Reworkable polysiloxanes for thermal interface materials

Abstract

A thermal interface material (TIM) is disclosed that includes a hydroxyl terminated polysiloxane blended with a catalyst generator. When the catalyst generator is activated by a thermal stimulus, cleavage of silicon-oxygen bonds in the hydroxyl-terminated polysiloxane is catalyzed. A semiconductor package and a computing device including the TIM are also disclosed. In addition, a method of providing the TIM and a semiconductor package including the TIM is disclosed. Providing the TIM includes blending a hydroxyl-terminated polysiloxane with a catalyst generator that cleaves a silicon-oxygen bond when activated by a thermal stimulus.

Description

Background Technology

[0001] This disclosure relates to thermal interface materials (TIMs), and more specifically, to polymer composite TIMs.

[0002] TIM (Temperature Insulation) is widely used in electronic packaging to enhance thermal conduction across the interface between a heat source (e.g., a chip) and a heat sink (e.g., fins or a cold plate). The roughness of the interface surface creates non-contact areas, which, if occupied by air, result in high contact thermal resistance (R0) between the surfaces. c Therefore, using a thermally conductive membrane (TIM) with a much higher thermal conductivity (k) than air to fill the gaps can significantly reduce the contact thermal resistance at these interfaces. Examples of TIMs can include metals (e.g., liquids, solders, or foils), polymer composites, carbon-based materials, and phase change materials (PCMs). Polymer composite TIMs consist of a polymer matrix (body) filled with a thermally conductive material (filler). Flexible matrix polymers can achieve higher thermal conductivity than filler materials alone by improving the contact between interfacial surfaces.

[0003] However, TIM needs to meet the requirements of semiconductor devices in high k and low R c The increasing demands for high conformability remain a challenge. For example, the thermal conductivity of polydimethylsiloxane (PDMS)-based TIMs can be limited by defects and structural disorder within the polymer, which can become scattering sites for the heat carrier. These defects can be caused by undesirable crosslinking, insufficient adhesion, and crack formation in the cured TIM. Therefore, materials and technologies for preventing or repairing defects in polymer and polymer composite TIMs can lead to improved performance and reliability of semiconductor packaging. Summary of the Invention

[0004] Various embodiments relate to thermal interface materials (TIMs) comprising hydroxyl-terminated polysiloxanes blended with a catalyst generator. When the catalyst generator is activated by a thermal stimulus, it catalyzes the breaking of silicon-oxygen bonds in the hydroxyl-terminated polysiloxane. For example, the thermal stimulus may be in the range of 160-200°C. The blend may contain about 1% by weight of the catalyst generator. The catalyst generator may be a salt that forms 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in response to a thermal stimulus. For example, the catalyst may be triazabicyclodecene, pyridine, or tetra-n-butylammonium fluoride. In some embodiments, the hydroxyl-terminated polysiloxane is a hydroxyl-terminated polydimethylsiloxane. The TIM may also contain thermally conductive fillers. In some embodiments, the TIM can be reworked by applying a thermal stimulus to repair voids, cracks, and other defects. Therefore, the TIM can improve package yield and lifetime and facilitate the expansion of multi-chip modules.

[0005] Other embodiments relate to methods of providing TIM, including blending a hydroxyl-terminated polysiloxane with a catalyst generator that, when activated by thermal stimulation, breaks silicon-oxygen bonds. Various embodiments also relate to methods of providing a semiconductor package containing a TIM. Further embodiments relate to semiconductor packages containing TIM and computing devices including such semiconductor packages. The reworkability of TIMs can advantageously allow for the repair of defects in the TIM. Furthermore, the use of TIMs can facilitate the expansion of multi-chip modules. TIMs can provide increased yield and lifespan for semiconductor packages and computing devices. Attached Figure Description

[0006] The accompanying drawings included in this application are incorporated in and form part of the specification. They illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure. The drawings are merely illustrative of certain embodiments and do not limit the scope of the disclosure.

[0007] Figure 1A This is a flowchart illustrating a process for fabricating an electronic device having a reworkable thermal interface material (TIM) according to some embodiments.

[0008] Figure 1B This is a flowchart illustrating the process of re-curing a TIM layer according to some embodiments.

[0009] Figure 2 This is a block diagram illustrating a portion of an electronic device module containing a reworkable TIM according to some embodiments.

[0010] Figure 3A This is a chemical structure diagram showing an example of a polysiloxane having substituted cycloaddition units.

[0011] Figure 3B This illustrates heavy-duty polysiloxanes (such as...) according to some embodiments. Figure 3A The diagram shows the chemical reaction of the process of polysiloxane (as shown).

[0012] Figure 4 This is a chemical reaction diagram illustrating experimental examples of thermal stability testing of polysiloxanes according to some embodiments.

[0013] Figure 5A This is a chemical structure diagram showing siloxanecyclopentadiene dimers according to some embodiments.

[0014] Figure 5B This is a chemical structure diagram illustrating an example polysiloxane having a thermally reversible cyclopentadiene dimer unit according to some embodiments.

[0015] Figure 6 This is a chemical structure diagram illustrating a polysiloxane having furan and maleimide groups capable of forming thermally reversible dimer units according to some embodiments.

[0016] Figure 7A The proton nuclear magnetic resonance (NMR) of the first trifunctional furan crosslinker is shown. 1 1H NMR spectrum and corresponding chemical structure diagram.

[0017] Figure 7B The second trifunctional furan crosslinking agent is shown. 1 H NMR spectrum and corresponding chemical structure diagram.

[0018] Figure 8A This is a chemical reaction diagram illustrating the Diels-Alder reaction between a second trifunctional furan crosslinking agent and N-methylmaleimide according to some embodiments.

[0019] Figure 8B It is shown in the monitoring Figure 8A The experimental example shown is a set of results obtained at three time intervals. 1 HNMR spectrum.

[0020] Figure 9A This is a chemical reaction diagram illustrating the formation of a thermally reversible crosslinked network according to some embodiments.

[0021] Figure 9B It shows through Figure 9A The figure shows the experimental results obtained from the dynamic mechanical analysis (DMA) of the cross-linked network.

[0022] Figure 10A This is a chemical reaction diagram illustrating the process of reprocessing TIM by thermally activating a latent catalyst according to some embodiments.

[0023] Figure 10B This is a set of chemical reaction diagrams illustrating examples of salts that can be used as catalyst generators according to some embodiments.

