Miniature high-reliability packaging structure and preparation method thereof

Abstract

The invention discloses a miniature high-reliability packaging structure and a preparation method thereof. The packaging structure comprises a substrate, a cover plate and a packaged element located between the substrate and the cover plate, the packaged element is electrically and fixedly connected with the substrate, and the area, except the packaged element, between the substrate and the cover plate is filled with curable pouring sealant, so that the packaged element is surrounded by the pouring sealant. According to the preparation method, the temporary box dam or the elastic film layer is formed on the cover plate, so that the encapsulated element is surrounded by the pouring sealant and then the pouring sealant is cured. The packaging structure is simple and small in size, the process is simplified, the material cost is saved, the heat dissipation efficiency can be enhanced, the junction temperature is reduced, the tolerance of the junction temperature is controlled within a preset range, and the product yield of the packaging structure produced in batches is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of packaging technology, in particular to a micro high-reliability packaging structure and a preparation method thereof, especially to a micro high-reliability packaging structure based on side edge packaging of pouring glue, using a temporary dam or elastic film layer process, and a preparation method thereof. BACKGROUND

[0002] High-reliability packaging technology is a key branch of integrated circuit packaging field, which focuses on ensuring that the device can work long-term and stably under harsh environmental conditions. This technology is crucial for fields such as aerospace, military equipment, exploration, and others that have extremely high safety requirements.

[0003] Figure 1 is a schematic diagram of a high-reliability chip packaging structure suitable for mass production according to Chinese Patent No. CN114823552B. As Figure 1 shown, the packaging structure of this patent includes a substrate a1, a chip a4, a ring frame a2, and a cover plate a3. The chip a4 is fixed on the substrate, the ring frame a2 is sealingly connected to the substrate a1 and surrounds the chip a4, and the cover plate a3 covers the ring frame and the chip and is sealingly connected with the ring frame. However, the ring frame a2 of this packaging structure occupies a large area, resulting in a large size of the packaging structure, which cannot meet the requirements of modern high-reliability chips pursuing high density and low cost.

[0004] Moreover, in the above-mentioned prior art, when mass production is carried out, due to the thickness error of the ring frame a2, the cover plate a3 is stacked and fixed on the ring frame a2, so the distance between the bottom surface of the cover plate a3 and the top surface of the chip a4 cannot be effectively controlled in the process, which makes the distance between the top of the chip a4 and the cover plate a3 of each packaging structure in the same product line have a large tolerance, thereby causing the junction shell thermal resistance of the chip top heat dissipation to have a large tolerance, resulting in a decrease in the yield of mass-produced packaging structures.

[0005] In addition, due to the fact that the tolerance of the distance between the bottom surface of the cover plate a3 and the top surface of the chip a4 cannot be effectively controlled, the same thickness of heat dissipation material that makes good contact with both the cover plate a3 and the chip a4 cannot be inserted between the cover plate a3 and the chip a4, which makes it impossible to effectively reduce the tolerance of the junction shell thermal resistance of the chip top heat dissipation even if additional heat dissipation material is applied in the process. SUMMARY

[0006] (I) Technical problems to be solved This invention aims to address two issues: firstly, the large footprint, low efficiency in mass production, and high cost of existing high-reliability chip packaging structures; and secondly, the difficulty in controlling the tolerance of the junction thermal resistance of existing high-reliability chip packaging structures, which leads to low yield in mass production.

[0007] (II) Technical Solution To address the aforementioned technical problems, this invention proposes a miniature, high-reliability packaging structure, comprising a substrate, a cover plate, and an encapsulated element located between the substrate and the cover plate. The encapsulated element is electrically fixedly connected to the substrate. The area between the substrate and the cover plate, excluding the encapsulated element, is filled with a curable potting compound, such that the potting compound surrounds the encapsulated element. The viscosity coefficient of the potting compound at 25°C before curing is less than 1000 mPa·s, and the difference between its CTE value and that of the encapsulated element in the horizontal direction after curing is less than or equal to 40 ppm / °C and greater than or equal to 20 ppm / °C.

[0008] According to a preferred embodiment of the present invention, the distance between the outer side of the encapsulated element and the outer side of the potting compound is between 0.2 mm and 0.5 mm.

[0009] According to a preferred embodiment of the present invention, the difference in CTE value between the substrate and the packaged element in the horizontal direction is less than or equal to 15 ppm / ℃; the difference in CTE value between the cover plate and the packaged element in the horizontal direction is less than or equal to 15 ppm / ℃.

[0010] According to a preferred embodiment of the present invention, the top surface of the encapsulated element is connected to the bottom surface of the cover plate by a welding material.

[0011] According to a preferred embodiment of the present invention, when the potting compound is not cured, the distance between the bottom surface of the cover plate and the top surface of the substrate can be adjusted to remain within a predetermined range, so that the tolerance of the thermal resistance of the top heat dissipation shell of the encapsulated element after the potting compound is cured remains within a predetermined range.

[0012] According to a preferred embodiment of the present invention, a heat dissipation layer is provided on the top surface of the encapsulated element, and the distance between the bottom surface of the cover plate and the top surface of the substrate is adjusted so that the heat dissipation layer is in close contact with the bottom surface of the cover plate and the encapsulated element.

[0013] According to a preferred embodiment of the present invention, the heat dissipation layer is a directional heat dissipation material of a predetermined thickness.

[0014] A second aspect of this invention provides a method for fabricating a miniature, highly reliable packaging structure, comprising the following steps: S1-1. The encapsulated component is electrically fixed on the top surface of the substrate; S1-2. The top surface of the encapsulated component is welded or bonded to the cover plate. S1-3. A temporary dam is formed on the cover plate in the peripheral area of ​​the assembly of the substrate and the encapsulated element. S1-4. Inject uncured potting compound into the temporary enclosure and fill the space between the substrate and the cover plate. Then cure the potting compound. The viscosity coefficient of the potting compound at 25°C before curing is less than 1000 mPa·s. After curing, the difference between the potting compound and the CTE value of the encapsulated element in the horizontal direction is less than or equal to 40 ppm / °C and greater than or equal to 20 ppm / °C. S1-5. Cut the cover plate along the side of each substrate to obtain multiple encapsulation structures.

[0015] According to a preferred embodiment of the present invention, in steps S1-3, the height of the temporary dam is less than or equal to the distance between the bottom surface of the encapsulated element and the cover plate.

[0016] According to a preferred embodiment of the present invention, in steps S1-3, when the distance between the bottom surface of the encapsulated element and the cover plate is d and the height of the temporary dam 8 is h, the condition 0.1mm≥dh≥0 is satisfied.

