High-density and high-strength LTCC (Low Temperature Co-Fired Ceramic) raw ceramic chip as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of low-temperature co-fired ceramics, and particularly relates to a high-density and high-strength LTCC (Low Temperature Co-fired Ceramic) raw ceramic chip as well as a preparation method and application thereof. The preparation method comprises the steps that stacking phase powder and filling phase powder in raw materials are fully mixed and then subjected to tape casting, the equivalent particle size ratio of the stacking phase powder to the filling phase powder is 1: (0.4-0.8), and the volume ratio of the stacking phase powder to the filling phase powder is 1: (0.15-0.45). The high-density and high-strength LTCC raw ceramic chip is used for preparing a low-temperature co-fired ceramic substrate. According to the technical scheme provided by the invention, the raw ceramic chip raw materials can be tightly arranged after being fully mixed through the inorganic powder with different particle sizes and matching the dosage ratio of the inorganic powder to the raw ceramic chip raw materials, and low porosity in the sintered substrate is realized on the basis of not changing the substrate raw material composition or crystal whiskers; and therefore, the bending strength is improved, and other properties are not influenced.

Description

Technical Field

[0001] The invention belongs to the technical field of low temperature co-fired ceramics, and in particular relates to a high-density and high-strength LTCC green ceramic sheet and a preparation method and application thereof. Background Art

[0002] Low Temperature Cofired Ceramic (LTCC) meets the development trend of modularization and integration of electronic components, and has been increasingly used in the field of semiconductor packaging in recent years. The trend of continuous miniaturization and high integration of packaging has put forward higher requirements on the bending strength of LTCC substrates. LTCC raw ceramic sheets are the most basic functional materials for LTCC substrates, and are usually prepared by casting after ball milling of glass powder, ceramic powder, binder, dispersant, plasticizer, solvent, etc. LTCC raw ceramic sheets are prepared into LTCC substrates through processes such as lamination, isostatic pressing, and sintering.

[0003] The existing LTCC substrate reinforcement methods mainly include: changing the composition of glass powder or ceramics to increase the Young's modulus of the material; introducing tree-like fibers / whiskers to increase the substrate strength by using the pull-out effect; increasing the material density and reducing the porosity. However, the first two methods will change the composition of the LTCC substrate, which will affect the dielectric constant and dielectric damage while improving the strength.

[0004] Chinese patent CN116217254A discloses a fiber-reinforced LTCC substrate. In order to avoid adverse effects of heterogeneous fillers on key properties of the substrate, glass fibers of the same nature as the LTCC substrate are selected as reinforcing fillers to improve the strength of the substrate. However, this solution may induce the disadvantage of inconsistent X / Y shrinkage rates during sintering.

[0005] Porosity is the main factor affecting substrate strength. When the porosity is similar, the crystalline content will affect the bending strength. However, there is currently little public information reporting on how to prepare high-density LTCC substrate materials in the LTCC system. Summary of the invention

[0006] The present invention provides a high-density and high-strength LTCC green ceramic sheet and a preparation method and application thereof, which are used to solve the problem that the improvement of the bending strength of the current LTCC substrate will lead to the deterioration of key performance.

[0007] In order to solve the above technical problems, the technical solution of the present invention is: the preparation method of the high-density and high-strength LTCC raw ceramic sheet comprises the following steps: fully mixing the stacking phase powder and the filling phase powder in the raw material and then performing tape casting, the equivalent particle size ratio of the stacking phase powder to the filling phase powder is 1:(0.4-0.8), and the volume ratio of the stacking phase powder to the filling phase powder is 1:(0.15-0.45).

[0008] Optionally, the equivalent particle size ratio of the stacking phase powder to the filling phase powder is 1:(0.5-0.6), and the volume ratio of the stacking phase powder to the filling phase powder is 1:(0.35-0.45).

[0009] Optionally, the particle size distribution span (Span value) (D90-D10) / D50 of the packing phase powder is below 0.7, and the particle size distribution span (D90-D10) / D50 of the filling phase powder is below 0.7.

