Packaging substrate, packaging structure and forming method thereof

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to a packaging substrate, a packaging structure and a forming method of the packaging structure. The packaging substrate comprises a substrate body which comprises a top surface and a bottom surface which are oppositely distributed; the top welding pad is positioned on the top surface of the substrate body; the bottom welding pad is located on the bottom face of the substrate body, the bottom welding pad comprises a front face facing the substrate body and a back face deviating from the substrate body, and the edge of the bottom welding pad is provided with a groove which is sunken from the back face of the bottom welding pad to the front face of the bottom welding pad. According to the packaging structure, spreading of a plastic packaging material towards the interior of the bottom welding pad can be reduced, the problem of glue overflowing on the back face of the bottom welding pad is effectively reduced, no release film, a supporting rod and other structures need to be additionally arranged, plastic packaging operation is simplified, the yield of the packaging structure is ensured, and the problem that the manufacturing cost of the packaging structure is too high is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, and in particular to a packaging substrate, a packaging structure and a forming method thereof. BACKGROUND

[0002] In the packaging process of a vehicle-mounted power device product, a solder pad at the bottom of an active metal brazing (AMB) ceramic substrate needs to be exposed from a plastic package body, so that the customer can connect with an external carrier by using the exposed bottom solder pad. In order to ensure the stability of the connection between the exposed bottom solder pad and the external carrier, the glue overflow size and area on the exposed bottom solder pad need to be strictly controlled. The glue overflow refers to a phenomenon that the plastic encapsulation material overflows from the edge of the bottom solder pad due to the injection pressure in the process of plastic encapsulation of the AMB with a chip mounted thereon.

[0003] In order to improve the glue overflow problem, there are currently two main solutions: the first solution is to use a support rod to support the AMB, so that the AMB is as flat as possible with the injection mold, thereby improving the glue overflow problem caused by the plastic encapsulation process; the second solution is to try to add a release film on the surface of the plastic encapsulation mold, so that part of the bottom solder pad is embedded in the adhesive material of the release film to realize the close contact between the bottom solder pad and the mold, thereby improving the glue overflow problem caused by the plastic encapsulation process. However, for the first solution, due to the design of the injection mold and the semiconductor structure itself, there is not enough space to balance the distribution of the support rod around the AMB, thereby failing to effectively improve the glue overflow. For the second solution, the addition of the additional release film requires improvement of the injection mold machine, which is high in cost, and due to the need to add a covering and removing process of the release film, the injection efficiency is reduced, the production capacity of the injection mold machine is affected, and the yield of the packaging structure is reduced.

[0004] Therefore, how to effectively reduce the glue overflow problem of the bottom solder pad of the AMB, ensure the yield of the packaging structure, and avoid high manufacturing cost of the packaging structure is a technical problem to be solved at present. SUMMARY

[0005] The present application provides a packaging substrate, a packaging structure and a forming method thereof, for effectively reducing the glue overflow problem of the bottom solder pad of the AMB, ensuring the yield of the packaging structure, and avoiding high manufacturing cost of the packaging structure.

[0006] According to some embodiments, the present application provides a packaging substrate, comprising: a substrate body comprising a top surface and a bottom surface distributed oppositely; a top solder pad located on the top surface of the substrate body; a bottom pad on a bottom surface of the substrate body, the bottom pad including a front surface facing the front surface of the substrate body and a back surface facing away from the back surface of the substrate body, an edge of the bottom pad having a trench recessed from the back surface of the bottom pad toward the front surface of the bottom pad.

[0007] In some embodiments, the bottom pad includes an inner region and a peripheral region distributed around a periphery of the inner region. The trench is located in the peripheral region, and the trench is distributed around the periphery of the inner region.

[0008] In some embodiments, the trench includes: a first trench; a second trench distributed around a periphery of the inner region, and the first trench is distributed around a periphery of the second trench.

[0009] In some embodiments, a depth of the first trench is greater than or equal to a depth of the second trench.

[0010] In some embodiments, a width of the first trench is greater than or equal to a width of the second trench.

[0011] In some embodiments, in a direction perpendicular to the bottom surface of the substrate body, a height of the peripheral region on a side of the first trench facing away from the second trench is lower than a height of the inner region.

[0012] In some embodiments, in a direction perpendicular to the bottom surface of the substrate body, a height of the peripheral region on a side of the first trench facing away from the second trench is higher than a height of the inner region.

[0013] In some embodiments, a width of the peripheral region on a side of the first trench facing away from the second trench is less than a spacing width between the first trench and the second trench.

