Flip chip package with improved thermal performance

Abstract

A flip chip package (200) is provided, wherein the flip chip package comprises: at least one chip (202) for connecting to a substrate (201); a molding member (209) formed on the substrate (201) to wrap the side portion of the at least one chip (202) and expose the top surface of each chip (202), wherein the upper surface of the molding member (209) has a first area continuous with the top surface of each chip (202), a second area on which an adhesive (210) is applied, and a top surface disposed to surround each chip (202). A wall-like structure (209a) is formed on the surface of the heat sink (206), and the first area and the second area are separated by the wall-like structure (209a); a heat sink (206) is placed above the top surface of each chip (202) and bonded to the molded member (209) by an adhesive (210) filled in the second area; a thermal interface material (205), the thermal interface material (205) is filled in a space area formed by the first area, the top surface of each chip (202), at least a portion of the bottom surface of the heat sink (206) and the first side of the wall-like structure (209a).

Description

Technical Field

[0001] The present invention relates to a flip chip package with improved thermal performance, a device equipped with a circuit applying the flip chip package structure, and a method of assembling the flip chip package. Background Art

[0002] Recent advances in semiconductor packaging in terms of processing performance have placed higher demands on thermal performance to ensure stable operation. In this regard, flip-chip packaging has advantages in terms of thermal performance because its structural feature is that the chip is connected to the substrate through bumps underneath it, and the heat sink can be positioned on the top surface of the chip.

[0003] To improve cooling performance, a thermal interface material (TIM) such as thermal grease is applied to the top surface of the chip and sandwiched between the chip and at least a portion of the heat sink. From the perspective of reducing thermal resistance in the TIM to improve the thermal performance of the package, it is preferred to make the TIM thinner.

[0004] U.S. Patent No. 8,368,194 proposes a flip chip package with a heat sink, the heat sink comprising a flat cover and a side wall extending downward from the end of the flat cover. In the proposed package, the distance between the flat cover and the substrate on which the chip is disposed is defined by the height of the side wall in the heat sink made of solid metal. In this case, the thickness of the TIM is defined by the distance between the bottom surface of the flat cover and the top surface of the chip on the substrate, so that the thickness of the TIM is also defined by the height of the side wall. Therefore, it is difficult to finely control the thickness of the TIM during the assembly process of the proposed package. This means that in some cases, it may be difficult for the proposed package to achieve a small thickness of the TIM to obtain a higher thermal performance sufficient to ensure stable operation.

[0005] Furthermore, when assembling the proposed package, the difference in thermal expansion coefficients between the heat sink, substrate, and chip causes the gap between the chip and the flat cover (hereinafter referred to as "TIM gap") to expand. The expansion of the TIM gap may cause the TIM to delaminate from the heat sink. The delamination of the TIM may reduce thermal performance and increase the junction temperature during operation, resulting in reduced reliability. As described above, the proposed package has problems to be solved in achieving higher thermal performance sufficient to ensure stable operation.

[0006] Desmond YRChong et al., in "Development of a New and Improved High-Performance Flip-Chip BGA Package" (Electronic Components and Technology Conference, 2004, pp. 1174-1180), proposed a flip-chip package having structural features for reducing the expansion of the TIM gap during the reflow process. The proposed package has a molding member formed on a substrate and bonded by an adhesive applied to the upper surface of the molding member. The molding member can act as a support member to physically maintain the gap between the heat sink and the substrate, thereby reducing the expansion of the TIM gap during the reflow process.

[0007] However, the proposed package lacks a structure for controlling the TIM thickness and / or the TIM gap size, and thus it is difficult to finely control the TIM gap to achieve a small thickness of the TIM, thereby obtaining a higher thermal performance sufficient to ensure stable operation. In addition, the TIM of the proposed package may contact the adhesive applied to the upper surface of the molding member, and during the reflow process, at least a portion of the TIM may flow into the adhesive and / or at least a portion of the adhesive may flow into the TIM.

[0008] If the TIM flows into the adhesive during the reflow process, voids will be generated in the TIM, resulting in an increase in thermal resistance in the TIM. In addition, if the adhesive flows into the TIM during the reflow process, the effective volume of the TIM will be reduced, resulting in an increase in thermal resistance in the TIM. The increase in thermal resistance in the TIM will in turn lead to a decrease in thermal performance. As described above, the proposed package has problems to be solved in achieving higher thermal performance sufficient to ensure stable operation. Summary of the invention

[0009] Embodiments of the present invention provide a flip chip package, a device equipped with a circuit applying the package structure, and a method for assembling the package.

[0010] For example, the circuit packaged by the application may be a processing circuit, such as a central processing unit (CPU), a field-programmable gate array (FPGA), an application specific integrated circuit (ASIC), a graphics processing unit (GPU), etc. In addition, the circuit packaged by the application may be a communication circuit, such as a high-frequency circuit for a wired communication interface, a wireless communication interface, an optical communication interface, a network switch, etc. In addition, the circuit packaged by the application may be a power control circuit, such as a power control unit for a vehicle, an energy management system, etc.

[0011] The device may be a mobile device such as a mobile phone, a smart phone, a tablet computer, a wearable computer, etc. In addition, the device may be a computer such as a personal computer, a workstation, a server, an artificial intelligence (AI) cluster, a cloud computing system, an Internet of Things (IoT) device, etc. In addition, the device may be a camera such as a digital still camera, a digital camera, a security / surveillance camera, a network camera, a video camera, an automotive / transportation camera, a medical camera, a machine vision, etc. Alternatively, the device may be a component including the above circuit, such as a module or an electronic unit in a computer or a computing system.

[0012] In the following, modifiers such as "top", "bottom", "up", "down", "upward", and "downward" may be used, but these modifiers only indicate relative positional relationships in their target elements and do not point to any specific direction relative to the ground. For example, the top surface of a chip may refer to the front surface of the chip facing the heat sink in a flip-chip package, and the bottom surface of the chip may refer to the reverse surface of the chip facing the substrate in the package.

