A ceramic package base and a method for manufacturing the same

Abstract

The application discloses a ceramic packaging base and a preparation method thereof, and relates to the technical field of electronic elements. The application provides a ceramic packaging base, which comprises a ceramic layer and a conductive layer, and the ceramic layer and the conductive layer are adjacent; raw materials of the ceramic layer comprise ceramic slurry, and the ceramic slurry comprises the following components: ceramic powder A, a photoinitiator A, a plasticizer A, a dispersing agent A and a photosensitive resin A; raw materials of the conductive layer comprise conductive slurry, and the conductive slurry comprises the following components: metal powder, ceramic powder B, a photoinitiator B, a plasticizer B, a dispersing agent B and a photosensitive resin B; in the conductive slurry, the weight ratio of the ceramic powder B to the metal powder is (0.05-0.25):1. The ceramic packaging base prepared by the application has high forming precision and will not have problems such as warping, cracking, machining deformation and the like.

Description

Technical Field

[0001] This invention relates to the field of electronic component technology, and in particular to a ceramic packaging substrate and its preparation method. Background Technology

[0002] Ceramic materials are widely used in the fabrication of packaging substrates for chips, crystal oscillators, surface acoustic wave filters, and high-power LEDs due to their excellent properties such as high temperature resistance, wear resistance, and corrosion resistance. Typically, ceramic packaging substrates require the connection of metal components and the printing of metal circuit patterns to achieve specific functions. Existing methods for fabricating ceramic packaging substrates usually involve processes such as cavity punching, lamination, grooving, plating, etching, and sintering. These processes are complex, time-consuming, and the ceramic substrate is prone to deformation, hindering miniaturization. Furthermore, when fabricating metal circuits for complex ceramic structures (e.g., ceramic packaging substrates for temperature-compensated crystal oscillators), interference from the existing ceramic structure often increases the difficulty of fabricating the metal circuits.

[0003] Using 3D printing technology to manufacture ceramic packaging bases is a novel approach. However, when applying the above method to the preparation of ceramic packaging bases, there are problems such as material incompatibility and mismatch, which can lead to warping and cracking of the products. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to overcome the shortcomings of the prior art and provide a ceramic encapsulation substrate and its preparation method.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a ceramic encapsulation substrate, comprising a ceramic layer and a conductive layer, wherein the ceramic layer and the conductive layer are adjacent; the raw material of the ceramic layer comprises a ceramic slurry, wherein the ceramic slurry comprises the following components: ceramic powder A, photoinitiator A, plasticizer A, dispersant A, and photosensitive resin A; the raw material of the conductive layer comprises a conductive slurry, wherein the conductive slurry comprises the following components: metal powder, ceramic powder B, photoinitiator B, plasticizer B, dispersant B, and photosensitive resin B; wherein the weight ratio of ceramic powder B to metal powder in the conductive slurry is (0.05-0.25):1.

[0006] This invention innovatively employs a multi-material photopolymerization molding method to prepare ceramic packaging substrates. By adjusting the formulation of conductive paste and ceramic paste, the two materials exhibit good compatibility, consistent curing behavior, and high molding precision. Furthermore, it avoids problems such as warping, cracking, and processing deformation, making it more conducive to the preparation of high-precision, miniaturized ceramic packaging substrates.

[0007] After extensive experimental research, the inventors discovered that by adding a specific amount of ceramic powder B to the conductive slurry, this invention can reduce the absorbance of the conductive slurry and improve its overall curing ability without affecting its conductivity. If the weight ratio of ceramic powder B to metal powder is too low, it is insufficient to reduce the absorbance of the conductive slurry and improve its curing ability, leading to poor molding accuracy, a high cracking rate, and a high warpage rate in the product. Conversely, if the weight ratio of ceramic powder B to metal powder is too high, it will affect the conductivity of the slurry.

[0008] In addition, ceramic powder B in the conductive paste remains in the conductive layer of the product after sintering. This ceramic powder B can also make the thermal expansion coefficients of the ceramic layer and the conductive layer closer, making the connection between the ceramic layer and the metal tighter, and avoiding interlayer cracking and warping when the temperature changes drastically.

