Stacked crystal type optocoupler packaging structure and packaging method thereof

Abstract

The invention belongs to the technical field of electrical components, and particularly relates to a stacked crystal type optocoupler packaging structure and a packaging method thereof.The stacked crystal type optocoupler packaging structure comprises an LED chip and a photosensitive chip; the LED chip is arranged above the photosensitive chip, and an isolation mechanism is arranged between the LED chip and the photosensitive chip; the isolation mechanism comprises an isolation film and a heat conduction assembly. The isolation film is arranged between the LED chip and the photosensitive chip; the heat conduction assemblies are arranged on the upper and lower surfaces of the isolation rubber sheet and are in contact with the upper and lower surfaces of the isolation rubber sheet, and the heat conduction assemblies uniformly transfer heat to the upper and lower surfaces of the isolation rubber sheet, so that when the isolation rubber sheet is heated and cured, the heat can be uniformly transferred to the isolation rubber sheet through the heat conduction assemblies; the isolation film is heated uniformly, and layering of the isolation film is avoided. And effective heat dissipation is carried out on the chip during application, so that the product has better heat effect parameters.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrical components, specifically to the technical field of devices composed of multiple semiconductor or other solid-state components formed in or on a common substrate, and particularly relates to a stacked optocoupler package structure and a packaging method thereof. Background Art

[0002] In a stacked optocoupler package structure arranged in a stacked structure, an isolation film is provided between the internal photosensitive chip and the LED chip. However, since the LED chip and the photosensitive chip are provided above and below the isolation film, delamination occurs during the heat curing of the isolation film, resulting in deviation of red light propagation.

[0003] Therefore, due to the technical problem of delamination during the heat curing of the isolation film in the stacked optocoupler package structure arranged in a stacked structure, a stacked optocoupler package structure and a packaging method thereof need to be designed.

[0004] It should be noted that the above information disclosed in this background art section is only used to understand the background art of the concept of this application. Therefore, the above description is not considered as information of the prior art. Summary of the Invention

[0005] The embodiments of the present disclosure at least provide a stacked optocoupler package structure and a packaging method thereof.

[0006] In a first aspect, the embodiments of the present disclosure provide a stacked optocoupler package structure, including: An LED chip and a photosensitive chip; The LED chip is disposed above the photosensitive chip, and an isolation mechanism is disposed between the LED chip and the photosensitive chip; wherein The isolation mechanism includes: an isolation film and a heat conduction component; The isolation film is disposed between the LED chip and the photosensitive chip; The heat conduction component is disposed on the upper and lower surfaces of the isolation film and is in contact with both the upper and lower surfaces of the isolation film, and the heat conduction component uniformly transfers heat to the upper and lower surfaces of the isolation film.

[0007] In an optional implementation manner, the heat conduction component includes: a pair of heat spreaders; The heat spreaders are adapted to the isolation film, and one heat spreader is disposed between the LED chip and the isolation film, and the other heat spreader is disposed between the photosensitive chip and the isolation film; A through hole is opened at the center position of the heat spreader; Several strip-shaped members are disposed at the remaining positions of the heat spreader to form a mesh structure; One side of the strip-shaped member close to the isolation film is in a convex state, and the convex part of the strip-shaped member is embedded in the isolation film.

[0008] In an alternative embodiment, a plurality of heat conducting strips are provided on the side wall of the heat equalizing plate, and the heat conducting strips extend out of the isolation film.

[0009] In an alternative embodiment, one side of the heat equalizing plate below the isolation film close to the isolation film is in a concave state, that is, one side of the heat equalizing plate close to the isolation film is recessed towards the center position of the heat equalizing plate; One side of the heat equalizing plate above the isolation film close to the isolation film is in a convex state, that is, one side of the heat equalizing plate close to the isolation film protrudes towards the center position of the heat equalizing plate.

[0010] In an alternative embodiment, the photosensitive chip is disposed on the base island, the base island is connected to the lead frame through conductive silver paste, and the photosensitive chip is connected to the base island through conductive silver paste.

[0011] In an alternative embodiment, the LED chip and the photosensitive chip are respectively electrically connected to the lead frame, an input unit is formed between the LED chip and the lead frame, and an output unit is formed between the photosensitive chip and the lead frame.