[0013] A first aspect of an embodiment of the present invention provides a flip chip package. In a first possible implementation of the first aspect, the package includes:

[0014] at least one chip, used to connect to the substrate;

[0015] a molding member formed on the substrate to wrap a side portion of the at least one chip and to expose a top surface of each chip, the upper surface of the molding member having a first region continuous with the top surface of each chip, a second region to which an adhesive is applied, and a wall-like structure placed to surround the top surface of each chip, the first region and the second region being separated by the wall-like structure;

[0016] a heat sink placed over the top surface of the at least one chip and bonded to the molding member by an adhesive applied to the second region;

[0017] A thermal interface material is filled in a space region formed by the first region, the top surface of each chip, at least a portion of the bottom surface of the heat sink, and the first side of the wall-like structure.

[0018] Alternatively, the heat sink may be made of Cu, Ag-diamond or Co-Mo. Using a heat sink made of a lower coefficient of thermal expansion (CTE) material can reduce the stress on the thermal interface material during the reflow process.

[0019] According to a first possible implementation of the first aspect, the thermal interface material is formed in a spatial region surrounded by the top surface of each chip, the bottom surface of the heat sink, the first region of the molding member, and one side of the wall-like structure in the molding member. Therefore, the thickness of the thermal interface material is defined by the height of the wall-like structure in the molding member. Since the height of the wall-like structure composed of the mold compound can be easily controlled during the molding process, the thickness of the thermal interface material can be adjusted to a desired small thickness, thereby achieving improved thermal performance.

[0020] In addition, in a first possible implementation of the first aspect, the first area and the second area of ​​the molded member are spatially separated by a wall-like structure, thereby avoiding mixing of the thermal interface material applied to the first area and the adhesive applied to the second area during the reflow process. This can avoid the formation of voids in the thermal interface material and prevent the thermal interface material from flowing out into the adhesive, thereby improving thermal performance. In addition, the molded member can be used as a supporting member to maintain the distance between the bottom of the heat sink and the substrate, thereby reducing the risk of delamination of the thermal interface material from the heat sink during the reflow process. For the above reasons, the package according to the first possible implementation of the first aspect can achieve improved thermal performance, thereby ensuring sufficient operational reliability.

[0021] A second possible implementation manner of the first aspect provides the package according to the first possible implementation manner of the first aspect, wherein the package further includes:

[0022] A reinforcement member having a square frame-like structure is formed on a substrate to surround the outside of a molding member, and the molding member is formed to fill an inner region of the reinforcement member.

[0023] According to a second possible implementation manner of the first aspect, the reinforcement member can enhance the strength of the package, thereby increasing the resistance of the package to external impact.

[0024] A third possible implementation manner of the first aspect provides the package according to the first possible implementation manner of the first aspect, wherein:

[0025] The heat sink has a cover portion placed over the at least one chip and a side portion extending downward from an end of the cover portion, the side portion is placed outside the molding member, and the end of the side portion is bonded to a substrate by an adhesive.

[0026] According to a third possible implementation of the first aspect, the side portion of the heat sink can enhance the strength of the package, thereby increasing the resistance of the package to external impact. In addition, the structure of the heat sink with the side portion can ensure that there is a large area for heat dissipation to improve cooling efficiency, thereby improving its thermal performance.

[0027] Optionally, according to any one of the first to third possible implementations of the first aspect, in the package, the second region includes an adhesive pool for filling the adhesive, wherein the second side of the wall-like structure forms at least a portion of one side of the adhesive pool.

[0028] Optionally, according to any one of the first to fifth possible implementations of the first aspect, in the package, the height of the wall-like structure can be controlled to be about 200 μm or less, and the width thereof can also be controlled to be about 3.0 mm or less.

[0029] Optionally, according to any one of the first to third possible implementation methods of the first aspect, in the package, the thermal interface material can be composed of organic-based materials (such as silicon, etc.), metals (such as InSn, InAg, etc.), Ag sintered materials (such as nano-Ag, etc.) or carbon nanotube (carbon nanotube, CNT)-based materials, etc.

[0030] A second aspect of an embodiment of the present invention provides the device. In a first possible implementation of the second aspect, the device includes a circuit composed of a flip chip package, and the flip chip package includes:

[0031] at least one chip, used to connect to the substrate;

[0032] a molding member formed on the substrate to wrap a side portion of the at least one chip and to expose a top surface of each chip, the upper surface of the molding member having a first region continuous with the top surface of each chip, a second region to which an adhesive is applied, and a wall-like structure placed to surround the top surface of each chip, the first region and the second region being separated by the wall-like structure;

[0033] a heat sink placed over the top surface of the at least one chip and bonded to the molding member by an adhesive applied to the second region;

[0034] A thermal interface material is filled in a space region formed by the first region, the top surface of each chip, at least a portion of the bottom surface of the heat sink, and the first side of the wall-like structure.

[0035] Alternatively, the heat sink may be made of Cu, Ag-diamond, or Co-Mo. Using a heat sink made of a lower CTE material may reduce stress on the thermal interface material during the reflow process.

[0036] According to a first possible implementation of the second aspect, the thermal interface material is formed in a spatial region surrounded by the top surface of each chip, the bottom surface of the heat sink, the first region of the molding member, and one side of the wall-like structure in the molding member. Therefore, the thickness of the thermal interface material is defined by the height of the wall-like structure in the molding member. Since the height of the wall-like structure composed of the mold compound can be easily controlled during the molding process, the thickness of the thermal interface material can be adjusted to a desired small thickness, thereby achieving improved thermal performance.

[0037] In addition, in a first possible implementation of the second aspect, the first area and the second area of ​​the molded member are spatially separated by a wall-like structure, thereby avoiding mixing of the thermal interface material applied to the first area and the adhesive applied to the second area during the reflow process. This can avoid the formation of voids in the thermal interface material and prevent the thermal interface material from flowing out into the adhesive, thereby improving thermal performance. In addition, the molded member can be used as a supporting member to maintain the distance between the bottom of the heat sink and the substrate, thereby reducing the risk of delamination of the thermal interface material from the heat sink during the reflow process. For the above reasons, the package according to the first possible implementation of the second aspect can achieve improved thermal performance, thereby ensuring sufficient operational reliability, so that stable operation of the device can be achieved even in a high-load environment.

