Rapid forming method of integrated low-temperature co-fired ceramic substrate of integrated air bridge

Abstract

The invention provides a rapid forming method of an integrated low-temperature co-fired ceramic substrate integrated with an air bridge, and relates to the technical field of hybrid integrated circuits. The rapid prototyping method specifically comprises the following steps: preparing an LTCC green body; preparing an organic solvent; preparing isolation layer precursor slurry; preparing supporting layer slurry; air bridge printing; and sintering and molding an air bridge. According to the invention, the air bridge structure is prepared by adopting a printing process, and then the air bridge structure is formed while the integrated LTCC substrate is prepared in combination with a low-temperature ceramic co-firing process path, the integrated air bridge process and the LTCC process are completely compatible and synchronously sintered and molded, the processing time is saved, additional special equipment is not needed, and the production cost can be greatly reduced. Compared with an air bridge structure prepared by a traditional photoetching process, the air bridge structure prepared by the method has higher high temperature resistance and smaller parasitic capacitance (the microwave performance is more excellent), so that the requirements of more application environments can be met, and higher reliability is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of hybrid integrated circuits, and in particular to a rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge. Background Art

[0002] Low-temperature co-fired ceramic (LTCC) technology offers the advantages of high-density wiring and passive integration, enabling large-scale integration and high-density packaging of passive components. Rapidly increasing characteristic frequencies and increasing power levels, particularly for high-power microwave devices, place higher demands on interconnects. Therefore, it is necessary to develop an interconnect technology with low parasitic capacitance, low resistance, and simple processing.

[0003] Air bridges, as an interconnect technology, have been widely used in various active and passive devices. Using air, which has the lowest dielectric constant, as a dielectric, air bridges minimize parasitic capacitance and inductance per unit area at interconnect intersections, improving device frequency characteristics while also reducing device area, increasing integration density, and saving manufacturing costs. Furthermore, in designs with complex microstrip wiring, such as delay circuits and power dividers, air bridge structures are also necessary to further enhance integration and microwave performance while reducing parasitic effects caused by cross-connections.

[0004] Traditional methods for preparing air bridges, such as the solutions disclosed in application numbers 202311684530.8 and 202310731446.0, have the same point that they both require first setting a photoresist on a substrate, and then setting a bridge pier on the photoresist. The photoresist layer serves as a reserved air layer and is removed in the subsequent preparation process through a photolithography process, namely exposure, development, etching, and stripping, thereby forming an air bridge.

[0005] LTCC substrates are typically manufactured through thick-film printing and sintering. On the one hand, the raw and most processed porcelain of LTCC substrates cannot withstand the damage caused by acidic and alkaline solutions during the development and etching processes, which can cause penetrating corrosion and significantly reduce the strength. On the other hand, the printed circuit patterns on the surface of LTCC substrates are prone to sputtering contamination from developer solutions, corrosion, and peeling, resulting in reduced adhesion between the center conductor metal layer and the ground metal layer on the substrate surface, and reduced reliability. Therefore, traditional air bridge preparation methods cannot be applied to LTCC substrates, and there are currently no reports on the integration of air bridges on LTCC substrates.

[0006] In summary, the present invention provides a rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge. This method is compatible with the LTCC substrate processing technology, does not affect the LTCC substrate ceramic body and surface circuit patterns, and ensures stable improvement of the relevant performance of the LTCC substrate. Summary of the Invention

[0007] (1) Technical problems solved

[0008] In response to the shortcomings of the existing technology, the present invention provides a rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge, which solves the technical problem that the traditional air bridge preparation method cannot integrate the air bridge on the LTCC substrate, and also solves the technical problem that the traditional air bridge has limited height and large parasitic capacitance.

