Chip plastic packaging method based on forevacuum cavity injection molding and chip

Abstract

The invention discloses a chip plastic packaging method based on forevacuum cavity injection molding. The method comprises the steps that a large-size chip to be subjected to plastic packaging is flatly laid on a substrate in a cavity of a lower mold box, and the back surface of the large-size chip is directly placed on the substrate for substrate adsorption; covering the upper mold box on the lower mold box to form a plastic package cavity, and dividing the plastic package cavity into an upper cavity and a lower cavity according to the substrate; filling a gap between the inner wall of the lower cavity and the large-size chip with resin; a large-size chip is subjected to primary injection molding through an injection molding hole formed in the upper mold box; the upper cavity is vacuumized; carrying out secondary injection molding on the large-size chip through the injection molding hole; and opening the upper mold box and stripping the large-size chip from the plastic package cavity to obtain the large-size chip after plastic package. According to the method, the vacuumizing process is more stable, the problems caused by non-uniform vacuum force are reduced, the stability of the production process is improved, and the rate of defective products is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor processing, and in particular to a chip encapsulation method based on pre-vacuum cavity injection molding and a chip. Background Art

[0002] In the semiconductor packaging industry, automatic plastic sealing technology is widely used due to its high efficiency and precision. An important feature of this technology is to evacuate the mold cavity before injection molding to remove air and prevent defects such as bubbles in the plastic package. However, there are technical challenges in processing packaging products such as large-size chips. The chip size of such products is relatively large and occupies most of the area of ​​the packaged product. When using conventional vacuum injection molding methods, due to the large size of the chip and the limitations of the mold cavity, the vacuum force is mainly concentrated on the surface of the chip instead of being evenly distributed on the substrate, which causes the middle part of the substrate to bulge due to vacuum suction, which in turn makes the welding wire touch the upper cavity mold during the formation process, and ultimately causes the problem of poor wire collapse during the packaging process of large-size chips. Summary of the invention

[0003] The embodiment of the present invention provides a chip encapsulation method and a chip based on pre-vacuum cavity injection molding, aiming to solve the problem of poor line collapse in the packaging process of large-size chips existing in the prior art methods.

[0004] In the first aspect, an embodiment of the present invention discloses a chip encapsulation method based on pre-vacuum cavity injection molding, the method comprising: laying a large-size chip to be encapsulated on a substrate in a lower mold box cavity and placing the back surface of the large-size chip directly on the substrate for substrate adsorption; closing an upper mold box cover on the lower mold box to form an encapsulation cavity, and dividing the encapsulation cavity into an upper cavity and a lower cavity according to the substrate; filling a gap between the inner wall of the lower cavity and the large-size chip with resin; performing a primary injection molding on the large-size chip through an injection hole provided in the upper mold box; evacuating the upper cavity; performing a secondary injection molding on the large-size chip through the injection hole; opening the upper mold box and peeling the large-size chip off the encapsulation cavity to obtain the encapsulated large-size chip.

[0005] Furthermore, before the large-size chip to be encapsulated is laid flat on the substrate in the lower mold box cavity and the back surface of the large-size chip is directly placed on the substrate for substrate adsorption, the method also includes immersing the large-size chip to be encapsulated in a wetting agent for rinsing, and the wetting agent is prepared by a solvent, an acid, a surfactant and water in a mass ratio of 2:1:3:4; the large-size chip after rinsing is pre-cut so that the large-size chip meets the preset marking size.

[0006] Furthermore, epoxy molding compound and curing agent are used for molding in one injection molding, and the mass ratio of epoxy molding compound to curing agent is 10:3.

[0007] Furthermore, the secondary injection molding uses polyimide material for plastic sealing.

[0008] Further, the upper cavity is evacuated, including using a vacuum gauge to monitor the vacuum degree inside the upper cavity to ensure that a predetermined vacuum degree standard value is reached; if the vacuum degree inside the upper cavity reaches the predetermined vacuum degree standard value, a static state is maintained to ensure that the resin fully fills the gaps around the large-size chip and discharges bubbles.

[0009] Furthermore, before the large-size chip to be encapsulated is laid flat on the substrate in the lower mold box cavity and the back surface of the large-size chip is directly placed on the substrate for substrate adsorption, the method also includes sticking the large-size chip to one side surface of the substrate, and both sides of the substrate are sticky.