[0017] A third aspect of this invention provides a method for fabricating a miniature, highly reliable packaging structure, comprising the following steps: S2-1. The encapsulated component is electrically fixed on the top surface of the substrate. S2-2. An elastic film layer with a pre-made opening is attached to the substrate, such that the encapsulated component is located within the pre-made opening; S2-3. Attach the cover plate to the elastic film layer. The cover plate is welded to the encapsulated component or a heat dissipation layer is provided. The cover plate has through holes, and each opening of the elastic film layer is aligned with at least two through holes of the two cover plates. S2-4. Inject uncured potting compound into the temporary dam through the through hole on the cover plate. The viscosity coefficient of the potting compound at 25°C before curing is less than 1000 mPa·s, and the difference between the potting compound and the CTE value of the encapsulated component in the horizontal direction after curing is less than or equal to 40 ppm / °C and greater than or equal to 20 ppm / °C. S2-5. Curing the potting compound; S2-6. Cut the substrate and cover plate along the inside of the through holes on the cover plate to obtain multiple encapsulation structures.

[0018] According to a preferred embodiment of the present invention, in steps S2-3, the distance between the substrate and the cover plate is controlled at a standard distance D. SThis ensures that the distance between the top surface of the encapsulated component and the bottom surface of the cover plate is exactly equal to the thickness of the heat dissipation layer.

[0019] According to a preferred embodiment of the present invention, the thickness D of the elastic membrane layer when uncompressed O The standard distance D S The difference is between 0.1 and 0.5 mm.

[0020] A fourth aspect of the present invention provides a method for fabricating a miniature high-reliability packaging structure, comprising the following steps: S3-1. The encapsulated component is electrically fixed on the top surface of the substrate. S3-2. Multiple temporary dams are formed on the cover plate, and the area enclosed by the temporary dams can accommodate the encapsulated component; S3-3. Inside the temporary dam, heat dissipation material is fixed on the cover plate to form a heat dissipation layer; S3-4. Inject uncured potting compound into the temporary dam. The viscosity coefficient of the potting compound at 25°C before curing is less than 1000 mPa·s, and the difference between the potting compound and the CTE value of the encapsulated component in the horizontal direction after curing is less than or equal to 40ppm / °C and greater than or equal to 20ppm / °C. S3-5. The substrate plate on which the encapsulated components are fixed is attached to the cover plate plate, such that each encapsulated component is surrounded by uncured potting compound in each of the temporary dams, and the potting compound fills all the space between the substrate and the cover plate. S3-6. Curing the potting compound; S3-7. Cut the substrate and cover plate along the inner side of the temporary dam to obtain multiple encapsulation structures.

[0021] According to a preferred embodiment of the present invention, in steps S3-5, the distance between the substrate and the cover plate is controlled at a standard distance D. S This ensures that the distance between the top surface of the encapsulated component and the bottom surface of the cover plate is exactly equal to the thickness of the heat dissipation layer.

[0022] According to a preferred embodiment of the present invention, the height of the temporary dam is less than or equal to the distance between the bottom surface of the encapsulated element and the cover plate.

[0023] According to a preferred embodiment of the present invention, when the distance between the bottom surface of the encapsulated element and the cover plate is d and the height of the temporary dam 8 is h, the condition 0.1mm≥dh≥0 is satisfied.

[0024] The fifth aspect of the present invention also proposes a chip packaging structure, which is prepared by the method for preparing a miniature high-reliability packaging structure according to any of the above claims.

[0025] (III) Beneficial Effects The miniature high-reliability packaging structure and corresponding preparation method of the present invention use special potting compound to encapsulate the sides, and use temporary dams or elastic film layers in the process to replace the traditional ring frame or cap structure. This not only makes the packaging structure simpler and smaller, but also makes the process of forming the dam easier than forming the ring frame or cap structure, and saves material costs.

[0026] The area of ​​the interface between the layers of materials in the packaging structure of the present invention is also reduced, and the reduction of the interface area reduces the stress accumulation effect, thereby increasing the structure's resistance to mechanical and thermal shock.

[0027] This invention uses directional heat dissipation materials instead of welding connections, which not only enhances heat dissipation efficiency and reduces junction temperature, but also allows the junction temperature tolerance to be controlled within a predetermined range, thereby improving the product yield of the package structure in mass production. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of an existing high-reliability chip packaging structure suitable for mass production.

[0029] Figure 2 This is a schematic diagram of the micro high-reliability chip packaging structure according to the first embodiment of the present invention.

[0030] Figures 3 to 8 This is a schematic diagram of the micro high-reliability chip packaging process according to the first embodiment of the present invention.

[0031] Figure 9 This is a schematic diagram of a micro-high reliability chip package structure with controllable junction temperature tolerance according to the second embodiment of the present invention.

[0032] Figure 10 and Figure 11 A photograph of the actual product of the second embodiment is shown, in which Figure 10 Its external shape was displayed. Figure 11 Its internal structure is shown.

[0033] Figures 12 to 16 This is a schematic diagram of the packaging process of a micro-high reliability chip with controllable junction temperature tolerance according to the second embodiment of the present invention.

[0034] Figure 17 This is a schematic diagram of a miniature, highly reliable package structure with controllable junction temperature tolerance according to the third embodiment of the present invention.

[0035] Figures 18 to 24 This is a schematic diagram of the micro-high reliability chip packaging process with controllable junction temperature tolerance according to the third embodiment of the present invention. Detailed Implementation

[0036] To address the aforementioned technical problems, this invention proposes a high-reliability packaging structure with a smaller size. For mass production of packaging structures, a smaller size means that more packaging structures can be arranged on the same area of ​​substrate, thereby producing more packaged devices simultaneously, which improves production efficiency. Simultaneously, a smaller size also means less packaging material is used, thus saving costs. More importantly, a smaller size also means that the interface area between the layers of material in the packaging structure is reduced. A smaller interface area reduces the stress accumulation effect, thereby increasing the structure's resistance to mechanical and thermal shock.

[0037] Therefore, the inventors of this invention further optimized the structure, materials, and processes based on existing high-reliability packaging structures, ultimately making miniature high-reliability packaging structures possible. Furthermore, the fabrication process of this invention, specifically designed for miniature high-reliability packaging structures, unexpectedly resulted in more controllable junction temperature tolerances. The controllability of junction temperature tolerances is another crucial indicator in the field of high-reliability packaging technology, significantly impacting the yield of mass-produced products.

[0038] As is well known, junction temperature usually refers to the operating temperature of a die. In this invention, junction temperature refers to the operating temperature of the packaged component within the package structure. We know that junction temperature significantly affects the lifespan of the packaged component. Therefore, for high-reliability package structures, controlling the junction temperature tolerance of mass-produced package structures within a small range can greatly improve the yield of mass-produced products. The factor directly affecting junction temperature is the junction-to-case thermal resistance, i.e., the thermal resistance of the heat conduction path between the packaged component and the package shell. Therefore, by controlling the tolerance of the junction-to-case thermal resistance, the tolerance of the junction temperature can be well controlled, thereby controlling the lifespan of mass-produced packaged components and improving product yield.

