Thermally conductive polymers

Abstract

A polymer comprising repeating units of formula (I): # imgabs0 # X1 and X2 are each independently selected from formulae (II) and (III), with the proviso that at least one of X1 and X2 is a group of formula (III):-(Ar1) m-formula (II)-(Ar2) p-L-(Ar3) q-formula (III) Ar1, Ar2 and Ar3 are independently at each occurrence an arylene or heteroarylene group; m is at least 1; p is at least 1; q is at least 1; and L is a chain of an optionally substituted methylene group and an O atom; one of Y1 and Y2 is CR1, wherein R1 is H or a substituent; and the other of Y1 and Y2 is N; and one of Y3 and Y4 is CR1; and the other of Y3 and Y4 is N.

Description

Background Art

[0001] Thermally conductive materials are used in a variety of applications, including underfill for flip chips to reduce thermally induced stress after flip chip application.

[0002] Suematsu et al., "Polyimine, a C=N Double Bond Containing Polymers: Synthesis and Properties" Polymer Journal, Vol. 15, No. 1, pp. 71-79 (1983) disclose polyimines of the formula:

[0003]

[0004] WO 2022 / 136584 discloses thermally conductive polymers formed by the reaction of dialdehydes and diamines. Summary of the Invention

[0005] The present disclosure provides a polymer comprising repeating units of formula (I):

[0006]

[0007] in:

[0008] X 1 and X 2 are each independently selected from formula (II) and (III), provided that X 1 and X 2 At least one of them is a group of formula (III):

[0009] -(Ar 1 ) m -Formula (II)

[0010] -(Ar 2 ) p -L-(Ar 3 ) q -Formula (III)

[0011] Among them, Ar 1 、Ar 2 and Ar 3 is independently at each occurrence an arylene or heteroarylene group; m is at least 1; p is at least 1; q is at least 1; and L is a chain of optionally substituted methylene groups and O atoms;

[0012] Y 1 and Y 2 One of them is CR 1 , where R 1 is H or a substituent; and Y1 and Y 2 The other of is N; and Y 3 and Y 4 One of them is CR 1 ; and Y 3 and Y 4 The other one is N.

[0013] Optionally, each R 1 H or C 1-20 Hydrocarbyl group.

[0014] Optionally, L contains at least 3 separated Ar 2 and Ar 3 of atoms.

[0015] Optionally, L and Ar 2 and Ar 3 The bonded atoms are each O.

[0016] Optionally, X 1 and X 2 One of them is a group of formula (II), and X 1 and X 2 The other of the group is a group of formula (III).

[0017] Optionally, m is at least 2.

[0018] Optionally, Y 1 and Y 4 Both are CR 1 and the same one in N; and Y 2 and Y 3 Both are the same and CR 1 and another one of N.

[0019] Optionally, Ar 1 、Ar 2 and Ar 3 and alkyl is independently selected at each occurrence from a 6- to 12-membered arylene or an optionally fused 5- or 6-membered heteroarylene.

[0020] Optionally, Ar 1 、Ar 2 and Ar 3 Each occurrence is independently unsubstituted or substituted p-phenylene.

[0021] Optionally, p and q are each 1.

[0022] The present disclosure provides a method of forming a polymer comprising repeating units of formula (I), the method comprising reacting a first monomer of formula M1 and a second monomer of formula M2:

[0023] RG 1 -X 1 -RG 1 M1

[0024] RG 2 -X 2 -RG 2 M2

[0025] Each RG 1 is selected from C(=O)R 1 and NH2, and each RG2 is a second reactive group, which is C(=O)R 1 and the other in NH2.

[0026] The present disclosure provides a film comprising a polymer comprising repeating units of formula (I).

[0027] In some embodiments, the film is formed by a thermal processing method. Optionally, the thermal processing method is selected from extrusion, injection molding, thermal compression bonding, and hot or melt pressing.

[0028] Optionally, the formation of the film comprises depositing a polymer on a surface, heating the deposited polymer to above the phase transition temperature of the polymer, and cooling the polymer to below the phase transition temperature at a rate of no more than 2°C / minute, optionally at a rate of no more than 1°C / minute. Optionally, the polymer is cooled to at least 25°C or at least 50°C below the phase transition temperature at a rate of no more than 2°C / minute, optionally at a rate of no more than 1°C / minute.

[0029] The present disclosure provides an electronic device including the film as described herein disposed on a surface of a functional layer of the electronic device.

[0030] Optionally, the film is arranged in a region between a surface of the functional layer and a first surface of the first chip electrically connected to the functional layer.

[0031] Optionally, the functional layer is a printed circuit board; an interposer; or a second chip.

[0032] Optionally, the electronic device comprises a 3D chip stack.

[0033] The present disclosure provides an apparatus comprising a heat generating device, a heat transfer device configured to transfer heat away from the heat generating device, and a film as described herein disposed between the heat generating device and the heat transfer device.

[0034] The present disclosure provides a heat sink comprising a first surface having fins extending therefrom and an opposing second surface having a film as described herein disposed thereon.

[0035] The present disclosure provides a formulation comprising a first monomer of formula M1 and a second monomer of formula M2 dissolved or dispersed in a solvent or solvent mixture:

[0036] RG 1 -X 1 -RG 1 M1

[0037] RG 2 -X 2 -RG 2 M2

[0038] where X 1 and X 2 As mentioned above; each RG 1 is selected from C(=O)R 1 and NH2 as the first reactive group, and each RG 2 is the second reactive group, which is C(=O)R 1 and the other in NH2.

