 700) to 7 g of butyl carbitol to completely dissolve the binder. 37.5g was added and mixed well with a reagent spoon on a watch plate. This was transferred to a 3-roll mill and dispersion operation was performed. NiCuZn ferrite paste was prepared by milling the addition of 3.5 g of butyl carbitol in a 3-roll mill to ensure complete dispersion.

Example 3

Polyvinyl butyral resin (Waco Japan; degree of polymerization 700) was completely dissolved into 1.5g of the butyl carbitol 7g NiCuZn ferrite powder _{(Ni 0.15 Cu 0.25 Zn 0.6 O} · Fe 2 O 3; a specific surface area of 10 ㎡ / g) 37.5g Was added and mixed well with a reagent spoon on a watch plate. This was transferred to a 3-roll mill and dispersion operation was performed. NiCuZn ferrite paste was prepared by milling the addition of 3.75 g of butyl carbitol in a 3-roll mill to ensure complete dispersion.

Comparative Example 1

1.5 g of ethyl cellulose (Japanese Waco; 100 cps) was added to 7 g of terpinol to completely dissolve. As a binder, 37.5 g of NiCuZn ferrite powder (Ni _0.15 Cu _0.25 Zn _0.6 O.Fe ₂ O ₃ ; specific surface area 10 m 2 / g) was added thereto. Mix well with reagent spoons on a watch plate. This was transferred to a 3-roll mill and dispersion operation was performed. NiCuZn ferrite paste was prepared by milling to add 4 g of terpinol in a 3-roll mill to ensure complete dispersion.

Experimental Example 1

The NiCuZn ferrite pastes prepared in Examples 1 to 3 and Comparative Example 1 were screened by measuring the viscosity and relaxation viscosity with a cone and plate type viscometer (Brookfield Co.). Calculate viscose index (SVI) and pseudo plastic coefficient index m and perform screen printing to measure printability, leveling and precision of printed lines, and the results are shown in Table 1 below. Indicated.

The printability was measured by comparing the best and worst of the separation between the silk screen and the printing matrix in four stages during silk screen printing, and the leveling was performed by observing the printed surface of the paste under a microscope under the microscope. The traces left and disappeared were measured in four stages, and the line precision was measured by a microscope after printing, and the linearity of the lines was measured in four stages.

Viscosity and relaxation viscosity were calculated by the following equation 1, the screen viscose index (SVI) was calculated by the following equation (2).

In Equation 1, B is the viscosity at shear rate (1 / sec) 1, R is the shear stress (1 / sec) applied to the paste, and N, Y and m are measured by measuring the viscosity. It is the value obtained by calculation by the least squares method from the obtained value.

division Viscosity (mPa.s) SVI (m) result Screen (100s ^-1 ) Leveling (0.1s ^-1 ) Printability Leveling Line precision Example 1 30,040 7,254,800 241.5 (0.7943) ○ ◎ ○ Example 2 22,200 3,927,000 176.6 (0.749) ○ ○ ◎ Example 3 21,100 3,198,000 151.4 (0.7267) ◎ ◎ ◎ Comparative Example 1 27,110 1,537,000 56.7 (0.585) △ ○ × (Note) ◎: Very good ○: Good △: Normal ×: Bad

As shown in Table 1, NiCuZn ferrite paste prepared by using one polyvinyl butyral resin as a binder component in Examples 1 to 3 and using 27 to 30 parts by weight of a solvent based on 100 parts by weight of NiCuZn ferrite powder When silk screen printing was carried out using the present invention, it was found that printability, leveling, and line precision were excellent, whereas NiCuZn ferrite paste prepared using conventional ethyl cellulose as a binder component (Comparative Example 1) contained 30 wt. It can be seen that the characteristics are deteriorated despite the minor use.

Examples 4 to 13

As shown in Table 2 below, 1.5 g of a mixture of polyvinyl butyral-vinyl alcohol-vinylacetate copolymer (Aldrich Co., USA) having different molecular weight distribution was completely dissolved in 8 g of butyl carbitol, and then NiCuZn ferrite powder (Ni Mix well with 37.5 g of _0.15 Cu _0.25 Zn _0.6 O.Fe ₂ O ₃ ; specific surface area 10 m 2 / g) and add 2.75 g of butyl carbitol in a 3-roll mill to mill for complete dispersion to form a NiCuZn ferrite paste Prepared.