[0012] In an alternative embodiment, a plastic package is disposed on the lead frame, and the plastic package covers the LED chip and the photosensitive chip.

[0013] In an alternative embodiment, the stacked optocoupler package structure further includes a lead frame, a base island is disposed on the lead frame, and the LED chip and the photosensitive chip are disposed above the base island from high to low; The LED chip and the photosensitive chip are respectively electrically connected to the lead frame.

[0014] In a second aspect, an embodiment of the present disclosure further provides a packaging method for the above-mentioned stacked optocoupler package structure, including: Coat conductive silver paste on the base island of the lead frame, and stick the photosensitive chip onto the conductive silver paste; Put the lead frame with the photosensitive chip stuck thereon into an anaerobic oven for constant temperature curing; Set the isolation mechanism on the photosensitive chip, and stick the LED chip onto the isolation mechanism; Put the lead frame with the LED chip stuck thereon into an anaerobic oven for constant temperature curing; Electrically connect the LED chip and the photosensitive chip to the pins of the lead frame respectively through bonding wires; Put the lead frame with the bonding wires stuck thereon into a mold, and inject plastic encapsulation material, and perform injection molding encapsulation through a press; The plastic encapsulant is formed by a separation and forming device to form a plastic encapsulation shell.

[0015] The beneficial effect of the present invention is that the stacked optocoupler package structure includes: an LED chip and a photosensitive chip; the LED chip is disposed above the photosensitive chip, and an isolation mechanism is disposed between the LED chip and the photosensitive chip; wherein the isolation mechanism includes: an isolation film and a heat conduction component; the isolation film is disposed between the LED chip and the photosensitive chip; the heat conduction component is disposed on the upper and lower surfaces of the isolation film and is in contact with both the upper and lower surfaces of the isolation film, and the heat conduction component uniformly transfers heat to the upper and lower surfaces of the isolation film, thereby realizing that when the isolation film is heated and cured, the heat can be uniformly transferred to the isolation film through the heat conduction component, so that the isolation film is uniformly heated and the stratification of the isolation film is avoided.

[0016] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by practicing the present invention. The objectives and other advantages of the present invention are achieved and obtained by the structure specifically pointed out in the specification and the drawings.

[0017] To make the above objectives, features, and advantages of the present invention more obvious and understandable, specific preferred embodiments are hereby given, and in conjunction with the accompanying drawings, the following detailed description is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 Schematic diagram of the internal structure of a stacked optocoupler package structure provided by an embodiment of the present disclosure; Figure 2 Schematic diagram of a stacked optocoupler package structure provided by an embodiment of the present disclosure; Figure 3 Schematic diagram of the structure of a heat conduction component provided by an embodiment of the present disclosure; Figure 4 Schematic diagram of the structure of a heat spreader provided by an embodiment of the present disclosure; Figure 5 Internal cross-sectional view of a stacked optocoupler package structure provided by an embodiment of the present disclosure; Figure 6 Schematic diagram of the leadless package structure of a stacked optocoupler package structure provided by an embodiment of the present disclosure.

[0020] In the figure: 1 LED chip; 2 photosensitive chip; 3 isolation mechanism, 31 isolation film, 32 heat conduction component, 321 heat dissipation plate, 322 through hole, 323 heat conduction bar, 324 bar-shaped part; 4 base island; 5 lead frame, 51 pin; 6 plastic package housing; 7 bonding wire. Specific implementation manners

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0022] As used herein, phrases such as "in one embodiment", "according to one embodiment", "in some embodiments", etc. generally refer to the fact that the specific features, structures, or characteristics after such phrases can be included in at least one embodiment of the present disclosure. Therefore, the specific features, structures, or characteristics can be included in more than one embodiment of the present disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, terms such as "example", "exemplary", etc. are used "for the purpose of serving as an example, instance, or illustration. Any embodiment, aspect, or design described herein as "example" or "exemplary" is not necessarily construed as being preferred or superior to other embodiments, aspects, or designs. Instead, the use of terms such as "example", "exemplary", etc. is intended to present concepts in a specific manner.