[0014] In some embodiments, in a direction perpendicular to the bottom surface of the substrate body, a height of the peripheral region between the first trench and the second trench is higher than a height of the inner region.

[0015] In some embodiments, a spacing width between the first trench and the second trench is less than a width of the peripheral region on a side of the first trench facing away from the second trench.

[0016] According to other embodiments, the present application also provides a packaging structure, comprising: A package substrate includes a substrate body having a top surface and a bottom surface, a top solder pad on the top surface of the substrate body, and a bottom solder pad on the bottom surface of the substrate body, the bottom solder pad having a front surface facing the substrate body and a back surface facing away from the substrate body, an edge of the bottom solder pad having a groove recessed from the back surface of the bottom solder pad toward the front surface of the bottom solder pad; a chip mounted on the top solder pad; a molding layer molding the chip and the package substrate, and the back surface of the bottom solder pad being exposed outside the molding layer.

[0017] In some embodiments, the back surface of the bottom solder pad includes an inner region and a peripheral region distributed around a periphery of the inner region; the groove is located in the peripheral region, and the groove is distributed around the periphery of the inner region, and the molding layer is also located in the groove.

[0018] In some embodiments, the groove includes a first groove and a second groove, the second groove being distributed around a periphery of the inner region, and the first groove being distributed around a periphery of the second groove.

[0019] In some embodiments, a depth of the first groove is greater than or equal to a depth of the second groove.

[0020] In some embodiments, in a direction perpendicular to the bottom surface of the substrate body, a height of the peripheral region on a side of the first groove facing away from the second groove is lower than a height of the inner region; the molding layer covers the peripheral region on the side of the first groove facing away from the second groove and fills in the first groove.

[0021] In some embodiments, the peripheral region on the side of the first groove facing away from the second groove is bent toward the first groove, and a surface of the bent peripheral region facing away from the substrate body is flush with a surface of the inner region facing away from the substrate body.

[0022] In some embodiments, a portion of the peripheral region between the first groove and the second groove is bent, and a surface of the bent peripheral region facing away from the substrate body is flush with a surface of the inner region facing away from the substrate body.

[0023] According to yet some embodiments, the present application also provides a method for forming a package structure, including the following steps: forming a package substrate, the package substrate comprising a substrate body, a top solder pad and a bottom solder pad, the substrate body comprising a top surface and a bottom surface oppositely distributed, the top solder pad being located on the top surface of the substrate body, the bottom solder pad being located on the bottom surface of the substrate body, the bottom solder pad comprising a front surface facing the substrate body and a back surface facing away from the substrate body, an edge of the bottom solder pad having a groove recessed from the back surface of the bottom solder pad toward the front surface of the bottom solder pad; attaching a chip on the top solder pad; forming a molding layer molding the chip and the package substrate, and exposing the back surface of the bottom solder pad to outside of the molding layer.

[0024] In some embodiments, the back surface of the bottom solder pad comprises an inner region and a peripheral region peripherally distributed around the inner region, the groove is located in the peripheral region, and the groove is peripherally distributed around the inner region; the specific step of forming a molding layer molding the chip and the package substrate, and exposing the back surface of the bottom solder pad to outside of the molding layer comprises: providing an injection mold comprising a lower mold structure having a lower mold cavity and an upper mold structure having an upper mold cavity; placing the package substrate with the chip attached therein into the lower mold cavity, and controlling the upper mold structure and the lower mold structure to close, so that the bottom solder pad is attached to an inner wall of the upper mold cavity; transferring molding material into a receiving cavity formed by the upper mold cavity and the lower mold cavity, forming the molding layer, and part of the molding material is filled into the groove.

[0025] In some embodiments, the groove comprises a first groove and a second groove, the first groove is peripherally distributed around the second groove, in a direction perpendicular to the bottom surface of the substrate body, a height of the peripheral region on a side of the first groove facing away from the second groove is higher than a height of the inner region, and a width of the peripheral region on the side of the first groove facing away from the second groove is smaller than a spacing width between the first groove and the second groove; when the upper mold structure and the lower mold structure are closed, the part of the peripheral region on the side of the first groove facing away from the second groove, which is higher than the inner region, is bent and flattened to form a gel-blocking surface.

