Low temperature co-fired non-ruthenium embedded resistor paste and method of making same

Abstract

This invention belongs to the field of electronic materials technology, specifically relating to a low-temperature co-fired non-ruthenium-based embedded resistor paste and its preparation method. This invention utilizes non-ruthenium-based La... 0.5 Sr 0.5 Co 0.96 Ni 0.04 O3 or La 0.5 Sr 0.5 Co 0.94 Nb 0.06 O3 ceramic, as the conductive phase, reduces material costs and avoids the high-temperature oxidation drawbacks of traditional metal materials. Combined with Bi2O3-B2O3-SiO2-ZnO and Li2O-Bi2O3-B2O3-SiO2+TiO2 as inorganic binder phases, and further supplemented with an organic carrier, a non-ruthenium-based resistive paste is constructed. Embedded resistors prepared using this resistive paste can be co-fired with multilayer dielectric ceramic green tape (dielectric constant ≤ 8) at 925℃. After sintering, the matching performance is good, with no obvious warping or delamination, demonstrating good process adaptability. The resistors can be embedded and integrated into multilayer ceramic circuit boards using LTCC technology. This invention features low cost and high performance, providing a foundation for the embedded integration of resistive elements into multilayer ceramic substrates.

Description

Technical Field

[0001] This invention belongs to the field of electronic materials technology, specifically relating to a non-ruthenium-based embedded resistor paste that can be co-fired at low temperatures and its preparation method, which enables the embedded co-firing process of resistors in multilayer ceramic circuit boards. Background Technology

[0002] Traditional thick-film resistors are formed by printing and sintering resistor paste on relatively inert ceramic substrates such as Al2O3 and AlN. Embedded resistors, on the other hand, are formed by printing resistor paste onto flexible, non-dense green ceramic films, then stacking multiple layers and co-firing them. In contrast, the latter can utilize low-temperature co-firing (LTCC) technology to integrate surface-mount resistor elements into the substrate, thereby further enhancing the functionality of the resistor device while reducing its size, lowering production costs, and improving reliability.

[0003] Generally, achieving embedded resistors requires numerous formulation requirements: such as high bonding strength with ceramics, sintering shrinkage characteristics matching those of the green ceramic film, and no chemical reaction at the co-firing interface with the ceramic. Therefore, current industry research on embedded resistor pastes for multilayer ceramic substrates is relatively limited, with most studies focusing on the more expensive ruthenium-based resistor pastes. This is primarily due to their high conductivity and low sintering temperature, typically around 850℃, allowing for co-firing with glass systems. Major manufacturers include Xi'an Hongxing, DuPont (USA), and Ferro.

[0004] With the rapid development of high-frequency miniaturization and integration of electronic systems, a single chip in an LTCC integrated module often needs to be equipped with hundreds of embedded resistors. Therefore, there is an urgent need to develop non-ruthenium-based, high-performance, and low-cost thick-film resistor pastes to achieve embedded integration of resistors in multilayer ceramic substrates. Summary of the Invention

[0005] To address the aforementioned problems and shortcomings, and to resolve the issue of cost and performance trade-offs in existing embedded integrated resistor elements, this invention provides a low-temperature co-fired non-ruthenium-based embedded resistor paste and its preparation method, using doped and modified La... 0.5 Sr 0.5 Co 0.96 Ni 0.04 O3(O4LSCNi) or La 0.5 Sr 0.5 Co 0.94 Nb 0.06O3(O6LSCNb) ceramic is used as the conductive phase material. By adding suitable glass powder B (Bi2O3-B2O3-SiO2-ZnO) or glass powder A (Li2O-Bi2O3-B2O3-SiO2) + TiO2 as the inorganic binder phase and an organic carrier, a low-cost non-ruthenium-based resistive paste is obtained. This resistive paste exhibits good process adaptability when co-fired with multilayer low-dielectric microwave ceramic green ceramic tape at 925℃. The resistor can be embedded and integrated into the multilayer ceramic circuit board using low-temperature co-fired ceramic technology (LTCC).

