Low-temperature curing slurry for thick film hybrid circuit and preparation method of low-temperature curing slurry

Abstract

The invention discloses low-temperature curing slurry for a thick film hybrid circuit and a preparation method of the low-temperature curing slurry, and relates to the technical field of electronic slurry. Wherein the organic carrier comprises 35 to 55 weight percent of thermosetting resin and 45 to 65 weight percent of solvent; the thermosetting resin comprises at least two of epoxy resin, modified epoxy resin and organosilicon modified polyester resin, the epoxy resin is bisphenol A type solid resin, and the modified epoxy resin is an alkoxy siloxane modified product with an epoxy functional group. According to the invention, at least two of epoxy resin, modified epoxy resin and organosilicon modified polyester resin are adopted as matrix resin, the epoxy resin is bisphenol A type solid resin, a body network structure is formed after curing and crosslinking, the crosslinking density is high, the modified epoxy resin is an alkoxy siloxane modified product with an epoxy functional group, and the curing strength is high. Alkoxy siloxane contained in the resin can improve the adhesive force in the curing process, and in addition, the leveling property of the slurry can be improved.

Description

Technical Field

[0001] This invention relates to the field of electronic paste technology, specifically to a low-temperature curing paste for thick-film hybrid circuits and its preparation method. Background Technology

[0002] Electronic paste, as a fundamental material for electronic components, is a core component that determines the final performance of electronic products. Electronic components and modules are increasingly developing towards higher integration, miniaturization, and surface-mount technology, especially in applications such as 5G communication and intelligent transportation, which require even smaller, more precise, and more reliable surface-mount components. Thick-film surface-mount resistors are one of the components in electronic products, widely used in automotive electronics, LED lighting, new energy, and consumer electronics. Their performance and size directly affect the functionality and dimensions of electronic products.

[0003] The encapsulation layer of a chip resistor protects the core functional resistive layer. Therefore, the performance of the insulating dielectric encapsulation paste plays a crucial role in the long-term performance and stability of the chip resistor. The secondary encapsulation paste, as the outermost protective film of the chip resistor, overlaps with the alumina substrate layer, electrode layer, and glass encapsulation layer. Its basic application characteristics include printability, insulation, and breakdown voltage withstand capability. These are the fundamental properties of the secondary encapsulation paste, and their quality significantly impacts the manufacturing and operational stability of the chip resistor.

[0004] Existing low-temperature curing pastes for thick-film hybrid circuits use epoxy resin as the main resin and acid anhydrides and aliphatic polyamines as the curing agents, which has some shortcomings. First, the printability is poor, and local non-leveling or edge expansion may occur; second, the insulation performance and breakdown voltage withstand capability need to be improved; finally, the room temperature storage period is short, and most require low-temperature storage.

[0005] In view of the above, this application is hereby submitted. Summary of the Invention

[0006] The purpose of this invention is to provide a low-temperature curing slurry for thick-film hybrid circuits and its preparation method. By setting at least two of epoxy resin, modified epoxy resin, and silicone-modified polyester resin as the main resin in an organic carrier, the problem of local non-leveling or edge expansion occurs when epoxy resin is used as the main resin in existing slurries is solved.

[0007] First, embodiments of the present invention provide a low-temperature curing paste for thick-film hybrid circuits, comprising a mixture of the following raw materials by weight percentage: 30%~50% solid filler, 30%~50% organic carrier, 3%~15% crosslinking curing agent and 5%~10% functional additives; The organic carrier comprises 35-55 wt% thermosetting resin and 45-65 wt% solvent; The thermosetting resin includes at least two of epoxy resin, modified epoxy resin, and silicone-modified polyester resin, wherein the epoxy resin is a bisphenol A type solid resin, and the modified epoxy resin is an alkoxysiloxane modified product with epoxy functional groups.

[0008] The organosilicon-modified polyester resin is produced by introducing organosilicon into polyester segments through block copolymerization or grafting reaction, containing Si-O bonds, which significantly improves heat resistance.

