A method for manufacturing a ceramic package base

Abstract

The application relates to a preparation method of a ceramic packaging base, and belongs to the technical field of semiconductor manufacturing. The preparation method of the ceramic packaging base realizes traceless cutting of a ceramic green body through filling of a cavity by a flexible material and further through special double-blade cutters and cutting parameters, so that a ceramic packaging base with good precision and high appearance qualification rate can be obtained. The preparation method can meet the preparation of ceramic packaging bases with cavity structures of various sizes and structures, is simple in process and high in operability, and improves the qualification rate of products.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing technology, and specifically relates to a method for preparing a ceramic packaging substrate. Background Technology

[0002] As electronic devices become smaller and more complex, the requirements for their lifespan and precision are increasing. This necessitates mounting various types of electronic devices onto ceramic substrates and encapsulating them to ensure they are not affected by external environmental factors, extend their lifespan, and guarantee high-precision operation. This is known as ceramic packaged substrate (PKG), which is widely used in semiconductor packaging such as crystal oscillators, crystal resonators, and filters.

[0003] The ceramic encapsulation base is made by sequentially stacking ceramic green sheets with printed conductive patterns and punched conductive holes. When electroplating the entire structure and the total thickness of the product is relatively thin (not more than 1 mm), it is often used to form a pre-pressing groove, sinter, and then split the sheet to prepare a single PKG product. However, extra protrusions or burrs are often formed at the fracture point on the outside. If the product is relatively thick, it needs to be cut into individual pieces before electroplating. To ensure complete cutting, the cutting tool needs to press down deeply enough, which can easily cause damage to the cutting equipment or the support platform. Especially for packaging bases with special cavity structures, such as the CSOP48 type packaging base used for gyroscope packaging, the CSOP type packaging base has asymmetrical cavities on the front and back, and its circuit is not connected in a conventional whole plate. It needs to be cut into individual packaging bases and then sintered. During the cutting and slicing process, due to the special cavity structure, the packaging base is very easy to deform, causing deviations in cavity size and cavity wall straightness. This leads to a decrease in the precision and appearance qualification rate of the packaged product, and further causes a significant reduction in service life.

[0004] Therefore, it is of great significance to develop a non-marking cutting method for packaging substrates with special cavity structures, so as to obtain ceramic packaging substrates with high precision and high appearance qualification rate. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems existing in the prior art and provide a method for preparing a ceramic encapsulation substrate.

[0006] This invention is achieved through the following technical solution:

[0007] This invention provides a method for preparing a ceramic encapsulation substrate, comprising the following steps:

[0008] (1) Take an integral ceramic green body, the front and back of the integral ceramic green body have cavities with asymmetrical structures, the internal volume of the cavity on the back is smaller than the internal volume of the cavity on the front, and place the integral ceramic green body with the back facing down.

[0009] (2) The back cavity is filled with a flexible material;

[0010] (3) Fix the ceramic green body after filling in step (2) with adhesive, confirm the initial cutting line position, and cut after positioning with a double-edged tool; the double-edged tool includes a double-angled tip and a blade body fixedly connected to the double-angled tip, the double-angled tip includes a tip A as the tip top and a tip B near the blade body, the edge of tip A and the vertical direction are at an angle of vertical inclination A; the edge of tip B and the vertical direction are at an angle of vertical inclination B; the vertical inclination angle A is smaller than the vertical inclination angle B;

[0011] The cutting process includes a first stage, a second stage, and a third stage; the first stage is from the contact between the tip of blade A and the ceramic green body until the contact between the tip of blade B and the ceramic green body; the second stage is from the contact between the tip of blade B and the ceramic green body until the contact between the parallel blade and the ceramic green body; the third stage is from the contact between the parallel blade and the ceramic green body until the cutting is completed.

[0012] (4) Remove the fixing adhesive and take out the flexible material to obtain a single ceramic encapsulation base green blank.