[0023] The general optocoupler packaging technology is to set the LED chip and the photosensitive chip opposite to each other, and use two lead frames to carry the corresponding chips respectively and then package them. After packaging, there is a certain distance between the LED chip and the photosensitive chip, resulting in slow product transmission characteristics, long response time of the photosensitive chip, and due to the long light propagation path, there is a certain light attenuation, which affects the product performance. The chips are arranged in a stacked structure, and an isolation film is set between the photosensitive chip and the LED chip. The photosensitive chip and the LED chip are connected by heating and curing, and a light transmission path is formed through the isolation film. However, delamination may occur during the heating and curing of the isolation film, resulting in deviation of red light propagation. The isolation film is usually composed of polymer materials (such as epoxy resin), and epoxy resin is not a good heat-conducting material. During the heating process, the uneven temperature distribution of the epoxy resin causes internal stress concentration, which in turn causes delamination. After the isolation film delaminates, refraction occurs when red light passes through, and the receiving end of the photosensitive chip cannot be correctly irradiated.

[0024] It should be noted that like reference numerals and letters refer to like items in the following figures; thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

[0025] Hereinafter, some embodiments of the present invention will be described in detail with reference to the drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0026] As Figure 1 and Figure 3 shown, at least one disclosed embodiment provides a stacked optocoupler packaging structure, including: an LED chip 1 and a photosensitive chip 2; the LED chip 1 is arranged above the photosensitive chip 2, and an isolation mechanism 3 is arranged between the LED chip 1 and the photosensitive chip 2; wherein the isolation mechanism 3 includes: an isolation film 31 and a heat-conducting component 32; the isolation film 31 is arranged between the LED chip 1 and the photosensitive chip 2; the heat-conducting component 32 is arranged on the upper and lower surfaces of the isolation film 31 and is in contact with both the upper and lower surfaces of the isolation film 31. The heat-conducting component 32 evenly transfers heat to the upper and lower surfaces of the isolation film 31, thereby realizing that when the isolation film 31 is heated and cured, the heat can be evenly transferred to the isolation film 31 through the heat-conducting component 32, so that the isolation film 31 is uniformly heated and delamination of the isolation film 31 is avoided.

[0027] In this embodiment, the isolation mechanism 3 can also achieve voltage electrical isolation between the LED chip 1 and the photosensitive chip 2.

[0028] In this embodiment, the LED chip 1 and the photosensitive chip 2 are arranged one above the other, greatly reducing the distance between the LED chip 1 and the photosensitive chip 2, accelerating the response time and transmission characteristics of the formed optoelectronic device product (stacked optocoupler), and having no light decay.

[0029] In this embodiment, an isolation mechanism 3 is arranged between the LED chip 1 and the photosensitive chip 2, and electrical isolation is formed through the isolation film 31 in the isolation mechanism 3. The isolation film 31 can form a light transmission path.

[0030] In this embodiment, in addition to the gallium arsenide infrared chip, the LED chip 1 also includes a red light LED and a blue light LED chip. The red / blue light LED chip can adapt to a working temperature of 150°C. The gallium arsenide infrared chip can only adapt to a working temperature of 125°C; the red / blue light LED chip can supplement the application of gallium arsenide at high temperatures, that is, it has better applications in new energy motors, BMS, charging piles, photovoltaic inverters, power plants, alternating tracks, and various outdoor work control fields compared with the gallium arsenide infrared chip.

[0031] As Figure 3 and Figure 4 shown, in an optional implementation manner, the heat conduction component 32 includes: a pair of heat spreaders 321; the heat spreaders 321 are adapted to the isolation film 31, and one of the heat spreaders 321 is arranged between the LED chip 1 and the isolation film 31, and the other heat spreader 321 is arranged between the photosensitive chip 2 and the isolation film 31; a through hole 322 is opened at the center position of the heat spreader 321; a plurality of strip-shaped members 324 are arranged at the remaining positions of the heat spreader 321 to form a mesh structure; the side of the strip-shaped member 324 close to the isolation film 31 is in a convex state, and the convex part of the strip-shaped member 324 is embedded in the isolation film 31.

[0032] In this embodiment, the through hole 322 opened at the center position of the heat spreader 321 is for facilitating the through hole 322 and the isolation film 31 to form a light transmission path, so that the light emitted by the LED chip 1 can irradiate on the photosensitive chip 2.

[0033] In this embodiment, the mesh-structured heat spreader 321 can make the heat transfer faster and more uniform, so that the isolation film 31 is heated more uniformly during the heating and curing process of the isolation film 31, thereby reducing stress concentration during the heating process and avoiding delamination of the isolation film 31.