[0039] The present disclosure provides a method of forming a polymer comprising reacting a polymerization mixture comprising a first monomer of formula M1 and a second monomer of formula M2:

[0040] RG 1 -X 3 -RG 1 M1

[0041] RG 2 -X 4 -RG 2 M2

[0042] Each RG 1 is selected from C(=O)R 1 and NH2 as the first reactive group, and each RG 2 is the second reactive group, which is C(=O)R 1 and the other of NH2; R 1 is H or a substituent; and X 3 and X 4 Each independently selected from the group consisting of formula (II) and formula (III):

[0043] -(Ar 1 ) m -Formula (II)

[0044] -(Ar 2 ) p -L'-(Ar 3 ) q -Formula (III)

[0045] Among them, Ar 1 、Ar 2 and Ar 3 is independently an arylene or heteroarylene group at each occurrence; m is at least 1; p is at least 1; q is at least 1; and L' is an optionally substituted C 1-10 Alkylene, in which one or more non-adjacent C atoms can be replaced by O, S, NR 5 、SiR 6 2. C=O or COO substitution, where R 5 is H or a substituent at each occurrence, and R 6 is independently at each occurrence a substituent,

[0046] And wherein the polymerization mixture comprises a solvent or solvent mixture in which the first monomer, the second monomer, and the aromatic alcohol are dissolved.

[0047] Optionally, the aromatic alcohol is benzene substituted with at least one hydroxyl group.

[0048] Optionally, the solvent or solvent mixture comprises an alkylated benzene.

[0049] Optionally, the solvent or solvent mixture comprises tetrahydrofuran. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 schematically illustrates an electronic device according to some embodiments including a flip chip electrically connected to a substrate;

[0051] Figure 2A Schematically shows the formation Figure 1 The method of the electronic device according to some embodiments, wherein an underfill layer is formed between the substrate and the flip chip;

[0052] Figure 2B Schematically shows the formation Figure 1 The method of an electronic device according to some embodiments, wherein a non-conductive film is applied to the flip chip before being connected to the substrate;

[0053] Figure 3 schematically illustrates a 3D chip stack according to some embodiments;

[0054] Figure 4 Schematic diagram of a substrate used to measure thermal conductivity of a film;

[0055] Figure 5A and Figure 5B Schematically shows the Figure 4 An apparatus for measuring thermal conductivity of a substrate;

[0056] Figure 6A and 6Bis a photograph of a heat-treated film of a polymer according to some embodiments; and

[0057] Figure 7A and 7B is a photograph of a film of a polymer that has not undergone heat treatment, according to some embodiments.

[0058] The accompanying drawings are not drawn to scale and have different viewpoints and perspectives. The accompanying drawings are some implementations and examples. In addition, for the purpose of discussing some embodiments of the disclosed technology, some components and / or operations may be separated into different blocks or combined into a single block. In addition, although the present technology can be subjected to various modifications and alternative forms, specific embodiments are shown by way of example in the accompanying drawings and are described in detail below. However, it is not intended to limit the technology to the specific implementations described. On the contrary, the present technology is intended to cover all modifications, equivalents and alternatives that fall within the technical scope defined by the appended claims. DETAILED DESCRIPTION

[0059] Unless the context clearly requires otherwise, throughout the specification and claims, the words "comprise," "comprising," and the like should be interpreted in an inclusive sense, and not in an exclusive or exhaustive sense; that is, in the sense of "including but not limited to." In addition, when used in this application, the words "herein," "above," "below," and words of similar meaning refer to this application as a whole and not to any particular parts of this application. Where the context permits, words in specific embodiments using the singular or plural may also include the plural or singular, respectively. The word "or" with respect to a list of two or more items encompasses all of the following interpretations of the word: any item in the list, all items in the list, and any combination of items in the list. When used in this application, a reference to a layer being "above" another layer means that the layers may be in direct contact or that one or more intervening layers may be present. When used in this application, a reference to a layer being "on" another layer means that the layers are in direct contact. Reference to a chemical element includes isotopes of that element.

[0060] The teachings of the technology provided herein can be applied to other systems, and need not be applied to the system described below. The elements and actions of the various examples described below can be combined to provide further implementations of the technology. Some alternative implementations of the technology can include not only the additional elements of those implementations mentioned below, but also fewer elements.

[0061] These and other changes can be made to the technology in light of the detailed description that follows. Although this specification describes certain examples of the technology and describes the best mode contemplated, no matter how detailed the specification appears, the technology can be practiced in a variety of ways. As described above, the use of specific terms when describing certain features or aspects of the technology should not be taken to imply that the terms are redefined herein to be limited to any specific characteristics, features, or aspects of the technology associated with the terms. In general, the terms used in the claims that follow should not be interpreted as limiting the technology to the specific examples disclosed in the specification unless the detailed description section explicitly defines the terms. Therefore, the actual scope of the technology covers not only the disclosed examples, but also all equivalent ways of practicing or implementing the technology under the claims.

[0062] To reduce the number of claims, certain aspects of the technology are presented below in certain claim forms, but the applicant contemplates the various aspects of the technology in any number of claim forms.

[0063] In the following description, for the purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of the implementation of the disclosed technology. However, it will be apparent to one skilled in the art that embodiments of the disclosed technology can be practiced without some of these specific details.

