Packaging structure and forming method of packaging structure

Abstract

According to the packaging structure and the forming method of the packaging structure, when the packaging structure works, heat generated by a first chip can be directly conducted outwards through a first base island in contact with the first chip and the side, exposed out of a plastic packaging layer, of the first base island; similarly, heat generated by the second chip is conducted to the outside through the exposed side of the second base island. Therefore, the packaging structure constructs a double-sided and three-dimensional heat dissipation channel, heat is conducted out from two opposite surfaces of the packaging structure at the same time, compared with a single-surface heat dissipation structure, the total heat dissipation area is increased, heat concentration is avoided, the overall thermal resistance of the packaging structure is reduced, the packaging structure can bear higher power density, and the packaging structure is more compact. The power processing capability of the packaging structure is improved, the influence of thermal stress on the device is reduced, and the overall service life of the device is prolonged.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of semiconductor packaging, and in particular to a packaging structure and a method for forming the packaging structure. Background Art

[0002] In the field of integrated circuit chip heat dissipation, as chip integration continues to increase and operating frequencies continue to climb, chip heat generation continues to increase. To ensure that chips can operate stably within the appropriate temperature range and avoid problems such as performance degradation, shortened service life, and even damage caused by overheating, heat dissipation technology has always been a key research direction in the chip packaging field.

[0003] Traditional chip packaging heat dissipation structures primarily utilize two methods. One involves placing the chip on a frame and exposing the backside of the frame to dissipate heat. This allows heat to be conducted from the bottom of the chip to the backside of the frame and ultimately dissipated into the surrounding environment. The other involves stacking a heat sink on top of the flip-chip and exposing it, allowing heat exchange between the heat sink and the air.

[0004] At present, the two traditional heat dissipation methods can meet the heat dissipation needs of chips to a certain extent, but their heat dissipation has limitations. Summary of the Invention

[0005] The problem solved by the embodiments of the present invention is to provide a packaging structure and a method for forming the packaging structure, thereby increasing the total heat dissipation area and reducing the overall thermal resistance of the packaging structure.

[0006] To solve the above problems, an embodiment of the present invention provides a packaging structure, including: a lead frame, the lead frame including a first base island, a second base island, and pins located around the first base island and the second base island, the pins having a first end close to the first base island and the second base island in a horizontal direction and a second end away from the first base island and the second base island, the first base island and the second base island being spaced apart and at different height positions; a first chip, located on a side of the first base island close to the second base island in a height direction; a first lead, connecting the first chip to at least one pin around the first chip; a second chip, located on a side of the second base island close to the first base island in a height direction; a second lead, connecting the second chip to at least one pin around the second chip; a plastic layer, located on the lead frame, the plastic layer encapsulating the first chip, the second chip, the first lead, and the second lead, and the plastic layer exposing a side of the first base island and the second end of the pin facing away from the first chip and a side of the second base island facing away from the second chip in a height direction.

[0007] Optionally, the pin includes a ground pin, a first end of the ground pin is connected to a side of the second base island, and a second end of the ground pin is in the same horizontal plane as the first base island.

[0008] Optionally, the ground pin and the second base island are an integrated structure.

[0009] Optionally, the grounding pin includes an inclined portion that is angled relative to a horizontal plane, and the inclined portion is used to enable the second end of the grounding pin and the first end of the grounding pin to be at different height positions.

[0010] Optionally, the ground pin is at least located on a side of the second base island facing away from the first base island.

[0011] Optionally, the ground pin includes at least one step surface structure.

[0012] Optionally, the second lead is connected to any one of the step surfaces of the ground pin.

[0013] Optionally, the first base island and the second base island are arranged along a first direction, the first direction is perpendicular to the second direction, the first end and the second end of the pin on the side of the second base island away from the first base island are in different horizontal planes, and the first end and the second end of the pin on both sides of the second direction of the second base island are in different horizontal planes.

[0014] Optionally, the height positions of the first ends of the pins on both sides of the second base island in the second direction are located between the first base island and the second base island, and the second ends of the pins on both sides of the second base island in the second direction are in the same horizontal plane as the first base island.

[0015] Optionally, the pins include non-ground pins, and the non-ground pins are spaced apart from the first base island and the second base island.

[0016] Optionally, the pin located on a side of the first base island facing away from the second base island is formed in the same horizontal plane as the first base island.

[0017] Optionally, the first base island and the second base island are arranged along a first direction, and the first direction is perpendicular to the second direction; the first lead connects the first chip to the pins on both sides of the first chip in the second direction, and the first lead also connects the first chip to the pins on the side of the first base island away from the second base island.

[0018] Optionally, the first base island and the second base island are arranged along a first direction, and the first direction is perpendicular to the second direction; the second lead connects the second chip to the pins on both sides of the second chip in the second direction, and the second lead also connects the second chip to the pins on the side of the second base island away from the first base island.

[0019] Optionally, in the height direction perpendicular to the first base island and the second base island, the area of ​​the surface of the first base island facing away from the second base island is smaller than the area of ​​the surface of the first base island close to the second base island, and the area of ​​the surface of the second base island facing away from the first base island is smaller than the area of ​​the surface of the second base island close to the first base island.

[0020] Optionally, the first base island and the second base island both have a stepped block structure, and the bottom of the first base island and the bottom of the second base island are arranged opposite to each other.

[0021] Optionally, the packaging structure further includes: a substrate located on a side of the first base island away from the first chip; and a heat dissipation structure located on a side of the second base island away from the second chip.

[0022] Optionally, the material of the lead frame includes copper.

[0023] An embodiment of the present invention also provides a method for forming a packaging structure, comprising: providing a lead frame, the lead frame comprising a first base island, a second base island, and pins located around the first base island and the second base island, the pins having a first end close to the first base island and the second base island in a horizontal direction and a second end away from the first base island and the second base island, the first base island and the second base island being spaced apart and at different heights; mounting a first chip on a side of the first base island close to the second base island in a height direction; connecting the first chip to at least one pin around the first chip through a first lead; mounting a second chip on a side of the second base island close to the first base island in a height direction; connecting the second chip to at least one pin around the second chip through a second lead; performing plastic sealing on the lead frame to form a plastic sealing layer to encapsulate the first chip, the second chip, the first lead, and the second lead, the plastic sealing layer exposing a side of the first base island and the second end of the pin facing away from the first chip and a side of the second base island facing away from the second chip in a height direction.

[0024] Optionally, in the step of providing a lead frame, the pin includes a ground pin, a first end of the ground pin is connected to a side of the second base island, and a second end of the ground pin is in the same horizontal plane as the first base island.

[0025] Optionally, in the step of providing a lead frame, the ground pin and the second base island are an integrated structure.

[0026] Optionally, in the step of providing the lead frame, the grounding pin includes an inclined portion at an angle relative to a horizontal plane, and the inclined portion is used to enable the second end of the grounding pin and the first end of the grounding pin to be at different height positions.

[0027] Optionally, in the step of providing a lead frame, the grounding pin is formed at least on a side of the second base island facing away from the first base island.

[0028] Optionally, in the step of providing a lead frame, the ground pin includes at least one stepped surface structure.

[0029] Optionally, in the step of forming the second lead, the second lead is connected to any one of the step surfaces of the ground pin.

[0030] Optionally, in the step of providing a lead frame, the first base island and the second base island are arranged along a first direction, the first direction is perpendicular to the second direction, the first end and the second end of the pin on the side of the second base island away from the first base island are in different horizontal planes, and the first end and the second end of the pin on both sides of the second base island in the second direction are in different horizontal planes.

[0031] Optionally, in the step of providing a lead frame, the height positions of the first ends of the pins on both sides of the second base island in the second direction are located between the first base island and the second base island, and the second ends of the pins on both sides of the second base island in the second direction are in the same horizontal plane as the first base island.

[0032] Optionally, in the step of providing a lead frame, the pins include non-ground pins, and the non-ground pins are spaced apart from the first base island and the second base island.

[0033] Optionally, in the step of providing the lead frame, the pins formed on the side of the first base island facing away from the second base island are formed in the same horizontal plane as the first base island.

[0034] Optionally, the step of providing a lead frame includes performing a stamping process, a bending process, or a convex process on at least a portion of the lead frame.

[0035] Optionally, the method for forming the packaging structure further includes: after connecting the first chip to at least one pin around the first chip through a first lead, and before mounting the second chip on the second base island, flipping the lead frame.

[0036] Optionally, in the step of providing a lead frame, the first base island and the second base island are arranged along a first direction, and the first direction is perpendicular to the second direction; in the step of forming the first lead, the first lead connects the first chip to the pins on both sides of the first chip in the second direction, and the first lead also connects the first chip to the pins on the side of the first base island away from the second base island.

