Integrated circuit package assembly

Abstract

One aspect of the present disclosure relates to an integrated circuit (IC) package assembly. The IC package assembly includes a printed circuit board (PCB); a package IC structure mounted on the top surface of the PCB; a heat sink structure disposed over the package IC structure; and the back plate is fixed on the bottom surface of the PCB. The back plate includes a base portion and a protrusion portion. A protrusion protrudes from the base, and a portion of the PCB is under the package IC structure. A lateral width of the protrusion is less than a lateral width of the base.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to integrated circuit package assemblies. Background Art

[0002] The electronics industry has experienced a growing demand for smaller and faster electronic devices that are simultaneously capable of supporting a greater number of increasingly complex and sophisticated functions. To meet these demands, there has been a trend in the integrated circuit (IC) industry to manufacture low-cost, high-performance, and low-power ICs. To date, these goals have been achieved in large part by reducing IC size (e.g., minimum IC component size), thereby improving production efficiency and reducing associated costs. However, this scaling has also increased the complexity of IC manufacturing processes. Therefore, to achieve continued advancements in IC devices and their performance, similar advancements in IC manufacturing processes and technologies are required.

[0003] The demand for more power and more compact chip space (e.g., in high performance computing (HPC) and artificial intelligence (AI) applications) requires corresponding advances in thermal management. For example, in HPC and AI applications, a key issue is the heat dissipation of hot spots within the CPU and GPU. CPUs and GPUs can have up to 4W / mm surrounded by total chip power greater than about 400W to about 600W. 2 The maximum power density of 3DIC packages is 100%. However, current 3DIC package configurations may not be able to achieve such thermal requirements. The heat dissipation efficiency in existing 3DIC packages needs to be improved to meet the power requirements of data centers running HPC and AI workloads.

[0004] Thus, while existing 3DIC packages are generally adequate for their intended purposes, they are not satisfactory in every respect. Summary of the invention

[0005] Some embodiments of the present disclosure provide an integrated circuit (IC) packaging assembly, which includes: a printed circuit board (PCB); a packaged IC structure mounted on the top surface of the PCB; a heat sink structure disposed above the packaged IC structure; and a backplate fixed on the bottom surface of the PCB, wherein the backplate includes a base and a protrusion, wherein the protrusion protrudes from the base and a portion of the PCB is located under the packaged IC structure, wherein a lateral width of the protrusion is smaller than a lateral width of the base.

[0006] Other embodiments of the present disclosure provide an integrated circuit (IC) packaging assembly, which includes: a packaging substrate; a die located above the packaging substrate; a first thermal interface material (TIM) layer located above the die; a metal cover located above the TIM layer; a second TIM layer located above the metal cover; a heat sink structure located above the second TIM layer; and a backplate located below the packaging substrate, wherein the backplate includes a base, a protrusion, and an elastic pad between the protrusion and the packaging substrate, wherein the protrusion protrudes from the base, and wherein the protrusion is located below the die.

[0007] Another embodiment of the present disclosure provides an integrated circuit (IC) packaging assembly, which includes: a packaging substrate; a die located above the packaging substrate; a surface mount (SMT) component mounted on the back side of the packaging substrate; and a backplate located below the packaging substrate, wherein the backplate includes a base and a protrusion, wherein the protrusion protrudes from the base and presses against the back side of the packaging substrate, wherein the protrusion is located below the die and presses against the back side of the packaging substrate without contacting the SMT component. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, in accordance with standard practice in the industry, the various components are not drawn to scale and are for illustration purposes only. In fact, the dimensions of the various components may be arbitrarily increased or decreased for clarity of discussion. It should also be emphasized that the drawings illustrate only typical embodiments of the present application and, therefore, should not be considered limiting in scope, as the present application may be equally applicable to other embodiments. In addition, the drawings may implicitly describe components that are not explicitly described in the detailed description.

[0009] Figure 1 An integrated circuit (IC) package assembly having a backplate configured to apply physical compression to improve heat distribution according to an embodiment of the present disclosure is shown.

[0010] Figure 2 An IC package assembly (eg, Figure 1 An IC package assembly), wherein a back plate is fixed to a heat sink structure.

[0011] Figure 3 An IC package assembly (eg, Figure 1 Mechanisms for enhanced heat transfer in IC package components.

[0012] Figure 4A and Figure 4B A mechanism for enhanced heat transfer using leaf spring arms as part of an IC package assembly backplate according to an embodiment of the present disclosure is shown.

[0013] Figure 5 An IC package assembly having a backplate with protruding pads according to an embodiment of the present disclosure is shown.

[0014] Figure 6 An IC package assembly having a backplate with protruding segments according to an embodiment of the present disclosure is shown.

[0015] Figure 7 An IC package assembly having protruding segments with irregular bump sizes according to an embodiment of the present disclosure is shown.

[0016] Figure 8 An IC package assembly having a back plate with a spring unit according to an embodiment of the present disclosure is shown.

[0017] Fig.9A , Fig. 9B , Fig. 9C and Fig.9D Back plates with various types of square and rectangular protrusion features are shown according to various embodiments of the present disclosure.

[0018] Fig. 10A , Fig. 10B , Fig. 10C and Fig. 10D Back plates with various types of circular (combined with square and rectangular) protrusion features are shown according to various embodiments of the present disclosure. DETAILED DESCRIPTION

[0019] The following disclosure provides many different embodiments or examples for implementing the different components of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these are merely examples and are not intended to be limiting. For example, in the following description, forming a first component above or on a second component may include an embodiment in which the first component and the second component are directly contacted and formed, and may also include an embodiment in which an additional component may be formed between the first component and the second component so that the first component and the second component may not be in direct contact. In addition, the present disclosure may repeat reference numbers and / or letters in various examples. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or configurations discussed.