[0039] Therefore, the high-reliability packaging structure obtained by the manufacturing process proposed in this invention has a simpler and more durable structure. It eliminates the ring frame of the existing packaging structure and fills the entire side with potting compound. Specifically, the packaging structure of this invention includes a substrate, a cover plate, and an encapsulated element located between the substrate and the cover plate. The encapsulated element is electrically fixedly connected to the substrate. The area between the substrate and the cover plate, excluding the encapsulated element, is filled with curable potting compound, such that the potting compound surrounds the encapsulated element.

[0040] In this invention, potting compound specifically refers to a curable resin that is poured around the encapsulated component in a high-reliability encapsulation structure and provides a highly reliable sealing effect.

[0041] According to the inventor's simulation and actual experimental measurement, the potting compound of the present invention should meet two conditions: (1) low viscosity coefficient: the viscosity coefficient at room temperature (25°C) before curing is less than 1000 mPa·s (cps), preferably less than 600 mPa·s; (2) CTE matching the encapsulated element: the difference between the CTE value of the encapsulated element and the CTE value of the encapsulated element in the horizontal direction after curing is less than or equal to 40 ppm / °C, but greater than or equal to 20 ppm / °C.

[0042] First, the viscosity coefficient determines the capillary filling ability of the resin material. Materials with low viscosity coefficients are more likely to fill into capillary pores, thereby eliminating voids within the material itself. The miniature high-reliability encapsulation structure of this invention uses a potting compound with a viscosity coefficient of less than 1000 mPa·s, which will not produce a "popcorn effect" due to the presence of small pores at temperatures exceeding 100°C, thus preventing cracks from forming within the potting compound. Since the potting compound of this invention not only aims to eliminate voids between devices (such as the space between BGAs) but also considers the small voids generated within the material itself, it requires a lower viscosity coefficient to produce better flowability. As mentioned above, the viscosity coefficient of the potting compound of this invention before curing is below 1000 mPa·s, more preferably below 600 mPa·s.

[0043] Secondly, the matching of the CTE of the cured potting compound with the encapsulated component ensures the integrity of the encapsulation structure. To meet the requirements of high-reliability encapsulation (able to maintain the integrity of the encapsulation structure after more than 500 temperature cycles at -65℃ to 150℃), this invention requires, on the one hand, that the cured potting compound should be sufficiently soft and elastic, i.e., its absolute CTE value should be high to absorb deformation energy and prevent stress concentration from being transferred to the chip. Through simulation and actual testing by the inventors of this invention, the difference between the CTE of the cured potting compound and the encapsulated component should be greater than or equal to 20 ppm / ℃. Secondly, the difference in CTE between the cured potting compound and the encapsulated component should match in the horizontal direction to prevent excessive stress difference at the interface from causing cracks or warping. Through simulation and actual testing by the inventors of this invention, a difference in CTE between the cured potting compound and the encapsulated component of less than 40 ppm / ℃ is suitable.

[0044] The packaging process and structure of this invention break away from conventional packaging design concepts. It eliminates the need to surround the sides of the packaged component with packaging materials such as substrates, metal, or ceramic rings, resulting in smaller size and less material usage. The material savings reduce board and process costs, making it cost-effective to replace ordinary filler with potting compound. Furthermore, the potting compound solution still achieves the high-reliability packaging requirements. Even more unexpectedly, this structural simplification leads to improvements in the packaging process, which further reduces manufacturing costs. Simultaneously, it brings unexpected technical benefits to the packaging structure, namely, controllable junction temperature tolerance.

[0045] This is because, by removing the ring frame or other encapsulation materials or components placed between the cover plate and the substrate, the distance control between the cover plate and the substrate is not affected during the encapsulation process, resulting in more precise dimensional control between mass-produced encapsulation structures. Specifically, when no potting compound is injected, or when potting compound is injected but not yet cured, the distance between the bottom surface of the cover plate and the top surface of the substrate can be adjusted to remain within a predetermined range. This distance directly determines the heat dissipation path of the encapsulated component, thus keeping the thermal resistance tolerance of the top heat dissipation shell of the encapsulated component after the potting compound has cured within a predetermined range. Consequently, the junction temperature tolerance can be controlled within a predetermined range, improving the product yield of mass-produced encapsulation structures.

[0046] In a more preferred embodiment of the present invention, to improve the reliability of the high-reliability packaging structure, particularly to enable the packaging structure to withstand more than 500 temperature cycles from -65°C to 150°C, the difference in CTE values ​​between the substrate and the encapsulated component in the horizontal direction is less than or equal to 15 ppm / °C, and the difference in CTE values ​​between the cover plate and the encapsulated component in the horizontal direction is also less than or equal to 15 ppm / °C. Furthermore, the potting compound of the present invention also has a high glass transition temperature to ensure that the high-reliability packaging structure maintains stable performance even at high operating temperatures.

[0047] This invention is not limited to the connection method between the packaged element and the cover plate or substrate. However, as a preferred embodiment, the top surface of the packaged element and the bottom surface of the cover plate are connected by a welding material. Using a welding connection helps to increase the mechanical strength of the package structure.

[0048] If the packaging structure requires higher heat dissipation, the present invention also proposes another preferred embodiment, namely, providing a heat dissipation layer on the top surface of the packaged component. As mentioned earlier, the distance between the cover plate and the substrate of the present invention can be precisely adjusted, that is, the distance between the bottom surface of the cover plate and the top surface of the substrate can be precisely adjusted so that the heat dissipation layer can be in close contact with both. Furthermore, since the heat dissipation layer material used in mass production usually comes from the same source, the thickness of the heat dissipation layer used in mass-produced structures is usually fixed. This allows the distance between the cover plate and the packaged component to be adjusted to just accommodate the heat dissipation layer, so that the distance between the heat dissipation layer and the bottom surface of the cover plate, or the distance between the heat dissipation layer and the top surface of the packaged component, can be controlled to extremely small values. In each mass-produced packaging structure, the tolerance of this distance is extremely small, which prevents the heat dissipation layer from being over-compressed and thus reducing its performance or becoming thinner, and also prevents poor contact with the components on both sides and hindering heat dissipation. As a specific embodiment, the present invention preferably makes the distance between the heat dissipation layer and the cover plate less than 5 μm.

[0049] In a preferred embodiment of the present invention, the material of the heat dissipation layer can be a thermally conductive paste (thermal grease) with high thermal conductivity, or it can be a phase change material or liquid metal, or it can be graphene or nanogel (thermal conductive gel). More preferably, the heat dissipation layer is a directional heat dissipation material with a predetermined thickness. The directional heat dissipation material of the present invention refers to a material with high thermal conductivity in a specific direction, thereby having high thermal conductivity along the heat dissipation path from the encapsulated component to the cover plate side.