[0037] Optionally, in the step of providing a lead frame, the first base island and the second base island are arranged along a first direction, and the first direction is perpendicular to the second direction; in the step of forming the second lead, the second lead connects the second chip to the pins on both sides of the second chip in the second direction, and the second lead also connects the second chip to the pins on the side of the second base island away from the first base island.

[0038] Optionally, in the step of providing a lead frame, in the height direction perpendicular to the first base island and the second base island, the area of ​​the surface of the first base island facing away from the second base island is smaller than the area of ​​the surface of the first base island close to the second base island, and the area of ​​the surface of the second base island facing away from the first base island is smaller than the area of ​​the surface of the second base island close to the first base island.

[0039] Optionally, in the step of providing the lead frame, the first base island and the second base island both have a stepped block structure, and the bottom of the first base island and the bottom of the second base island are arranged opposite to each other.

[0040] Optionally, the step of performing molding on the lead frame to form a molding layer includes: forming a first protective film on the lead frame on the side of the first base island facing away from the first chip, and on the side of the second end of the pin facing away from the first chip; forming a second protective film on the lead frame on the side of the second base island facing away from the second chip, and making the pin located between the first protective film and the second protective film; injecting molding material between the first protective film and the second protective film, the molding material encapsulating the first chip, the second chip, the first lead, the second lead and the pin; curing the molding material to form the molding layer; the method for forming the packaging structure also includes: after forming the molding layer, removing the first protective film and the second protective film, so that the first base island and the second end of the pin facing away from the first chip and the side of the second base island facing away from the second chip are exposed.

[0041] Optionally, the method for forming the packaging structure also includes: after performing plastic sealing on the lead frame to form a plastic sealing layer, attaching the first base island and the second end of the pin on the side facing away from the first chip to the substrate; after performing plastic sealing on the lead frame to form a plastic sealing layer, forming a heat dissipation structure on the side of the second base island facing away from the second chip.

[0042] Optionally, the material of the lead frame includes copper.

[0043] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0044] In the packaging structure provided by an embodiment of the present invention, a first base island and a second base island are spaced apart and positioned at different heights, with the first chip located on the side of the first base island close to the second base island, and the second chip located on the side of the second base island close to the first base island. In other words, in the height direction, the first chip and the second chip are respectively arranged on opposite sides of the two base islands. At the same time, the plastic encapsulation layer exposes the first base island and the side of the second end of the pin facing away from the first chip, and the side of the second base island facing away from the second chip, thereby forming two independent external heat dissipation interfaces located on opposite sides of the packaging structure. When the packaging structure is in operation, the heat generated by the first chip can be directly conducted outward through the first base island in contact with it, via the side of the first base island exposed by the plastic encapsulation layer; similarly, the heat generated by the second chip is conducted to the outside world through the second base island via its exposed side. Therefore, the packaging structure constructs a double-sided, three-dimensional heat dissipation channel, and heat is conducted out from two opposite sides of the packaging structure at the same time. Compared with the single-sided heat dissipation structure, the total heat dissipation area is increased, heat concentration is avoided, and the overall thermal resistance of the packaging structure is reduced. This enables the packaging structure to carry a higher power density, improves the power handling capacity of the packaging structure, reduces the impact of thermal stress on the device, and is conducive to extending the overall service life of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a flow chart of key steps in a method for forming a packaging structure according to an embodiment of the present invention;

[0046] Figures 2 to 24 It is a structural schematic diagram corresponding to the key steps in the method for forming the packaging structure of an embodiment of the present invention. DETAILED DESCRIPTION

[0047] As can be seen from the background technology, currently, the two traditional heat dissipation methods can meet the heat dissipation requirements of chips to a certain extent, but their heat dissipation has limitations.

[0048] Specifically, the traditional chip packaging heat dissipation structure has the following problems: on the one hand, most heat dissipation methods mainly dissipate heat through the bottom of the frame, which causes heat to be concentrated at the bottom of the frame. The concentration of heat sources makes the heat conduction uneven, affecting the heat dissipation effect; on the other hand, when heat dissipation is achieved by installing a heat dissipation copper sheet above the chip, which is often used in flip-chip packaging, if the chip is set on the frame by a positive bonding method, there are welding wires formed on the active surface of the chip, which has great limitations in mounting the heat dissipation copper sheet on the chip.

[0049] To solve the aforementioned technical problem, the packaging structure provided by an embodiment of the present invention is characterized by separating the first base island and the second base island and placing them at different heights, with the first chip located on the side of the first base island close to the second base island, and the second chip located on the side of the second base island close to the first base island. In other words, in terms of height, the first chip and the second chip are respectively arranged on opposite sides of the two base islands. At the same time, the plastic encapsulation layer exposes the first base island and the side of the second end of the pin facing away from the first chip, as well as the side of the second base island facing away from the second chip, thereby forming two independent external heat dissipation interfaces located on opposite sides of the packaging structure. When the packaging structure is operating, the heat generated by the first chip can be directly conducted outward through the first base island in contact with it, via the side of the first base island exposed to the plastic encapsulation layer. Similarly, the heat generated by the second chip is conducted to the outside through the second base island via its exposed side. Therefore, the packaging structure constructs a bidirectional, three-dimensional heat dissipation channel, and heat is conducted out from two opposite sides of the packaging structure at the same time. Compared with the single-sided heat dissipation structure, the total heat dissipation area is increased and the heat conduction path is shortened, avoiding heat concentration, thereby reducing the overall thermal resistance of the packaging structure. This enables the packaging structure to carry a higher power density, improves the power handling capacity of the packaging structure, reduces the impact of thermal stress on the device, and is conducive to extending the overall service life of the device.

[0050] In order to make the above-mentioned objects, features and advantages of the embodiments of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0051] Correspondingly, the present invention also provides a method for forming a packaging structure. Figure 1 is a flow chart of key steps in a method for forming a packaging structure according to an embodiment of the present invention; Figures 2 to 24 It is a structural schematic diagram corresponding to the key steps in the first embodiment of the method for forming the packaging structure of the present invention.

[0052] refer to Figures 2 to 4 , Figure 2 shows a schematic diagram of the planar structure of the lead frame, Figure 3 yes Figure 2 The cross-sectional view at AA, Figure 4 yes Figure 2 In the cross-sectional view at BB, a lead frame 100 is provided, which includes a first base island 101, a second base island 102 and pins 103 located around the first base island 101 and the second base island 102, and the pins 103 have a first end 1032 close to the first base island 101 and the second base island 102 in the horizontal direction and a second end 1033 away from the first base island 101 and the second base island 102, and the first base island 101 and the second base island 102 are spaced apart and are at different height positions.

[0053] The first base island 101 and the second base island 102 in the lead frame 100 are spaced apart and located at different heights, pre-forming a three-dimensional, double-layer chip-carrying structure for the subsequently formed package structure. This prepares for the subsequent mounting of a first chip on the side of the first base island 101 close to the second base island 102, and for the mounting of a second chip on the side of the second base island 102 close to the first base island 101. After the subsequent plastic encapsulation layer is formed, the side of the first base island 101 and the second end of the pins 103 facing away from the first chip, and the side of the second base island 102 facing away from the second chip, are simultaneously exposed from the plastic encapsulation layer, forming two independent external heat dissipation interfaces at the top and bottom of the package structure, forming a bidirectional heat dissipation channel.

[0054] It should be noted that the first base island 101 and the second base island 102 are spaced apart, specifically referring to the first base island 101 and the second base island 102 being spaced apart in the first direction X, and the first base island 101 and the second base island 102 being spaced apart in the height direction Z. Subsequently, a first chip is mounted on a side of the first base island 101 close to the second base island 102, and a second chip is mounted on a side of the second base island 102 close to the first base island 101. Specifically, in the Z direction, the first chip is mounted on a side of the first base island 101 facing the second base island 102, and the second chip is mounted on a side of the second base island 102 facing the first base island 101.

[0055] In this embodiment, the first base island 101 is used to carry and attach a first chip, and the second base island 102 is used to carry and attach a second chip.

[0056] In this embodiment, the first base island 101 and the second base island 102 are arranged along a first direction X. The lead frame 100 further includes a second direction Y, which is perpendicular to the first direction X.

[0057] In this embodiment, the pins 103 are used to electrically connect to an external circuit. In the subsequent packaging process, the pins 103 are connected to the chip, thereby establishing a signal and power path between the chip and the external circuit, thereby ensuring the electrical performance of the package structure.

[0058] In this embodiment, in the step of providing the lead frame 100 , the pin 103 includes a ground pin 103 a , a first end 1032 of the ground pin 103 a is connected to a side of the second base island 102 , and a second end 1033 of the ground pin 103 a is in the same horizontal plane as the first base island 101 .