[0038] A second possible implementation manner of the second aspect provides the device according to the first possible implementation manner of the second aspect, wherein the package further includes:

[0039] A reinforcement member having a square frame-like structure is formed on a substrate to surround the outside of a molding member, and the molding member is formed to fill an inner region of the reinforcement member.

[0040] According to a second possible implementation manner of the second aspect, the reinforcement member can enhance the strength of the package, thereby increasing the resistance of the device to external impact.

[0041] A third possible implementation manner of the second aspect provides the device described in the first possible implementation manner of the second aspect, wherein:

[0042] The heat sink has a cover portion placed over the at least one chip and a side portion extending downward from an end of the cover portion, the side portion is placed outside the molding member, and the end of the side portion is bonded to a substrate by an adhesive.

[0043] According to a third possible implementation of the second aspect, the side portion of the heat sink can enhance the strength of the package, thereby increasing the resistance of the device to external impact. In addition, the structure of the heat sink with the side portion can ensure that there is a large area for heat dissipation to improve cooling efficiency, thereby improving its thermal performance. This helps the device to operate stably in a high-load environment.

[0044] Optionally, according to any one of the first to third possible implementations of the second aspect, in the device, the second region includes an adhesive pool for filling the adhesive, wherein the second side of the wall-like structure forms at least a portion of one side of the adhesive pool.

[0045] Optionally, according to any one of the first to third possible implementations of the second aspect, in the device, the height of the wall-like structure can be controlled to be about 200 μm or less, and the width thereof can also be controlled to be about 3.0 mm or less.

[0046] Optionally, according to any one of the first to third possible implementation methods of the second aspect, in the device, the thermal interface material can be composed of organic-based materials (such as silicon, etc.), metals (such as InSn, InAg, etc.), Ag sintered materials (such as nano-Ag, etc.) or CNT-based materials, etc.

[0047] A third aspect of an embodiment of the present invention provides a method for assembling a flip chip package, the flip chip package comprising at least one chip, a substrate, a molding component, a thermal interface material, and a heat sink. In a first possible implementation of the third aspect, the method comprises:

[0048] connecting the at least one chip to the substrate;

[0049] filling a mold compound around the at least one chip on the substrate to wrap a side portion of the at least one chip and expose a top surface of each chip, and molding the molding member in a structure in which an upper surface of the molding member has a first region continuous with the top surface of each chip, a second region to which an adhesive is applied, and a wall-like structure disposed to surround the top surface of each chip, and the first region and the second region are separated by the wall-like structure;

[0050] applying the adhesive to a second region of the molding member;

[0051] Applying thermal interface material on the first area and the top surface of each chip;

[0052] connecting the heat sink to the thermal interface material and the molding member via the adhesive;

[0053] A reflow process of the package is performed.

[0054] According to a first possible implementation of the third aspect, the thermal interface material is formed in a spatial region surrounded by the top surface of each chip, the bottom surface of the heat sink, the first region of the molding member, and one side of the wall-like structure in the molding member. Therefore, the thickness of the thermal interface material is defined by the height of the wall-like structure in the molding member. Since the height of the wall-like structure composed of the mold compound can be easily controlled during the molding process, the thickness of the thermal interface material can be adjusted to a desired small thickness, thereby achieving improved thermal performance.

[0055] In addition, in a first possible implementation of the third aspect, the first area and the second area of ​​the molded member are spatially separated by a wall-like structure, thereby avoiding mixing of the thermal interface material applied to the first area and the adhesive applied to the second area during the reflow process. This can avoid the formation of voids in the thermal interface material and prevent the thermal interface material from flowing out into the adhesive, thereby improving thermal performance. In addition, the molded member can be used as a supporting member to maintain the distance between the bottom of the heat sink and the substrate, thereby reducing the risk of delamination of the thermal interface material from the heat sink during the reflow process. For the above reasons, the package according to the first possible implementation of the first aspect can achieve improved thermal performance, thereby ensuring sufficient operational reliability.

[0056] A second possible implementation manner of the third aspect provides the method of the first possible implementation manner of the third aspect, wherein:

[0057] Before filling the mold compound, the method further includes forming a stiffener on the substrate, the stiffener having a square frame-like structure for surrounding an entire area on which the at least one chip is disposed, and the molding member is formed to fill an inner area of ​​the stiffener.

[0058] According to a second possible implementation manner of the third aspect, the reinforcement member can enhance the strength of the package, thereby increasing the resistance of the package to external impact.

[0059] A third possible implementation of the third aspect provides the method according to the first possible implementation of the third aspect, wherein the heat sink has a cover portion placed above the at least one chip and a side portion extending downward from an end of the cover portion, and the side portion is placed outside the molding member,

[0060] When the heat sink is attached, the end portions of the side portions are adhered to the substrate by an adhesive.

[0061] According to a third possible implementation of the third aspect, the side portion of the heat sink can enhance the strength of the package, thereby increasing the resistance of the package to external impact. In addition, the structure of the heat sink with the side portion can ensure that there is a large area for heat dissipation to improve cooling efficiency, thereby improving its thermal performance.

[0062] Optionally, according to any one of the first to third possible implementations of the third aspect, in the method, the molding can be implemented by transfer molding or compression molding.

[0063] Optionally, according to any one of the first to third possible implementations of the third aspect, in the method, the height of the wall-like structure can be controlled to be about 200 μm or less, and the width thereof can also be controlled to be about 3.0 mm or less.

[0064] Optionally, according to any one of the first to third possible implementation methods of the third aspect, in the method, the thermal interface material can be composed of organic-based materials (such as silicon, etc.), metals (such as InSn, InAg, etc.), Ag sintered materials (such as nano-Ag, etc.) or CNT-based materials, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 is a schematic block diagram for describing an exemplary configuration of an apparatus according to an embodiment of the present invention,

[0066] Figure 2 is a schematic cross-sectional view of a flip chip package according to an embodiment of the present invention,

[0067] Figure 3 According to an embodiment of the present invention, Figure 2 A magnified view of a flip chip package.