[0026] The packaging substrate, packaging structure and forming method thereof provided by the present application set a groove at the edge of the bottom solder pad in the packaging substrate, and the groove is recessed from the back surface of the bottom solder pad to the front surface of the bottom solder pad, so that during the packaging process of the semiconductor device including the packaging substrate, the overflowed plastic sealing material is collected through the groove, thereby reducing the spread of the plastic sealing material to the inside of the bottom solder pad, effectively reducing the overflow problem of the back surface of the bottom solder pad, without the need for additional structures such as release film and support rod, simplifying the plastic sealing operation, ensuring the yield of the packaging structure, and avoiding the problem of high manufacturing cost of the packaging structure. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a cross-sectional schematic view of a packaging substrate in the specific embodiment of the present application; Figure 2 is a top view schematic view of a packaging substrate in the specific embodiment of the present application; Figure 3 is a cross-sectional schematic view of a bottom solder pad after plastic sealing in the specific embodiment of the present application; Figure 4 is a top view schematic view of another packaging substrate in the specific embodiment of the present application; Figure 5 is a structural schematic view of another bottom solder pad before plastic sealing in the specific embodiment of the present application; Figure 6 is a structural schematic view of another bottom solder pad during plastic sealing in the specific embodiment of the present application; Figure 7 is a structural schematic view of still another bottom solder pad before plastic sealing in the specific embodiment of the present application; Figure 8 is a structural schematic view of still another bottom solder pad during plastic sealing in the specific embodiment of the present application; Figure 9 is a cross-sectional schematic view of a packaging structure in the specific embodiment of the present application; Figure 10 is a flowchart of the forming method of a packaging structure in the specific embodiment of the present application. DETAILED DESCRIPTION

[0028] The specific embodiments of the packaging substrate, packaging structure and forming method thereof provided by the present application will be described in detail below with reference to the accompanying drawings.

[0029] The specific embodiment provides a packaging substrate, Figure 1 is a cross-sectional schematic view of a packaging substrate in the specific embodiment of the present application, Figure 2 is a top view schematic view of a packaging substrate in the specific embodiment of the present application, Figure 3is a sectional view of a bottom pad after plastic packaging in the embodiment of the present application. As shown in Figures 1-3 the packaging substrate comprises: a substrate body 10 comprising a top surface 101 and a bottom surface 102 oppositely distributed; a top pad 11 located on the top surface 101 of the substrate body 10; a bottom pad 12 located on the bottom surface 102 of the substrate body 10, the bottom pad 12 comprising a front surface facing the substrate body 10 and a back surface away from the substrate body 10, and the edge of the bottom pad 12 having a groove recessed from the back surface of the bottom pad 12 towards the front surface of the bottom pad 12.

[0030] In an example, the packaging substrate is an AMB substrate. For example, the substrate body 10 is a ceramic plate. The top pad 11 is brazed on the top surface 101 of the substrate body 10, and the bottom pad 12 is brazed on the bottom surface 102 of the substrate body 10. In an example, the material of the top pad 11 and the material of the bottom pad 12 both comprise copper. The top pad 11 is used for mounting functional chips or surface components, and the bottom pad 12 is used for electrical connection with external devices. By providing the groove at the edge of the bottom pad 12 in the embodiment, and the groove extends from the back surface of the bottom pad 12 towards the inside of the bottom pad 12, and the groove does not penetrate the bottom pad 12 in the direction perpendicular to the back surface of the bottom pad 12, so that during the process of plastic packaging of the packaging substrate by using plastic packaging material, the overflowed plastic packaging material can be collected through the groove at the edge of the bottom pad 12, so as to reduce or even avoid the spread of plastic packaging material to the inside of the bottom pad, effectively reducing the overflow problem of the back surface of the bottom pad, ensuring that the bottom pad 12 can be stably electrically connected with external devices subsequently, and without the need of additionally providing structures such as release film and supporting rod, simplifying the plastic packaging operation, ensuring the yield of the packaging structure, and avoiding the problem of excessively high manufacturing cost of the packaging structure.

[0031] In some embodiments, the bottom pad 12 comprises an inner region P1 and a peripheral region P2 distributed around the outer periphery of the inner region P1; the groove is located in the peripheral region P2, and the groove is distributed around the inner region P1.

[0032] For example, the bottom pad 12 includes the inner region P1 and the peripheral region P2 distributed around the outer periphery of the inner region P1, and a metal plating layer can be provided on the inner region P1 to facilitate electrical connection with external devices. In an example, the metal plating layer can be a silver plating layer. The trench is located in the peripheral region P2, thereby avoiding occupying the area of the metal plating layer. The trench is distributed around the outer periphery of the inner region P1, thereby being able to more fully and uniformly avoid overflow of the inner region P1.

[0033] In some embodiments, the trench includes: a first trench 21; a second trench 22 distributed around the outer periphery of the inner region P1, and the first trench 21 is distributed around the outer periphery of the second trench 22.

