A printing high-temperature conductor paste for an HTCC ceramic substrate and a preparation method thereof

Abstract

This invention discloses a high-temperature conductor printing paste for HTCC ceramic substrates and its preparation method, belonging to the field of electronic paste technology. The paste comprises the following raw materials by weight percentage: 65%–75% tungsten powder, 15%–25% organic carrier, 2%–6% Al₂O₃ powder, 2%–5% Y₂O₃ powder, and 1%–4% vermiculite powder. By adding vermiculite powder to the tungsten paste formulation, the flake-like vermiculite powder, with its large specific surface area and aspect ratio, forms a continuous, loose, yet stable three-dimensional network structure within the paste. The denser tungsten powder particles are encapsulated and confined within the voids of this three-dimensional network structure, making it difficult for them to settle freely and thus inhibiting the sedimentation of the tungsten paste. This invention significantly improves the problem of sedimentation and precipitation in printed tungsten paste, which affects its usability. Furthermore, the addition of vermiculite powder has no negative impact on the printability and sintering properties of the paste, and the warpage of the paste co-fired with the substrate is slightly reduced.

Description

Technical Field

[0001] This invention belongs to the field of electronic paste technology, specifically relating to a printing high-temperature conductor paste for HTCC ceramic substrates and its preparation method. Background Technology

[0002] High-temperature co-fired ceramics (HTCC) technology is an important multilayer ceramic manufacturing process widely used in aerospace, military electronics, high-power LEDs, and automotive electronics to produce high-reliability, high-temperature-resistant, and harsh-environment-resistant multilayer ceramic substrates, packaging shells, and circuit components. In this field, tungsten paste, as a key metallization material, directly determines the performance and yield of multilayer ceramic components due to its stability. However, during storage and use, tungsten paste exhibits significant challenges due to the extremely high density of tungsten powder (approximately 19.3 g / cm³). 3 When left to stand, tungsten powder particles undergo gravitational sedimentation in the slurry system, leading to solid-liquid separation. A hard precipitate forms at the bottom, while a clear organic phase precipitates on top. This not only affects the printing performance of the slurry but also causes a series of quality problems, such as uneven film formation after sintering, sheet resistance fluctuations, and decreased metallization bonding strength. Therefore, in-depth analysis of its sedimentation mechanism and exploration of effective suppression methods have become crucial technical challenges in the development of HTCC tungsten slurries. Summary of the Invention

[0003] The purpose of this invention is to improve the problem of solid-liquid separation caused by gravity sedimentation of tungsten powder particles during the storage and use of HTCC printing tungsten paste, and to provide a high-temperature conductor printing paste for HTCC ceramic substrates with significantly improved sedimentation and precipitation problems, as well as its preparation method.

[0004] The high-temperature conductor printing paste for HTCC ceramic substrates provided by this invention comprises the following raw materials by weight percentage: 65%–75% tungsten powder, 15%–25% organic carrier, 2%–6% Al2O3 powder, 2%–5% Y2O3 powder, and 1%–4% vermiculite powder.

[0005] Furthermore, the tungsten powder comprises two types: coarse powder and fine powder, both of which conform to a normal distribution in particle size. The average particle size of the coarse powder is 5–7 μm, and the average particle size of the fine powder is 1.5–2 μm. The weight ratio of coarse powder to fine powder is 1:1 to 2:1.

[0006] Furthermore, the organic carrier comprises the following raw materials in weight percentages: 12%–18% ethyl cellulose, 1%–3% polyamide wax powder, 0.5%–1% soybean lecithin, 45%–65% terpineol, and 20%–35% dodecyl alcohol.

[0007] Furthermore, the vermiculite powder is in flake form, and its particle size conforms to a normal distribution with an average particle size of 2–5 μm.

[0008] Furthermore, the particle size of the Al2O3 powder and Y2O3 powder is 0.5–2 μm.

[0009] The preparation method of the above-mentioned high-temperature conductor paste for printing on HTCC ceramic substrates is as follows: according to the weight percentage of the above paste, Al2O3 powder and Y2O3 powder are mixed with 1 / 5 to 1 / 4 organic carrier, and then rolled evenly with a three-roll mill to obtain a paste intermediate; the paste intermediate, vermiculite powder, remaining organic carrier, and tungsten powder are mixed and rolled with a three-roll mill to a fineness of less than 10μm.

