A multilayer glass substrate and a method of making the same

Abstract

This invention discloses a multilayer glass substrate and its preparation method, relating to the field of glass substrate technology. The method first provides a pre-formed glass substrate, forming through-holes penetrating its thickness direction. Then, conductive paste is filled into the through-holes, and the filled glass substrate undergoes a desizing process to remove organic matter from the conductive paste. Finally, at least two desizing glass substrates are stacked along their thickness direction to form a composite. This invention eliminates multiple steps in traditional processes such as sputtering, photolithography, electroplating, and temporary bonding, significantly reducing the overall process steps. It eliminates the need for high-value consumables such as electroplating solutions, sputtering targets, and polishing pads, significantly reducing the material cost of substrate preparation. The paste printing vacuum adsorption filling scheme is not limited by liquid exchange within the holes, can adapt to ultra-high aspect ratio through-hole structures, has fewer filling defects inside the through-holes, and does not rely on electroplating filling processes to achieve vertical conductive channel formation.

Description

Technical Field

[0001] This invention relates to the field of glass substrate technology, specifically to a multilayer glass substrate and its preparation method. Background Technology

[0002] For a long time, glass substrates have gradually replaced silicon substrates and organic substrates in multi-chip packaging due to their advantages of low loss and low cost. With the development of 2.5D and 3D advanced packaging, glass through-hole (TGV) and redistribution layer (RDL) have become the core technologies for their large-scale application and are widely applicable to high-density interconnection scenarios such as Mini / Micro-LED, biomedicine, and consumer electronics.

[0003] The existing TGV fabrication process involves laser-induced local modification of the glass followed by wet etching to form through-holes, and then multiple processes such as metal sputtering, photolithography, electroplating, and chemical mechanical polishing to complete the metallization of the through-holes and the surface RDL wiring. This process is complex, electroplating limits the aspect ratio of the through-holes, the bonding strength between the metal layer and the glass substrate is insufficient, the substrate is prone to stress accumulation and warping, and it is difficult to embed passive devices inside the glass. Overall, the fabrication cost and integration capability have significant shortcomings. Summary of the Invention

[0004] The purpose of this invention is to provide a multilayer glass substrate and its preparation method to solve the problems in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A multilayer glass substrate and its preparation method, comprising the following steps: Step 1: Provide a pre-formed glass substrate and form a through hole in the glass substrate that extends through its thickness direction; Step 2: Fill the through holes with conductive paste and perform a desmearing process on the glass substrate after filling to remove organic matter from the conductive paste; Step 3: Stack at least two glass substrates, after the adhesive removal process, along the thickness direction to form a stacked body; Step 4: The superimposed body is co-fired at a temperature above the softening point of the glass substrate, so that the interfaces of adjacent glass substrates are fused together, and the conductive paste in the through hole forms interlayer vertical interconnection channels after sintering, thus forming a multilayer co-fired glass substrate.

[0006] Based on the above technical solutions, the present invention also provides the following optional technical solutions: In one alternative: after forming the through hole, the step of forming a blind groove on at least one surface of the glass substrate is further included; the conductive paste is simultaneously filled into the through hole and the blind groove.

[0007] In one alternative, the through-hole is formed by: modifying a local area of ​​the glass substrate with a laser, and then selectively removing the glass material in the modified area with an etching solution. The etching solution is a hydrofluoric acid etching solution.

[0008] In one alternative: the conductive paste is a copper-based electronic paste or a silver-based electronic paste; the conductive paste is filled by a combination of printing and vacuum adsorption processes.

[0009] In one alternative: both the debinding process and the co-firing are performed in a protective atmosphere; the co-firing temperature is above the softening point of the glass substrate and below the full flow temperature of the glass substrate.

[0010] In one alternative: when the glass substrates are stacked, a positioning structure is provided between each layer of the glass substrates to ensure that the through holes on different layers of the glass substrates are aligned in the thickness direction; the circuit patterns on each layer of the glass substrates may be the same or different.