[0009] Preferably, the ceramic slurry comprises the following components in parts by weight: 60-95 parts ceramic powder A, 1-5 parts photoinitiator A, 1-20 parts plasticizer A, 1-6 parts dispersant A, and 5-40 parts photosensitive resin A.

[0010] Preferably, the conductive paste comprises the following components in parts by weight: 40-90 parts of metal powder, 3-20 parts of ceramic powder B, 1-6 parts of photoinitiator B, 1-20 parts of plasticizer B, 1-6 parts of dispersant B, and 10-60 parts of photosensitive resin B.

[0011] Preferably, the weight percentage of plasticizer A in the ceramic slurry and the weight percentage of plasticizer B in the conductive slurry are 1:(1-4); more preferably, the weight percentage of plasticizer A in the ceramic slurry and the weight percentage of plasticizer B in the conductive slurry are 1:(1.5-2.5).

[0012] After extensive experimental research, the inventors discovered that by controlling the amount of the plasticizer within the above-mentioned range, this invention can improve the bonding force between the cured conductive paste and the ceramic paste, further mitigating cracking and warping issues. When the weight ratio is higher or lower than the above range, the rheological properties of the ceramic paste and the conductive paste are inconsistent, resulting in inconsistent shrinkage behavior during the formation of the ceramic encapsulation substrate, and an increase in the cracking and warping rates of the product.

[0013] Preferably, the weight percentage of photosensitive resin A in the ceramic slurry and the weight percentage of photosensitive resin B in the conductive slurry are in the ratio of 1:(1-4); more preferably, the weight percentage of photosensitive resin A in the ceramic slurry and the weight percentage of photosensitive resin B in the conductive slurry are in the ratio of 1:(1.5-2).

[0014] After extensive experimental research, the inventors discovered that by controlling the amount of photosensitive resin within the above-mentioned range, this invention can improve molding accuracy. Because ceramic and metal powders have different absorbance, light attenuates differently in ceramic and conductive slurries. By controlling the ratio of photosensitive resin in the ceramic and conductive slurries, the curing speeds of the two slurries can be kept relatively consistent, thereby improving material compatibility and further enhancing molding accuracy.

[0015] Preferably, the ceramic encapsulation base satisfies at least one of the following (a)-(f):

[0016] (a) The metal powder includes at least one of tungsten powder, molybdenum powder, and manganese powder;

[0017] (b) The ceramic powder A and ceramic powder B include at least one of alumina, zirconium oxide, aluminum nitride, and silicon nitride; more preferably, the ceramic powder A and ceramic powder B are alumina;

[0018] (c) The photoinitiator A and photoinitiator B include at least one of 2-dimethylamino-2-benzyl-1-(4-piperbutylphenyl)-1-butanone, 1-hydroxycyclohexylbenzophenone, 4,4-bis(diethoxy)benzophenone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 2-isopropylthioxanthrone;

[0019] (d) Plasticizer A and plasticizer B include at least one of polyethylene glycol, oleic acid, tributyl citrate, trioctyl citrate, glycerin, dioctyl phthalate, and dibutyl phthalate;

[0020] (e) The dispersant A and dispersant B include at least one of toluene, acetone, and isopropanol;

[0021] (f) The photosensitive resin A and photosensitive resin B include at least one of epoxy acrylate oligomer, polyester acrylate oligomer, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and 1,6-hexanediol diacrylate.

[0022] Preferably, the ceramic encapsulation base of the present invention is prepared by photopolymerization molding.

[0023] The present invention also provides a method for preparing the ceramic encapsulation substrate, comprising the following steps:

[0024] (1) Ceramic slurry and conductive slurry were prepared;

[0025] (2) The ceramic slurry and conductive slurry are respectively loaded into the material tank of the photopolymerization printer, and the preparation process is controlled by the program according to the designed ceramic encapsulation base model.

[0026] (3) The ceramic slurry is laid to obtain a ceramic layer, which is then cured by light irradiation; the conductive slurry is laid to obtain a conductive layer, which is then cured by light irradiation.