Experimental Example 2

The NiCuZn ferrite pastes prepared in Examples 4 to 13 were measured for viscosity in the same manner as in Experimental Example 1 and subjected to screen printing to measure printability, leveling degree, and precision of printed lines. Shown in

division Polyvinyl butyral-vinyl alcohol-vinylacetate copolymer (g) A B C Example 4 1.5 - - Example 5 - 1.5 - Example 6 - - 1.5 Example 7 0.5 0.5 0.5 Example 8 1.0 0.25 0.25 Example 9 0.25 1.0 0.25 Example 10 0.25 0.25 1.0 Example 11 0.75 0.75 - Example 12 - 0.75 0.75 Example 13 0.75 - 0.75 (Note) A: Molecular weight distribution in the range of 50,000 to 80,000 B: Molecular weight distribution in the range of 70,000 to 100,000 C: Molecular weight distribution in the range of 90,000 to 120,000

division Viscosity (mPa.s) SVI (m) result Screen (100s ^-1 ) Leveling (0.1s ^-1 ) Printability Leveling Line precision Example 4 31,870 2,603,000 101.7 (0.737) ◎ ○ ○ Example 5 56,490 6,047,000 107.0 (0.836) ○ ○ ◎ Example 6 37,390 3,650,000 107.6 (0.763) ○ ◎ ○ Example 7 21,950 4,829,000 220.0 (0.781) ◎ ◎ ○ Example 8 20,770 2,453,000 118.1 (0.791) ◎ ○ ○ Example 9 27,010 7,019,000 259.8 (0.805) ◎ ◎ ◎ Example 10 26,840 8,850,000 229.8 (0.839) ◎ ○ ◎ Example 11 19,590 2,526,000 129.0 (0.704) ◎ ◎ △ Example 12 28,870 5,886,000 203.9 (0.770) ○ ○ △ Example 13 20,830 1,753,000 184.2 (0.742) ○ △ ◎ (Note) ◎: Very good ○: Good △: Normal ×: Bad

The pastes prepared in Examples 4 to 6 use one as a binder component, and the pastes prepared in Examples 7 to 10 use three types as binder components, and Examples 11 to 13 use two kinds as binder components. Used. As shown in Table 3 above, when one is selected and used as the binder component, the viscosity is slightly higher than the others, but the printability, leveling, and line precision are similar, and when two kinds are selected as the binder components, The result is better than that of using one binder, and especially when three kinds of mixtures are used, the results are very excellent.

Example 14

NiCuZn ferrite paste was prepared in the same manner as in Example 3, using NiCuZn ferrite powder (Ni _0.1 Cu _0.2 Zn _0.7 OFe ₂ O ₃ ; specific surface area of 10.2 m 2 / g).

Example 15

NiCuZn ferrite paste was prepared in the same manner as in Example 4, using NiCuZn ferrite powder (Ni _0.45 Cu _0.2 Zn _0.35 OFe ₂ O ₃ ; specific surface area of 9.8 m 2 / g).

Example 16

NiCuZn ferrite paste was prepared in the same manner as in Example 6, using NiCuZn ferrite powder (Ni _0.1 Cu _0.15 Zn _0.75 OFe ₂ O ₃ ; specific surface area of 10.1 m 2 / g).

Example 17

NiCuZn ferrite paste was prepared in the same manner as in Example 8, using NiCuZn ferrite powder (Ni _0.55 Cu _0.15 Zn _0.3 OFe ₂ O ₃ ; specific surface area of 9.6 m 2 / g).

Example 18

NiCuZn ferrite paste was prepared in the same manner as in Example 9, using NiCuZn ferrite powder (Ni _0.1 Cu _0.3 Zn _0.6 OFe ₂ O ₃ ; specific surface area 10.25 m 2 / g).