[0034] In this embodiment, the convex part of the strip-shaped member 324 can be embedded in the isolation film 31, so that heat can be transferred to the isolation film 31 better, faster and more uniformly.

[0035] In this embodiment, the two uniform heat plates 321 transfer heat from the upper and lower surfaces of the isolation film 31 simultaneously, so that the isolation film 31 is heated more evenly, thereby reducing stress concentration during the heating process and avoiding delamination of the isolation film 31.

[0036] like Figure 5 As shown, in an optional embodiment, a plurality of heat-conducting strips 323 are equidistantly arranged on the side wall of the heat-distributing plate 321 in the circumferential direction, and the heat-conducting strips 323 extend out of the isolation film 31 .

[0037] In this embodiment, the heat transfer to the uniform heat plate 321 can be accelerated by the thermal conductive strips 323. Arranging multiple thermal conductive strips 323 can accelerate the heat transfer to the uniform heat plate 321 from multiple positions, so that the uniform heat plate 321 can transfer heat more evenly.

[0038] like Figure 5 As shown, in an optional embodiment, the side of the heat uniforming plate 321 below the isolation film 31 close to the isolation film 31 is in a concave state, that is, the side of the heat uniforming plate 321 close to the isolation film 31 is recessed toward the center of the heat uniforming plate 321; the side of the heat uniforming plate 321 above the isolation film 31 close to the isolation film 31 is in a convex state, that is, the side of the heat uniforming plate 321 close to the isolation film 31 is convex toward the center of the heat uniforming plate 321.

[0039] In this embodiment, the side of the uniform heat plate 321 below the isolation film 31 close to the isolation film 31 is concave away from the isolation film 31; the side of the uniform heat plate 321 above the isolation film 31 close to the isolation film 31 is convex away from the isolation film 31.

[0040] In this embodiment, the side of the heat-distributing plate 321 above the isolation film 31 close to the isolation film 31 is set to a convex state, and the side of the heat-distributing plate 321 below the isolation film 31 close to the isolation film 31 is set to a concave state, so that the light emitted by the LED chip 1 can be gathered toward the light-transmitting path through the reflection of the heat-distributing plate 321, so that the light can pass through the light-transmitting path and illuminate the photosensitive chip 2.

[0041] In this embodiment, the surface of the uniform heat plate 321 that contacts the photosensitive chip 2 and the LED chip 1 is a plane, so that the uniform heat plate 321 is firmly connected to the photosensitive chip 2 and the LED chip 1.

[0042] like Figure 3 As shown, in an optional embodiment, the photosensitive chip 2 is disposed on the base island 4, the base island 4 is connected to the lead frame 5 via a conductive silver paste, and the photosensitive chip 2 is connected to the base island 4 via a conductive silver paste.

[0043] In an alternative embodiment, the LED chip 1 and the photosensitive chip 2 are electrically connected to the lead frame 5 respectively. An input unit is formed between the LED chip 1 and the lead frame 5, and an output unit is formed between the photosensitive chip 2 and the lead frame 5.

[0044] In this embodiment, pins 51 corresponding to the input unit and pins 51 corresponding to the output unit are provided on the lead frame 5. The LED chip 1 and the photosensitive chip 2 are electrically connected to the corresponding pins 51 through bonding wires 7 respectively.

[0045] As Figure 2 shown, in an alternative embodiment, a plastic package 6 is provided on the lead frame 5. The plastic package 6 covers the LED chip 1 and the photosensitive chip 2. The pins 51 corresponding to the input unit extend out of the plastic package 6, and the pins 51 corresponding to the output unit extend out of the plastic package 6. Referring to Figure 6 , a pinless packaging method can also be adopted, that is, QFN (Quad Flat No-lead), quad flat no-lead package, or DFN (Dual Flat No-lead), dual flat no-lead package.

[0046] In this embodiment, the plastic package 6 can protect the LED chip 1 and the photosensitive chip 2.

[0047] In this embodiment, the overall process of the stacked optocoupler packaging structure is relatively simple, reducing the quality control cost. The whole material can pass the AOI vision inspection at one time. The distance between the LED chip 1 and the photosensitive chip 2 is close, the product response time is fast, the transmission characteristics are fast, the performance is better, and there is no light decay.