[0027] Alternatively, the ceramic slurry is laid to obtain a ceramic layer, the conductive slurry is laid to obtain a conductive layer, and the layer is cured by light irradiation.

[0028] (4) Repeat step (3) to photopolymerize and print the ceramic layer and conductive layer to form a blank of the ceramic encapsulation base;

[0029] (5) The ceramic encapsulation base is obtained by drying, debinding and sintering the blank.

[0030] Preferably, in step (4), the process parameters for photopolymerization printing of the ceramic layer are: single-layer exposure thickness of 10-50 μm and single-layer exposure time of 1-10 s; more preferably, the process parameters for photopolymerization printing of the ceramic layer are: single-layer exposure thickness of 20-40 μm and single-layer exposure time of 2-3 s.

[0031] In step (4), the process parameters for photopolymerization printing of the conductive layer are: single-layer exposure thickness 10-50μm, single-layer exposure time 1-10s; more preferably, the process parameters for photopolymerization printing of the conductive layer are: single-layer exposure thickness 10-20μm, single-layer exposure time 4-6s.

[0032] Preferably, the ratio of the exposure thickness of the ceramic layer to the exposure thickness of the conductive layer is (1-4):1, and the ratio of the exposure time of the ceramic layer to the exposure time of the conductive layer is (0.3-0.7):1; preferably, the ratio of the exposure thickness of the ceramic layer to the exposure thickness of the conductive layer is (1.5-2.5):1, and the ratio of the exposure time of the ceramic layer to the exposure time of the conductive layer is (0.4-0.6):1.

[0033] Preferably, in step (4), the squeegee height during photocuring printing of the ceramic layer is 3-5 times the single-layer exposure thickness, and the squeegee speed is 100-350 mm / s; the squeegee height during photocuring printing of the conductive layer is 3-5 times the single-layer exposure thickness, and the squeegee speed is 50-350 mm / s; preferably, the squeegee speed during photocuring printing of the ceramic layer is 150-200 mm / s, and the squeegee speed during photocuring printing of the conductive layer is 100-130 mm / s.

[0034] After extensive experimentation, the inventors discovered that due to the different absorbance of ceramic and conductive pastes, it is necessary to rationally control the exposure thickness and exposure time during preparation. Single-layer exposure thickness refers to the thickness of a single layer slice in the software. The printer platform will adjust the thickness upwards by this value after each layer is printed. If this value is higher than the actual curing depth, the next layer will not adhere well to the previous layer; similarly, insufficient exposure time will also lead to poor adhesion. Therefore, by rationally controlling the ratio of exposure thickness to exposure time for the two pastes, the curing behavior of the two materials can be made consistent, improving molding accuracy.

[0035] Compared to existing technologies, the advantages of this invention are as follows: This invention innovatively employs a multi-material photopolymerization molding method to prepare ceramic packaging substrates. By adjusting the formulation composition of the conductive paste and the ceramic paste, and controlling the process parameters during preparation, the two materials exhibit good compatibility, consistent curing behavior, and high molding precision, without causing problems such as warping, cracking, or processing deformation. This is beneficial for preparing high-precision, miniaturized ceramic packaging substrates. Detailed Implementation

[0036] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0037] This invention prepares the ceramic encapsulation substrate by adjusting the formulation composition of the conductive paste and ceramic paste and controlling the process parameters during preparation. The embodiments and comparative examples use an H-type TCXO encapsulation substrate as an example to specifically describe the implementation of this invention, but the invention is not limited to this application. Each embodiment or comparative example prepared one batch of 1000 products, and the following indicators were tested:

[0038] (1) Molding accuracy pass rate: The molding accuracy is evaluated by measuring the dimensions of the outer perimeter and inner cavity, the distance between the specific electrode or boss structure and the inner cavity, and comparing them with the design dimensions of the structural part model. The difference between the measured dimensions and the design dimensions is considered to be within ±0.1mm. The percentage of qualified products in the same batch is used as the molding accuracy pass rate. The pass rate of a batch of products should be above 95%.