[0009] (2) Technical solution

[0010] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0011] A rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge includes the following steps:

[0012] Step 1-1: LTCC green body preparation

[0013] Prepare an LTCC green body containing interlayer interconnection through holes and circuit patterns, print positioning marks, a center conductive strip and a ground metal layer on the surface of the LTCC green body, with the ground metal layer located on both sides of the center conductive strip, and prepare an LTCC green body substrate with a coplanar waveguide for use;

[0014] Step 2-1: Preparation of organic solvent

[0015] Mix terpineol, ethanol, butyl phthalate, ethyl cellulose and triolein to prepare an organic solvent for later use;

[0016] Step 3-1: Preparation of isolation layer precursor slurry

[0017] The coke powder and carbon black powder are stirred and mixed evenly, and then ground to obtain a mixed powder, which is used as the functional solid phase of the isolation layer;

[0018] Take the above organic solvent, add the isolation layer functional solid phase into the organic solvent, mix and stir evenly, and then perform ball milling and vacuum degassing to prepare the isolation layer precursor slurry for use;

[0019] Step 4-1: Air Bridge Printing

[0020] When the air bridge height is ≤15μm:

[0021] Separately preparing an isolation layer screen printing plate and a metal layer screen printing plate;

[0022] Printing the isolation layer: Use the positioning mark for alignment, use the isolation layer screen to print the isolation layer slurry across the center guide belt and overlap the ground metal layer. After printing, let it stand for 15 to 30 minutes to dry to obtain the isolation layer. The isolation layer can be printed repeatedly to increase the overall height of the air bridge;

[0023] Printed flyover: Use a metal layer screen printing plate to print flyovers on the isolation layer to form an air bridge structure;

[0024] Step 5-1: Air bridge sintering

[0025] The printed LTCC green body is placed on a firing plate with the side with the air bridge structure facing upwards, and is placed in a muffle furnace for sintering. After the furnace body cools naturally, the sintered integrated LTCC ceramic is taken out, and the residues of the isolation layer on the surface of the substrate after sintering are removed to obtain an integrated LTCC substrate with an integrated air bridge structure.

[0026] A rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge includes the following steps:

[0027] When the air bridge height is greater than 15 μm, first perform steps 1-1, 2-1, and 3-1 as described in claim 1, and then perform the following steps:

[0028] Step 4-2: Preparation of support layer slurry

[0029] Alumina powder, zirconium oxide powder, calcium oxide and borosilicate glass powder are mixed and stirred evenly, and the mixed powder obtained by grinding is used as the functional solid phase of the support layer;

[0030] Take the above organic solvent, add the functional solid phase of the support layer into it, mix and stir evenly, and then perform ball milling and vacuum degassing to prepare the support layer precursor slurry for use;

[0031] Step 5-2: Air Bridge Printing

[0032] Separately preparing an isolation layer screen printing plate, a support layer screen printing plate, and a metal layer screen printing plate;

[0033] Printing the isolation layer: Use the positioning mark for alignment, use the isolation layer screen to print the isolation layer slurry across the center guide belt and overlap the ground metal layer. After printing, let it stand for 15 to 30 minutes to dry to obtain the isolation layer. The isolation layer can be printed repeatedly to increase the overall height of the air bridge;

[0034] Printing the support layer: using positioning marks for alignment, using a support layer stencil to print the support layer slurry on the isolation layer, with the width of the support layer shrinking by 100 to 200 μm compared to the isolation layer; the overlap length of the support layer and the grounding metal layers on both sides exceeds the isolation layer by 100 to 200 μm; after printing, let it stand for 15 to 30 minutes to dry, thereby obtaining the support layer;

[0035] Printed flyover: Print the flyover on the support layer. The width of the flyover should not be greater than the width of the support layer. The overlap length between the flyover and the grounding metal layers on both sides should exceed the support layer by 100-200μm to form an air bridge structure.

[0036] Step 6-2: Air bridge sintering

[0037] The printed LTCC green body is placed on a firing plate with the side with the air bridge structure facing upwards, and is placed in a muffle furnace for sintering. After the furnace body cools naturally, the sintered integrated LTCC ceramic is taken out, and the residues of the isolation layer on the surface of the substrate after sintering are removed to obtain an integrated LTCC substrate with an integrated air bridge structure.

[0038] Preferably, the printing paste used for the central conductive strip, the ground metal layer and the overpass can be any one of gold paste, silver paste and copper paste.

[0039] Preferably, the proportions of the components in the organic solvent are as follows: 60-80% by mass of terpineol, 2-5% by mass of ethanol, 10-20% by mass of butyl phthalate, 5-10% by mass of ethyl cellulose, and 2-5% by mass of triolein.

