Fan-out chip packaging structure and packaging process thereof

Abstract

The invention relates to the technical field of integrated circuit manufacturing, in particular to a fan-out chip packaging structure and a packaging process thereof. Comprising a first plastic package body, a chip is fixedly connected to one side of the first plastic package body, a second plastic package body is fixedly connected to the side, close to the chip, of the first plastic package body, a heat dissipation piece is fixedly connected into the second plastic package body, two symmetrically-distributed connecting strips are fixedly connected to the side, close to the chip, of the heat dissipation piece, and a detection plate attached to the chip is fixedly connected to the two connecting strips jointly. The detection plate is fixedly connected with a plurality of abutting strips. The contact state of the abutting strip and the heat dissipation piece is controlled through thermal expansion and cold contraction of the detection plate and the abutting strip, then the heat exchange efficiency of the chip and the outside world is controlled, when the chip is initially started, the heat exchange efficiency of the chip and the outside world is reduced, the chip rapidly reaches the normal working temperature, and after the chip works normally, the working temperature of the chip is reduced. And the heat exchange efficiency of the chip and the outside is increased, so that the chip can work normally without increasing the system power consumption and influencing the normal heat dissipation of the chip.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit manufacturing technology, and in particular to a fan-out chip packaging structure and its packaging process. Background Technology

[0002] Fan-out chip packaging is a key technology in advanced packaging. It involves directly embedding the bare chip inside the package and using wafer-level redistribution technology to "fan out" the I / O interfaces from the central area of ​​the chip and redistribute them to its peripheral areas. This design successfully overcomes the limitation of chip area on the number of pins, thereby achieving higher integration density, thinner package form factor, and more competitive cost-effectiveness. Therefore, it is widely used in many fields such as mobile communications and high-performance computing.

[0003] However, when electronic devices equipped with such chips are initially started up in extremely cold regions, they face severe low-temperature challenges due to the low chip temperature: the physical properties of semiconductor materials change significantly at low temperatures, leading to reduced carrier mobility, threshold voltage drift, and consequently, chip timing errors, decreased driving capability, or even complete functional failure. Currently, common countermeasures mainly include installing heating resistors or adding thermal insulation materials, but both methods have obvious drawbacks: heating resistors increase power consumption while also increasing system complexity and potential failure risks; while thermal insulation materials can slow down the intrusion of external low temperatures, they can hinder the dissipation of heat during chip operation, easily leading to chip overheating and affecting its stable operation and lifespan. Summary of the Invention

[0004] This invention provides a fan-out chip packaging structure and its packaging process to overcome the shortcomings of existing chips when applied in extremely cold regions, such as increased power consumption and affected heat dissipation.

[0005] The technical solution is as follows: A fan-out chip packaging structure includes: a first molding compound, a chip fixedly attached to one side of the first molding compound, a plurality of copper pillars electrically connected to the chip fixedly attached inside the first molding compound, a redistribution layer disposed on the other side of the first molding compound, all the copper pillars being electrically connected to the redistribution layer, UBM pads disposed on the redistribution layer, a plurality of solder joints disposed on the side of the UBM pads away from the chip, the solder joints being electrically connected to the redistribution layer through the UBM pads, a second molding compound fixedly attached to the side of the first molding compound near the chip, a heat sink fixedly attached inside the second molding compound, two symmetrically distributed connecting strips fixedly attached to the side of the heat sink near the chip, the two connecting strips jointly fixedly attached to a detection board that is attached to the chip, a plurality of equidistantly distributed abutment strips fixedly attached to the side of the detection board near the heat sink, the abutment strips being used to contact the heat sink after thermal expansion.

[0006] Furthermore, multiple fins are fixed to the side of the heat sink away from the chip, and the fins are used to increase the area of ​​the heat sink for heat exchange with the outside world.

[0007] Furthermore, from the middle of the detection plate towards the connecting strips on both sides, the thickness of all the abutment strips gradually decreases, which is used to control the sum of the contact areas between all the abutment strips and the heat sink according to the temperature of the detection plate.

[0008] Furthermore, the distance between two adjacent fins gradually decreases from the middle of the detection plate toward the connecting strips on both sides.

[0009] Furthermore, the connecting strip is made of an elastic material, which allows the distance between the detection plate and the heat sink to change.

[0010] Furthermore, the cross-section of the connecting strip is arc-shaped.

[0011] Furthermore, the first molding compound, the chip, the second molding compound, and the heat sink together form a receiving cavity, and the receiving cavity contains a filling material, the thermal conductivity of which is lower than that of the heat sink and the detection plate.

