Package structure and manufacturing method thereof

Abstract

A package structure is provided. A package structure includes a substrate, a die bonded to the substrate, a cap disposed over the package assembly and the substrate, and an interface structure sandwiched between the package assembly and the cap, the interface structure includes a first thermal interface material disposed at a corner of a top surface of the at least one die and a second thermal interface material disposed on a remainder of the top surface of the at least one die. A Young's modulus of the first thermal interface material is less than a Young's modulus of the second thermal interface material. The embodiment of the invention also relates to a method for manufacturing the packaging structure.

Description

Technical Field

[0001] Embodiments of the present application relate to a packaging structure and a method for manufacturing the same. Background Art

[0002] In some three-dimensional integrated circuits (3DICs), the device die is bonded to a package substrate to form a package. The heat generated by the device chip during operation needs to be dissipated to prevent performance degradation or even physical damage. In addition, the package structure may lack structural strength to avoid warping. In order to dissipate heat and improve structural integrity, a metal cap can be bonded to the package substrate to connect the device die. Summary of the invention

[0003] According to one aspect of an embodiment of the present application, a packaging structure is provided, comprising: a substrate; a packaging assembly bonded to the substrate and comprising at least one tube core; a cover disposed above the packaging assembly and the substrate; and an interface structure sandwiched between the packaging assembly and the cover, the interface structure comprising: a first thermal interface material disposed at a corner of a top surface of at least one tube core, and a second thermal interface material disposed on the remaining portion of the top surface of at least one tube core, wherein the Young's modulus of the first thermal interface material is smaller than the Young's modulus of the second thermal interface material.

[0004] According to another aspect of an embodiment of the present application, a packaging structure is provided, comprising: a substrate; a packaging component bonded to the substrate and comprising at least one tube core; a cover arranged above the packaging component and the substrate and comprising a bottom surface and a lower edge; and an adhesive layer sandwiched between the lower edge and the substrate, wherein the adhesive layer comprises: a first adhesive arranged at a corner of the lower edge of the cover, and a second adhesive arranged on the remaining portion of the lower edge of the cover, wherein the Young's modulus of the first adhesive is smaller than the Young's modulus of the second adhesive.

[0005] According to another aspect of an embodiment of the present application, a method for manufacturing a packaging structure is provided, comprising: joining a packaging component to the front side of a substrate, the packaging component comprising a tube core; dispensing a first thermal interface material and a second thermal interface material above a top surface of the tube core; placing a cover over the packaging component and the substrate so that the first thermal interface material and the second thermal interface material are sandwiched between the top surface of the tube core and the bottom surface of the cover; curing the first thermal interface material and the second thermal interface material; and after curing, forming a solder component over the back side of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Various aspects of the present invention will be 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 reduced for clarity of discussion.

[0007] Figure 1 A flow chart of a method for forming a package structure according to various aspects of the present disclosure is shown.

[0008] Figure 2-Figure 8 The present invention shows various aspects of the present invention. Figure 1 Partial cross-sectional views of a semi-finished structure of the various steps of the method that the structure undergoes.

[0009] Fig. 9 A flow chart of a method for forming a package structure according to various aspects of the present disclosure is shown.

[0010] Figure 10-Figure 15 The present invention shows various aspects of the present invention. Fig. 9 Partial cross-sectional views of a semi-finished structure of the various steps of the method that the structure undergoes.

[0011] Fig.16 A flow chart of a method for forming a package structure according to various aspects of the present disclosure is shown.

[0012] Figure 17-Figure 21 The present invention shows various aspects of the present disclosure. Fig.16 Partial cross-sectional views of a semi-finished structure of the various steps of the method that the structure undergoes. DETAILED DESCRIPTION

[0013] The following disclosure provides many different embodiments or examples for realizing different features of the present invention. Specific embodiments or examples of components and arrangements are described below to simplify the present invention. Of course, these are only 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 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 invention 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.

[0014] Additionally, for ease of description, spacing relation terms such as "below," "beneath," "lower," "above," "upper," etc. may be used herein to describe the relationship of one element or component to another element or component as shown in the figures. The spacing relation terms are intended to encompass different orientations of the device in use or in the process of operation in addition to the orientation shown in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spacing relation descriptors used herein may likewise be interpreted accordingly.

[0015] In addition, when a number or a range of numbers is described using the term "about," "approximately," etc., the term is intended to encompass numbers within a reasonable range understood by those skilled in the art to take into account variations that naturally occur during manufacturing. For example, based on known manufacturing tolerances associated with manufacturing features having the properties associated with such number, a number or range of numbers includes a reasonable range that includes the described number, such as within + / - 10% of the described number. For example, a material layer having a thickness of "about 5 nm" may include a size range of 4.25 nm to 5.75 nm, where the manufacturing tolerance associated with depositing the material layer is known to be + / - 15%.