[0013] In conventional cutting processes, the deep-pressing tool completely fractures the product by applying pressure to both sides after the sharp blade cuts through the surface. This can cause compression on the green body itself. For ceramic green bodies with unconventional cavity structures, the top of the cavity is prone to collapse and twisting under pressure. This invention uses a flexible material to fill the back cavity, highly compensating for the unconventional cavity structure of the ceramic green body. The elastic deformation of the flexible material during cutting further fills the cavity, mitigating the dimensional or structural deformation of the ceramic green body caused by pressure. By providing sufficient support for the cavity structure, it ensures that there is no collapse or other adverse conditions during product cutting. On the other hand, the elastic deformation of the flexible material after being stressed fills the cavity. Compared to the traditional case where the green body has no bottom support plane, the flexible material filling the cavity also acts as a buffer to protect the cutting equipment and the support platform, resulting in ceramic parts with qualified dimensions, good appearance, and customizable special structures. Furthermore, the dual-angle blade tip design of this invention aims to achieve seamless cutting. Compared to the traditional single-blade tip cutting process, the gradual increase in angle at the blade tip makes it easier for the blade to penetrate the green blank during the initial cutting stage. The gradient cutting speed, combined with two different tilt angles, prevents defects such as protrusions, depressions, or deformation at the cut site, significantly improving the appearance of the finished product. For thicker green blanks, when the blade is pressed deep enough and the blade body contacts or enters the flexible material filling area, the deep penetration of the blade tip causes the flexible material to fill the cavity and envelop the blade body. The large angle design at the tail prevents difficulty in separating the blade. The process is simple and highly operable, improving the product's appearance qualification rate.

[0014] The integrated ceramic green body mentioned in step (1) of this invention can be a whole-plate integrated ceramic green body prepared by sequentially stacking ceramic green sheets with printed conductive patterns and punched conductive holes. The single ceramic encapsulation base green body obtained by the preparation method of this invention is then processed by conventional processes to obtain the ceramic encapsulation base product. The integrated ceramic green body in step (1) of this invention can be prepared by oneself or purchased. The preparation method of this invention does not require a specific type of integrated ceramic green body, as long as the integrated ceramic green body has cavities with asymmetrical structures on the front and back sides, it is suitable for the preparation method of this invention. The specific cavity shape can be designed according to actual needs. The preparation method of this invention can meet the cavity design requirements of various sizes and structures of integrated ceramic green bodies.

[0015] Preferably, in step (2), the volume of the flexible material accounts for 92% to 98% of the volume of the back cavity; more preferably, the volume of the flexible material accounts for 94% to 96% of the volume of the back cavity. The shape of the flexible material filling is consistent with the dimensional ratio of the internal shape of the back cavity; for example, the length-width-height ratio is consistent.

[0016] In step (2) of this invention, if the volume ratio of the flexible material filling is too small, the flexible material will not provide sufficient support for the complete plane of the cavity after filling, and will not be able to play an effective supporting role. That is, it will not be able to contact the upper surface blank and the lower surface platform simultaneously through elastic deformation. During the cutting process, the local structure in the cavity will be subjected to uneven stress, resulting in false pressure on the inner side of the cavity or collapse on the outer side, and a large deviation in the straightness of the side. If the volume ratio of the filling is too large, the flexible material will generate additional negative pressure on the inside of the cavity. This will increase the filling difficulty and affect the subsequent peeling of the flexible material, increase the peeling difficulty, and reduce the appearance qualification rate. Under the above volume ratio, the single ceramic encapsulation base green blank prepared by this invention has good flatness and appearance qualification rate.

[0017] Preferably, in step (2), the Shore hardness of the flexible material is 5 to 30 degrees; more preferably, the Shore hardness of the flexible material is 10 to 20 degrees.

[0018] When the hardness of the flexible material is too high, the insufficient buffering force inside the cavity during the cutting process will cause damage and cracking on the surface of the green blank, resulting in a decrease in flatness and straightness accuracy. On the other hand, if the hardness is too low, it will not be able to support the internal cavity, and problems such as collapse and accuracy deviation are likely to occur. The hardness of the flexible material within the above range can improve the pass rate of the single ceramic packaging base green blank.

[0019] Preferably, in step (2), the flexible material includes at least one of flexible silicone, flexible resin, and flexible hydrogel.