[0034] In particular, the trench includes the first trench 21 and the second trench 22 both located in the peripheral region P2, and the first trench 21 is distributed around the outer periphery of the second trench 22. By providing two trenches, the space of the trench for accommodating the overflow of the plastic packaging material can be increased, thereby being able to better reduce the overflow problem on the inner region P1. Moreover, the first trench 21 can also be used to collect the plastic packaging material and prevent the overflow of the plastic packaging material from further overflowing, and the amount of the plastic packaging material collected in the second trench 22 can be used to intuitively determine whether the overflow amount is within the standard range, thereby being able to intuitively determine whether the packaging structure is defective.

[0035] In some embodiments, the depth of the first trench 21 is greater than or equal to the depth of the second trench 22, so as to sufficiently collect the overflow of the plastic packaging material by the first trench 21 and reduce the plastic packaging material overflowing into the second trench 22.

[0036] In some embodiments, the width of the first trench 21 is greater than or equal to the width of the second trench 22, so as to sufficiently collect the overflow of the plastic packaging material by the first trench 21 and reduce the plastic packaging material overflowing into the second trench 22.

[0037] In some embodiments, in a direction perpendicular to the bottom surface 102 of the substrate body 10, the height of the peripheral region P2 on the side of the first trench 21 away from the second trench 22 is lower than the height of the inner region P1.

[0038] In one example, the height of the peripheral region P2 of the first trench 21 on the side facing away from the second trench 22 is lower than the height of the inner region P1, which means that the thickness of the bottom pad 12 of the peripheral region P2 of the first trench 21 on the side facing away from the second trench 22 is less than the thickness of the bottom pad 12 of the inner region P1, and the front surface of the bottom pad 12 of the peripheral region P2 is flush with the front surface of the bottom pad 12 of the inner region P1. For example, the height of the peripheral region P2 of the first trench 21 on the side facing away from the second trench 22 is lower than the height of the inner region P1, and the height of the peripheral region P2 of the first trench 21 on the side facing away from the second trench 22 is lower than the height of the peripheral region P2 of the first trench 21 on the side facing toward the second trench 22. On the one hand, the narrow passage (i.e., the narrow passage on the peripheral surface) formed by the gap between the bottom pad 12 of the peripheral region P2 with a lower height and the plastic packaging mold can be used to avoid the passage of plastic packaging material particles of a larger size, thereby controlling the amount of plastic packaging material 30 overflowing into the first trench 21. On the other hand, as the plastic packaging material 30 slowly overflows the first trench 21, the viscosity of the plastic packaging material 30 located in the first trench 21 and on the peripheral region P2 of the bottom pad 12 increases sharply, thereby naturally forming a blocking layer to prevent the plastic packaging material from further overflowing into the second trench 22. Even if a small amount of plastic packaging material 30 overflows into the second trench 22, it will flow along the extension direction of the second trench 22 and will not further overflow into the inner region P1.

[0039] Figure 4 is a top view of another package substrate in the embodiment of the present application, Figure 5 is a structural view of another bottom pad before plastic packaging in the embodiment of the present application, Figure 6 is a structural view of another bottom pad during plastic packaging in the embodiment of the present application. In other embodiments, as shown in Figures 4-6 , in the direction perpendicular to the bottom surface 102 of the substrate body 10, the height of the peripheral region P2 of the first trench 21 on the side facing away from the second trench 22 is higher than the height of the inner region P1.

[0040] In some embodiments, the width of the peripheral region P2 of the first trench 21 on the side facing away from the second trench 22 is less than the interval width between the first trench 21 and the second trench 22.

[0041] In one example, the height of the peripheral region P2 on the side of the first trench 21 facing away from the second trench 22 is higher than the height of the inner region P1 means that the thickness of the bottom pad 12 of the peripheral region P2 on the side of the first trench 21 facing away from the second trench 22 is greater than the thickness of the bottom pad 12 of the inner region P1, and the front surface of the bottom pad 12 of the peripheral region P2 is flush with the front surface of the bottom pad 12 of the inner region P1. For example, as shown in Figures 4-6 the height of the peripheral region P2 on the side of the first trench 21 facing away from the second trench 22 is higher than the height of the inner region P1, and the height of the peripheral region P2 on the side of the first trench 21 facing away from the second trench 22 is higher than the height of the peripheral region P2 on the side of the first trench 21 facing toward the second trench 22, so that the peripheral region P2 on the side of the first trench 21 facing away from the second trench 22 forms a structure similar to a burr. Under the action of the clamping pressure of the injection mold 60, the part of the peripheral region P2 on the side of the first trench 21 facing away from the second trench 22 that is higher than the inner region P1 is bent and flattened to form a glue-blocking surface, thereby preventing the plastic sealing material 30 from overflowing into the first trench 21. Even if part of the region exists due to the fact that the clamping is not tight, the plastic sealing material 30 will overflow into the first trench 21, the overflowed plastic sealing material 30 will flow along the extension direction of the first trench 21 (i.e., the direction surrounding the inner region P1) and solidify, and will not overflow into the second trench 22.