[0012] Furthermore, the filling material is a phase change material, used to provide support for the chip when the chip is not in operation.

[0013] Furthermore, an elastic cylinder is fixed to the inner side of the second encapsulation body, the elastic cylinder being used to provide space for the expansion of the filler material, the detection plate, and the abutment strip.

[0014] A packaging process for a fan-out chip, used to produce the aforementioned fan-out chip packaging structure, is characterized by comprising the following steps: Step 1: Fabricate copper pillars on the chip working surface of the wafer, and perform thinning and dicing on the wafer to meet the packaging size and performance requirements; Step 2: Obtain the chip's parameter information, and according to the chip's parameter information, carve a groove on the surface of the temporary carrier board that is large enough to accommodate the chip. Apply an adhesive layer in the groove to provide basic support for the subsequent fixation of the chip. Step 3: After rigorously testing the chip to ensure its performance meets the standards, place the chip with its working surface facing up precisely in the groove of the temporary carrier board, so that the working surface of the chip is coplanar with the temporary carrier board. Step 4: Using EMC material, a reconstruction wafer is fabricated through a molding process, and then cured to form the first molding compound; Step 5: Grind the first molding compound to precisely expose the copper pillars. Create a redistribution layer and UBM pads on the exposed copper pillars, and create solder joints on the UBM pads. Step Six: Fabricate heat sink components, connecting strips, detection plates, abutment strips, and fins, and utilize the phase change characteristics of the filler material to connect the heat sink components, connecting strips, detection plates, abutment strips, and fins with the filler material and elastic cylinder into one piece within the mold; Step 7: Remove the temporary carrier board and adhesive layer, and use the filler material to fit onto the chip to fix the positions of the chip, heat sink, connecting strip, detection board, abutment strip, fins, filler material and elastic cylinder; Step 8: Using EMC material, a reconstruction wafer is fabricated through a molding process, and then cured to form a second molding compound. The second molding compound is then thinned and cut.

[0015] The beneficial effects of adopting the above technical solution are as follows: the present invention relies on the thermal expansion and contraction of the detection plate and the contact strip to control the contact state between the contact strip and the heat sink, thereby controlling the heat exchange efficiency between the chip and the outside world. When the chip is initially started, the heat exchange efficiency between the chip and the outside world is reduced, so that the chip can quickly reach the normal operating temperature. After the chip is working normally, the heat exchange efficiency between the chip and the outside world is increased. In this way, the chip can work normally without increasing the system power consumption and without affecting the normal heat dissipation of the chip.

[0016] Based on the temperature control of the chip, the contact area between the contact strip and the heat sink is adjusted. As the heat generated by the chip gradually increases, the expansion of the detection board and the contact strip gradually increases, thereby increasing the contact area between the contact strip and the heat sink. This improves the heat exchange efficiency between the chip and the outside world, enhances the heat dissipation efficiency of the chip, and keeps the chip temperature stable.

[0017] By relying on the deformation of the connecting strip, the distance between the detection board and the heat sink can be changed, thereby making room for the expansion of the chip and the detection board and reducing the internal thermal stress of the chip when the temperature changes.

[0018] Encasing the chip with filler material provides support and protection against impacts when the chip is not in operation. It also absorbs and contains some heat when the chip is working and keeps the chip warm after it stops working, allowing it to quickly reach normal operating temperature after restarting. In addition, the filler material absorbs the heat emitted by the chip during its initial operation, allowing the chip to gradually heat up and reducing the risk of thermal shock. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a three-dimensional structural diagram of the first encapsulated body and the elastic cylinder of the present invention; Figure 3 This is a three-dimensional structural diagram of the chip and detection board of the present invention; Figure 4 This is an exploded view of the chip, redistribution layer, and detection board of the present invention; Figure 5 This is a three-dimensional structural diagram of the detection plate and the abutment strip of the present invention.

[0020] The markings in the attached diagram are: 1-first molding compound, 2-chip, 3-copper pillar, 4-rewiring layer, 5-UBM pad, 6-solder joint, 7-second molding compound, 8-heat sink, 9-connecting strip, 10-detection board, 11-abutment strip, 12-fin, 13-filler material, 14-elastic cylinder. Detailed Implementation

[0021] In the description of this invention, it should be understood that the terms "upper," "lower," "inner," and "outer," etc., used in this invention to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. Example 1

[0022] This embodiment discloses a fan-out chip packaging structure to solve the problems of increased power consumption and affected heat dissipation when existing chips are applied in extremely cold regions.