[0064] The inventors have found that high thermal conductivity can be provided by a film comprising or consisting of a polymer comprising repeating units of formula (I):

[0065]

[0066] in:

[0067] X 1 and X 2 are each independently selected from formula (II) and (III), provided that X 1 and X 2 At least one of them is a group of formula (III):

[0068] -(Ar 1 ) m - Formula (II)

[0069] -(Ar 2 ) p -L-(Ar 3 ) q - Formula (III)

[0070] Among them, Ar 1 、Ar 2 and Ar 3is an arylene or heteroarylene group at each occurrence; m is at least 1; p is at least 1; q is at least 1; and L is an optionally substituted chain of methylene (—CH 2 —) groups and O atoms;

[0071] Y 1 and Y 2 One of them is CR 1 , where R 1 is H or a substituent; and Y 1 and Y 2 The other of is N; and Y 3 and Y 4 One of them is CR 1 ; and Y 3 and Y 4 The other one is N.

[0072] R 1 Preferably H or C 1-20 Hydrocarbyl groups, more preferably H or C 1-6 Alkyl groups, most preferably H.

[0073] The C and O atoms of L may be arranged in any order. Suitably, no two O atoms are directly adjacent in the chain. Preferably, the terminal atom of L, i.e. the terminal atom of L adjacent to Ar 2 and Ar 3 The bonded atoms are each O.

[0074] One or more H atoms of the methylene group of L may be replaced by one or more substituents. Optionally, one or more H atoms may be replaced by F, C 1-6 Alkyl or C 1-6 Fluoroalkyl substitution.

[0075] Preferably, L contains at least 3 or at least 4 separated Ar 2 and Ar 3 of atoms.

[0076] Exemplary groups L include, but are not limited to, -OCH2CH2O- and -OCH2O-.

[0077] Optionally, X 1 and X 2 Each of is a group of formula (III).

[0078] Preferably, X 1 and X 2 One of them is a group of formula (II), and X 1 and X 2 The other of the group is a group of formula (III).

[0079] Preferably, Y 1 and Y4 Both are CR 1 and the same one in N; and Y 2 and Y 3 Both are the same and CR 1 and the other of N. Preferably, each CR 1 R 1 are the same.

[0080] In a particularly preferred embodiment, X 1 is a group of formula (II); X 2 is a group of formula (III); Y 2 and Y 3 Each is N; and Y 1 and Y 4 Each is CR 1 , where each R 1 Preferably they are the same.

[0081] Preferably, Ar 1 、Ar 2 and Ar 3 is independently selected at each occurrence from a 6- to 12-membered arylene or an optionally fused 5- or 6-membered heteroarylene, such as an unfused 5- or 6-membered heteroarylene or a benzofused 5- or 6-membered heteroarylene. 1 、Ar 2 and Ar 3 Including but not limited to p-phenylene, thiophene, furan and benzobisoxazole, each of which can be independently unsubstituted or substituted with one or more substituents. P-phenylene is preferred.

[0082] m is preferably greater than 1, preferably 2 to 5, more preferably 2 or 3.

[0083] p and q are preferably each independently 1 or 2, more preferably 1.

[0084] Ar 1 、Ar 2 and Ar 3 Each of the R 2 replace.

[0085] Preferably, when present, R 2 independently selected at each occurrence from:

[0086] F;

[0087] CN;

[0088] NO2;

[0089] Branched, straight chain or cyclic C1-40 Alkyl, preferably C 1-20 Alkyl groups in which one or more non-adjacent C atoms may be replaced by O, S, NR 5 、SiR 6 2. C=O or COO substitution; where R 5 Each occurrence is H or a substituent, preferably H or C 1-20 a hydrocarbon group, and R 6 is independently at each occurrence a substituent, optionally C 1-20 a hydrocarbon group; or an aryl or heteroaryl group Ar which is unsubstituted or substituted with one or more substituents; 5 , optionally phenyl, said phenyl being unsubstituted or substituted by one or more selected from F, CN, NO2 and branched, linear or cyclic C 1-20 Alkyl is substituted with a substituent wherein one or more non-adjacent C atoms may be replaced by O, S, NR 5 、SiR 6 2. Replace with C=O or COO.

[0090] Preferably, at least one substituent R 2 , optionally each substituent R 2 C 1-20 Alkyl, C 1-20 Alkoxy or formula –(Ak 1 ) y -(OCH2CH2) z -Ak 2 A group, where Ak 1 C 1-4 alkylene group; y is 0 or 1; z is 1 to 15; and Ak 2 C 1-4 More preferably, R 2 C 1-12 Alkyl or C 1-12 Alkoxy. C 1-12 Alkoxy groups are particularly preferred.

[0091] Exemplary groups -(Ar 1 ) m - including but not limited to groups of formula (IVa) and (IVb):

[0092]

[0093] where R 2 is independently at each occurrence a substituent, and w is independently at each occurrence 0 or a positive integer.

[0094] Preferred groups -(Ar 1 ) m-having the formula (IVb-1):

[0095]

[0096] Ar 2 and Ar 3 Each is preferably an optionally substituted 1,4-phenylene group, more preferably an unsubstituted 1,4-phenylene group.

[0097] The polymer can be 1 and a first monomer having two reactive groups and a first monomer having X substituted with two reactive groups 2 The second monomer is formed by polymerization of the first monomer and the second monomer, wherein the reactive groups of the first monomer and the second monomer react to form 1 With X 2 imine (-CR 1 =N-) bond. Suitable reactive groups for reaction to form imine bonds are aldehydes or ketones (-C(=O)R 1 ) reactive groups, preferably aldehyde reactive groups, and amine (NH2) reactive groups.

[0098] In some embodiments, polymerization occurs between a first monomer of formula M1 and a second monomer of formula M2:

[0099] RG 1 -X 1 -RG 1 M1

[0100] RG 2 -X 2 -RG 2 M2

[0101] Each RG 1 is selected from C(=O)R 1 and NH2, and each RG2 is a second reactive group, which is C(=O)R 1 and the other in NH2.