[0042] Figure 7 is another structure diagram of a bottom pad before plastic sealing in the embodiment of the present application, Figure 8 is another structure diagram of a bottom pad during plastic sealing in the embodiment of the present application. In other embodiments, as shown in Figure 7 and Figure 8 In the direction perpendicular to the bottom surface 102 of the substrate body 10, the height of the peripheral region P2 between the first trench 21 and the second trench 22 is higher than the height of the inner region P1.

[0043] In some embodiments, the interval width between the first trench 21 and the second trench 22 is smaller than the width of the peripheral region P2 on the side of the first trench 21 facing away from the second trench 22.

[0044] In one example, the height of the peripheral region P2 between the first trench 21 and the second trench 22 is higher than the height of the inner region P1 means that the thickness of the bottom pad 12 of the peripheral region P2 between the first trench 21 and the second trench 22 is greater than the thickness of the bottom pad 12 of the inner region P1, and the front surface of the bottom pad 12 of the peripheral region P2 is flush with the front surface of the bottom pad 12 of the inner region P1. For example, as shown in Figure 7 and Figure 8 the height of the peripheral region P2 between the first trench 21 and the second trench 22 is higher than the height of the inner region P1, and the height of the peripheral region P2 between the first trench 21 and the second trench 22 is higher than the height of the peripheral region P2 on the side of the first trench 21 away from the second trench 22, so that the peripheral region P2 between the first trench 21 and the second trench 22 forms a structure similar to a burr. Under the action of the clamping pressure of the injection mold 60, the part of the peripheral region P2 between the first trench 21 and the second trench 22 that is higher than the inner region P1 is bent and flattened to form a glue-blocking surface, and the surface of the bent peripheral region P2 away from the substrate body 10 is flush with the surface of the inner region P1 away from the substrate body 10, thereby preventing the plastic package material 30 from overflowing into the second trench 22. Even if part of the region exists due to the fact that the clamping is not tight, and part of the plastic package material 30 overflows into the first trench 21, the overflowing plastic package material 30 will flow along the extension direction of the first trench 21 (i.e., the direction surrounding the inner region P1) and solidify, and will not overflow into the second trench 22.

[0045] In still other embodiments, in the direction perpendicular to the bottom surface 102 of the substrate body 10, the height of the peripheral region P2 on the side of the first trench 21 away from the second trench 22 is higher than the height of the inner region P1, and the height of the peripheral region P2 between the first trench 21 and the second trench 22 is higher than the height of the inner region P1, so that under the action of the clamping pressure of the injection mold 60, the part of the peripheral region P2 on the side of the first trench 21 away from the second trench 22 that is higher than the inner region P1 is bent and flattened to form a glue-blocking surface, and the part of the peripheral region P2 between the first trench 21 and the second trench 22 that is higher than the inner region P1 is bent and flattened to form another glue-blocking surface, and the two glue-blocking surfaces can more fully prevent the plastic package material from overflowing.

[0046] The specific embodiment also provides a packaging structure, Figure 9is a schematic view of a cross section of the packaging structure in the embodiment. The structure of the packaging substrate in the packaging structure can be seen from Figures 1-6 . As shown in Figures 1-9 , the packaging structure comprises: a packaging substrate comprising a substrate body 10, a top solder pad 11 and a bottom solder pad 12, the substrate body 10 comprising a top surface 101 and a bottom surface 102 oppositely distributed, the top solder pad 11 being located on the top surface 101 of the substrate body 10, the bottom solder pad 12 being located on the bottom surface 102 of the substrate body 10, the bottom solder pad 12 comprising a front surface facing the substrate body 10 and a back surface away from the substrate body 10, the edge of the bottom solder pad 12 having a groove recessed from the back surface of the bottom solder pad 12 towards the front surface of the bottom solder pad 12; a chip 70 mounted on the top solder pad 11; a plastic encapsulation layer 72 encapsulating the chip 70 and the packaging substrate, and the back surface of the bottom solder pad 12 being exposed outside the plastic encapsulation layer 72.