[0050] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0051] Figure 2 This is a schematic diagram of the miniature high-reliability package structure according to the first embodiment of the present invention. See also... Figure 2 The packaging structure of this embodiment of the invention includes a substrate 1 and a cover plate 3, and a packaged element 4 located between the substrate 1 and the cover plate 3. The packaged element 4 is a chip, but it can also be other electronic components. The packaged element 4 is fixed and electrically connected to the substrate 1 by flip-chip bonding. In this embodiment, the electrical connection uses a gold-gold interconnect method, i.e., it is connected through a gold ball array 7. It should be noted that the packaged element 4 of the present invention can be a single element, multiple elements arranged at intervals, or a combination of multiple elements.

[0052] The soldering area between the substrate 1 and the encapsulated component 4 is filled using an underfill adhesive 6. While filling the area between the substrate 1 and the encapsulated component with underfill adhesive 6 is a conventional technique, this embodiment differs in that the sides of the encapsulated component 4, as well as the sides of the gold ball array and the underfill adhesive 6, are filled with potting compound 10, so that the encapsulated component 4 is surrounded by potting compound. The outer surface of the potting compound 10 remains flush with the sides of the substrate 1 and the cover plate 3, and there are no other structures on the outer surface of the potting compound 10.

[0053] Furthermore, in this embodiment, the top surface of the encapsulated component 4 and the bottom surface of the cover plate 3 are connected by a solder layer 5 to obtain better mechanical properties, and the solder also has good heat dissipation capabilities. However, the present invention is not limited to this; in some other embodiments, the solder layer 5 may be omitted, or other materials with a fixing connection function may be used instead.

[0054] In this embodiment, the potting compound selected is an epoxy resin with a CTE difference between the encapsulated element and the cured component that is less than or equal to 40 ppm / ℃ and greater than or equal to 20 ppm / ℃. Simultaneously, both the substrate 1 and the cover plate 3 in this embodiment are made of BT resin substrate, with a CTE difference between the substrate and the encapsulated component 4 within 15 ppm / ℃. Figures 3 to 8 This is a schematic diagram of the first packaging process flow for a miniature high-reliability chip according to the first embodiment of the present invention. This process flow corresponds to... Figure 2 The packaging structure of the embodiment shown specifically includes the following steps: S1-1. The encapsulated component is electrically fixed on the top surface of the substrate.

[0055] Figure 3 This diagram illustrates the process of bonding the packaged component to the substrate. For example... Figure 3 As shown, in this embodiment, a chip serving as the encapsulated element 4 is fixed on a substrate 1. The upper and lower surfaces of the substrate 1 are covered with metal conductive layers and interconnected through reserved lines in the substrate. The encapsulated element 4 can be fixed to the substrate 1 by flip-chip bonding. After flip-chip bonding, an underfill process is performed on the bonding area between the substrate 1 and the encapsulated element 4, in this case, underfill adhesive 6 is used.

[0056] It should be noted that during mass production, substrate 1 is cut from a large substrate material. That is, during mass production, multiple encapsulated components 4 are fixed at equal intervals on the substrate material, and then cut, thus enabling mass production. Figure 3 The structure shown.

[0057] Furthermore, in this embodiment, the electrical connection between the packaged component 4 and the substrate 1 is achieved through gold-to-gold interconnection, and the die leads are soldered to the pads on the substrate using a solderless, low-temperature ultrasonic soldering method. This gold-to-gold interconnection method overcomes the Kirkendall effect that occurs during conventional soldering between aluminum pads and gold balls, preventing solder joint cracking and further improving structural stability and thermal shock resistance in the integrated circuit packaging environment.

[0058] S1-2. The top surface of the component to be packaged is welded and fixed to the cover plate.

[0059] Figure 4 and Figure 5 The diagram shows a component being fixed to a cover plate with its top surface facing down. (Example) Figure 4 As shown, the top surface of the encapsulated component 4 is facing down, that is, with the substrate 1 on top and the encapsulated component 4 on the bottom, and it is moved toward the cover plate 3 located below and soldered and fixed by applying solder.

[0060] like Figure 4 and Figure 5 As shown, the area of ​​cover plate 3 is slightly larger than that of substrate 1, but this is only a schematic diagram. For clarity, only one encapsulation structure is shown in this diagram. However, in practice, cover plate 3 can be made of a larger cover plate material for mass production of the encapsulation structure. During mass production, a large number of encapsulated components 4 can be simultaneously soldered at equal intervals on the large cover plate material, and the cover plate can be cut in subsequent steps. The cover plate material can be a copper through-hole substrate (FR4, BT, ABF, etc.), or a material with copper inlay (including oxygen-free copper, molybdenum copper, or tungsten copper) technology to improve thermal conductivity and reduce costs.

[0061] S1-3. On the cover plate, a temporary dam is formed in the outer area of ​​the assembly of each substrate and the packaged component.

[0062] Figure 6 A schematic diagram of the process for forming a temporary dam 8 on the cover plate 3 is shown. As mentioned earlier, the cover plate 3 is actually a large-area cover plate material in which a large number of substrates 1 and encapsulated components 4 have been fixed together by welding. In order to subsequently wrap the sides of the encapsulated components 4 with potting compound, which is in a liquid or flowing state when filled, a temporary dam 8 needs to be formed around the location of the potting compound to confine the potting compound to a small area around the encapsulated components 4.

[0063] like Figure 6As shown, the temporary dam 8 is formed in the outer region of the orthographic projection of the substrate 1 onto the cover plate 3, or slightly offset outward from the outer edge of the projection. The height of the temporary dam 8 should not be too low, so that the potting compound cannot completely cover the side of the encapsulated element 4; the height of the temporary dam 8 should also not be too high, so as not to completely block the nozzle of the glue gun used to inject the potting compound. A preferred height of the temporary dam 8 is approximately equivalent to the distance between the bottom surface of the encapsulated element 4 and the cover plate 3, i.e., the height of the side of the chip facing the substrate 1, or slightly less than this height. More preferably, if the distance between the bottom surface of the encapsulated element 4 and the cover plate 3 is d, and the height h of the temporary dam 8 is 0.1 mm ≥ dh ≥ 0.

[0064] The present invention does not impose any particular limitation on the material of the temporary dam 8, since the temporary dam 8 only serves a temporary limiting function and does not exist in the final encapsulation structure. Existing materials that are easy to apply to the surface of the sheet and are easy to cut are all acceptable options. For example, common thermosetting resin materials, such as silicone resin, are easy to apply and cure, easy to cut, and readily available, and are therefore preferred materials.

[0065] S1-4. Inject uncured potting compound into the temporary enclosure and fill the space between the substrate and the cover plate, then cure the potting compound.