[0102] Preferably, each RG 1 C(=O)R 1 And each RG 2 is NH2.

[0103] RG 1 With RG 2The reaction between can be catalyzed by a Lewis acid. The Lewis acid can be a Bronsted-Lowry acid. Exemplary catalysts include, but are not limited to, sulfonic acids and salts thereof, such as p-toluenesulfonic acid; trifluoromethanesulfonic acid; and salts thereof; and aromatic alcohols, more preferably benzene, substituted with at least one hydroxyl group and optionally with one or more additional substituents (e.g., one or more C 1-6 alkyl group) substituted.

[0104] An exemplary triflate is scandium triflate, Sc(Trf)3.

[0105] Exemplary aromatic alcohols are unsubstituted or substituted with one or more C 1-6 Phenol substituted with an alkyl group, more preferably one or more methyl groups, such as m-cresol.

[0106] The catalyst may be provided in an amount of 0.01 to 0.3 molar equivalents based on the total moles of monomers.The catalyst is suitably soluble in the solvent or solvent mixture in which the one or more monomers are dissolved.

[0107] Optionally, one or more solvents are selected from the group consisting of 1-12 Alkyl, C 1-12 substituted benzene or naphthalene (substituted with alkyl, F, and Cl); ethers; esters; halogenated alkanes; ketones; sulfoxides; and mixtures thereof. Exemplary solvents include, but are not limited to, toluene, xylene, 1,2,4-trimethylbenzene, mesitylene, tetrahydrofuran, 1-methylnaphthalene, 1-chloronaphthalene, diiodomethane, anisole, N-methylpyrrolidone, 1,2-dimethoxybenzene, dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, and cyclopentanone.

[0108] The polymers as described herein are preferably at least partially crystalline.

[0109] The polymers described herein are preferably linear (unbranched) polymers. Linear polymers can be obtained by having two reactive groups RG as described herein. 1 The monomer has two reactive groups RG 2 The reaction between monomers forms.

[0110] The polymers described herein can undergo π-π stacking when deposited as films.

[0111] Optionally, the polymer as described herein has a thermal conductivity of at least 0.5 Wm -1 K -1 , optionally at least 0.6 or 0.7 Wm -1 K -1 .

[0112] The polystyrene equivalent number average molecular weight (Mn) of the polymers described herein, as measured by gel permeation chromatography, can be between about 1 x 10 3 to 1x10 8 range, and preferably 1x10 4 Up to 5x10 6 The polystyrene equivalent weight average molecular weight (Mw) of the polymer described herein may be 1x10 3 to 1x10 8 , and preferably 1x10 4 to 1x10 7 .

[0113] polymer processing

[0114] The formation of a film comprising a polymer as described herein can include forming a precursor film comprising monomers for forming the polymer, followed by polymerization of the monomers, hereinafter referred to as in situ polymerization. The precursor film can consist of the monomers for forming the polymer, or the precursor film can be a composition comprising one or more additional materials (e.g., a catalyst as described herein and / or thermally conductive particles such as boron nitride particles).

[0115] Preferably, the formation of a film comprising a polymer as described herein includes depositing a polymer formulation comprising a polymer dissolved or dispersed in one or more solvents. The formulation can be composed of a polymer and one or more solvents, or it can include one or more other materials, for example, catalysts as described herein and / or thermally conductive particles such as boron nitride particles. Inorganic thermally conductive particles such as boron nitride as described herein can be substituted with an organic group (optionally an aromatic group, for example, an oligo-(hetero)arylene or poly-(hetero)arylene comprising 1 to 10 arylene or heteroarylene groups). Exemplary surface groups are oligophenylenes, such as biphenyl or terphenyl. The surface groups of thermally conductive particles are disclosed in WO2022 / 207695, the contents of which are incorporated herein by reference.

[0116] In some preferred embodiments of in situ polymerization, the precursor film formation comprises deposition of a monomer formulation comprising monomers dissolved in one or more solvents. According to these embodiments, the in situ polymerization is preferably carried out in solution. The monomer formulation may or may not contain a catalyst.

[0117] The solvent for the monomer or polymer formulation can be selected based on its ability to dissolve the monomer or polymer. Exemplary solvents include, but are not limited to, 1-12 Alkyl, C 1-12substituted benzene or naphthalene (substituted with alkyl, F, and Cl); ethers; esters; halogenated alkanes; ketones; sulfoxides; and mixtures thereof. Exemplary solvents include, but are not limited to, toluene, xylene, 1,2,4-trimethylbenzene, mesitylene, 1-methylnaphthalene, 1-chloronaphthalene, diiodomethane, anisole, tetrahydrofuran, N-methylpyrrolidone, 1,2-dimethoxybenzene, dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, and cyclopentanone.

[0118] The concentration of each monomer or polymer dissolved in the monomer formulation is preferably in the range of about 1 to 50 mg / ml, more preferably about 10 to 40 mg / ml.The monomer or polymer formulation may be heated to effect dissolution of one or more monomers or polymers.

[0119] The polymer precursor film may be heated before and / or after polymerization. In some embodiments, the polymer precursor film may be dried at a temperature of up to about 100° C., optionally 50° C. to 90° C. The dried film may be heated at a temperature above 100° C., optionally in the range of 100° C. to 200° C. The temperature applied before, during, or after drying may be below the melting point of the monomer with the lowest melting point. The temperature applied before, during, or after drying may be at or above the melting point of the monomer with the lowest melting point.