[0016] Semiconductor packaging technology was once considered a back-end process that facilitated the interface between chips and external circuits. Times have changed. Computing workloads have changed significantly, bringing packaging technology to the forefront of innovation. Modern packaging integrates multiple chips or dies into a single semiconductor device. Depending on the stacking level, modern semiconductor packages can have a 2.5D structure or a 3D structure. In a 2.5D structure, at least two dies are coupled to a redistribution layer (RDL) structure or an interposer that provides chip-to-chip communication. At least two dies in a 2.5D structure are not stacked vertically. In a 3D structure, at least two dies are stacked together and interact with each other through through-silicon vias (TSVs). Depending on the process used, 2.5D structures and 3D structures may have an integrated fan-out (InFO) structure or wafer-on-substrate chips. Structure. To provide additional structural integrity and improve heat dissipation, a metal lid or metal ring can be attached to the package structure via a thermal interface material (TIM) or adhesive. The TIM plays an important role in conducting heat to the metal lid. Both TIMs and adhesives are designed to absorb stress and prevent crack propagation. Depending on their composition, TIMs and adhesives can have different thermal conductivities and stiffnesses. In many cases, TIMs and adhesives with higher thermal conductivity or greater stiffness may not absorb stress well.

[0017] The present disclosure provides a hybrid arrangement of a thermal interface material (TIM) and an adhesive to achieve high thermal conductivity, high coplanarity, and high stress absorption. In some embodiments, a package assembly is bonded to the front side of a package substrate. The package assembly may include a plurality of tube cores and may include an interposer or a redistribution layer. The first TIM and the second TIM are allocated to the package assembly. A cover is placed on the package assembly and the package substrate to bond the first TIM and the second TIM. After the first TIM and the second TIM are cured, a solder component is formed on the back side of the package substrate. In some other embodiments, the first TIM and the second TIM are allocated above the package assembly, and the first adhesive and the second adhesive are arranged above the package substrate. The cover is placed above the tube core and the substrate to bond the first TIM and the second TIM and the first adhesive and the second adhesive. After the first TIM, the second TIM, the first adhesive, and the second adhesive are cured, a solder component is formed on the back side of the package substrate.

[0018] Various aspects of the present disclosure will now be described in more detail with reference to the accompanying drawings. In this regard, Figure 1 , Fig. 9 and Fig.16 FIG. 1 is a diagram showing various aspects of the present disclosure in a work-in-progress (WIP) structure 200 (eg, Figure 2-Figure 8 , Figure 10-Figure 15 and Figure 17-Figure 21 Flowcharts of methods 100, 300, and 400 of forming a package structure on a substrate (shown). Methods 100, 300, and 400 are merely examples and are not intended to limit the present disclosure to the contents explicitly shown in methods 100, 300, or 400. Additional steps may be provided before, during, and after methods 100, 300, or 400, and some of the steps described may be replaced, eliminated, or moved for other embodiments of the method. For simplicity, not all steps are described in detail here. Figure 2-Figure 8 Describing method 100, Figure 2-Figure 8 FIG. 2 is a partial cross-sectional view and a top view of a WIP structure 200 at different manufacturing stages according to various embodiments of the method 100. Figure 10-Figure 15 Describing method 300, Figure 10-Figure 15 FIG. 3 is a partial cross-sectional or top view of the WIP structure 200 at different manufacturing stages according to various embodiments of the method 300. Figure 17-Figure 21 Describing method 400, Figure 17-Figure 21 4 is a partial cross-sectional or top view of the WIP structure 200 at different manufacturing stages according to various embodiments of the method 400. Because the WIP structure 200 will be manufactured into a package structure, the WIP structure 200 may be referred to herein as the package structure 200 as the context requires. For the avoidance of doubt, Figure 2-Figure 8 , Figure 10-Figure 15 and Figure 17-Figure 21The X, Y and Z directions are perpendicular to each other. In the present disclosure, unless otherwise explicitly stated, the same reference numerals denote the same features.

[0019] refer to Figure 1 and Figure 2 , method 100 includes block 102, wherein a package assembly 240 is bonded to a front side surface 202F of a package substrate 202. In some embodiments, the package substrate 202 may include a printed circuit board (PCB) or the like. Although not explicitly shown in the features, the package substrate 202 may include a through substrate via (TSV) or a through-hole connector extending from the front side surface 202F of the package substrate 202 to the back side surface 202B. In addition, in order to electrically couple to the package assembly, the package substrate 202 may include a plurality of contact pads on the front side surface 202F. In order to electrically couple to a solder component (described below) on the back side 202B, the package substrate 202 may also include a plurality of contact pads or under bump metallization (UBM) components above the back side 202B. At least one passive element 204 may be bonded to the package substrate 202. At least one passive component 204 may include a capacitor or a resistor. The package assembly 240 is a multi-die package (or multi-chip package) that may include more than one device die. Device dies may also be referred to as dies or chips. In the depicted embodiment, the package assembly 240 includes a first die 220, a second die, and an interposer 210. Figure 2 In some embodiments shown, the first die 220 and the second die 230 are bonded to the interposer 210 by a plurality of microbumps 212. The space between the interposer 210 and the first die 220 or between the interposer 210 and the second die 230 can be filled with a first bottom filler 214. The first die 220 and the second die 230 are arranged side by side above the interposer 210. In order to provide structural integrity and improve stress absorption, each of the first die 220 and the second die 230 is surrounded by a molding material 216. The molding material 216 may also be referred to as an encapsulation layer 216. The package assembly 240 also includes a plurality of connection components to interface with the package substrate 202. In some embodiments, the plurality of connection components 206 may include controlled collapse chip connection (C4) bumps or other solder bumps. The space between the package assembly 240 and the front side surface 202F of the package substrate 202 may be filled with a second bottom filler 208.