[0011] In one alternative: the cross-sectional shape of the blind slot is any one of rectangle, semicircle or trapezoid; the conductive paste filled in the blind slot is any one of resistive paste, capacitive paste or inductive paste, so as to realize the in-layer integration of embedded passive devices.

[0012] In one alternative approach, the following steps are also included: Step 5: Flatten the surface of the multilayer co-fired glass substrate and finally cut off the edges.

[0013] A multilayer glass substrate, manufactured using the above-described method for preparing a multilayer glass substrate, comprises at least two pre-formed glass substrates. The interface between two adjacent glass substrates is a glass-glass fusion bonding interface formed by co-firing. Each glass substrate has a through-hole extending through its thickness direction. A sintered conductor is disposed within the through-hole. Vertical electrical interconnection is achieved between different glass substrates through the sintered conductor.

[0014] At least one surface of the glass substrate is provided with a blind groove, and the blind groove is filled with a sintered conductive body or a functional paste sintered body, wherein the functional paste sintered body is any one of a resistor, a capacitor or an inductor.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention eliminates multiple processes such as sputtering, photolithography, electroplating, and temporary bonding in traditional processes, significantly reducing the overall process steps. It eliminates the need for high-value consumables such as electroplating solutions, sputtering targets, and polishing pads, resulting in a significant reduction in substrate preparation material costs. The paste printing vacuum adsorption filling scheme is not limited by liquid exchange within the holes, can be adapted to ultra-high aspect ratio through-hole structures, has fewer filling defects inside the through-holes, and does not rely on electroplating filling processes to achieve vertical conductive channel formation.

[0016] 2. In this invention, the substrate is co-fired in the glass softening zone and is in a semi-molten state. The inorganic phase of the conductive paste forms a microscopic interlocking interface with the glass matrix. The bonding strength between the conductor and the glass is higher than that of the traditional sputtering and electroplating physical adhesion structure. It is less prone to delamination and cracking under thermal cycling conditions. The co-firing simultaneously completes the melting and bonding of multiple layers of glass and the interlayer conductive interconnection, eliminating the need for additional interlayer conduction processes. The multilayer substrate is integrally formed, resulting in lower overall warpage stress and better flatness than traditional multi-film process substrates.

[0017] 3. This invention can process blind slots on the substrate and fill them with different functional pastes. After co-firing, passive devices can be directly integrated inside the substrate, and vertical through-hole interconnects and planar wiring networks can be constructed simultaneously without the need for additional passive device mounting processes. The circuit patterns of each substrate layer can be designed independently and differentiated, and matched with corresponding conductive or functional pastes, resulting in greater design freedom for multi-layer circuit layout and functional integration. Attached Figure Description

[0018] Figure 1 This is a simplified diagram of a conventional TGV process.

[0019] Figure 2 This is a flowchart of the glass substrate hole metallization and embedded circuit process of the present invention.

[0020] Figure 3 This is a schematic diagram of the process flow for the multilayer co-fired glass substrate (MLCG) of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0022] In one embodiment, such as Figures 1-3 As shown, a multilayer glass substrate and its preparation method include the following steps: Step 1: Provide a pre-formed glass substrate and form a through hole in the glass substrate that extends through its thickness direction; Step 2: Fill the through holes with conductive paste and perform a desmearing process on the glass substrate after filling to remove organic matter from the conductive paste; Step 3: Stack at least two glass substrates, after the adhesive removal process, along the thickness direction to form a stacked body; Step 4: The superimposed body is co-fired at a temperature above the softening point of the glass substrate, so that the interfaces of adjacent glass substrates are fused together, and the conductive paste in the through hole forms interlayer vertical interconnection channels after sintering, thus forming a multilayer co-fired glass substrate.