[0059] The second end 1033 of the grounding pin 103a is on the same horizontal plane as the first base island 101, and the first end 1032 of the grounding pin 103a is connected to the side of the second base island 102 at a higher position. The first end 1032 and the second end 1033 of the grounding pin 103a have a height difference. That is to say, by utilizing the grounding pin 103a to provide physical support for the second base island 102, the second base island 102 can be in different positions relative to the first base island 101, so that the position of the second base island 102 is stable during the packaging process. Therefore, a reliable operating platform is provided for the subsequent mounting of the second chip and formation of the second lead on the second base island 102, so that the frame structure has sufficient mechanical strength, which is conducive to improving the yield and reliability of the packaging structure.

[0060] In this embodiment, in the step of providing the lead frame 100 , the ground pin 103 a and the second base island 102 are an integrated structure.

[0061] The ground pin 103a and the second base island 102 are an integrated structure, which avoids the ground pin 103a and the second base island 102 being welded or assembled as separate components, so that there is sufficient structural strength between the ground pin 103a and the second base island 102. At the same time, the manufacturing process of the lead frame 100 is simplified and the production cost is reduced. It can also obtain a continuous, interface-free electrical and thermal conduction path between the ground pin 103a and the second base island 102, which is beneficial to improving the electrical grounding performance and the thermal conduction efficiency between the second base island 102 and the ground pin 103a.

[0062] In this embodiment, in the step of providing the lead frame 100, the ground pin 103a includes an inclined portion 1031 (as shown in the black part in the figure) that is angled relative to the horizontal plane. The inclined portion 1031 is used to make the second end 1033 of the ground pin 103a and the first end 1032 of the ground pin 103a be at different height positions.

[0063] The ground pin 103a includes an inclined portion 1031 at an angle relative to a horizontal plane. The inclined portion 1031 is used to connect the first end of the ground pin 103a and the second end of the ground pin 103a at different heights in a gradual transition manner, thereby achieving the lifting of the second base island 102, avoiding stress concentration caused by the right-angle bend in the ground pin 103a, and thus helping to enhance the mechanical strength and fatigue resistance of the ground pin 103a itself, making it less likely for the lead frame 100 to break or deform during the stamping process and the subsequent packaging process, which is beneficial to improving the overall reliability and service life of the packaging structure.

[0064] In this embodiment, in the step of providing the lead frame 100, the ground pin 103a includes an inclined portion 1031 at an angle relative to a horizontal plane, and the number of inclined portions 1031 in the ground pin 103a is at least one. The number of inclined portions 1031 in the non-ground pins 103b on both sides of the second base island 102 in the second direction Y is at least one.

[0065] In this embodiment, in the step of providing the lead frame 100 , the ground pin 103 a is formed at least on a side of the second base island 102 facing away from the first base island 101 .

[0066] It should be noted that the grounding pin 103a is formed at least on the side of the second base island 102 away from the first base island 101. Specifically, the grounding pin 103a is formed at least on the side of the first base island 101 away from the second base island 102 in the first direction X. The grounding pin 103a, which plays a physical supporting role, is set on the side of the second base island 102 away from the first base island 101, thereby reserving operating space for the subsequent mounting of the first chip on the first base island 101, the mounting of the second chip on the second base island 102, and the bonding operation of the first lead and the second lead.

[0067] It should be noted that the ground pin 103a can be formed simultaneously on the side of the second base island 102 facing away from the first base island 101, and on both sides of the second base island 102 in the second direction Y. In other words, forming the ground pin 103a on three sides of the second base island 102 is conducive to providing more stable support for the second base island 102.

[0068] In this embodiment, in the step of providing the lead frame 100 , the ground pin 103 a includes at least one stepped surface structure 104 .

[0069] At least one stepped surface structure 104 is provided on ground pin 103a, thereby providing multiple bonding points of different heights for the subsequent second lead bonding to the second chip. This allows the second lead to connect to ground pin 103a via a shorter path and a more optimized arc height, reducing the risk of the second lead being washed or damaged during the plastic packaging process, improving signal transmission performance, and making the packaging structure more flexible and adaptable to different electrical connection requirements.

[0070] In this embodiment, in the step of providing the lead frame 100 , the pins 103 include non-ground pins 103 b , and the non-ground pins 103 b are spaced apart from the first base island 101 and the second base island 102 .

[0071] The non-ground pin 103b in the lead frame 100 is separated from the first base island 101 and the second base island 102. The non-ground pin 103b serves as an independent signal or power input / output port. The non-ground pin 103b is subsequently electrically connected to the first chip or the second chip through a lead, forming an electrical path between the first chip and the second chip and the external circuit, so that the subsequently formed packaging structure can achieve the predetermined function.

[0072] In this embodiment, in the step of providing the lead frame 100 , the pins 103 formed on the side of the first base island 101 away from the second base island 102 are formed in the same horizontal plane as the first base island 101 .

[0073] It should be noted that the pin 103 formed on the side of the first base island 101 away from the second base island 102 is formed in the same horizontal plane as the first base island 101. Specifically, in the first direction X, the pin 103 formed on the side of the first base island 101 away from the second base island 102 is located in the same horizontal plane as the first base island 101 in the height direction Z.

[0074] The pins 103 on the side of the first base island 101 facing away from the second base island 102 are formed in the same horizontal plane as the first base island 101, so that the pins 103 on the side of the first base island 101 facing away from the second base island 102 and the first base island 101 form a flat reference surface. Consequently, when the first chip is subsequently mounted and the first leads are formed, the entire lead frame 100 can be stably placed on a work surface, ensuring the accuracy of the second chip mounting and the first lead bonding.

[0075] In this embodiment, the step of providing the lead frame 100 includes performing a stamping process, a bending process, or a convex process on at least a portion of the lead frame 100 .

[0076] By using processing methods such as stamping, bending or convex processing, a flat metal sheet can be manufactured into a lead frame 100 with a preset three-dimensional shape, thereby forming a raised structure in which the second base island 102 and the first base island 101 are at different heights, as well as a stepped shape of the grounding pin 103a and the inclined portion 1031. Therefore, stamping, bending or convex processing of at least a portion of the lead frame 100 is a key process step to achieve the first base island 101 and the second base island 102 at different heights, which is conducive to forming a complex three-dimensional lead frame 100.

[0077] In this embodiment, in the step of providing the lead frame 100, the first base island 101 and the second base island 102 are arranged along a first direction X, the first direction X is perpendicular to the second direction Y, the first ends 1032 and the second ends 1033 of the pins 103 on the side of the second base island 102 facing away from the first base island 101 are located in different horizontal planes, and the first ends 1032 and the second ends 1033 of the pins 103 on both sides of the second base island 102 in the second direction Y are located in different horizontal planes.

[0078] In this embodiment, in the step of providing the lead frame 100, the height positions of the first ends 1032 of the pins 103 on both sides of the second base island 102 in the second direction Y are located between the first base island 101 and the second base island 102, and the second ends 1033 of the pins 103 on both sides of the second direction Y of the second base island 102 are in the same horizontal plane as the first base island 101.

[0079] The first end 1032 and the second end 1033 of the pin 103 on the side of the second base island 102 facing away from the first base island 101 are in different horizontal planes, and the first end 1032 and the second end 1033 of the pin 103 on both sides of the second direction Y of the second base island 102 are in different horizontal planes, and the height position of the first end 1032 of the pin 103 on both sides of the second direction Y of the second base island 102 is located between the first base island 101 and the second base island 102. In other words, the pins 103 around the second base island 102 are all bent, and the first end 1032 and the second end 1033 of the pins 103 are not on the same horizontal plane, so that these pins 103 can bridge different height levels, and thus these pins 103 can be connected to the first chip on the lower horizontal plane for lead connection when needed, and can also be connected to the second chip on the higher plane after the lead frame 100 is flipped over. Therefore, the same group of pins 103 can be used for lead connection between the first chip and the second chip at two different heights, so that the pin layout on the periphery of the package structure can be arranged regularly, which is conducive to simplifying the structure of the pins 103 in the lead frame 100.

[0080] like Figure 3 As shown, in the step of providing the lead frame 100, in the height direction Z perpendicular to the first base island 101 and the second base island 102, the area of ​​the surface of the first base island 101 away from the second base island 102 is smaller than the area of ​​the surface of the first base island 101 close to the second base island 102, and the area of ​​the surface of the second base island 102 away from the first base island 101 is smaller than the area of ​​the surface of the second base island 102 close to the first base island 101.

[0081] That is, the area of ​​the first base island 101 and the second base island 102 facing the outside of the lead frame 100 is smaller than the area of ​​the internal chip mounting surface, thereby forming inward-retracting slopes or steps on the sidewalls of the first base island 101 and the second base island 102. Furthermore, in the subsequent process of forming the plastic encapsulation layer, the plastic encapsulation material can better cover and lock the side edges of the first base island 101 and the second base island 102, thereby enhancing the mechanical interlocking force between the plastic encapsulation material and the first base island 101 and the second base island 102, making the bond between the first base island 101 and the second base island 102 and the plastic encapsulation layer more secure, which is conducive to preventing delamination or shedding of the packaging structure due to thermal mismatch, and improving the formation quality and service life of the packaging structure.