[0020] The interposer 210 may include a semiconductor material or glass. In one embodiment, the interposer 210 includes silicon (Si). In some alternative embodiments, the interposer 210 includes silicon germanium (SiGe) or silicon carbon (SiC). Each of the first die 220 and the second die 230 may be a system on chip (SOC) die, a logic die, an application specific integrated circuit (ASIC) die, or other device die. That is, each of the first die 220 and the second die 230 may include a plurality of transistors, such as planar transistors, fin field effect transistors (FinFETs), gate-all-around (GAA) transistors, nanowire transistors, nanosheet transistors, or other multi-gate transistors. Although the first die 220 and the second die 230 are Figure 2 2 and 3. The first bottom filler 214 may include a polymer or an epoxy resin. The molding material 216 may include a substrate and a filler embedded in the substrate. In some embodiments, the substrate of the molding material 216 may include a polymer, a resin, or an epoxy resin, and the filler may include spherical particles of silicon oxide (silicon dioxide), zinc oxide, or aluminum oxide.

[0021] At block 102, a package component 240 is placed over the package structure 202 such that the connection features 206 are vertically aligned with the contact pads on the front side surface 202F of the package substrate 202. A reflow process is performed such that the connection features 206 electrically couple the interposer 210 of the package component 240 to the package substrate 202. After the reflow process, a liquid precursor of the second underfill 208 is allowed to fill the gap between the interposer 210 and the front side surface 202F of the package substrate 202 by capillary action. Next, the liquid precursor is cured by annealing to a curing temperature to form the second underfill 208. Figure 2 In some of the embodiments shown, portions of the second underfill 208 may extend along sidewalls of the package component 240 .

[0022] Figure 2 The illustrated package substrate 202 and package component 240 may be collectively referred to as a work-in-progress (WIP) structure 200. During the operations of the various blocks of method 100, components may be added to the work-in-progress (WIP) structure 200, and this disclosure will continue to refer to the resulting structure as a work-in-progress structure 200.

[0023] refer to Figure 1 and Figure 3-Figure 5, the method 100 includes block 104, wherein a first thermal interface material (TIM) 242A and a second TIM 242B are dispensed over the package assembly 240. For the purposes of the present disclosure, a TIM refers to a material placed between an electronic device and a heat sink to improve heat dissipation of the electronic device. Since voids and gaps introduce air into the heat conduction path, and air has a low thermal conductivity, one of the functions of the TIM is to fill the gaps between the electronic device and the heat sink to reduce the voids and gaps. In order to perform the gap filling function well, the TIM or TIM precursor should have reasonable fluidity or flexibility. In addition, the TIM should have sufficient thermal conductivity to promote thermal conduction. In addition, it is desirable that the TIM has good stress absorption properties to protect the electronic device and prevent delamination. According to the present disclosure, the TIM can be applied in liquid form or as a pre-cut tape. Regardless of which type of TIM is used, there is a trade-off between thermal conductivity and stress absorption capacity. It has been observed that TIMs with higher thermal conductivity tend to be rigid, which tends to result in lower stress absorption capacity. In contrast, flexible TIMs tend to have satisfactory stress absorption capacity but poor thermal conductivity.

[0024] It has been observed through experiments, simulations, and field data that stress tends to concentrate at the corners of a rectangular die. When the TIM lacks flexibility, stress concentration may cause cracks in the TIM. The cracks may propagate into the molding material 216 and the first bottom filler 214 to cause delamination of the first die 220 or the second die 230. According to the present disclosure, two types of TIMs are allocated or applied at block 104—a first TIM 242A and a second TIM 242B. The first TIM 242A and the second TIM 242B have different properties. The first TIM 242A is used as a primary thermally conductive medium, and its thermal conductivity is greater than the thermal conductivity of the second TIM 242B. The second TIM 242B is used as a primary stress absorber, and its Young's modulus is less than that of the first TIM 242A.

[0025] The first TIM 242A may be applied as a tape or dispensed as a liquid. When the first TIM 242A is a tape, the first TIM 242A may include a metal (i.e., copper or aluminum), graphite, or graphene. When the first TIM 242A is dispensed in liquid form, the first TIM 242A may include a substrate and a thermally conductive filler. In some cases, the substrate for the first TIM 242A may include a resin or epoxy, and the thermally conductive filler for the first TIM 242A may include a metal oxide (e.g., aluminum oxide, zinc oxide), aluminum nitride, hexagonal boron nitride, a metal (i.e., copper, silver, or aluminum), diamond, graphene, or graphite. The second TIM 242B is dispensed in a liquid and may include a flexible substrate and a thermally conductive filler. For the avoidance of doubt, the Young's modulus of the flexible substrate is less than the Young's modulus of the substrate of the first TIM 242A. In some embodiments, the flexible substrate of the second TIM 242B may include silicone. The thermally conductive filler in the second TIM 242B may include a metal oxide (e.g., aluminum oxide, zinc oxide), aluminum nitride, hexagonal boron nitride, a metal (i.e., copper, silver, or aluminum), diamond, graphene, or graphite. When both the first TIM 242A and the second TIM 242B are dispensed in liquid, the filler content (or filler concentration) in the first TIM 242A is greater than the filler content in the second TIM 242B. Because the second TIM 242B is still in the heat conduction path, it is desirable that the second TIM 242B has high thermal conductivity. That is, since a higher filler content may result in a loss of stress absorption capability, the filler content in the second TIM 242B needs to be lower than the filler content in the first TIM 242A to maintain sufficient stress absorption performance. In some cases, the second TIM 242B may have a Young's modulus of less than 1 MPa (megapascals).