[0120] In some preferred embodiments of in situ polymerization, a monomer formulation comprising monomer particles mixed with a liquid is deposited on a surface to form a polymer precursor film and the film is heated to at least the melting point of the monomer, or if more than one monomer is present, to at least the melting point of the monomer with the lowest melting point. Optionally, the polymer precursor film is heated below the melting point of the lowest monomer to remove the liquid before the heating temperature is raised to at least the melting point. It will be understood that the amount and / or nature of the liquid is such that the monomer particles do not dissolve in the liquid. Preferably, each monomer is slightly soluble or insoluble in the liquid. The liquid can be a single liquid material or a mixture of two or more liquid materials, for example selected from water and C 1-6 The monomer formulation according to these embodiments can be, for example, a suspension or a paste and a suitable deposition method can be selected accordingly.

[0121] A monomer or polymer formulation as described anywhere herein may be deposited by any suitable solution deposition technique including, but not limited to, spin coating, dip coating, jet dispensing, drop casting, spray coating, and doctor blade coating.

[0122] In some embodiments, films formed by in situ polymerization or by depositing a polymer formulation comprising a preformed polymer can be formed directly on the surface of a device or apparatus and can be used as thermal transfer films without further manipulation of the film.

[0123] In other embodiments, after forming the polymer film by in-situ polymerization, deposition of a preformed polymer, or any other method, the polymer film can be processed using a thermal processing technique to form a thermal transfer film on the surface of a device or apparatus. Exemplary thermal processing techniques include, but are not limited to, extrusion, injection molding, thermal compression bonding, and thermal or melt compression molding.

[0124] The thermal transfer film may consist of a polymer, or may contain one or more additional materials, optionally one or more amorphous polymers, such as polystyrene, polyethylene, or polypropylene; and / or one or more thermally conductive materials, such as boron nitride.

[0125] In some embodiments, the film includes thermally conductive particles, such as boron nitride, dispersed therein. In some embodiments, the film does not include any thermally conductive particles.

[0126] Optionally, the thermal transfer film comprising or consisting of a polymer as described herein has a thickness in the range of 1 to 100 microns, preferably 10 to 100 microns.

[0127] application

[0128] Films comprising polymers as described herein can be used in any known application for thermally conductive films. Films as described herein can be disposed between a surface of a heat generating device and a heat transfer device configured to transfer heat away from the heat generating device, such as in any known thermal interface management application.

[0129] It will be appreciated that in this arrangement the membrane is configured to transfer heat from the heat generating device to the heat transfer device.The membrane preferably has a first surface in direct contact with a surface of the heat generating device and / or a second surface opposite the first surface in direct contact with a surface of the heat transfer device.

[0130] The heat generating device may be an electronic device.

[0131] Any passive or active heat transfer device known to those skilled in the art may be used, including but not limited to a heat sink having a surface in contact with the membrane and an opposing surface including one or more heat dissipation features (e.g., fins or tubes or channels configured to transfer heat to a fluid flowing through the tubes or channels). The fluid may or may not undergo a phase change when absorbing heat.

[0132] Preferably, the film is a thermally conductive layer of an electronic device.

[0133] Heat can be transferred from a surface by placing a layer comprising a thermally conductive film as described herein close to the surface. The thermally conductive film can be in direct contact with the surface, or can be separated from the surface by one or more thermally conductive layers.

[0134] The film as described herein may be arranged on a surface of the heat sink that is opposite the surface of the heat sink having the fins extending therefrom. In use, the film may be arranged between the heat sink and the electronic component.

[0135] A film as described herein may be a heat sink layer disposed on a surface of a printed circuit board, such as a PCB for an LED array.

[0136] The films as described herein can be used as non-conductive films, such as underfills for flip chips, including but not limited to 3D stacked multi-chips.

[0137] Figure 1 An electronic device is shown that includes a chip 105; a substrate 101, such as a printed circuit board; and a conductive interconnect 107 between a conductive pad 103 on a surface of substrate 101 and chip 105. An underfill 109 comprising or consisting of a polymer as described herein fills the area between chip 105 and substrate 101. Optionally, the polymer is cross-linked.

[0138] refer to Figure 2A In some embodiments, the formation of the electronic device includes contacting a conductive bump 107′ (e.g., a solder bump) with a conductive pad 103 provided on a substrate 101 (e.g., a printed circuit board) to form an interconnect 107 from the conductive bump 107′. The formation of the underfill 109 including a polymer as described herein includes applying a formulation including one or more monomers to the overlap region between the chip 105 and the substrate 101. Optionally, the polymer is cross-linked after the reaction of the applied formulation and the one or more monomers, for example, by heating and / or UV treatment.

[0139] Reference Figure 2B In some embodiments, a polymer precursor film is formed over the surface of the chip 105 with the conductive bumps 107 ′. Figure 4 B shows complete coverage of the conductive bump 107', but it should be understood that the conductive bump 107' can be partially covered so that a portion of the conductive bump 107' protrudes from the surface of the film 109. The conductive bump 107' is then brought into contact with the conductive pad 103 disposed on the substrate 101 (e.g., a printed circuit board) to form a conductive interconnect between the substrate and the chip. The formation of the conductive interconnect can include applying heat and / or pressure.

[0140] If the polymer of the film 109 is cross-linked, the cross-linking may be performed before, during, or after the conductive bumps 107 ′ are brought into contact with the conductive pads 103 .