[0024] While the invention is susceptible to various modifications and alternatives, some details thereof have been shown by way of example in the accompanying drawings and will be described in detail. However, it should be understood that it is not intended to limit the invention to the specific embodiments described. Rather, it is intended to cover all modifications, equivalents, and alternatives that fall within the spirit and scope of the invention. Detailed Implementation

[0025] Embodiments of the present invention generally relate to thermal interface materials (TIMs), and more specifically, to polymer composite TIMs. However, this disclosure is not necessarily limited to such applications, and many aspects of this disclosure will become clear from the discussion of examples in this context.

[0026] Various embodiments of this disclosure are described herein with reference to the accompanying drawings, wherein similar numerals refer to the same components. Alternative embodiments may be conceived without departing from the scope of this disclosure. It should be noted that various connections and positional relationships (e.g., above, below, adjacent, etc.) between elements are illustrated in the following description and drawings. Unless otherwise stated, these connections and / or positional relationships may be direct or indirect, and this disclosure is not intended to be limited in this respect. Thus, coupling of entities may refer to direct or indirect coupling, and positional relationships between entities may be direct or indirect positional relationships. As an example of an indirect positional relationship, the description refers to the formation of layer "A" on layer "B" including the case where there are one or more intermediate layers (e.g., layer "C") between layer "A" and layer "B," provided that the relevant characteristics and functionality of layer "A" and layer "B" are not substantially altered by the intermediate layers.

[0027] The following definitions and abbreviations are used to interpret the claims and the specification. As used herein, the terms "comprising," "including," "having," or "containing," or any other variation thereof, are intended to cover non-exclusive inclusion. For example, an ingredient, mixture, process, method, article, or apparatus that comprises a list of items is not necessarily limited to those items, but may include other items not expressly listed or inherent to such ingredient, mixture, process, method, article, or apparatus.

[0028] For descriptive purposes, the terms "above," "below," "right," "left," "vertical," "horizontal," "top," "bottom," and their derivatives shall, in this text, be used in relation to the structures and methods described, as oriented as shown in the accompanying drawings. The terms "overlaying," "on top of," "above," "on," "located on," or "located on top of" mean that a first element (such as a first structure) is present on a second element (such as a second structure), wherein an intermediate element (such as an interface structure) may exist between the first and second elements. The term "direct contact" means that the first element (such as a first structure) and the second element (such as a second structure) are connected at the interface between the two elements without any intermediate conductive, insulating, or semiconductor layer. It should be noted that the term "selective towards," such as, for example, "the first element is selective towards the second element," means that the first element can be etched, while the second element can be used as an etch stop.

[0029] As used in this article, the articles "a" and "an" preceding an item or component ("a") are intended to be non-restrictive in terms of the number of instances (i.e., occurrences) of the item or component. Therefore, "a" and "an" ("a") should be understood to contain one or at least one, and the singular form of an item or component also contains the plural, unless the number clearly indicates the singular.

[0030] As used herein, the terms "invention" or "the present invention" are non-limiting terms and are not intended to refer to any single aspect of a particular invention, but rather to cover all possible aspects described in the specification and claims.

[0031] Unless otherwise stated, ranges (e.g., time, concentration, temperature, etc.) referred to herein include both endpoints and all values ​​in between. Unless otherwise stated, the use of tildes (~) or terms such as "about," "substantially," "approximately," "slightly less than," and variations thereof is intended to include the degree of error associated with a measurement of a particular quantity based on equipment available at the time of filing this application. For example, "about" may include a range of ±8%, 5%, 2%, or ≤1% of the endpoints of a given value, a range of values, or a range of one or more values. Unless otherwise stated, such terms, when used with a range, apply to both ends of that range (e.g., "about 1g – 5g" should be interpreted as "about 1g to about 5g"), and when used with a list of ranges, apply to each range in the list (e.g., "about 1g – 5g, 5g – 10g, etc." should be interpreted as "about 1g to about 5g, about 5g to about 10g, etc."). As used herein, n, m, l, and p represent integers greater than or equal to 1. This article provides example ranges of these integers for polymer / crosslinker repeating units, methylene groups, etc., but these ranges can cover any number of units suitable for the component. For example, n dimethylsiloxane units can represent any appropriate molecular weight (MW) of polydimethylsiloxane (e.g., for TIM applications).

[0032] As used herein, the term "aliphatic" encompasses the terms alkyl, alkenyl, or ynyl. Aliphatic radicals or groups can have any degree of saturation, such as groups having only carbon-carbon single bonds ("alkyl" or "alkylene"), groups having one or more carbon-carbon double bonds ("alkenyl"), groups having one or more carbon-carbon triple bonds ("ynyl"), and groups having a mixture of carbon-carbon single, double, and / or triple bonds.

[0033] As used herein, the term "alkyl" refers to a saturated aliphatic hydrocarbon group containing at least one carbon atom (e.g., C1–C4, C1–C6, or C1–C8 alkyl). Alkyl groups can be straight, branched, cyclic, or any combination thereof. Unless otherwise specifically limited, the term "alkyl" as used herein, as well as derived terms such as "alkoxy" and "thioalkyl," encompasses straight-chain, branched, and cyclic moieties within their scope. If an alkyl radical is further bonded to another atom, it becomes an alkylene radical or alkylene group. In other words, the term "alkylene" also refers to a divalent linear or branched alkyl group. For example, -CH2CH3 is ethyl, while -CH2CH2- is ethylene. The term "alkylene," alone or as part of another substituent, refers to a saturated straight-chain or branched divalent hydrocarbon group obtained by removing two hydrogen atoms from a single carbon atom or two different carbon atoms of a starting alkane.

[0034] Examples of alkyl radicals / partial or alkyl groups include methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, and 1-ethyl-2-methylpropyl. The alkyl or alkylene groups defined above may be unsubstituted or substituted with one or more substituents, as described below.

[0035] As used herein, the term "cyclic" refers to a cyclic compound or group comprising at least three carbon atoms, and the bonds between pairs of adjacent atoms can all be of the specified single bond type (involving two electrons), or some can be double or triple bonds (with four or six electrons, respectively). Examples of cyclic aliphatic groups may include phenyl, saturated cycloalkyl (e.g., cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl), etc.