[0023] See Figures 1 to 5 A fan-out chip package structure includes: a first molding compound 1, a chip 2 fixedly attached to the lower side of the first molding compound 1, a plurality of copper pillars 3 electrically connected to the chip 2 fixedly attached inside the first molding compound 1, a redistribution layer 4 disposed on the upper side of the first molding compound 1, all copper pillars 3 being electrically connected to the redistribution layer 4, UBM pads 5 disposed on the redistribution layer 4, a plurality of solder points 6 disposed on the upper side of the UBM pads 5, and the solder points 6 being electrically connected to the redistribution layer 4 through the UBM pads 5. The connection and function of the chip 2, copper pillars 3, redistribution layer 4, UBM pads 5 and solder points 6 are all prior art and will not be described in detail here; a second molding compound is fixedly attached to the lower side of the first molding compound 1. The encapsulation body 7 has a heat sink 8 fixedly attached inside. Two connecting strips 9 are symmetrically distributed on the upper side of the heat sink 8. The two connecting strips 9 are jointly fixed to a detection plate 10 that is in contact with the chip 2. Multiple abutment strips 11 are equidistantly distributed in the left-right direction on the lower side of the detection plate 10. The number of abutment strips 11 can be determined according to the length of the detection plate 10 in the left-right direction. Here, the number of abutment strips 11 is nine. The abutment strips 11 are used to contact the heat sink 8 after they and the detection plate 10 expand due to heat. The heat sink 8, connecting strips 9, detection plate 10 and abutment strips 11 can be made of metal materials with elasticity and strong thermal conductivity, such as copper and silver.

[0024] The above configuration enables the contact state between the contact strip 11 and the heat sink 8 to be controlled by the thermal expansion and contraction of the detection board 10 and the contact strip 11. Thus, when the chip 2 is initially started, the contact strip 11 and the heat sink 8 are not in contact, which reduces the heat exchange efficiency between the chip 2 and the outside world through the detection board 10, the contact strip 11 and the heat sink 8. After the chip 2 is working normally, the contact strip 11 and the heat sink 8 are brought into contact, thereby increasing the heat exchange efficiency between the chip 2 and the outside world and ensuring normal heat dissipation during the operation of the chip 2. This ensures the normal use of the chip 2 without increasing the system power consumption or affecting the normal heat dissipation of the chip 2.

[0025] When chip 2 is initially started, the temperature of both chip 2 and the external environment is low. In this case, chip 2 is only connected to heat sink 8 through connecting strip 9 and detection board 10. At this time, the heat exchange efficiency between detection board 10 and heat sink 8 is low, which in turn makes the heat exchange efficiency between chip 2 and the external environment low. As the working time of chip 2 increases, chip 2 gradually reaches the normal working temperature. During this process, the heat of chip 2 is transferred to detection board 10 and contact strip 11, causing detection board 10 and contact strip 11 to expand. When the temperature of chip 2 continues to increase, contact strip 11 comes into contact with heat sink 8, thus increasing the heat exchange efficiency between detection board 10 and heat sink 8, and thus increasing the heat exchange efficiency between chip 2 and the external environment. As the temperature of chip 2 changes, the contact state between contact strip 11 and heat sink 8 also changes, thus maintaining the stable temperature of chip 2 during operation. Example 2

[0026] This embodiment is a further optimization based on Embodiment 1.

[0027] See Figure 2 and Figure 5 Multiple fins 12 distributed in the left-right direction are fixedly connected to the lower side of the heat sink 8. The fins 12 are used to increase the area of ​​heat exchange between the heat sink 8 and the outside world, thereby improving the heat exchange efficiency between the chip 2 and the outside world when it is working normally.

[0028] The heat sink 8 and fins 12 can be integrally formed using CNC technology, as can the connecting strip 9, detection plate 10 and abutment strip 11. Example 3

[0029] This embodiment is a further optimization based on embodiment 2, providing the function of adaptive heat exchange efficiency between chip 2 and the outside world.

[0030] See Figure 5 From the middle of the detection plate 10 towards the connecting strips 9 on both sides, the thickness of all the abutment strips 11 gradually decreases, which is used to control the sum of the contact areas between all the abutment strips 11 and the heat sink 8 according to the temperature of the detection plate 10.

[0031] The above settings enable the contact area between the contact strip 11 and the heat sink 8 to be controlled according to the temperature of the chip 2. As the heat generated by the chip 2 gradually increases, the expansion of the detection plate 10 and the contact strip 11 gradually increases, thereby increasing the contact area between all the contact strips 11 and the heat sink 8. This improves the heat exchange efficiency between the chip 2 and the outside world, enhances the heat dissipation efficiency of the chip 2, and keeps the temperature of the chip 2 stable.