[0141] Two or more chips can be connected with a membrane comprising a polymer as described herein disposed between the chips. Figure 3A 3D stack of chips 105 is shown, in accordance with some embodiments, wherein the chips 105 are interposed by an interposer 111 and a non-conductive film 109 disposed between adjacent interposer and chip surfaces and between a substrate 101 (e.g., a printed circuit board) and a first chip of the 3D stack. At least one non-conductive film 109 comprises a polymer as described herein. Vias 115 are formed through the chips 105 and the interposer. The 3D stack may include a heat sink 113 disposed on its surface.

[0142] In some embodiments, a film comprising or consisting of a polymer as described herein may be disposed between the electronic device and the heat sink.

[0143] Examples

[0144] polymer formation

[0145] The polymer was formed by reacting 2',5'-dihexyloxyterphenyl 4,4"-dialdehyde (aldehyde monomer 1) and a diamine monomer as shown below.

[0146]

[0147]

[0148] Synthesis of Example Polymer 1

[0149] Meta-cresol (2 eqv) is added to a stirred solution of monomer B1 (0.288 mg, 1 eqv) and monomer A1 (0.5 g, 1.1 eqv) in a mixture of toluene (5 ml) and THF (50 ml). The mixture is stirred at room temperature for 30 minutes and then concentrated to dryness in a vacuum to form a yellow oil that begins to solidify upon standing. It is resuspended in toluene / THF (about 50 ml) and stirred for 5 minutes and then concentrated to dryness again. The process is repeated a second time, after which the solid is suspended in warm dichloromethane (DCM) and precipitated into methanol. The product is collected as a powdery yellow solid. Yield = 66%.

[0150] Synthesis of Example Polymer 2

[0151] Meta-cresol (2 eqv) is added to a stirred solution of monomer B2 (430 mg, 1 eqv) and monomer A1 (1.0 g, 1.1 eqv) in a mixture of toluene (5 ml) and THF (50 ml). The mixture is stirred at room temperature for 30 minutes and then concentrated to dryness in a vacuum to form a yellow oil that begins to solidify upon standing. It is resuspended in toluene / THF (about 50 ml) and stirred for 5 minutes and then concentrated to dryness again. The process is repeated a second time, after which the solid is dissolved in warm DCM and precipitated into methanol. The product is collected as a powdery yellow solid. Yield = 86%.

[0152] Synthesis of Example Polymer 3

[0153] Meta-cresol (2 eqv) was added to a stirred solution of monomer B3 (424 mg, 1 eqv) and monomer A1 (1.0 g, 1.1 eqv) in a mixture of toluene (5 ml) and THF (50 ml). The mixture was stirred at room temperature for 30 minutes and then concentrated to dryness in a vacuum to form a yellow gel. The mixture was resuspended in toluene (50 ml) and stirred for 5 minutes and then concentrated to dryness again. The process was repeated a second time, after which the solid was dissolved in DCM and precipitated into methanol. The product was collected as a powdery yellow solid. Yield = 71%.

[0154] Synthesis of Example Polymer 4

[0155] Meta-cresol (2 eqv) is added to a stirred solution of monomer B4 (532 mg, 1 eqv) and monomer A1 (1.0 g, 1.1 eqv) in a mixture of toluene (5 ml) and THF (50 ml). The mixture is stirred at room temperature for 1 hour and then concentrated to dryness in a vacuum to form a yellow oil that begins to solidify upon standing. It is resuspended in toluene (about 50 ml) and stirred for 5 minutes and then concentrated to dryness again. The process is repeated a second time, after which the solid is suspended in a DCM / toluene mixture and precipitated into methanol. The product is collected as a powdery yellow solid. Yield = 42%.

[0156] Synthesis of Example Polymer 5

[0157] Meta-cresol (2 eqv) is added to a stirred solution of monomer B5 (536 mg, 1 eqv) and monomer A1 (1.0 g, 1.1 eqv) in a mixture of toluene (5 ml) and THF (50 ml). The mixture is stirred at room temperature for 30 minutes and then concentrated to dryness in a vacuum to form a yellow oil that begins to solidify upon standing. It is resuspended in toluene (about 50 ml) and stirred for 5 minutes and then concentrated to dryness again. The process is repeated a second time, after which the solid is suspended in warm DCM and precipitated into methanol. The product is collected as a powdery yellow solid. Yield = 70%.

[0158] Film deposition

[0159] The polymer inks were prepared by dissolving the polymer at 20 mg / ml in o-dichlorobenzene, optionally applying heat up to 80°C to aid dissolution.

[0160] Film formation

[0161] After dissolving the polymer in the solvent, the resulting ink was rapidly drop-cast onto a substrate at 80°C, as described above for thermal conductivity measurements. A gasket made of a 0.5 mm thick fluorosilicone rubber sheet (Silex Silicones Ltd) and applied to the substrate contained the ink within a defined area (18 x 10 mm rectangle) for the drop-casting procedure. The drop-cast solution was maintained at 80°C for 30 minutes, and then the heat was turned off and the solution was allowed to cool to room temperature. No further annealing step was performed after the solvent of the drop-cast film had evaporated.

[0162] Thermal conductivity measurement

[0163] use Figure 4 The sensor substrate 600 (approximately 25 mm x 25 mm) shown in FIG was used for thermal conductivity measurements as described herein. The substrate comprises a polyethylene naphthalate (PEN) film (Dupont Teonex Q83, 25 μm) with a 200 nm thick heating structure consisting of a 20 μm wide heater line 610, a 500 μm wide bus bar 620 for applying current, and contact pads 640. The sensing structure mirrors the heating structure, except that the heater line is replaced by a 200 μm wide sensor line 630.