[0006] A non-ruthenium-based embedded resistive slurry that can be co-fired at low temperatures is composed of a conductive phase material, an inorganic binder phase, and an organic carrier.

[0007] The conductive phase material is La. 0.5 Sr 0.5 Co 0.96 Ni 0.04 O3 (04LSCNi) ceramic powder, with a suitable inorganic binder phase of Li2O-Bi2O3-B2O3-SiO2 glass powder A+TiO2. By mass ratio, the conductive phase is 90%-95%, the inorganic binder phase is 3%-7% glass powder A and 2%-6% TiO2, with a total mass of 1.

[0008] Alternatively, the conductive phase material is La. 0.5 Sr 0.5 Co 0.94 Nb 0.06 O3(06LSCNb) ceramic powder, with Bi2O3-B2O3-SiO2-ZnO glass powder B as the suitable inorganic binder phase. By mass ratio, the conductive phase is 95%-98%, the inorganic binder phase glass powder B is 2%-5%, and the total amount is 1.

[0009] The organic carrier comprises: solvent, thickener, surfactant, thixotropic agent and leveling agent; by mass ratio, the solvent is 90%-95%, the thickener is 6%-7%, the surfactant is 0.3%-0.6%, the thixotropic agent is 0.8%-1.2%, the leveling agent is 0.3%-0.6%, and the total amount is 1.

[0010] Furthermore, the solvent is terpineol, dibutyl phthalate, and tributyl citrate.

[0011] Furthermore, the thickener is ethyl cellulose, nitrocellulose, or acrylic resin.

[0012] Furthermore, the surfactant is lecithin, toluene, or ethanol.

[0013] Furthermore, the thixotropic agent is hydrogenated castor oil, polyamide wax, or organobentonite.

[0014] A method for preparing a low-temperature co-fired non-ruthenium-based embedded resistor paste includes the following steps:

[0015] Step 1: Prepare materials

[0016] Preparation of the mixture: The conductive phase powder and the inorganic binder phase powder are uniformly mixed according to the composition mass ratio to obtain the mixture. By mass ratio: when 06LSCNb is used as the conductive phase, the conductive phase is 95%-98%, the inorganic binder phase glass powder B is 2%-5%, and the total is 1; when 04LSCNi is used as the conductive phase, the conductive phase is 90%-95%, the inorganic binder phase glass powder A is 3%-7%, TiO2 is 2%-6%, and the total is 1.

[0017] Preparation of the organic carrier: First, weigh the solvent and thickener into a container and heat and stir in a water bath until the thickener is completely dissolved; then add the surfactant, thixotropic agent, and leveling agent, mix evenly, cool, and bottle for later use. By mass ratio, the components are: solvent 90%-95%, thickener 6%-7%, surfactant 0.3%-0.6%, thixotropic agent 0.8%-1.2%, leveling agent 0.3%-0.6%, and the total amount is 1.

[0018] Step 2, Preparation of resistive paste: By mass ratio, 60%-80% of the mixture and 20%-40% of the organic carrier are dispersed evenly to obtain resistive paste.

[0019] This invention uses non-ruthenium-based La 0.5 Sr 0.5 Co 0.96 Ni 0.04 O3(O4LSCNi) or La 0.5 Sr 0.5 Co 0.94 Nb 0.06 O3 (O6LSCNb) ceramic, used as the conductive phase, not only significantly reduces material costs but also avoids the high-temperature oxidation drawbacks of traditional metal materials. Combined with suitable glass powders B (Bi2O3-B2O3-SiO2-ZnO) and A (Li2O-Bi2O3-B2O3-SiO2) + TiO2 as inorganic binders, these phases are chemically compatible with the composite conductive phase. An organic carrier is then used to construct a non-ruthenium-based resistive paste. Embedded resistors prepared using this resistive paste exhibit good matching after sintering, with no significant warping or delamination. Further experimental data verify that the non-ruthenium-based low-cost resistive paste provided by this invention can be co-fired with multilayer dielectric ceramic green tape (dielectric constant ≤ 8) at 925℃, exhibiting good process adaptability. The resistors can be embedded and integrated into multilayer ceramic circuit boards using low-temperature co-fired ceramic technology (LTCC).