[0039] (2) Cracking rate: The appearance of electronic structural components is observed under a microscope, and the percentage of cracked electronic structural components in the same batch of products is counted. A cracking rate of 0-0.01% is considered acceptable.

[0040] (3) Warpage ratio: Place the porcelain body on a flat surface and measure the maximum gap width between the porcelain body and the surface. A maximum gap width between the porcelain body and the surface of less than 0.1 mm is considered acceptable. The percentage of products with unacceptable warpage in the same batch is counted as the warpage ratio. The warpage ratio of a batch of products should be less than 0.5%.

[0041] (4) Wiring resistance: The wiring resistance between the various metal parts of the product is tested by a flying probe tester. The wiring resistance of the parts that are designed to be electrically connected should be less than (10Ω). If the wiring resistance is too high, it will affect the electrical connection and may even cause an open circuit problem.

[0042] Examples 1-17 and Comparative Examples 1-3

[0043] Example 1

[0044] In the process of preparing the H-type TCXO packaging substrate in Embodiment 1 of the present invention, the preparation method is as follows:

[0045] (1) Ceramic slurry and conductive slurry were prepared;

[0046] (2) The ceramic slurry and conductive slurry are respectively loaded into the material tank of the photopolymerization printer, and the preparation process is controlled by the program according to the designed ceramic encapsulation base model.

[0047] (3) The ceramic slurry is laid to obtain a ceramic layer, which is then cured by light irradiation; the conductive slurry is laid to obtain a conductive layer, which is then cured by light irradiation.

[0048] (4) Repeat step (3) to photopolymerize and print the ceramic layer and conductive layer to form a blank of the ceramic encapsulation base;

[0049] (5) The ceramic encapsulation base is obtained by drying, debinding and sintering the blank.

[0050] The preparation methods of the ceramic packaging substrates provided in the embodiments and comparative examples of this invention are the same as those in Example 1, except for the formulation composition and dosage of the conductive paste and ceramic paste, as well as the process parameters for controlling the preparation process. Specific parameters for Examples 1-17 and Comparative Examples 1-2 are shown in Tables 1-3. In this embodiment, the thickness of each ceramic layer in the H-type TCXO packaging substrate green body is uniformly 0.24 mm, and the thickness of the conductive layer is uniformly 50 μm. However, the single-layer exposure thickness of the ceramic / conductive layer varies in each embodiment or comparative example. When the green body ceramic / conductive layer thickness cannot be divided by the single-layer exposure thickness, the exposure thickness of the last exposure is modified to meet product requirements.

[0051] Comparative Example 3 was prepared using a traditional method instead of a photocuring method, and the steps included:

[0052] 1. Cast ceramic slurry into ceramic green sheets. The ceramic slurry, by weight, includes 80 parts Al2O3, 6 parts resin binder (specifically, acrylic resin PMMA), 5 parts plasticizer (dioctyl phthalate DOP), 6 parts solvent (isopropanol), and 3 parts dispersant (stearic acid). Punch and fill holes, and print metal wiring. The slurry used for metal wiring, by weight, includes 60 parts metal powder (tungsten-molybdenum mass ratio 7:3), 10 parts ceramic powder (Al2O3), 6 parts resin binder (ethyl cellulose), 5 parts plasticizer (dioctyl phthalate DOP), and 6 parts solvent (isopropanol).

[0053] 2. Stack the ceramic green sheets with printed metal wires into a ceramic body;

[0054] 3. Plate a nickel layer onto the metal wiring;

[0055] 4. The ceramic body is sintered to obtain the encapsulation base.

[0056] The test results of Examples 1-17 and Comparative Examples 1-3 are shown in Table 4.

[0057] Table 1

[0058]

[0059]

[0060] Table 2

[0061]

[0062]

[0063]

[0064] Table 3

[0065]

[0066]

[0067] Table 4

[0068]

[0069]

[0070] As shown in the table above, the ceramic packaging bases prepared in the embodiments of the present invention all meet the following indicators: the molding accuracy qualification rate is above 95%, the cracking ratio is 0, the warping ratio is less than 0.5%, and the wiring resistance is less than 10Ω.