[0010] Optionally, the bulk phase powder is selected from one or more of aluminum nitride, aluminum oxide, cordierite and mullite.

[0011] Optionally, the filling phase powder is microcrystalline glass powder.

[0012] Optionally, the filling phase powder includes one or more components selected from the group consisting of CaO (calcium oxide), SiO2 (silicon oxide), B2O3 (boron oxide), Al2O3 (aluminum oxide), Li2O (lithium oxide) and K2O (potassium oxide).

[0013] Optionally, in the filling phase powder, the sum of CaO, SiO2 and B2O3 is 80-100wt% calculated by weight.

[0014] Optionally, the stacking phase powder is spherical particles, and the filling phase powder is spherical or ellipsoidal particles.

[0015] Optionally, the equivalent particle size of the bulk phase powder is 2-7 μm, preferably 3-6 μm.

[0016] Optionally, the raw materials further include a binder, a plasticizer, a dispersant and a solvent, and the ratio of the total volume of the binder and the plasticizer to the total volume of the bulk phase powder is (0.45-0.75):1, preferably (0.5-0.6):1.

[0017] In raw porcelain, there will still be pores between the stacking phase and the filling phase. The purpose of this ratio is to fill these pores. If there is too much, it may overflow, which is not good for the sintering strength.

[0018] Optionally, the binder is selected from PVB (polyvinyl butyral), the plasticizer is selected from DBP (dibutyl phthalate), the dispersant is selected from castor oil, and the solvent is a mixture of xylene and ethanol.

[0019] Optionally, the stacking phase powder, filling phase powder, solvent and dispersant in the raw material are mixed and then ball-milled for the first time for 20-30 hours; then a binder and a plasticizer are added and ball-milled for the second time for 20-30 hours; finally, the slurry is tape-cast.

[0020] The present invention also provides a high-density and high-strength LTCC green ceramic sheet, which is prepared by using the above-mentioned method for preparing the high-density and high-strength LTCC green ceramic sheet.

[0021] The present invention also provides a low-temperature co-fired ceramic substrate, which is prepared by using the above-mentioned high-density and high-strength LTCC green ceramic sheets as raw materials through the processes of lamination, isostatic pressing, debinding and sintering.

[0022] Optionally, the debinding temperature is 400-500°C, and the sintering temperature is 800-900°C.

[0023] The technical solution provided by the present invention has the following advantages over the prior art: by using two inorganic powders with different particle sizes and matching the dosage ratio of the two, the raw materials of the raw ceramic sheets can be closely arranged after being fully mixed, and low porosity in the sintered substrate can be achieved without changing the composition of the substrate raw materials or whiskers, thereby achieving the effect of improving the bending strength while not affecting other properties. DETAILED DESCRIPTION

[0024] For ease of understanding, the high-density and high-strength LTCC green ceramic sheet and its preparation method and application are described below in conjunction with embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0025] Example 1

[0026] The raw material components and preparation method of the green porcelain sheet are as follows:

[0027] LTCC powder includes bulk phase powder and filler phase powder.

[0028] Bulk phase powder: mullite (purchased from DAIHAN REFRACTORIES MATERIAL, Seoul, Korea, sieved by ourselves), equivalent particle size 3.4 μm, span value 0.65.

[0029] Filling phase powder: microcrystalline glass powder (homemade, 27wt% CaO, 45wt% SiO2, 27wt% B2O3, 1mol% Li2O), equivalent particle size 2μm, Span value 0.63.

[0030] The volume ratio of microcrystalline glass powder to mullite is 0.41, and the particle size ratio is 0.59.

[0031] Binder: PVB, particle size <4μm; Plasticizer: DBP.

[0032] The volume ratio of the total volume of the binder and the plasticizer to the volume of the LTCC powder is 0.6.

[0033] Dispersant: castor oil, with a volume ratio of 0.30 to LTCC powder.