[0010] Furthermore, opening the upper mold box and peeling the large-size chip off the plastic packaging cavity to obtain the encapsulated large-size chip includes extending a probe of a chip stripping machine into a gap between the large-size chip and the substrate and applying uniform stress toward the other side surface of the large-size chip to separate the large-size chip from the substrate.

[0011] Furthermore, the substrate is made of glass fiber reinforced epoxy resin material.

[0012] Furthermore, after opening the upper mold box and peeling the large-size chip from the plastic encapsulation cavity to obtain the plastic-encapsulated large-size chip, the method also includes setting an expected chip thickness value, and judging whether the thickness of the large-size chip meets the standard for stopping plastic encapsulation according to the expected chip thickness value; if the thickness of the large-size chip meets the standard for stopping plastic encapsulation, stopping plastic encapsulation and emptying the plastic encapsulation cavity.

[0013] In a second aspect, an embodiment of the present invention further discloses a chip, wherein a large-size chip is prepared by encapsulating a large-size chip to be encapsulated using the chip encapsulation method based on pre-vacuum cavity injection molding as described above.

[0014] The above-mentioned scheme embodiment ensures the flatness of the substrate during the packaging process by adjusting the order of injection molding and vacuuming, reduces the problem of wire collapse caused by the arching of the substrate, and thus improves the overall quality of the packaged product. The improved process makes the vacuuming process smoother, reduces the problems caused by uneven vacuum force, improves the stability of the production process, and reduces the defective product rate. Keeping the wire arc from being bent or exceeding the standard effectively avoids the risk of short circuit caused by wire arc problems, and improves the electrical performance and reliability of the product. By controlling the injection molding time segmentation and starting vacuuming in the middle of the injection molding process, the flow and solidification of the injection molding material can be better controlled, and the accuracy and repeatability of the injection molding process can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0016] Figure 1 A schematic flow chart of a chip encapsulation method based on pre-vacuum cavity injection molding provided in an embodiment of the present invention;

[0017] Figure 2 A schematic diagram of the structure inside the plastic packaging cavity provided by an embodiment of the present invention;

[0018] Figure 3 Another schematic diagram of the structure in the plastic packaging cavity provided by an embodiment of the present invention.

[0019] Figure Number:

[0020] 1. Large size chip; 2. Upper mold box; 3. Lower mold box; 4. Substrate; 5. Upper cavity; 6. Lower cavity; 8. Resin filling layer. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0023] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0024] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0025] like Figures 1 to 3 As shown, Figure 1 The method flow chart of the chip encapsulation method based on pre-vacuum cavity injection molding is shown in FIG. The chip encapsulation method based on pre-vacuum cavity injection molding provided in this embodiment includes steps S110 to S170.

[0026] S110 , laying the large-size chip 1 to be plastic-sealed flat on the substrate 4 in the cavity of the lower mold box 3 and placing the back surface of the large-size chip 1 directly on the substrate 4 to adsorb the substrate 4 .

[0027] S120 , covering the upper mold box 2 with the lower mold box 3 to form a plastic sealing cavity, and dividing the plastic sealing cavity into an upper cavity 5 and a lower cavity 6 according to the substrate 4 .

[0028] S130 , filling the gap between the inner wall of the lower cavity 6 and the large-size chip 1 with resin.

[0029] S140 , performing a first injection molding on the large-size chip 1 through the injection molding hole provided in the upper mold box 2 .

[0030] S150, evacuating the upper cavity 5.

[0031] S160, performing secondary injection molding on the large-size chip 1 through the injection hole.

[0032] S170 , opening the upper mold box 2 and peeling the large-size chip 1 off the plastic packaging cavity to obtain the plastic-packaged large-size chip 1 .