[0020] In summary, this invention provides a non-ruthenium-based embedded resistor paste that features low cost and high performance, providing a foundation for the embedded integration of resistor elements in multilayer ceramic substrates. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the preparation process of the resistive paste of the present invention.

[0022] Figure 2 This is a three-dimensional perspective view of the embedded resistor structure in an embodiment.

[0023] Figure 3 The images are scanning electron microscope (SEM) images of the wafers sintered after being numbered 1 and 2 in Table 1 of the examples.

[0024] Figure 4 The cross-sectional view and line EDS test of the embedded resistor prepared by the slurry obtained in the example are shown.

[0025] Figure reference numerals: 1-resistive layer, 2-silver electrode, 3-dielectric ceramic. Detailed Implementation

[0026] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings:

[0027] This invention provides a low-temperature co-fired non-ruthenium-based embedded resistor paste and its preparation method, using doped and modified La 0.5 Sr 0.5 Co 0.96 Ni 0.04 O3(O4LSCNi) or La 0.5 Sr 0.5 Co 0.94 Nb 0.06 O3(06LSCNb) ceramic is used as the conductive phase material. By adding suitable glass powder B (Bi2O3-B2O3-SiO2-ZnO) or glass powder A (Li2O-Bi2O3-B2O3-SiO2) + TiO2 as the inorganic binder phase and an organic carrier, a low-cost, non-ruthenium-based resistive paste is obtained. This resistive paste exhibits good process adaptability when co-fired with multilayer low-dielectric microwave ceramic green ceramic tape at 925℃. Resistor integration within multilayer ceramic circuit boards can be achieved through low-temperature co-fired ceramic technology (LTCC). The resistive paste fabrication process is as follows: Figure 1 As shown, the specific steps are as follows:

[0028] Step 1, Preparation of the mixture: The composite conductive phase powder and the inorganic binder phase powder are mixed evenly according to the composition mass ratio; in the example, La is selected respectively. 0.5 Sr 0.5 Co 0.96 Ni 0.04O3(O4LSCNi) or La 0.5 Sr 0.5 Co 0.94 Nb 0.06 O3(06LSCNb) ceramic fractions are used as composite conductive phases to reduce material costs and avoid the disadvantage of traditional metal materials being easily oxidized at high temperatures.

[0029] Glass powder B (Bi2O3-B2O3-SiO2-ZnO) and glass powder A (Li2O-Bi2O3-B2O3-SiO2) + TiO2, which are compatible with the conductive phase, are selected as inorganic binder phases to achieve chemical compatibility with the composite conductive phase.

[0030] Table 1: Powder composition ratio of conductive phase and inorganic binder phase in each embodiment

[0031]

[0032] Formulas 1 and 2 were ball-milled for 6 hours, dried, and then 5 wt.% PVA was added, granulated, and pressed into discs. The discs were then sintered in air at 925°C for 3 hours. The sintered discs were then examined using a scanning electron microscope (SEM). Figure 3 As shown, where Figure 3 (a) is sample number 2. Figure 3 (b) Sample No. 1. Furthermore, room temperature conductivity tests were performed on the samples sintered with the binder phase. The conductivity of the 04LSCNi sample decreased to 191 S / cm (5.2 mΩ·cm), and that of the 06LSCNb sample decreased to 357 S / cm (2.8 mΩ·cm). Due to the relatively low intrinsic conductivity of glass powder and TiO2, the conductivity decrease of both conductive materials was significant, but they still exhibited good conductivity. In summary, glass powder A + TiO2 is chemically compatible with 04LSCNi ceramics, and glass powder B is also chemically compatible with 06LSCNb ceramics, and both can be used as binder phases in slurry preparation.