[0034] Solvent: xylene-ethanol mixed solution, with a volume ratio of 1:1 to LTCC powder.

[0035] After the LTCC powder, solvent and dispersant are ball-milled for 24 hours, a binder and a plasticizer are added and ball-milled for a second time for 24 hours. The slurry is tape-casted to obtain the high-density and high-strength LTCC green ceramic sheet.

[0036] The high-density and high-strength LTCC green ceramic sheets prepared above are then laminated, isostatically pressed, debonded and sintered to obtain an LTCC substrate.

[0037] The debinding temperature is 500 degrees Celsius and the sintering temperature is 850 degrees Celsius.

[0038] Example 2

[0039] The raw material components and preparation method of the green porcelain sheet are as follows:

[0040] LTCC powder includes bulk phase powder and filling phase powder.

[0041] Bulk phase powder: alumina (Japan Light Metal, SA43A, self-screening), equivalent particle size 3.2 μm, Span value 0.55.

[0042] Filling phase powder: microcrystalline glass powder (self-made, 18wt% CaO, 50wt% SiO2, 12wt% Al2O3, 15wt% B2O3, 5wt% K2O), equivalent particle size 1.8μm, Span value 0.67.

[0043] The volume ratio of microcrystalline glass powder to alumina is 0.45, and the particle size ratio is 0.56.

[0044] Binder: PVB, particle size <4μm; Plasticizer: DBP.

[0045] The volume ratio of the total volume of the binder and plasticizer to the volume of the LTCC powder is 0.56.

[0046] Dispersant: castor oil, with a volume ratio of 0.30 to LTCC powder.

[0047] Solvent: xylene-ethanol mixed solution, with a volume ratio of 1:1 to LTCC powder.

[0048] After the LTCC powder, solvent and dispersant are ball-milled for 24 hours, a binder and a plasticizer are added and ball-milled for a second time for 24 hours. The slurry is tape-casted to obtain the high-density and high-strength LTCC green ceramic sheet.

[0049] The high-density and high-strength LTCC green ceramic sheets prepared above are then laminated, isostatically pressed, debonded and sintered to obtain a LTCC substrate.

[0050] The debinding temperature is 500℃ and the sintering temperature is 875℃.

[0051] Comparative Example 1

[0052] The difference from Example 1 is that the particle size of the mullite is 1.9 μm, that is, the particle size ratio of the filling phase powder to the packing phase powder is approximately 1:1.

[0053] Comparative Example 2

[0054] The difference from Example 1 is that the Span value of the particle size distribution of mullite is 2.2.

[0055] Comparative Example 3

[0056] The difference from Example 1 is that the Span value of the particle size distribution of the microcrystalline glass powder is 2.8.

[0057] Comparative Example 4

[0058] The difference from Example 1 is that the volume ratio of microcrystalline glass powder to mullite is 0.23.

[0059] Comparative Example 5

[0060] The difference from Example 1 is that the mullite is an ellipsoidal particle, and the SEM measurement result shows that the ratio of the major diameter to the minor diameter is about 1.5.

[0061] Comparative Example 6

[0062] The difference from Example 2 is that the packing phase is alumina (Japan Light Metal, SA41A, particle size 1.2 μm), that is, the particle size ratio of the filling phase powder to the packing phase powder is 0.38.

[0063] Performance Experiment

[0064] 1. Substrate density: The substrate density is measured using the Archimedean drainage method.

[0065] 2. Bending strength: Measure the bending strength of the substrate in accordance with GB / T 6569-2006.

[0066] 3. Equivalent particle size: Use a laser particle size analyzer to measure the equivalent particle size of the particles.

[0067] 4. Particle size distribution: Calculate the particle size distribution span (Span value) through the particle size distribution data of the laser particle size analyzer

[0068] That is (D90-D10) / D50.

[0069] 5. The dielectric constant and dielectric loss are tested in accordance with GB / T 5594.4-2015 standard.