[0009] As an optional embodiment, the thermosetting resin includes epoxy resin and modified epoxy resin, wherein the epoxy equivalent of the epoxy resin is 500~2000, and the preferred ratio of epoxy resin and modified epoxy resin is 9~19:1. The modified epoxy resin is preferably an organosilicon chemically modified bisphenol A type solid resin, the purpose of which is to improve the leveling of the slurry and the adhesion after curing.

[0010] As an alternative implementation, the solid filler includes micron-sized silica, hydrophobic fumed silica, kaolin, and black pigment.

[0011] As an optional implementation, the micron-sized silica accounts for 20% to 40% of the weight of the slurry, the hydrophobic fumed silica accounts for 0.5% to 2% of the weight of the slurry, the kaolin accounts for 5% to 15% of the weight of the slurry, and the black pigment accounts for 3% to 10% of the weight of the slurry.

[0012] As an optional implementation, the micron-sized silica is spherical electronic-grade silica with a particle size of 2-5 μm; the surface of the hydrophobic fumed silica is treated with polydimethylsiloxane, resulting in a specific surface area of ​​100-180 m². 2 / g.

[0013] As an optional implementation, the kaolin is calcined kaolin with a particle size of 1~5 μm; the black pigment is any one or more of iron oxide black, iron chromium black, and manganese iron black with a particle size of 1~10 μm.

[0014] As an optional implementation, the solvent includes at least one of ester solvents, ether solvents, alcohol solvents, and alcohol ester solvents.

[0015] As an optional implementation, the crosslinking curing agent includes at least one of diaminodiphenyl sulfone, diaminodiphenylmethane, m-phenylenediamine, isophorone diamine, and N-aminoethylpiperazine.

[0016] As an optional implementation, the functional additive includes at least one of a dispersant, a defoamer, and a leveling agent.

[0017] Secondly, this invention also provides a method for preparing a low-temperature curing paste for thick-film hybrid circuits, comprising the following steps: S1: Dissolve thermosetting resin in a solvent and stir to prepare an organic carrier; S2: Mix the organic carrier, solid filler, crosslinking curing agent and functional additives to obtain a preparative slurry; S3: The prepared slurry is ground, dispersed, filtered, and degassed to obtain a low-temperature curing slurry for thick film hybrid circuits.

[0018] Compared with the prior art, the embodiments of the present invention have the following advantages and beneficial effects: 1. In the embodiments of the present invention, at least two of epoxy resin, modified epoxy resin, and silicone-modified polyester resin are used as the main resin. The epoxy resin is a bisphenol A type solid resin with an epoxy equivalent of 500~2000. After curing and crosslinking, it forms a three-dimensional network structure with high crosslinking density. The modified epoxy resin is an alkoxysiloxane modified product with epoxy functional groups. The alkoxysiloxane contained in the resin can improve the adhesion during the curing process and also improve the leveling of the slurry.

[0019] 2. In the embodiments of the present invention, at least two of epoxy resin, modified epoxy resin, and silicone-modified polyester resin are used as the main resin, and aromatic and alicyclic polyamines and other high-temperature curing agents are used as crosslinking curing agents. The room temperature shelf life of the slurry can reach more than 3 months. After the product is cured, there are no by-products, and the insulation resistivity is increased by an order of magnitude, which is beneficial to the performance stability of the chip resistor.

[0020] 3. In this embodiment of the invention, the micron-sized spherical silica in the slurry can improve the heat resistance and insulation performance of the protective layer, while the hydrophobic fumed silica can improve the thixotropy and printability of the slurry. Furthermore, the silanol groups on its surface can improve the dispersibility of the amine crosslinking curing agent in the slurry, resulting in more uniform and thorough crosslinking and curing. The slurry of this embodiment is suitable for secondary encapsulation or marking printing of chip resistors. After curing, the slurry forms a dense protective layer on the surface of the chip resistor, effectively protecting it from external moisture and acid / alkali corrosion. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a microscope image of the cured film of the slurry in Example 2; Figure 2 This is a microscope image of the cured film of the slurry in Comparative Example 2. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of this invention, it should be noted that the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Example