[0066] Figure 7 A schematic diagram shows the process of filling the dam with sealant. (Example) Figure 7 As shown, potting compound 10 is injected into the dam. During filling, potting compound 10 is in an uncured state and has good fluidity. At the same time, since the process is usually carried out in a high vacuum state, potting compound 10 will quickly fill the space between substrate 1 and cover plate 3 and overflow from the top of temporary dam 8. This makes the four sides of the encapsulated element 4 tightly wrapped by potting compound 10, which plays a sealing and protection role for the encapsulated element. For example, potting compound 10 can be epoxy resin with a cured CTE value of 35 ppm / ℃. However, the present invention is not limited to this. Potting compound that meets the conditions mentioned above can be used, namely (1) low viscosity coefficient: the viscosity coefficient at room temperature (25℃) before curing is less than 1000 mPa·s, preferably less than 600 mPa·s; (2) CTE matching the encapsulated element: the difference between the cured CTE value and the encapsulated element in the horizontal direction is less than or equal to 40 ppm / ℃ and greater than or equal to 20 ppm / ℃.

[0067] After the uncured potting compound 10 is filled, the next step is to cure the potting compound 10. In this embodiment, heat curing is used, but in other embodiments, room temperature curing can also be used.

[0068] S1-5. Cut the cover plate material along the side of each substrate to obtain multiple packaging structures.

[0069] Figure 8 A schematic diagram shows the process of cutting the cover plate material. (For example...) Figure 8 As shown, in this step, since substrate 1 has already been cut to a predetermined size, the final packaging structure can be obtained simply by cutting the cover plate material along the side of the substrate. Figure 8 As can be seen, since the temporary dike 8 is located outside the projection of the cover plate, it is completely cut off. This results in the final high-reliability encapsulation structure.

[0070] As can be seen from the process steps of the above embodiments, the miniature high-reliability packaging structure and corresponding preparation method of this embodiment of the present invention use a temporary dam 8 instead of the traditional ring frame or cap structure, which not only makes the packaging structure simpler and smaller in size, but also makes the process steps of forming the dam easier than forming the ring frame or cap structure, and saves material costs.

[0071] Furthermore, in the smaller-sized packaging structure obtained by the above-described packaging structure and corresponding preparation method of the present invention, the area of ​​the interface between each layer of material is also reduced. The reduction of the interface area reduces the stress accumulation effect, thereby increasing the structure's resistance to mechanical and thermal shock.

[0072] Figure 9 This is a schematic diagram of a micro-high reliability chip package structure with controllable junction temperature tolerance according to the second embodiment of the present invention.

[0073] Compared to Figure 2 The first embodiment shown, Figure 9 The main difference in the packaging structure of the embodiment is that the packaged component 4 and the bottom surface of the cover plate 3 can not only be soldered together, but a heat dissipation layer 9 made of heat dissipation material can also be provided between them to further enhance the heat dissipation performance of the packaging structure of the present invention, while making the junction temperature tolerance controllable.

[0074] In this embodiment, the heat dissipation layer 9 is preferably made of a directional heat dissipation material, which has the function of directional heat dissipation, allowing the heat of the encapsulated component 4 to be dissipated directionally from one side of the cover plate. Compared with solder, it loses some performance in mechanical strength, but has better heat dissipation performance; for example, it can be hexagonal boron nitride or graphene. In other embodiments, the heat dissipation layer can also be made of thermally conductive paste (thermal grease), phase change material, liquid metal, nano-adhesive (thermal gel), etc.

[0075] The directional heat dissipation material of the present invention preferably has a high compression ratio, for example, between 25% and 50%, so that even if the material thickness is inconsistent, it can be corrected during the process.

[0076] Figure 10 and Figure 11 A photograph of the actual product of the second embodiment is shown, in which Figure 10 Its external shape was displayed. Figure 11 Its internal structure is shown. For example... Figure 10 As shown, in this embodiment, only the substrate 1, the cover plate 3, and the potting compound 10 located between the substrate 1 and the cover plate 3 are visible from the outside. Figure 11 As can be seen, inside the packaging structure of this embodiment, the chip, which is the packaged element 4, is surrounded by potting compound 10, and a heat dissipation layer 9 made of graphene is provided between the chip and the cover plate.

[0077] The following description further illustrates this embodiment through a detailed explanation of the packaging process. It should be noted that, although... Figure 9 , 10 11 shows that a heat dissipation layer 9 made of heat dissipation material is provided between the encapsulated component 4 and the bottom surface of the cover plate 3. However, for the specific encapsulation process below, the connection method of soldering between the encapsulated component 4 and the bottom surface of the cover plate 3 can still be realized.

[0078] Figures 12 to 16 This is a schematic diagram of the packaging process flow for a micro-sized, high-reliability chip with controllable junction temperature tolerance according to the second embodiment of the present invention. This process flow corresponds to... Figure 9 The packaging structure of the embodiment shown.

[0079] S2-1. The encapsulated component is electrically fixed on the top surface of the substrate.

[0080] like Figure 12 As shown, this step is similar to step S1-1 in the previous embodiment, but the difference is that the subsequent steps of this step do not immediately cut the substrate material. That is, compared with step S1-1, there is no step of cutting the substrate, which can further simplify the process in mass production.

[0081] S2-2. An elastic film layer with a pre-made opening is attached to a substrate, such that the encapsulated component is located within the pre-made opening.

[0082] like Figure 13 As shown, the second embodiment uses an elastic film layer 2 with pre-fabricated openings, replacing the temporary dam 8 of the first embodiment. The elastic film layer 2 can be attached to the substrate by adhesive. In fact, the size of the opening of the elastic film layer 2 is equivalent to or slightly larger than the size of the space enclosed by the temporary dam 8 in the first embodiment, but its height should be higher than that of the temporary dam 8. The opening of the elastic film layer 2 essentially serves the same function as the temporary dam 8, namely, as a space for receiving uncured potting compound.

[0083] It should be noted that the elastic membrane layer 2 in this embodiment is made of rubber material, but other elastic materials may also be used. The elastic membrane layer 2 has a certain degree of elasticity, thereby allowing it to be compressed in the thickness direction.

[0084] S2-3. Attach the cover plate to the elastic film layer. Weld or provide a heat dissipation layer between the cover plate and the encapsulated component. The cover plate has through holes, and each opening of the elastic film layer is aligned with at least two through holes of the two cover plates.

[0085] Figure 14 The diagram illustrates the process of attaching the cover plate to the elastic film layer. The elastic film layer 2 can also be attached to the cover plate using adhesive. Although only one encapsulation structure is shown in the diagram, in mass production, the substrate, elastic film layer, and cover plate all cover large areas. Compared to the process of forming temporary dams, the large area of ​​the elastic film layer allows for easy pre-fabrication of multiple openings, eliminating the need for complex dispensing and curing steps, thus significantly reducing the number of processes.

[0086] Furthermore, considering that the elastic membrane layer 2 is elastic, the elastic membrane layer 2 can be compressed when the cover plate 3 is placed on the elastic membrane layer and pressure is applied. Thus, the distance D between the substrate and the cover plate can be precisely controlled in this step.

[0087] In this step, the distance D between the substrate and the cover plate can be measured in real time through the through holes on the cover plate 3, which allows for precise control of the top surface of the encapsulated component 4. Figure 20 , Figure 21 The distance between the lower surface of the chip and the bottom surface of the cover plate 3.