[0036] As used herein, the term "amine" or "amino" includes compounds in which a nitrogen atom is covalently bonded to at least one carbon or heteroatom. The term "amine" or "amino" includes -NH2 and also includes substituted portions. The term includes "alkylamino," which includes groups and compounds in which nitrogen is bonded to at least one additional alkyl group (e.g., secondary or tertiary amines). As used herein, the term "imino" group or residue means a divalent group =NR, where R represents H or an alkyl group as defined herein. As used herein, the term "imide" refers to a group or compound having a nitrogen atom covalently bonded to two carbonyl groups. As used herein, the term "furan" refers to a group or compound having a five-membered aromatic ring containing four carbon atoms and one oxygen atom.

[0037] As described herein, optionally, the compounds of this disclosure may be substituted with one or more substituents (as generally indicated above, or as exemplified by a particular class, subclass, and species of this disclosure). As described herein, optionally, any portion above or any portion described below may be substituted with one or more substituents described herein.

[0038] In the context of this disclosure, the term "(substituted)" means that one or more hydrogen atoms of the indicated radical or group are independently replaced by the same or different substituent(s). Furthermore, specifically, the term "(substituted)" provides one or more substituents (e.g., two, three, or more) commonly used in the art. However, it is generally known that substituents should be selected such that they do not adversely affect the useful properties of the compound or its function.

[0039] In the context of this disclosure, suitable substituents in some embodiments may include halogen groups, perfluoroalkyl groups, perfluoroalkoxy groups, alkyl groups, alkenyl groups, alkynyl groups, hydroxyl groups, oxo groups, mercapto groups, alkylthio groups, alkoxy groups, aryl or heteroaryl groups, aryloxy or heteroaryloxy groups, aralkyl or heteroarylalkyl groups, arylalkoxy or heteroarylalkoxy groups, amino groups, alkyl and dialkylamino groups, carbamoyl groups, alkyl carbonyl groups, carboxyl groups, alkoxy carbonyl groups, alkylamino carbonyl groups, dialkylamino carbonyl groups, aryl carbonyl groups, aryloxy carbonyl groups, alkyl sulfonyl groups, aryl sulfonyl groups, cycloalkyl groups, cyano groups, C1 to C6 alkylthio groups, arylthio groups, nitro groups, ketol groups, acyl groups, borate esters or borate groups, phosphate groups or phosphoryl groups, aminosulfonyl groups, sulfonyl groups, sulfinyl groups, and combinations thereof.

[0040] In other embodiments, the substituents or substituent groups may include halogens, hydroxyl groups, alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, -NH2 groups, amino groups (primary, secondary, or tertiary), nitro groups, mercapto groups, thioether groups, imino groups, cyano groups, amide groups, phosphonate groups, phosphine groups, carboxyl groups, thiocarbonyl groups, sulfonyl groups, sulfonamide groups, ketyl groups, aldehyde groups, ester groups, acetyl groups, acetoxy groups, carbamoyl groups, oxygen (O); haloalkyl groups (e.g., trifluoromethyl); aminoacyl and aminoalkyl groups; carbocyclic cycloalkyl groups, which may be monocyclic or fused or non-fused polycyclic (e.g., cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl); or heterocyclic alkyl groups, which may be monocyclic or fused. Polycyclic or non-fused polycyclic compounds (e.g., pyrrolyl, piperidinyl, piperazinyl, morpholinyl, or thiazinyl), carbocyclic or heterocyclic, monocyclic, or fused or non-fused polycyclic aryl groups (e.g., phenyl, naphthyl, pyrrolyl, indolyl, furanyl, thiophene, imidazolyl, oxazolyl, isoxazolyl, thiazolyl, triazolyl, tetrazolyl, pyrazolyl, pyridinyl, quinolinyl, isoquinolinyl, acridineyl, pyrazinyl, pyridazinyl, pyrimidinyl, benzimidazolyl, benzothiophene, or benzofuranyl), -CO2CH3, -CONH2, -OCH2CONH2; -SO2NH2, -OCHF2, -CF3, -OCF3.

[0041] Modifications or derivatives of the compounds disclosed throughout this specification are considered suitable for use in the methods and compositions of this disclosure. Derivatives can be prepared by any method known to those skilled in the art, and the properties of such derivatives can be determined for their desired characteristics. In some respects, "derivative" refers to a chemically modified compound that retains the desired effects of the compound prior to the chemical modification.

[0042] In various embodiments, conventional materials and processing techniques can be used, and therefore such conventional aspects are not described in detail herein. For example, the selection of suitable polysiloxanes, curing conditions, solvents, photosensitizers, pigments, fillers, antistatic agents, flame retardants, defoamers, light stabilizers, and antioxidants can be carried out in a conventional manner.

[0043] For the sake of brevity, conventional techniques related to the manufacture of semiconductor devices and integrated circuits (ICs) may or may not be described in detail herein. Furthermore, the various tasks and process steps described herein may be incorporated into more comprehensive procedures or processes with additional steps or functionalities not described in detail herein. In particular, the various steps in the manufacture of semiconductor devices and semiconductor-based ICs are well-known; therefore, for the sake of brevity, many conventional steps will be mentioned only briefly or omitted entirely without providing details of well-known processes.

[0044] It should also be understood that material compounds will be described according to the listed elements, such as SiN or SiGe. These compounds include different elemental proportions in the compound; for example, SiGe includes Si.x Ge (1-x) Where x is less than or equal to 1, and so on. Furthermore, the compound may contain other elements, and they will still function according to the principles described herein. Compounds with additional elements are referred to herein as alloys.

[0045] Turning now to an overview of techniques more specifically related to aspects of the present invention, electronic packaging components for semiconductor and microelectronic devices can typically contain a variety of polymeric materials, such as underfills, thermal interface materials (TIMs), adhesives, pastes, laminates, etc.

[0046] TIM (Temperature Insulation) is widely used in electronic packaging to enhance thermal conduction across the interface between heat sources and heat sinks. The roughness of the interface surface creates non-contact areas, which, if occupied by air, result in high contact thermal resistance (R0) between the surfaces. c Therefore, using a thermally conductive membrane (TIM) with a much higher thermal conductivity (k) than air to fill the gaps can significantly reduce the contact thermal resistance at the interface between electronic package components. Examples of TIMs can include various metals (e.g., liquids, solders, or foils), filled polymer matrices (polymer composites, greases, gels, etc.), carbon-based materials, and phase change materials (PCMs). Polymer composite TIMs can include a polymer matrix (e.g., PDMS or other polysiloxanes) filled with thermally conductive materials ("fillers") such as graphite, aluminum, aluminum nitride (AlN), alumina, bauxite-aluminum, aluminosilicates, boron nitride (BN), liquid gallium, or alloys thereof. This can be based on factors such as high k and low contact thermal resistance (R). c TIM is chosen for its characteristics such as high adhesion.