[0040] Preferably, the isolation layer functional solid phase accounts for 60-75% of the isolation layer slurry.

[0041] Preferably, the proportion of the support layer functional solid phase in the support layer precursor slurry is 70-90%.

[0042] Preferably, in the functional solid phase of the support layer, the mass fraction of aluminum oxide powder is 30-40%, the mass fraction of zirconium oxide powder is 5%-10%, the mass fraction of calcium oxide is 5%-10%, and the mass fraction of borosilicate glass powder is 50-60%.

[0043] Preferably, the drying conditions after printing the isolation layer, support layer or overpass are: oven temperature 65-80° C., drying time 30-60 min.

[0044] Preferably, the thickness of the screen-printed photoresist on the isolation layer is 10-50 μm; the thickness of the screen-printed photoresist on the support layer is 10-50 μm; and the thickness of the screen-printed photoresist on the overpass is 10-35 μm.

[0045] Preferably, the sintering conditions of the integrated LTCC substrate are: keeping at 230-310° C. for 1-2 hours, heating to 460-500° C. for 2-4 hours; then heating to 855-875° C. for 15-20 minutes.

[0046] At temperatures between 230°C and 460°C and 500°C, the LTCC substrate undergoes debinding. After debinding and foaming, the substrate body becomes loose, with most of its particles separated and the interparticle gaps increasing. As the sintering temperature rises to 855°C to 875°C, the ceramic powder begins to absorb heat and soften, with the ceramic particles constantly contacting and rearranging, gradually eliminating large pores and forming closed pores. During the sintering stage at 855°C to 875°C, the coke and carbon black in the isolation layer are partially burned to ash, making the internal structure loose and easy to separate. The sintered material in the isolation layer is then removed to form an air bridge.

[0047] (3) Beneficial effects

[0048] The present invention provides a rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge. Compared with the existing technology, it has the following advantages:

[0049] 1. The present invention adopts a printing process to prepare an air bridge structure and then combines it with a low-temperature ceramic co-firing process to form the air bridge structure while preparing an integrated LTCC substrate. The integrated air bridge process is fully compatible with the LTCC process and can be sintered and formed simultaneously, saving processing time and not requiring additional special equipment, which can significantly reduce production costs.

[0050] 2. The air bridge structure prepared by the present invention is taller than the air bridge prepared by the traditional method, especially the air bridge with a supporting layer structure, whose height can reach hundreds of microns. Therefore, the parasitic capacitance it generates is smaller and the microwave performance is also better.

[0051] 3. The air bridge structure prepared by the present invention can withstand high temperatures of over 600°C, which is much higher than the high temperature resistance of the air bridge structure prepared by the existing photolithography process.

[0052] 4. The air bridge structure prepared by the present invention has higher high temperature resistance and smaller parasitic capacitance (better microwave performance) than the air bridge structure prepared by the traditional photolithography process. Therefore, it can meet the needs of more application environments and has higher reliability.

[0053] 5. The present invention integrates an air bridge structure on an LTCC substrate for the first time. The key dimensions of the obtained air bridge structure, such as height, bandwidth, and spacing, can be customized according to product design requirements without being restricted by raw materials, processes, or equipment, and the operation is flexible and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0055] Figure 1 Schematic diagram of the structure of the LTCC green body with coplanar waveguide according to Example 1 or Example 2 of the present invention, wherein Figure a is a top view and Figure b is a cross-sectional view;

[0056] Figure 2 This is a schematic diagram of Example 1 or Example 2 of the present invention after printing the isolation layer;

[0057] Figure 3 This is a schematic diagram of a printed overpass (without a supporting layer) according to Example 1 of the present invention;

[0058] Figure 4 This is a schematic diagram of the air bridge without a supporting layer after sintering according to Example 1 of the present invention;

[0059] Figure 5 This is a schematic diagram of Example 2 of the present invention after printing the support layer;

[0060] Figure 6 This is a schematic diagram of a printed overpass (with a support layer) according to Example 2 of the present invention;

[0061] Figure 7 This is a schematic diagram of the air bridge with a support layer after sintering in Example 2 of the present invention.