[0023] In this embodiment, the core of the above method lies in using a pre-formed rigid glass substrate as raw material. After filling the through-holes with conductive paste and removing organic matter through debinding, multiple glass substrates are stacked and co-fired above the glass softening point. During co-firing, the glass substrate is in a semi-softened state, and the interfaces between adjacent layers melt and bond under the influence of temperature and pressure, forming a monolithic glass block structure. Simultaneously, the inorganic phase in the conductive paste within the through-holes shrinks and densifies during sintering, forming a continuous sintered conductor that penetrates the thickness direction of each glass substrate layer, thereby establishing a vertical electrical interconnection channel between adjacent layers. Because the co-firing temperature is controlled above the glass softening point but below the full flow temperature, the glass substrate achieves interlayer bonding while maintaining a certain shape stability. This avoids substrate warping and circuit misalignment caused by excessive deformation and ensures the interlayer bonding strength. This method significantly reduces the number of steps, eliminating the need for complex processes such as sputtering, photolithography, and electroplating, as well as chemical mechanical polishing to remove the surface metal layer. It achieves interlayer mechanical bonding and electrical interconnection simultaneously through filling and co-firing, thereby reducing manufacturing costs and process complexity.

[0024] In one alternative: after forming the through hole, the step of forming a blind groove on at least one surface of the glass substrate is further included; the conductive paste is simultaneously filled into the through hole and the blind groove.

[0025] The blind trench can be processed at a specified location on the surface of the glass substrate using a laser cutting machine. Its cross-sectional shape can be rectangular, semi-circular, or trapezoidal, depending on the wiring requirements. The introduction of the blind trench allows conductive paste to be simultaneously filled into both the vias and the blind trench during the filling process. After desizing and co-firing, the sintered conductors within the blind trench form planar conductive lines on the glass substrate surface, while the sintered conductors within the vias achieve vertical interconnection between layers, thus forming a complete three-dimensional electrical network. Compared to solutions that only form vertical interconnections within vias, the blind trench solution further integrates surface wiring and intra-layer interconnection.

[0026] In one embodiment, the through-hole is formed by: modifying a local area of ​​the glass substrate with a laser, and then selectively removing the glass material in the modified area with an etching solution; The etching solution is a hydrofluoric acid etching solution.

[0027] The laser can be a picosecond or femtosecond pulsed laser. By focusing it inside or on the surface of the glass substrate, it relaxes the glass mesh structure in the modified area and forms microcracks, thereby achieving a higher etching rate in subsequent etching processes. The etching solution is hydrofluoric acid, utilizing the difference in etching rates between the modified and unmodified areas in hydrofluoric acid to quickly remove the glass material in the modified area, forming through-holes. For thinner glass substrates, single-sided laser irradiation combined with single-sided etching can be used to create through-holes; for thicker glass substrates, double-sided laser irradiation is used, causing the modified area to extend from both sides of the substrate towards each other, resulting in nearly vertical hole walls and mitigating the issue of the hole being thin in the middle and thick at both ends.

[0028] In one embodiment, the conductive paste is a copper-based electronic paste or a silver-based electronic paste; the conductive paste is filled by a combination of printing and vacuum adsorption processes.

[0029] The filling method combines printing and vacuum adsorption processes. Specifically, conductive paste is printed onto the surface of a glass substrate, covering the through-hole openings. Simultaneously, a low vacuum is applied to the back of the substrate, causing the conductive paste to be drawn into the through-holes under negative pressure and completely fill them. After filling, the substrate is allowed to stand for a period of time to allow the conductive paste to fully level within the through-holes and blind grooves, eliminating any air bubbles and voids that may have been introduced during the filling process.

[0030] In one embodiment, both the debinding process and the co-firing are performed in a protective atmosphere; the co-firing temperature is above the softening point of the glass substrate and below the full flow temperature of the glass substrate.

[0031] The protective atmosphere is a nitrogen or inert gas atmosphere to prevent the metal components in the conductive paste from oxidizing during heating, thus ensuring the conductivity of the conductor after sintering. The co-firing temperature is set above the softening point of the glass substrate but below its full flow temperature; the softening point of the glass refers to the point at which the glass begins to soften and deform significantly during heating, and its viscosity decreases to approximately 10. 7.6 The temperature at which the glass viscosity further decreases to approximately 10; the complete flow temperature is the temperature at which the glass viscosity further decreases to approximately 10. 4 Up to 10 5 The viscosity of a glass substrate is the temperature at which it undergoes significant flow deformation under its own weight. Within this temperature range, the glass substrate is in a semi-softened state, which allows for fusion bonding between adjacent layers without excessive flow due to excessively low viscosity, thus maintaining the overall shape and integrity of the substrate and its circuit pattern.