[0027] This invention provides a method for preparing a low-temperature curing paste for thick-film hybrid circuits, comprising the following: I. Raw material ratio (based on 100% of total weight) (1) Solid filler: 30%~50% Micron-sized silica (spherical electronic grade, particle size 2~5µm): 20%~40%; Hydrophobic fumed silica (surface treated with polydimethylsiloxane, specific surface area 100~180m²) 2 / g): 0.5%~2%; Kaolin (calcined kaolin, particle size 1~5um): 5%~15%; Black pigment (any one or more of iron oxide black, iron chromium black, and manganese iron black, with a particle size of 1~10um): 3%~10%.

[0028] (2) Organic carrier: 30%~50% Thermosetting resin: 35%~55% At least two of the following: bisphenol A type solid epoxy resin (epoxy equivalent 500~2000), alkoxysiloxane modified epoxy resin with epoxy functional group, and organosilicon modified polyester resin. Solvent: 45%~65% At least one of the following: ester solvents (such as ethyl acetate, butyl acetate, etc.), ether solvents (such as ethylene glycol ether, propylene glycol ether, etc.), alcohol solvents (such as ethanol, isopropanol, etc.), and alcohol ester solvents (such as ethylene glycol ethyl ether acetate, etc.).

[0029] (3) Crosslinking curing agent: 3%~15% At least one of diaminodiphenyl sulfone, diaminodiphenylmethane, m-phenylenediamine, isophorone diamine, and N-aminoethylpiperazine.

[0030] (4) Functional additives: 5%~10% At least one of the following: dispersant (such as polyphosphate dispersant, polycarboxylate dispersant, etc.), defoamer (such as polysiloxane defoamer, polyether defoamer, etc.), and leveling agent (such as silicone leveling agent, acrylic leveling agent, etc.).

[0031] II. Preparation Steps (1) Preparation of organic carriers Weigh the thermosetting resin and solvent according to the mixing ratio; Add the weighed resin to the solvent and stir evenly using a high-speed stirrer (1000~2000 rpm) for 30~60 minutes to ensure that the resin is completely dissolved and a uniform organic carrier is obtained.

[0032] (2) Pretreatment of solid fillers Weigh out the micron-sized silica, hydrophobic fumed silica, kaolin, and black pigment according to the specified ratio; Add the weighed solid filler to a high-speed mixer and pre-mix for 5-10 minutes to ensure the filler is initially and evenly mixed.

[0033] (3) Mixing of slurry The prepared organic carrier is added to the pretreated solid filler; Weigh and add the crosslinking curing agent and functional additives according to the mixing ratio; Add the above mixture to the mixer and stir evenly using a high-speed mixer (1000~2000 rpm) for 60~120 minutes to ensure that all components are fully mixed. To avoid rapid heating of the material under high-speed stirring, the jacket of the material tank is cooled by circulating water.

[0034] (4) Grinding, dispersing and filtering Transfer the well-stirred slurry mixture to a grinding device for grinding and dispersion treatment. The grinding time is 30-60 minutes to ensure that the filler particles are evenly dispersed. The ground slurry is filtered through a filtration device (filtration accuracy 1~5um) to remove large particulate impurities and ensure the uniformity and fineness of the slurry.

[0035] (5) Defoaming treatment The filtered slurry is transferred to a vacuum degassing device for degassing treatment. The vacuum degree is controlled at -0.08 to -0.1 MPa, and the degassing time is 10 to 30 minutes to ensure that there are no air bubbles in the slurry.

[0036] (6) Preparation of finished slurry The degassed slurry is packaged to obtain the finished product of low-temperature curing slurry for thick film hybrid circuits.

[0037] Example 1: This embodiment of the invention provides a method for preparing a low-temperature curing paste for thick-film hybrid circuits, comprising the following: I. Raw material ratio (based on 100% of total weight) (1) Solid filler: 49% Micron-sized silica (spherical electronic grade, particle size 2~5µm): 35%; Hydrophobic fumed silica (surface treated with polydimethylsiloxane, specific surface area 100~180m²) 2 / g): 0.5%; Kaolin (calcined kaolin, particle size 1~5um): 8.5%; Black pigment (any one or more of iron oxide black, iron chromium black, and manganese iron black, with a particle size of 1~10um): 5%.