[0082] As an example, the first base island 101 and the second base island 102 both have a stepped block structure, and the bottom of the first base island 101 and the bottom of the second base island 102 are arranged relative to each other, that is, the side with a smaller surface area of ​​the first base island 101 turns away from the second base island 102 in the height direction Z, and the side with a smaller surface area of ​​the second base island 102 turns away from the first base island 101 in the height direction Z.

[0083] It should also be noted that the stepped block structures of the first base island 101 and the second base island 102 are formed by an etching process.

[0084] In this embodiment, the material of the lead frame 100 includes copper.

[0085] The lead frame 100 is made of copper, and by utilizing the excellent thermal conductivity and electrical conductivity of copper, the first base island 101 can quickly conduct the heat generated by the first chip to its surface away from the second base island 102, and the second base island 102 can quickly conduct the heat generated by the second chip to its surface away from the first base island 101. At the same time, the pins 103 can also transmit electrical signals with low loss, which is conducive to achieving efficient double-sided heat dissipation and reliable electrical connection, so that the packaging structure can meet the dual requirements of high-power devices for heat dissipation and electrical performance, which is conducive to improving the electrical performance of the packaging structure.

[0086] It should also be noted that, in the step of providing the lead frame 100 , connecting ribs 105 are formed on the side of the first base island 101 .

[0087] The lead frame 100 is usually processed in the form of an array, including multiple repeated structures that will become independent packaging units in the future. The connecting ribs 105 are used to connect the first base island 101 to the skeleton of the lead frame 100 or other adjacent units.

[0088] refer to Figures 5 to 7 , Figure 5 shows a schematic diagram of the planar structure of the lead frame, Figure 6 yes Figure 5 The cross-sectional view at AA, Figure 7 yes Figure 5 In the cross-sectional view at BB, in the height direction Z, the first chip 200 is mounted on the side of the first base island 101 close to the second base island 102.

[0089] The first chip 200 is mounted on the side of the first base island 101 close to the second base island 102, that is, in the height direction Z, the first chip 200 is mounted on the inner surface of the first base island 101, so that the heat generated by the first chip 200 during operation is directly transferred to the first base island 101, and the heat is guided to the side thereof away from the first chip 200 and finally exposed to the plastic packaging layer, so that the heat of the first chip 200 can be reduced.

[0090] refer to Figures 8 to 10 , Figure 8 shows a schematic diagram of the planar structure of the lead frame, Figure 9 yes Figure 8 The cross-sectional view at AA, Figure 10 yes Figure 8 In the cross-sectional view at BB, the first chip 200 is connected to at least one pin 103 around the first chip 200 through a first lead 201 .

[0091] The first chip 200 and the pin 103 are electrically interconnected through the first lead 201, thereby establishing a communication path for the first chip 200 to communicate with the external circuit, and the signal of the first chip 200 can be input or output, thereby realizing the functional integration of the first chip 200 on the lead frame 100, so that the subsequently formed packaging structure can perform its preset electronic function.

[0092] In this embodiment, a wire bonding process is used to connect the first chip 200 to the pins 103. The wire bonding process offers a high degree of process flexibility and path plasticity, enabling precise control of the lead arch height and trajectory, achieving reliable connections from the chip pads to pins 103 at any location. It can also adapt to the three-dimensional structure formed by the elevation of the second base island 102, ensuring an electrical path.

[0093] In this embodiment, during the step of forming the first leads 201, the first leads 201 connect the first chip 200 to the pins 103 on both sides of the first chip 200 in the second direction Y (specifically, to the surfaces of the first ends 1032 of the pins 103 on both sides of the second direction Y facing the second base island 102). The first leads 201 also connect the first chip 200 to the pins 103 on the side of the first base island 101 facing away from the second base island 102. In other words, the first chip 200 is connected to the pins 103 surrounding it on three sides, thereby achieving comprehensive electrical connection. The pins 103 surrounding the first base island 101 provide sufficient I / O ports for the first chip 200, facilitating optimized wiring layout and enabling signal paths to be rationally allocated according to design requirements.

[0094] It should be noted that the first lead 201 connects the first chip 200 with the pins 103 on both sides of the second direction Y of the first chip 200, specifically referring to the first end 1032 of the pins 103 on both sides of the second direction Y of the first chip 200 in the height direction Z having a first surface (not marked in the figure) close to the second base island 102, and the first lead 201 connects the first chip 200 with the first surface of the first end of the pin 103.

[0095] refer to Figures 11 to 13 , Figure 11 shows a schematic diagram of the planar structure of the lead frame, Figure 12 yes Figure 11 The cross-sectional view at AA, Figure 13 yes Figure 11 In the cross-sectional view at CC, the method for forming the packaging structure further includes: after connecting the first chip 200 to at least one pin 103 around the first chip 200 through the first lead 201, and before mounting the second chip on the second base island 102, flipping the lead frame 100.

[0096] The lead frame 100 is turned over, and the second base island 102 , which was originally facing downward, is turned upward, so as to prepare for mounting the second chip and connecting the second chip to at least one pin 103 around the second chip through the second lead 301 .

[0097] refer to Figures 14 to 16 , Figure 14 shows a schematic diagram of the planar structure of the lead frame, Figure 15 yes Figure 14 The cross-sectional view at AA, Figure 16 yes Figure 14 In the cross-sectional view at CC, in the height direction Z, the second chip 300 is mounted on the side of the second base island 102 close to the first base island 101.

[0098] The second chip 300 is mounted on the side of the second base island 102 close to the first base island 101, that is, in the height direction Z, the second chip 300 is mounted on the inner surface of the second base island 102, so that the heat generated by the second chip 300 during operation is directly transferred to the second base island 102, and the heat is guided to the side thereof away from the second chip 300 and finally exposed to the plastic packaging layer, so that the heat of the second chip 300 can be reduced.

[0099] refer to Figures 17 to 19 , Figure 17 shows a schematic diagram of the planar structure of the lead frame, Figure 18 yes Figure 17 The cross-sectional view at AA, Figure 19 yes Figure 17 In the cross-sectional view at CC, the second chip 300 is connected to at least one pin 103 around the second chip 300 through a second lead 301 .

[0100] The electrical interconnection between the second chip 300 and the pin 103 is achieved through the second lead 301, thereby establishing a communication path for the second chip 300 to communicate with the external circuit, and the signal of the second chip 300 can be input or output, thereby realizing the functional integration of the second chip 300 on the lead frame 100, so that the subsequently formed packaging structure can perform its preset electronic function.

[0101] In this embodiment, a wire bonding process is used to connect the second chip 300 to the pins 103. The wire bonding process offers a high degree of process flexibility and path plasticity, enabling precise control of the lead arch height and trajectory, achieving reliable connections from the chip pads to pins 103 at any location. It can also adapt to the three-dimensional structure formed by the elevation of the second base island 102, ensuring an electrical path.

[0102] In this embodiment, during the step of forming the second leads 301, the second leads 301 connect the second chip 300 to the pins 103 on both sides of the second chip 300 in the second direction Y. The second leads 301 also connect the second chip 300 to the pins 103 on the side of the second base island 102 facing away from the first base island 101. In other words, the second chip 300 is connected to the pins 103 surrounding it on three sides, thereby achieving comprehensive electrical connection. The pins 103 surrounding the second base island 102 provide the second chip 300 with sufficient I / O ports, facilitating optimized wiring layout and enabling signal paths to be rationally allocated according to design requirements.

[0103] It should be noted that the second lead 301 connects the second chip 300 with the pins 103 on both sides of the second direction Y of the second chip 300, specifically referring to the first end 1032 of the pins 103 on both sides of the second direction Y of the second chip 300 in the height direction Z having a second surface (not marked in the figure) close to the first base island 101, and the second lead 301 connects the second chip 300 with the second surface of the first end of the pin 103.

[0104] It should be noted that, in the step of forming the second lead 301 , the second lead 301 is connected to any one of the step surfaces of the ground pin 103 a .

[0105] The second lead 301 is connected to the stepped surface of the ground pin 103a, and bonding is performed using the flat area provided by the stepped surface, thereby ensuring the reliability of the ground connection of the second chip 300. At the same time, the stepped surface of the ground pin 103a allows the second lead 301 to connect the second chip 300 and the pin 103 in a shorter and more direct path, which can optimize the inductance of the ground path, improve the high-frequency performance, and help improve the electrical stability and signal integrity of the packaging structure.