[0068] Figure 4 According to an embodiment of the present invention, Figure 2 Schematic top view of a flip chip package,

[0069] Figures 5A to 5E According to an embodiment of the present invention, there is described Figure 2 Schematic diagram of the assembly process of flip chip packaging,

[0070] Figure 6 An embodiment according to the present invention is shown. Figure 2 Simulation results of gap variation during assembly of flip chip package,

[0071] Figure 7 FIG. 1 shows a first exemplary variation of a flip chip package according to an embodiment of the present invention.

[0072] Fig. 8A and 8B FIG. 4 shows a packaging structure in a second exemplary variation of a flip chip package according to an embodiment of the present invention.

[0073] Fig.9A and 9B FIG. 4 shows a packaging structure in a third exemplary variation of a flip chip package according to an embodiment of the present invention.

[0074] Fig. 10A and 10B FIG. 4 shows a packaging structure in a fourth exemplary variation of a flip chip package according to an embodiment of the present invention.

[0075] Figures 11A to 11F is a schematic top view of a flip chip package according to an embodiment of the present invention, for describing some possible shapes of a molding member therein,

[0076] Fig. 12A and 12B shows possible variations of flip chip packaging according to an embodiment of the present invention,

[0077] 13A and 13B show an example of a conventional flip chip package. DETAILED DESCRIPTION

[0078] The technical scheme of the embodiment is described below with reference to the accompanying drawings. It is understood that the embodiments described below are not all embodiments, but only some embodiments related to the present invention. It should be noted that other embodiments that can be derived based on the embodiments described below by those skilled in the art without paying creative labor are within the scope of protection of the present invention.

[0079] (Conventional Flip Chip Package) Before describing the embodiment of the present invention, let us introduce conventional flip chip packaging and its problems with reference to Figures 13A and 13B. Figures 13A and 13B show an example of conventional flip chip packaging.

[0080] Fig. 13A schematically shows a cross-sectional view of a first conventional flip chip package. As shown in Fig. 13A, the first conventional flip chip package includes a substrate, a chip, an underfill, a thermal interface material (TIM), and a heat sink.

[0081] The chip is connected to the substrate through a bump below the chip, and the bottom area of ​​the chip is filled with the bottom filler. The heat sink has a flat cover and a side wall extending downward from the end of the flat cover. The flat cover of the heat sink is used to make the bottom surface of the flat cover parallel to the top surface of the chip. The side wall of the heat sink is placed to surround the chip and is bonded to the substrate by applying an adhesive to one end of the side wall.

[0082] The TIM is sandwiched between at least a portion of the bottom surface of the flat cover of the heat sink and the top surface of the chip. Hereinafter, the gap between the heat sink and the chip where the TIM is applied may be referred to as a TIM gap. From the perspective of reducing the thermal resistance between the chip and the heat sink, it is preferred to make the thickness of the TIM smaller.

[0083] In the first conventional flip chip package, the TIM gap is defined by the height of the sidewall in the heat sink, making it difficult to fine-tune the height to achieve a small TIM gap (e.g., about 200 μm or less). This means that it is difficult to achieve a small thickness of the TIM in the first conventional flip chip package. In addition, the difference in thermal expansion coefficients between the heat sink, the substrate, and the chip causes the TIM gap to expand during the reflow process when assembling the flip chip package, thereby promoting delamination of the TIM from the heat sink. Delamination of the TIM reduces thermal performance and increases junction temperature during operation, resulting in reduced reliability of the flip chip package.

[0084] In order to reduce the expansion of the TIM gap during the reflow process, a second conventional flip chip package is proposed, which has a molding member (mold) surrounding the chip as shown in FIG. 13B. The molding member is formed on a substrate and bonded by an adhesive applied to the upper surface of the molding member. In the second conventional flip chip package, the molding member can act as a supporting member to physically maintain the gap between the heat sink and the substrate, thereby reducing the expansion of the TIM gap during the reflow process.

[0085] However, the second conventional flip chip package lacks a member that physically defines the TIM thickness or the TIM gap size, so it is difficult to control the TIM gap to achieve a small thickness of the TIM (e.g., about 200 μm or less). Even if the heat sink of the first conventional flip chip package can be applied to the second conventional flip chip package, this problem still exists.

[0086] Furthermore, in the second conventional flip chip package, the TIM is in contact with the adhesive on the molding member, so that during the reflow process, a portion of the TIM flows into the adhesive and / or a portion of the adhesive flows into the TIM. If a portion of the TIM flows into the adhesive during the reflow process, a void will be formed in the TIM, resulting in an increase in the thermal resistance of the TIM. If a portion of the adhesive flows into the TIM during the reflow process, the effective volume of the TIM will be reduced, resulting in an increase in the thermal resistance in the TIM. The increase in the thermal resistance in the TIM will in turn lead to a decrease in thermal performance during operation.

[0087] For the above reasons, the embodiments of the present invention described below provide solutions to the problems of conventional flip chip packaging of the above first and second conventional flip chip packages. Embodiments of the present invention relate to flip chip packaging, devices equipped with circuits applying the packaging structure, and methods of assembling the packaging.

[0088] (Exemplary Configuration of Apparatus) An exemplary configuration of an apparatus according to an embodiment of the present invention is described below.

[0089] Figure 1 is a schematic block diagram for describing an exemplary configuration of an apparatus according to an embodiment of the present invention.

[0090] Figure 1 The device 10 in the figure is an example of a device according to an embodiment of the present invention. For example, the device 10 may be a mobile device such as a mobile phone, a smart phone, a tablet computer, a wearable computer, etc. In addition, the device 10 may be a computer such as a personal computer, a workstation, a server, an AI cluster, a cloud computing system, an IoT device, etc. Alternatively, the device 10 may be a camera such as a digital still camera, a digital camera, a security / surveillance camera, a network camera, a video camera, an automotive / transportation camera, a medical camera, a machine vision camera, etc.

[0091] like Figure 1 As shown, the device 10 includes a processing circuit 11 and a communication circuit 12. For example, the processing circuit 11 may include at least one processor such as a CPU, an FPGA, an ASIC, a GPU, etc. The communication circuit 12 may include at least one high-frequency circuit for a wired communication interface, a wireless communication interface, an optical communication interface, a network switch, etc. Optionally, the device 10 may also include a power control circuit for a vehicle, an energy management system, etc.