[0032] In one embodiment, when the glass substrates are stacked, a positioning structure is provided between each layer of the glass substrates to ensure that the through holes on different layers of the glass substrates are aligned in the thickness direction; the circuit patterns on each layer of the glass substrates may be the same or different.

[0033] The positioning structure can be a positioning mark, positioning pin hole, or optical alignment mark located on the edge of the glass substrate. It ensures that the through-holes on different layers of the glass substrate are aligned in the thickness direction through visual recognition or mechanical positioning, allowing the conductive paste within each through-hole to connect vertically after co-firing, forming a continuous vertical interconnect channel. The circuit patterns on each layer of the glass substrate can be the same or different, depending on the functional design of the multilayer circuit. Signal conduction between different layers is achieved through through-holes.

[0034] In one embodiment, the cross-sectional shape of the blind slot is any one of a rectangle, a semi-circle, or a trapezoid; the conductive paste filled in the blind slot is any one of a resistive paste, a capacitive paste, or an inductive paste, so as to achieve in-layer integration of embedded passive devices.

[0035] This solution further expands the functional integration capability based on the aforementioned blind slot structure. By selectively filling the blind slot with functional pastes with different electrical properties, embedded passive devices such as resistors, capacitors, or inductors are formed after debinding and co-firing. This allows for the direct in-layer integration of passive devices within the glass substrate without the need for additional surface mount processes.

[0036] In one embodiment, the following steps are also included: Step 5: Flatten the surface of the multilayer co-fired glass substrate and finally cut off the edges.

[0037] A multilayer glass substrate, manufactured using the above-described method for preparing a multilayer glass substrate, comprises at least two pre-formed glass substrates. The interface between two adjacent glass substrates is a glass-glass fusion bonding interface formed by co-firing. Each glass substrate has a through-hole extending through its thickness direction. A sintered conductor is disposed within the through-hole. Vertical electrical interconnection is achieved between different glass substrates through the sintered conductor.

[0038] In this structure, the interface between the sintered conductor and the glass substrate is a mechanical interlocking interface formed during the co-firing process, resulting in high bonding strength.

[0039] At least one surface of the glass substrate is provided with a blind groove, and the blind groove is filled with a sintered conductive body or a functional paste sintered body, wherein the functional paste sintered body is any one of a resistor, a capacitor or an inductor.

[0040] When the blind trench is filled with conductive paste, the sintered conductors within the blind trench achieve electrical wiring on the same surface. When the blind trench is filled with functional paste, the sintered functional paste can be any one of a resistor, capacitor, or inductor, thereby achieving in-layer integration of embedded passive devices. This multilayer glass substrate achieves both precise conductor routing and allows for high current flow, while integrating multiple functions to meet the demands of advanced electronic packaging for high-density integration and multifunctionality.

[0041] The present invention will be further described in detail below with reference to embodiments, but the embodiments of the present invention are not limited thereto. The glass substrate, conductive paste and other raw materials used in the following embodiments can all be obtained commercially, and the laser cutting machine, heating furnace, grinding equipment and other equipment used are all conventional equipment known in the art.

[0042] Example 1 This embodiment provides a method for preparing a multilayer co-fired glass substrate (MLCG), which specifically includes the following steps.

[0043] (1) Glass substrate preparation and through-hole formation Four Corning AF32 glass substrates are provided, with dimensions of 50mm × 50mm × 0.32mm.

[0044] Each glass substrate is subjected to double-sided laser irradiation using a picosecond laser cutting machine, causing localized modification of the substrate. Forty through-holes are machined on each glass substrate, with a hole diameter of φ60μm and a hole spacing of 400μm.