[0047] However, TIM needs to meet the growing requirements of high frequency and high integration in electronic devices (such as high k, low R). c High-quality bonding remains a challenge. Degradation of the thermal interface material (TIM) in single-chip modules leads to performance loss and increased thermal resistance. Furthermore, as packaging shifts to multi-chip modules, the likelihood of TIM degradation may be even higher, as greater warpage is frequently observed in multi-chip modules.

[0048] Current TIMs can experience crack formation or material failure, leading to thermal degradation / voidage, affecting device performance, or causing encapsulation components to be rejected. The matrix polymers of existing TIMs are often based on irreversible PDMS crosslinking chemistry. Therefore, once the TIM has cured, reworking the material may be impossible. Instead, it may be necessary to completely replace damaged or ineffective TIM layers. Existing methods attempting to address this problem can complicate the TIM assembly process and bonding, and add additional costs. For example, existing techniques for improving TIM adhesion may include the use of reinforcements or fasteners, which apply stress to the TIM, but these techniques occupy space on the laminate surface. Therefore, components like these can disrupt the fundamental rules of device layout.

[0049] Liquid metal materials (e.g., gallium-based liquid metals) have been shown to provide highly thermally conductive films as filler components in polymer composite TIMs. The dispersion of droplets within a pre-crosslinked polymer matrix film enables the formation of a permeation network dynamically trapped through crosslinking via the polymer network. However, if the polymer network crosslinks in a manner that creates too much distance between the thermally conductive filler regions or between droplets, the contact thermal resistance of the TIM can increase. When this type of crosslinking is irreversible, as in existing polymer composite TIMs, improving filler distribution and conductivity after curing may be impossible.

[0050] Embodiments of this disclosure overcome these and other challenges by providing a TIM that can be reworked when heated to repair voids, cracks, and other defects. In some embodiments, the disclosed TIM can be used without requiring significant modifications to typical packaging processes or components. For example, the TIM can be included in a capped package (e.g., as TIM1 / TIM2) or a direct-mount housing (e.g., as TIM1.5). Furthermore, reworkable TIMs can improve package yield and lifetime, and facilitate the expansion of multi-chip modules.

[0051] Reproducible TIMs can include polymer networks (matrixes) with relaxation pathways (e.g., reversible crosslinking chemistry, dynamic covalent bonds, supramolecular interactions, etc.) that can be used to reversibly "soften" the polymer above a threshold temperature. Reproducible TIMs can be composite films of these polymer networks and thermally conductive fillers (such as metal particles or liquid metal).

[0052] In some embodiments, the relaxation pathway for the TIM polysiloxane chain can be generated by introducing persistent anionic chain ends. For example, reworkable TIMs may include hydroxyl-terminated polysiloxanes blended with a latent organic catalyst that, when activated by thermal stimulation, can cleave the silicon-oxygen bonds in the polymer chain.

[0053] In another embodiment, the relaxation pathway can be generated by incorporating a thermally reversible cycloaddition into the network of polysiloxane chains. For example, the hydride-crosslinked polysiloxane component (e.g., main chain, branches, crosslinking agent, etc.) can be replaced with a polysiloxane component functionalized with diene / dienophilic groups (such as cyclopentadiene monocomponent systems or furan / maleimide derivatives). In another example, the polysiloxane contains siloxane surface functional groups that can reversibly dimerize in response to thermal stimulation to improve surface adhesion. In yet another example, a crosslinked network formed by a Diels-Alder reaction between a bismaleimide and a trifunctional furan crosslinking agent can be blended with the polysiloxane.

[0054] Referring now to the accompanying drawings, similar numbers represent the same or similar elements. Figure 1A This is a flowchart illustrating process 100 for preparing an electronic device having a reworkable thermal interface material (TIM) according to some embodiments. A reworkable TIM can be provided. This is shown in operation 110. As described above, the reworkable TIM can be a polymer composite TIM. The polymer matrix of the reworkable TIM can include polysiloxanes, such as polydimethylsiloxane (PDMS) or other polysiloxanes (e.g., poly(dimethylsiloxane-co-diphenylsiloxane)).

[0055] In some embodiments, the polysiloxane may be functionalized with thermally reversible cycloadditions. Hereinafter, "cycloaddition" and "dimer" are used interchangeably to refer to the product of a Diels-Alder cycloaddition / dimerization reaction. For example, a polysiloxane chain having Diels-Alder end groups may be cured to form a polysiloxane backbone linked by thermally reversible cycloadditions. In another example, the polysiloxane chain may be crosslinked and / or branched via side chains and / or terminal Diels-Alder groups. In some embodiments, the polymer network may comprise thermally reversible cycloadditions in both the backbone and the crosslinked / branched chains.

[0056] In another embodiment, the polymer matrix can be formed by blending the polysiloxane with an immiscible crosslinked network containing thermally reversible cycloadditions, or by surface functionalizing the polysiloxane with thermally reversible cycloadditions. In these embodiments, the polysiloxane can be a conventional polysiloxane (e.g., unsubstituted PDMS) or a reversibly dimerized polysiloxane network as described above. Surface functionalization of the polysiloxane can comprise reversibly dimerized siloxane molecules. Surface functional groups can promote adhesion to the surface of device components. The immiscible crosslinked network can provide covalent (e.g., cycloadditions) and physical crosslinking (e.g., crystalline domains, aggregates, etc.), both of which can be reversed in response to thermal stimulation.

[0057] In another embodiment, the reworkable TIM may comprise a polysiloxane blended with a latent organic catalyst, which, when activated by thermal stimulation, can break the silicon-oxygen bonds in the polymer chain. This will be referenced. Figure 10A and 10B Let's discuss this in more detail.

[0058] Reworkable TIMs with varying viscosities, curing temperatures, thermal conductivity, and other properties can be provided by changing the polysiloxane chain length, crosslinking / branching, filler, number / type of reversible cycloaddition units, and catalyst generator concentration. Reworkable TIMs may also contain thermally conductive filler materials within the polysiloxane matrix, such as graphite, aluminum, aluminum nitride (AlN), bauxite, bauxite-aluminum, boron nitride (BN), and liquid metals (e.g., gallium-indium, gallium-indium-tin, etc.). In some embodiments, the TIM contains at least 90 wt.% thermally conductive filler, but this amount can be varied.