[0088] Therefore, when the cover plate 3 covers the elastic film layer 2 and pressure is applied, solder can be applied between the encapsulated component 4 and the cover plate 3 for welding, and the thickness of the solder can be controlled. Alternatively, a heat dissipation layer 9 can be provided between the cover plate and the encapsulated component. When the cover plate 3 covers the elastic film layer 2 and pressure is applied, the distance D between the substrate and the cover plate is controlled so that the heat dissipation layer 9 is in close contact with both the encapsulated component 4 and the cover plate 3. The heat dissipation layer 9 will not be excessively squeezed, thus reducing its performance or becoming thinner, nor will it have poor contact with the components on both sides, thus hindering heat dissipation.

[0089] More specifically, such as Figure 14 As shown, by appropriately compressing the elastic membrane layer 2, the distance between the substrate and the cover plate is controlled at a standard distance D. SThis design ensures that the distance between the top surface of the encapsulated component 4 and the bottom surface of the cover plate 3 is exactly equal to the thickness of the heat dissipation layer 9, allowing the heat dissipation layer 9 to be in close contact with both the encapsulated component and the cover plate 3. This allows for precise control of the material (solder or heat dissipation layer) and the thermal conduction distance along the heat dissipation path of the encapsulated component. Consequently, the thermal resistance tolerance of the top heat dissipation shell of the encapsulated component after the potting compound has cured remains within a predetermined range, thereby controlling the junction temperature tolerance within a predetermined range and improving the product yield of the encapsulation structure in mass production.

[0090] The achievement of the aforementioned technical effects essentially depends on three conditions: First, the elastic membrane layer 2 can be compressed in the thickness direction, so it does not prevent the cover plate from moving relative to the substrate material.

[0091] Secondly, the thickness of the components between the substrate and the cover plate is fixed. Firstly, the thickness channel of the packaged component 4 has high precision, especially the chip thickness tolerance, which is extremely small and negligible. The thickness of the electrical connection structure (e.g., BGA ball array) between the chip and the substrate is also controlled with extremely high precision. As for the heat dissipation layer, its thickness can be made consistent by controlling its amount or specifications. For example, the thickness of the graphene-based directional heat dissipation layer 9 used in the embodiments of this invention is usually cut from the same batch of sheets, so its thickness can also be considered fixed. Therefore, the packaged component 4, the electrical connection structure, and the heat dissipation layer will not have a substantial impact on the distance between the top surface of the packaged component 4 and the bottom surface of the cover plate 3.

[0092] Third, the through holes on the cover plate 3 can be used as channels for laser ranging. Through laser ranging, the distance between the substrate and the cover plate can be controlled in real time and accurately, which makes it easier to control the distance in the process.

[0093] Due to the above three reasons, the above embodiments of the present invention can indeed achieve good control over the material and heat conduction distance on the heat dissipation path of the packaged component, which is also the unexpected technical effect achieved by the packaging structure and corresponding preparation method of the present invention.

[0094] Since the elastic membrane layer 2 can be compressed, its thickness D when uncompressed is... O Slightly higher than the standard distance D S Preferred, D O -D S The value is between 0.1mm and 0.5mm.

[0095] S2-4. Inject uncured potting compound into the temporary dam through the through holes in the cover plate.

[0096] Figure 15A schematic diagram of the potting compound injection step is shown. After the cover plate 3 is formed on the elastic membrane layer 2, uncured potting compound 10 can be injected into the opening of the elastic membrane layer 2 through at least one through hole on the cover plate. At least one other through hole serves as a vent or a discharge hole. The potting compound 10 used in this embodiment is the same as that in the first embodiment. Since the viscosity coefficient of the potting compound of the present invention is less than 1000 mPa·s at 25°C before curing, and preferably less than 600 mPa·s, it can penetrate and fill all the spaces within the opening of the elastic membrane layer 2. Finally, a small amount of potting compound should overflow from the vent or discharge hole.

[0097] S2-5, Curing potting compound.

[0098] This step is similar to the curing process of the potting compound in steps S1-4 of the first embodiment, and it is also preferably carried out by heat curing.

[0099] S2-6. Cut the substrate and cover plate along the inside of the through holes on the cover plate to obtain multiple encapsulation structures.

[0100] Figure 16 A schematic diagram showing the process of cutting the substrate and cover plate is displayed. (For example...) Figure 16 As shown, in this step, unlike the previous embodiment, the substrate and cover plate are cut simultaneously, along the inside of the through hole on the cover plate. This removes the elastic film layer, thus obtaining the final encapsulation structure.

[0101] As can be seen from the process steps of the above embodiments, the miniature high-reliability packaging structure and corresponding preparation method of the present invention not only use a temporary elastic film layer to replace the traditional ring frame or cap structure, but also use heat dissipation material to replace welding connection, and thereby improve the packaging process. This not only enhances heat dissipation efficiency and reduces junction temperature, but also makes the packaging structure simpler, smaller in size, simplifies the process, and saves material costs.

[0102] Furthermore, in addition to increasing the structure's resistance to mechanical and thermal shock, the packaging structure of this embodiment also allows the junction temperature tolerance to be controlled within a predetermined range, thereby improving the product yield of the packaging structure in mass production.

[0103] Figure 17 This is a schematic diagram of a miniature, high-reliability package structure with controllable junction temperature tolerance according to the third embodiment of the present invention. The package structure of this third embodiment is basically the same as that of the second embodiment, except that in this third embodiment, the method of soldering between the packaged element 4 and the bottom surface of the cover plate 3 is excluded, and only the method of setting a heat dissipation layer 9 between the two is included.

[0104] Figures 18 to 24This is a schematic diagram of the micro-high reliability chip packaging process with controllable junction temperature tolerance according to the third embodiment of the present invention. This process flow corresponds to... Figure 15 The packaging structure of the embodiment shown.

[0105] S3-1. The encapsulated component is electrically fixed on the top surface of the substrate.

[0106] like Figure 18 As shown, this step is similar to step S2-1 in the second embodiment, and will not be described again here.

[0107] S3-2. Multiple temporary dams are formed on the cover plate, and the area enclosed by the temporary dams can accommodate the encapsulated component.

[0108] Figure 19 The diagram shown illustrates the process of forming a temporary dam 8 on the cover plate 3. It should be noted that step S3-2 is not necessarily performed after step S3-1, and therefore this step is relatively independent of steps S3-1 and S3-2.

[0109] like Figure 19 As shown, this step also involves batch forming multiple temporary dams 8 on the cover plate material, the size of which is similar to... Figure 2 The process is similar to that of the first embodiment, but it should be slightly larger than the size of the encapsulated element 4 so that the potting compound in the temporary dam 8 will completely encapsulate the encapsulated element 4 in subsequent steps.

[0110] The method of forming the dam 8 and the materials used for the dam are similar to those in the first embodiment, and will not be described again here. The height of the temporary dam 8 should not be too high to avoid obstructing the proximity between the substrate and the cover plate.

