KR100674860B1 - Glass frit for low temperature sintering - Google Patents

Abstract

A glass frit with constant composition of aSiO2-bB2O3-cAl2O3-dLi2O-eMnO2 for low temperature sintering is provided to prevent gelation and to improve acid resistance, moisture resistance and electric properties of sintered bodies after calcination by comprising SiO2, B2O3, Al2O3, Li2O and MnO2 with specific relative compositions thereof. The glass frit comprises constitutional compounds satisfying an equation of: aSiO2-bB2O3-cAl2O3-dLi2O-eMnO2 wherein a+b+c+d+e=100 and a ranges from 44 to 57mol%, b ranges from 10 to 19mol%, c ranges from 0.5 to 2.0mol%, d ranges from 30 to 37mol%, e ranges from 0 to 1.0mol%. Ratio of SiO2 to B2O3 satisfies that a/b ranges from 2.3 to 5.7. LTCC(low temperature co-fired ceramic) comprises 70 to 90wt.% of ceramic powder and 10 to 30wt.% of the glass frit. The ceramic powder is selected from MgTiO3, SrTiO3, CaTiO3, MgSiO4, BaTi4O9, Al2O3, TiO2, SiO2, (Mg,Ti)2(BO4)O, ZrO2 and combination thereof.

Description

Glass frit for low temperature sintering

1 is a scanning electron micrograph of the fracture surface of the sintered specimen.

2 is a microstructure photograph of an electrode portion and a body portion of a chip.

3 is a graph of electrical properties and physical properties according to sintering temperature.

4 is a graph showing the results of thermal analysis of glass.

Figure 5 is a photograph of the F / B test results for the glass.

The present invention relates to a glass frit for low temperature sintering. More specifically, the glass frit and the low-temperature fired magnetic composition and chip parts using the same, which can prevent the gelation due to the glass frit and improve the acid resistance, moisture resistance and electrical properties of the sintered body after firing in the slurry manufacturing process before firing. It is about.

Low temperature co-fired ceramics (hereinafter simply referred to as LTCC) are used for LC filters. LTCC is composed of glass frit and ceramic powder. This glass frit has a low softening temperature (L. Ts) and is required to allow the ceramic powder to be sintered at a low temperature of less than 1000 DEG C with a low softening temperature. For this purpose, a high content of alkali metal and B ₂ O ₃ is advantageous.

The glass frit developed in this respect is composed of SiO ₂ : 16.78 mol%, B ₂ O ₃ : 46.83 mol%, Li ₂ O: 31.75 mol%, BaO: 4.64 mol% (hereinafter referred to as conventional glass frit) ). A typical example of LTCC to which this glass frit is applied is CMT ceramic powder composed of MgTiO ₃ -CaTiO ₃ system. Conventional glass frit significantly improves the sinterability of CMT dielectrics.

However, the conventional glass frit is poor in moisture resistance and causes the electrical characteristics of the product to deteriorate over time in the reliability test under the high temperature and high humidity conditions of the LC-filter product. When the CMT powder and the conventional glass frit are added to the solvent solution to prepare a slurry, the glass frit constituents elute into the solvent solution. As a result, when a binder (polymer PVB: Poly Vinyl Butylal) is added, a B-OH bond is generated by a coupling reaction between the OH group of the binder and boron (B ₂ O ₃ ) of the glass frit. This leads to gelation of the slurry (dough due to the increase in viscosity). This gelation reaction causes a time-dependent change in which the green sheet produced in the thin film form during the molding process of the slurry (processing the slurry into a film having a thickness of several tens of microns) gradually cures over time (within 7 days). . As a result, the green sheet is cut to the same size, laminated in multiple layers, and the adhesiveness of the green sheet required in the process of pressing at high pressure is lost. This causes unbonded parts between the green sheets in the lamination process after compression, which causes defects in the electrical properties inspection after firing. The weakness of acid and moisture resistance is involved in the elution of the glass frit, affecting the long-term reliability of the LC filter. This causes OH to adhere to the glass frit in the LC-filter body due to moisture in the air. The adhesion of OH decreases the dielectric constant, which may lead to a decrease in long-term reliability. In addition, in the case of severe change over time, the disposal of the entire molding lot occurs to the extent that the handling of the green sheet is impossible, which greatly reduces the process yield.

As such, in order to improve the yield of LC-filter and improve the long-term reliability, improvement of glass frit is required. That is, the development of a new glass frit having improved acid resistance and moisture resistance, no slurry gelation occurs, and at the same time low temperature sinterability and electrical properties are required.

According to the present invention, the glass frit can satisfy both low-temperature sintering and acid resistance moisture resistance of glass frit, prevent gelation during slurry production, and secure dielectric constant and quality factor of the sintered body and magnetic using the same. The purpose is to provide a composition.

