Package structure

Abstract

The utility model discloses a packaging structure. The packaging structure comprises a lead frame, a first chip, a separator and a second chip which are stacked. The lead frame, the first chip and the separator are bent in the direction facing or away from the second chip, so that the surface, facing the bonding piece, of the separator forms a first curved surface; the packaging structure further comprises a bonding piece located between the second chip and the partition piece, the second chip is bonded to the partition piece through the bonding piece, the bonding piece is made of elastic materials, the surface, facing the partition piece, of the bonding piece forms a second curved surface attached to the first curved surface, and the surface, away from the partition piece, of the bonding piece forms a plane, or the bonding piece is made of elastic materials. A third curved surface is formed on the surface, far away from the separator, of the bonding piece, and the curvature of the third curved surface is smaller than that of the second curved surface. According to the utility model, the bonding piece can absorb the buckling deformation of the separator through the deformation of the bonding piece, so that the layering problem can be effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor device technology, and in particular to a packaging structure. Background Technology

[0002] For packaging structures with multiple chips, the common practice is to place the chips side by side on the substrate. However, this method increases the area of ​​the packaging structure. Therefore, there is another type of packaging structure that reduces the area by stacking the chips along the height direction. Specifically, the bottom chip is connected to the substrate by means of reflow soldering, and then the upper chip is stacked on the bottom chip. However, due to the difference in thermal expansion coefficients between the bottom chip and the substrate, when the bottom chip is connected to the substrate, the whole structure will warp and deform after being heated at high temperature. This causes the upper chip to not fit well with the lower structure when stacked, which in turn leads to delamination problems in subsequent processes. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a packaging structure that enables good bonding between the upper chip and the lower structure, thus improving the delamination problem.

[0004] The packaging structure according to the first embodiment of this utility model includes:

[0005] Lead frame;

[0006] The first chip is disposed on one side of the lead frame;

[0007] A separator is disposed on the side of the first chip away from the lead frame;

[0008] The second chip is disposed on the side of the separator away from the first chip;

[0009] The lead frame, the first chip, and the separator are all bent in a direction toward or away from the second chip, so that the surface of the separator facing the second chip forms a first curved surface.

[0010] The packaging structure further includes an adhesive member located between the second chip and the separator. The second chip is bonded to the separator via the adhesive member. The adhesive member is made of an elastic material. The surface of the adhesive member facing the separator forms a second curved surface that fits with the first curved surface. The surface of the adhesive member away from the separator forms a plane. Alternatively, the surface of the adhesive member away from the separator forms a third curved surface, and the curvature of the third curved surface is less than the curvature of the second curved surface.

[0011] The packaging structure according to the first embodiment of this utility model has at least the following beneficial effects:

[0012] In this embodiment, an adhesive is also provided between the second chip and the separator. The adhesive is made of a material that has adhesive ability and can be elastically deformed. In this way, the adhesive serves two purposes: firstly, it acts as an adhesive and fixative, thereby connecting the second chip 200 and the separator; secondly, the adhesive can absorb the warping deformation of the separator through its own deformation, thereby maintaining a good fit with the separator and effectively improving the delamination problem.

[0013] In other embodiments of this utility model, the viscoelastic value of the adhesive is less than or equal to 300 Pa·s.

[0014] In other embodiments of this utility model, the viscoelastic value of the adhesive is greater than or equal to 100 Pa·s.

[0015] In other embodiments of this utility model, the elastic modulus of the adhesive is less than or equal to 600 MPa.

[0016] In other embodiments of this utility model, the elastic modulus of the adhesive is greater than or equal to 100 MPa.

[0017] In other embodiments of this utility model, along the direction from the first chip to the second chip, the distance between the part of the second curved surface closest to the second chip and the part furthest from the second chip is 8μm to 13μm.

[0018] In other embodiments of this utility model, the separator is a metal sheet, the adhesive is made of insulating material, the lead frame includes a first frame and a second frame spaced apart and arranged side by side along a direction parallel to the first chip, the first chip is electrically connected to the first frame, and the separator is electrically connected to the first chip and the second frame respectively.

[0019] In other embodiments of this utility model, the separator includes a main body and a bent portion. The main body is electrically connected to the first chip, and the bent portion is bent relative to the main body toward the lead frame. The bent portion is electrically connected to the second frame.