[0106] refer to Figures 20 to 22 , Figure 20 shows a schematic diagram of the planar structure of the lead frame, Figure 21 yes Figure 20 The cross-sectional view at AA, Figure 22 yes Figure 20 In the cross-sectional view at CC, a plastic encapsulation layer 400 is formed on the lead frame 100 to encapsulate the first chip 200, the second chip 300, the first lead 201 and the second lead 301. In the height direction Z, the plastic encapsulation layer 400 exposes the first base island 101 and the side of the second end of the pin 103 facing away from the first chip 200, and the side of the second base island 102 facing away from the second chip 300.

[0107] In the method for forming a packaging structure provided by an embodiment of the present invention, the first base island 101 and the second base island 102 are separated and located at different heights, and the first chip 200 is located on the side of the first base island 101 close to the second base island 102, and the second chip 300 is located on the side of the second base island 102 close to the first base island 101. In other words, the first chip 200 and the second chip 300 are respectively arranged on opposite sides of the two base islands. At the same time, in the height direction Z, the plastic encapsulation layer 400 exposes the side of the first base island 101 facing away from the first chip 200, the side of the second base island 102 facing away from the second chip 300, and the side of the second end 1033 of the pin 103 facing away from the first chip 200, thereby forming two independent external heat dissipation interfaces located on opposite sides of the packaging structure. When the package structure is operating, the heat generated by the first chip 200 can be directly conducted outward through the first base island 101 in contact with it, via the side of the first base island 101 exposed from the plastic encapsulation layer 400. Similarly, the heat generated by the second chip 300 is conducted to the outside world through the second base island 102 via its exposed side. Therefore, the package structure creates a double-sided, three-dimensional heat dissipation channel, and heat is simultaneously conducted from two opposing sides of the package structure. Compared to a single-sided heat dissipation structure 600, this increases the total heat dissipation area, avoids heat concentration, and thus reduces the overall thermal resistance of the package structure. This enables the package structure to carry a higher power density, improves the power handling capability of the package structure, reduces the impact of thermal stress on the device, and helps extend the overall service life of the device.

[0108] In this embodiment, the step of performing plastic encapsulation on the lead frame 100 to form a plastic encapsulation layer 400 includes: forming a first protective film 106 on the lead frame 100 in the height direction Z on the side of the first base island 101 facing away from the first chip 200, and on the side of the second end 1033 of the pin 103 facing away from the first chip 200; forming a second protective film 107 on the lead frame 100 in the height direction Z on the side of the second base island 102 facing away from the second chip, and making the pin 103 located between the first protective film 106 and the second protective film 107; injecting a plastic encapsulation material between the first protective film 106 and the second protective film 107, the plastic encapsulation material encapsulating the first chip 200, the second chip 300, the first lead 201, the second lead 301 and the pin 103; and curing the plastic encapsulation material to form the plastic encapsulation layer 400.

[0109] A first protective film 106 is formed on the side of the first base island 101 facing away from the first chip 200, and on the side of the second end 1033 of the pin 103 facing away from the first chip 200; a second protective film 107 is formed on the side of the second base island 102 facing away from the second chip. That is, in the height direction Z, the first protective film 106 and the second protective film 107 are respectively attached to both sides of the lead frame 100 to precisely define the molding area. This prevents molding compound from overflowing onto the surfaces of the first and second base islands 101 and 102 that need to be exposed during injection molding. This ensures that the heat dissipation surfaces of the first and second base islands 101 and 102, as well as the side of the second end 1033 of the pin 103 facing away from the first chip 200, remain clean and fully exposed after molding. This allows for reliable molding of the double-sided heat dissipation structure 600, which helps ensure the consistency and performance of the final product.

[0110] It should be noted that, in some embodiments, the method for forming the packaging structure further includes: after forming the plastic encapsulation layer, removing the first protective film 106 and the second protective film 107, so that the first base island 101 and the second end 1033 of the pin 103 are away from the side of the first chip 200 and the side of the second base island 102 is away from the second chip 300 are exposed.

[0111] refer to Figure 23 and Figure 24 , Figure 24 yes Figure 23 In the cross-sectional view at AA, the method for forming the packaging structure further includes: after performing plastic sealing on the lead frame 100 to form a plastic sealing layer 400, attaching the first base island 101 and the second end 1033 of the pin 103 away from the first chip 200 on the substrate 500; after performing plastic sealing on the lead frame 100 to form a plastic sealing layer 400, forming a heat dissipation structure 600 on the side of the second base island 102 away from the second chip 300.

[0112] The first base island 101 and the second end 1033 of the pin 103 are attached to the substrate 500 on the side facing away from the first chip 200, and the heat dissipation structure 600 is formed on the side of the second base island 102 facing away from the second chip 300, thereby integrating the packaging structure into a complete heat dissipation system. Furthermore, heat can be conducted to the substrate 500 through the heat dissipation surface of the first base island 101 facing the substrate 500, while the heat can be efficiently dissipated into the heat dissipation structure 600 through the heat dissipation surface of the second base island 102 facing the heat dissipation structure 600, and dissipated through the heat dissipation structure 600. Therefore, the packaging structure utilizes the potential for double-sided heat dissipation, allowing the packaging structure to maintain a lower temperature under high-power conditions, thereby reducing the overall thermal resistance of the packaging structure. This enables the packaging structure to carry a higher power density, improves the power handling capability of the packaging structure, reduces the impact of thermal stress on the device, and helps to extend the overall service life of the device.

[0113] It should also be noted that, in the step of attaching the substrate 500 , the second end 1033 of the ground pin 103 a and the non-ground pin 103 b are connected to the substrate 500 .

[0114] The embodiment of the present invention also provides a packaging structure, referring to Figure 23 and Figure 24 , which illustrates a schematic structural diagram of the packaging structure of an embodiment of the present invention.

[0115] The package structure includes: a lead frame 100, the lead frame 100 includes a first base island 101, a second base island 102, and a pin 103 located around the first base island 101 and the second base island 102, the pin 103 having a first end 1032 close to the first base island 101 and the second base island 102 in the horizontal direction and a second end 1033 away from the first base island 101 and the second base island 102, the first base island 101 and the second base island 102 are spaced apart and at different heights; a first chip 200 is located on a side of the first base island 101 close to the second base island 102 in the height direction Z; a first lead 201 connects the first chip 200 to the surrounding area of ​​the first chip 200 at least one pin 103 is connected; a second chip 300 is located on the side of the second base island 102 close to the first base island 101 in the height direction Z; a second lead 301 connects the second chip 300 to at least one pin 103 around the second chip 300; a plastic layer 400 is located on the lead frame 100, the plastic layer 400 encapsulates the first chip 200, the second chip 300, the first lead 201 and the second lead 301, and the plastic layer 400 exposes the first base island 101 and the second end 1033 of the pin 103 in the height direction Z away from the first chip 200 and the side of the second base island 102 away from the second chip 300.

[0116] In the package structure provided by an embodiment of the present invention, in the horizontal direction, the first base island 101 and the second base island 102 are spaced apart and located at different heights. In the height direction Z, the first chip 200 is located on the side of the first base island 101 close to the second base island 102, and the second chip 300 is located on the side of the second base island 102 close to the first base island 101. In other words, in the height direction Z, the first chip 200 and the second chip 300 are respectively arranged on opposite sides of the two base islands. At the same time, the plastic encapsulation layer 400 exposes the first base island 101 and the second end of the pin 103 facing away from the first chip 200, and the side of the second base island 102 facing away from the second chip 300, forming two independent external heat dissipation interfaces located on opposite sides of the package structure. When the package structure is in operation, heat generated by the first chip 200 can be directly transferred outward through the first base island 101 in contact with it, via the side of the first base island 101 exposed by the plastic encapsulation layer 400. Similarly, heat generated by the second chip 300 is transferred to the outside through the second base island 102 via its exposed side. Therefore, the packaging structure constructs a double-sided, three-dimensional heat dissipation channel, and heat is conducted out from two opposite sides of the packaging structure at the same time. Compared with the single-sided heat dissipation structure 600, the total heat dissipation area is increased, heat concentration is avoided, and the overall thermal resistance of the packaging structure is reduced. This enables the packaging structure to carry a higher power density, improves the power processing capability of the packaging structure, reduces the impact of thermal stress on the device, and is conducive to extending the overall service life of the device.

[0117] In this embodiment, the lead frame 100 includes a first base island 101, a second base island 102, and a pin 103 located around the first base island 101 and the second base island 102. The pin 103 has a first end 1032 close to the first base island 101 and the second base island 102 in the horizontal direction and a second end 1033 away from the first base island 101 and the second base island 102. The first base island 101 and the second base island 102 are spaced apart and are at different heights.