[0033] In actual use scenarios, in the field of semiconductor packaging, in the field of semiconductor packaging, especially when using automatic plastic packaging technology to process large-size chips 1, the packaging quality and efficiency are affected: when the chip size is large and occupies most of the space in the cavity, the point of action of the vacuum force is mainly concentrated on the surface of the chip. Since the area of ​​the chip is much larger than that of the substrate 4, the distribution of the vacuum force on the chip is much more uniform than on the substrate 4, resulting in a smaller vacuum force on the substrate 4. This uneven force distribution causes the middle part of the substrate 4 to be subjected to an upward force, while the edge part cannot move upward in the same way due to the constraint of the mold, resulting in a bulge in the middle part of the substrate 4. Due to the limited cavity space, the distance between the chip and the cavity wall is small, and the air flow is limited, which will affect the vacuum effect. During the vacuum process, it is difficult to quickly discharge the air in the cavity, resulting in insufficient vacuum, which further exacerbates the bulge in the middle part of the substrate 4. The substrate 4 material usually has a certain degree of flexibility and is prone to deformation when subjected to uneven forces. The thickness of the substrate 4 and the elastic modulus of the material will also affect its degree of deformation under the action of the vacuum force. Since the middle part of the substrate 4 is raised, the height of the arc of the welding wire may be reduced, increasing the risk of contact with the upper cavity 5 mold. The arc of the welding wire contacting the mold will cause the arc to deform or even break, resulting in poor wire collapse. In the packaging of large-size chips 1, the layout and shape design of the welding wires are particularly important. If the welding wire design is unreasonable, problems are more likely to occur when the substrate 4 is raised. If the design of the upper cavity 5 mold does not take into account the characteristics of the large-size chip 1, the distance between the mold and the welding wire may be too small, increasing the risk of contact. The raised substrate 4 may cause changes in the flow path of the packaging material, affecting the filling effect of the packaging material, thereby generating voids or bubbles. The raised substrate 4 may cause uneven stress distribution inside the package body, affecting the long-term reliability of the package.

[0034] The embodiment of this scheme can effectively solve the problems encountered by large-size chips 1 during the automatic plastic packaging process. The large-size chip 1 is laid flat on the substrate 4 in the cavity of the lower mold box 3, and the chip is directly placed on the substrate 4 with its back surface facing away for substrate 4 adsorption. This step is the basis of the plastic packaging process, ensuring that the chip is correctly placed and fixed on the substrate 4, and preparing for subsequent steps. The upper mold box 2 is covered on the lower mold box 3 to form a plastic packaging cavity, which is divided into an upper cavity 5 and a lower cavity 6. This step creates a closed space required for plastic packaging, preparing for resin filling and injection molding. The gap between the inner wall of the lower cavity 6 and the chip is filled with resin. This step helps to reduce the air trapped between the chip and the cavity, prepares for one-time injection molding, and also helps to improve the structural integrity of the plastic packaging body. The chip is injected once through the injection hole of the upper mold box 2. The purpose of one injection molding is to preliminarily fix the chip and lay the foundation for subsequent vacuuming and secondary injection molding. By vacuuming the upper cavity 5, the problem of bulging in the middle part of the substrate 4 can be effectively reduced, because the chip has been partially fixed by the resin injection molding at this time. The chip is subjected to secondary injection molding through the injection hole. The secondary injection molding further fills the cavity to ensure the integrity of the plastic package and the complete fixation of the chip. Open the upper mold box 2 and peel the plastic-encapsulated chip from the plastic package cavity. The plastic encapsulation process is completed to obtain the final product. The peeling process requires careful operation to avoid damage to the chip or the plastic package. Through the method of primary injection molding and secondary injection molding, the chip is gradually fixed to reduce the deformation of the substrate 4. The upper cavity 5 is vacuumed before the secondary injection molding to reduce the risk of bulging in the middle part of the substrate 4. Filling the lower cavity 6 with resin helps to improve the uniformity and structural strength of the plastic package.