[0020] In other embodiments of this utility model, the main body portion is provided with a flow hole that extends through the thickness direction of the main body portion in the portion between the bent portion and the first chip.

[0021] In other embodiments of this utility model, the separator is provided with a clearance groove on the side facing the lead frame, the projection of the side of the first chip facing the second frame in the lead frame is defined as the first projection, the projection of the clearance groove in the lead frame is defined as the second projection, and the first projection is located within the second projection.

[0022] Wherein, the first projection and the second projection are spaced apart by a first predetermined distance from the edge of the second frame;

[0023] The packaging structure further includes a second solder paste layer disposed between the first chip and the separator, and the first projection and the second projection are spaced apart by a second predetermined distance from the edge away from the second frame.

[0024] In other embodiments of the present invention, the packaging structure further includes a lead wire, one end of which is electrically connected to the side of the first chip away from the lead wire frame, and the other end of which is electrically connected to the side of the second chip away from the separator. The separator is provided with a clearance hole for avoiding the lead wire, and the clearance hole extends along the length direction of the lead wire.

[0025] In other embodiments of this utility model, the projection of the second chip on the lead frame is defined as the third projection, and the projection of the separator on the lead frame is defined as the fourth projection. The third projection is located within the fourth projection, and the distance between the edge of the third projection and the edge of the corresponding side of the fourth projection is greater than or equal to 100 μm.

[0026] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0028] Figure 1 This is a top view of the packaging structure in an embodiment of the present utility model;

[0029] Figure 2 for Figure 1 A partial schematic diagram of the packaging structure;

[0030] Figure 3 This is a simplified schematic diagram showing the layering relationship of the second chip, adhesive, and separator in an embodiment of the present invention;

[0031] Figure 4 This is a simplified schematic diagram showing the layering relationship of the second chip, adhesive, and separator in another embodiment of the present invention;

[0032] Figure 5 for Figure 1 An exploded view of the mid-package structure;

[0033] Figure 6 for Figure 2 A partial schematic diagram of region A in the middle.

[0034] Figure label:

[0035] First chip 100;

[0036] Second chip 200;

[0037] Lead frame 300, first frame 310, second frame 320;

[0038] Separator 400, first curved surface 401, clearance groove 402, clearance hole 403, flow hole 404, main body 410, bending part 420;

[0039] Adhesive component 500, second curved surface 501, third curved surface 502;

[0040] First solder paste layer 600;

[0041] Second solder paste layer 700;

[0042] First lead 800;

[0043] Second lead 900. Detailed Implementation

[0044] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0045] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0046] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0047] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0048] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] As mentioned earlier, in related technologies, chip stacking schemes can cause warping due to the difference in thermal expansion coefficients between the lower-layer chip and the lead frame, thus affecting the subsequent stacking of upper-layer chips. Based on this, this invention proposes a packaging structure that can absorb warping through the elastic deformation of the adhesive layer, thereby achieving a good fit between the upper-layer chip and the lower-layer structure. The following will provide a detailed description with reference to embodiments and accompanying drawings.

[0050] Reference Figure 1 and Figure 2 The diagram shows a top view and a cross-sectional view of the packaging structure in an embodiment of the present invention, wherein the cutting plane of the cross-sectional view is along... Figure 1 The vertical surface is arranged in the top and bottom direction. As shown in the figure, the package structure includes a first chip 100, a second chip 200, a lead frame 300, and a separator 400. In addition, the package structure also includes a mold body (not shown), which is used to realize the insulation and protection functions. The aforementioned first chip 100, second chip 200, lead frame 300, and separator 400 are all covered in the mold body. It should be noted that the coverage mentioned here includes complete coverage and partial coverage. For example, part of the lead frame 300 is covered in the mold body, and another part is exposed from the mold body. The first chip 100, second chip 200, and separator 400 are completely covered in the mold body.