[0118] In the height direction Z, the first base island 101 and the second base island 102 in the lead frame 100 are spaced apart so that the first base island 101 and the second base island 102 are at different heights, providing a three-dimensional, double-layer chip-carrying structure for the package structure. This allows the first chip 200 to be disposed on a side of the first base island 101 close to the second base island 102, and the second chip 300 to be disposed on a side of the second base island 102 close to the first base island 101. After the subsequent formation of the plastic encapsulation layer 400, the side of the first base island 101 and the second end 1033 of the pin 103 facing away from the first chip 200, as well as the side of the second base island 102 facing away from the second chip 300, are simultaneously exposed to the plastic encapsulation layer 400. This allows the package structure to form two independent external heat dissipation interfaces at the top and bottom, forming a bidirectional heat dissipation channel.

[0119] It should be noted that the first base island 101 and the second base island 102 are spaced apart, which specifically means that the first base island 101 and the second base island 102 are spaced apart in the first direction X, and the first base island 101 and the second base island 102 are spaced apart in the height direction Z.

[0120] In this embodiment, the first base island 101 and the second base island 102 are arranged along a first direction X. The lead frame 100 further includes a second direction Y, which is perpendicular to the first direction X.

[0121] In this embodiment, the pins 103 are used to electrically connect to an external circuit, forming a signal and power path between the chip and the external circuit, thereby ensuring the electrical performance of the package structure.

[0122] In this embodiment, the pin 103 includes a ground pin 103 a , a first end 1032 of the ground pin 103 a is connected to a side of the second base island 102 , and a second end 1033 of the ground pin 103 a is in the same horizontal plane as the first base island 101 .

[0123] The second end 1033 of the grounding pin 103a is at the same horizontal plane as the first base island 101, and the first end 1032 of the grounding pin 103a is connected to the side of the second base island 102 at a higher position. There is a height difference between the first end 1032 and the second end 1033 of the grounding pin 103a. That is to say, by utilizing the grounding pin 103a to provide physical support for the second base island 102, the second base island 102 can be in different positions relative to the first base island 101, so that the second base island 102 has a stable support in the packaging structure, providing stable support for the second chip 300.

[0124] In this embodiment, the ground pin 103 a and the second base island 102 are an integrated structure.

[0125] The ground pin 103a and the second base island 102 are an integrated structure, which avoids the ground pin 103a and the second base island 102 being welded or assembled as separate components, so that there is sufficient structural strength between the ground pin 103a and the second base island 102. At the same time, the manufacturing process of the lead frame 100 is simplified and the production cost is reduced. It can also obtain a continuous, interface-free electrical and thermal conduction path between the ground pin 103a and the second base island 102, which is beneficial to improving the electrical grounding performance and the thermal conduction efficiency between the second base island 102 and the ground pin 103a.

[0126] In this embodiment, the ground pin 103a includes an inclined portion 1031 at an angle relative to a horizontal plane. The inclined portion 1031 is used to position the second end 1033 of the ground pin 103a and the first end 1032 of the ground pin 103a at different heights.

[0127] The ground pin 103a includes an inclined portion 1031 at an angle relative to a horizontal plane. The inclined portion 1031 is used to connect the first end of the ground pin 103a and the second end of the ground pin 103a at different heights in a gradual transition manner, thereby achieving the lifting of the second base island 102, avoiding stress concentration caused by the right-angle bend in the ground pin 103a, and thus helping to enhance the mechanical strength and fatigue resistance of the ground pin 103a itself, making it less likely for the lead frame 100 to break or deform in the packaging structure, which is beneficial to improving the overall reliability and service life of the packaging structure.

[0128] In this embodiment, the ground pin 103a includes an inclined portion 1031 at an angle relative to a horizontal plane, and the ground pin 103a has at least one inclined portion 1031. The non-ground pins 103b on both sides of the second base island 102 in the second direction Y have at least one inclined portion 1031.

[0129] In this embodiment, the ground pin 103 a is at least located on a side of the second base island 102 away from the first base island 101 .

[0130] The ground pin 103a, which serves as a physical support, is arranged on the side of the second base island 102 away from the first base island 101, thereby reserving operating space for preparing for mounting the first chip 200 on the first base island 101 and mounting the second chip 300 on the second base island 102 during the formation of the packaging structure, as well as for forming the first lead 201 and the second lead 301.

[0131] It should be noted that the ground pin 103a can be formed simultaneously on the side of the second base island 102 facing away from the first base island 101, and on both sides of the second base island 102 in the second direction Y. In other words, forming the ground pin 103a on three sides of the second base island 102 is conducive to providing more stable support for the second base island 102.

[0132] In this embodiment, the ground pin 103 a includes at least one stepped surface structure 104 .

[0133] At least one step surface structure 104 is provided on the ground pin 103a, thereby providing a plurality of bonding points of different heights for bonding the second lead 301 bonded to the second chip 300, thereby allowing the second lead 301 to be connected to the ground pin 103a with a shorter path and a more optimized arc height, thereby reducing the risk of the second lead 301 being washed away or damaged during the formation of the plastic layer 400, improving the signal transmission performance, and making the packaging structure more flexible and adaptable to different electrical connection requirements.

[0134] In this embodiment, the pins 103 include non-ground pins 103 b , and the non-ground pins 103 b are spaced apart from the first base island 101 and the second base island 102 .

[0135] The non-ground pin 103b in the lead frame 100 is separated from the first base island 101 and the second base island 102. The non-ground pin 103b serves as an independent signal or power input / output port. The non-ground pin 103b is subsequently electrically connected to the first chip 200 or the second chip 300 through a lead, forming an electrical path between the first chip 200 and the second chip 300 and the external circuit, so that the subsequently formed packaging structure can achieve the predetermined function.

[0136] In this embodiment, the pins 103 located on the side of the first base island 101 away from the second base island 102 are formed in the same horizontal plane as the first base island 101 .

[0137] The pins 103 located on the side of the first base island 101 facing away from the second base island 102 are formed in the same horizontal plane as the first base island 101. Thus, the pins 103 on the side of the first base island 101 facing away from the second base island 102 form a flat reference surface with the first base island 101. Furthermore, when mounting the first chip 200 and forming the first leads 201, the entire lead frame 100 can be stably placed on a work surface, ensuring the accuracy of mounting the second chip 300 and bonding the first leads 201.

[0138] In this embodiment, the first base island 101 and the second base island 102 are arranged along a first direction X, which is perpendicular to the second direction Y. The first ends 1032 and the second ends 1033 of the pins 103 on the side of the second base island 102 facing away from the first base island 101 are located in different horizontal planes, and the first ends 1032 and the second ends 1033 of the pins 103 on both sides of the second base island 102 in the second direction Y are located in different horizontal planes.

[0139] In this embodiment, the height positions of the first ends 1032 of the pins 103 on both sides of the second base island 102 in the second direction Y are located between the first base island 101 and the second base island 102, and the second ends 1033 of the pins 103 on both sides of the second base island 102 in the second direction Y are in the same horizontal plane as the first base island 101.

[0140] The first end 1032 and the second end 1033 of the pin 103 on the side of the second base island 102 facing away from the first base island 101 are in different horizontal planes, and the first end 1032 and the second end 1033 of the pin 103 on both sides of the second direction Y of the second base island 102 are in different horizontal planes, and the height position of the first end 1032 of the pin 103 on both sides of the second direction Y of the second base island 102 is located between the first base island 101 and the second base island 102. In other words, the pins 103 around the second base island 102 are all bent, and the first end 1032 and the second end 1033 of the pins 103 are not on the same horizontal plane, so that these pins 103 can jump across different height levels, and then these pins 103 can be connected to the first chip 200 on a lower horizontal plane for lead connection when needed, and can also be connected to the second chip 300 on a higher plane for lead connection. Therefore, the same group of pins 103 can be used for lead connection of the first chip 200 and the second chip 300 at two different heights, so that the pin layout on the periphery of the packaging structure can be arranged regularly, which is conducive to simplifying the structure of the pins 103 in the lead frame 100.

[0141] In this embodiment, in the height direction Z (eg, perpendicular to the first base island 101 and the second base island 102), Figure 3 As shown), the area of ​​the surface of the first base island 101 facing away from the second base island 102 is smaller than the area of ​​the surface of the first base island 101 close to the second base island 102, and the area of ​​the surface of the second base island 102 facing away from the first base island 101 is smaller than the area of ​​the surface of the second base island 102 close to the first base island 101.

[0142] That is, the area of ​​the first base island 101 and the second base island 102 facing the outside of the lead frame 100 is configured to be smaller than the area of ​​the internal chip mounting surface, thereby forming inward-retracting slopes or steps on the sidewalls of the first base island 101 and the second base island 102. Furthermore, the plastic encapsulation layer 400 can better cover and lock the side edges of the first base island 101 and the second base island 102, thereby enhancing the mechanical interlocking force between the plastic encapsulation material and the first base island 101 and the second base island 102, making the bond between the first base island 101 and the second base island 102 and the plastic encapsulation layer 400 more secure, which helps prevent delamination or shedding of the package structure due to thermal mismatch, thereby improving the formation quality and service life of the package structure.