[0020] Additionally, for ease of description, spatially relative terms such as "below," "beneath," "under," "lower," "above," "above," and the like may be used herein to describe the relationship of one element or component to another element or component as illustrated in the figures. These spatially relative terms are intended to encompass different orientations of a device or apparatus in use or operation in addition to the orientation depicted in the figures. A device or apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0021] Still further, when "about," "approximately," "substantially," and the like are used to describe a value or range of values, the term is intended to encompass values ​​within a reasonable range including the described value, such as within + / -10% of the described value, or other values ​​understood by those skilled in the art. For example, the term "about 5 nm" may encompass a size range from 4.5 nm to 5.5 nm, where the manufacturing tolerance associated with the deposited material layer is known to those of ordinary skill in the art to be + / -10%. And when the size or size of a component is compared to another component, the phrases "substantially the same," "approximately the same," "similar in size," and the like may be understood to be within + / -10% between the compared components. In addition, the disclosed dimensions of different components may implicitly disclose the size ratios between the different components.

[0022] The present disclosure relates to integrated circuit (IC) packaging assemblies. The IC packaging assembly may include stacked IC chips configured in a 3D IC packaging. The stacked IC chips generate a certain amount of power, which requires sufficient thermal management to maintain operation. The present disclosure describes an IC packaging assembly including a backplane, which is configured to apply physical compression to the die (or IC chip) to improve heat distribution. In the current embodiment, each packaging assembly includes at least a die with functional devices (such as logic and memory transistor devices), and the backplane applies force to the die area. The applied force improves the thermal contact of the thermal interface (TIM) layer above the die, thereby improving heat dissipation. It should be noted that the backplane configuration described herein can implement a partial implementation of 3D manufacturing (3D Fabric) (such as CoWoS / InFO / SoIC) in a stand-alone packaging assembly, and 3D manufacturing has multiple dies stacked in a 2.5D and / or 3D IC configuration.

[0023] Figure 1An integrated circuit (IC) package assembly 100 is shown having a backplate 150 configured to apply physical compression to improve heat distribution. The IC package assembly 100 includes a packaged IC structure 250 (or IC package 250) mounted on a top surface of a printed circuit board (PCB) 610. The IC package assembly 100 includes a heat sink structure 700 disposed above the packaged IC structure 250. The IC package assembly 100 includes a backplate 150 disposed below a bottom surface of the PCB 610.

[0024] Still refer to Figure 1 , the packaged IC structure 250 includes at least one tube core 200, and each active device and passive device (for example, transistor device, resistor, capacitor, carrier substrate, etc.) is formed on the tube core 200. Although only one tube core 200 is shown, it should be noted that the packaged IC structure 250 may include more than one tube core 200. In an embodiment, the packaged IC structure 250 may include a plurality of tube cores 200 arranged adjacent to each other in the lateral direction. In an embodiment, the packaged IC structure 250 may include a plurality of tube cores 200 stacked on each other in the vertical direction. In another embodiment, the packaged IC structure 250 may include tube cores 200 arranged adjacent to each other and tube cores 200 stacked on each other to form various integrated 3DIC stacking structures. Each tube core 200 may include a device layer sandwiched between various IC layers and components (for example, sandwiched between the front side interconnect structure and the back side interconnect structure). The device layer is the location where device-level components (for example, transistor devices) are formed. Transistor devices may be logic devices, memory devices, etc. Each transistor device includes a channel region between source / drain (S / D) regions and a gate stack above the channel region. The device layer may also include other device-level components, such as S / D contacts, S / D vias, gate contacts, and / or gate vias, and each device-level component may electrically connect the S / D region and / or gate stack to a higher or lower material layer (e.g., front and / or backside interconnect structures) of the die 200. The die 200 may include a front-side interconnect structure above the device layer and a back-side interconnect structure below the device layer. The front-side interconnect structure and the back-side interconnect structure may include metal lines and vias embedded in an intermetallic dielectric (IMD) layer, and the metal lines and vias may route signals to the transistor devices in the device layer and route signals from the transistor devices in the device layer. In an embodiment, as part of the die 200 (or separated from the die 200), a bonding layer is disposed above the front-side interconnect structure, and a carrier substrate is disposed above the bonding layer. For example, a bonding layer and a carrier substrate (eg, made of silicon) are formed to provide structural support while forming the backside interconnect structure.

[0025] Still refer to Figure 1, the packaged IC structure 250 also includes a thermal interface material (TIM) layer 504a disposed on the top surface of the tube core 200. In an embodiment where there are multiple stacked tube cores 200, the TIM layer 504a is disposed on the top surface of the topmost tube core 200. The TIM layer 504a can be disposed on the front side interconnect structure of the tube core 200 or the top surface of the carrier substrate of the tube core 200. The TIM layer 504a can serve as a thermal conductor and heat distributor on the front side of the tube core 200 to more evenly conduct heat away from the tube core 200. The TIM layer 504a can also serve as a protective film to prevent moisture from entering from the outside of the packaged IC structure 250. The TIM layer 504a can also serve as an adhesive film to be bonded between the tube core 200 and the lid 506. The TIM layer 504a can include a polymer, a resin or an epoxy resin as a base material, and a filler for improving its thermal conductivity. The filler can include a dielectric filler such as aluminum oxide, magnesium oxide, aluminum nitride, boron nitride and diamond powder. Alternatively, the filler may include a metal filler such as silver, copper, aluminum, or the like.