[0026] Reference now Figure 3-Figure 5 Each of the first die 220 and the second die 230 includes a rectangular shape in a top view. In some embodiments, each of the first die 220 and the second die 230 has a length and a width between about 30 mm and about 50 mm. Figure 3-Figure 5 In some embodiments shown, the second TIM 242B is distributed at or around four (4) corners of each of the first die 220 and the second die 230. At the interface between the first die 220 and the second die 230, the second TIM 242B may span from one corner of the first die 220 over the molding material 216 and extend to one corner of the second die 230. Figure 4 In some embodiments shown, the first TIM 242A is applied as a pre-cut tape, while the second TIM 242B is dispensed as a liquid (or gel, ointment, grease) using a precision dispensing system. Figure 5In some alternative embodiments shown, the first TIM 242A and the second TIM 242B are dispensed in the form of a liquid (or gel, ointment, or grease) using a pre-dispensing system. Figure 4 and Figure 5 As shown, a droplet of the second TIM 242B is disposed at each of the four (4) corners of the first die 220 and the second die 230, while a strip or droplet of the first TIM 242A is attached to the non-corner areas of the first die 220 and the second die 230. Figure 4 and Figure 5 In the illustrated embodiment, the dispensed droplets of the second TIM 242B are separated from the pre-cut strips or droplets of the first TIM 242A. In some alternative embodiments not explicitly shown, the dispensed droplets of the second TIM 242B are in contact with the pre-cut strips or droplets of the first TIM 242A.

[0027] refer to Figure 1 and Figure 3-Figure 5 , method 100 includes block 106, wherein adhesive 246 is dispensed over package substrate 202. Adhesive 246 is used to attach lid 250 (described below) to package substrate 202. Because heat is generated by package component 240 rather than package substrate 202, adhesive 246 does not play a meaningful role in heat dissipation. Therefore, it is more important for adhesive 246 to have stress absorption properties than to have good thermal conductivity. In some embodiments, adhesive 246 may include a substrate and a structural filler. In some cases, the substrate for adhesive 246 may include silicone, nylon, polyetheretherketone (PEEK), epoxy, or resin, and the structural filler of adhesive 246 may include silicon dioxide, zinc oxide, aluminum oxide, silver, or aluminum. It has been observed that the Young's modulus of adhesive 246 increases with the content of structural filler in adhesive 246. When adhesive 246 has a low structural filler content (or low structural filler concentration) and a low Young's modulus, the elasticity of adhesive 246 allows adhesive 246 to better absorb stress. When adhesive 246 has a high structural filler content and a high Young's modulus, the rigidity of adhesive 246 helps maintain coplanarity of cap 250 or ring 270 (described below). In the depicted embodiment, adhesive 246 is dispensed as a liquid (or gel, ointment, grease) using a precision dispensing system.

[0028] refer to Figure 1 and Figure 6-Figure 7, the method 100 includes block 108, where a cover 250 is placed on the package component 240 and the package substrate 202 to bond the first TIM 242A, the second TIM 242B, and the adhesive 246. In some embodiments, the cover 250 can be formed of a metal or an alloy, such as aluminum (Al), copper (Cu), iron (Fe), nickel (Ni), cobalt (Co), or an alloy thereof. Example alloys may include aluminum-copper alloys, iron-nickel alloys, or iron-nickel-cobalt alloys. Because the cover 250 is formed of a metal or a metal alloy, it may be referred to as a metal cover. The cover 250 has at least three functions. First, it acts as a heat sink to dissipate heat from the package component 240 through the first TIM 242A and the second TIM 242B. Second, it provides structural rigidity to the package substrate 202 to prevent or reduce warping. Third, it creates a sealed environment to protect the package component 240. At block 108 , lid 250 is placed over package assembly 240 and package substrate 202 with its bottom edge engaged with adhesive 246 and its backside surface pressed against and engaged with first TIM 242A and second TIM 242B.

[0029] like Figure 6-Figure 7 As shown, when the first TIM 242A and the second TIM 242B are dispensed in liquid form, the cover 250 compresses the first TIM 242A and the second TIM 242B to spread them out to cover a larger surface of the package component 240. In some embodiments shown, the first TIM 242A and the second TIM 242B merge without any voids or gaps at the interface between the first TIM 242A and the second TIM 242B. When the first TIM 242A is applied as a pre-cut tape, the first TIM 242A acts as a spacer to define the thickness of the first TIM 242A and the second TIM 242B between the package component 240 and the back side of the cover 250. Figure 7 In some embodiments shown, after placement of the cover 250, the second TIM 242B and adhesive 246 spread out as the cover 250 is pressed onto the package assembly 240 and the package substrate 202 at block 108. When the first TIM 242A is dispensed as a liquid (or gel, paste, grease), the first TIM 242 may also spread out due to placement of the cover 250. Figure 7 In some of the embodiments shown, the expanded second TIM 242B may span across and contact the molding material 216 .