[0143] As an example, the first base island 101 and the second base island 102 both have a stepped block structure, and the bottom of the first base island 101 and the bottom of the second base island 102 are arranged relative to each other, that is, the side with a smaller surface area of ​​the first base island 101 faces away from the second base island 102, and the side with a smaller surface area of ​​the second base island 102 faces away from the first base island 101.

[0144] In this embodiment, the material of the lead frame 100 includes copper.

[0145] The lead frame 100 is made of copper, and by utilizing the excellent thermal conductivity and electrical conductivity of copper, the first base island 101 can quickly conduct the heat generated by the first chip 200 to its surface away from the second base island 102, and the second base island 102 can quickly conduct the heat generated by the second chip 300 to its surface away from the first base island 101. At the same time, the pins 103 can also transmit electrical signals with low loss, which is conducive to achieving efficient double-sided heat dissipation and reliable electrical connection, so that the packaging structure can meet the dual requirements of high-power devices for heat dissipation and electrical performance, which is conducive to improving the electrical performance of the packaging structure.

[0146] It should also be noted that the side of the first base island 101 is formed with connecting ribs 105 .

[0147] In this embodiment, the first chip 200 is located on a side of the first base island 101 close to the second base island 102 .

[0148] The first chip 200 is mounted on the inner surface of the first base island 101, so that the heat generated during the operation of the first chip 200 is directly transferred to the first base island 101, and the heat is guided to the side away from the first chip 200 and finally exposed to the plastic layer 400, so that the heat of the first chip 200 can be reduced.

[0149] In this embodiment, the first lead 201 connects the first chip 200 to at least one pin 103 around the first chip 200 .

[0150] The first chip 200 and the pin 103 are electrically interconnected through the first lead 201, thereby establishing a communication path for the first chip 200 to communicate with the external circuit, and the signal of the first chip 200 can be input or output, thereby realizing the functional integration of the first chip 200 on the lead frame 100, so that the subsequently formed packaging structure can perform its preset electronic function.

[0151] In this embodiment, the first leads 201 connect the first chip 200 to the pins 103 on both sides of the first chip 200 in the second direction Y. The first leads 201 also connect the first chip 200 to the pins 103 on the side of the first base island 101 facing away from the second base island 102. In other words, the first chip 200 is connected to the pins 103 surrounding it on three sides, thus achieving comprehensive electrical connection. The pins 103 surrounding the first base island 101 provide the first chip 200 with sufficient I / O ports, which facilitates optimized wiring layout and allows signal paths to be rationally allocated according to design requirements.

[0152] It should be noted that the first lead 201 connects the first chip 200 with the pins 103 on both sides of the second direction Y of the first chip 200, specifically referring to the first end 1032 of the pins 103 on both sides of the second direction Y of the first chip 200 in the height direction Z having a first surface (not marked in the figure) close to the second base island 102, and the first lead 201 connects the first chip 200 with the first surface of the first end 1032 of the pin 103.

[0153] In this embodiment, the second chip 300 is located on a side of the second base island 102 close to the first base island 101 .

[0154] The second chip 300 is mounted on the side of the second base island 102 close to the first base island 101, that is, the second chip 300 is mounted on the inner surface of the second base island 102, so that the heat generated by the second chip 300 during operation is directly transferred to the second base island 102, and the heat is guided to the side thereof away from the second chip 300 and finally exposed to the plastic packaging layer 400, so that the heat of the second chip 300 can be reduced.

[0155] In this embodiment, the second lead 301 connects the second chip 300 to at least one pin 103 around the second chip 300 .

[0156] The electrical interconnection between the second chip 300 and the pin 103 is achieved through the second lead 301, thereby establishing a communication path for the second chip 300 to communicate with the external circuit, and the signal of the second chip 300 can be input or output, thereby realizing the functional integration of the second chip 300 on the lead frame 100, so that the subsequently formed packaging structure can perform its preset electronic function.

[0157] In this embodiment, the second leads 301 connect the second chip 300 to the pins 103 on both sides of the second chip 300 in the second direction Y. The second leads 301 also connect the second chip 300 to the pins 103 on the side of the second base island 102 facing away from the first base island 101. In other words, the second chip 300 is connected to the pins 103 surrounding it on three sides, thus achieving comprehensive electrical connection. The pins 103 surrounding the second base island 102 provide sufficient I / O ports for the second chip 300, facilitating optimized wiring layout and enabling signal paths to be rationally allocated according to design requirements.

[0158] It should be noted that the second leads 301 connect the second chip 300 to the pins 103 on both sides of the second chip 300 in the second direction Y. Specifically, in the height direction Z, the first ends 1032 of the pins 103 on both sides of the second chip 300 in the second direction Y have a second surface (not shown) close to the first base island 101. The second leads 301 connect the second chip 300 to the second surface of the first ends 1032 of the pins 103. It should be noted that the second leads 301 are connected to the stepped surface of the ground pin 103a.

[0159] The second lead 301 is connected to the stepped surface of the ground pin 103a, and bonding is performed using the flat area provided by the stepped surface, thereby ensuring the reliability of the ground connection of the second chip 300. At the same time, the stepped surface of the ground pin 103a allows the second lead 301 to connect the second chip 300 and the pin 103 in a shorter and more direct path, which can optimize the inductance of the ground path, improve the high-frequency performance, and help improve the electrical stability and signal integrity of the packaging structure.

[0160] In this embodiment, the plastic encapsulation layer 400 is located on the lead frame 100 , and the plastic encapsulation layer 400 exposes the first base island 101 and the second end of the pin 103 facing away from the first chip 200 and the second base island 102 facing away from the second chip 300 in the height direction Z.

[0161] When the packaging structure provided by the embodiment of the present invention is in operation, the heat generated by the first chip 200 can be directly conducted outward through the first base island 101 in contact with it, via the side of the first base island 101 that is exposed to the plastic encapsulation layer 400; similarly, the heat generated by the second chip 300 is conducted to the outside world through the second base island 102 via the exposed side thereof. Therefore, the packaging structure constructs a double-sided, three-dimensional heat dissipation channel, and heat is simultaneously conducted out from two opposing sides of the packaging structure. Compared with the single-sided heat dissipation structure 600, the total heat dissipation area is increased, heat concentration is avoided, and the overall thermal resistance of the packaging structure is reduced. This enables the packaging structure to carry a higher power density, improves the power handling capability of the packaging structure, reduces the impact of thermal stress on the device, and helps to extend the overall service life of the device.

[0162] In this embodiment of the present invention, the plastic encapsulation layer 400 exposes the second end 1033 of the pin 103 facing away from the first chip 200 in the height direction Z. The pin 103 is used to electrically connect to an external circuit. During the subsequent packaging process, the pin 103 is connected to the chip, thereby establishing a signal and power path between the chip and the external circuit.

[0163] The packaging structure further includes: a substrate 500 located on a side of the first base island 101 away from the first chip 200 ; and a heat dissipation structure 600 located on a side of the second base island 102 away from the second chip 300 .

[0164] The first base island 101 and the second end 1033 of the pin 103 are attached to the substrate 500 on the side facing away from the first chip 200, and the second base island 102 forms a heat dissipation structure 600 on the side facing away from the second chip 300, thereby integrating the package structure into a complete heat dissipation system. Furthermore, heat can be conducted to the substrate 500 through the heat dissipation surface of the first base island 101 facing the substrate 500, while the heat can be efficiently dissipated to the heat dissipation structure 600 through the heat dissipation surface of the second base island 102 facing the heat dissipation structure 600 and dissipated through the heat dissipation structure 600. Therefore, the package structure maximizes the potential of double-sided heat dissipation, allowing the package structure to maintain a lower temperature under high-power conditions, thereby reducing the overall thermal resistance of the package structure. This enables the package structure to carry a higher power density, improves the power handling capability of the package structure, reduces the impact of thermal stress on the device, and helps to extend the overall service life of the device.

[0165] It should also be noted that the second end 1033 of the ground pin 103 a and the non-ground pin 103 b are connected to the substrate 500 .

[0166] The packaging structure can be formed by the forming method described in the above embodiment, or by other forming methods. For the detailed description of the packaging structure described in this embodiment, reference can be made to the corresponding description in the above embodiment, and this embodiment will not be repeated here.

[0167] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A packaging structure, characterized in that: include: A lead frame comprising a first base island, a second base island, and pins located around the first and second base islands, the pins having a first end horizontally close to the first and second base islands and a second end remote from the first and second base islands, the first and second base islands being spaced apart and at different heights; A first chip is located on a side of the first base island close to the second base island in the height direction; a first lead connecting the first chip to at least one pin around the first chip; a second chip, located on a side of the second base island close to the first base island in the height direction; a second lead connecting the second chip to at least one pin around the second chip; A plastic encapsulation layer is located on the lead frame, and the plastic encapsulation layer encapsulates the first chip, the second chip, the first lead and the second lead, and the plastic encapsulation layer exposes the first base island and the second end of the pin facing away from the first chip and the side of the second base island facing away from the second chip in the height direction.