[0038] (2) Organic carrier: 40% Thermosetting resin: 45% 40% bisphenol A type solid epoxy resin (epoxy equivalent 500~2000), 5% alkoxysiloxane modified epoxy resin with epoxy functional groups and 0% organosilicon modified polyester resin. Solvent: 55% Ethyl acetate was selected.

[0039] (3) Crosslinking curing agent: 6% Diaminodiphenyl sulfone was selected.

[0040] (4) Functional additives: 5% A mixture of polyphosphate dispersants, polysiloxane defoamers, and organosilicon leveling agents.

[0041] II. Preparation Steps (1) Preparation of organic carriers Weigh the thermosetting resin and solvent according to the mixing ratio; Add the weighed resin to the solvent and stir evenly using a high-speed stirrer (1500 rpm) for 45 minutes to ensure that the resin is completely dissolved and a uniform organic carrier is obtained.

[0042] (2) Pretreatment of solid fillers Weigh out the micron-sized silica, hydrophobic fumed silica, kaolin, and black pigment according to the specified ratio; Add the weighed solid filler to the high-speed mixer and pre-mix for 8 minutes to make the filler initially uniform.

[0043] (3) Mixing of slurry The prepared organic carrier is added to the pretreated solid filler; Weigh and add the crosslinking curing agent and functional additives according to the mixing ratio; Add the above mixture to the mixer and stir evenly using a high-speed mixer (1500 rpm) for 90 minutes to ensure that all components are fully mixed. To avoid rapid heating of the material under high-speed stirring, the jacket of the material tank is cooled by circulating water.

[0044] (4) Grinding, dispersing and filtering Transfer the well-stirred slurry mixture to a grinding device for grinding and dispersion treatment for 50 minutes to ensure uniform dispersion of filler particles; The ground slurry is filtered through a filtration device (filtration accuracy 1~5um) to remove large particulate impurities and ensure the uniformity and fineness of the slurry.

[0045] (5) Defoaming treatment The filtered slurry is transferred to a vacuum degassing device for degassing treatment. The vacuum degree is controlled at -0.08 to -0.1 MPa, and the degassing time is 20 minutes to ensure that there are no air bubbles in the slurry.

[0046] (6) Preparation of finished slurry The degassed slurry is packaged to obtain the finished product of low-temperature curing slurry for thick film hybrid circuits.

[0047] Example 2: This embodiment of the invention provides a method for preparing a low-temperature curing paste for thick-film hybrid circuits, comprising the following: I. Raw material ratio (based on 100% of total weight) (1) Solid filler: 49% Micron-sized silica (spherical electronic grade, particle size 2~5µm): 35%; Hydrophobic fumed silica (surface treated with polydimethylsiloxane, specific surface area 100~180m²)2 / g): 1%; Kaolin (calcined kaolin, particle size 1~5um): 8%; Black pigment (any one or more of iron oxide black, iron chromium black, and manganese iron black, with a particle size of 1~10um): 5%.

[0048] (2) Organic carrier: 40% Thermosetting resin: 45% 30% bisphenol A type solid epoxy resin (epoxy equivalent 500~2000), 10% alkoxysiloxane modified epoxy resin with epoxy functional groups and 5% organosilicon modified polyester resin. Solvent: 55% A mixture of ethyl acetate and ethanol is selected.

[0049] (3) Crosslinking curing agent: 6% A mixture of diaminodiphenylmethane and m-phenylenediamine was selected.

[0050] (4) Functional additives: 5% A mixture of polycarboxylate dispersants and polysiloxane defoamers.

[0051] II. Preparation Steps (1) Preparation of organic carriers Weigh the thermosetting resin and solvent according to the mixing ratio; Add the weighed resin to the solvent and stir evenly using a high-speed stirrer (1000 rpm) for 60 minutes to ensure that the resin is completely dissolved and a uniform organic carrier is obtained.