[0062] Among them, 1. Center conduction tape; 2. Grounding metal layer; 3. LTCC green substrate; 4. Isolation layer; 5. Support layer; 6. Flyover; 7. Air medium; 8. Center conduction tape after sintering; 9. Grounding metal layer after sintering; 10. LTCC substrate after sintering; 11. Flyover after sintering; 12. Support layer after sintering. DETAILED DESCRIPTION

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0064] The embodiments of the present invention provide a method for rapid prototyping of an integrated low-temperature co-fired ceramic substrate with an integrated air bridge, resolving the technical issues of conventional air bridge fabrication methods, which prevent the integration of air bridges on LTCC substrates, as well as the limited height and high parasitic capacitance of conventional air bridges. This invention integrates an air bridge structure on an LTCC substrate for the first time. Compared to air bridge structures fabricated using conventional photolithography processes, the resulting air bridge structure exhibits higher temperature resistance, lower parasitic capacitance, and superior microwave performance. Therefore, it can meet the needs of a wider range of application environments and offers higher reliability.

[0065] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0066] Example 1:

[0067] like Figure 1 As shown, the rapid prototyping method of an integrated low-temperature co-fired ceramic substrate with an integrated air bridge includes the following specific steps:

[0068] Step 1: Substrate preparation

[0069] A 15-layer LTCC green substrate 3 containing interlayer interconnected through-holes and circuit patterns is prepared through conventional punching, filling, printing, lamination, and static pressing processes. Circular positioning marks, a center conductive strip 1, and a grounding metal layer 2 are printed on the surface of the LTCC green substrate 3. The grounding metal layer 2 is located on both sides of the center conductive strip 1 and is not connected to the center conductive strip 1. The printing paste for the circular positioning marks, the center conductive strip 1, and the grounding metal layer 2 is all gold paste.

[0070] The width of the central conductive strip 1 is 0.29 mm. The distance between the central conductive strip 1 and the grounding metal layers 2 on both sides is 0.25 mm. The thickness of the grounding metal layers 2 is 10 μm. The prepared LTCC green substrate 3 with coplanar waveguide is ready for use.

[0071] Step 2: Organic solvent preparation

[0072] Weigh 280g of terpineol and 20g of ethanol, stir and mix, then add 20g of ethyl cellulose and continue stirring until completely dissolved. Then weigh 60g of butyl phthalate and 20g of triolein and add them to the mixed solution and continue stirring to prepare an organic solvent for later use.

[0073] Step 3: Preparation of isolation layer slurry

[0074] Mix 48g of coke powder and 72g of carbon black powder evenly and grind them in a mortar for 15-30min. The obtained mixed powder is used as the functional solid phase of the isolation layer 4.

[0075] 80 g of the organic solvent prepared above was ball-milled together with the functional solid phase of the isolation layer 4 in a ball mill for 6 hours, and then vacuum-defoamed to obtain a precursor slurry of the isolation layer 4.

[0076] Step 4: Air Bridge Printing

[0077] The required air bridge height is ≤15μm. The isolation layer screen printing and the metal layer screen printing are prepared with a screen mesh of 325, a wire diameter of 23μm, a screen tension of 30N, a photosensitive resin thickness of 18μm, a printing screen distance of 1.5mm, and a printing speed of 100mm / s.

[0078] Printing the isolation layer: Use the positioning mark for alignment, and use the isolation layer stencil to print the isolation layer 4 slurry on the center guide 1; the printing width of the isolation layer 4 is 0.6mm; the overlap length between the isolation layer 4 and the grounding metal layer 2 on both sides is 100μm; after printing, let it stand for 30 minutes, and then put it into a 70℃ oven to dry for 30 minutes.

[0079] Printing the flyover: Select gold paste and use a metal layer screen printing plate to print another layer of metal conductive tape on the isolation layer 4 as the flyover 6. The printed metal conductive tape has a width of 0.29 mm and is then placed in a 70°C oven for 30 minutes to form an air bridge structure.