[0033] Preparation of the organic carrier: Solvent and thickener were placed in a flask, then heated and stirred in a 90°C water bath until the thickener was completely dissolved. Surfactant, thixotropic agent, and leveling agent were then added, stirred again until homogeneous, cooled, and bottled for later use. By mass ratio: solvent 90%-95%, thickener 6%-7%, surfactant 0.3%-0.6%, thixotropic agent 0.8%-1.2%, leveling agent 0.3%-0.6%, total 1. In this embodiment, terpineol, dibutyl phthalate, and tributyl citrate were used as organic solvents, ethyl cellulose as a thickener, lecithin as a surfactant, and hydrogenated castor oil as a thixotropic agent.

[0034] Step 2, Preparation of resistive slurry: The mixed composite conductive phase powder and inorganic binder phase powder (mixture) are mixed with an organic carrier, dispersed by stirring, and rolled by three rollers to prepare resistive slurry; in the example, the mass ratio of mixture to organic carrier is 7:3.

[0035] Step 3, Preparation of the embedded resistor, using... Figure 2 The embedded resistor structure is shown.

[0036] First, silver electrodes are printed on the green ceramic film, and after drying, a resistor layer is printed. Then, the green ceramic film is stacked and isostatically pressed. Finally, the embedded resistors obtained by cutting are heat-preserved at 450℃ for debinding and sintered in air at 925℃ for 3 hours.

[0037] In this embodiment, a 325-mesh nylon screen is used for printing resistors, and the screen is printed four times. After printing, the screen is placed on a horizontal platform for leveling for 15 minutes. The green ceramic diaphragm is subjected to isostatic pressing at a temperature of 70°C, a pressure of 20 MPa, and a holding time of 30 minutes.

[0038] The embedded resistor prepared by the above method includes: a resistive layer (1), a silver electrode (2), and a dielectric ceramic (3); a 0.5 mm overlap area is maintained between the resistive layer (1) and the silver electrode (2); a 0.5 mm blank area is maintained on both the left and right sides of the resistive layer (1) and the dielectric ceramic (3); the length and width L*W of the resistor are 5.0 mm × 2.5 mm.

[0039] Embedded resistors prepared using slurries No. 1, No. 5, and Ferro's FX87-103 (10kΩ / □) embedded co-fired resistor slurry were subjected to linear EDS scanning. The test cross-sections and results are shown below. Figure 4 As shown, (4-6) correspond to sample number 1, (7-9) correspond to sample number 5, and (10-12) correspond to FX87-103. Visually, the resistive layer has straight lines and no cracks. Figure 4 (6) and Figure 4 (9) It can be observed that elements such as La, Sr, Co, and Nb (or Ni) exhibit significant skipping at the interface and do not diffuse into the dielectric ceramic; from Figure 4 (12) It can be found that the transition of Ru element at the interface is also obvious. The above experimental data shows that the resistive paste used in this invention is stable during the sintering process and is compatible with the green ceramic film used.

[0040] Embedded resistors were prepared using slurry numbers 1, 3, and 5. Five embedded resistors were randomly selected from each prepared resistor for testing and comparison.

[0041] Table 2: Shear resistance and TCR of embedded resistors

[0042]

[0043]

[0044] As shown in Table 2, with the increase of inorganic binder phase, the TCR of the resistance changes from positive to negative, and the sheet resistance can increase from tens of Ω / □ to tens of kΩ / □. The sheet resistance range is relatively wide, and the sheet resistance test deviation is within ±31% of the intermediate resistance value. This proves that the embedded resistor paste provided by the present invention can ensure the excellent performance of the embedded resistor after sintering.

[0045] As can be seen from the above embodiments, this invention uses non-ruthenium-based 04LSCNi or 06LSCNb ceramics as the conductive phase, which not only greatly reduces material costs but also avoids the disadvantage of easy oxidation at high temperatures of traditional metal materials. Combined with suitable glass powder B (Bi2O3-B2O3-SiO2-ZnO) and glass powder A (Li2O-Bi2O3-B2O3-SiO2) + TiO2 as inorganic binder phases, they are chemically compatible with the composite conductive phase. Furthermore, an organic carrier is added to form a non-ruthenium-based resistive paste. Embedded resistors prepared using this resistive paste can be co-fired with multilayer dielectric ceramic green ceramic tapes (dielectric constant ≤ 8) at 925℃. After sintering, the matching performance is good, with no obvious warping or delamination, demonstrating good process adaptability. The embedded integration of resistors in multilayer ceramic circuit boards can be achieved through low-temperature co-firing (LTCC) technology. This invention features low cost and high performance, providing a foundation for the embedded integration of resistive elements in multilayer ceramic substrates.