[0052] (2) Pretreatment of solid fillers Weigh out the micron-sized silica, hydrophobic fumed silica, kaolin, and black pigment according to the specified ratio; Add the weighed solid filler to the high-speed mixer and pre-mix for 5 minutes to make the filler initially uniform.

[0053] (3) Mixing of slurry The prepared organic carrier is added to the pretreated solid filler; Weigh and add the crosslinking curing agent and functional additives according to the mixing ratio; Add the above mixture to the mixer and stir evenly using a high-speed mixer (1000 rpm) for 120 minutes to ensure that all components are fully mixed. To avoid rapid heating of the material under high-speed stirring, the jacket of the material tank is cooled by circulating water.

[0054] (4) Grinding, dispersing and filtering Transfer the well-stirred slurry mixture to a grinding device for grinding and dispersion treatment for 30 minutes to ensure uniform dispersion of filler particles; The ground slurry is filtered through a filtration device (filtration accuracy 1~5um) to remove large particulate impurities and ensure the uniformity and fineness of the slurry.

[0055] (5) Defoaming treatment The filtered slurry is transferred to a vacuum degassing device for degassing treatment. The vacuum degree is controlled at -0.08 to -0.1 MPa, and the degassing time is 10 minutes to ensure that there are no air bubbles in the slurry.

[0056] (6) Preparation of finished slurry The degassed slurry is packaged to obtain the finished product of low-temperature curing slurry for thick film hybrid circuits.

[0057] Example 3: This embodiment of the invention provides a method for preparing a low-temperature curing paste for thick-film hybrid circuits, comprising the following: I. Raw material ratio (based on 100% of total weight) (1) Solid filler: 49% Micron-sized silica (spherical electronic grade, particle size 2~5µm): 35%; Hydrophobic fumed silica (surface treated with polydimethylsiloxane, specific surface area 100~180m²) 2 / g): 2%; Kaolin (calcined kaolin, particle size 1~5um): 7%; Black pigment (any one or more of iron oxide black, iron chromium black, and manganese iron black, with a particle size of 1~10um): 5%.

[0058] (2) Organic carrier: 40% Thermosetting resin: 45% 20% bisphenol A type solid epoxy resin (epoxy equivalent 500~2000), 15% alkoxysiloxane modified epoxy resin with epoxy functional groups and 10% organosilicon modified polyester resin. Solvent: 55% Ethanol should be selected.

[0059] (3) Crosslinking curing agent: 6% N-aminoethylpiperazine was selected.

[0060] (4) Functional additives: 5% A mixture of polyphosphate dispersants, polyether defoamers, and acrylic leveling agents.

[0061] II. Preparation Steps (1) Preparation of organic carriers Weigh the thermosetting resin and solvent according to the mixing ratio; Add the weighed resin to the solvent and stir evenly using a high-speed stirrer (2000 rpm) for 30 minutes to ensure that the resin is completely dissolved and a uniform organic carrier is obtained.

[0062] (2) Pretreatment of solid fillers Weigh out the micron-sized silica, hydrophobic fumed silica, kaolin, and black pigment according to the specified ratio; Add the weighed solid filler to the high-speed mixer and pre-mix for 10 minutes to make the filler initially uniform.

[0063] (3) Mixing of slurry The prepared organic carrier is added to the pretreated solid filler; Weigh and add the crosslinking curing agent and functional additives according to the mixing ratio; Add the above mixture to the mixer and stir evenly using a high-speed mixer (2000 rpm) for 60 minutes to ensure that all components are fully mixed. To avoid rapid heating of the material under high-speed stirring, the jacket of the material tank is cooled by circulating water.

[0064] (4) Grinding, dispersing and filtering The well-stirred slurry mixture is transferred to a grinding device for grinding and dispersion treatment for 60 minutes to ensure that the filler particles are evenly dispersed. The ground slurry is filtered through a filtration device (filtration accuracy 1~5um) to remove large particulate impurities and ensure the uniformity and fineness of the slurry.