[0026] Still refer to Figure 1 , the packaged IC structure 250 also includes a lid 506 disposed on the top surface of the TIM layer 504a. The lid 506 can be a metal cap that serves as a cover for the packaged IC structure. In an embodiment, the lid not only covers the top surface of the die, but also covers the TIM layer 504a, the die 200, and the side surface of the C4 layer with the interconnect bump 604 (see description below). In addition to being a cover, the lid 506 also serves as a heat absorber to absorb any heat emitted from the components of the die 200. The lid 506 absorbs heat from the die 200 through the TIM layer 504a. The lid 506 is formed of a metal or a metal alloy having a high thermal conductivity, for example, greater than about 100 W / m / K. For example, the lid can be formed of a metal or a metal alloy selected from Al, Cu, Ni, Co, stainless steel, and alloys thereof. The lid 506 can be mounted to the package substrate 606 via a base bonding joint 605. The base bonding joint 605 can include adhering the lid 506 to the package substrate 606. The base bond joint 605 may be made of any suitable material (eg, epoxy, tape, etc.).

[0027] Still refer to Figure 1, the packaged IC structure 250 also includes a controlled collapse chip connection (C4) layer located below the tube core 200. The C4 layer includes an interconnect bump 604, such as a solder bump or a copper pillar (CuP) bump. The solder bump may include tin, lead, and / or silver, and the CuP bump may include a copper pillar having a solder cap at the end. The solder cap may be made of tin, lead, and / or silver. The interconnect bump 604 is used as a way to connect the chip / die to another chip / die as part of the IC package 250, or to a package substrate 606 as part of the IC package 250. In an embodiment, the C4 layer is disposed on the back side of the backside interconnect structure of the tube core 200. For example, the interconnect bump 604 is disposed on the aluminum bonding pad of the backside interconnect structure. The aluminum bonding pad may be part of the aluminum pad layer. And the aluminum pad layer may be part of the redistribution layer (RDL) structure. The RDL structure may include redistribution wiring embedded in one or more passivation layers. The redistribution wiring may distribute the metal lines of the backside interconnect structure to the aluminum bonding pads of the aluminum bonding pad layer.

[0028] Still refer to Figure 1 , the packaged IC structure 250 also includes a package substrate 606 located below the C4 layer. The package substrate 606 is disposed on the back side of the C4 layer. Or more specifically, the interconnect bumps 604 of the C4 layer land on the landing pads of the package substrate 606. The package substrate 606 generally refers to a semiconductor structure or wafer including a package component (such as other device chips, silicon interposers, dielectric substrates, etc.). The package component is electrically connected to the die 200 through the interconnect bumps 604 of the C4 layer. In an embodiment, the package substrate 606 includes a semiconductor substrate formed of silicon, silicon germanium, silicon carbon, etc.

[0029] Still refer to Figure 1, the packaged IC structure 250 also includes a ball grid array (BGA) structure located below the package substrate 606. The BGA structure may include solder joints 608 that land on the PCB 610. As shown, the solder joints 608 are attached to the back side of the package substrate 606. The BGA structure is configured to join one or more packaged IC structures 250 to a larger circuit board (e.g., PCB 610). For example, the PCB 610 may include a plurality of other packaged IC structures 250 mounted thereon, thereby forming a processor, a controller, a memory unit, or other electronic components. The PCB 610 may also include a surface mount (SMT) component 610a mounted on the back side of the PCB 610. The SMT component 610a may also be referred to as a surface mount device (SMD). The SMT component 610a may include an SMD capacitor, an SMD inductor, a PCB transformer, a diode, a triode, a resistor, an oscillator, or other ICs (e.g., other packaged IC structures 250). It should be noted that the PCB 610 and the package substrate 606 may be collectively referred to as a carrier base, on which the die 200 is mounted. The carrier base may also be generally referred to as a package substrate, a base substrate, a substrate lower layer, etc. The package substrate 606 and the PCB 610 may individually or collectively further include a laminate carrier, a metal lead frame, a ceramic substrate, or other types of substrates.

[0030] Still refer to Figure 1 , the back plate 150 and the heat sink structure 700 vertically clamp the packaged IC structure 250 and the PCB 610. The heat sink structure 700 is disposed above the lid 506 of the packaged IC structure 250. In an embodiment, the IC package assembly 100 also includes a TIM layer 504b disposed on the top surface of the lid 506 and the bottom surface of the heat sink structure 700. The TIM layer 504b provides further heat distribution and bonding functions between the lid 506 and the heat sink structure 700. The TIM layer 504b may include a material similar to the TIM layer 504a. In the illustrated embodiment, the TIM layer 504b may have a greater width in the lateral direction than the TIM layer 504a. For example, the TIM layer 504a extends the width of the tube core 200, the TIM layer 504b extends the width of the lid 506, and the width of the lid is greater than the width of the tube core 200. Since TIM layer 504b is wider than TIM layer 504a, thermal contact issues in TIM layer 504b may be less than thermal contact issues in TIM layer 504a. In addition, TIM layer 504a is closer to die 200 and has a greater impact on heat dissipation than TIM layer 504b.