    Glass frit of the present invention for achieving the above object,

It is composed of aSiO ₂ -bB ₂ O ₃ -cAl ₂ O ₃ -dLi ₂ O-eMnO ₂ , satisfies a + b + c + d + e = 100, and in mol%, 44 ≦ a ≦ 57, 10 ≦ b≤19, 0.5≤c≤2.0, 30≤d≤37, and 0≤e≤1.0. In the present invention, the a, b, c, d, e is mol% 48≤a≤52, 12≤b≤16, 1.3≤c≤1.7, 32≤d≤36, 0.3≤e≤0.7 More preferred.

Hereinafter, the present invention will be described.

The present invention is to develop a glass frit composed of aSiO ₂ -bB ₂ O ₃ -cAl ₂ O ₃ -dLi ₂ O-eMnO ₂ through the following insights.

1) Even if a large amount of Li ₂ O is contained by increasing SiO ₂ , the glass network is stable to ensure improved acid and moisture resistance.

2) As the frequency increases, resonance occurs due to the natural vibration of the ions, and resonance loss occurs. Light ions such as B ₂ O ₃ and Li ₂ O can vibrate rapidly, causing resonance loss at high frequencies. Therefore, by reducing the content of B ₂ O _{3 It} is possible to improve the quality factor (Quality factor) that is an electrical characteristic value after firing of the dielectric.

3) If SiO ₂ is increased and B ₂ O ₃ is properly mixed with other components, a fine microstructure can be obtained and the quality factor can be increased.

4) The use of stable SiO ₂ as the main network structure element, and the addition of MnO ₂ with good diffusivity, can maintain the low temperature meltability and increase the stability under acid and moisture resistance of the glass frit.

The composition range of the glass frit of the present invention will be described.

The content of silicon oxide (SiO ₂ ) is preferably 44 to 57 mol%.

Silicon oxide is a glass network-former and has a structure in which Si atoms are bonded to four adjacent Si atoms with four oxygen atoms surrounding them. In the present invention, silicon oxide acts as the biggest factor in determining the softening temperature and acid resistance of the glass. For this purpose, the content of silicon oxide is preferably 44 mol% or more, and in the case of more than 57 mol%, the electrical properties after sintering may decrease due to the softening point of the glass frit.

The content of boron oxide (B ₂ O ₃ ) is preferably 10 to 19 mol%.

   Boron oxide is substituted with silicon oxide to reduce the temperature characteristics such as glass transition temperature, softening temperature. When the content of boron oxide is 10 mol% or more, it plays a role of lowering the softening temperature without significantly affecting chemical durability and mechanical strength. However, when the content of boron oxide is more than 19 mol%, it may weaken the structure of the glass and lead to a sharp decrease in chemical durability and mechanical strength.

The content of aluminum oxide (Al ₂ O ₃ ) is preferably 0.5 to 2.0 mol%.

Aluminum oxide acts as intersticial oxides in the glass structure, lengthening the glass, ie widening the working temperature range, increasing chemical durability and preventing crystallization. The amount of aluminum oxide is preferably 0.5 mol% or more, and in the case of more than 2.0 mol%, chemical durability may be improved, but the role of low temperature sintering aid may be lowered by causing an increase in softening temperature. Longening the glass means that the time period that varies from the time when the glass becomes soft until the flow viscosity of the glass becomes about 10 ² to 10 ⁵ is long.

The content of lithium oxide (Li ₂ O) is preferably 30 to 37 mol%.

Lithium oxide is preferably contained 30 mol% or more by lowering the softening temperature of the glass. When the content of lithium oxide is more than 37 mol%, the structure of the glass is weakened and the chemical durability and mechanical strength are drastically reduced.

The content of manganese dioxide (MnO 2) is preferably 0 to 1.0 mol% or less.

More preferably, the glass frit contains manganese dioxide in an amount of 1.0 mol% or less in order to increase the diffusibility of the glass and to improve the sintering property. In the case of more than 1.0 mol% of manganese dioxide, aggregation of the glass in the sintered body may be caused.

In the glass frit of the present invention the SiO ₂ and Of B ₂ O ₃ Rain under the following conditions It is preferable to satisfy a / b = 2.3-5.7. To increase SiO ₂ , In the component ratio relationship that lowers B ₂ O ₃ , the dielectric constant and quality factor, which are electrical properties after firing, can be reduced while stabilizing the network structure of the glass.