[0059] Semiconductor packages can be assembled with reworkable TIMs. This is illustrated in Operation 120. Assembly of the package may include applying and curing a layer of the TIM at the interface between the heat sink and the heat source (e.g., see...). Figure 2 Any suitable technique for assembling a semiconductor package having a polysiloxane-based TIM can be used. Examples of these techniques are known in the art and therefore are not discussed in detail herein. In some embodiments, the assembly of the package may include applying a thermal stimulus to the reworkable TIM after curing. However, the thermal stimulus may be applied after device assembly, such as... Figure 1B As shown.

[0060] Figure 1B This is a flowchart illustrating process 101 of re-curing a TIM layer according to some embodiments. An apparatus containing a cured TIM layer can be provided. This is shown in operation 130. In some embodiments, the apparatus includes at least one layer in process 100 (… Figure 1A The device is a semiconductor package containing a reworkable TIM layer generated in the process. In another embodiment, the device is a computing device containing at least one semiconductor package with a reworkable TIM. In some embodiments, the device is provided when poor performance is found after a period of use (e.g., due to TIM crack formation or loss of adhesion). The device may also be provided in response to the detection of at least one faulty chip during testing.

[0061] Thermal stimulation can be applied at the provided device to rework the TIM. This is illustrated in Operation 140. As used herein, "thermal stimulation" can refer to heat applied at or above a threshold temperature or temperature range sufficient for reworking the TIM polymer (e.g., between about 60–150ºC), but below a temperature that would cause damage to the TIM or other device components. For example, there may be a minimum temperature for reworking the polymer network and a maximum temperature determined based on the thermal stability of the TIM and other device components. Thermal stimulation can be applied for about 10–30 minutes, but the time can vary (e.g., about 5–10 minutes, 10–15 minutes, 15–20 minutes, 30–60 minutes, 1–12 hours, etc.).

[0062] The thermal stimulus can then be removed, allowing the TIM to cool below a threshold temperature (e.g., ambient temperature or any other temperature suitable for device operation). This is illustrated in Operation 150. This allows the reworked TIM polymer to re-cure via a Diels-Alder cycloaddition reaction. Rework can lead to the healing of cracks in the TIM and improved adhesion to the device surface. Furthermore, rework can correct unwanted crosslinking of the polysiloxane.

[0063] Figure 2 This is a block diagram illustrating a portion of an electronic device module 200 containing a reworkable TIM according to some embodiments. Figure 2 Provided the above information about Figure 1A and 1B The illustration is a simplified representation of a semiconductor package that may contain a reworkable TIM. Module 200 may include a package cover 203 (e.g., an integrated heat sink (IHS)) mounted on a semiconductor (silicon chip 206) on a substrate 209. A heat sink 213 may be mounted on the cover 203.

[0064] The capped package of module 200 includes TIM1 / TIM2 layers 216A and 216B (collectively referred to as "TIM layer 216"). TIM1 216A is located at the interface between chip 206 and package cap 203, and TIM2 216B is located at the interface between cap 203 and heat sink 213. In other embodiments, the number / configuration of TIM layers 216 can vary. For example, TIMs such as TIM layer 216 can be included in a package based on direct bonding heterogeneous integration (DBHi) (where the processor chip is directly bonded to the silicon bridge using copper pillars). Although not explicitly stated in Figure 2 As shown, but module 200 may include other device / package components, such as solder balls and underfill between chip 206 and substrate 209, additional semiconductor packages mounted on substrate 209, or any other suitable components known in the art.

[0065] Figure 3AThis is a chemical structure diagram illustrating an example of a polysiloxane (PDMS) 300 having substituted cycloaddition units according to some embodiments of the present disclosure. The polysiloxane 300 can be used in reworkable TIMs (e.g., TIM layer 216). In the structure of the polymer 300, n and m each represent integers greater than or equal to 1, and asterisked bonds represent substituents that can be varied to tune polymer properties. Substituents can be chosen independently, and in some embodiments, are alkyl groups (e.g., methyl, ethyl, propyl, butyl, etc.). However, in other embodiments, at least one asterisked bond can be attached to a hydrogen atom (e.g., when the cyclopentadienyl group is not substituted). In further embodiments, other substituents can be selected according to desired properties (e.g., selected from the example substituents discussed above).

[0066] Polysiloxane 300 can be formed via dimerization of substituted pentadiene end groups on the PDMS chain. The cyclopentadiene end group dimers in the Diels-Alder reaction or in a reversible cycloaddition reaction between a conjugated diene and a substituted olefin ("dienophile"). Changing the diene or dienophile can modulate the effect of temperature on the reaction equilibrium. For example, dienophiles with stronger electron-withdrawing groups can react at lower temperatures. Therefore, in some embodiments, the temperature at which crosslinking / reworking occurs can be tuned by adding electron-withdrawing or electron-donating groups to the cyclopentadiene unit (e.g., at the asterisked bond). In other embodiments, the steric effects of the substituents on the cyclopentadiene species can be altered to tune the threshold temperature for reverse dimerization.

[0067] Figure 3B This is a chemical reaction diagram illustrating process 301 of heavy-duty polysiloxane production according to some embodiments. Such as... Figure 3A The cured TIM containing polysiloxane shown can contain dimerized end groups on the same polysiloxane chain 303, such as Figure 3B As shown. Figure 3B Only one "self-dimerizing" PDMS molecule 303 is shown, but PDMS molecules with varying chain lengths and arrangements can exist in the cured TIM polymer matrix. The presence of self-dimerizing polysiloxane chains can reduce thermal conductivity by disrupting the linear formation of the polymer network. A thermal stimulus can be applied to induce reverse dimerization of the cyclopentadiene dimer units. This is shown in operation 310. Removing the thermal stimulus can lead to the formation of cycloadditions with the cyclopentadiene terminal groups of other PDMS chains in the polymer network. This is shown in operation 320.