[0051] The molding body is typically formed by curing epoxy resin and is roughly rectangular. The lead frame 300 is made of a conductive metal material. After encapsulation, a portion of the lead frame 300 protrudes from the molding body to form pins for electrical connection with external electrical devices. This embodiment employs a stacked design for the package structure. The first chip 100 is located on one side of the lead frame 300, the separator 400 is located on the side of the first chip 100 away from the lead frame 300, and the second chip 200 is located on the side of the separator 400 away from the first chip 100. Compared to a scheme where the first chip 100 and the second chip 200 are connected side-by-side to the lead frame 300, this effectively reduces the area occupied by the package structure. For example, using... Figure 2 The orientation of the components is explained as follows: the lead frame 300 is located at the bottom layer, the first chip 100 is located above the lead frame 300, the separator 400 is located above the first chip 100, and the second chip 200 is located above the separator 400. The layers are fixed together by welding or bonding.

[0052] Typically, the manufacturing process of the above-mentioned packaging structure involves first soldering the first chip 100 to the lead frame 300 using processes such as reflow soldering, and then stacking other layers. For example, the packaging structure also includes a first solder paste layer 600 disposed between the first chip 100 and the lead frame 300. The first chip 100 is fixed to the lead frame 300 and electrically connected to the lead frame 300 through the first solder paste layer 600. Because of the difference in the coefficients of thermal expansion of the first chip 100, the lead frame 300, and the solder paste between them, the lower structure consisting of the first chip 100, the lead frame 300, and the first solder paste layer 600 will warp after high-temperature reflow soldering due to inconsistent deformation. If the separator 400 is also soldered to the first chip 100 using reflow soldering or other processes (for example, the package structure also includes a second solder paste layer 700 disposed between the first chip 100 and the separator 400, the separator 400 being fixed to the first chip 100 and electrically connected to the first chip 100 through the second solder paste layer 700), the degree of warping deformation will be further increased. Figure 3 , Figure 4 As shown, it illustrates a simplified schematic diagram after the spacer 400 has warped and deformed. Specifically, in some embodiments, the lead frame 300, the first chip 100, and the spacer 400 are all aligned in the direction toward the second chip 200 (e.g., Figure 3 , Figure 4 The separator 400 is curved in an upward direction, and its upper surface forms an upwardly convex first curved surface 401. In other embodiments, the lead frame 300, the first chip 100, and the separator 400 are all curved in a direction away from the second chip 200 (e.g., in an upward direction). Figure 3 , Figure 4The separator 400 is curved downwards, forming a downwardly recessed first curved surface 401 on its lower surface. If the second chip 200 is connected to the separator 400 using a conventional connecting layer, the connecting layer will not adhere well to the separator 400 due to the first curved surface 401, leading to detachment during subsequent processes.

[0053] To improve the above-mentioned problems, this embodiment further provides an adhesive member 500 between the second chip 200 and the separator 400. The adhesive member 500 is made of a material with adhesive ability and elastic deformation. Thus, the adhesive member 500 serves two purposes: firstly, it provides adhesive fixation, connecting the second chip 200 and the separator 400; secondly, the adhesive member 500 can absorb the warping deformation of the separator 400 through its own deformation, thereby maintaining a good fit with the separator 400 and effectively improving the delamination problem. Specifically, in some specific embodiments, refer to... Figure 3 The adhesive 500 has a second curved surface 501 on its surface facing the separator 400, which adheres to the first curved surface 401. The surface of the adhesive 500 away from the separator 400 is flat. That is, in this embodiment, different surfaces of the adhesive 500 have different shapes. For the side used to adhere to the first curved surface 401, it forms a second curved surface 501 to ensure adhesion with the separator 400. For the side facing the second chip 200, it forms a flat surface to ensure adhesion with the second chip 200. In other embodiments, refer to... Figure 4 The adhesive 500 has a second curved surface 501 on its surface facing the separator 400, which adheres to the first curved surface 401. The adhesive 500 also has a third curved surface 502 on its surface away from the separator 400. The curvature of the third curved surface 502 is less than that of the second curved surface 501; that is, the third curved surface 502 is gentler than the first curved surface 401. In this embodiment, different surfaces of the adhesive 500 have different shapes. For the side that adheres to the first curved surface 401, a second curved surface 501 is formed to ensure adhesion to the separator 400. For the side facing the second chip 200, a third curved surface 502 is formed to ensure adhesion to the second chip 200. It should be noted that... Figure 4 The illustrated embodiments and Figure 3 The difference between the embodiments shown is: Figure 4 In the embodiments, the lower side of the second chip 200 is allowed to have a certain curvature, or the second chip 200 as a whole is allowed to have a certain curvature.