[0071] The weight percentage of plasticizer A in the ceramic slurry and the weight percentage of plasticizer B in the conductive slurry described in Examples 10 and 11 of this invention are not within the specific range of 1:(1-4) of this invention, which leads to an increase in the degree of inconsistency in shrinkage behavior during photocuring and an increase in the proportion of cracking and warping.

[0072] In Examples 12 and 13 of this invention, the weight percentage of photosensitive resin A in the ceramic slurry and the weight percentage of photosensitive resin B in the conductive slurry are not within the specific range of 1:(1-4) of this invention, resulting in a slight difference in the curing rate of the ceramic layer and the conductive layer, and an increase in the proportion of cracking and warping.

[0073] In Embodiments 14 and 15 of this invention, the ratio of the exposure thickness of the ceramic layer to the exposure thickness of the conductive layer is not within the specific range of (1-4):1 of this invention, resulting in a slight difference in the curing rate of the ceramic layer and the conductive layer, and an increase in the proportion of cracking and warping.

[0074] In Embodiments 16 and 17 of this invention, the ratio of the exposure time of the ceramic layer to the exposure time of the conductive layer is not within the specific range of (0.3-0.7):1 of this invention, resulting in a slight difference in the curing rate of the ceramic layer and the conductive layer, and an increase in the proportion of cracking and warping.

[0075] In Comparative Example 1, the ratio of ceramic powder B to metal powder in the conductive paste did not meet the specific range (0.05-0.25:1) of this invention, resulting in excessive light absorption of the conductive paste, inconsistent curing behavior between the conductive paste and the ceramic paste, and unqualified data such as cracking ratio, molding accuracy pass rate, and warpage ratio. In Comparative Example 2, the ratio of ceramic powder B to metal powder in the conductive paste exceeded the specific range (0.05-0.25:1) of this invention, resulting in low conductivity of the paste and unqualified wiring resistance.

[0076] Comparative Example 3, which uses a traditional method instead of a photocuring method, produced a packaging substrate with a molding accuracy pass rate of 89.9%, a cracking rate of 0.09, a warping rate of less than 0.1, and a wiring resistance of less than 5Ω, which was considered unqualified.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A ceramic encapsulation base, characterized in that, It includes a ceramic layer and a conductive layer, wherein the ceramic layer and the conductive layer are adjacent to each other; The raw materials for the ceramic layer include a ceramic slurry, which comprises the following components: ceramic powder A, photoinitiator A, plasticizer A, dispersant A, and photosensitive resin A; the raw materials for the conductive layer include a conductive slurry, which comprises the following components: metal powder, ceramic powder B, photoinitiator B, plasticizer B, dispersant B, and photosensitive resin B. In the conductive slurry, the weight ratio of ceramic powder B to metal powder is (0.05-0.25):1; The method for preparing the ceramic encapsulation substrate includes the following steps: (1) Ceramic slurry and conductive slurry were prepared; (2) The ceramic slurry and conductive slurry are respectively loaded into the material tank of the photopolymerization printer, and the preparation process is controlled by the program according to the designed ceramic encapsulation base model; (3) The ceramic slurry is laid to obtain a ceramic layer, which is then cured by light irradiation; the conductive slurry is laid to obtain a conductive layer, which is then cured by light irradiation. Alternatively, the ceramic slurry is laid to obtain a ceramic layer, the conductive slurry is laid to obtain a conductive layer, and the layer is cured by light irradiation. (4) Repeat step (3) to photopolymerize and print the ceramic layer and the conductive layer to form a blank of the ceramic encapsulation base; the process parameters for photopolymerization printing of the ceramic layer are: single layer exposure thickness 10-50μm, single layer exposure time 1-10s; the process parameters for photopolymerization printing of the conductive layer are: single layer exposure thickness 10-50μm, single layer exposure time 1-10s; the ratio of the exposure thickness of the ceramic layer to the exposure thickness of the conductive layer is (1-4):1, and the ratio of the exposure time of the ceramic layer to the exposure time of the conductive layer is (0.3-0.7):1; (5) The ceramic encapsulation base blank is dried, debonded, and sintered to obtain the ceramic encapsulation base.