[0092] Each of the processing circuit 11, the communication circuit 12, and the power control circuit is an example of a circuit to which the flip chip package according to the embodiments of the present invention can be applied. The configuration of the device 10 described herein is exemplary, and the scope of application of the embodiments of the present invention is not limited thereto.

[0093] (Structure of Flip Chip Package) The following describes the structure of a flip chip package according to an embodiment of the present invention.

[0094] Figure 2 is a schematic cross-sectional view of a flip chip package according to an embodiment of the present invention. Figure 2 The flip chip package 200 is an example of a flip chip package according to an embodiment of the present invention.

[0095] like Figure 2 As shown, package 200 includes substrate 201, semiconductor chip (die) 202, bump 203, bottom filler 204, thermal interface material (TIM) 205, heat sink 206, reinforcement 207 and molding member 209. Molding member 209 is composed of mold compound. TIM 205 can be composed of organic-based materials (such as silicon, etc.), metals (such as InSn, InAg, etc.), Ag sintered materials (such as nano-Ag, etc.) or CNT-based materials, etc.

[0096] The reinforcement 207 is bonded to the substrate 201 by an adhesive 208. The heat sink 206 is bonded to the molding member 209 by an adhesive 210. In this example, the adhesive 210 is also filled in a region formed by the heat sink 206 and one side of the molding member 209, thereby enhancing their adhesion.

[0097] The chip 202 is connected to the substrate 201 through bumps 203 sandwiched between the upper surface of the substrate 201 and the bottom surface of the chip 202. The molding member 209 is formed on the substrate 201 to wrap the side portion of the chip 202 and leave the top surface of the chip 202 exposed.

[0098] The upper surface of the molding member 209 has a first region continuous with the top surface of the chip 202 , a second region where the adhesive 210 is applied, and a wall-like structure 209 a .

[0099] The wall structure 209a is Figure 3 The raised portion shown has a width W and a height H. Figure 3 According to an embodiment of the present invention, Figure 2 A partial enlarged view of a flip chip package. For example, the width W can be controlled to be about 3.0 mm or less, and the height H can be controlled to be about 200 μm or less. These configurations are only examples, so the width W and the height H can be set to values ​​other than the above values.

[0100] In addition, if Figure 4 As shown, a wall-like structure 209 a is placed around the top surface of the chip 202 . Figure 4 According to an embodiment of the present invention, Figure 2Schematic top view of a flip chip package. Figure 4 For simplicity, the heat sink 206 is omitted, and the II-II cutting line corresponds to Figure 2 A cross-sectional view of the Figure 4 As shown, TIM 205 is filled in the inner region surrounded by wall-like structure 209a, and adhesive 210 is applied to the region (second region) outside wall-like structure 209a. In this example, the second region acts as an adhesive pool for filling adhesive 210.

[0101] exist Figure 2 In the embodiment, the first area of ​​the upper surface of the molding member 209 is a flat portion close to the chip 202 and extends from the inner wall of the wall-like structure 209a to the edge of the chip 202. The second area of ​​the molding member 209 extends outward from the outer wall of the wall-like structure 209a. Here, the modifiers "inner" and "outer" respectively refer to one side closer to the center of the chip 202 and the other side closer to the edge of the package 200.

[0102] The heat sink 206 is placed above the top surface of the chip 202 and is bonded to the molding member 209 by the adhesive 210 applied to the second area. The heat sink 206 can be made of a low CTE material such as Cu, Ag-diamond, or Co-Mo. During the assembly process of the package 200, the use of the heat sink 206 made of a low CTE material can reduce the stress on the TIM 205 during the reflow process.

[0103] like Figure 2 As shown, the heat sink 206 is supported by the wall structure 209a, and the first area and the second area of ​​the upper surface of the molding member 209 are spatially separated by the wall structure 209a. This structure can prevent the TIM 205 applied to the first area and the adhesive 210 applied to the second area from mixing during the reflow process, thereby preventing the formation of voids in the TIM 205 and preventing the TIM 205 from flowing out into the adhesive 210.

[0104] The TIM 205 is filled in a space region formed by the top surface of the chip 202, the bottom surface of the heat sink 206, the first region of the molding member 209, and the inner wall of the wall-like structure 209a. Figure 3 As shown, the thickness of the TIM 205 is defined by the height H of the wall-like structure 209 a.

[0105] The reinforcing member 207 has a square frame-like structure and is formed on the substrate 201 to surround the outer side of the molding member 209, such as Figure 4 In addition, the molding member 209 is formed to fill the inner area of ​​the reinforcement member 207. The reinforcement member 207 can enhance the strength of the package 200, thereby increasing the resistance of the package 200 to external impact.

[0106] As described above, in the package 200, the TIM 205 is formed in a spatial region surrounded by the top surface of the chip 202, at least a portion of the bottom surface of the heat sink 206, the first region of the molding member 209, and one side of the wall-like structure 209a. Therefore, the thickness of the TIM 205 is defined by the height H of the wall-like structure 209a, and the height H can be easily controlled during the molding process. This means that the thickness of the TIM 205 can be fine-tuned to a desired small thickness (e.g., about 200 μm or less) to achieve improved thermal performance.

[0107] In addition, the first and second regions of the molding member 209 are spatially separated by the wall-like structure 209a, thereby preventing the TIM 205 and the adhesive 210 from mixing during the reflow process. This can prevent the formation of voids in the TIM 205 and prevent the TIM 205 from flowing out into the adhesive 210, thereby improving thermal performance. In addition, the molding member 209 can act as a supporting member to maintain the distance between the heat sink 206 and the substrate 201, thereby reducing the risk of the TIM 205 being delaminated from the heat sink 206 during the reflow process.

[0108] For the reasons described above, the package 200 can achieve improved thermal performance, thereby ensuring sufficient operational reliability.

[0109] (Assembly Process of Package) The following describes an assembly method of a flip chip package according to an embodiment of the present invention.

[0110] Figures 5A to 5E Is used to describe Figure 2 Schematic diagram of the assembly process of package 200.