[0054] This embodiment improves the bonding quality between the second chip 200 and the separator 400 by using the aforementioned adhesive 500. It should be noted that warping of the package structure after being heated is a common problem in the semiconductor field. To solve this problem, the industry usually tries to reduce warping, for example by increasing the thickness of the lead frame to increase the strength of the component to resist warping. This utility model adopts another approach, which absorbs the amount of warping by the elastic deformation of the adhesive 500 itself. Even if the lower first chip 100, lead frame 300, separator 400 and other components have a certain degree of warping, it will not affect the stacking of the upper second chip 200.

[0055] Based on the first embodiment, in some embodiments of this utility model, the viscoelastic value of the adhesive 500 is less than or equal to 300 Pa·s. Viscoelasticity represents the ratio of viscous components to elastic components in a material. The lower the viscoelastic value, the higher the viscous component, and the easier the material is to flow and deform. In this embodiment, the viscoelastic value of the adhesive 500 is limited to less than or equal to 300 Pa·s, so that the adhesive 500 is easy to deform, thereby forming a second curved surface 501 that is adapted to it after contacting the first curved surface 401.

[0056] In some specific embodiments, the viscoelastic value of the adhesive 500 is greater than or equal to 100 Pa·s. After the second chip 200 is bonded to the separator 400, the adhesive 500 will be compressed and deformed, causing some of the adhesive 500 to overflow from the periphery of the second chip 200. If the overflow is too large, it may cause quality problems. Based on this, this embodiment limits the viscoelastic value of the adhesive 500 to greater than or equal to 100 Pa·s, so that the adhesive 500 is easy to deform, while ensuring that the overflow after deformation is within the allowable range.

[0057] Based on the first embodiment, in some embodiments of the present invention, the elastic modulus of the adhesive is less than or equal to 600 MPa. The smaller the elastic modulus, the easier the material is to deform. In this embodiment, the elastic modulus of the adhesive 500 is limited to less than or equal to 600 MPa, so that the adhesive 500 is easy to deform, thereby forming a second curved surface 501 that is adapted to it after contacting the first curved surface 401.

[0058] In some specific embodiments, the elastic modulus of the adhesive is greater than or equal to 100 MPa. After the second chip 200 is bonded to the separator 400, the adhesive 500 will be compressed and deformed, causing some of the adhesive 500 to overflow from the periphery of the second chip 200. If the overflow is too large, it may cause quality problems. Based on this, this embodiment limits the elastic modulus of the adhesive 500 to greater than or equal to 100 MPa, so that the adhesive 500 is easy to deform, while ensuring that the overflow after deformation is within the allowable range.

[0059] It should be noted that some packaging structures using stacking solutions in related technologies also mention the method of bonding upper-layer chips through adhesive layers. However, these technologies only mention the bonding function of adhesive layers. They do not specifically address the problem that bonding through adhesive layers may not achieve good adhesion due to the warping of the lower-layer structure, nor do they mention solutions for absorbing warping by utilizing the elastic deformation of adhesive layers, nor do they involve any limitations on the relevant parameters of adhesive layers.

[0060] Based on the first embodiment, in some embodiments of this utility model, along the direction from the first chip 100 to the second chip 200, the distance between the portion of the second curved surface 501 closest to the second chip 200 and the portion furthest from the second chip 200 is 8μm to 13μm. Figure 3 , Figure 4 For example, if the second curved surface 501 is a typical curved surface structure recessed towards the second chip 200, then the part closest to the second chip 200 and the part furthest from the second chip 200 are the center and edge of the surface, respectively, and the distance between them is indicated by L. As mentioned earlier, this embodiment absorbs the warpage of the underlying structure through the deformation of the adhesive 500 itself. Therefore, on the one hand, the adhesive 500 needs to be deformable, and on the other hand, it also needs to have sufficient deformation space. In this embodiment, the maximum deformation on the second curved surface 501 is limited to 8μm to 13μm, which can cover the maximum warpage range of such products. It should be noted that, as mentioned earlier, the related technologies also mention a solution of bonding the upper-layer chip with an adhesive layer. However, they do not specifically address the problem of poor adhesion due to the warping of the lower-layer structure when bonding with an adhesive layer, nor do they mention solutions for absorbing warping by utilizing the elastic deformation of the adhesive layer, nor do they involve limiting the maximum deformation of the adhesive layer. In fact, the adhesive layer in the related technologies only serves an adhesive function, and the surface of the adhesive layer will not undergo relatively large-scale concave or convex deformation. On the other hand, in order to reduce material usage and reduce the thickness of the packaging structure, while meeting the bonding capacity, the thickness of the adhesive layer is usually reduced as much as possible, rather than increased.