[0048] At least one other publicly disclosed embodiment also provides a stacked optocoupler packaging structure, including: a lead frame 5, a base island 4 is provided on the lead frame 5, and an LED chip 1 and a photosensitive chip 2 are provided above the base island 4 from high to low respectively; the LED chip 1 and the photosensitive chip 2 are electrically connected to the lead frame 5 respectively, thereby greatly reducing the distance between the LED chip 1 and the photosensitive chip 2, accelerating the response time of the formed optoelectronic device product (stacked optocoupler), accelerating the transmission characteristics, and having no light decay.

[0049] In an alternative embodiment, an isolation mechanism 3 is provided between the LED chip 1 and the photosensitive chip 2; wherein the isolation mechanism 3 includes: an isolation film 31 and a heat conduction component 32; the isolation film 31 is provided between the LED chip 1 and the photosensitive chip 2; the heat conduction component 32 is provided on the upper and lower surfaces of the isolation film 31 and is in contact with both the upper and lower surfaces of the isolation film 31, and the heat conduction component 32 uniformly transfers heat to the upper and lower surfaces of the isolation film 31.

[0050] At least one other publicly disclosed embodiment also provides a packaging method for the above-mentioned stacked optocoupler packaging structure, including: Step S1: Coat conductive silver paste on the base island 4 of the lead frame 5, and stick the photosensitive chip 2 onto the conductive silver paste; Step S2: Place the lead frame 5 with the photosensitive chip 2 adhered thereto into an anaerobic oven at 150°C - 175°C for constant temperature curing for 2 hours; Step S3: Paste a heat dissipation plate 321 onto the photosensitive chip 2, then paste another heat dissipation plate 321 onto the LED chip 1, and coat an isolation film 31 between the two heat dissipation plates 321; Step S4: Place the lead frame 5 with the LED chip 1 adhered thereto into an anaerobic oven at 60 - 120°C for constant temperature curing for 1 hour to improve the bonding between the LED chip 1 and the photosensitive chip 2; Step S5: Electrically connect the LED chip 1 and the photosensitive chip 2 to the pins 51 of the lead frame 5 respectively through bonding wires 7; Step S6: Place the lead frame 5 with the bonding wires 7 adhered thereto into a mold, and inject molding compound. Through press injection encapsulation, the chips are isolated from the outside; Step S7: Use a separation and forming device to form the molding compound into a plastic package shell 6; Step S8: Test the product with an AC high voltage of 3750V - 12000V, and sort and distinguish the high-voltage qualified products and unqualified products; Step S9: Print words, perform 3D inspection, tape or tube-pack the qualified products, and package them into the warehouse.

[0051] In summary, the present stacked optocoupler packaging structure includes: an LED chip 1 and a photosensitive chip 2; the LED chip 1 is arranged above the photosensitive chip 2, and an isolation mechanism 3 is arranged between the LED chip 1 and the photosensitive chip 2; wherein the isolation mechanism 3 includes: an isolation film 31 and a heat conduction component 32; the isolation film 31 is arranged between the LED chip 1 and the photosensitive chip 2; the heat conduction component 32 is arranged on the upper and lower surfaces of the isolation film 31 and is in contact with both the upper and lower surfaces of the isolation film 31. The heat conduction component 32 uniformly transfers heat to the upper and lower surfaces of the isolation film 31, thereby achieving that when the isolation film 31 is heated and cured, heat can be uniformly transferred to the isolation film 31 through the heat conduction component 32, making the isolation film 31 receive heat evenly and avoiding delamination of the isolation film 31.

[0052] In the description of the embodiments of the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", and "coupled" shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0053] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention. In addition, terms such as "first", "second" and other numerical terms used herein do not imply an order or sequence unless explicitly indicated herein. Thus, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer or section discussed above may be referred to as the second element, component, region, layer or section.

[0054] Spatially relative terms, such as "inner", "outer", "beneath", "below", "lower", "above", "upper", etc., may be used herein to facilitate describing one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. In addition to the orientation depicted in the figures, spatially relative terms are intended to encompass different orientations of the device in use or operation. For example, if the device in the figures is turned over, an element described as "beneath" or "below" another element or feature would then be oriented "above" the other element or feature. Thus, the exemplary term "beneath" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein are to be interpreted accordingly.