[0035] In summary, for the problems encountered by the large-size chip 1 during the automatic plastic encapsulation process, by first performing resin filling and then performing step-by-step injection molding, the chip can be gradually fixed and the deformation of the substrate 4 caused by uneven vacuum force can be reduced. After one injection molding, the chip has been partially fixed, which helps to reduce the phenomenon of bulging in the middle part of the substrate 4 when vacuuming. Vacuuming the upper cavity 5 before the secondary injection molding can ensure that there is almost no air inside the cavity during the flow of the injection molding material, thereby avoiding the generation of bubbles in the plastic encapsulation body. By vacuuming the upper cavity 5, the bulge in the middle part of the substrate 4 caused by the uneven action of the vacuum force is reduced, and the poor collapse line caused by the arc of the welding wire contacting the upper cavity 5 mold is avoided. Filling the gap between the inner wall of the lower cavity 6 and the chip with resin to form a resin filling layer 8 can ensure that the air between the chip and the substrate 4 is effectively removed. Resin filling helps to improve the compactness of the plastic encapsulation, reduce the bubble problem caused by trapped air, and also provides a certain support for the chip, reducing the risk of deformation of the substrate 4. By pre-fixing the chip by one injection molding, the force on the substrate 4 is more uniform during the subsequent vacuuming process, thereby reducing the phenomenon of the bulge in the middle part of the substrate 4. By filling with resin, the gap between the chip and the cavity wall is reduced, the air flow is improved, the vacuuming process is more effective, and the bubble problem caused by trapped air is reduced. Since the deformation of the substrate 4 is reduced, the arc of the welding wire will not contact the upper cavity 5 mold, thereby avoiding the problem of poor wire collapse and improving the quality and reliability of the welding wire. By adjusting the order of injection molding and vacuuming, the flatness of the substrate 4 during the packaging process is ensured, and the problem of poor wire collapse caused by the arch of the substrate 4 is reduced, thereby improving the overall quality of the packaged product. The improved process makes the vacuuming process smoother, reduces the problems caused by uneven vacuum force, improves the stability of the production process, and reduces the defective product rate. Keeping the arc from being bent or exceeding the standard effectively avoids the risk of short circuit caused by the arc problem, and improves the electrical performance and reliability of the product. By controlling the injection molding time segmentation and starting vacuuming in the middle of the injection molding, the flow and solidification of the injection molding material can be better controlled, and the accuracy and repeatability of the injection molding process are improved. The improved solution reduces rework and scrap caused by the arching of the substrate 4 and the problem of welding wires, improves production efficiency and reduces production costs. This solution is suitable for the packaging of large-size chips 1, especially for products with a relatively high chip area, and can effectively solve the problems in traditional packaging processes. The improvement measures can be adjusted on existing automatic plastic packaging equipment without the need for large-scale equipment replacement, and are easy to implement and promote. In summary, this solution not only improves the quality and production efficiency of packaged products, but also reduces production costs, providing a more efficient and reliable solution for the field of semiconductor packaging.

[0036] Furthermore, before the large-size chip 1 to be encapsulated is laid flat on the substrate 4 in the cavity of the lower mold box 3 and the back surface of the large-size chip 1 is directly placed on the substrate 4 for substrate 4 adsorption, the method also includes immersing the large-size chip 1 to be encapsulated in a wetting agent for rinsing, and the wetting agent is prepared by a solvent, an acid, a surfactant and water in a mass ratio of 2:1:3:4; the large-size chip 1 after rinsing is pre-cut so that the large-size chip 1 meets the preset marking size.

[0037] Specifically, in order to ensure the cleanliness and dimensional accuracy of the large-size chip 1 before plastic encapsulation, improve the adhesion between the chip and the resin, avoid delamination and falling off, and reduce packaging problems caused by inconsistent chip sizes, before placing the large-size chip 1 on the substrate 4, it is immersed in a proportionally configured wetting agent for rinsing. The ingredients of the wetting agent include solvent, acid, surfactant and water, and this mixture can effectively remove grease, dust and other pollutants on the surface of the chip. The rinsing process can ensure that the chip surface is clean, thereby improving the adhesion between the plastic encapsulation material and the chip, and reducing the possibility of bubbles and delamination in the plastic encapsulation body. The large-size chip 1 after rinsing is pre-cut to ensure that the size of each chip meets the preset marking size. Through precise cutting, the correct placement of the chip on the substrate 4 can be ensured, and packaging problems caused by inconsistent sizes, such as uneven encapsulation, overflowing glue or welding wire problems, can be avoided. Solvent, acid, surfactant and water are configured in a mass ratio of 2:1:3:4 to prepare a wetting agent. The large-size chip 1 to be encapsulated is immersed in the wetting agent and fully rinsed to ensure that the surface is clean. After rinsing, the chip is removed from the infiltrant and dried to remove excess infiltrant. The dried chip is cut using precision cutting equipment according to the preset marking size. The pre-cut and dried large-sized chip 1 is laid flat on the substrate 4 in the cavity of the lower mold box 3, ensuring that the back surface of the chip is directly placed on the substrate 4 for substrate 4 adsorption. These steps not only solve the technical difficulties of large-sized chips 1 in the automatic plastic packaging process, but also improve the overall quality and reliability of the product through rinsing and precise cutting.

[0038] Furthermore, epoxy molding compound and curing agent are used for molding in one injection molding, and the mass ratio of epoxy molding compound to curing agent is 10:3.

[0039] Furthermore, the secondary injection molding uses polyimide material for plastic sealing.