[0030] refer to Figure 1 and Figure 6-Figure 7, method 100 includes block 110, where the first TIM 242A, the second TIM 242B, and the adhesive 246 are cured. In some embodiments, the first TIM 242A (when dispensed as a liquid), the second TIM 242B, and the adhesive 246 are heat curable. In these embodiments, Figure 6 The illustrated WIP structure 200 may be annealed to cure the first TIM 242A (when dispensed as a liquid), the second TIM 242B, and the adhesive 246. In some embodiments, the annealing process for curing the first TIM 242A (when dispensed as a liquid), the second TIM 242B, and the adhesive 246 may be between about 130°C and about 180°C. This temperature range is not trivial. When the annealing temperature is below 130°C, the curing process may be prolonged or the curing may be incomplete. When the annealing temperature is above 180°C, the possibility of thermal damage is greater. Please refer to Figure 7 . The edge of each of the first die 220 and the second die 230 may have a first dimension D1. After the first TIM 242A and the second TIM 242B are cured, the cured second TIM 242B may have a second dimension D2 along the edge of the first die 220 or the second die 230. In some embodiments, the first dimension D1 may be between about 30 mm and about 50 mm, and the second dimension D2 may be between about 2 mm and about 4 mm. The ratio of the second dimension D1 to the first dimension D1 may be between about 0.04 and about 0.13, or between about 4% and about 13.3%. Because the second TIM 242B occupies two corners along the edge, the second TIM 242B may engage about 8% to about 26.6% of each edge of the first die 220 and the second die 230. These dimensions or ratios are selected to ensure that there is enough second TIM 242B at the corners to absorb stress, while the low Young's modulus of the TIM 242A does not affect the structural integrity of the package.

[0031] refer to Figure 1 and Figure 8 , the method 100 includes block 112, where a solder component 260 is formed over the backside of the package substrate 202. As described above, the package substrate 202 may also include a plurality of contact pads or under bump metallization (UBM) components on the backside surface 202B. At block 112, the solder component 260 is formed on the plurality of contact pads or UBM components. In some embodiments, the solder component 260 may include an alloy of tin, lead, silver, copper, nickel, bismuth, or a combination thereof.

[0032] In the above method 100, the first TIM 242A and the second TIM 242B are dispensed or applied to the top surface of the package component 240, while the cover 250 is attached to the front side surface 202F of the package substrate 202 using an adhesive 246. Specifically, the second TIM 242B is dispensed at the corner of the die of the package component 240, and the first TIM 242A is applied or dispensed at the non-corner area of ​​the die of the package component 240. The Young's modulus of the second TIM 242B is smaller than that of the first TIM 242A, so that the second TIM 242B has better stress absorption capability. The first TIM 242A is more thermally conductive than the second TIM 242B to better dissipate heat to the cover 250. Fig. 9 The illustrated method 300 differs from the method 100 in that at least two types of adhesives are used to attach the cover 250 to the package substrate 202 .

[0033] refer to Fig. 9 and Figure 2 , the method 300 includes block 302, in which the package component 240 is bonded to the front side surface 202F of the package substrate 202. The operations at block 302 are substantially similar to the operations at block 102 of the above-described method 100. Therefore, for the sake of brevity, the operational details of block 302, the package component 240, and the package substrate 202 are omitted.

[0034] refer to Fig. 9 and Figure 10-12 , the method 300 includes block 304, where the first TIM 242A and the second TIM 242B are distributed to the package component 240. The operation at block 304 is substantially similar to the operation at block 104 of the above-described method 100. Therefore, for the sake of brevity, the details of the operation at block 304, the first TIM 242A, and the second TIM 242B are omitted.

[0035] refer to Fig. 9 and Figure 10-12, method 300 includes block 306, where a first adhesive 246A and a second adhesive 246B are dispensed on package substrate 202. Both first adhesive 246A and second adhesive 246B are used to attach cover 250 (described below) to package substrate 202. Because heat is generated by package assembly 240 rather than package substrate 202, first adhesive 246A and second adhesive 246B do not play a meaningful role in heat dissipation. Therefore, it is more important for first adhesive 246A and second adhesive 246B to have stress absorption properties than to have good thermal conductivity. Both first adhesive 246A and second adhesive 246B may include a substrate and a structural filler. The substrate determines the baseline of the Young's modulus, and the structural filler serves to increase rigidity. It has been observed that stress tends to concentrate at the four (4) corners of cover 250 (described below), which requires an adhesive with a low Young's modulus. It has also been observed that in order to provide coplanarity of cover 250, the adhesive needs to be rigid. At block 306, the first adhesive 246A and the second adhesive 246B are different to provide different stress absorption properties. In one embodiment, the first adhesive 246A and the second adhesive 246B both include the same substrate and the same structural filler. The first adhesive 246A and the second adhesive 246B are different in terms of structural filler content. The substrate may include silicone, nylon, polyetheretherketone (PEEK), epoxy resin or resin, and the structural filler may include silicon dioxide, aluminum oxide, zinc oxide, silver or aluminum. In this embodiment, the first adhesive 246A has a first structural filler content of about 70% to about 90%, and the second adhesive 246B has a second structural filler content of about 30% to about 70%. The first structural filler content falls within the range generally considered to be sufficient to provide sufficient mechanical strength in the industry. The second structural filler content can be considered in the industry as not having enough filler to provide sufficient mechanical strength.

[0036] In another embodiment, the first adhesive 246A and the second adhesive 246B can share the same structural filler, but have different substrates. The first adhesive 246A includes a first substrate, and the second adhesive 246B includes a second substrate. The Young's modulus of the second substrate is less than the Young's modulus of the first substrate. In some cases, the first substrate of the first adhesive 246A includes epoxy resin and resin, and the second substrate of the second adhesive 246B includes silicone. Due to the smaller Young's modulus, the second substrate makes the second adhesive more elastic and has better stress absorption capacity. Due to the larger Young's modulus, the first substrate makes the first adhesive 246A rigid to provide better coplanarity of the cover 250.