[0047] Specifically, the chip 70 is mounted on the top solder pad 11 and electrically connected with the top solder pad 11. In an example, the packaging structure further comprises a plurality of pins 71, and a part of the pins 71 are electrically connected with the chip 70, and another part of the pins 71 are electrically connected with the top solder pad 11. The plastic encapsulation layer 72 continuously encapsulates the chip 70, the pins 71 and the packaging substrate, and the back surface of the bottom solder pad 12 in the packaging substrate is exposed outside the plastic encapsulation layer 72, and a part of the pins 71 extends out of the plastic encapsulation layer 72. The material of the plastic encapsulation layer 72 can be epoxy resin plastic encapsulation material.

[0048] The embodiment can collect the overflowed plastic encapsulation material through the groove at the edge of the bottom solder pad 12 during the process of forming the plastic encapsulation layer 72 encapsulating the packaging substrate and the chip 70 by using plastic encapsulation material, so as to reduce or even avoid the spread of the plastic encapsulation material to the inside of the bottom solder pad 12, effectively reduce the overflow problem of the back surface of the bottom solder pad 12, ensure that the bottom solder pad 12 can be stably electrically connected with external devices in the future, and simplify the plastic encapsulation operation without the need of additionally setting structures such as release film and supporting rod, ensure the yield of the packaging structure, and avoid the problem of excessively high manufacturing cost of the packaging structure.

[0049] In some embodiments, the back surface of the bottom pad 12 comprises an inner region P1 and a peripheral region P2 distributed around the outer periphery of the inner region P1; The trench is located in the peripheral region P2, and the trench is distributed around the inner region P1. The plastic encapsulation layer 72 is also located in the trench.

[0050] In some embodiments, the trench comprises a first trench 21 and a second trench 22. The second trench 22 is distributed around the outer periphery of the inner region P1, and the first trench 21 is distributed around the outer periphery of the second trench 22.

[0051] The specific embodiment can increase the space of the trench to accommodate the overflow of the plastic encapsulation material, thereby better reducing the overflow problem of the inner region P1. Moreover, the first trench 21 can collect the plastic encapsulation material and prevent the overflow of the plastic encapsulation material. The amount of the plastic encapsulation material collected in the second trench 22 can be used to intuitively determine whether the overflow is within the standard range, thereby determining whether the packaging structure is defective.

[0052] In some embodiments, the depth of the first trench 21 is greater than or equal to the depth of the second trench 22, so as to sufficiently collect the overflow of the plastic encapsulation material through the first trench 21 and reduce the overflow of the plastic encapsulation material to the second trench 22.

[0053] In some embodiments, as shown in Figure 3 and Figure 9 In the direction perpendicular to the bottom surface 102 of the substrate body 10, the height of the peripheral region P2 on the side of the first trench 21 away from the second trench 22 is lower than the height of the inner region P1. The plastic encapsulation layer 72 covers the peripheral region P2 on the side of the first trench 21 away from the second trench 22 and fills in the first trench 21.

[0054] In other embodiments, as shown in Figure 5 , Figure 6 and Figure 9 The peripheral region P2 on the side of the first trench 21 away from the second trench 22 is bent towards the first trench 22. The bent peripheral region P2 is flush with the surface of the substrate body 10 on the side of the inner region P1.

[0055] The specific embodiment also provides a method for forming a packaging structure, Figure 10 is a flowchart of the method for forming a packaging structure in the specific embodiment of the present application. The schematic diagram of the packaging structure formed by the specific embodiment can be seen inFigure 9 , and the schematic diagram of the package substrate in the package structure formed by the embodiment is shown in Figures 1-8 . As shown in Figures 1-10 , the forming method of the package structure comprises the following steps: Step S81, forming a package substrate, the package substrate comprises a substrate body 10, a top solder pad 11 and a bottom solder pad 12, the substrate body 10 comprises a top surface 101 and a bottom surface 102 oppositely distributed, the top solder pad 11 is located on the top surface 101 of the substrate body 10, the bottom solder pad 12 is located on the bottom surface 102 of the substrate body 10, the bottom solder pad 12 comprises a front surface facing the substrate body 10 and a back surface facing away from the substrate body 10, and the edge of the bottom solder pad 12 has a groove recessed from the back surface of the bottom solder pad 12 towards the front surface of the bottom solder pad 12; Step S82, mounting a chip 70 on the top solder pad 11; Step S83, forming a plastic encapsulation layer 72 for plastic encapsulating the chip 70 and the package substrate, and exposing the back surface of the bottom solder pad 12 to the outside of the plastic encapsulation layer 72.