[0111] like Figure 5A As shown, the chip 202 is placed on the substrate 201 to sandwich the bumps 203 between the bottom surface of the chip 202 and the substrate 201. In addition, the stiffener 207 is placed on the substrate 201 to sandwich the adhesive 208 between the bottom surface of the stiffener 207 and the substrate 201.

[0112] Next, if Figure 5B As shown, the bottom filler 204 is filled in the area under the chip 202 to cover the bump 203, wherein the bottom filler 204 may cover a portion of the sidewall of the chip 202. The bottom filler 204 is solidified after filling.

[0113] Next, if Figure 5CAs shown, a mold compound is filled around the chip 202 on the substrate 201 to wrap the side portion of the chip 202 and expose the top surface of the chip 202. In addition, molding is performed to form a molding member 209, wherein the upper surface of the molding member 209 has a first area b1, a second area b2, and a wall-like structure 209a. For example, the molding can be implemented using a transfer molding method or a compression molding method.

[0114] The first region b1 is a region continuous with the top surface of the chip 202, and the second region b2 is a region to be applied with the adhesive 210. The wall-like structure 209a is a portion of the molding member 209, which is placed to surround the top surface of the chip 202. The first region b1 and the second region b2 are separated by the wall-like structure 209a. In this example, the second region b2 forms an adhesive pool for filling the adhesive 210.

[0115] Next, if Figure 5D As shown, the adhesive 210 is applied to the second region of the molding member 209. In addition, the TIM 205 is filled in the region surrounded by the first region b1, the wall structure 209a, and the top surface of the chip 202. The TIM 205 and the adhesive 210 are cured after being applied.

[0116] Next, if Figure 5E As shown, heat sink 206 is placed on the exposed portion (top end) of wall structure 209a to seal TIM 205, and adhesive 210 is sandwiched between heat sink 206 and wall structure 209a. After heat sink 206 is attached, a reflow process for connecting chip 202 to substrate 201 is performed.

[0117] During the reflow process, the package 200 is heated to about 250 degrees Celsius. However, since the adhesive 210 applied to the first area b1 and the TIM 205 applied to the second area b2 are spatially separated by the wall structure 209a, the TIM 205 and the adhesive 210 are prevented from mixing during the reflow process. This can prevent the formation of voids in the TIM 205 and prevent the TIM 205 from flowing out into the adhesive 210, thereby improving thermal performance.

[0118] Furthermore, the molding member 209 may serve as a supporting member to maintain a distance between the heat sink 206 and the substrate 201 , thereby reducing the risk of the TIM 205 being delaminated from the heat sink 206 during a reflow process.

[0119] (Gap Variation During Assembly Process) The following describes the variation of the TIM gap during the reflow process.

[0120] Figure 6 An embodiment according to the present invention is shown. Figure 2Simulation results of gap variation during the assembly process of flip chip packaging. Figure 6 In the graph of , the vertical axis and horizontal axis represent TIM interval and time, respectively. Figure 6 Another axis indicating the temperature of the package 200 is shown in FIG. Figure 6 13A , the solid rectangular dots represent data corresponding to the package 200 (embodiment), and the open circles represent data corresponding to the conventional package shown in FIG. 13A .

[0121] At time t1, the temperature is set to approximately 150 degrees Celsius, the temperature at which the adhesive cures. In this example, the package cools to approximately 30 degrees Celsius before time t6, and the temperature is set to approximately 150 degrees Celsius at time t 15 The temperature of the heat sink 206 is gradually increased to about 250 degrees Celsius before assembly reflow. For the conventional package, the TIM gap increases sharply to about 185 μm during the reflow process. In contrast, for package 200, the TIM gap increases gradually but remains below 110 μm, which is significantly smaller than the conventional package. This means that package 200 can reduce the risk of TIM 205 delaminating from heat sink 206 during the reflow process.

[0122] (First Exemplary Modification of Flip Chip Package) A first exemplary modification of the flip chip package according to the embodiment of the present invention is described below.

[0123] Figure 7 A first exemplary variation of a flip chip package according to an embodiment of the present invention is shown. Figure 7 The illustrated flip chip package 300 is an example of a flip chip package according to the first exemplary modification.

[0124] like Figure 7 As shown, package 300 includes substrate 301, semiconductor chip (die) 302, bump 303, underfill 304, TIM 305, heat sink 306, stiffener 307 and molding member 309. Stiffener 307 is bonded to substrate 301 by adhesive 308. Heat sink 306 is bonded to molding member 309 by adhesive 310.

[0125] Package 300 differs from package 200 described above in the structures of heat sink 306 and molding member 309. Specifically, heat sink 306 extends to the outer edge of package 300 and is therefore wider than heat sink 206 of package 200, and molding member 309 also extends below the extended portion of heat sink 306, as shown in FIG. Figure 7 The adhesive 310 is also applied to the extended portion of the molding member 309 and is sandwiched between the heat sink 306 and the wall structure 309a.

[0126] According to the first variation, the cooling performance of the heat sink 306 is improved accordingly due to the enlarged volume of the heat sink 306. In addition, since the adhesion area between the heat sink 306 and the wall structure 309a is extended, the first variation can effectively reduce the risk of TIM 205 delaminating from the heat sink 206 during the reflow process.

[0127] (Second Exemplary Modification of Flip Chip Package) A second exemplary modification of the flip chip package according to the embodiment of the present invention is described below.

[0128] Fig. 8A A package structure in a second exemplary variation of a flip chip package according to an embodiment of the present invention is shown. Figure 8B Another packaging structure in a second exemplary variation of a flip chip package according to an embodiment of the present invention is shown. Fig. 8A or Figure 8B The flip chip package 400 shown in FIG. 4 is an example of a flip chip package according to the second exemplary modification.

[0129] The package 400 includes a substrate 401, a semiconductor chip (die) 402, bumps 403, an underfill 404, a TIM 405, a heat sink 406, and a molding member 409. The heat sink 406 is bonded to the molding member 409 by an adhesive 410. Fig. 8A The package 400 is different from the above-described package 200 in that a member corresponding to the reinforcement 207 is omitted.

[0130] exist Fig. 8A In the package 400 of FIG. 4 , the area where the adhesive 410 is applied has a structure similar to a flat tray on which the adhesive 410 is applied. Figure 8B In the package 400 , the area where the adhesive 410 is applied has a structure similar to a pool filled with the adhesive 410 .