[0037] At block 306, the first adhesive 246A and the second adhesive 246B are dispensed as a liquid (or gel, ointment, or grease). Fig.11 and Fig.12As shown, first adhesive 246A is dispensed over the landing areas at the four (4) bottom edges of cover 250 , and second adhesive 246B is dispensed over the landing areas at the four corners of cover 250 .

[0038] refer to Fig. 9 and Figure 13-Figure 14 , method 300 includes block 308, wherein a cover 250 is placed over package component 240 and package substrate 202 to bond first TIM 242A, second TIM 242B, first adhesive 246A, and second adhesive 246B. In some embodiments, cover 250 may be formed of a metal or alloy, such as aluminum (Al), copper (Cu), iron (Fe), nickel (Ni), cobalt (Co), or alloys thereof. Example alloys may include aluminum-copper alloys, iron-nickel alloys, or iron-nickel-cobalt alloys. Because cover 250 is formed of a metal or a metal alloy, it may be referred to as a metal cover. At block 308, cover 250 is placed over package component 240 and package substrate 202 so that its bottom edge is bonded to first adhesive 246A and second adhesive 246B, and its backside surface is pressed against and bonded to first TIM 242A and second TIM 242B.

[0039] like Figure 13-Figure 14 As shown, the cover 250 compresses the first TIM 242A and the second TIM 242B, causing them to expand to cover a larger surface of the package component 240. In the depicted embodiment, the first TIM 242A and the second TIM 242B are merged without any gap or gap at the interface between the first TIM 242A and the second TIM 242B. Fig.14 In some embodiments shown, the spread second TIM 242B can span over and contact the molding material 216. Similarly, the cover 250 presses the first adhesive 246A and the second adhesive 246B onto the packaging substrate 202 to spread them over a larger area of ​​the packaging substrate 202. In some embodiments shown in the figures, the first adhesive 246A and the second adhesive 246B merge without any voids or gaps at the interface between the first adhesive 246A and the second adhesive 246B. Please refer to Fig.14 . The cover 250 has a rectangular shape in a top view. Each edge of the cover 250 can have a first length LA that is engaged with the first adhesive 246A and a second length LB that is engaged with the second adhesive 246B. In some embodiments, the first length LA accounts for about 70% to about 80% of the edge of the cover 250, while the second length LB accounts for about 10% to about 15% of the edge of the cover 250. These ratios and percentages are selected to ensure that there is enough second adhesive 246B at the corners to absorb stress, while the low Young's modulus of the second adhesive 246B does not affect the structural integrity of the package.

[0040] refer to Fig. 9 and Figure 13-Figure 14 , method 300 includes block 310, wherein the first TIM 242A, the second TIM 242B, the first adhesive 246A and the second adhesive 246B are cured. In some embodiments, the first TIM 242A, the second TIM 242B, the first adhesive 246A and the second adhesive 246B are heat curable. In these embodiments, Fig.13 The WIP structure 200 shown may be subjected to an annealing process to cure the first TIM 242A (when dispensed as a liquid), the second TIM 242B, the first adhesive 246A, and the second adhesive 246B. In some embodiments, the annealing process for curing the first TIM 242A (when dispensed as a liquid), the second TIM 242B, the first adhesive 246A, and the second adhesive 246B may be between about 130° C. and about 180° C. Please refer to Fig.14 . Cover 250 has a rectangular shape in a top view. Each edge of cover 250 may have a first length LA that is engaged with first adhesive 246A and a second length LB that is engaged with second adhesive 246B. In some embodiments, first length LA accounts for about 70% to about 80% of the edge of cover 250, and second length LB accounts for about 10% to about 15% of the edge of cover 250.

[0041] refer to Fig. 9 and Fig.15 , the method 300 includes block 312, in which a solder component 260 is formed over the back side of the package substrate 202. The operations at block 312 are substantially similar to the operations at block 112 of the above-described method 100. Therefore, for the sake of brevity, details of the operations at block 312 and the solder component 260 are omitted.

[0042] In the above methods 100 and 300, the first TIM 242A and the second TIM 242B are distributed or applied to the top surface of the package component 240 to join the cover 250. Specifically, the second TIM 242B is distributed at the corner of the die of the package component 240, and the first TIM 242A is applied or distributed at the non-corner area of ​​the die of the package component 240. The Young's modulus of the second TIM 242B is smaller than that of the first TIM 242A, so that the second TIM 242B has better stress absorption capability. The first TIM 242A is more thermally conductive than the second TIM 242B to better dissipate heat to the cover 250. Fig.16The illustrated method 400 differs from the method 100 or the method 300 at least in that the ring 270 is attached to the package substrate 202 using the first adhesive 246A and the second adhesive 246B instead of the cover 250. The method 400 does not dispense or apply any TIM on the package assembly 240 because the top surface of the package assembly is exposed for air cooling or docking with an optional cooling device.

[0043] refer to Fig.16 and Figure 2 , the method 400 includes block 402, in which the package component 240 is bonded to the front side surface 202F of the package substrate 202. The operations at block 402 are substantially similar to the operations at block 102 of the above-described method 100. Therefore, for the sake of brevity, the operational details of block 402, the package component 240, and the package substrate 202 are omitted.