[0164] Reference Figure 5A and Figure 5B, the sensor substrate 600 carrying the film to be tested is placed on a temperature-controlled aluminum block, and the temperature can be controlled by software by adjusting the PID system. The aluminum block has a long notch 720 with a width of 1 mm and a depth of about 1 mm. The sensor substrate 600 is placed above the notch so that the central heater circuit 610 is aligned with the center of the notch 720, and the sensor circuit 630 is aligned with the edge of the notch. A PMMA sheet 730 (2 mm thick) with a notch cut that matches the notch cut of the aluminum block 710 is placed on top, and another ordinary PMMA sheet 740 (4 mm thick) is placed on top to close the device. The entire assembly is clamped at position 750 using bolts and nuts. The heater circuit is connected to a source meter device (Keithley 2400) using a 4-wire measuring device. The sensor circuit is connected to a multimeter device (Keithley 2000) using a 4-wire device.

[0165] The assembly's temperature is first stabilized at a predetermined temperature. The resistance of the heater circuit and the temperature sensor is then measured. To measure the heater circuit's resistance without causing excessive heating, a low current is supplied and the voltage is measured in short pulses, allowing time for heat dissipation between pulses. A constant DC current is then passed through the heater circuit to induce resistive heating. The arrangement of the substrate in the assembly causes heat to flow through the substrate and membrane to the aluminum block, which acts as a heat sink, establishing a nearly one-dimensional steady-state heat flux. In this state, the power dissipated in the heater circuit and the resistance of the heater circuit and the temperature sensor are additionally measured. This process is repeated with increasing source current, and the entire process is repeated at the next temperature setpoint.

[0166] The resistance of the heater and sensor lines under no-heat-flux conditions at different temperature set points is used as calibration data in a straight-line fit of resistance and temperature, allowing the temperature of the resistive element to be determined under steady-state heat-flux conditions. Therefore, the temperature gradient ΔT between the heater line and the temperature sensor (aligned with the heat sink) can then be calculated. It is assumed that the power dissipated in the heater line is completely converted into heat energy Q. A straight-line fit is then performed between dT and Q using the additional parameters of the heater line length (L, 14.4 mm) at which the power is measured, the distance between the voltage sensing points, and the gap width (2 W, 1 mm). This provides a measure of the electrical conductivity C of the device under test, affected by losses associated with conductive heat transfer in the substrate and convective and radiative heat transfer to the environment (h).

[0167] To calculate the thermal conductivity κ, the same measurement process was performed on a substrate without any test film (substrate only). It was assumed that the losses were approximately the same when measuring the coated and uncoated substrates. From the device measurement values ​​(C F+S ) minus the conductivity of the substrate (C S ) to adjust these losses. Thermal conductivity (k F) and then by dividing the unique conductivity of the resulting film by the film thickness (d F The film thickness was determined using a digital micrometer by measuring the total thickness and subtracting the substrate thickness.

[0168]

[0169] The results are listed in Table 1.

[0170] Table 1

[0171] polymer L <![CDATA[Thermal conductivity (WmK -1 )]]> Phase transition temperature (℃) Comparative polymer 1 <![CDATA[-CH2CH2-]]> 1.1-1.4 290-350 Comparative polymer 2 <![CDATA[-CH2CH2CH2-]]> 0.6-0.7 100-285 Polymer Example 1 <![CDATA[-OCH2CH2O-]]> 0.9 190-305 Polymer Example 2 <![CDATA[-OCH2O-]]> 0.9 80-310 Polymer Example 3 <![CDATA[-CH2OCH2-]]> 95-130 Polymer Example 4 <![CDATA[-OC5H 10 The-]]> 97-120 Polymer Example 5 <![CDATA[-OC2H4 OC2H4O-]]> 105-210

[0172] The phase transition temperature was determined using a melting point apparatus configured to heat a sample in a tube and detect changes in the sample's transmittance. The ranges given in Table 1 are the ranges observed through video of the sample from the time the material changes from a powder to a liquid or glossy substance to the temperature at which it is a clear liquid.

[0173] As shown in Table 1, although Comparative Polymer 1 has the highest thermal conductivity of the polymers in the table, its relatively high melting point makes it less suitable for processing using thermal processing techniques as described herein.

[0174] Polymer Examples 1 and 2 have a good combination of a relatively low onset phase transition and good thermal conductivity. The data in Table 1 show that relatively low melting points can be achieved by providing chains L having a chain length of 3 or 4 atoms. Surprisingly, for a given chain length of chain L, it was found that the inclusion of oxygen in the chain increased thermal conductivity.

[0175] Furthermore, without wishing to be bound by any theory, polymers in which chain L contains an odd number of chain atoms may pack differently than polymers in which chain L contains an even number of chain atoms.

[0176] Film formation conditions

[0177] After the polymer solution was drop-cast onto a substrate with a fluorosilicone rubber sheet gasket, the substrate was kept on a hot stage at 80°C for 30 minutes and then the heat was turned off. Since this temperature is close to the starting phase transition point of the polymer, it is believed that chain mobility is promoted at this temperature, which leads to more uniform film formation.

[0178] Films of Polymer Example 2 were prepared as described above, except that after 30 minutes at 80°C, the films were cooled more rapidly to room temperature by removing the films from contact with the heated surface.

[0179] refer to Figure 6A and 6B , this rapid cooling results in a film with large domains within the polymer film. In contrast, slow cooling as described above produces a much more uniform film, e.g. Figure 7A and 7BWithout wishing to be bound by any theory, slow cooling at the phase transition onset temperature allows for optimal orientation of the polymer film.