Example 19

A NiCuZn ferrite paste was prepared in the same manner as in Example 13, using NiCuZn ferrite powder (Ni _0.4 Cu _0.3 Zn _0.3 OFe ₂ O ₃ ; specific surface area of 10.0 m 2 / g).

Experimental Example 3

The NiCuZn ferrite pastes prepared in Examples 14 to 19 were measured for viscosity in the same manner as in Experimental Example 1 and subjected to screen printing to measure printability, leveling degree, and precision of printed lines. Shown in

division Viscosity (mPa.s) SVI (m) result Screen (100s ^-1 ) Leveling (0.1s ^-1 ) Printability Leveling Line precision Example 14 20,510 2,469,000 120.4 (0.794) ◎ ○ ◎ Example 15 137,300 2,552,000 185.8 (0.760) ○ ○ ◎ Example 16 42,000 2,245,000 153.4 (0.788) ◎ ○ △ Example 17 24,610 2,841,000 215.4 (0.790) ◎ ◎ ◎ Example 18 34,660 2,952,000 185.2 (0.781) ◎ ○ ○ Example 19 17,000 1,424,000 283.8 (0.741) ◎ ○ ○ (Note) ◎: Very good ○: Good △: Normal ×: Bad

As shown in Table 4, in Examples 14 to 19, the paste was prepared by varying the chemical composition of the NiCuZn ferrite powder. As a result, line precision was obtained in the ferrite paste (Example 16) prepared with a Zn content of 0.75 molar ratio. Was moderate, but overall showed good printability, leveling and line precision.

As described above, the NiCuZn ferrite paste according to the present invention can not only manufacture smaller chips by precisely laminating the soft magnetic layer using the screen printing method, but also eliminate the need for purchasing an expensive punching machine and screening the main lamination process. It can be done by printing method, so it can save not only the initial investment but also the maintenance cost, and it is a hybrid chip component that combines multilayer chip inductor, transformer, or resistor or condenser. It is suitable for the formation of a magnetic layer during the production of high-volume, high-volume production with high yield and automation process, and excellent viscosity characteristics while maintaining high ferrite concentration during silk screen printing with excellent smoothness and dispersion stability. It can be seen that there is an effect that enables thin and precise printing.

Claims (7)

A NiCuZn ferrite paste, wherein the NiCuZn ferrite represented by the following formula (1) contains a polyvinyl butyral-vinyl alcohol-vinylacetate copolymer as a binder component. Formula 1 Ni _x Cu _y Zn _z OFe ₂ O ₃ In Formula 1, x is 0.1 to 0.55, y is 0.15 to 0.3, z is 0.3 to 0.75, and x + y + z = 1. The NiCuZn ferrite paste according to claim 1, wherein the polyvinyl butyral-vinyl alcohol-vinylacetate copolymer has a molecular weight distribution in the range of 5,000 to 120,000. The NiCuZn ferrite paste according to claim 1, wherein the polyvinyl butyral-vinyl alcohol-vinylacetate copolymer is contained in an amount of 3 to 6 parts by weight based on 100 parts by weight of the NiCuZn ferrite powder. The NiCuZn ferrite paste according to claim 1, wherein the NiCuZn ferrite paste contains a solvent in an amount of 25 to 35 parts by weight based on 100 parts by weight of the NiCuZn ferrite powder. The polyvinyl butyral-vinyl alcohol copolymer according to claim 2, wherein the polyvinyl butyral-vinyl alcohol-vinylacetate copolymer has a low molecular weight of 50,000 to 80,000, a medium molecular weight of 70,000 to 100,000, and a high molecular weight distribution of 90,000 to 120,000. NiCuZn ferrite paste, characterized in that it is a mixture of vinyl acetate copolymer. The method of claim 5, wherein the polyvinyl butyral-vinyl alcohol-vinylacetate copolymer is characterized in that each polyvinyl butyral-vinyl alcohol-vinylacetate copolymer is mixed in the range of 25 to 50% by weight. NiCuZn Ferrite Paste. The NiCuZn ferrite paste according to claim 1, wherein the NiCuZn ferrite paste has a screen viscose index (SVI) of 100 to 300 and a pseudo plastic index index m of 0.7 to 0.85.