2. The packaging structure according to claim 1, wherein: The pins include a ground pin, a first end of the ground pin is connected to a side of the second base island, and a second end of the ground pin is in the same horizontal plane as the first base island.

3. The packaging structure according to claim 2, wherein: The ground pin and the second base island are an integrated structure.

4. The packaging structure according to claim 2, wherein: The ground pin includes an inclined portion that is angled relative to a horizontal plane, and the inclined portion is used to enable the second end of the ground pin and the first end of the ground pin to be at different heights.

5. The packaging structure according to claim 2, wherein: The ground pin is at least located on a side of the second base island facing away from the first base island.

6. The packaging structure according to claim 2, wherein: The ground pin includes at least one stepped surface structure.

7. The packaging structure according to claim 6, wherein: The second lead is connected to any one of the step surfaces of the ground pin.

8. The packaging structure according to claim 1, wherein: The first base island and the second base island are arranged along a first direction, the first direction is perpendicular to the second direction, the first end and the second end of the pin on the side of the second base island away from the first base island are in different horizontal planes, and the first end and the second end of the pin on both sides of the second direction of the second base island are in different horizontal planes.

9. The packaging structure according to claim 1, wherein: The height positions of the first ends of the pins on both sides of the second base island in the second direction are located between the first base island and the second base island, and the second ends of the pins on both sides of the second base island in the second direction are in the same horizontal plane as the first base island.

10. The packaging structure according to claim 1, wherein: The pins include non-ground pins, and the non-ground pins are spaced apart from the first base island and the second base island.

11. The packaging structure according to claim 1, wherein: The pin located on a side of the first base island away from the second base island is formed in the same horizontal plane as the first base island.

12. The packaging structure according to claim 8, wherein: The first base islands and the second base islands are arranged along a first direction, and the first direction is perpendicular to the second direction; The first lead connects the first chip to the pins on both sides of the first chip in the second direction, and further connects the first chip to the pins on a side of the first base island away from the second base island.

13. The packaging structure according to claim 8, wherein: The first base islands and the second base islands are arranged along a first direction, and the first direction is perpendicular to the second direction; The second lead connects the second chip to the pins on both sides of the second chip in the second direction, and further connects the second chip to the pins on a side of the second base island away from the first base island.

14. The packaging structure according to claim 1, wherein: In the height direction perpendicular to the first base island and the second base island, the area of ​​the surface of the first base island facing away from the second base island is smaller than the area of ​​the surface of the first base island close to the second base island, and the area of ​​the surface of the second base island facing away from the first base island is smaller than the area of ​​the surface of the second base island close to the first base island.

15. The packaging structure according to claim 1, wherein: The first base island and the second base island both have a stepped block structure, and the bottom of the first base island and the bottom of the second base island are arranged opposite to each other.

16. The packaging structure according to claim 1, wherein: The packaging structure further includes: a substrate, located on a side of the first base island facing away from the first chip; The heat dissipation structure is located on a side of the second base island facing away from the second chip.

17. The packaging structure according to claim 1, wherein: The material of the lead frame includes copper.

18. A method for forming a packaging structure, characterized in that: include: A lead frame is provided, comprising a first base island, a second base island, and pins located around the first base island and the second base island, wherein the pins have a first end horizontally close to the first base island and the second base island and a second end remote from the first base island and the second base island, and the first base island and the second base island are spaced apart and located at different heights; In the height direction, mounting a first chip on a side of the first base island close to the second base island; connecting the first chip to at least one pin around the first chip through a first lead; In the height direction, mounting a second chip on a side of the second base island close to the first base island; connecting the second chip to at least one pin around the second chip through a second lead; Plastic encapsulation is performed on the lead frame to form a plastic encapsulation layer to encapsulate the first chip, the second chip, the first lead and the second lead, and the plastic encapsulation layer exposes the first base island and the side of the second end of the pin facing away from the first chip and the side of the second base island facing away from the second chip in the height direction.

19. The method according to claim 18, wherein In the step of providing the lead frame, the pins include a ground pin, a first end of the ground pin is connected to a side of the second base island, and a second end of the ground pin is in the same horizontal plane as the first base island.

20. The method according to claim 19, wherein In the step of providing a lead frame, the ground pin and the second base island are an integral structure.

21. The method according to claim 19, wherein In the step of providing the lead frame, the ground pin includes an inclined portion that is angled relative to a horizontal plane, and the inclined portion is used to enable the second end of the ground pin and the first end of the ground pin to be at different heights.

22. The method of claim 19, wherein: In the step of providing a lead frame, the ground pin is formed at least on a side of the second base island facing away from the first base island.

23. The method of claim 19, wherein: In the step of providing a lead frame, the ground pin includes at least one stepped surface structure.

24. The method according to claim 23, wherein In the step of forming the second lead, the second lead is connected to any one of the step surfaces of the ground pin.

25. The method of claim 18, wherein: In the step of providing a lead frame, the first base island and the second base island are arranged along a first direction, the first direction is perpendicular to the second direction, the first end and the second end of the pin on the side of the second base island away from the first base island are in different horizontal planes, and the first end and the second end of the pin on both sides of the second base island in the second direction are in different horizontal planes.

26. The method of claim 25, wherein: In the step of providing a lead frame, the height positions of the first ends of the pins on both sides of the second base island in the second direction are located between the first base island and the second base island, and the second ends of the pins on both sides of the second base island in the second direction are in the same horizontal plane as the first base island.

27. The method of claim 18, wherein: In the step of providing a lead frame, the pins include non-ground pins, and the non-ground pins are spaced apart from the first base island and the second base island.

28. The method of claim 18, wherein: In the step of providing the lead frame, the pins formed on the side of the first base island facing away from the second base island are formed in the same horizontal plane as the first base island.

29. The method of claim 18, wherein The step of providing a lead frame includes performing a stamping process, a bending process, or a convex process on at least a portion of the lead frame.

30. The method of claim 18, wherein The method for forming the packaging structure further includes: after connecting the first chip to at least one pin around the first chip through a first lead and before mounting the second chip on the second base island, flipping the lead frame.

31. The method of claim 25, wherein: In the step of providing the lead frame, the first base island and the second base island are arranged along a first direction, and the first direction is perpendicular to the second direction; In the step of forming the first leads, the first leads connect the first chip to the pins on both sides of the first chip in the second direction, and also connect the first chip to the pins on the side of the first base island away from the second base island.

32. The method of claim 25, wherein: In the step of providing the lead frame, the first base island and the second base island are arranged along a first direction, and the first direction is perpendicular to the second direction; In the step of forming the second leads, the second leads connect the second chip to the pins on both sides of the second chip in the second direction, and also connect the second chip to the pins on the side of the second base island away from the first base island.

33. The method of claim 18, wherein In the step of providing a lead frame, in the height direction perpendicular to the first base island and the second base island, the area of ​​the surface of the first base island facing away from the second base island is smaller than the area of ​​the surface of the first base island close to the second base island, and the area of ​​the surface of the second base island facing away from the first base island is smaller than the area of ​​the surface of the second base island close to the first base island.

34. The method of claim 18, wherein In the step of providing the lead frame, the first base island and the second base island both have a stepped block structure, and the bottom of the first base island and the bottom of the second base island are arranged opposite to each other.

35. The method of claim 18, wherein The step of performing plastic encapsulation on the lead frame to form a plastic encapsulation layer comprises: On the lead frame, a first protective film is formed on a side of the first base island facing away from the first chip, and on a side of the second end of the pin facing away from the first chip; On the lead frame, a second protective film is formed on a side of the second base island facing away from the second chip, and the pins are located between the first protective film and the second protective film; Injecting a molding material between the first protective film and the second protective film, wherein the molding material encapsulates the first chip, the second chip, the first lead, the second lead, and the pin; curing the molding material to form the molding layer; The method for forming the packaging structure further includes: after forming the plastic encapsulation layer, removing the first protective film and the second protective film to expose the first base island and the second end of the pin facing away from the first chip and the second base island facing away from the second chip.

36. The method of claim 18, wherein The method for forming the package structure further comprises: after performing plastic encapsulation on the lead frame to form a plastic encapsulation layer, attaching the first base island and the second end of the pin on a side facing away from the first chip to a substrate; After performing plastic packaging on the lead frame to form a plastic packaging layer, a heat dissipation structure is formed on a side of the second base island facing away from the second chip.

37. The method of claim 18, wherein The material of the lead frame includes copper.

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