[0068] Figure 4This is a chemical reaction diagram illustrating an experimental example 400 of a thermal stability test of reworkable polysiloxane 403 according to some embodiments. Polysiloxane (PDMS) 403 comprises a chain of m chains of n siloxane units linked by DA adducts, where m and n are integers greater than 1. In the experimental example, m ranges from approximately 3 to 5, and the molecular weight of the polysiloxane ranges from approximately 180 to 13,000 g / mol. In operation 410, polymer 403 is cured in a nitrogen (N2) purged polyimide oven under slight vacuum at a temperature range of 65–245ºC. The temperature is increased from 65ºC at a rate of 5ºC / min and then held at 245ºC for approximately 10 minutes. Curing within this temperature range results in the formation of p trimers (where p is an integer greater than 1) on at least two cyclopentadiene end groups of the polysiloxane 403 molecules. In operation 420, the trimer polymer 406 is subjected to a thermal stimulus of approximately 90ºC for approximately 30 minutes. At this temperature, DA dimerization is reversible, but trimerization is not.

[0069] Figure 5A This is a chemical structure diagram illustrating a siloxane Diels-Alder dimer according to some embodiments. Species such as compounds 510–540 can be used as surface functional groups for polysiloxane TIMs. Figure 5A The dimers 510–540 shown contain Diels-Alder adducts that can “dedimerize” in response to thermal stimulation above a threshold temperature (e.g., about 90–120°C). Therefore, if there is a loss of adhesion at the TIM surface, the adhesion at the surface after rework / cooling can be improved by applying thermal stimulation to the device.

[0070] Figure 5B This is a set of chemical structure diagrams illustrating example reworkable polysiloxanes 550–580 having thermally reversible cycloaddition units according to some embodiments. These polysiloxanes 550–580 comprise a polysiloxane (PDMS) backbone chain, wherein the polysiloxane chains are linked by thermally reversible cycloadditions. The backbone chain can be cured by curing with cyclopentadiene end groups or other Diels-Alder end groups (…). Figure 5B Polysiloxane (not shown) is formed using any curing conditions suitable for the polysiloxane. Polysiloxane 550–580 and thermally conductive fillers can be used to form reworkable TIM layers, as described above. Figure 1A – Figure 2For a more detailed discussion. In the figures, n, l, and m are each an integer greater than or equal to 1. For example, n can represent about 34 dimethylsiloxane repeating units, l can represent about 11 methylene (-CH2-) groups, and m can represent about 1–100 PDMS chains linked by cycloaddition units. Although dimethylsiloxane repeating units are illustrated, in some embodiments, at least some of the methyl groups can be replaced by another alkyl group (such as phenyl). For example, poly(dimethylsiloxane-co-diphenylsiloxane) can be used as an alternative to PDMS.

[0071] Figure 6 This is a chemical structure diagram illustrating a group of polysiloxanes 600 having furan and maleimide groups according to some embodiments. The compounds shown comprise bismaleimide PDMS (n=~7–30), bisfuran PDMS (n=~7–30), and side-chain furan PDMS (n=~150), which can react with each other via a Diels-Alder cycloaddition reaction to form furan / maleimide dimer units. In some embodiments, mixtures of PDMS compounds 600 can be cured in the presence of free radical inhibitors (e.g., N,N'-diphenylthiourea, butylated hydroxytoluene, catechol, 4-tert-butylcatechol, 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), 1,4-naphthoquinone, etc.) to prevent irreversible crosslinking via free radical mechanisms. For example, a mixture of PDMS compound 600 and a free radical inhibitor can be cured at about 75ºC (e.g., about 20 hours). The ratio of bis-maleimide-PDMS:bis-furan-PDMS:side-chain-furan-PDMS in the mixture can be 1:1:1 or 1:0.5:0.5, but this ratio can be adjusted based on, for example, the desired thermal properties and viscosity of the resulting TIM.

[0072] This reaction can produce a polymer network ( Figure 6 (Not shown in the image), it comprises a main chain and / or side chains of polysiloxane chains linked by thermally reversible furan / maleimide cycloadducts, and thermally reversible furan / maleimide cycloadducts crosslinked by dimerization of side chains. The cycloadducts in the cured TIM can be "de-dimerized" by a reverse Diels-Alder reaction in the presence of thermal stimulation (e.g., about 100–120ºC for about 10–30 minutes).

[0073] Figure 7A The proton nuclear magnetic resonance (NMR) of the first trifunctional furan crosslinker 703 ("trifunctional crosslinker 703") is shown. 1¹H NMR (or "NMR") spectrum 700 and the corresponding chemical structure diagram. The NMR spectrum 700 was obtained from a solution experiment of the trifunctional crosslinking agent 703 in deuterated chloroform (CDCl₃). The positions of hydrogen atoms on the trifunctional crosslinking agent 703 and their corresponding peaks in the NMR spectrum 700 are shown in [the diagram / image / image]. Figure 7A The symbols are marked as a–f.

[0074] The trifunctional furan crosslinking agent 703, from which NMR 700 was obtained, was synthesized as follows:

[0075] A mixture of 5 g trimesic acid, 10 mL thionyl chloride (SOCl2), and a catalytic amount of dimethylfuran (DMF) was heated under reflux for approximately 3 hours. The remaining SOCl2 was evaporated under reduced pressure to obtain trimesoyl chloride (1,3,-trimesoyl chloride) product. Trimesoyl chloride and approximately ten equivalents (eq.) of furfurylamine were then dissolved in DMF. Pyridine was added dropwise to the solution at approximately 0ºC and stirred for approximately 18 hours. The reaction mixture was then diluted with excess dichloromethane (DCM) and extracted with approximately 1 mol (1M) hydrochloric acid (HCl). The extracted organic phase was dried over magnesium sulfate (MgSO4) and purified by column chromatography (1:1 hexane:ethyl acetate) to obtain trifunctional crosslinking agent 703.

[0076] Figure 7B The second trifunctional furan crosslinker 709 ("trifunctional crosslinker 709") is shown. 1 1H NMR spectrum 706 and corresponding chemical structure diagram. NMR spectrum 706 was obtained using a solution experiment with trifunctional crosslinking agent 709 in CDCl3. The positions of hydrogen atoms on the trifunctional crosslinking agent 709 and their corresponding peaks in NMR spectrum 706 are shown in [data missing]. Figure 7B The symbols are marked as a–e.