[0070] The LTCC substrates prepared in Examples 1 and 2 and Comparative Examples 1-5 were subjected to the above performance tests, and the experimental data are shown in Table 1.

[0071] Table 1

[0072] Substrate density g / cm3 Bending strength MPa Dielectric constant 1MHz Dielectric loss 1MHz Example 1 2.89 150 4.8 0.016 Example 2 3.1 226 6.5 0.003 Comparative Example 1 2.65 103 4.0 0.025 Comparative Example 2 2.71 123 4.6 0.019 Comparative Example 3 2.72 130 4.7 0.019 Comparative Example 4 2.58 53 3.2 0.223 Comparative Example 5 2.80 136 4.1 0.018 Comparative Example 6 2.66 119 4.5 0.020

[0073] Summary: By comparing Example 1 with Comparative Examples 1-5, it can be found that the particle size ratio of filling phase powder to packing phase powder, the particle size distribution and shape of filling phase / packing phase powder, and the volume ratio of filling phase powder to packing phase powder will affect the basic density, flexural strength, dielectric constant and dielectric loss, among which the volume ratio of filling phase powder to packing phase powder has the greatest influence. Through Example 2 and Comparative Example 6, it can be found that changes in the particle size ratio of filling phase powder to packing phase powder will also seriously affect various performance parameters.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high-density and high-strength LTCC green ceramic sheet, characterized in that: The method comprises the following steps: fully mixing the stacking phase powder and the filling phase powder in the raw material and then tape casting, wherein the equivalent particle size ratio of the stacking phase powder to the filling phase powder is 1:(0.4-0.8), and the volume ratio of the stacking phase powder to the filling phase powder is 1:(0.15-0.45).

2. The method for preparing the high-density and high-strength LTCC green ceramic sheet according to claim 1, characterized in that: The equivalent particle size ratio of the stacking phase powder to the filling phase powder is 1:(0.5-0.6), and the volume ratio of the stacking phase powder to the filling phase powder is 1:(0.35-0.45).

3. According to claim 1, the particle size distribution span (D90-D10) / D50 of the stacking phase powder is less than 0.7, and the particle size distribution span (D90-D10) / D50 of the filling phase powder is less than 0.

7.

4. The method for preparing the high-density and high-strength LTCC green ceramic sheet according to claim 1, characterized in that: The stacking phase powder is selected from one or more of aluminum nitride, aluminum oxide, cordierite and mullite.

5. The method for preparing the high-density and high-strength LTCC green ceramic sheet according to claim 1, characterized in that: The filling phase powder is microcrystalline glass powder.

6. The method for preparing the high-density and high-strength LTCC green ceramic sheet according to claim 1, characterized in that: The stacking phase powder is spherical particles, and the filling phase powder is spherical or ellipsoidal particles.

7. The method for preparing the high-density and high-strength LTCC green ceramic sheet according to claim 1, characterized in that: The equivalent particle size of the bulk phase powder is 2-7 μm, preferably 3-6 μm.

8. The method for preparing the high-density and high-strength LTCC green ceramic sheet according to claim 1, characterized in that: The raw materials also include a binder, a plasticizer, a dispersant and a solvent, and the total volume ratio of the binder and the plasticizer to the total volume ratio of the bulk phase powder is (0.45-0.75):1, preferably (0.5-0.6):1。 9. The method for preparing high-density and high-strength LTCC green ceramic sheets according to claim 1, characterized in that: The binder is selected from PVB (polyvinyl butyral), the plasticizer is selected from DBP (dibutyl phthalate), the dispersant is selected from castor oil, and the solvent is a mixture of xylene and ethanol.

10. A high-density and high-strength LTCC green ceramic sheet, characterized in that: The high-density and high-strength LTCC green ceramic sheet is prepared by the preparation method of any one of claims 1-8.

11. A low temperature co-fired ceramic substrate, characterized in that: The high-density and high-strength LTCC green ceramic sheet as claimed in claim 9 is used as a raw material and is prepared through lamination, isostatic pressing, binder removal and sintering processes.