[0031] Still refer to Figure 1, the back plate 150 is arranged under the PCB 610, and the back plate 150 includes a base 150a and a protrusion 150b. In the illustrated embodiment, the back plate 150 also includes an elastic pad 150c connected to the top surface of the protrusion 150b. The elastic pad 150c can refer to a part separated from the protrusion 150b or a part of the protrusion 150b. In some embodiments, the elastic pad 150c is omitted. The base 150a and the protrusion 150b can include the same material, and the width (and / or length) of the base is greater than the protrusion 150b. For example, the base 150a and the protrusion 150b both include metal or metal alloy. In an embodiment, the metal or metal alloy includes Al, Cu, Ni, Co, stainless steel or a combination thereof. The protrusion 150b is configured to be pressed against the back side of the PCB 610 (for example, pressed against the SMT component 610a of the PCB 610). In the illustrated embodiment, the back plate 150 is configured to be in direct mechanical contact with the back side of the PCB 610 via the elastic pad 150c. The elastic pad 150c serves as a cushion that directly touches the back side of the PCB 610 (the SMT component 610a of the PCB 610). The elastic pad 150c is pushed and squeezed by the protrusion 150b. The elastic pad 150c may include any rubber material composed of long chain molecules or polymers. In the present embodiment, the elastic pad 150c may include natural rubber, styrene-butadiene block copolymer, polyisoprene, polybutadiene, ethylene propylene rubber, ethylene propylene diene rubber, silicone elastomer, fluorine-containing elastomer, polyurethane elastomer, or nitrile rubber.

[0032] The IC package assembly 100 further includes a fastener 702 configured to secure the heat sink structure 700 to the back plate 150, or specifically to the base 150a of the back plate 150. The fastener 702 may be a screw, a bolt, or other type of securing member. Figure 1The IC package assembly 100 is shown before the fastener 702 is fixed to the back plate 150. During device operation, if the fastener 702 is not fixed to the back plate 150 (i.e., the protrusion 150b is not pressed on the PCB 610), undesirable warping may occur. For example, without compression, the die 200 will generate heat, and the heat may cause the die 200 to warp downward (as shown), the cover 506 to warp upward (as shown), and the package substrate 606 and PCB 610 to warp downward (as shown). Due to this warping, the TIM layer 504a between the die 200 and the cover 506 may delaminate, resulting in gaps and defects. This delamination increases thermal resistance due to the deterioration of thermal contact between the die 200 and the cover 506. Although this warping may also affect the TIM layer 504b, as described above, the TIM layer 504a is closer to the die 200 and has a greater impact on heat dissipation than the TIM layer 504b. Additionally, TIM layer 504 b is larger than TIM layer 504 a and has a larger thermal surface contact area.

[0033] Figure 2 The IC package assembly 100 is shown with a backplate 150 . Figure 2 and Figure 1 Similar components are similar, and similar components will not be described again for the sake of brevity. Figure 1 The difference is that the back plate 150 is now fixed to the heat sink structure 700. In other words, the fastener 702 is fixed to the back plate 150 so that the protrusion 150b is pressed on the back side of the PCB 610. As shown in the figure, the protrusion 150b (or the elastic pad 150c, if present) can be pressed on the SMT component 610a of the PCB 610. Due to the pressing, the warping of the tube core 200 and the cover 506 is avoided. The pressing of the PCB 610 transfers the force to the projected area of ​​the tube core 200, and the force squeezes the tube core 200 onto the cover 506 so that the TIM layer 504a is substantially free of air gaps and delamination, thereby improving thermal contact. As shown in the figure, the fastener 702 can penetrate the heat sink structure 700 and the PCB 610. The fastener 702 is fastened to the base 150a of the back plate 150.

[0034] Figure 3 An IC package assembly 100 (eg, Figure 1 to Figure 2 The mechanism for enhancing heat transfer in the IC package assembly 100 described in Figure 3, the fastener 702 is to be fixed, and the fastener 702 is fastened to the base 150a of the back plate 150. In this way, mechanical pressure is applied to the packaged IC structure 250, and the heat sink structure 700 is pressed downward onto the packaged IC structure 250. This mechanical pressure is represented by a downward arrow, which indicates the position where the fastener 702 is to be fastened. In order to promote sufficient squeezing to improve thermal performance, the applied mechanical pressure is equal to a force of about 10PSI to 50PSI or about 30kg to 100kg. If the pressure is too small, the force is insufficient to prevent warping. If the pressure is too large, the tube core 200 may be damaged. As described herein, the protrusion 150b is configured to generate a pre-pressure on the back side of the PCB 610. Due to the applied mechanical pressure, the pre-pressure is transmitted to the projection area of ​​the tube core 200. In order to ensure that the force is applied to the projection area of ​​the tube core 200, the protrusion 150b is pressed against the portion of the PCB 610 located directly below the packaged IC structure 250. In other words, the protrusion 150b (or at least a portion thereof) is located directly below the tube core 200. In an embodiment, the protrusion 150b vertically overlaps the entire width of the tube core 200 (as shown in the figure). Due to the compressive force applied to the tube core 200, the thermal contact is improved to promote efficient heat transfer from the packaged IC structure 250 to the system heat sink structure 700 (see the upward arrow). The heat sink structure 700 can include a cooling fan or a cooling plate. The heat sink structure 700 is in thermal contact with the lid 506 (either by directly contacting the lid 506 or indirectly contacting the lid 506 via the TIM layer 504b). In this way, the heat sink structure 700 removes heat from the packaged IC structure 250.

[0035] As power density requirements increase, hot spot heat dissipation becomes one of the most critical issues. The hot spot is the hottest location on the die, typically located in the CPU / GPU area. As described herein, when the chip (e.g., the hot spot of the die 200) heats up, the lid 506 / die 200 / package substrate 606 may warp, resulting in delamination of the TIM layer 504a between the lid 506 and the die 200, which in turn results in poor contact between the lid 506 and the TIM layer 504a interface, resulting in increased air gaps and thermal resistance. The squeezing mechanism described herein eliminates defects caused by poor contact between the lid 506 and the TIM layer 504a (e.g., preventing delamination problems caused by the die 200 bending downward and the lid 506 bending upward). Squeezing also reduces warping of the overall PCB and package to improve mechanical robustness. As described herein, by having the back plate 150 with elastic protrusions (e.g., curvature leaf spring arms, protrusion segments, and / or spring units), a pre-stress is generated on the back side of the PCB 610 within the projection area (e.g., targeting hot spots) of the die 200. This reduces the TIM delamination problem. In an embodiment, the elastic protrusions may include, but are not limited to, metal materials such as aluminum (Al) and stainless steel (SUS).