[0056] In some embodiments, the back surface of the bottom solder pad 12 comprises an inner region P1 and a peripheral region P2 distributed around the outer periphery of the inner region P1, the groove is located in the peripheral region P2, and the groove is distributed around the inner region P1; the specific step of forming the plastic encapsulation layer 72 for plastic encapsulating the chip 70 and the package substrate, and exposing the back surface of the bottom solder pad 12 to the outside of the plastic encapsulation layer 72 comprises: providing an injection mold, the injection mold comprises a lower mold structure having a lower mold cavity and an upper mold structure having an upper mold cavity; placing the package substrate with the chip 70 mounted thereon into the lower mold cavity, and controlling the upper mold structure and the lower mold structure to close, so that the bottom solder pad 12 is attached to the inner wall of the upper mold cavity; transferring plastic encapsulation material into the containing cavity formed by the upper mold cavity and the lower mold cavity, forming the plastic encapsulation layer 72, and part of the plastic encapsulation material is filled into the groove.

[0057] Specifically, since the back surface of the bottom solder pad 12 is attached to the inner wall of the upper mold cavity, when the plastic encapsulation material is transferred into the containing cavity of the injection mold, the overflowed plastic encapsulation material is collected by the first groove 21 and prevented from further overflowing to the inner region P1 of the bottom solder pad 12, thereby improving the overflow problem of the back surface of the bottom solder pad 12.

[0058] In some embodiments, the groove includes a first groove 21 and a second groove 22, the first groove 21 and the second groove 22 are distributed around the outer periphery of the inner region P1, and the first groove 21 is distributed around the outer periphery of the second groove 22, in the direction perpendicular to the bottom surface 102 of the substrate body 10, the height of the peripheral region P2 on the side of the first groove 21 away from the second groove 22 is higher than the height of the inner region P1, and the width of the peripheral region P2 on the side of the first groove 21 away from the second groove 22 is smaller than the interval width between the first groove 21 and the second groove 22; when the upper mold structure and the lower mold structure are closed, the part of the peripheral region P2 on the side of the first groove 21 away from the second groove 22 that is higher than the inner region P1 is bent and flattened to form a glue-blocking surface, thereby preventing the plastic encapsulating material 30 from overflowing into the first groove 21; even if part of the region has plastic encapsulating material 30 overflowing into the first groove 21 due to the lack of tightness of the pressing, the overflowing plastic encapsulating material 30 will flow along the extension direction of the first groove 21 (i.e., the direction around the inner region P1) and solidify, and will not overflow into the second groove 22.

[0059] The packaging substrate, packaging structure and forming method thereof provided by the specific embodiment can collect the overflowing plastic encapsulating material through the groove in the process of packaging the semiconductor device including the packaging substrate, thereby reducing the spreading of the plastic encapsulating material to the inside of the bottom solder pad, effectively reducing the overflow problem of the bottom solder pad back surface, without the need for additional structures such as release film and support rod, simplifying the plastic encapsulating operation, ensuring the yield of the packaging structure, and avoiding the problem of excessively high manufacturing cost of the packaging structure.

[0060] The above only describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A package substrate, characterized by, Comprising: a substrate body including a top surface and a bottom surface oppositely distributed; a top pad located on the top surface of the substrate body; a bottom pad located on the bottom surface of the substrate body, the bottom pad including a front surface facing the substrate body and a back surface facing away from the substrate body, an edge of the bottom pad having a groove recessed from the back surface of the bottom pad toward the front surface of the bottom pad.

2. The package substrate of claim 1, wherein The bottom pad includes an inner region and a peripheral region peripherally distributed around the inner region; The groove is located in the peripheral region, and the groove is peripherally distributed around the inner region.

3. The package substrate of claim 2, wherein, The groove includes: a first groove; a second groove peripherally distributed around an outer periphery of the inner region, and the first groove peripherally distributed around an outer periphery of the second groove.

4. The package substrate of claim 3, wherein The depth of the first groove is greater than or equal to the depth of the second groove.

5. The package substrate of claim 3, wherein The width of the first groove is greater than or equal to the width of the second groove.

6. The package substrate of claim 3, wherein In a direction perpendicular to the bottom surface of the substrate body, the height of the peripheral region on the side of the first groove facing away from the second groove is lower than the height of the inner region.

7. The package substrate of claim 3, wherein In a direction perpendicular to the bottom surface of the substrate body, the height of the peripheral region on the side of the first groove facing away from the second groove is higher than the height of the inner region.