[0131] (Third Exemplary Modification of Flip Chip Package) Next, a third exemplary modification of the flip chip package according to the embodiment of the present invention is described.

[0132] Fig.9A A package structure in a third exemplary variation of a flip chip package according to an embodiment of the present invention is shown. Fig. 9B Another packaging structure in a third exemplary variation of a flip chip package according to an embodiment of the present invention is shown. Fig.9A or Fig. 9B A flip chip package 500 shown in FIG. 5 is an example of a flip chip package according to the third exemplary modification.

[0133] The package 500 includes a substrate 501, a semiconductor chip (die) 502, bumps 503, an underfill 504, a TIM 505, a heat sink 506, a stiffener 507, and a molding member 509. The stiffener 507 is bonded to the substrate 501 by an adhesive 508. The heat sink 506 is bonded to the molding member 509 by an adhesive 510.

[0134] Package 500 differs from package 200 described above in the structures of heat sink 506 and stiffener 507. Specifically, heat sink 506 extends to the outer edge of package 500 and is therefore wider than heat sink 206 of package 200, and stiffener 507 is buried in mold structure 509a, as shown in FIG. Fig.9A and 9B In addition, the molding member 509 covers the upper surface of the reinforcement 507 , and the adhesive 510 is further applied to the portion of the molding member 509 covering the reinforcement 507 .

[0135] exist Fig.9A In the package 500 of FIG. 5 , the area where the adhesive 510 is applied has a structure similar to a flat tray on which the adhesive 510 is applied. Fig. 9B In the package 500 , the area where the adhesive 510 is applied has a structure similar to a pool filled with the adhesive 510 .

[0136] (Fourth Exemplary Modification of Flip Chip Package) A fourth exemplary modification of the flip chip package according to the embodiment of the present invention is described below.

[0137] Fig. 10A A package structure in a fourth exemplary variation of a flip chip package according to an embodiment of the present invention is shown. Fig. 10B Another packaging structure in a fourth exemplary variation of a flip chip package according to an embodiment of the present invention is shown. Fig. 10A or Fig. 10B A flip chip package 600 shown in FIG. 6 is an example of a flip chip package according to a fourth exemplary modification.

[0138] The package 600 includes a substrate 601, a semiconductor chip (die) 602, bumps 603, an underfill 604, a TIM 605, a heat sink 606, and a molding member 609. The heat sink 606 is bonded to the molding member 609 by an adhesive 610, and is also bonded to the substrate 601 by an adhesive 608.

[0139] The package 600 is different from the package 200 described above in that the components corresponding to the reinforcement member 207 and the structure of the heat sink 606 are omitted. Specifically, the heat sink 606 is formed by a flat cover and a side wall extending downward from the end of the flat cover, wherein the flat cover extends to the outer edge of the package 600 and is therefore wider than the heat sink 206 of the package 200. Fig. 10A and 10B shown.

[0140] exist Fig. 10A In the package 600 of FIG. 1 , the area where the adhesive 610 is applied has a structure similar to a flat tray on which the adhesive 610 is applied. Fig. 10B In the package 600 , the area where the adhesive 610 is applied has a structure similar to a pool filled with the adhesive 610 .

[0141] The above-mentioned variations are only a part of the variations of this embodiment, and other variations of this embodiment can be implemented according to the above-mentioned embodiment and its variations. In addition, these variations should be included in the scope of the embodiments of the present invention.

[0142] (Other Possible Shapes of Molding Member) Some possible shapes of the molding member of the flip chip package according to the embodiment of the present invention are described below.

[0143] Figures 11A to 11F FIG. 1 is a schematic top view of a flip chip package according to an embodiment of the present invention, used to describe some possible shapes of molding components therein. Figures 11A to 11F In the figure, the heat sink is omitted for simplicity.

[0144] Fig.11A and 11B Each of the figures shows a structure of a molding member (mold) such that the TIM is formed to have a rectangular portion and four arms protruding from the four corners of the rectangular portion toward the four corners of the package. Fig.11A In the case of , the area where the adhesive is applied has a structure similar to a flat tray on which the adhesive is applied. On the other hand, in Fig. 11B In this case, the area where the adhesive is applied has a structure similar to a pool filled with the adhesive.

[0145] Fig. 11C The structure of the molding member is shown such that the TIM is formed to have a rectangular portion and four arms protruding from four corners of the rectangular portion toward four corners of the package. Fig. 11C The structure and Fig. 11B The structures differ in the configuration of the area where the adhesive is applied. Fig. 11B In the case of , there are four separate adhesive pools as areas for applying adhesive. On the other hand, Fig. 11CThe structure has an enlarged adhesive pool, and the pool is used to surround the area of ​​the TIM.

[0146] Fig.11D An example is Fig. 11C The structure of the modified TIM is such that the region of the TIM has a star shape. Fig.11E An example is Fig. 11C The structure of the modified TIM is rounded. Fig.11F An example is Fig. 11C The structure in is modified so that the area of ​​the TIM has a rectangular shape rotated 45 degrees.

[0147] The exemplary shapes of the molding members described above are only a part of possible shapes of the molding members according to the embodiment, and other shapes of the molding members can be realized according to the above examples. In addition, such possible shapes of the molding members should be included in the scope of the embodiments of the present invention.

[0148] (Multi-chip configuration of flip chip package) The following describes multi-chip configurations of flip chip packages according to embodiments of the present invention. These multi-chip configurations correspond to possible variations of flip chip packages according to embodiments of the present invention, respectively.

[0149] Fig. 12A Possible variations of flip chip packaging according to an embodiment of the invention are shown. Fig. 12B Another possible variation of flip chip packaging according to an embodiment of the present invention is shown. Fig. 12A or Fig. 12B The illustrated flip chip package 700 is an example of a flip chip package according to possible variations of the present embodiment.

[0150] The package 700 includes a substrate 701, semiconductor chips (die) 702a and 702b, bumps 703a and 703b, underfills 704a and 704b, TIMs 705a and 705b, a heat sink 706, a stiffener 707, and a molding member 709. The stiffener 707 is bonded to the substrate 701 by an adhesive 708. The heat sink 706 is bonded to the molding member 709 by an adhesive 710.