[0036] Reference now Figure 3 As shown in the right figure of FIG. 1 , the protrusion 150b may include a curved leaf spring arm. The curved leaf spring arm may be a flat spring with a middle curved portion that presses against the PCB 610, as indicated by the upward arrow. The end (flat portion) of the flat spring may be mounted to the base 150a. FIG. 4A to FIG. 4B A mechanism for enhancing heat transfer using leaf spring arms as part of the backplate 150 of the IC package assembly 100 is shown. Figure 4A The leaf spring arm is shown before compression. Figure 4B The leaf spring arm after compression is shown. For example, when the fastener 702 is tightened and the fastener 702 is fixed to the back plate 150, the mechanical pressure applied by the fastener 702 is absorbed by the leaf spring arm, causing the leaf spring arm to press down and apply a compressive force to the PCB 610. Or more specifically, the curved portion of the leaf spring arm is pressed down, and the curved portion is aligned with the projected area of ​​the tube core 200, thereby transferring the applied force to the projected tube core area. From a top view, the curved leaf spring arm can be plate-shaped or disc-shaped. The pre-compression of the leaf spring can be directed to the hot spot area of ​​the tube core 200.

[0037] Figure 5An IC package assembly 100 is shown with a back plate 150 having a single protruding pad. In other words, the protrusion 150b is a single protruding pad with a uniform lateral width (and / or length). In the case where the lateral width and lateral length are the same, the protrusion 150b is a square protruding pad. Figure 5 Similar to the previous figure described above. As shown, the back plate 150 includes a base 150a and a single protruding pad (i.e., protrusion 150b) protruding from the base 150a, and the base 150a can be a rigid substrate. The base 150a spans a lateral width (and / or length) D1. In an embodiment, the lateral width (and / or length) D1 is in the range of about 50mm to about 200mm. The single protruding pad spans a lateral width (and / or length) D2. In an embodiment, the lateral width (and / or length) D2 is in the range of about 40mm to about 150mm. In this way, the lateral width (and / or length) D1 of the base 150a is greater than the lateral width (and / or length) D2 of the protruding pad (i.e., protrusion 150b). In other words, the lateral width of the protrusion 150b is less than the lateral width of the base 150a. In an embodiment, the ratio between D2 and D1 is in the range of about 0.5 to about 0.14. In an embodiment, the height D3 of the base 150a is in the range of about 0.5 mm to about 5 mm, and the height D4 of the protrusion 150b is in the range of about 0.5 mm to about 5 mm. In an embodiment, the ratio between D3 and D4 is in the range of about 0.5 to about 1.

[0038] Still refer to Figure 5 , it should be noted that the single protruding pad 150b has a pad surface area, the packaged IC structure 250 has a package surface area, and the ratio between the pad surface area and the package surface area is in a range between about 0.8 and about 1.2. In other words, the lateral width (and / or length) of the protrusion 150b and the packaged IC structure 250 can be similar to ensure proper vertical alignment between the protrusion 150b and the packaged IC structure 250. The lateral width (and / or length) of the packaged IC structure 250 can be the lateral width (and / or length) of the packaged IC structure 250 or the lid 506. As shown, the single protruding pad is vertically aligned with the packaged IC structure 250 and is located directly below the packaged IC structure 250. In an embodiment, the single protruding pad vertically overlaps the entire width of the tube core 200, and the entire width of the tube core 200 is less than the width of the packaged IC structure 250. As previously described, the vertical alignment between the protrusion 150b and the packaged IC structure 250 and the tube core 200 is to facilitate targeted compression of the tube core area to improve thermal contact. Even so, with the backplane configuration described herein, PCB 610 may warp by approximately 150 um to approximately 500 um.

[0039] Still refer to Figure 5 , the back plate 150 may include an elastic pad 150c, which is provided as part of the protrusion 150b or separately above the top surface of the protrusion 150b. The elastic pad 150c may have a lateral dimension D2, but the present disclosure is not limited thereto. In any case, the elastic pad 150c (if present) directly contacts the PCB 610 and is pressed against the PCB 610. In the present embodiment, the elastic pad 150c directly contacts the SMT component 610a and is pressed against the SMT component 610a. In order to avoid damaging the SMT component 610a, the elastic pad 150c provides a buffer to limit the upward compression force and alleviate the board stretching effect. In some embodiments, the elastic pad 150c is omitted. For example, if there is no SMT component 610a on the back side of the PCB 610 or if it is not important to avoid squeezing the SMT component 610a, the elastic pad 150c is omitted.

[0040] Figure 6 The IC package assembly 100 is shown with a back plate 150 having a protruding segment. In other words, the protruding portion 150b includes a plurality of protruding segments. In this embodiment, the back plate 150 still includes a base 150a, which can be a rigid substrate. As described above with respect to Figure 5 As described above, the base 150a spans a lateral width (and / or length) D1. The back plate 150 also includes a plurality of protruding segments protruding from the base 150a. The protruding segments are spaced apart from each other, and each protruding segment spans a lateral width (and / or length) D6. The distance between the edge protruding segments can be equal to the lateral width (and / or length) D2, as described above with respect to Figure 5 In an embodiment, the lateral width (and / or length) D6 is in a range between about 1 mm and about 10 mm. In an embodiment, the ratio between D6 and D1 is in a range between about 0.1 and about 0.5. In an embodiment, the base 150a spans a height D3, which is in a range between about 0.5 mm and about 5 mm, and the protrusion 150b spans a height D4, which is in a range between about 0.5 mm and about 5 mm. In an embodiment, the ratio between D3 and D4 is in a range between about 0.5 and about 1.