[0065] (5) Defoaming treatment The filtered slurry is transferred to a vacuum degassing device for degassing treatment. The vacuum degree is controlled at -0.08 to -0.1 MPa, and the degassing time is 30 minutes to ensure that there are no air bubbles in the slurry.

[0066] (6) Preparation of finished slurry The degassed slurry is packaged to obtain the finished product of low-temperature curing slurry for thick film hybrid circuits.

[0067] Comparative Example 5: A method for preparing a cured slurry is provided. The difference from Example 2 is that the epoxy resin is bisphenol F type solid resin, while the other steps and parameters remain unchanged.

[0068] Comparative Example 6: A method for preparing a cured slurry is provided, the difference from Example 2 is that the organosilicon-modified polyester resin is replaced with an epoxy-modified polyester resin, while the other steps remain unchanged.

[0069] The other embodiments and comparative examples differ from those in Example 1 in their formulation, but the remaining process steps are the same. The formulation details are shown in Table 1 and Table 2 below: Table 1 Organic carrier formulations (unit: weight percentage, %)

[0070] Table 2. Slurry Formulation (Unit: weight percentage, %)

[0071] The slurries prepared in Examples 1-8 and Comparative Examples 1-6 were subjected to the following performance tests, and the results are shown in Table 3: (1) Viscosity test: Brookfield DV-Ⅱ type viscometer was used, CP-52 rotor was selected, test temperature (25±2)℃, rotor speed 10 r / min, and the viscosity value corresponding to 1min test time was used.

[0072] (2) Insulation resistance test: Print low-temperature curing paste on the alumina substrate with silver electrodes, let it stand for 5 minutes, dry it at 120℃ for 10 minutes, and then cure it at 190℃ for 50 minutes. Repeat the printing 2 to 3 layers to ensure that the thickness of the cured film is between 30 and 50 μm. Finally, print low-temperature conductive silver paste on the cured film and cure it. Then, use an insulation resistance tester to test it. Set the voltage to 100V. The final stable value displayed after the test starts is the insulation resistance. Generally, the higher the insulation resistance, the better.

[0073] (3) Withstand voltage test: Prepare the sample according to the sample preparation method in test (2), and test it on the withstand voltage tester. The value when the voltage breaks down is the withstand voltage value of the sample.

[0074] (4) Printing appearance: Observe the surface appearance of the cured film by magnifying the sample 30 times under a microscope.

[0075] Table 3 Slurry Performance Tests

[0076] Figure 1 This is a microscope image of the cured film of the slurry in Example 2. Figure 2 This is a microscope image of the cured film of the slurry in Comparative Example 2, by... Figure 1 and 2 The comparison shows that when the slurry formula contains modified epoxy resin, the surface after printing and curing is smooth and flat with no obvious defects, while the surface after printing and curing is uneven without modified epoxy resin.

[0077] Table 3 shows that in Examples 1-3, the viscosity of the slurry increased significantly with the increase of fumed silica addition, indicating that silica, as a thixotropic agent, had a significant impact on the viscosity. Insulation resistivity and withstand voltage increased slightly, and the viscosity increased slightly after 3 months of storage, with the increase in fumed silica addition increasing further. The slurry surface was smooth and defect-free after printing. In Examples 5-7, the insulation resistivity and withstand voltage increased significantly with the increase of thermosetting resin addition, indicating that the amount of thermosetting resin, as the main resin, had a significant impact on the insulation resistivity and withstand voltage. In Comparative Examples 1-4, without modified epoxy resin, the slurry had poor fluidity, and localized pore defects were present during printing. Using alicyclic and aromatic polyamines as curing agents, the curing temperature was higher, and the viscosity of the slurry was relatively stable after 3 months of storage at room temperature. Although the performance of Comparative Example 6 was comparable to that of the Example, the surface turned yellow after curing when the slurry did not contain silicone-modified polyester resin. This was due to the poor heat resistance of the monomer resin. Conversely, it was normal when silicone-modified polyester resin was present, indicating that silicone-modified polyester resin can improve heat resistance under high-temperature curing conditions. The performance test results of Comparative Example 5 showed that when the epoxy resin was bisphenol F type solid resin, the presence of the methylene structure significantly reduced the viscosity of the slurry, resulting in a significantly worse printing appearance.