[0032] See Figure 5 From the middle of the detection board 10 towards the connecting strips 9 on both sides, the distance between two adjacent fins 12 gradually decreases; this increases the range of variation in the heat exchange efficiency between the chip 2 and the outside world, and improves the adaptability to various situations during the operation of the chip 2. Example 4

[0033] This embodiment is a further optimization based on embodiment 3, in order to provide the function of reducing the thermal stress of chip 2.

[0034] See Figures 3 to 5 The connecting strip 9 is made of elastic material so that the distance between the detection plate 10 and the heat sink 8 can be changed; the cross section of the connecting strip 9 is arc-shaped so that the connecting strip 9 can be bent under the pressure of the detection plate 10.

[0035] The above setup enables the distance between the detection plate 10 and the heat sink 8 to change by the deformation of the connecting strip 9, thereby providing space for the expansion of the chip 2 and the detection plate 10 and reducing the internal thermal stress of the chip 2 when the temperature changes. Example 5

[0036] This embodiment is a further optimization based on embodiment 4.

[0037] See Figures 2 to 4 The first molding compound 1, the chip 2, the second molding compound 7, and the heat sink 8 together form a receiving cavity. The receiving cavity contains a filling material 13. The thermal conductivity of the filling material 13 is lower than that of the heat sink 8 and the detection plate 10. The filling material 13 is a phase change material, which is used to provide support for the chip 2 when it is not working. The material of the filling material 13 can be determined according to its actual required phase change temperature, so that the filling material 13 has changed from solid to liquid before the detection plate 10 and the abutment strip 11 expand. The filling material 13 can be a paraffin-based composite material, so that the filling material 13 has non-conductive properties.

[0038] The above setup enables the chip 2 to be wrapped with the filling material 13. On the one hand, it provides support for the chip 2 when it is not in operation, resisting impacts. On the other hand, it can absorb and contain some heat when the chip 2 is working, and keep the chip 2 warm after it stops working, so that the chip 2 can quickly reach the normal working temperature after restarting. At the same time, the filling material 13 absorbs the heat emitted by the chip 2 when it is initially working, so that the chip 2 gradually heats up, reducing the risk of thermal shock.

[0039] See Figures 2 to 4 An elastic cylinder 14 is fixed to the inner side of the second encapsulation body 7. The elastic cylinder 14 is located between the filler material 13 and the second encapsulation body 7. The elastic cylinder 14 is used to provide space for the expansion of the filler material 13, the detection plate 10 and the abutment strip 11. Example 6

[0040] This embodiment provides a packaging process for a fan-out chip, used to produce the aforementioned fan-out chip packaging structure. See [link to documentation]. Figures 1 to 5 The encapsulation process includes the following steps: Step 1: Fabricate copper pillars 3 on the working surface of chip 2 of the wafer, and perform thinning and cutting of the wafer to meet the packaging size and performance requirements; Step 2: Obtain the parameter information of chip 2, and according to the parameter information of chip 2, carve a groove on the surface of the temporary carrier board that is large enough to accommodate chip 2. Apply an adhesive layer in the groove to provide basic support for the subsequent fixation of chip 2. Step 3: After rigorously testing chip 2 to ensure its performance meets the standards, place chip 2 with its working surface facing up precisely in the groove of the temporary carrier board, so that the working surface of chip 2 is coplanar with the temporary carrier board. Step 4: Using EMC material, a reconstruction wafer is fabricated through a molding process and then cured to form the first molding compound 1; Step 5: Grind the first molding compound 1 to precisely expose the copper pillar 3. Create the redistribution layer 4 and UBM pad 5 on the exposed copper pillar 3. Create solder joints 6 on the UBM pad 5. Step 6: Fabricate heat sink 8, connecting strip 9, detection plate 10, abutment strip 11 and fins 12, and use the phase change characteristics of filling material 13 to connect heat sink 8, connecting strip 9, detection plate 10, abutment strip 11 and fins 12 with filling material 13 and elastic cylinder 14 into one piece in the mold. Step 7: Remove the temporary carrier board and adhesive layer, and use the filler material 13 to fix the positions of the chip 2, heat sink 8, connecting strip 9, detection board 10, abutment strip 11, fin 12, filler material 13 and elastic cylinder 14 on the chip 2. Step 8: Using EMC material, a reconstruction wafer is fabricated through a molding process, and then cured to form a second molding compound 7. The second molding compound 7 is then thinned and cut.