[0041] Still refer to Figure 6, it should be noted that each protruding segment can include a respective resilient pad 150c, which is disposed above the respective top surface of the protruding segment as part of the protruding segment or separately. As shown, when the SMT component 610a is easily damaged (even when the resilient pad 150c is present), the protruding segment and the resilient pad 150c can be staggered with the SMT component 610a. In this case, the protruding segment avoids touching the SMT component 610a and is directly pressed against the back surface of the PCB 610. The lateral dimension of the resilient pad 150c can be greater than, less than, or equal to the lateral dimension of the protruding segment (e.g., D6).

[0042] Figure 7 An IC package assembly 100 is shown having protrusion segments with irregular bump dimensions. In other words, protrusion 150b is a single segment with irregular lateral width and length. Figure 7 Shows Figure 5 and Figure 6 Combination elements of the illustrated embodiment. Figure 5 Same, Figure 7 The protruding segment in is a single continuous piece protruding from the base 150a and is Figure 6 Likewise, the protruding segment avoids touching the SMT component 610a. Therefore, the protruding segment can be a block with an irregular bump size as long as it fills an area without SMT components 610a (e.g., landing on the PCB 610 and located between the SMT components 610a).

[0043] Figure 8 The IC package assembly 100 is shown with a back plate 150 having spring units. In other words, the protrusion 150b includes a plurality of spring units (e.g., coil springs). In this embodiment, the back plate 150 still includes a base 150a, which can be a rigid substrate. However, the base 150a can include a plate wall to form a groove, and the plurality of spring units are disposed in the groove. As described above with respect to Figure 5 As described, the base 150a spans a transverse width (and / or length) D1. The back plate 150 also includes a plurality of spring units protruding from the base 150a. The spring units may include compression springs, conical springs, torsion springs, helical springs, disc springs, or other types of mechanical springs. The spring units are spaced apart from each other, and each spring unit spans a transverse width (and / or length) D8. The distance between the edge spring units may be equal to the transverse width (and / or length) D2, as described above with respect to Figure 5In an embodiment, the lateral width (and / or length) D8 is in the range of about 3 mm to about 10 mm. In an embodiment, the ratio between D8 and D1 is in the range of about 0.01 to about 0.3. In an embodiment, the height D3 spanned by the groove portion of the base 150a is in the range of about 0.5 mm to about 5 mm, and the height D9 spanned by the plate wall of the base 150a is in the range of about 0.2 mm to about 5 mm. In an embodiment, before the fastener 702 is fixed, the spring unit spans a height D5 beyond the top surface of the plate wall. The height D5 can be in the range of about 5 mm to about 20 mm. After the fastener 702 is fixed, the spring unit spans a height D9 (for example, a height reduced due to the compression of the spring unit). Therefore, the back pressure can be precisely controlled. The height H1 (before compression) from the bottom surface of the base 150a to the top surface of the spring unit can be in the range of about 10 mm to about 30 mm. The ratio of D5 to H1 can be in the range of about 0.3 to about 0.6. In some embodiments, the spring unit can have different elastic moduli. For example, spring units closer to the center of the die 200 may have a larger spring constant.

[0044] 9A to 9D Various types of back plates 150 are shown with square and rectangular protruding features. 9A to 9D In each of the , various square and rectangular protruding components are represented by protrusions 150b, which protrude from the base 150a. 9A to 9D In each of the above, the base 150a has a width and a length in the x and y directions that are greater than the protrusion 150b. 9A to 9D In each of the base 150a, fasteners 702 are fastened to the base 150a. For example, fasteners 702 are fastened to the four corners of the back plate 150. 9A to 9D In each of the above, the protrusion 150b (or at least a portion thereof) overlaps the die 200 (see the dashed box) in the z-direction. In this way, the protrusion 150b applies compression to the target die area.

[0045] Reference now Fig.9A , protrusion 150b can be a single protrusion pad that is substantially mirrored with the x and y dimensions of tube core 200. The single protrusion pad is disposed directly below the area of ​​tube core 200. As shown, the single protrusion pad can be a square with consistent dimensions in the x and y directions. In embodiments where tube core 200 is rectangular, the single protrusion pad can be rectangular to mirror the tube core 200. The single protrusion pad can correspond to about Figure 5 Describe the protruding pads.

[0046] Reference now Fig. 9B, the protrusion 150b may include a plurality of evenly distributed protrusion segments that are disposed directly below the region of the die 200. As shown, the protrusion segments may have uniform dimensions in the x-direction and the y-direction (e.g., Figure 6 Each protruding segment may be spaced apart from each other in the x-direction and the y-direction. In an embodiment, the protruding segment may correspond to Figure 6 For example, the SMT component 610a is staggered with the protruding segments so that the SMT component 610a is not directly pressed against.

[0047] Reference now Fig. 9C , the protrusion 150b can include multiple protrusion segments oriented in different configurations. For example, some of the protrusion segments are rectangular segments extending longitudinally along the perimeter of the tube core 200. The extended rectangular segments can provide structural and uniform stress distribution, while other segments are targeted to specific areas (e.g., segments in the intermediate target or surrounding hot spot areas).

[0048] Reference now Fig.9D , the protrusion 150b may include multiple protrusion segments oriented in yet another different configuration. For example, the protrusion segments have different rectangular sizes and shapes, and they are unevenly distributed under the tube core 200. Some protrusion segments can be connected together to form a protrusion of irregular bump size (such as Figure 7 Some of the protruding segments may be distinct protruding segments spaced apart from other protruding segments.