[0044] refer to Fig.16 and Figure 17-Figure 18 , method 400 includes block 404, where first adhesive 246A and second adhesive 246B are dispensed over packaging substrate 202. The operations at block 404 are substantially similar to the operations at block 306 of method 300 described above. Therefore, for the sake of brevity, the details of the operations at block 404 are omitted.

[0045] refer to Fig.16 and Figure 19-20 , method 400 includes block 406, where ring 270 is placed on packaging substrate 202 to engage first adhesive 246A and second adhesive 246B. In some embodiments, ring 270 may be formed of a metal or alloy, such as aluminum (Al), copper (Cu), iron (Fe), nickel (Ni), cobalt (Co), or alloys thereof. Example alloys may include aluminum-copper alloys, iron-nickel alloys, or iron-nickel-cobalt alloys. Because ring 270 is formed of a metal or a metal alloy, it may be referred to as a metal ring. At block 406, ring 270 is placed on packaging substrate 202 so that its bottom edge engages first adhesive 246A and second adhesive 246B. Figure 19-20 As shown, ring 270 presses first adhesive 246A and second adhesive 246B against packaging substrate 202 to spread first adhesive 246A and second adhesive 246B over a larger area of ​​packaging substrate 202 .

[0046] refer to Fig.16 and Figure 19-20 , method 400 includes block 408, wherein first adhesive 246A and second adhesive 246B are cured. In some embodiments, first adhesive 246A and second adhesive 246B are heat curable. In these embodiments, Fig.19The WIP structure 200 shown may be subjected to an annealing process to cure the first adhesive 246A and the second adhesive 246B. In some embodiments, the annealing process for curing the first adhesive 246A and the second adhesive 246B may be between about 130° C. and about 180° C. Fig. 20 . Ring 270 may have a rectangular shape in a top view. Each edge of ring 270 may have a first length LA that is engaged with first adhesive 246A and a second length LB that is engaged with second adhesive 246B. In some embodiments, first length LA accounts for about 70% to about 80% of the edge of ring 270, and second length LB accounts for about 10% to about 15% of the edge of ring 270.

[0047] refer to Fig.16 and Fig.21 , the method 400 includes block 410, in which a solder component 260 is formed over the back side of the package substrate 202. The operations at block 410 are substantially similar to the operations at block 112 of the above-described method 100. Therefore, for the sake of brevity, details of the operations at block 410 and the solder component 260 are omitted.

[0048] The present disclosure provides many embodiments. In one aspect, the present invention provides a packaging structure. The packaging structure includes a substrate, a packaging component bonded to the substrate and including at least one tube core, a cover arranged above the packaging component and the substrate, and an interface structure sandwiched between the packaging component and the cover. The interface structure includes a first thermal interface material arranged at a corner of the top surface of at least one tube core and a second thermal interface material arranged on the rest of the top surface of at least one tube core. The Young's modulus of the first thermal interface material is less than the Young's modulus of the second thermal interface material.

[0049] In some embodiments, the thermal conductivity of the second thermal interface material is greater than the thermal conductivity of the first thermal interface material.

[0050] In some embodiments, the first thermal interface material comprises a first substrate and a filler, the second thermal interface material comprises a second substrate and a filler, and a filler concentration in the second thermal interface material is greater than a filler concentration in the first thermal interface material.

[0051] In some embodiments, the first substrate is different from the second substrate.

[0052] In some embodiments, the first substrate comprises silicone and the second substrate comprises resin or epoxy.

[0053] In some embodiments, the filler includes aluminum oxide, zinc oxide, aluminum nitride, hexagonal boron nitride, copper, silver, aluminum, diamond, graphene, or graphite.

[0054] In some embodiments, the cover includes a lower edge that is rectangular in shape.

[0055] In some embodiments, the packaging structure further includes: an adhesive layer sandwiched between the lower edge of the cover and the substrate, wherein the adhesive layer includes: a first adhesive disposed at a corner of the lower edge of the cover, and a second adhesive disposed on the remainder of the lower edge of the cover.

[0056] In some embodiments, wherein the first adhesive and the second adhesive include an adhesive base material and an adhesive filler, wherein a concentration of the adhesive filler in the second adhesive is greater than a concentration of the adhesive filler in the first adhesive.

[0057] In some embodiments, wherein the adhesive substrate comprises silicone, nylon, polyetheretherketone (PEEK), epoxy, or resin, wherein the adhesive filler comprises silicon dioxide, zinc oxide, aluminum oxide, silver, or aluminum.

[0058] On the other hand, the present invention provides a packaging structure. The packaging structure includes a substrate, a packaging component bonded to the substrate and including at least one tube core, a cover disposed above the packaging component and the substrate and including a bottom surface and a lower edge, and an adhesive layer sandwiched between the lower edge and the substrate. The adhesive layer includes a first adhesive disposed at a corner of the lower edge of the cover and a second adhesive disposed at the remaining portion of the lower edge of the cover. The Young's modulus of the first adhesive is less than the Young's modulus of the second adhesive.