[0020] In this invention, the fixing adhesive serves two purposes: firstly, it fixes the green body and filler as a whole before cutting, facilitating the cutting process; secondly, after actual cutting, the green body is in a dispersed state, and the fixing adhesive can be used to bond and fix it, thus facilitating subsequent operations.

[0021] Preferably, in step (3), the vertical tilt angle A is 20° to 45°, the vertical length of the blade tip A is 0.02mm to 0.25mm, the vertical tilt angle B is 45° to 70°, and the vertical length of the blade tip B is 0.1mm to 0.5mm.

[0022] In this invention, the cutting tip A, which first contacts the green blank during cutting, is designed with a small angle. The maximum vertical tilt angle of A is no greater than the minimum vertical tilt angle of B. This results in low resistance per unit area, which has a smaller impact on the degree of green blank deformation and makes it easier for the cutting tool to enter the green blank. As the tilt angle of B increases, the gradient force further achieves a smooth cut of the green blank. If the tilt angle of A is too large, it is easy to cause edge warping, local twisting and deformation during the initial cutting. If the tilt angle of B is too small, it will affect the separation of subsequent cutting tools and affect the flatness and straightness of the side edges after cutting.

[0023] More preferably, the vertical tilt angle A is 25° to 40°, and the vertical length of the blade tip A is 0.05mm to 0.15mm; the vertical tilt angle B is 50° to 65°, and the vertical length of the blade tip B is 0.25mm to 0.35mm.

[0024] The thickness of the double-edged blade of the present invention can be adjusted according to the size of the green blank being cut, and the blade body of the double-edged blade can be a parallel blade body according to conventional settings.

[0025] Preferably, in step (3), the cutting speed of the first stage is less than the cutting speed of the second stage and less than the cutting speed of the third stage.

[0026] Preferably, in step (3), the cutting speed in the first stage is 0.67 mm / s to 2 mm / s, the cutting speed in the second stage is 2.5 mm / s to 3.5 mm / s, and the cutting speed in the third stage is 4 mm / s to 6.5 mm / s.

[0027] When the tip of blade A just touches the surface of the green blank, the first stage cutting speed needs to be kept uniform and slow in order to fully and seamlessly cut the outer surface of the green blank, and to create an initial kerf for subsequent cutting. The second stage cutting speed is greater than the first stage, with the aim of further widening the kerf at a faster speed, and changing the angle to accommodate the subsequent entry of the blade. In the third stage, the kerf already has a suitable angle. At this point, the speed is further increased to prevent internal ceramic compression pressure from being generated when the blade enters the interior of the green blank. Too slow a speed will aggravate deformation caused by pressure, while completing the third stage cutting process faster can shorten the time the inner wall is compressed, achieving a cutting with little or no deformation.

[0028] Specifically, in step (3), the fixing adhesive includes at least one of foam adhesive and UV adhesive.

[0029] In step (4) of the present invention, when the fixing adhesive is a foaming adhesive, the method for removing the fixing adhesive is to keep it at 150℃~250℃ for 10min~30min; when the fixing adhesive is a UV adhesive, the method for removing the fixing adhesive is to irradiate it under a UV lamp.

[0030] The present invention has the following beneficial effects: The method for preparing the ceramic packaging base of the present invention achieves traceless cutting of the ceramic green body by filling the cavity with flexible material and further using a special double-edged tool and cutting parameter settings, resulting in a ceramic packaging base with high precision and high appearance qualification rate. The preparation method of the present invention can meet the requirements for preparing ceramic packaging bases with cavity structures of various sizes and structures. The process is simple and highly operable, improving the appearance qualification rate of the product. Attached Figure Description

[0031] Figure 1 This is a schematic diagram showing the specific dimensions and structure of the integrated ceramic green body in Embodiment 1 of the present invention; wherein 1 is the integrated ceramic green body, 2 is the flexible material, and 3 is the fixing adhesive;

[0032] Figure 2 This is a schematic diagram of the cavity filling and cutting points of the integrated ceramic green body in Embodiment 1 of the present invention;

[0033] Figure 3 This is a top view of the cutting point of the integral ceramic green body in Embodiment 1 of the present invention;

[0034] Figure 4 This is a partially enlarged structural diagram of the double-edged cutting tool and its tip in Embodiment 1 of the present invention. Detailed Implementation