[0055] Based on the above inspiration from the ideal embodiments of the present invention, through the above description, relevant workers can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A stacked optocoupler package structure, characterized in that, Including: an LED chip (1) and a photosensitive chip (2); the LED chip (1) includes a red light LED chip, a blue light LED chip, and an infrared LED chip; the LED chip (1) is disposed above the photosensitive chip (2), and an isolation mechanism (3) is disposed between the LED chip (1) and the photosensitive chip (2); wherein the isolation mechanism (3) includes: an isolation film (31) and a heat conduction component (32); the isolation film (31) is disposed between the LED chip (1) and the photosensitive chip (2); the heat conduction component (32) is disposed on the upper and lower surfaces of the isolation film (31) and is in contact with both the upper and lower surfaces of the isolation film (31), and the heat conduction component (32) uniformly transfers heat to the upper and lower surfaces of the isolation film (31).

2. The stacked optocoupler package structure according to claim 1, wherein: the heat conduction component (32) includes: a pair of heat spreaders (321); the heat spreaders (321) are adapted to the isolation film (31), and one heat spreader (321) is disposed between the LED chip (1) and the isolation film (31), and the other heat spreader (321) is disposed between the photosensitive chip (2) and the isolation film (31); a through hole (322) is formed at the center position of the heat spreader (321); a plurality of strip-shaped members (324) are disposed at the remaining positions of the heat spreader (321) to form a mesh structure; the side of the strip-shaped member (324) close to the isolation film (31) is in a convex state, and the convex portion of the strip-shaped member (324) is embedded in the isolation film (31).

3. The stacked optocoupler package structure according to claim 2, wherein: a plurality of heat conduction strips (323) are disposed on the side wall of the heat spreader (321), and the heat conduction strips (323) extend out of the isolation film (31).

4. The stacked optocoupler package structure according to claim 2, wherein: the surface of the heat spreader (321) below the isolation film (31) close to the isolation film (31) is in a concave state, that is, the surface of the heat spreader (321) close to the isolation film (31) is recessed toward the center position of the heat spreader (321); the surface of the heat spreader (321) above the isolation film (31) close to the isolation film (31) is in a convex state, that is, the surface of the heat spreader (321) close to the isolation film (31) protrudes toward the center position of the heat spreader (321).

5. The stacked optocoupler package structure according to claim 1, wherein: the photosensitive chip (2) is disposed on a base island (4), the base island (4) is connected to a lead frame (5) through a conductive silver paste, and the photosensitive chip (2) is connected to the base island (4) through a conductive silver paste.

6. The stacked optocoupler package structure according to claim 1, wherein: the LED chip (1) and the photosensitive chip (2) are respectively electrically connected to the lead frame (5), an input unit is formed between the LED chip (1) and the lead frame (5), and an output unit is formed between the photosensitive chip (2) and the lead frame (5).

7. The stacked optocoupler package structure according to claim 6, wherein: A plastic package (6) is provided on the lead frame (5), and the plastic package (6) covers the LED chip (1) and the photosensitive chip (2).

8. The stacked optocoupler package structure according to claim 1, wherein: The stacked optocoupler package structure further includes a lead frame (5), a base island (4) is provided on the lead frame (5), and the LED chip (1) and the photosensitive chip (2) are arranged above the base island (4) from high to low; The LED chip (1) and the photosensitive chip (2) are electrically connected to the lead frame (5) respectively.

9. A packaging method adopted for the stacked optocoupler packaging structure according to any one of claims 1 to 8, characterized in that, Including: Coat conductive silver paste on the base island (4) of the lead frame (5), and stick the photosensitive chip (2) onto the conductive silver paste; Put the lead frame (5) with the photosensitive chip (2) stuck thereon into an anaerobic oven for constant temperature curing; Set the isolation mechanism (3) on the photosensitive chip (2), and stick the LED chip (1) onto the isolation mechanism (3); Put the lead frame (5) with the LED chip (1) stuck thereon into an anaerobic oven for constant temperature curing; Electrically connect the LED chip (1) and the photosensitive chip (2) to the pins (51) of the lead frame (5) respectively through bonding wires (7); Put the lead frame (5) with the bonding wires (7) stuck thereon into a mold, and inject plastic encapsulation material, and perform injection encapsulation through a press; Form the plastic encapsulation material through a separation and forming device to form the plastic package (6).

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