[0040] Furthermore, the upper cavity 5 is evacuated, including using a vacuum gauge to monitor the vacuum degree inside the upper cavity 5 to ensure that a predetermined vacuum degree standard value is reached; if the vacuum degree inside the upper cavity 5 reaches a predetermined vacuum degree standard value, a static state is maintained to ensure that the resin fully fills the gap around the large-size chip 1 and discharges bubbles.

[0041] Specifically, the material selection for the primary injection molding and the secondary injection molding and the vacuuming process are specified in detail. The following is a detailed explanation of these steps and their role in the plastic encapsulation process: Epoxy molding compound is a commonly used semiconductor packaging material, which is widely used due to its good electrical insulation, chemical stability and mechanical strength. The curing agent is used to react with the epoxy molding compound to harden it into a solid state. The mass ratio is 10:3, which is optimized to ensure that the molding compound has good performance after curing. Polyimide is a high-performance polymer with excellent heat resistance, chemical resistance and mechanical properties. The use of polyimide material in the secondary injection molding can provide an additional protective layer and enhance the overall performance of the package, especially under high temperature or harsh environment. During the vacuuming process, the vacuum degree inside the upper cavity 5 can be monitored in real time using a vacuum gauge to ensure that the predetermined vacuum degree standard value is reached. This step is crucial to ensure the quality of plastic encapsulation, because the appropriate vacuum degree can effectively remove air and bubbles in the cavity and prevent defects in the plastic encapsulation. When the vacuum degree inside the upper cavity 5 reaches the predetermined standard value, keep it still for a period of time to ensure that the resin fully fills the gap around the large-size chip 1 and discharges any bubbles that may exist. This process helps the resin flow and penetrate better, thereby improving the density and uniformity of the plastic package. Mix the epoxy molding compound and the curing agent according to the ratio. Inject the mixed molding compound into the lower cavity 6 through the injection hole to cover the large-size chip 1. After the first injection molding is completed, vacuum operation is performed. When the vacuum degree reaches the predetermined standard and remains still, polyimide material is used for secondary injection molding. Before secondary injection molding, a vacuum gauge is used to monitor the vacuum degree of the upper cavity 5. After reaching the predetermined vacuum degree, keep it still to ensure that the resin is filled and the bubbles are discharged. Through these meticulous steps, the problems encountered by the large-size chip 1 in the plastic packaging process can be effectively solved, and the quality and reliability of the package can be improved. In actual operation, these steps may need to be further optimized through experiments to ensure optimal production efficiency and product performance.

[0042] Furthermore, before the large-size chip 1 to be encapsulated is laid flat on the substrate 4 in the cavity of the lower mold box 3 and the back surface of the large-size chip 1 is directly placed on the substrate 4 for substrate 4 adsorption, the method also includes pasting the large-size chip 1 to one side surface of the substrate 4, and both side surfaces of the substrate 4 are sticky.

[0043] Furthermore, opening the upper mold box 2 and peeling the large-size chip 1 off the plastic packaging cavity to obtain the encapsulated large-size chip 1 includes extending the probe of the stripping machine into the gap between the large-size chip 1 and the substrate 4 and applying uniform stress toward the other side surface of the large-size chip 1 to separate the large-size chip 1 from the substrate 4.

[0044] Specifically, before placing the large-size chip 1 on the substrate 4, the chip is first pasted on one side surface of the substrate 4. This approach can ensure that the chip is firmly fixed on the substrate 4 during the plastic packaging process to prevent poor packaging caused by movement or tilting. Both sides of the substrate 4 are sticky, which provides double-sided fixation for the chip and increases the stability and reliability of fixation. After the plastic packaging process is completed, the plastic-encapsulated chip needs to be peeled off from the substrate 4. This step is completed by a stripper. The probe of the stripper extends into the gap between the large-size chip 1 and the substrate 4. This is a precise operation, and it is necessary to ensure that the probe does not damage the chip or the substrate 4. The probe applies uniform stress to the other side surface of the large-size chip 1, which is to smoothly separate the chip and the substrate 4 to avoid chip damage caused by uneven stress. Uniform stress can reduce the mechanical stress on the chip during the stripping process and improve the yield of the product. Apply an appropriate amount of adhesive to one side surface of the substrate 4. Paste the back surface of the large-size chip 1 to the substrate 4 to ensure that the chip position is accurate. Plastic packaging is performed according to the steps described above, including primary injection molding, vacuuming, secondary injection molding, etc. After the plastic encapsulation is completed, the device is moved to the position of the stripper. Operate the stripper and accurately insert the probe into the gap between the chip and the substrate 4. Slowly apply uniform stress until the chip is smoothly stripped from the substrate 4. These steps not only ensure the stable fixation of the chip during the plastic encapsulation process, but also provide an efficient and safe chip stripping method, thereby improving the automation and production efficiency of the entire packaging process. In actual applications, these steps may need to be optimized through multiple tests to ensure the best operating effect and product quality.