2. The ceramic encapsulation base as described in claim 1, characterized in that, The ceramic slurry comprises the following components in parts by weight: 60-95 parts ceramic powder A, 1-5 parts photoinitiator A, 1-20 parts plasticizer A, 1-6 parts dispersant A, and 5-40 parts photosensitive resin A.

3. The ceramic encapsulation base as described in claim 1, characterized in that, The conductive paste comprises the following components in parts by weight: 40-90 parts of metal powder, 3-20 parts of ceramic powder B, 1-6 parts of photoinitiator B, 1-20 parts of plasticizer B, 1-6 parts of dispersant B, and 10-60 parts of photosensitive resin B.

4. The ceramic encapsulation base as described in claim 1, characterized in that, The weight percentage of plasticizer A in the ceramic slurry and the weight percentage of plasticizer B in the conductive slurry are 1:(1-4).

5. The ceramic encapsulation base as described in claim 4, characterized in that, The weight percentage of plasticizer A in the ceramic slurry and the weight percentage of plasticizer B in the conductive slurry are 1:(1.5-2.5).

6. The ceramic encapsulation base as described in claim 1, characterized in that, The weight percentage of photosensitive resin A in the ceramic slurry and the weight percentage of photosensitive resin B in the conductive slurry are 1:(1-4).

7. The ceramic encapsulation base as described in claim 6, characterized in that, The weight percentage of photosensitive resin A in the ceramic slurry and the weight percentage of photosensitive resin B in the conductive slurry are 1:(1.5-2).

8. The ceramic encapsulation base as described in claim 1, characterized in that, Satisfy at least one of the following (a)-(f): (a) The metal powder includes at least one of tungsten powder, molybdenum powder, and manganese powder; (b) The ceramic powder A and ceramic powder B include at least one of alumina, zirconium oxide, aluminum nitride, and silicon nitride; (c) The photoinitiator A and photoinitiator B include at least one of 2-dimethylamino-2-benzyl-1-(4-piperbutylphenyl)-1-butanone, 1-hydroxycyclohexylbenzophenone, 4,4-bis(diethoxy)benzophenone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 2-isopropylthioxanthraphenone; (d) Plasticizer A and plasticizer B include at least one of polyethylene glycol, oleic acid, tributyl citrate, trioctyl citrate, glycerin, dioctyl phthalate, and dibutyl phthalate; (e) The dispersant A and dispersant B include at least one of toluene, acetone, and isopropanol; (f) The photosensitive resin A and photosensitive resin B include at least one of epoxy acrylate oligomer, polyester acrylate oligomer, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and 1,6-hexanediol diacrylate.

9. The ceramic encapsulation base as described in claim 8, characterized in that, The ceramic powder A and ceramic powder B are aluminum oxide.

10. The ceramic encapsulation base as described in claim 1, characterized in that, In step (4), the process parameters for photopolymerization printing of the ceramic layer are: single-layer exposure thickness 20-40μm, single-layer exposure time 2-3s; the process parameters for photopolymerization printing of the conductive layer are: single-layer exposure thickness 10-20μm, single-layer exposure time 4-6s.

11. The ceramic encapsulation base as described in claim 10, characterized in that, The ratio of the exposure thickness of the ceramic layer to the exposure thickness of the conductive layer is (1.5-2.5):1, and the ratio of the exposure time of the ceramic layer to the exposure time of the conductive layer is (0.4-0.6):

1.

12. The ceramic encapsulation base as described in claim 1, characterized in that, In step (4), the height of the squeegee during the photocuring printing of the ceramic layer is 3-5 times the single-layer exposure thickness, and the squeegee speed is 100-350mm / s; the height of the squeegee during the photocuring printing of the conductive layer is 3-5 times the single-layer exposure thickness, and the squeegee speed is 50-350mm / s.

13. The ceramic encapsulation base as described in claim 12, characterized in that, The squeegee speed during the photocuring printing of the ceramic layer is 150-200 mm / s, and the squeegee speed during the photocuring printing of the conductive layer is 100-130 mm / s.

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