[0049] Will FIG. 9B to FIG. 9D The protrusion 150b in FIG. 1 is described as corresponding to the protruding segment. In an embodiment, some protrusions 150b may correspond to spring units (such as Figure 8 The present disclosure contemplates that FIG. 9B to FIG. 9D The protrusion 150b in may include all protrusion segments, all spring units, or a combination of protrusion segments and spring units.

[0050] FIG. 10A to FIG. 10D Various types of back plates 150 are shown, with round, square, and rectangular protruding features. FIG. 10A to FIG. 10D In each of the , various round, square and rectangular protruding parts are represented by protrusions 150b, which protrude from the base 150a. FIG. 10A to FIG. 10D In each of the above, the base 150a has a width and a length in the x-direction and the y-direction that are greater than the protrusion 150b. FIG. 10A to FIG. 10D In each of the base 150a, fasteners 702 are fastened to the base 150a. For example, fasteners 702 are fastened to the four corners of the back plate 150. FIG. 10A to FIG. 10DIn each of the above, the protrusion 150b (or at least a portion thereof) overlaps the die 200 (see the dashed box) in the z-direction. In this way, the protrusion 150b applies compression to the target die area.

[0051] Reference now Fig. 10A , the protrusion 150b can include a large circular protrusion pad that is substantially mirrored with the x and y dimensions of the tube core 200. In an embodiment, the protrusion 150b also includes smaller circular protrusion segments that are vertically aligned with the corner areas of the tube core 200. In the event that the stress applied to the middle area is too large, the smaller circular protrusion segments can provide structural and uniform stress distribution for the tube core 200. As shown in the figure, each large circular protrusion pad and corner circular protrusion segment is disposed directly below the area of ​​the tube core 200.

[0052] Reference now Fig. 10B , the protrusion 150b may include a plurality of protrusion segments, which are evenly distributed and disposed directly below the area of ​​the tube core 200. As shown in the figure, the protrusion segments may be square and / or circular with uniform sizes in the x-direction and the y-direction. Each protrusion segment may be spaced apart from each other in the x-direction and the y-direction. In an embodiment, the protrusion segments may correspond to Figure 6 For example, the SMT component 610a is staggered with the protruding segments so that the SMT component 610a is not directly pressed against.

[0053] Reference now Fig. 10C , the protrusion 150b can include multiple protrusion segments oriented in different configurations. For example, some of the protrusion segments are rectangular segments extending longitudinally along the perimeter of the tube core 200. The extended rectangular segments can provide structural and uniform stress distribution, while other segments are targeted to specific areas (e.g., segments in the middle target or surrounding hot spot areas). In the embodiment shown, the middle segment can be a circular segment surrounding a specific area, where the surrounding area includes the SMT component 610a.

[0054] Reference now Fig. 10D , the protrusion 150b may include multiple protrusion segments oriented in yet another different configuration. For example, the protrusion segments have different rectangular and circular sizes and shapes, and they are unevenly distributed under the tube core 200. Some protrusion segments can be connected together to form protrusions of irregular bump sizes (such as Figure 7 Some of the protruding segments may be distinct protruding segments spaced apart from other protruding segments.

[0055] FIG. 10A to FIG. 10D The protrusion 150b in FIG. 1 is described as corresponding to the protruding segment. In an embodiment, some protrusions 150b may correspond to spring units (such as Figure 8 The present disclosure contemplates that FIG. 10A to FIG. 10D The protrusion 150b in may include all protruding segments, all spring units, or a combination of protruding segments and spring units.

[0056] Although not limiting, the present disclosure provides advantages for IC package assemblies. One exemplary advantage is incorporating a backplate with protruding features to improve thermal contact. The protruding features provide compression of the projected area of ​​the die to avoid delamination between the die and the TIM layer. Another exemplary advantage is that the protruding features target hot spots in the IC package. Another exemplary advantage is avoiding compression against SMT components when applying compression to the back side of the PCB. Another exemplary advantage is incorporating an elastomeric pad to cushion the pressure effects of the protruding features on the back side of the PCB. Another exemplary advantage is having various types of protruding features (pads, segments, springs, etc.) depending on the design requirements.

[0057] One aspect of the present disclosure relates to an integrated circuit (IC) package assembly. The IC package assembly includes a printed circuit board (PCB); a packaged IC structure mounted on a top surface of the PCB; a heat sink structure disposed above the packaged IC structure; and a backplane fixed to a bottom surface of the PCB. The backplane includes a base and a protrusion. The protrusion protrudes from the base, and a portion of the PCB is located below the packaged IC structure. The lateral width of the protrusion is less than the lateral width of the base.

[0058] In an embodiment, a packaged IC structure includes: a die; a thermal interface material (TIM) layer disposed on a top surface of the die; and a metal cover disposed on a top surface of the TIM layer. The protrusion is configured to generate a pre-pressure on a back side of the PCB, and the pre-pressure is transferred to a projection area of ​​the die.

[0059] In a further embodiment, the pre-pressure presses the die to the metal cap such that the TIM layer is substantially free of air gaps and delamination.

[0060] In an embodiment, the IC package assembly further comprises: a fastener that fixes the heat sink structure to the back plate, wherein the fastener applies mechanical pressure to the packaged IC structure by fastening on the top surface of the back plate. In a further embodiment, the applied mechanical pressure is approximately equal to 10 PSI to 50 PSI.

[0061] In an embodiment, the IC package assembly further includes: an elastic pad engaged between the protrusion of the back plate and the bottom surface of the PCB.

[0062] In an embodiment, the protrusion of the back plate is a leaf spring arm, a plurality of segments or a plurality of springs.