[0045] Four glass substrates with drilled holes were immersed in a hydrofluoric acid (HF) etching solution and subjected to ultrasonic vibration treatment. The volume ratio of HF to water was 1:4. By utilizing the difference in etching rate between the modified and unmodified regions in the HF etching solution, the glass material in the modified regions was selectively removed, forming through holes that penetrated the thickness direction of the glass substrates.

[0046] (2) Filling and desizing of conductive paste Electronic copper paste is filled into the through-holes of a glass substrate using a combination of printing and low-vacuum adsorption processes. After filling, the glass substrate is left to stand for 3 hours to allow the electronic copper paste to fully level within the through-holes.

[0047] After standing, the four glass substrates were placed separately in a nitrogen-protected furnace for desizing. The desizing temperature was 360°C and the holding time was 60 minutes to remove organic matter from the electronic copper paste.

[0048] (3) Multilayer stacking and co-firing Four glass substrates, after being de-adhesive treated, are stacked along their thickness direction to form a composite. Each glass substrate has a positioning structure that aligns with each other to ensure that the through holes on different glass substrates are accurately aligned in the thickness direction.

[0049] The stacked substrates were co-fired in a nitrogen-protected furnace at 920°C for 20 minutes. During co-firing, the interfaces of adjacent glass substrates fused together, and the copper paste within the vias was sintered to form sintered conductors, achieving vertical electrical interconnection between layers.

[0050] (4) Surface smoothing The surface of the co-fired multilayer co-fired glass substrate is planarized using chemical mechanical polishing (CMP) equipment, and irregular edges and corners are removed to obtain the finished multilayer co-fired glass substrate.

[0051] (5) Performance testing The performance of the multilayer co-fired glass substrate prepared in this embodiment was tested, and the results are shown in Table 1.

[0052] Table 1. Properties of the multilayer co-fired glass substrates prepared in Example 1

[0053] Example 2 This embodiment provides another method for preparing a multilayer co-fired glass substrate, which specifically includes the following steps.

[0054] (1) Glass substrate preparation, through-hole formation and blind groove processing Five Corning AF32 glass substrates are provided, with dimensions of 50mm × 50mm × 0.32mm.

[0055] Each glass substrate is subjected to double-sided laser irradiation using a picosecond laser cutting machine, causing localized modification of the substrate. Sixty through-holes are machined on each glass substrate, with a hole diameter of φ100μm and a hole spacing of 500μm.

[0056] A blind groove with a width of 0.1 mm and a depth of 0.1 mm is processed on the surface of a glass substrate using a laser cutting machine, so that 20 through holes can be interconnected through the blind groove.

[0057] Five glass substrates containing through-holes and blind trenches were immersed in HF etching solution and subjected to ultrasonic vibration treatment. The volume ratio of HF to water was 1:4. The glass material in the modified area was selectively removed to form through-holes and blind trenches.

[0058] (2) Filling and desizing of conductive paste By combining printing technology with low-vacuum adsorption technology, electronic silver paste is simultaneously filled into the vias and blind trenches of a glass substrate. After filling, the glass substrate is left to stand for 3 hours to allow the electronic silver paste to fully level within the vias and blind trenches.

[0059] Five glass substrates, after being left to stand, were placed separately in a nitrogen-protected furnace for desizing. The desizing temperature was 300°C and the holding time was 120 minutes to remove organic matter from the electronic silver paste.

[0060] (3) Multilayer stacking and co-firing Five glass substrates, after being de-adhesive-treated, are stacked along their thickness direction using a positioning device to form a composite material. The circuit patterns on each glass substrate are set according to preset interconnection requirements to ensure electrical interconnection channels between upper and lower layers.

[0061] The stacked substrates were co-fired in a nitrogen-protected furnace at 900°C for 35 minutes. During co-firing, the interfaces of adjacent glass substrates fused together, and the silver paste in the vias and blind trenches was sintered to form sintered conductors, achieving vertical electrical interconnection and planar wiring between layers.

[0062] (4) Surface smoothing The surface of the co-fired multilayer co-fired glass substrate is planarized using CMP equipment, and irregular edges and corners are removed.

[0063] (5) Performance testing The performance of the multilayer co-fired glass substrate prepared in this embodiment was tested, and the results are shown in Table 2.