Claims

1. A polymer comprising repeating units of formula (I): in: X 1 and X 2 are each independently selected from formula (II) and (III), provided that X 1 and X 2 At least one of them is a group of formula (III): -(Ar 1 ) m -Formula (II) -(Ar 2 ) p -L-(Ar 3 ) q - Formula (III) Among them, Ar 1 、Ar 2 and Ar 3 is independently an arylene or heteroarylene group at each occurrence; m is at least 1; p is at least 1; q is at least 1; and L is a chain of optionally substituted methylene groups and O atoms; Y 1 and Y 2 One of them is CR 1 , where R 1 is H or a substituent; and Y 1 and Y 2 The other of is N; and Y 3 and Y 4 One of them is CR 1 ; and Y 3 and Y 4 The other one is N.

2. The polymer according to claim 1, wherein each R 1 H or C 1-20 Hydrocarbyl group.

3. The polymer according to claim 1 or 2, wherein L contains at least 3 separated Ar 2 and Ar 3 of atoms.

4. A polymer according to any one of the preceding claims, wherein the ratio of L to Ar 2 and Ar 3 The bonded atoms are each O.

5. A polymer according to any one of the preceding claims, wherein X 1 and X 2 One of them is a group of formula (II), and X 1 and X 2 The other of the group is a group of formula (III). The polymer according to claim 5 , wherein m is at least 2.

7. A polymer according to any one of the preceding claims, wherein Y 1 and Y 4 Both are CR 1 and the same one in N; and Y 2 and Y 3 Both are the same and CR 1 and another one of N.

8. A polymer according to any one of the preceding claims, wherein Ar 1 、Ar 2 and Ar 3 and alkyl is independently selected at each occurrence from a 6- to 12-membered arylene or an optionally fused 5- or 6-membered heteroarylene.

9. A polymer according to any one of the preceding claims, wherein Ar 1 、Ar 2 and Ar 3 Each occurrence is independently unsubstituted or substituted p-phenylene.

10. The polymer according to any one of the preceding claims, wherein p and q are preferably each 1.

11. A method of forming a polymer according to any one of the preceding claims, the method comprising reacting a first monomer of formula M1 with a second monomer of formula M2: RG 1 -X 1 -RG 1 M1 RG 2 -X 2 -RG 2 M2 Each RG 1 is selected from C(=O)R 1 and NH2, and each RG2 is a second reactive group, which is C(=O)R 1 and the other in NH2.

12. A film comprising the polymer according to any one of claims 1 to 10.

13. A method of forming the film of claim 12, wherein the film is formed by a thermal processing method.

14. The method of claim 13, wherein the thermal processing method is selected from the group consisting of extrusion, injection molding, thermocompression bonding, and hot or melt pressing.

15. A method according to claim 13 or 14, comprising depositing the polymer on a surface, heating the deposited polymer to above the phase transition temperature of the polymer, and cooling the polymer to below the phase transition temperature at a rate not exceeding 2°C / min. 16 . An electronic device comprising the film according to claim 12 provided on a surface of a functional layer of the electronic device. 17 . The electronic device according to claim 16 , wherein the film is provided in a region between the surface of the functional layer and a first surface of a first chip electrically connected to the functional layer. 18 . The electronic device according to claim 17 , wherein the functional layer is a printed circuit board; an interposer; or a second chip.

19. The electronic device of claim 16, 17 or 18, wherein the electronic device comprises a 3D chip stack.

20. An apparatus comprising a heat generating device, a heat transfer device configured to transfer heat away from the heat generating device, and the film of claim 12 disposed between the heat generating device and the heat transfer device.

21. A heat sink comprising a first surface having fins extending therefrom and an opposing second surface having the film of claim 12 disposed thereon.

22. A formulation comprising a first monomer of formula M1 and a second monomer of formula M2 dissolved or dispersed in a solvent or solvent mixture: RG 1 -X 1 -RG 1 M1 RG 2 -X 2 -RG 2 M2 where X 1 and X 2 As defined in claim 1 or claim 5; each RG 1 is selected from C(=O)R 1 and NH2 as the first reactive group, and each RG 2 is the second reactive group, which is C(=O)R 1 and the other in NH2.

23. A method of forming a polymer, the method comprising reacting a polymerization mixture comprising a first monomer of formula M1 and a second monomer of formula M2: RG 1 -X 3 -RG 1 M1 RG 2 -X 4 -RG 2 M2 Each RG 1 is selected from C(=O)R 1 and NH2 as the first reactive group, and each RG 2 is the second reactive group, which is C(=O)R 1 and the other of NH2; R 1 is H or a substituent; and X 3 and X 4 Each independently selected from the group consisting of formula (II) and formula (III): -(Ar 1 ) m -Formula (II) -(Ar 2 ) p -L’-(Ar 3 ) q -Formula (III) Among them, Ar 1 、Ar 2 and Ar 3 is independently an arylene or heteroarylene group at each occurrence; m is at least 1; p is at least 1; q is at least 1; and L' is an optionally substituted C 1-10 Alkylene, in which one or more non-adjacent C atoms can be replaced by O, S, NR 5 、SiR 6 2. C=O or COO substitution, where R 5 is H or a substituent at each occurrence, and R 6 is independently at each occurrence a substituent, And wherein the polymerization mixture comprises a solvent or solvent mixture in which the first monomer, the second monomer, and the aromatic alcohol are dissolved.

24. The method of claim 23, wherein the aromatic alcohol is benzene substituted with at least one hydroxyl group.

25. A process according to claim 23 or 24, wherein the solvent or solvent mixture comprises an alkylated benzene.

26. The process of any one of claims 23 to 25, wherein the solvent or solvent mixture comprises tetrahydrofuran.

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