[0061] Based on the first embodiment, in some embodiments of this utility model, the separator 400, in addition to its supporting and separating functions, can also function as a conductive element to conduct electricity in the circuit. Specifically, the separator 400 is made of a metallic material; exemplarily, the separator 400 is a metal sheet. (Refer to...) Figure 1 , Figure 5The lead frame 300 includes a first frame 310 and a second frame 320, which are arranged side-by-side and spaced apart along a direction parallel to the first chip 100. The first chip 100 is electrically connected to the first frame 310, and the separator 400 is electrically connected to both the first chip 100 and the second frame 320. For example, the lower surface of the first chip 100 has a drain, and the upper surface has a source and a gate. The drain of the first chip 100 is soldered to the upper surface of the first frame 310 using solder paste. One end of the separator 400 is soldered to the source of the first chip 100 using solder paste, and the other end is soldered to the upper surface of the second frame 320 using solder paste. In related technologies, leads are typically used to connect the chip and the lead frame. However, due to the limited wire diameter, the current carrying capacity is relatively low. This embodiment uses a metal sheet instead of leads to achieve the electrical connection between the first chip 100 and the second frame 320, which increases the current carrying capacity.

[0062] It should be noted that when the separator 400 serves as a conductive connection, in order to prevent a short circuit from occurring between the first chip 100 and the second chip 200, the adhesive 500 is required to have insulating properties. That is, the adhesive 500 in this embodiment is made of a material that simultaneously has adhesiveness, elasticity and insulating ability.

[0063] In some specific embodiments, the separator 400 is made of the same material as the lead frame 300, for example, both are made of copper.

[0064] When the separator 400 is also used for electrical connection between the first chip 100 and the lead frame 300, in some specific embodiments of the present invention, refer to Figure 2 The separator 400 includes a main body 410 and a bent portion 420. The main body 410 is electrically connected to the first chip 100, and the bent portion 420 is bent relative to the main body 410 toward the lead frame 300. The bent portion 420 is electrically connected to the second frame 320. Typically, the lead frame 300 is etched from a sheet of the same thickness. Therefore, the first frame 310 and the second frame 320 have the same maximum thickness, and their upper and lower surfaces remain flush after packaging. Thus, if the separator 400 is set as a flat sheet structure, after the separator 400 is soldered to the first chip 100 with solder paste, there will be a certain distance between the separator 400 and the second frame 320. In this embodiment, by forming a bent portion 420 on the separator 400 that is bent relative to the main body 410, the separator 400 can contact the second frame 320.

[0065] When the separator 400 includes a main body portion 410 and a bent portion 420, in some specific embodiments of the present invention, refer to Figure 1 , Figure 5The portion of the main body 410 between the bent portion 420 and the first chip 100 (referred to as the suspended portion for ease of description) is provided with a flow hole 404 that extends through the thickness direction of the main body 410. As mentioned earlier, due to the lifting effect of the first chip 100 and the related solder paste layer, a gap will be formed on the lower side of the suspended portion of the main body 410. If the flow hole 404 is not provided, when the subsequent molding operation is performed, the molten molding material will enter from both ends of the gap, and the molding material will not be able to completely fill the gap because the gas in the gap cannot be discharged. In this embodiment, by providing the flow hole 404, the path for the molding material to enter the gap is increased, thereby improving this problem.

[0066] In some specific embodiments, the main body 410 is provided with a plurality of flow holes 404, which are arranged in a direction perpendicular to the distribution direction of the first frame 310 and the second frame 320. For example, the first frame 310 and the second frame 320 are arranged in a direction perpendicular to the distribution direction of the second frame 320. Figure 1 If the flow holes are distributed vertically, then multiple flow holes 404 are arranged horizontally.