[0151] Fig. 12A The difference between the package 700 and the package 200 is mainly that the package 700 has a structure with multiple chips (chips 702a and 702b). Although the number of chips in the package 700 is two, it can be based on the same Fig. 12A In a similar manner to package 700 , the technology according to the embodiment of the present invention is applied to a package having three or more chips.

[0152] Optionally, the molding member 709 may have an additional adhesive pool to apply adhesive 710a between adjacent chips, such as Fig. 12B The addition of adhesive 710a enhances the adhesion between the heat sink 706 and the molding member 709, thereby reducing the risk of TIMs 705a and 705b delaminating from the heat sink 706 during the reflow process.

[0153] The above multi-chip configuration can be applied to Figure 7 , 8A 8B, 9A to 9B and 10A to 10B. In addition, Figures 11A to 11F The possible shapes of the molding members shown in can be applied to a multi-chip configuration. Even in the case of a multi-chip configuration, the package of the present embodiment can achieve improved thermal performance, thereby ensuring sufficient operational reliability.

[0154] The above disclosure only discloses exemplary embodiments and is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that the above embodiments and all or part of other embodiments and modifications that can be derived based on the scope of the claims of the present invention are within the scope of the present invention.

Claims

1. A flip chip package, characterized in that: include: at least one chip, used to connect to the substrate; a molding member formed on the substrate to wrap a side portion of the at least one chip and to expose a top surface of each chip, the upper surface of the molding member having a first region continuous with the top surface of each chip, a second region to which an adhesive is applied, and a wall-like structure placed to surround the top surface of each chip, the first region and the second region being separated by the wall-like structure; a heat sink placed over the top surface of the at least one chip and bonded to the molding member by an adhesive applied to the second region; A thermal interface material filled in a space region formed by the first region, the top surface of each chip, at least a portion of the bottom surface of the heat sink, and the first side of the wall-like structure; The heat sink has a first surface portion, a second surface portion and a third surface portion, wherein the first surface portion, the second surface portion and the third surface portion are located in the same plane, the first surface portion is in contact with the thermal interface material, the second surface portion is in contact with the wall-like structure, and the third surface portion is in contact with the adhesive applied to the second area.

2. The flip chip package according to claim 1, characterized in that: Also includes: A reinforcement member having a square frame-like structure is formed on a substrate to surround the outside of a molding member, and the molding member is formed to fill an inner region of the reinforcement member.

3. The flip chip package according to claim 1, characterized in that: The heat sink has a cover portion placed over the at least one chip and a side portion extending downward from an end of the cover portion, the side portion is placed outside the molding member, and the end of the side portion is bonded to a substrate by an adhesive.

4. The flip chip package according to any one of claims 1 to 3, characterized in that: The second region comprises an adhesive pool for being filled with the adhesive, wherein the second side of the wall-like structure forms at least a part of one side of the adhesive pool.

5. A device comprising a circuit using flip chip packaging, characterized in that, The package includes: at least one chip, used to connect to the substrate; a molding member formed on the substrate to wrap a side portion of the at least one chip and to expose a top surface of each chip, the upper surface of the molding member having a first region continuous with the top surface of each chip, a second region to which an adhesive is applied, and a wall-like structure placed to surround the top surface of each chip, the first region and the second region being separated by the wall-like structure; a heat sink placed over the top surface of the at least one chip and bonded to the molding member by an adhesive applied to the second region; A thermal interface material filled in a space region formed by the first region, the top surface of each chip, at least a portion of the bottom surface of the heat sink, and the first side of the wall-like structure; The heat sink has a first surface portion, a second surface portion and a third surface portion, wherein the first surface portion, the second surface portion and the third surface portion are located in the same plane, the first surface portion is in contact with the thermal interface material, the second surface portion is in contact with the wall-like structure, and the third surface portion is in contact with the adhesive applied to the second area.

6. The device according to claim 5, characterized in that Also includes: A reinforcement member having a square frame-like structure is formed on a substrate to surround the outside of a molding member, and the molding member is formed to fill an inner region of the reinforcement member.

7. The device according to claim 5, characterized in that: The heat sink has a cover portion placed over the at least one chip and a side portion extending downward from an end of the cover portion, the side portion is placed outside the molding member, and the end of the side portion is bonded to a substrate by an adhesive.

8. The device according to any one of claims 5 to 7, characterized in that: The second region comprises an adhesive pool for being filled with the adhesive, wherein the second side of the wall-like structure forms at least a part of one side of the adhesive pool.

9. A method for assembling a flip chip package, the flip chip package comprising at least one chip, a substrate, a molding member, a thermal interface material and a heat sink, characterized in that: The method comprises: connecting the at least one chip to the substrate; filling a mold compound around the at least one chip on the substrate to wrap a side portion of the at least one chip and expose a top surface of each chip, and molding the molding member in a structure in which an upper surface of the molding member has a first region continuous with the top surface of each chip, a second region to which an adhesive is applied, and a wall-like structure disposed to surround the top surface of each chip, and the first region and the second region are separated by the wall-like structure; applying the adhesive to a second region of the molding member; Applying thermal interface material on the first area and the top surface of each chip; connecting the heat sink to the thermal interface material and the molding member via the adhesive; performing a reflow process of the flip chip package; The heat sink has a first surface, a second surface and a third surface, the first surface, the second surface and the third surface are located in the same plane, the first surface portion is in contact with the thermal interface material, the second surface portion is in contact with the wall-like structure, and the third surface portion is in contact with the adhesive applied to the second area.

10. The method according to claim 9, characterized in that: Before filling the mold compound, the method further includes forming a stiffener on the substrate, the stiffener having a square frame-like structure for surrounding an entire area on which the at least one chip is disposed, and the molding member is formed to fill an inner area of ​​the stiffener.

11. The method according to claim 9, characterized in that: The heat sink has a cover portion placed over the at least one chip and a side portion extending downward from an end of the cover portion, the side portion is placed outside the molding member, and in the attached heat sink, the end of the side portion is bonded to the substrate by an adhesive.

Images