[0010] Furthermore, the preparation method of the organic carrier is as follows: according to the weight percentage of the organic carrier, terpineol and dodecyl alcohol are mixed, ethyl cellulose is added during heating and stirring, and after stirring evenly, polyamide wax powder and soybean lecithin are added. The mixture is stirred until the solution is homogeneous and stable, and then cooled to obtain the organic carrier.

[0011] Furthermore, the heating and stirring temperature is set to 65–85°C, and the stirring speed is 600–1000 r / min.

[0012] The beneficial effects of this invention are as follows:

[0013] This invention introduces vermiculite powder into the tungsten paste formulation. The vermiculite powder, in the form of thin flakes, possesses a large specific surface area and high aspect ratio, allowing for uniform dispersion within the paste. These flake-like particles interlock and overlap, forming a continuous, loose, and stable three-dimensional network structure through physical interactions such as van der Waals forces. Tungsten particles (heavy particles with a density much greater than the solvent) are encapsulated and confined within the voids of this network structure. For sedimentation to occur, the tungsten particles must overcome the mechanical resistance of the network, displacing or breaking the surrounding vermiculite flakes. This three-dimensional network structure provides sufficient yield stress to effectively support the tungsten particles, preventing them from freely settling and thus significantly suppressing sedimentation and precipitation in the tungsten paste. Furthermore, the addition of vermiculite powder has no negative impact on the printability and sintering properties of the tungsten paste, and the warpage of the tungsten paste co-fired with the substrate is slightly reduced. Attached Figure Description

[0014] Figure 1 The sedimentation of the printed conductor paste in Examples 1-4 and the control example after 30 days of storage is shown. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0016] Example 1

[0017] The weight percentage composition of the printed conductor paste in this embodiment is as follows: 40% coarse tungsten powder, 30% fine tungsten powder, 25% organic carrier, 2% Al2O3 powder, 2% Y2O3 powder, and 1% vermiculite powder. The coarse powder has a particle size D50 of 5.8 μm, the fine powder has a particle size D50 of 1.5 μm, the Al2O3 powder has a particle size D50 of 1 μm, the Y2O3 powder has a particle size D50 of 1.5 μm, and the vermiculite powder has a particle size D50 of 2.8 μm. The organic carrier has the following weight percentage composition: 15% ethyl cellulose, 2% polyamide wax micron powder, 0.5% soybean lecithin, 60% terpineol, and 22.5% dodecyl alcohol ester.

[0018] The method for preparing the printed conductor paste in this embodiment includes the following steps:

[0019] Step 1: Mix 6g terpineol and 2.25g terpineol, and slowly add 1.5g ethyl cellulose while heating and stirring. After stirring evenly, add 0.2g polyamide wax powder and 0.05g soybean lecithin. Stir at 75℃ and 800r / min for 1 hour to make the solution homogeneous and stable. After cooling, the organic carrier is obtained.

[0020] Step 2: Mix 4g of Al2O3 powder, 4g of Y2O3 powder, and 10g of organic carrier, and roll them evenly with a three-roll mill to obtain a paste-like intermediate.

[0021] Step 3: Mix the paste intermediate obtained in Step 2 with 2g vermiculite powder, 40g organic carrier, 80g coarse tungsten powder and 60g fine tungsten powder, and roll it with a three-roll mill to a fineness of less than 10μm to obtain the printing conductor paste.

[0022] Example 2

[0023] The weight percentage composition of the printed conductor paste in this embodiment is as follows: 40% coarse tungsten powder, 30% fine tungsten powder, 24% organic carrier, 2% Al2O3 powder, 2% Y2O3 powder, and 2% vermiculite powder. Other raw material indicators and preparation methods are the same as in Example 1.

[0024] Example 3

[0025] The weight percentage composition of the printed conductor paste in this embodiment is as follows: 40% coarse tungsten powder, 30% fine tungsten powder, 23% organic carrier, 2% Al2O3 powder, 2% Y2O3 powder, and 3% vermiculite powder. Other raw material indicators and preparation methods are the same as in Example 1.

[0026] Example 4

[0027] The weight percentage composition of the printed conductor paste in this embodiment is as follows: 40% coarse tungsten powder, 30% fine tungsten powder, 22% organic carrier, 2% Al2O3 powder, 2% Y2O3 powder, and 4% vermiculite powder. Other raw material indicators and preparation methods are the same as in Example 1.