[0111] S3-3. Inside the temporary dam, heat dissipation material is fixed to the cover plate to form a heat dissipation layer.

[0112] Figure 20 A schematic diagram shows the process of fixing the heat dissipation layer 9, made of heat dissipation material, to the cover plate inside the dam. (See diagram for example.) Figure 20 As shown, the heat dissipation material is located essentially at the center of the dam, and its positioning and size correspond to the positioning and size of the encapsulated element 4. To maximize heat dissipation efficiency, its area is preferably the same as or slightly larger than the area of ​​the top surface of the encapsulated element 4.

[0113] S3-4. Inject uncured potting compound into the temporary dam.

[0114] Figure 21A schematic diagram of the potting compound injection step is shown. After a temporary dam 8 is formed on the cover plate and the heat dissipation material is fixed, the side with the temporary dam 8 and heat dissipation material facing upwards can be injected into the temporary dam 8 with uncured potting compound 10. It is important to note that the amount of potting compound 10 injected into the temporary dam 8 should be such that when the encapsulated component 4 is placed into the dam, the potting compound 10 can fill all the space between the substrate 1 and the cover plate 3. Alternatively, when the temporary dam 8 has a suitable thickness, a small amount of potting compound should overflow from the temporary dam 8 when the encapsulated component 4 is placed into the dam.

[0115] S3-5. The substrate plate with the encapsulated components fixed on it is attached to the cover plate plate, so that each encapsulated component is surrounded by uncured potting compound in each temporary enclosure, and the potting compound fills all the space between the substrate and the cover plate.

[0116] Figure 22 and 23 This diagram illustrates the process of bonding the substrate material to the cover plate material. Figure 20 As shown, the side of the cover plate 3 with the temporary barrier 8 fixed to it faces upwards, and the side of the substrate 1 with the encapsulated component 4 fixed to it faces downwards. The substrate is then moved downwards to adhere to the cover plate. Although only one encapsulation structure is shown in the figure, in reality, both the substrate and the cover plate are large-area materials in mass production.

[0117] In this step, by measuring the distance D between the substrate and the cover plate in real time, the top surface of the encapsulated component 4 can be precisely controlled. Figure 22 , Figure 23 The lower surface of the chip in the middle) and the bottom surface of the cover plate 3 ( Figure 22 , Figure 23 The distance between the heat dissipation layer 9 and the upper surface of the cover plate 3 is such that the heat dissipation layer 9 is in close contact with both the packaged component and the cover plate 3. The heat dissipation layer 9 will not be excessively squeezed, thus reducing its performance or becoming thinner, nor will it have poor contact with the components on both sides, thus hindering heat dissipation.

[0118] More specifically, such as Figure 23 As shown, by controlling the distance between the substrate and the cover plate to a standard distance D... S This design ensures that the distance between the top surface of the encapsulated component 4 and the bottom surface of the cover plate 3 is exactly equal to the thickness of the heat dissipation layer 9, allowing the heat dissipation layer 9 to be in close contact with both the encapsulated component and the cover plate 3. This allows for precise control of the material (heat dissipation layer) and thermal conduction distance along the heat dissipation path of the encapsulated component, thus maintaining the thermal resistance tolerance of the top heat dissipation shell of the encapsulated component within a predetermined range after the potting compound has cured. Consequently, the junction temperature tolerance can be controlled within a predetermined range, improving the product yield of the encapsulation structure in mass production.

[0119] In summary, achieving the aforementioned technical effects essentially depends on four conditions: First, the aforementioned distance control is performed before the potting compound has cured. Since the potting compound has not yet cured, it will not hinder the adjustment of the distance between the substrate and the cover plate.

[0120] Secondly, the height of the temporary dam should not obstruct the proximity between the substrate and the cover plate. As mentioned earlier, the height of the temporary dam 8 should not be too low to prevent the potting compound from completely covering the side of the encapsulated component. Simultaneously, the height of the temporary dam 8 in this embodiment should not be too high to avoid obstructing the proximity between the substrate and the cover plate. Similar to the first embodiment, a preferred height of the temporary dam 8 is approximately equivalent to the distance between the bottom surface of the encapsulated component 4 and the cover plate 3, i.e., the height of the side of the chip facing the substrate 1, or slightly less than this height. More preferably, if the distance between the bottom surface of the encapsulated component 4 and the cover plate 3 is d, and the height h of the temporary dam 8 is 0.1mm ≥ dh ≥ 0.

[0121] Third, the thickness of the components between the substrate and the cover plate is fixed. First, the thickness channel of the packaged component 4 has high precision, especially the thickness tolerance of the chip, which is extremely small and negligible. The thickness of the electrical connection structure (e.g., BGA ball array) between the chip and the substrate is also controlled with extremely high precision. In addition, the thickness of the heat dissipation layer 9 used in this invention can be strictly controlled, for example, it is cut from the same batch of sheets, so its thickness can also be considered fixed. Therefore, the packaged component 4, the electrical connection structure, and the directional heat dissipation layer will not have a substantial impact on the distance between the top surface of the packaged component 4 and the bottom surface of the cover plate 3.

[0122] Fourth, by setting through holes (not shown in the figure) around the temporary dam on the cover plate, since there are no other components in the area around the temporary dam, the through holes can be used as a channel for laser ranging. Through laser ranging, the distance between the substrate and the cover plate can be controlled in real time and accurately, which makes it easier to control the distance in the process.

[0123] Due to the above four reasons, the above embodiments of the present invention can indeed achieve good control over the material and heat conduction distance on the heat dissipation path of the packaged component, which is also the unexpected technical effect achieved by the packaging structure and corresponding preparation method of the present invention.

[0124] S3-6, Curing potting compound.

[0125] This step is similar to the curing process of the potting compound in steps S1-4 of the first embodiment, and it is also preferably carried out by heat curing.

[0126] S3-7. Cut the substrate and cover plate along the inner side of the temporary dam to obtain multiple encapsulation structures.

[0127] Figure 24 A schematic diagram showing the process of cutting the substrate and cover plate is displayed. (For example...) Figure 22 As shown, in this step, unlike the previous embodiment, the substrate and cover plate are cut simultaneously along the inner side of the temporary dam, thus removing the temporary dam and obtaining the final encapsulation structure.

[0128] As can be seen from the process steps of the above embodiments, the miniature high-reliability packaging structure and corresponding preparation method of the present invention not only use a temporary dam 8 to replace the traditional ring frame or cap structure, but also use heat dissipation material to replace welding connection, and thereby improve the packaging process. This not only enhances heat dissipation efficiency and reduces junction temperature, but also makes the packaging structure simpler, smaller in size, simplifies the process, and saves material costs.

[0129] Furthermore, in addition to increasing the structure's resistance to mechanical and thermal shock, the packaging structure of this embodiment also allows the junction temperature tolerance to be controlled within a predetermined range, thereby improving the product yield of the packaging structure in mass production.