Claims

1. A non-ruthenium-based internally embedded resistive slurry capable of low-temperature co-firing, characterized in that: It consists of a conductive phase material, an inorganic binder phase, and an organic carrier, wherein the organic carrier accounts for 20%-40% of the mass, and the total mass is 1. The conductive phase material is La. 0.5 Sr 0.5 Co 0.96 Ni 0.04 O3 ceramic powder, the suitable inorganic binder phase is Li2O-Bi2O3-B2O3-SiO2 glass powder A+TiO2; by mass ratio, the conductive phase is 90%-95%, the inorganic binder phase is 3%-7% glass powder A, 2%-6% TiO2, and the total amount is 1. Alternatively, the conductive phase material is La. 0.5 Sr 0.5 Co 0.94 Nb 0.06 O3 ceramic powder, with Bi2O3-B2O3-SiO2-ZnO glass powder B as the suitable inorganic binder phase; by mass ratio, the conductive phase is 95%-98%, the inorganic binder phase glass powder B is 2%-5%, and the total amount is 1. The organic carrier comprises: solvent, thickener, surfactant, thixotropic agent and leveling agent; by mass ratio, the solvent is 90%-95%, the thickener is 6%-7%, the surfactant is 0.3%-0.6%, the thixotropic agent is 0.8%-1.2%, the leveling agent is 0.3%-0.6%, and the total amount is 1.

2. The low-temperature co-fired non-ruthenium-based embedded resistance paste as described in claim 1, characterized in that: The solvent is terpineol, dibutyl phthalate, and tributyl citrate.

3. The low-temperature co-fired non-ruthenium-based embedded resistance paste as described in claim 1, characterized in that: The thickener is ethyl cellulose, nitrocellulose, or acrylic resin.

4. The low-temperature co-fired non-ruthenium-based embedded resistance paste as described in claim 1, characterized in that: The surfactant is lecithin, toluene, or ethanol.

5. The low-temperature co-fired non-ruthenium-based embedded resistance paste as described in claim 1, characterized in that: The thixotropic agent is hydrogenated castor oil, polyamide wax, or organobentonite.

6. The method for preparing the low-temperature co-fired non-ruthenium-based embedded resistor paste as described in claim 1, characterized in that, Includes the following steps: Step 1: Prepare materials Preparation of the mixture: The conductive phase material powder and the inorganic binder phase powder are uniformly mixed according to the composition mass ratio to obtain the mixture; by mass ratio: when La 0.5 Sr 0.5 Co 0.94 Nb 0.06 When O3 is used as the conductive phase, the conductive phase accounts for 95%-98%, and the inorganic binder phase, glass powder B, accounts for 2%-5%, with a total amount of 1%; La 0.5 Sr 0.5 Co 0.96 Ni 0.04 When O3 is used as the conductive phase, the conductive phase accounts for 90%-95%, and the inorganic binder phase consists of 3%-7% glass powder A, 2%-6% TiO2, and a total of 1%. Preparation of organic carrier: First, weigh the solvent and thickener into a container and heat and stir in a water bath until the thickener is completely dissolved; then add the surfactant, thixotropic agent and leveling agent, mix evenly, cool and bottle for later use; by mass ratio, the solvent is 90%-95%, the thickener is 6%-7%, the surfactant is 0.3%-0.6%, the thixotropic agent is 0.8%-1.2%, the leveling agent is 0.3%-0.6%, and the total amount is 1. Step 2, Preparation of resistive paste: By mass ratio, 60%-80% of the mixture and 20%-40% of the organic carrier are dispersed evenly to obtain resistive paste.

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