8. The package substrate of claim 7, wherein, The width of the peripheral region on the side of the first groove facing away from the second groove is less than the spacing width between the first groove and the second groove.

9. The package substrate of claim 3, wherein, In a direction perpendicular to the bottom surface of the substrate body, the height of the peripheral region between the first groove and the second groove is higher than the height of the inner region.

10. The package substrate of claim 9, wherein, The spacing width between the first groove and the second groove is less than the width of the peripheral region on the side of the first groove facing away from the second groove.

11. A package structure, characterized by, Comprising: a package substrate including a substrate body, a top pad, and a bottom pad, the substrate body including a top surface and a bottom surface oppositely distributed, the top pad located on the top surface of the substrate body, the bottom pad located on the bottom surface of the substrate body, the bottom pad including a front surface facing the substrate body and a back surface facing away from the substrate body, an edge of the bottom pad having a groove recessed from the back surface of the bottom pad toward the front surface of the bottom pad; a chip mounted on the top pad; a molding layer molding the chip and the package substrate, and the back surface of the bottom pad exposed outside the molding layer.

12. The package structure of claim 11, wherein, The back surface of the bottom pad includes an inner region and a peripheral region peripherally distributed around the inner region; The groove is located in the peripheral region, and the groove is peripherally distributed around the inner region, and the molding layer is also located in the groove.

13. The package structure of claim 12, wherein, The groove includes a first groove and a second groove, the second groove peripherally distributed around an outer periphery of the inner region, and the first groove peripherally distributed around an outer periphery of the second groove.

14. The package structure of claim 13, wherein, The depth of the first groove is greater than or equal to the depth of the second groove.

15. The package structure of claim 13, wherein, In a direction perpendicular to the bottom surface of the substrate body, the height of the peripheral region on the side of the first groove facing away from the second groove is lower than the height of the inner region; The plastic encapsulation layer covers the peripheral area of the first groove on the side facing away from the second groove and fills the first groove.

16. The package structure of claim 13, wherein, The peripheral area of the first groove on the side facing away from the second groove is bent towards the first groove, and the bent peripheral area is flush with the surface of the substrate body on the side facing away from the substrate body.

17. The package structure of claim 13, wherein, The peripheral area between the first groove and the second groove is bent, and the bent peripheral area is flush with the surface of the substrate body on the side facing away from the substrate body.

18. A method of forming a package structure, comprising: The method comprises the following steps: forming a packaging substrate, the packaging substrate comprising a substrate body, a top solder pad and a bottom solder pad, the substrate body comprising oppositely distributed top and bottom surfaces, the top solder pad being located on the top surface of the substrate body, the bottom solder pad being located on the bottom surface of the substrate body, the bottom solder pad comprising a front surface facing the substrate body and a back surface facing away from the substrate body, the edge of the bottom solder pad having a groove recessed from the back surface of the bottom solder pad towards the front surface of the bottom solder pad; attaching a chip to the top solder pad; forming a plastic encapsulation layer encapsulating the chip and the packaging substrate, and exposing the back surface of the bottom solder pad to the outside of the plastic encapsulation layer.

19. The method of claim 18, wherein The back surface of the bottom solder pad comprises an inner area and a peripheral area distributed around the outer periphery of the inner area, the groove is located in the peripheral area, and the groove is distributed around the inner area; The specific step of forming a plastic encapsulation layer encapsulating the chip and the packaging substrate, and exposing the back surface of the bottom solder pad to the outside of the plastic encapsulation layer comprises: providing an injection mold comprising a lower mold structure having a lower mold cavity and an upper mold structure having an upper mold cavity; placing the packaging substrate with the chip attached in the lower mold cavity, and controlling the upper mold structure and the lower mold structure to close, so that the bottom solder pad is attached to the inner wall of the upper mold cavity; transferring plastic encapsulation material into the containing cavity formed by the upper mold cavity and the lower mold cavity to form the plastic encapsulation layer, and part of the plastic encapsulation material fills into the groove.

20. The method of claim 19, wherein The groove comprises a first groove and a second groove, the first groove is distributed around the outer periphery of the second groove, in the direction perpendicular to the bottom surface of the substrate body, the height of the peripheral area of the first groove on the side facing away from the second groove is higher than the height of the inner area, and the width of the peripheral area of the first groove on the side facing away from the second groove is smaller than the interval width between the first groove and the second groove; When the upper mold structure and the lower mold structure are closed, the part of the peripheral area of the first groove on the side facing away from the second groove that is higher than the inner area is bent and flattened to form a gel-blocking surface.

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