[0035] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0036] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0037] Example 1

[0038] A method for preparing a ceramic encapsulation substrate includes the following steps:

[0039] (1) Take a one-piece ceramic green body, the one-piece ceramic green body having asymmetrical cavities on the front and back sides, the internal volume of the cavity on the back side being smaller than the internal volume of the cavity on the front side, and place the one-piece ceramic green body with the back side facing down on a horizontal platform; the specific dimensions and structural schematic diagram of the one-piece ceramic green body are shown in the figure below. Figure 1 As shown;

[0040] (2) The back cavity is filled with silicone with a Shore hardness of 5, and the shape of the silicone filling is consistent with the size ratio of the internal shape of the back cavity; the volume of the silicone filling accounts for 95% of the volume of the back cavity.

[0041] (3) Use expanding foam to fix the ceramic green body after filling in step (2) onto the vacuum adsorption platform, confirm the initial cutting line position, and use a double-edged tool to position and cut; the structural diagram of the double-edged tool is shown in the figure. Figure 4 As shown;

[0042] The double-edged knife includes a double-angled blade tip and a parallel blade body fixedly connected to the double-angled blade tip. The double-angled blade tip includes a blade tip A as the tip of the blade tip and a blade tip B near the blade body. The angle between the edge of blade tip A and the vertical direction is a vertical inclination angle A; the angle between the edge of blade tip B and the vertical direction is a vertical inclination angle B; the angle of vertical inclination angle A is 30°; the vertical length of blade tip A is 0.1mm; the angle of vertical inclination angle B is 60°; the vertical length of blade tip B is 0.3mm; and the blade body thickness is 0.2mm.

[0043] The cutting process includes a first stage, a second stage, and a third stage. The first stage involves the A-tip blade contacting the ceramic green body until the B-tip blade contacts the ceramic green body, with a cutting speed a of 1 mm / s. The second stage involves the B-tip blade contacting the ceramic green body until the parallel blade contacts the ceramic green body, with a cutting speed b of 3 mm / s. The third stage involves the parallel blade contacting the ceramic green body until the cutting is complete, with a cutting speed c of 4.5 mm / s. A schematic diagram of the cavity filling and cutting point cross-section of the integrated ceramic green body is shown below. Figure 2 As shown, the top view of the cutting site is as follows: Figure 3 As shown;

[0044] (4) After cutting, the ceramic green body is placed at 150°C for 15 minutes to remove the foaming adhesive. Then the silicone is peeled off and removed to obtain a single ceramic encapsulation base green body.

[0045] The preparation methods of the ceramic encapsulation bases in Examples 1-14 and Comparative Examples 1-10 are basically the same as those in Example 1, with the differences shown in Table 1.

[0046] Table 1. Preparation parameters of Examples 1-14 and Comparative Examples 1-10

[0047]

[0048]

[0049] The preparation method of Comparative Example 11 is substantially the same as that of Example 1, and the main difference lies in that in step (3), the cutting speeds of the three stages are different, specifically, a>b<c, that is, the cutting speed a of the first stage is 4mm / s, the cutting speed b of the second stage is 3mm / s, and the cutting speed c of the third stage is 4.5mm / s.

[0050] The preparation method of Comparative Example 12 is substantially the same as that of Example 1, and the main difference lies in that in step (3), the cutting speeds of the three stages are different, specifically, a c means that the cutting speed a in the first stage is 1 mm / s, the cutting speed b in the second stage is 3 mm / s, and the cutting speed c in the third stage is 2 mm / s.

[0051] The preparation method of Comparative Example 13 is basically the same as that of Example 1. The main difference is that the cutting speeds of the three stages in step (3) are different. Specifically, a>b>c, that is, the cutting speed a in the first stage is 4mm / s, the cutting speed b in the second stage is 3mm / s, and the cutting speed c in the third stage is 2mm / s.

[0052] The single ceramic encapsulation base green blanks prepared in the examples and comparative examples were tested. The test contents and standards are shown in Table 2, and the test results are shown in Table 3.