In the aSiO ₂ -bB ₂ O ₃ -cAl ₂ O ₃ -dLi ₂ O-eMnO ₂ component system of the present invention, a, b, c, d, and e are mol% of 48 ≦ a ≦ 52, 12 ≦ b ≦ 16, Most preferably, 1.3 ≦ c ≦ 1.7, 32 ≦ d ≦ 36, and 0.3 ≦ e ≦ 0.7. Under these conditions, a homogeneous crystalline is produced, resulting in the best electrical properties. In this case the SiO ₂ and Of B ₂ O ₃ Rain under the following conditions It is most preferable to satisfy a / b = 3-4.

The glass frit obtained according to the present invention can be applied to LTCC at low softening temperature.

Next, the manufacturing method of the glass frit of this invention is demonstrated. Here, the present invention will be described with reference to specific examples, but the present invention is not limited thereto.

First, each component is weighed so as to satisfy the composition of the glass frit, sufficiently mixed, and then melted at 1250 to 1400 ° C. After quenching through a twin roller (twin roller) to obtain a glass flake and dry it and wet it to prepare a glass frit having an appropriate particle size. This glass frit can be used as glass of LTCC. A representative example is CMT ceramics.

Next, the LTCC to which the glass frit of this invention is applied is demonstrated.

LTCC is composed of ceramic powder and glass frit. To the ceramic powder as _{MgTiO 3, SrTiO 3, CaTiO 3} , Mg 2 SiO 4, BaTi 4 O 9, Al 2 O 3, TiO 2, SiO 2, (Mg, Ti) 2 (BO 4) O, ZrO 2 The component system to combine these is known. In addition, CMT ceramic powder is known, and the powder is composed of MgTiO ₃ -CaTiO ₃ system.

The glass frit of the present invention is applied to LTCC, the content of which is 70 to 90% by weight of the ceramic powder and 10 to 30% by weight of the glass frit of the present invention. The same applies to CMT.

When the glass frit of the present invention is applied to CMT, it can satisfy both low temperature sintering and acid resistance resistance of glass frit, prevent gelation during slurry production, and secure the dielectric constant and quality factor of the sintered body. have.

According to the present invention, the LTCC composed of the glass frit and CMT of the present invention is used as a chip component. Chip components include LC filter, LC array, and EMI filter. Representatively, the chip component of the present invention will be described using an LC filter as an example. The description herein is for better understanding, and the present invention is not limited thereto.

The LC filter is a laminate in which a dielectric layer and an internal circuit electrode layer are alternately stacked, and an external electrode is formed on the laminate. The inner and outer electrodes are made of Ag. The dielectric layer is comprised of the composition which mix | blended CMT powder and glass frit. The plating layer can be formed on the sintered layer. The plating layer is formed of a plating layer made of Ni and Sn.

The LC filter prepares the CMT powder raw material, which is a high dielectric material produced by high temperature calcination, as the starting material of the dielectric and the glass frit of the present invention. The prepared raw materials are mixed at a predetermined composition ratio, and then, an organic binder is added to the mixed powder to slurry. This slurry is shape | molded in a sheet form. Via holes are formed in the sheet by punching operations. Internal and external electrodes are formed on the sheet. A sheet having internal and external electrodes is laminated and crimped as necessary, and then a laminate is formed. The laminate is low temperature sintered at a temperature of less than 1000 ° C. In addition, a plating layer is formed on the electrode formed outside the laminate to complete the LC filter.

Hereinafter, the present invention will be described in more detail with reference to Examples.

 EXAMPLE

After weighing each element of the SiO ₂ -B ₂ O ₃ -Al ₂ O ₃ -Li ₂ O-MnO ₂ system so as to have a composition as shown in Table 1 below, and melted at 1400 ℃ at a temperature rising rate of 10K / min It was quenched through a twin roller and made into glass flakes.

The glass frit was manufactured so that the glass average particle size might be 1.0 micrometer or less using dry grinding and wet grinding using alcohol.

division Composition (mol%) SiO ₂ B ₂ O ₃ Al ₂ O ₃ Li ₂ O MnO ₂ BaO Inventive Example 1 50 14 1.5 34 0.5 - Inventive Example 2 57 10 2.0 30 1.0 - Inventive Example 3 44 18.9 0.5 36.5 0.1 - Inventive Example 4 50 14 2.0 34 - - Conventional example 17 46.84 - 31.75 - 4.64

Evaluation of the physical properties of the glass was as follows.

(1) softening temperature

Softening temperature was measured at a temperature rising rate of 10 K / min using TG / DTA and high temperature microscope.

(2) acid and moisture resistance

Acid resistance was measured by weight loss due to glass elution in Ni-plating solution for more than 8 hours, and moisture resistance was measured by dipping in distilled water for more than 24 hours.