[0078] By comparing Examples 1-8 and Comparative Examples 1-4, it can be seen that the low-temperature curing paste for thick-film hybrid circuits of the present invention has advantages such as good printability, high insulation resistivity, good voltage resistance, and long room temperature storage period. When used for secondary encapsulation protection of chip resistors, it is more conducive to the production and manufacturing of chip resistors and can improve the stability of chip resistors in use.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention. It should be noted that the structures or components illustrated in the accompanying drawings are not necessarily drawn to scale, and descriptions of well-known components, processing techniques, and processes have been omitted to avoid unnecessarily limiting the invention.

Claims

1. A low temperature curing paste for thick film hybrid circuits, characterized by, A mixture comprising the following raw materials in weight percentage: 30-50% solid filler, 30-50% organic carrier, 3-15% cross-linking curing agent, and 5-10% functional aid; The organic carrier comprises 35-55 wt% thermosetting resin and 45-65 wt% solvent. The thermosetting resin comprises at least two of epoxy resin, modified epoxy resin, and silicone-modified polyester resin, the epoxy resin being bisphenol A type solid resin, and the modified epoxy resin being an alkoxy siloxane modified product with epoxy functional groups.

2. A low temperature cure paste for thick film hybrid circuits according to claim 1, characterized in that, The thermosetting resin comprises epoxy resin and modified epoxy resin, the epoxy equivalent weight of the epoxy resin being 500-2000.

3. A low temperature cure paste for thick film hybrid circuits according to claim 1, wherein, The solid filler comprises micron-sized silica, hydrophobic fumed silica, kaolin, and black pigment.

4. A low temperature cure paste for thick film hybrid circuits according to claim 2, wherein, The micron-sized silica accounts for 20-40% of the weight of the slurry, the hydrophobic fumed silica accounts for 0.5-2% of the weight of the slurry, the kaolin accounts for 5-15% of the weight of the slurry, and the black pigment accounts for 3-10% of the weight of the slurry.

5. A low temperature cure paste for thick film hybrid circuits according to claim 4, wherein, The micron-sized silicon dioxide is spherical electronic-grade silicon dioxide with a particle size of 2-5 um; the surface of the hydrophobic fumed silicon dioxide is treated with polydimethylsiloxane, and the specific surface area is 100-180 m 2 / g.

6. A low temperature cure paste for thick film hybrid circuits according to claim 4, wherein, The kaolin is calcined kaolin with a particle size of 1-5 um, and the black pigment is any one or mixture of iron oxide black, iron-chromium black, and manganese-iron black with a particle size of 1-10 um.

7. A low temperature cure paste for thick film hybrid circuits according to claim 1 wherein, The solvent comprises at least one of ester solvent, ether solvent, alcohol solvent, and alcohol ester solvent.

8. A low temperature cure paste for thick film hybrid circuits according to claim 1 wherein, The cross-linking curing agent comprises at least one of diamino diphenyl sulfone, diamino diphenyl methane, m-phenylenediamine, isophorone diamine, and N-aminoethyl piperazine.

9. A low temperature cure paste for thick film hybrid circuits according to claim 1 wherein, The functional aid comprises at least one of dispersant, defoaming agent, and leveling agent.

10. A process for the preparation of a low temperature cure paste for thick film hybrid circuits according to any one of claims 1 to 9, characterized in that The method comprises the following steps: S1: dissolving the thermosetting resin in the solvent, stirring and mixing to obtain the organic carrier; S2: stirring and mixing the organic carrier, solid filler, cross-linking curing agent, and functional aid to obtain the preliminary slurry; S3: grinding and dispersing the preliminary slurry, filtering, and defoaming to obtain the low-temperature curing slurry for thick film hybrid circuit.

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