[0045] Furthermore, the substrate 4 is made of glass fiber reinforced epoxy resin material.

[0046] Furthermore, after opening the upper mold box 2 and peeling the large-size chip 1 from the plastic encapsulation cavity to obtain the plastic-encapsulated large-size chip 1, the method also includes setting an expected chip thickness value, and judging whether the thickness of the large-size chip 1 meets the standard for stopping plastic encapsulation according to the expected chip thickness value; if the thickness of the large-size chip 1 meets the standard for stopping plastic encapsulation, stopping plastic encapsulation and emptying the plastic encapsulation cavity.

[0047] Specifically, the selection of the substrate 4 material and the control of the chip thickness after plastic encapsulation can be specified in detail in the process flow. The following is a detailed explanation of these steps and their role in the plastic encapsulation process. The glass fiber reinforced epoxy resin material has good mechanical strength, heat resistance and electrical insulation, and is suitable for use as the substrate 4 material for semiconductor packaging. The selection of this material helps to improve the stability of the substrate 4, can better support the large-size chip 1 during the plastic encapsulation process, and resist the stress caused by vacuuming and injection molding. During the plastic encapsulation process, an expected chip thickness value is set as a quality control standard. This value is based on the product design requirements to ensure that the chip after plastic encapsulation meets a specific thickness specification. After the plastic encapsulation is completed, the actual thickness of the large-size chip 1 is detected by a measuring device (such as a thickness gauge). If the actual thickness meets the preset stop plastic encapsulation standard, it means that the plastic encapsulation process is successful and the operation can be stopped. Once the chip thickness meets the standard, the plastic encapsulation operation is stopped to avoid excessive plastic encapsulation causing the chip to be too thick or deformed. The plastic encapsulation cavity is emptied to prepare for the next plastic encapsulation process to ensure that there is no residual resin or other substances in the cavity. The substrate 4 is prepared using a glass fiber reinforced epoxy resin material, and the surface of the substrate 4 is ensured to be flat and clean. Plastic encapsulation is performed according to the established steps, including chip pasting, injection molding, vacuuming, etc. After the plastic encapsulation is completed, a measuring device is used to detect the chip thickness and compare the actual thickness with the expected thickness value. If the chip thickness meets the standard, the plastic encapsulation equipment is turned off and the operation of emptying the plastic encapsulation cavity is performed. If the chip thickness does not meet the standard, the plastic encapsulation parameters are adjusted and the plastic encapsulation is performed again. Through these steps, not only the stability and reliability of the substrate 4 during the plastic encapsulation process are ensured, but also the quality of the final product is guaranteed by accurately controlling the chip thickness. In actual production, these control measures help to improve the degree of automation, reduce human errors, and improve production efficiency and product consistency.

[0048] In the second aspect, the present case discloses a chip, wherein a large-size chip 1 is prepared by encapsulating a large-size chip 1 to be encapsulated using the chip encapsulation method based on pre-vacuum cavity injection molding as described above.

[0049] The present invention discloses a chip encapsulation method based on pre-vacuum cavity injection molding and a chip prepared by the method, the method comprising: laying a large-size chip 1 to be encapsulated on a substrate 4 in a cavity of a lower mold box 3 and placing the back surface of the large-size chip 1 directly on the substrate 4 to adsorb the substrate 4; covering an upper mold box 2 on the lower mold box 3 to form an encapsulation cavity, and dividing the encapsulation cavity into an upper cavity 5 and a lower cavity 6 according to the substrate 4; filling the gap between the inner wall of the lower cavity 6 and the large-size chip 1 with resin; performing a primary injection molding on the large-size chip 1 through an injection hole provided in the upper mold box 2; evacuating the upper cavity 5; performing a secondary injection molding on the large-size chip 1 through the injection hole; opening the upper mold box 2 and peeling the large-size chip 1 off the encapsulation cavity to obtain the encapsulated large-size chip 1. The above scheme effectively solves the problems encountered by large-size chips 1 in the automatic plastic packaging process through innovative step-by-step injection molding and pre-vacuum cavity injection molding technology, improves the packaging quality and production efficiency, and optimizes the plastic packaging process to make the entire process more automated and controllable, reducing the impact of human factors and improving the stability of the process.