[0080] Step 5: Air bridge sintering

[0081] The integrated LTCC green substrate 3 printed with the air bridge structure is placed on a quartz support plate with the air bridge structure facing upward and placed in a muffle furnace for firing. The LTCC green substrate 3 is kept at 250°C for 2 hours, then heated to 460°C and kept for 2 hours. The temperature is then raised to 855°C and kept for 15 minutes. After the furnace body is naturally cooled, the sintered integrated LTCC porcelain is taken out and the residue of the sintered isolation layer 4 on the surface of the substrate is removed to obtain an integrated LTCC substrate with an integrated air bridge structure.

[0082] Example 2:

[0083] like Figure 2 As shown, the rapid prototyping method of an integrated low-temperature co-fired ceramic substrate with an integrated air bridge includes the following specific steps:

[0084] Step 1: Substrate preparation

[0085] A 20-layer LTCC green body 3 containing interlayer interconnecting through-holes and circuit patterns was prepared through conventional punching, filling, printing, lamination, and static pressing processes. A circular positioning mark, a center conductive strip 1, and a grounding metal layer 2 were printed on the surface of the LTCC green body 3. The grounding metal layer 2 was located on both sides of the center conductive strip 1 and was not connected to the center conductive strip 1. The printing paste for the circular positioning mark, the center conductive strip 1, and the grounding metal layer 2 was all gold paste.

[0086] The width of the central conductive strip 1 is 0.22 mm. The distance between the central conductive strip 1 and the grounding metal layers 2 on both sides is 0.25 mm. The thickness of the grounding metal layers 2 is 12 μm. The prepared LTCC green body 3 with coplanar waveguide is ready for use.

[0087] Step 2: Organic solvent preparation

[0088] Weigh 320g of terpineol and 8g of ethanol, stir well, then add 24g of ethyl cellulose and continue stirring until completely dissolved. Then weigh 40g of butyl phthalate and 8g of triolein and add them to the mixed solution and continue stirring to prepare an organic solvent for later use.

[0089] Step 3: Preparation of isolation layer slurry

[0090] 70g of coke powder and 70g of carbon black powder were mixed evenly and ground in a mortar for 20min. The obtained mixed powder was used as the functional solid phase of the isolation layer 4;

[0091] 60 g of the organic solvent prepared above was ball-milled together with the functional solid phase of the isolation layer 4 in a ball mill for 6 hours, and vacuum degassing was performed to obtain a precursor slurry of the isolation layer 4.

[0092] Step 4: Preparation of support layer slurry

[0093] 42g of aluminum oxide powder, 7g of zirconium oxide powder, 7g of calcium oxide and 84g of borosilicate glass powder were mixed evenly and ground in a mortar for 30min. The obtained mixed powder was used as the functional solid phase of the support layer 5;

[0094] 60 g of the organic solvent and the functional solid phase of the support layer 5 were ball-milled in a ball mill for 12 hours, and then vacuum-defoamed to obtain a precursor slurry of the support layer 5.

[0095] Step 5: Air Bridge Printing

[0096] The required air bridge height is greater than 15 μm. The isolation layer screen printing, support layer screen printing and metal layer screen printing are prepared. The screen mesh number is 400, the screen tension is 27N, the photosensitive resin thickness is 25 μm, the printing screen distance is 2mm, and the printing speed is 80 mm / s.

[0097] Printing the isolation layer: Use the positioning mark for alignment, and use the isolation layer stencil to print the isolation layer 4 slurry on the center guide 1; the printing width of the isolation layer 4 is 0.5mm; the overlap length between the isolation layer 4 and the grounding metal layer 2 on both sides is 150μm; after printing, let it stand for 30 minutes, and then put it into a 75℃ oven to dry for 60 minutes.

[0098] Printing support layer: Use positioning marks for alignment, and use a support layer stencil to print support layer 5 slurry on the isolation layer 4. The width of support layer 5 is 200μm smaller than that of isolation layer 4. The overlap length of support layer 5 and grounding metal layers 2 on both sides exceeds 4200μm of isolation layer. After printing, let it stand for 30 minutes to dry, and then put it into a 75℃ oven for 60 minutes to dry to obtain support layer 5.

[0099] Printing the flyover: Select gold paste and use a metal layer screen printing plate to print another layer of metal conductive tape on the isolation layer 4 as the flyover 6. The printed metal conductive tape has a width of 0.22 mm and is then placed in a 75°C oven for 60 minutes to form an air bridge structure.