(3) gelation state

A slurry was prepared with the CMT powder to visually confirm the gelled state. As the CMT powder, a mixture of MgTiO ₃ : CaTiO ₃ = 10: 1 was used.

(4) Electrical characteristics and low temperature sintering

K2 specimens were prepared and measured. The sinterability with the dielectric was observed in the microstructure of the fired K2 specimen using a scanning electron microscope (SEM) and the results are shown in FIG.

division Softening temperature Acid resistance Moisture resistance Inventive Example 1 574 ℃ 1.16% 0.41% Inventive Example 2 592 ℃ 0% 0% Inventive Example 3 567 ℃ 2.43% 7.12% Inventive Example 4 572 ℃ 1.59% 1.47% Conventional example 540 ℃ 38% 17.7%

division Shrinkage Sintered Density Q permittivity Gelation Inventive Example 1 20.21% 3.48 1790 16.92 × Inventive Example 2 20.11% 3.44 1183 16.24 × Inventive Example 3 20.39% 3.42 1998 17.59 × Inventive Example 4 20.11% 3.44 1697 17.12 × Conventional example 17.82% 3.3 1594 17.03 ○ ×: gelation does not occur, ○: gelation occurs

As shown in Tables 1 to 3, it is understood that Inventive Examples 1 to 4 had a high sintered density and a high Q value without the occurrence of gelation.

On the other hand, Figure 1 is a microstructure photograph of the specimen (sintered for 40 minutes at 925 ℃) composed of 85% CMT and 15% glass frit. Inventive Examples 1 (FIGS. 1A) to 4 (FIG. 1D) all have a dense microstructure.

2 shows the microstructure of Inventive Example 1 and the prior art example. This specimen is also composed of 85% CMT and 15% glass frit. Referring to Figure 2, while the pores are seen in the conventional specimen, Example 1 has a dense structure.

Figure 3 shows the electrical and physical properties according to the sintering temperature for the glass frit of Example 1 and the prior art. Considering both electrical and physical properties, it can be seen that the sintering temperature around 925 ° C is the best.

Figure 4 shows the thermal analysis results for the glass of Inventive Examples 1-4.

In the case of Inventive Example 1, it can be seen that the remelting degree of the crystalline previously produced was about the highest at about 925 ° C. This means that the CMT and the glass increase the wetting at the sintering temperature, and it is assumed that it means the promotion of the sintering.

5 shows a result of performing a flow button test by molding a disk with the glass frit powder of Inventive Examples 1 to 4. FIG. The flow button test is an experiment to examine how glass frit behaves during the firing temperature increase while forming the glass frit disk and raising the temperature to the firing temperature.

In the case of FIG. 5A (Inventive Example 1), uniform crystalline is produced.

FIG. 5B (Invention Example 2) is divided into a central glass part and an edge crystallization part. Formation of glass quality causes a decrease in electrical characteristics.

5c (invention example 3) shows the separation of the crystalline phase and the liquid phase. The content of alkali is the highest, which leads to excellent mobility, but a slight decrease in sintering density.

FIG. 5D (Inventive Example 4) is a MnO ₂ free composition, which has a difference in mobility of glass compared to Inventive Example 1. FIG. This increases the diffusibility of the glass by MnO ₂ content.

       As described above, according to the present invention, it is possible to prevent the separation phenomenon of the laminated and compressed green sheet due to the change of the green sheet over time while ensuring low temperature sintering resistance and excellent acid and moisture resistance. In addition, the dielectric constant and quality factor values of the sintered body can be secured, thereby improving the frequency loss characteristics of the chip parts to increase reliability.

Claims (4)

It is composed of aSiO ₂ -bB ₂ O ₃ -cAl ₂ O ₃ -dLi ₂ O-eMnO ₂ , satisfies a + b + c + d + e = 100, and in mol%, 44 ≦ a ≦ 57, 10 ≦ Low temperature sintered glass frit that satisfies b ≦ 19, 0.5 ≦ c ≦ 2.0, 30 ≦ d ≦ 37, and 0 ≦ e ≦ 1.0. The method of claim 1, wherein the SiO ₂ and Of B ₂ O ₃ Rain under the following conditions Low temperature sintered glass frit characterized by satisfying a / b = 2.3 to 5.7. The method of claim 1, wherein a, b, c, d, and e are mol% of 48 ≦ a ≦ 52, 12 ≦ b ≦ 16, 1.3 ≦ c ≦ 1.7, 32 ≦ d ≦ 36, and 0.3 ≦ e ≦ 0.7. The low temperature sintering glass frit. The method of claim 3, wherein the SiO ₂ and B ₂ O ₃ ratio of the glass for a low temperature co-fired to satisfy the following conditions: a / b = 3 ~ 4 frit.

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