[0067] In some other embodiments, the main body 410 is provided with a single flow hole 404, which extends for a predetermined length in a direction perpendicular to the distribution direction of the first frame 310 and the second frame 320. For example, the first frame 310 and the second frame 320 extend along... Figure 1 If the flow holes are distributed vertically, then each flow hole 404 extends horizontally.

[0068] When the separator 400 is also used for electrical connection between the first chip 100 and the lead frame 300, in some specific embodiments of the present invention, refer to Figure 6 The separator 400 has a clearance groove 402 on the side facing the lead frame 300, defining the side of the first chip 100 facing the second frame 320 (e.g. Figure 6 The projection of the left side of the chip 100 within the lead frame 300 is the first projection, and the projection of the clearance groove 402 within the lead frame 300 is the second projection. The first projection is located within the second projection; that is, when viewed along the direction from the second chip 200 to the first chip 100, the clearance groove 402 covers the side of the first chip 100 facing the second frame 320. Based on this, refer to... Figure 5 , Figure 6 The first projection and the second projection are spaced apart by a first predetermined distance from the edge of the second frame 320. In other words, the side of the first chip 100 facing the second frame 320 and the wall of the relief groove 402 facing the second frame 320 are spaced apart by a first predetermined distance. For example, the left side of the first chip 100 and the left wall of the relief groove 402 are spaced apart by a first predetermined distance. In this way, the separator 400 can be prevented from contacting the side of the first chip 100 and causing a short circuit.

[0069] In other embodiments, when the first projection is located within the second projection, reference is made. Figure 5 , Figure 6 The first projection and the second projection are spaced apart by a second predetermined distance from the edge of the second frame 320. In other words, the side of the first chip 100 facing the second frame 320 and the wall of the relief groove 402 away from the second frame 320 are spaced apart by a second predetermined distance. For example, the left side of the first chip 100 and the right wall of the relief groove 402 are spaced apart by a second predetermined distance, thereby forming a receiving space with a certain volume between the first chip 100 and the separator 400 to accommodate the solder paste overflowing from between the first chip 100 and the separator 400 during the reflow soldering process, thus avoiding solder crawling.

[0070] When the separator 400 is also used for electrical connection between the first chip 100 and the lead frame 300, in some specific embodiments of the present invention, refer to Figure 1 , Figure 2 The package structure also includes a first lead 800, one end of which is electrically connected to the side of the first chip 100 away from the lead frame 300, for example... Figure 2 On the upper side, the other end is electrically connected to the side of the second chip 200 away from the separator 400, for example... Figure 2 On the upper side of the first chip 100. For example, the second chip 200 has a control circuit inside. One end of a portion of the first lead 800 is electrically connected to the control circuit of the second chip 200, and the other end is connected to the source on the upper side of the first chip 100. One end of another portion of the first lead 800 is electrically connected to the control circuit of the second chip 200, and the other end is connected to the gate on the upper side of the first chip 100.

[0071] In this embodiment, the separator 400 is provided with a clearance hole 403 to avoid the first lead 800. The clearance hole 403 extends along the length of the first lead 800, which can prevent the first lead 800 from contacting the separator 400 and causing a short circuit. To ensure the current carrying capacity of the separator 400, the separator 400 and the first chip 100 need to maintain a certain connection area. This embodiment provides a clearance hole 403, rather than directly shortening the length of the separator 400, to achieve the avoidance of the first lead 800 while ensuring sufficient connection area between the separator 400 and the first chip 100. For example, as shown... Figure 1 As shown, when the first lead 800 is concentrated in the middle of the lower side of the first chip 100, the clearance hole 403 is set in the middle of the lower half of the separator 400, and the separators 400 on the left and right sides of the clearance hole 403 still maintain electrical connection with the first chip 100.

[0072] In addition, the package structure also includes a second lead 900, one end of which is electrically connected to the control circuit of the second chip 200, and the other end is electrically connected to a pin of the package structure for connection with external electrical devices.