[0028] Compare with Example 1

[0029] The weight percentage composition of the printed conductor paste in this comparative example is: 40% coarse tungsten powder, 30% fine tungsten powder, 26% organic carrier, 2% Al2O3 powder, and 2% Y2O3 powder. Other raw material parameters and preparation methods are the same as in Example 1.

[0030] A portion of the printed conductor paste prepared in Examples 1-4 and Comparative Example 1 was placed in a transparent glass bottle and left for 30 days. The sedimentation of the paste was compared, and the results were as follows: Figure 1 As shown in Table 1. Meanwhile, after testing the viscosity of the remaining printed conductor paste after it was removed from the printing press, it was placed in a container for 30 days, and the viscosity change was compared.

[0031] Table 1. Viscosity test data of different printed conductor pastes

[0032]

[0033] Figure 1 The test results in Table 1 show that the present invention significantly improves the sedimentation and precipitation problem that easily occurs in the printing conductor paste for HTCC during the placement process by adding vermiculite powder to the tungsten paste.

[0034] After the sedimentation and precipitation problem was improved, the printed conductor pastes of the examples and control examples were further tested for printing and sintering. The test results are shown in Table 2.

[0035] Table 2. Printing and Sintering Test Data of Printed Conductor Paste

[0036]

[0037] The test data in Table 2 show that adding vermiculite powder to tungsten paste has no negative impact on the printability and sintering of the paste, and the warpage of the paste and substrate is slightly reduced after adding vermiculite powder.

Claims

1. A printing high-temperature conductor paste for HTCC ceramic substrates, characterized in that, The slurry comprises the following raw materials by weight percentage: 65%–75% tungsten powder, 15%–25% organic carrier, 2%–6% Al2O3 powder, 2%–5% Y2O3 powder, and 1%–4% vermiculite powder.

2. The high-temperature conductor printing paste for HTCC ceramic substrates according to claim 1, characterized in that, The tungsten powder includes two types: coarse powder and fine powder. The particle size of both conforms to a normal distribution. The average particle size of the coarse powder is 5-7 μm, and the average particle size of the fine powder is 1.5-2 μm. The weight ratio of coarse powder to fine powder is 1:1 to 2:

1.

3. The high-temperature conductor printing paste for HTCC ceramic substrates according to claim 1, characterized in that, The organic carrier comprises the following raw materials in weight percentage: 12%–18% ethyl cellulose, 1%–3% polyamide wax powder, 0.5%–1% soybean lecithin, 45%–65% terpineol, and 20%–35% dodecyl alcohol.

4. The high-temperature conductor printing paste for HTCC ceramic substrates according to claim 1, characterized in that, The vermiculite powder is in flake form, and its particle size conforms to a normal distribution with an average particle size of 2–5 μm.

5. The high-temperature conductor printing paste for HTCC ceramic substrates according to claim 1, characterized in that, The particle size of the Al2O3 powder and Y2O3 powder is 0.5 to 2 μm.

6. A method for preparing a high-temperature conductive paste for printing on an HTCC ceramic substrate according to any one of claims 1 to 5, characterized in that, According to the weight percentage of the slurry, Al2O3 powder and Y2O3 powder are mixed with 1 / 5 to 1 / 4 of the organic carrier and then rolled evenly with a three-roll mill to obtain a paste intermediate; the paste intermediate, vermiculite powder, remaining organic carrier, and tungsten powder are mixed and rolled with a three-roll mill to a fineness of less than 10 μm.

7. The method for preparing the printing high-temperature conductor paste for HTCC ceramic substrates according to claim 6, characterized in that, According to the weight percentage of the organic carrier: 12%–18% ethyl cellulose, 1%–3% polyamide wax powder, 0.5%–1% soybean lecithin, 45%–65% terpineol, and 20%–35% dodecyl alcohol, terpineol and dodecyl alcohol are mixed, and ethyl cellulose is added while heating and stirring. After stirring evenly, polyamide wax powder and soybean lecithin are added and stirred until the solution is homogeneous and stable. After cooling, the organic carrier is obtained.

8. The method for preparing the printing high-temperature conductor paste for HTCC ceramic substrates according to claim 7, characterized in that, The heating and stirring temperature is set to 65-85℃, and the stirring speed is 600-1000 r / min.

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