[0077] The trifunctional furan crosslinking agent 709, from which NMR 706 was obtained, was synthesized as follows:

[0078] A mixture of 5 g of pyromellitic acid, 10 mL of SOCl2, and a catalytic amount of DMF was heated under reflux for approximately 3 hours. The remaining SOCl2 was evaporated under reduced pressure to obtain pyromellitic tricarboxylic acid chloride. Pyromellitic tricarboxylic acid chloride and approximately 10 eq. of furfuryl alcohol were then dissolved in DMF. Pyridine was added dropwise to the solution at 0ºC and stirred for approximately 18 hours. The reaction mixture was then diluted with excess DCM and extracted with approximately 1 M HCl. The extracted organic phase was dried over MgSO4 and purified by column chromatography (approximately 1:1 hexane:ethyl acetate) to obtain trifunctional furan crosslinking agent 709.

[0079] Figure 8AThis is a chemical reaction diagram illustrating the Diels-Alder reaction 800 between a second trifunctional furan crosslinker 709 and N-methylmaleimide according to some embodiments. In other embodiments, a first trifunctional furan crosslinker 703 can be used for reaction 800. Reaction 800 forms a product 803 having a thermally reversible furan / maleimide cycloaddition. Figure 8B It is under monitoring Figure 8A The experimental example shown is based on reaction 800, with a set of results obtained at three time intervals. 1 806A–806C ¹H NMR spectra (collectively referred to as 806). Figure 8A and 8B In the diagram, hydrogen atoms in the starting material are labeled with letters a–g, and hydrogen atoms in product 803 are labeled with numbers 1–4.

[0080] The first NMR spectrum, 806A, was obtained from the starting mixture of the reactants (trifunctional furan crosslinker 709 and N-methylmaleimide) in deuterated dimethyl sulfoxide (DMSO) of the Diels-Alder reaction 800. The mixture was heated to approximately 80ºC, and the next NMR spectrum, 806B, was obtained from this mixture after approximately 3 hours at that temperature. The third NMR spectrum, 806C, was obtained from the mixture after approximately 48 hours at approximately 80ºC. From this set of NMR spectra 806, it can be seen that the reaction 800 between the second trifunctional crosslinker 709 and N-methylmaleimide proceeds slowly, which may favor the formation of a crosslinked network (e.g., see...). Figure 9A ).

[0081] Figure 9A This is a chemical reaction diagram illustrating the formation of a thermally reversible crosslinked network 900 according to some embodiments. A trifunctional furan crosslinker 903 ("trifunctional crosslinker 903") may be blended with a bismaleimide compound ("bismaleimide") 906. In some embodiments, trifunctional crosslinker 903 represents... Figure 7A and 7B One or both of the crosslinking agents 703 / 709 shown. Figure 9A In the structure of the trifunctional crosslinker 903 shown, X can represent O (ester moiety) or NH (amide moiety). The mixture of bismaleimide 906 and trifunctional crosslinker 903 can be cured at about 60ºC to produce a crosslinked network 909 (represented by wavy bonds attached to the nitrogen atoms of the imide) formed by a Diels-Alder reaction between the trifunctional crosslinker 903 and multiple equivalents of bismaleimide 906. Figure 9AOnly one crosslinking unit of network 909 is shown. However, as those skilled in the art will understand, crosslinked network 909 comprises multiple units of bismaleimide species 906 linked by a trifunctional crosslinking agent 903. The wavy bonds linked to the imide nitrogen atom represent covalent bonds with carbon atoms, as shown in the structure of bismaleimide 906. When the temperature of crosslinked network 909 is raised to (or above) a threshold temperature (e.g., about 100°C), reverse dimerization of the cycloaddition crosslinks can occur. When the temperature decreases, network 909 can re-dimerize.

[0082] In some embodiments, the mixture of bismaleimide 906 and trifunctional furan crosslinking agent 903 can be blended with polysiloxane, for example, in process 100 ( Figure 1A In some embodiments, crosslinking agents 903 and 906 are immiscible in the polysiloxane. Curing the mixture can produce a polymer network containing a crosslinked network 909 (with physical and covalent crosslinks) and the polysiloxane. This polymer network can be used to provide a reworkable TIM, which may also contain thermally conductive fillers. Experimental examples of this process were performed using PDMS and crosslinking agents 903 and 906. In these examples, crosslinking agents 903 and 906 were immiscible in the PDMS, resulting in phase separation. The physical and covalent crosslinks in the crosslinked network 909 / PDMS blend can both be thermally stimulated (e.g., in process 101). Figure 1B The operation (140 sites) is disrupted to allow for rework / healing of the TIM. In some embodiments, rework can be used to improve the distribution of thermally conductive filler throughout the TIM.

[0083] Figure 9B This illustrates the effect of cross-linking network 909 (where X=O, e.g.) Figure 9A Figure 910 shows the experimental results obtained by dynamic mechanical analysis (DMA). The DMA results measure the change in the storage modulus of the crosslinked network 909 upon application of thermal stimulation. A film of crosslinked network 909 (where X=O) was formed by curing a mixture of trifunctional furan crosslinking agent 903 (709) and bismaleimide 906 at 60°C. The change in the storage modulus of the resulting crosslinked network 909 was monitored while cycling between 60°C and 120°C (5°C / min). As shown in Table 910, the storage modulus of the crosslinked network 909 can reversibly decrease in response to the application of thermal stimulation.

[0084] Figure 10AThis is a chemical reaction diagram illustrating a process 1000 for reprocessing a TIM by thermally activating a thermally activated latent catalyst ("organocatalyst generator" or "catalyst generator") according to some embodiments. The organic catalyst generator 1003 (e.g., ≤ 1 wt.%) may be blended with hydroxyl-terminated PDMS 1006. In some embodiments, the hydroxyl-terminated PDMS 1006 / catalyst generator 1003 mixture may be combined with a thermally conductive filler to form a polymer composite TIM. For example, the TIM may comprise a hydroxyl-terminated PDMS 1006 / catalyst generator 1003 matrix having an alumina-bauxite filler. However, various thermally conductive fillers may be used, such as fillers containing graphite, aluminum, aluminosilicates, aluminum nitride, alumina, boron nitride (BN), liquid gallium, or alloys thereof. In other embodiments, the hydroxyl-terminated PDMS 1006 / catalyst generator 1003 mixture can be combined with a conventional TIM (such as Dow Corning® TC-3040 thermally conductive gel (manufactured by Dow, Inc.)) to allow the TIM to be reworked. In some embodiments, the catalyst generator 1003 is a salt that forms DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) when heated to a trigger temperature.