[0053] Table 2 Summary of Test Content and Standards

[0054]

[0055] Table 3. Test results of green blanks from the examples and comparative examples.

[0056]

[0057]

[0058] As can be seen from the test results in Table 3, the ceramic green bodies of Examples 1-14 have better precision and appearance pass rate than those of Comparative Examples 1-13. In Comparative Examples 1 and 2, the poor hardness of the flexible material led to a decrease in both the appearance and precision of the green bodies. In Comparative Examples 3 and 4, the insufficient filling amount of the flexible material resulted in poor buffering effect during cutting, leading to a reduction in the precision or appearance of the green bodies. In Comparative Examples 5-8, the blade tip angle and vertical length were inadequate, making it impossible to obtain green bodies with high precision and appearance pass rate. In Comparative Example 9, the use of hard stainless steel as filler was less effective than that of flexible material. In Comparative Example 10, no filler material was added, resulting in severe deformation of the green body structure after cutting, and even the detachment of the conductive patterns printed on the surface. In Comparative Examples 11-13, poor cutting speed control resulted in the green body's precision failing to meet the standard.

[0059] 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 method for preparing a ceramic encapsulation substrate, characterized in that, Includes the following steps: (1) Take an integral ceramic green body, the front and back of the integral ceramic green body have cavities with asymmetrical structures, the internal volume of the back cavity is smaller than the internal volume of the front cavity, and place the integral ceramic green body with the back side facing down. (2) The back cavity is filled with a flexible material; (3) Fix the ceramic green body after filling in step (2) with adhesive, confirm the initial cutting line position, and cut after positioning with a double-edged tool; the double-edged tool includes a double-angled tip and a blade body fixedly connected to the double-angled tip, the double-angled tip includes a tip A as the tip top and a tip B near the blade body, the angle between the edge of tip A and the vertical direction is a vertical tilt angle A; the angle between the edge of tip B and the vertical direction is a vertical tilt angle B; the vertical tilt angle A is smaller than the vertical tilt angle B; The cutting process includes a first stage, a second stage, and a third stage; the first stage is from the contact between the blade tip A and the ceramic green body until the contact between the blade tip B and the ceramic green body; the second stage is from the contact between the blade tip B and the ceramic green body until the parallel blade body contacts the ceramic green body; the third stage is from the contact between the parallel blade body and the ceramic green body until the cutting is completed. (4) Remove the fixing adhesive and take out the flexible material to obtain a single ceramic encapsulation base green blank; In step (2), the filling volume of the flexible material accounts for 92% to 98% of the volume of the back cavity; In step (2), the Shore hardness of the flexible material is 5 to 30 degrees. In step (3), the vertical tilt angle of the blade tip A is 20°~45°, and the vertical length of the blade tip A is 0.02mm~0.25mm; the vertical tilt angle of the blade tip B is 45°~70°; and the vertical length of the blade tip B is 0.1mm~0.5mm. In step (3), the cutting speed of the first stage is less than the cutting speed of the second stage and less than the cutting speed of the third stage.

2. The method for preparing the ceramic encapsulation substrate according to claim 1, characterized in that, In step (2), the volume of the flexible material accounts for 94% to 96% of the volume of the back cavity.

3. The method for preparing the ceramic encapsulation substrate according to claim 1, characterized in that, In step (2), the Shore hardness of the flexible material is 10 to 20 degrees.

4. The method for preparing the ceramic encapsulation substrate according to claim 1, characterized in that, In step (2), the flexible material includes at least one of flexible silicone, flexible resin, and flexible hydrogel.

5. The method for preparing the ceramic encapsulation substrate according to claim 1, characterized in that, In step (3), the vertical tilt angle A is 25°~40°, and the vertical length of the blade tip A is 0.05mm~0.15mm; the vertical tilt angle B is 50°~65°, and the vertical length of the blade tip B is 0.25mm~0.35mm.

6. The method for preparing the ceramic encapsulation substrate according to claim 1, characterized in that, In step (3), the cutting speed in the first stage is 0.67 mm / s to 2 mm / s, the cutting speed in the second stage is 2.5 mm / s to 3.5 mm / s, and the cutting speed in the third stage is 4 mm / s to 6.5 mm / s.

Images