[0063] In an embodiment, the heat sink structure includes a cooling fan, a cooling plate, or a combination thereof.

[0064] In an embodiment, the PCB includes a surface mount (SMT) component on a back side of the PCB, and the protrusion of the back plate presses against the SMT component.

[0065] In an embodiment, the PCB includes a surface mount (SMT) component on a back side of the PCB, and the protrusion of the back plate avoids pressing against the SMT component.

[0066] Another aspect of the present disclosure relates to an integrated circuit (IC) package assembly. The IC package assembly includes a package substrate; a die located above the package substrate; a first thermal interface material (TIM) layer located above the die; a metal cover located above the first TIM layer; a second TIM layer located above the metal cover; a heat sink structure located above the second TIM layer; and a backplate located below the package substrate. The backplate includes a base, a protrusion, and an elastic pad between the protrusion and the package substrate. The protrusion protrudes from the base. The protrusion is located below the die.

[0067] In an embodiment, the IC package assembly further comprises: a fastener fixing the heat sink structure to the back plate. The fastener is configured to apply a force to a top surface of the metal cover.

[0068] In an embodiment, the base spans a first width, the protrusion spans a second width, and a ratio of the second width to the first width is in a range between about 0.8 and about 1.2.

[0069] In an embodiment, the protrusion vertically overlaps the entire width of the die.

[0070] In an embodiment, the protrusion includes a plurality of protrusion parts, and each of the protrusion parts are spaced apart from each other.

[0071] Another aspect of the present disclosure relates to an integrated circuit (IC) package assembly. The IC package assembly includes a package substrate; a die located above the package substrate; a surface mount (SMT) component mounted on the back side of the package substrate; and a back plate located below the package substrate. The back plate includes a base and a protrusion. The protrusion protrudes from the base and presses against the back side of the package substrate. The protrusion is located below the die and presses against the back side of the package substrate without contacting the SMT component.

[0072] In an embodiment, the protrusion lands between SMT components.

[0073] In an embodiment, the protrusion comprises a plurality of segments or a plurality of springs.

[0074] In an embodiment, the IC package assembly further includes an elastic pad disposed on a top surface of the protrusion, and the elastic pad directly contacts a back side of the package substrate.

[0075] In an embodiment, the IC package assembly further includes a thermal interface material (TIM) layer over the die; a metal cover over the TIM layer; a heat sink structure over the metal cover; and a fastener securing the heat sink structure to the backplate, wherein the fastener applies force to a top surface of the metal cover.

[0076] The details of the method and device of the present disclosure are described in the accompanying drawings. The features of several embodiments are summarized above so that those skilled in the art can better understand the aspects of the present disclosure. Those skilled in the art should understand that they can easily use the present disclosure as a basis to design or modify other processes and structures for implementing the same purpose and / or achieving the same advantages as the embodiments introduced herein. Those skilled in the art should also appreciate that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions and modifications herein without departing from the spirit and scope of the present disclosure.

Claims

1. An integrated circuit package assembly, comprising: Printed circuit boards; a packaged integrated circuit structure mounted on a top surface of the printed circuit board; a heat sink structure, disposed above the packaged integrated circuit structure; as well as a back plate fixed to the bottom surface of the printed circuit board, wherein the back plate includes a base and a protrusion, wherein the protrusion protrudes from the base, and a portion of the printed circuit board is located below the packaged integrated circuit structure, Wherein, the transverse width of the protrusion is smaller than the transverse width of the base.

2. The integrated circuit package assembly according to claim 1, wherein: The packaged integrated circuit structure comprises: Die; a layer of thermal interface material disposed on a top surface of the die; and A metal cover is disposed on the top surface of the thermal interface material layer, wherein the protrusion is configured to generate a pre-pressure on the back side of the printed circuit board, and the pre-pressure is transferred to the projection area of ​​the die.

3. The integrated circuit package assembly according to claim 2, wherein: The pre-pressure presses the die to the metal lid such that the thermal interface material layer is substantially free of air gaps and delamination.

4. The integrated circuit package assembly according to claim 1, further comprising: A fastener secures the heat sink structure to the backplate, wherein the fastener applies mechanical pressure to the packaged integrated circuit structure by fastening to a top surface of the backplate.

5. The integrated circuit package assembly according to claim 4, wherein: The mechanical pressure applied is approximately equal to 10 PSI to 50 PSI.

6. The integrated circuit package assembly of claim 1, further comprising: A resilient pad is engaged between the protrusion of the back plate and the bottom surface of the printed circuit board.

7. The integrated circuit package assembly according to claim 1, wherein: The protrusion of the back plate is a leaf spring arm, a plurality of segments or a plurality of springs.

8. The integrated circuit package assembly according to claim 1, wherein: The heat sink structure includes a cooling fan, a cooling plate or a combination thereof.

9. An integrated circuit package assembly, comprising: Package substrate; A tube die is located above the packaging substrate; a first thermal interface material layer, located above the die; a metal cover, located above the first thermal interface material layer; a second thermal interface material layer, located above the metal cover; A heat sink structure, located above the second thermal interface material layer; as well as A back plate is located below the packaging substrate, wherein the back plate comprises a base, a protrusion and an elastic pad between the protrusion and the packaging substrate, wherein the protrusion protrudes from the base, and wherein the protrusion is located below the tube core.

10. An integrated circuit package assembly, comprising: Package substrate; A tube die is located above the packaging substrate; a surface mount component mounted on the back side of the package substrate; as well as A back plate is located below the packaging substrate, wherein the back plate includes a base and a protrusion, wherein the protrusion protrudes from the base and presses against the back side of the packaging substrate, wherein the protrusion is located below the tube core and presses against the back side of the packaging substrate without contacting the surface mount component.

Images