[0085] Figure 10B Figures 1023–1029 are a set of chemical reaction diagrams illustrating examples of salts that can be used as catalyst generators for the formation of DBU according to some embodiments. Figure 10B As shown, the example catalyst generator 1003 in Figures 1023–1029 can form DBU at trigger temperatures of approximately 160ºC, 180ºC, and 200ºC, respectively. In some embodiments, the DBU generator of Figure 1026 is used as process 1000 (… Figure 10A Catalyst generator 1003 in the figure. However, other DBU generators (e.g., those shown in figures 1023 and 1029) may also be used. In some embodiments, other latent catalysts besides DBU may be used. For example, compounds that can be used as catalyst generator 1003 may include salts that produce catalysts such as triazabicyclodecene (1,5,7-triazabicyclo[4.4.0]dec-5-ene, or TBD), pyridine, tetra-n-butylammonium fluoride (TBAF).

[0086] Refer again Figure 10A The TIM containing hydroxyl-terminated PDMS 1006 / catalyst generator 1003 mixture can be cured at a temperature below the trigger temperature of catalyst generator 1003 using any suitable curing conditions. This is illustrated in operation 1010. For example, TIM can be cured at approximately 120ºC.

[0087] The cured TIM can be reworked by activating the catalyst generator 1003 through the application of thermal stimulation. This is illustrated in operation 1020. For example, if the catalyst generator 1003 is Figure 10B The DBU salt shown in Figure 1026 indicates that the thermal stimulus can have a threshold temperature of at least 180ºC. In response to the thermal stimulus, the activated catalyst (… Figure 10A The "cat." in the figure can form an anionic terminus on hydroxyl-terminated PDMS 1006 and break the silicon-oxygen bond. The reaction can continue until the equilibrium reaction stops (at operation 1021).

[0088] The description of various embodiments in this disclosure is for illustrative purposes and is not intended to be exhaustive or limited to the described embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles of the embodiments, their practical application, or technical improvements to technologies found in the market, or to enable others skilled in the art to understand the embodiments described herein.

Claims

1. A thermal interface material (TIM), comprising: A hydroxyl-terminated polysiloxane blended with a catalyst generator, wherein the catalyst generator, when activated by thermal stimulation, catalyzes the breaking of silicon-oxygen bonds in the hydroxyl-terminated polysiloxane.

2. The TIM as claimed in claim 1, wherein the hydroxyl-terminated polysiloxane is a hydroxyl-terminated polydimethylsiloxane.

3. The TIM of claim 1, wherein the catalyst generator is a salt that forms 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in response to the thermal stimulus.

4. The TIM of claim 3, wherein the catalyst generator is a salt forming a catalyst, and the catalyst is selected from the group consisting of triazabicyclodecene, pyridine, and tetra-n-butylammonium fluoride.

5. The TIM as claimed in claim 1, wherein the thermal stimulation has a temperature in the range of 160°C to 200°C.

6. The TIM of claim 1, wherein the catalyst generator comprises 1% by weight of a polysiloxane blend up to hydroxyl-terminated.

7. The TIM as claimed in claim 1, further comprising thermally conductive filler.

8. A method for providing a thermal interface material (TIM), comprising: A hydroxyl-terminated polysiloxane is blended with a catalyst generator, which, when activated by thermal stimulation, catalyzes the breaking of silicon-oxygen bonds in the hydroxyl-terminated polysiloxane.

9. The method of claim 8, further comprising: The TIM is applied at the interface between the heat source and the radiator; as well as The TIM is cured at a temperature below the activation temperature of the catalyst generator.

10. The method of claim 9, further comprising, after the curing, applying a heat stimulus above the activation temperature.

11. The method of claim 8, wherein the thermal stimulation has a temperature in the range of 160°C to 200°C.

12. The method of claim 8, wherein the hydroxyl-terminated polysiloxane is a hydroxyl-terminated polydimethylsiloxane.

13. The method of claim 8, wherein the catalyst generator is a salt that forms 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in response to the thermal stimulus.

14. The method of claim 7, wherein the catalyst generator is a salt forming a catalyst, the catalyst being selected from the group consisting of triazabicyclodecene, pyridine, and tetra-n-butylammonium fluoride.

15. A method for forming a semiconductor package, comprising: A thermal interface material (TIM) is provided, the thermal interface material comprising a hydroxyl-terminated polysiloxane blended with a catalyst generator, the catalyst generator catalyzing the breaking of silicon-oxygen bonds in the hydroxyl-terminated polysiloxane when activated by thermal stimulation.

16. The method of claim 15, further comprising: The TIM is applied at the interface between the heat source and the heat sink of the semiconductor package. as well as The TIM is cured at a temperature below the activation temperature of the catalyst generator.

17. The method of claim 16, further comprising, after the curing, applying a heat stimulus above the activation temperature.

18. The method of claim 17, wherein the catalyst generator forms a catalyst in response to the thermal stimulus, the catalyst being selected from the group consisting of 1,8-diazabicyclo[5.4.0]undec-7-ene, triazabicyclodecene, pyridine, and tetra-n-butylammonium fluoride.

19. A semiconductor package, comprising: Thermal interface material (TIM), wherein the TIM comprises: A hydroxyl-terminated polysiloxane blended with a catalyst generator, wherein the catalyst generator, when activated by thermal stimulation, catalyzes the breaking of silicon-oxygen bonds in the hydroxyl-terminated polysiloxane.

20. The semiconductor package of claim 19, wherein the TIM further comprises thermally conductive filler.

21. The semiconductor package of claim 19, wherein the catalyst generator is a salt of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) formed in response to the thermal stimulus.

22. The semiconductor package of claim 19, wherein the catalyst generator is a salt forming a catalyst, the catalyst being selected from the group consisting of triazabicyclodecene, pyridine, and tetra-n-butylammonium fluoride.

23. A computing device, comprising: At least one semiconductor package comprising a thermal interface material (TIM). The TIM includes: A hydroxyl-terminated polysiloxane blended with a catalyst generator, wherein the catalyst generator, when activated by thermal stimulation, catalyzes the breaking of silicon-oxygen bonds in the hydroxyl-terminated polysiloxane.

24. The computing device of claim 23, wherein the hydroxyl-terminated polysiloxane is a hydroxyl-terminated polydimethylsiloxane.

25. The computing device of claim 23, wherein the catalyst generator is a salt of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) formed in response to the thermal stimulus.

Images