[0100] Step 6: Air bridge sintering

[0101] The integrated LTCC green substrate 3 printed with the air bridge structure is placed on a quartz support plate with the air bridge structure facing upward and placed in a muffle furnace for firing. The LTCC green substrate 3 is kept at 230°C for 3 hours, then heated to 480°C and kept for 3 hours. The temperature is then raised to 875°C and kept for 16 minutes. After the furnace body is naturally cooled, the sintered integrated LTCC porcelain is taken out and the residue of the sintered isolation layer 4 on the surface of the substrate is removed to obtain an integrated LTCC substrate with an integrated air bridge structure.

[0102] In summary, compared with the existing technology, the present invention has the following beneficial effects:

[0103] 1. The present invention adopts a printing process to prepare an air bridge structure and then combines it with a low-temperature ceramic co-firing process to form an air bridge structure while preparing an integrated LTCC substrate. The integrated air bridge process is fully compatible with the LTCC process and can be sintered and formed simultaneously, saving processing time and not requiring additional special equipment, which can significantly reduce production costs.

[0104] 2. The air bridge structure prepared by the present invention is taller than the air bridge prepared by the traditional method, especially the air bridge with a supporting layer structure, whose height can reach hundreds of microns. Therefore, the parasitic capacitance it generates is smaller and the microwave performance is also better.

[0105] 3. The air bridge structure prepared by the present invention can withstand high temperatures of over 600°C, which is much higher than the high temperature resistance of the air bridge structure prepared by the existing photolithography process.

[0106] 4. The air bridge structure prepared by the present invention has higher high temperature resistance and smaller parasitic capacitance (better microwave performance) than the air bridge structure prepared by the traditional photolithography process. Therefore, it can meet the needs of more application environments and has higher reliability.

[0107] 5. The present invention integrates an air bridge structure on an LTCC substrate for the first time. The key dimensions of the obtained air bridge structure, such as height, bandwidth, and spacing, can be customized according to product design requirements without being restricted by raw materials, processes, or equipment, and the operation is flexible and convenient.

[0108] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0109] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge, characterized in that: The specific steps include: Step 1-1: LTCC green body preparation Prepare an LTCC green body containing interlayer interconnection through holes and circuit patterns, print positioning marks, a center conductive strip and a ground metal layer on the surface of the LTCC green body, with the ground metal layer located on both sides of the center conductive strip, and prepare an LTCC green body substrate with a coplanar waveguide for use; Step 2-1: Preparation of organic solvent Mix terpineol, ethanol, butyl phthalate, ethyl cellulose and triolein to prepare an organic solvent for later use; Step 3-1: Preparation of isolation layer precursor slurry The coke powder and carbon black powder are stirred and mixed evenly, and then ground to obtain a mixed powder, which is used as the functional solid phase of the isolation layer; Take the above organic solvent, add the isolation layer functional solid phase into the organic solvent, mix and stir evenly, and then perform ball milling and vacuum degassing to prepare the isolation layer precursor slurry for use; Step 4-1: Air Bridge Printing When the air bridge height is ≤15μm, prepare the isolation layer screen printing and the metal layer screen printing respectively; Printing the isolation layer: Use the positioning mark for alignment, use the isolation layer screen to print the isolation layer slurry across the center guide belt and overlap the ground metal layer. After printing, let it stand for 15 to 30 minutes to dry to obtain the isolation layer. The isolation layer can be printed repeatedly to increase the overall height of the air bridge; Printed flyover: Use a metal layer screen printing plate to print flyovers on the isolation layer to form an air bridge structure; Step 5-1: Air bridge sintering molding The printed LTCC green body is placed on a firing plate with the side with the air bridge structure facing upwards, and is placed in a muffle furnace for sintering. After the furnace body cools naturally, the sintered integrated LTCC ceramic is taken out, and the residues of the isolation layer on the surface of the substrate after sintering are removed to obtain an integrated LTCC substrate with an integrated air bridge structure.