[0064] Table 2. Properties of the multilayer co-fired glass substrates prepared in Example 2

[0065] Example 3 This embodiment is used to verify the filling effect of the present invention under ultra-high aspect ratio conditions.

[0066] (1) Glass substrate preparation and through-hole formation Three Schott BOROFLOAT® 33 glass substrates are provided, with dimensions of 50mm × 50mm × 0.5mm.

[0067] Each glass substrate is subjected to double-sided laser irradiation using a femtosecond laser cutting machine, causing localized modification of the glass substrate. Sixty through-holes with a diameter of φ20μm are machined on each glass substrate. The glass substrate thickness is 0.5mm, and the aspect ratio of the through-holes is 100:1.

[0068] The three glass substrates with holes were immersed in HF etching solution and stirred for etching. The volume ratio of HF to water was 1:6. The glass material in the modified area was selectively removed to form through holes that penetrate the thickness direction of the glass substrate.

[0069] (2) Filling and desizing of conductive paste A combination of printing and low-vacuum adsorption processes was used to fill the through-holes of a glass substrate with nano-silver paste (silver particle size ≤200nm). After filling, the glass substrate was left to stand for 5 hours to allow the nano-silver paste to fully level within the through-holes.

[0070] After standing, the three glass substrates were placed separately in a nitrogen-protected furnace for desizing. The desizing temperature was 320℃ and the holding time was 90 minutes to remove organic matter from the nano silver paste.

[0071] (3) Multilayer stacking and co-firing Three glass substrates, after being de-adhesive treated, are stacked along the thickness direction to form a stack. The positioning structure between each glass substrate layer ensures that the through holes are accurately aligned in the thickness direction.

[0072] The stack was placed in a nitrogen-protected furnace for co-firing at a temperature of 880°C for 30 minutes.

[0073] (4) Surface smoothing The surface of the co-fired multilayer co-fired glass substrate is planarized using CMP equipment.

[0074] (5) Performance testing The performance of the multilayer co-fired glass substrate prepared in this embodiment was tested, and the results are shown in Table 3.

[0075] Table 3. Properties of the multilayer co-fired glass substrates prepared in Example 3

[0076] This embodiment demonstrates that the present invention, through the paste printing filling method, can overcome the bottleneck of traditional electroplating hole filling being limited by the aspect ratio (the aspect ratio of traditional electroplating is generally ≤5:1), and achieve reliable filling of through holes with an ultra-high aspect ratio of 100:1.

[0077] Comparative Example 1 This comparative example uses a traditional TGV sputtering + electroplating route to prepare a glass substrate, and is used for comparison with Example 1 of the present invention.

[0078] (1) Preparation process The same glass substrate (Corning AF32, 50mm × 50mm × 0.32mm) and vias of the same specifications (φ60μm, 40 holes / piece) as in Example 1 were used. The fabrication process followed the conventional TGV process: LIDE etching to form vias → plasma activation → magnetron sputtering of Ti / Cu seed layer → photolithography → pulse electroplating to fill vias → CMP polishing → RDL photolithography + electroplating + etching → bump fabrication + temporary bonding of bottom RDL + debonding, totaling 9 steps.

[0079] (2) Performance comparison The performance comparison between Example 1 and Comparative Example 1 is shown in Table 4.

[0080] Table 4 Performance Comparison of Example 1 and Comparative Example 1

[0081] The results show that, compared with the traditional TGV sputtering + electroplating route, the present invention simplifies the process, significantly reduces costs, greatly improves adhesion, and provides better warpage control.

[0082] Comparative Example 2 This comparative example is used to verify the necessity of the co-firing step in this invention.

[0083] The process conditions were exactly the same as in Example 1, except that after stacking four glass substrates that had undergone de-adhesion treatment, they were not co-fired at 920°C, but the stacked body was simply cooled under pressure at room temperature.

[0084] (1) Results There is no glass-to-glass bonding between the layers, the stack is loose, and the interlayer tensile strength is <0.5 N / cm. There is no electrical interconnection between the copper paste inside the through-hole and the upper and lower layers.