[0050] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A chip encapsulation method based on pre-vacuum cavity injection molding, characterized in that: The following steps are involved: Laying the large-size chip to be plastic-sealed flat on the substrate in the lower mold box cavity and placing the back surface of the large-size chip directly on the substrate for substrate adsorption; The upper mold box is covered with the lower mold box to form a plastic sealing cavity, and the plastic sealing cavity is divided into an upper cavity and a lower cavity according to the substrate; Filling the gap between the inner wall of the lower cavity and the large-size chip with resin; Performing one-time injection molding on the large-size chip through an injection hole provided in the upper mold box; The upper cavity is evacuated; Performing secondary injection molding on the large-size chip through the injection hole; The upper mold box is opened and the large-size chip is peeled off from the plastic packaging cavity to obtain the plastic-sealed large-size chip.

2. The chip encapsulation method based on pre-vacuum cavity injection molding according to claim 1, characterized in that: Before laying the large-size chip to be encapsulated flat on the substrate in the lower mold box cavity and placing the back surface of the large-size chip directly on the substrate for substrate adsorption, the method further includes: Immersing the large-size chip to be encapsulated in an impregnating agent for rinsing, wherein the impregnating agent is prepared by using a solvent, an acid, a surfactant and water in a mass ratio of 2:1:3:4; The rinsed large-size chip is pre-cut to make the large-size chip conform to a preset marking size.

3. The chip encapsulation method based on pre-vacuum cavity injection molding according to claim 1, characterized in that: The one-time injection molding uses epoxy molding compound and curing agent for molding, and the mass ratio of the epoxy molding compound to the curing agent is 10:

3.

4. The chip encapsulation method based on pre-vacuum cavity injection molding according to claim 1, characterized in that: The secondary injection molding uses polyimide material for plastic sealing.

5. The chip encapsulation method based on pre-vacuum cavity injection molding according to claim 1, characterized in that: The step of evacuating the upper cavity comprises: Using a vacuum gauge to monitor the vacuum inside the upper cavity to ensure that a predetermined vacuum standard value is reached; If the vacuum degree inside the upper cavity reaches a predetermined vacuum degree standard value, the static state is maintained to ensure that the resin fully fills the gap around the large-size chip and exhausts bubbles.

6. The chip encapsulation method based on pre-vacuum cavity injection molding according to claim 3, characterized in that: Before laying the large-size chip to be encapsulated flat on the substrate in the lower mold box cavity and placing the back surface of the large-size chip directly on the substrate for substrate adsorption, the method further includes: The large-size chip is pasted on one side surface of the substrate, and both sides of the substrate are sticky.

7. The chip encapsulation method based on pre-vacuum cavity injection molding according to claim 6, characterized in that: The step of opening the upper mold box and peeling the large-size chip from the plastic packaging cavity to obtain the plastic-sealed large-size chip comprises: The probe of the chip stripping machine is extended into the gap between the substrate and the lower mold box and uniform stress is applied toward the other side surface of the large-size chip to separate the substrate and the large-size chip from the lower mold box.

8. The chip encapsulation method based on pre-vacuum cavity injection molding according to claim 6, characterized in that: The base plate is made of glass fiber reinforced epoxy resin material.

9. The chip encapsulation method based on pre-vacuum cavity injection molding according to claim 5, characterized in that: After the upper mold box is opened and the large-size chip is peeled off from the plastic packaging cavity to obtain the plastic-sealed large-size chip, the method further includes: Setting an expected chip thickness value, and judging whether the thickness of the large-size chip meets the standard for stopping plastic packaging according to the expected chip thickness value; If the thickness of the large-size chip meets the standard for stopping plastic encapsulation, the plastic encapsulation is stopped and the plastic encapsulation cavity is emptied.

10. A chip, characterized in that: The chip is prepared by encapsulating a large-size chip to be encapsulated using the chip encapsulation method based on pre-vacuum cavity injection molding as described in any one of claims 1 to 9.

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