[0041] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A fan-out chip packaging structure, characterized in that, include: A first molding compound (1) has a chip (2) fixedly attached to one side. Multiple copper pillars (3) electrically connected to the chip (2) are fixedly attached inside the first molding compound (1). A redistribution layer (4) is provided on the other side of the first molding compound (1). All the copper pillars (3) are electrically connected to the redistribution layer (4). UBM pads (5) are provided on the redistribution layer (4). Multiple solder joints (6) are provided on the side of the UBM pads (5) away from the chip (2). The solder joints (6) are connected to the redistribution layer (4) through the UBM pads (5). Electrical connection: A second molding body (7) is fixed to the side of the first molding body (1) near the chip (2). A heat sink (8) is fixed inside the second molding body (7). Two symmetrically distributed connecting strips (9) are fixed to the side of the heat sink (8) near the chip (2). The two connecting strips (9) are fixed together to a detection plate (10) that is in contact with the chip (2). A plurality of equally spaced abutment strips (11) are fixed to the side of the detection plate (10) near the heat sink (8). The abutment strips (11) are used to contact the heat sink (8) after thermal expansion.

2. The fan-out chip packaging structure according to claim 1, characterized in that, The heat sink (8) has multiple fins (12) fixed to the side away from the chip (2). The fins (12) are used to increase the area of ​​heat exchange between the heat sink (8) and the outside world.

3. The fan-out chip packaging structure according to claim 2, characterized in that, From the middle of the detection plate (10) toward the connecting strips (9) on both sides, the thickness of all the abutment strips (11) decreases step by step, so as to control the sum of the contact areas of all the abutment strips (11) and the heat sink (8) according to the temperature of the detection plate (10).

4. The fan-out chip packaging structure according to claim 3, characterized in that, From the middle of the detection plate (10) toward the connecting strips (9) on both sides, the distance between two adjacent fins (12) gradually decreases.

5. The fan-out chip packaging structure according to claim 4, characterized in that, The connecting strip (9) is made of elastic material, which allows the distance between the detection plate (10) and the heat sink (8) to change.

6. The fan-out chip packaging structure according to claim 5, characterized in that, The cross-section of the connecting strip (9) is arc-shaped.

7. A fan-out chip packaging structure according to claim 6, characterized in that, The first molding compound (1), the chip (2), the second molding compound (7) and the heat sink (8) together form a cavity, and the cavity contains a filling material (13). The thermal conductivity of the filling material (13) is lower than that of the heat sink (8) and the detection plate (10).

8. The fan-out chip packaging structure according to claim 7, characterized in that, The filling material (13) is a phase change material used to provide support for the chip (2) when the chip (2) is not working.

9. A fan-out chip packaging structure according to claim 8, characterized in that, An elastic cylinder (14) is fixed to the inner side of the second encapsulation body (7). The elastic cylinder (14) is used to provide space for the expansion of the filling material (13), the detection plate (10) and the abutment strip (11).

10. A packaging process for a fan-out chip, wherein the fan-out chip packaging structure according to claim 9 is characterized in that, Includes the following steps: Step 1: Fabricate copper pillars (3) on the working surface of the chip (2) of the wafer, and perform thinning and cutting of the wafer to meet the packaging size and performance requirements; Step 2: Obtain the parameter information of chip (2), and according to the parameter information of chip (2), carve a groove on the surface of the temporary carrier board that is large enough to accommodate chip (2), and coat the groove with an adhesive layer to provide basic support for the subsequent fixation of chip (2). Step 3: After rigorously testing the chip (2) to ensure that its performance meets the standards, place the chip (2) with its working surface facing up precisely in the groove of the temporary carrier board so that the working surface of the chip (2) is coplanar with the temporary carrier board. Step 4: Using EMC material, a reconstructed wafer is fabricated through a molding process and then cured to form the first molding compound (1). Step 5: Grind the first molding compound (1) to precisely expose the copper pillar (3), and make a redistribution layer (4) and UBM pads (5) on the exposed copper pillar (3). Make solder joints (6) on the UBM pads (5). Step 6: Fabricate heat sink (8), connecting strip (9), detection plate (10), abutment strip (11) and fins (12), and use the phase change characteristics of filling material (13) to connect heat sink (8), connecting strip (9), detection plate (10), abutment strip (11) and fins (12) with filling material (13) and elastic cylinder (14) into one piece in the mold; Step 7: Remove the temporary carrier board and adhesive layer, and use the filler material (13) to fit onto the chip (2) to fix the positions of the chip (2), heat sink (8), connecting strip (9), detection board (10), abutment strip (11), fins (12), filler material (13) and elastic cylinder (14); Step 8: Using EMC material, a reconstructed wafer is made through a molding process and then cured to form a second molding compound (7). The second molding compound (7) is then thinned and cut.

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