[0085] (2) Conclusion This comparative example demonstrates that without co-firing, it is impossible to achieve integrated bonding and interlayer electrical interconnection of multilayer glass substrates. Therefore, "co-firing at a temperature above the softening point of the glass substrate" is an essential technical feature for achieving the objectives of this invention.

[0086] The multilayer co-fired glass substrate fabrication method provided by this invention can be widely applied in advanced electronic packaging, Mini-LED / Micro-LED, biomedicine, consumer electronics, and other fields. Compared with traditional TGV technology, this invention simplifies the process, reduces costs, achieves a breakthrough in aspect ratio, significantly improves bonding strength, and provides excellent warpage control, demonstrating promising industrial application prospects and economic benefits.

[0087] Any aspects of this invention not described in detail are well-known to those skilled in the art.

[0088] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a multilayer glass substrate, characterized in that, Includes the following steps: Step 1: Provide a pre-formed glass substrate and form a through hole in the glass substrate that extends through its thickness direction; Step 2: Fill the through holes with conductive paste and perform a desmearing process on the glass substrate after filling to remove organic matter from the conductive paste; Step 3: Stack at least two glass substrates, after the adhesive removal process, along the thickness direction to form a stacked body; Step 4: The superimposed body is co-fired at a temperature above the softening point of the glass substrate, so that the interfaces of adjacent glass substrates are fused together, and the conductive paste in the through hole forms interlayer vertical interconnection channels after sintering, thus forming a multilayer co-fired glass substrate.

2. The method for preparing a multilayer glass substrate according to claim 1, characterized in that, After forming the through hole, the method further includes the step of forming a blind groove on at least one surface of the glass substrate; the conductive paste is simultaneously filled into the through hole and the blind groove.

3. The method for preparing a multilayer glass substrate according to claim 1, characterized in that, The via is formed by: using a laser to modify a local area of ​​the glass substrate, and then selectively removing the glass material in the modified area with an etching solution; The etching solution is a hydrofluoric acid etching solution.

4. The method for preparing a multilayer glass substrate according to claim 1, characterized in that, The conductive paste is a copper-based electronic paste or a silver-based electronic paste; the conductive paste is filled by a combination of printing and vacuum adsorption processes.

5. The method for preparing a multilayer glass substrate according to claim 1, characterized in that, Both the debinding process and the co-firing are carried out in a protective atmosphere; the co-firing temperature is above the softening point of the glass substrate and below the full flow temperature of the glass substrate.

6. The method for preparing a multilayer glass substrate according to claim 1, characterized in that, When the glass substrates are stacked, positioning structures are provided between each layer of glass substrates to ensure that the through holes on different layers of glass substrates are aligned in the thickness direction; the circuit patterns on each layer of glass substrates may be the same or different.

7. The method for preparing a multilayer glass substrate according to claim 2, characterized in that, The cross-sectional shape of the blind slot can be any one of rectangle, semi-circle or trapezoid; the conductive paste filled in the blind slot can be any one of resistive paste, capacitive paste or inductive paste, so as to realize the in-layer integration of embedded passive devices.

8. The method for preparing a multilayer glass substrate according to claim 1, characterized in that, It also includes the following steps: Step 5: Flatten the surface of the multilayer co-fired glass substrate and finally cut off the edges.

9. A multilayer glass substrate, manufactured using the multilayer glass substrate preparation method according to any one of claims 1 to 8, characterized in that, It includes at least two pre-formed glass substrates, the interface between two adjacent glass substrates is a glass-glass fusion bonding interface formed by co-firing, each glass substrate has a through hole extending through its thickness direction, and a sintered conductor is provided in the through hole, and vertical electrical interconnection is achieved between different glass substrates through the sintered conductor.

10. A multilayer glass substrate according to claim 9, characterized in that, At least one surface of the glass substrate is provided with a blind groove, and the blind groove is filled with a sintered conductive body or a functional paste sintered body, wherein the functional paste sintered body is any one of a resistor, a capacitor or an inductor.

Images