[0073] Based on the first embodiment, in some embodiments of this utility model, the projection of the second chip 200 on the lead frame 300 is defined as the third projection, and the projection of the separator 400 on the lead frame 300 is defined as the fourth projection. The third projection is located within the fourth projection, and the distance between the edge of the third projection and the edge of the corresponding side of the fourth projection is greater than or equal to 100 μm. It should be noted that, referring to... Figure 1 In the orientation, "corresponding edge" includes the following meanings: the left edge of the third projection and the left edge of the fourth projection, the right edge of the third projection and the right edge of the fourth projection, the lower edge of the third projection and the lower edge of the fourth projection, and the upper edge of the third projection and the upper edge of the fourth projection. As mentioned above, the separator 400 is usually soldered to the first chip 100 with solder paste. During the reflow soldering process, the separator 400 may shift due to the flow of solder paste, causing the second chip 200 to partially extend beyond the separator 400 when stacked. To solve this problem, in this embodiment, the area of ​​the separator 400 is larger than the area of ​​the second chip 200. For example, the area of ​​the second chip 200 is less than or equal to 60% of the area of ​​the separator 400. On the other hand, by pre-setting the position of the separator 400, it is ensured that even if the separator 400 undergoes maximum displacement in a certain direction, a certain gap will still be maintained between the second chip 200 and the separator 400, thereby preventing the second chip 200 from extending beyond the separator 400.

[0074] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A package structure, characterized by, The package structure comprises: a lead frame; a first chip disposed on one side of the lead frame; a partition disposed on a side of the first chip away from the lead frame; a second chip disposed on a side of the partition away from the first chip; the lead frame, the first chip and the partition are bent in a direction towards or away from the second chip, so that a surface of the partition towards the second chip forms a first curved surface; wherein the package structure further comprises an adhesive disposed between the second chip and the partition, the second chip is adhered to the partition through the adhesive, the adhesive is made of an elastic material, a surface of the adhesive towards the partition forms a second curved surface which is in close contact with the first curved surface, a surface of the adhesive away from the partition forms a flat surface, or a surface of the adhesive away from the partition forms a third curved surface, and the curvature of the third curved surface is smaller than that of the second curved surface.

2. The package structure of claim 1, wherein, The adhesive has a viscoelastic value less than or equal to 300 Pa.s.

3. The package structure of claim 2, wherein, The adhesive has a viscoelastic value greater than or equal to 100 Pa.s.

4. The package structure of claim 1, wherein, The adhesive has an elastic modulus less than or equal to 600 MPa.

5. The package structure of claim 4, wherein, The adhesive has an elastic modulus greater than or equal to 100 MPa.

6. The package structure of claim 1, wherein, In the direction from the first chip to the second chip, the distance between the part closest to the second chip and the part farthest from the second chip of the second curved surface is 8-13 μm.

7. The package structure of claim 1, wherein, The partition is a metal sheet, the adhesive is made of an insulating material, the lead frame comprises a first frame and a second frame arranged at intervals and distributed side by side in a direction parallel to the first chip, the first chip is electrically connected to the first frame, and the partition is electrically connected to the first chip and the second frame respectively.

8. The package structure of claim 7, wherein, The partition comprises a main body and a bent portion, the main body is electrically connected to the first chip, and the bent portion is arranged in a direction towards the lead frame relative to the main body, and the bent portion is electrically connected to the second frame.

9. The package structure of claim 8, wherein, A through hole is arranged through the thickness of the main body between the bent portion and the first chip.

10. The package structure of claim 7, wherein, The partition disposed on a side of the lead frame is provided with a relief groove, the projection of the side edge of the first chip towards the second frame in the lead frame is a first projection, the projection of the relief groove in the lead frame is a second projection, and the first projection is located in the second projection; wherein the first projection and the edge of the second projection towards the second frame are spaced apart by a first specified distance; The package structure further comprises a second layer of tin paste disposed between the first chip and the partition, and the first projection and the edge of the second projection away from the second frame are spaced apart by a second specified distance.

11. The package structure of claim 7, wherein, The packaging structure further comprises a lead, one end of the lead being electrically connected to the side of the first chip away from the lead frame, and the other end of the lead being electrically connected to the side of the second chip away from the partition, the partition being provided with an avoiding hole for avoiding the lead, the avoiding hole extending along the length direction of the lead.

12. The package structure of claim 1, wherein, The projection of the second chip on the lead frame is defined as a third projection, and the projection of the partition on the lead frame is defined as a fourth projection, the third projection being located within the fourth projection, and the distance between the edge of the third projection and the edge of the corresponding side of the fourth projection being greater than or equal to 100 μm.

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