[0059] In some embodiments, the shape of the lower edge is rectangular, including four (4) sides. Each of the four (4) sides has a length. The first adhesive is bonded to about 20% to about 30% of the length of each of the four sides, and the second adhesive is bonded to about 70% to about 80% of the length of each of the four sides. In some embodiments, the first adhesive and the second adhesive include an adhesive substrate and an adhesive filler, and the adhesive filler concentration in the second adhesive is greater than the adhesive filler concentration in the first adhesive. In some embodiments, the adhesive substrate includes silicone, nylon, polyetheretherketone (PEEK), epoxy resin or resin, and the adhesive filler includes silicon dioxide, zinc oxide, aluminum oxide, silver or aluminum. In some embodiments, the cover includes aluminum (Al), copper (Cu), iron (Fe), nickel (Ni), cobalt (Co) or its alloy.

[0060] In another aspect, the present disclosure provides a method. The method includes: bonding a package assembly to a front side of a substrate, the package assembly including a die; dispensing a first thermal interface material and a second thermal interface material over a top surface of the die; placing a lid over the package assembly and the substrate such that the first thermal interface material and the second thermal interface material are sandwiched between the top surface of the die and a bottom surface of the lid; curing the first thermal interface material and the second thermal interface material; and after curing, forming a solder feature over a back side of the substrate.

[0061] In some embodiments, the top surface of the tube core is rectangular in shape. The first thermal interface material is disposed at four (4) corners of the top surface of the tube core, and the second thermal interface material is disposed at the remaining portion of the top surface of the tube core. In some embodiments, the Young's modulus of the first thermal interface material is less than the Young's modulus of the second thermal interface material. In some embodiments, the first thermal interface material includes a first substrate and a filler, and the second thermal interface material includes a second substrate and a filler. The filler concentration in the second thermal interface material is greater than the filler concentration in the first thermal interface material. In some embodiments, the first substrate is different from the second substrate.

[0062] The features of several embodiments are summarized above so that those of ordinary skill in the art can better understand aspects of the present disclosure. Those of ordinary skill in the art should understand that they can easily use the present disclosure as a basis for designing or modifying other processes and structures to achieve the same purposes and / or the same advantages of the embodiments described herein. Those of ordinary skill in the art should also be aware 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.

[0063] The features of several embodiments are summarized above so that those skilled in the art can better understand the various aspects of the present disclosure. Those skilled in the art will appreciate that they can easily use the present disclosure as a basis for designing or modifying other processes and structures for realizing the same purpose of the embodiments introduced herein and / or realizing the same advantages thereof. Those skilled in the art will also appreciate that such equivalent structures do not deviate from the spirit and scope of the present invention, and they can make various changes, substitutions and changes in the present invention without deviating from the spirit and scope of the present invention.

Claims

1. A packaging structure, comprising: substrate; a package assembly bonded to the substrate and comprising at least one die; a cover disposed above the packaging assembly and the substrate; as well as An interface structure, sandwiched between the packaging component and the cover, the interface structure comprising: a first thermal interface material disposed at a corner of a top surface of the at least one die, and a second thermal interface material disposed over a remaining portion of the top surface of the at least one die, Wherein, the Young's modulus of the first thermal interface material is smaller than the Young's modulus of the second thermal interface material.

2. The packaging structure according to claim 1, wherein: The thermal conductivity of the second thermal interface material is greater than the thermal conductivity of the first thermal interface material.

3. The packaging structure according to claim 1, in, The first thermal interface material comprises a first substrate and a filler, Wherein, the second thermal interface material comprises a second substrate and the filler, Wherein, the filler concentration in the second thermal interface material is greater than the filler concentration in the first thermal interface material.

4. The packaging structure according to claim 3, in, The first substrate comprises silicone resin, Wherein, the second substrate comprises resin or epoxy resin.

5. The packaging structure according to claim 3, wherein: The filler includes aluminum oxide, zinc oxide, aluminum nitride, hexagonal boron nitride, copper, silver, aluminum, diamond, graphene or graphite.

6. The packaging structure according to claim 1, wherein: The cover includes a lower edge that is rectangular in shape.

7. The packaging structure according to claim 6, further comprising: an adhesive layer sandwiched between the lower edge of the cover and the substrate, Wherein, the adhesive layer comprises: a first adhesive disposed at a corner of the lower edge of the cover, and A second adhesive is disposed on a remaining portion of the lower edge of the cover.

8. A packaging structure, comprising: substrate; a package assembly bonded to the substrate and comprising at least one die; a cover disposed over the package assembly and the substrate and comprising a bottom surface and a lower edge; as well as an adhesive layer sandwiched between the lower edge and the substrate, Wherein, the adhesive layer comprises: a first adhesive disposed at a corner of the lower edge of the cover, and a second adhesive, disposed on the remainder of the lower edge of the cover, Wherein, the Young's modulus of the first adhesive is smaller than the Young's modulus of the second adhesive.

9. The packaging structure according to claim 8, in, The lower edge is rectangular in shape and comprises four sides, wherein each of the four sides has a length, wherein the first adhesive is bonded to about 20% to about 30% of the length of each of the four sides, The second adhesive is bonded to about 70% to about 80% of the length of each of the four sides.

10. A method for manufacturing a packaging structure, comprising: bonding a package assembly to the front side of the substrate, the package assembly comprising a die; dispensing a first thermal interface material and a second thermal interface material over a top surface of the die; placing a lid over the package assembly and the substrate such that the first thermal interface material and the second thermal interface material are sandwiched between a top surface of the die and a bottom surface of the lid; curing the first thermal interface material and the second thermal interface material; as well as After the solidification, solder features are formed over the back side of the substrate.

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