2. A rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge, characterized in that: The specific steps include: When the air bridge height is greater than 15 μm: First perform steps 1-1, 2-1, and 3-1 as described in claim 1, and then perform the following steps: Step 4-2: Preparation of support layer slurry Alumina powder, zirconium oxide powder, calcium oxide and borosilicate glass powder are mixed and stirred evenly, and the mixed powder obtained by grinding is used as the functional solid phase of the support layer; Take the above organic solvent, add the functional solid phase of the support layer into it, mix and stir evenly, and then perform ball milling and vacuum degassing to prepare the support layer precursor slurry for use; Step 5-2: Air Bridge Printing Separately preparing an isolation layer screen printing plate, a support layer screen printing plate, and a metal layer screen printing plate; Printing the isolation layer: Use the positioning mark for alignment, use the isolation layer screen to print the isolation layer slurry across the center guide belt and overlap the ground metal layer. After printing, let it stand for 15 to 30 minutes to dry to obtain the isolation layer. The isolation layer can be printed repeatedly to increase the overall height of the air bridge; Printing the support layer: using positioning marks for alignment, using a support layer stencil to print the support layer slurry on the isolation layer, with the width of the support layer shrinking by 100 to 200 μm compared to the isolation layer; the overlap length of the support layer and the grounding metal layers on both sides exceeds the isolation layer by 100 to 200 μm; after printing, let it stand for 15 to 30 minutes to dry, thereby obtaining the support layer; Printed flyover: Print the flyover on the support layer. The width of the flyover should not be greater than the width of the support layer. The overlap length between the flyover and the grounding metal layers on both sides should exceed the support layer by 100-200μm to form an air bridge structure. Step 6-2: Air bridge sintering The printed LTCC green body is placed on a firing plate with the side with the air bridge structure facing upwards, and is placed in a muffle furnace for sintering. After the furnace body cools naturally, the sintered integrated LTCC ceramic is taken out, and the residues of the isolation layer on the surface of the substrate after sintering are removed to obtain an integrated LTCC substrate with an integrated air bridge structure.

3. The rapid prototyping method of an integrated low-temperature co-fired ceramic substrate with integrated air bridge according to claim 1 or 2, characterized in that: The printing paste used for the central conductive strip, the ground metal layer, and the overpass may be any one of gold paste, silver paste, and copper paste.

4. The rapid prototyping method of an integrated low-temperature co-fired ceramic substrate with integrated air bridge according to claim 1 or 2, characterized in that: The proportions of the components in the organic solvent are as follows: 60-80% by mass of terpineol, 2-5% by mass of ethanol, 10-20% by mass of butyl phthalate, 5-10% by mass of ethyl cellulose, and 2-5% by mass of triolein.

5. The rapid prototyping method of an integrated low-temperature co-fired ceramic substrate with integrated air bridge according to claim 1 or 2, characterized in that: The isolation layer functional solid phase accounts for 60-75% of the isolation layer slurry.

6. The rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge according to claim 2, characterized in that: The proportion of the support layer functional solid phase in the support layer precursor slurry is 70-90%.

7. The rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge according to claim 2, characterized in that: In the functional solid phase of the support layer, the mass fraction of aluminum oxide powder is 30-40%, the mass fraction of zirconium oxide powder is 5-10%, the mass fraction of calcium oxide is 5-10%, and the mass fraction of borosilicate glass powder is 50-60%.

8. The rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge according to claim 1 or 2, characterized in that: The drying conditions after printing the isolation layer, support layer or overpass are: oven temperature 65-80°C, drying time 30-60 minutes.

9. The rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge according to claim 1 or 2, characterized in that: The thickness of the screen-printed photoresist on the isolation layer is 10 to 50 μm; the thickness of the screen-printed photoresist on the support layer is 10 to 50 μm; the thickness of the screen-printed photoresist on the overpass is 10 to 35 μm.

10. The rapid prototyping method for an integrated low-temperature co-fired ceramic substrate with an integrated air bridge according to claim 1 or 2, characterized in that: The sintering conditions of the integrated LTCC substrate are: keeping the temperature at 230-310° C. for 1-2 hours, heating to 460-500° C. for 2-4 hours, and then heating to 855-875° C. for 15-20 minutes.

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