[0130] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A miniature high-reliability packaging structure, comprising a substrate, a cover plate, and a packaged element located between the substrate and the cover plate, wherein the packaged element is electrically fixedly connected to the substrate, characterized in that: Between the substrate and the cover plate, the area excluding the encapsulated element is filled with curable potting compound, such that the potting compound surrounds the encapsulated element. The potting compound has a viscosity coefficient of less than 1000 mPa·s at 25°C before curing, and the difference between its CTE value and that of the encapsulated component in the horizontal direction after curing is less than or equal to 40 ppm / °C and greater than or equal to 20 ppm / °C.

2. The miniature high-reliability packaging structure according to claim 1, characterized in that: The distance between the outer side of the encapsulated element and the outer side of the potting compound is between 0.2 mm and 0.5 mm.

3. The miniature high-reliability packaging structure according to claim 1 or 2, characterized in that: The difference in CTE value between the substrate and the packaged component in the horizontal direction is less than or equal to 15 ppm / ℃. The difference in CTE value between the cover plate and the encapsulated component in the horizontal direction is less than or equal to 15 ppm / ℃.

4. The miniature high-reliability packaging structure according to claim 3, characterized in that: The top surface of the encapsulated component is connected to the bottom surface of the cover plate by welding material.

5. The miniature high-reliability packaging structure according to claim 1, characterized in that: When the potting compound is not cured, the distance between the bottom surface of the cover plate and the top surface of the substrate can be adjusted to remain within a predetermined range, so that the thermal resistance tolerance of the top heat dissipation shell of the encapsulated component after the potting compound is cured remains within a predetermined range.

6. The miniature high-reliability packaging structure according to claim 5, characterized in that: The top surface of the encapsulated component is provided with a heat dissipation layer, and the distance between the bottom surface of the cover plate and the top surface of the substrate is adjusted so that the heat dissipation layer is in close contact with the bottom surface of the cover plate and the encapsulated component.

7. The miniature high-reliability packaging structure according to claim 6, characterized in that: The heat dissipation layer is a directional heat dissipation material of a predetermined thickness.

8. A method for fabricating a miniature, high-reliability packaging structure, characterized in that, Includes the following steps: S1-1. The encapsulated component is electrically fixed on the top surface of the substrate; S1-2. The top surface of the encapsulated component is welded or bonded to the cover plate. S1-3. A temporary dam is formed on the cover plate in the peripheral area of ​​the assembly of the substrate and the encapsulated element. S1-4. Inject uncured potting compound into the temporary enclosure and fill the space between the substrate and the cover plate. Then cure the potting compound. The viscosity coefficient of the potting compound at 25°C before curing is less than 1000 mPa·s. After curing, the difference between the potting compound and the CTE value of the encapsulated element in the horizontal direction is less than or equal to 40 ppm / °C and greater than or equal to 20 ppm / °C. S1-5. Cut the cover plate along the side of each substrate to obtain multiple encapsulation structures.

9. The method for fabricating a miniature high-reliability packaging structure according to claim 8, characterized in that, In steps S1-3, the height of the temporary dam is less than or equal to the distance between the bottom surface of the encapsulated element and the cover plate.

10. The method for fabricating a miniature high-reliability packaging structure according to claim 9, characterized in that, In steps S1-3, when the distance between the bottom surface of the encapsulated element and the cover plate is d and the height of the temporary dam 8 is h, the condition 0.1mm≥dh≥0 is satisfied.

11. A method for fabricating a miniature, high-reliability packaging structure, characterized in that, Includes the following steps: S2-1. The encapsulated component is electrically fixed on the top surface of the substrate. S2-2, An elastic film layer with a pre-made opening is attached to the substrate, such that the encapsulated element is located inside the opening; S2-3. Attach the cover plate to the elastic film layer. The cover plate is welded to the encapsulated component or a heat dissipation layer is provided. The cover plate has through holes, and each opening of the elastic film layer is aligned with at least two through holes of the two cover plates. S2-4. Inject uncured potting compound into the temporary dam through the through hole on the cover plate. The viscosity coefficient of the potting compound at 25°C before curing is less than 1000 mPa·s, and the difference between the potting compound and the CTE value of the encapsulated component in the horizontal direction after curing is less than or equal to 40 ppm / °C and greater than or equal to 20 ppm / °C. S2-5. Curing the potting compound; S2-6. Cut the substrate and cover plate along the inside of the through holes on the cover plate to obtain multiple encapsulation structures.

12. The method for fabricating a micro high-reliability packaging structure according to claim 11, characterized in that, In steps S2-3, the distance between the substrate and the cover plate is controlled at a standard distance D. S This ensures that the distance between the top surface of the encapsulated component and the bottom surface of the cover plate is exactly equal to the thickness of the heat dissipation layer.

13. The method for fabricating a miniature high-reliability packaging structure according to claim 12, characterized in that, The thickness D of the elastic membrane layer when it is not compressed O The standard distance D S The difference is between 0.1 and 0.5 mm.

14. A method for fabricating a miniature, highly reliable packaging structure, characterized in that, Includes the following steps: S3-1. The encapsulated component is electrically fixed on the top surface of the substrate. S3-2. Multiple temporary dams are formed on the cover plate, and the area enclosed by the temporary dams can accommodate the encapsulated component; S3-3. Inside the temporary dam, heat dissipation material is fixed on the cover plate to form a heat dissipation layer; S3-4. Inject uncured potting compound into the temporary dam. The viscosity coefficient of the potting compound at 25°C before curing is less than 1000 mPa·s, and the difference between the potting compound and the CTE value of the encapsulated component in the horizontal direction after curing is less than or equal to 40ppm / °C and greater than or equal to 20ppm / °C. S3-5. The substrate plate on which the encapsulated components are fixed is attached to the cover plate plate, such that each encapsulated component is surrounded by uncured potting compound in each of the temporary dams, and the potting compound fills all the space between the substrate and the cover plate. S3-6. Curing the potting compound; S3-7. Cut the substrate and cover plate along the inner side of the temporary dam to obtain multiple encapsulation structures.

15. The method for fabricating a micro high-reliability packaging structure according to claim 14, characterized in that, In steps S3-5, the distance between the substrate and the cover plate is controlled at a standard distance D. S This ensures that the distance between the top surface of the encapsulated component and the bottom surface of the cover plate is exactly equal to the thickness of the heat dissipation layer.

16. The method for fabricating a miniature high-reliability packaging structure according to claim 15, characterized in that, The height of the temporary dam is less than or equal to the distance between the bottom surface of the encapsulated element and the cover plate.

17. The method for fabricating a miniature high-reliability packaging structure according to claim 16, characterized in that, When the distance between the bottom surface of the encapsulated element and the cover plate is d and the height of the temporary dam 8 is h, the condition 0.1mm≥dh≥0 is satisfied.

18. A chip packaging structure, characterized in that, It is prepared by the method of fabrication of the micro high-reliability packaging structure according to any one of claims 8 to 17.

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