UV-curable resin composition suitable for rewiring layers

Abstract

Hydrophobic, tough, photoimageable functionalized polyimide formulations have been discovered that can be UV-cured and developed with cyclopentanone. The formulations of the present invention can be used as passivation and redistribution layers with photolithographically provided patterning for I / O pad rewiring in fan-out RDL applications. The curable polyimide formulations reduce stress on thin wafers and provide a low-modulus hydrophobic solder mask compared to traditional polyimide formulations. These materials function as protective layers in any application requiring a thin, flexible, hydrophobic polymer, and also possess high tensile strength and high elongation at break.

Description

[Technical Field]

[0001] Related Applications This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Patent Application Serial No. 62 / 966,197, filed January 27, 2020, the entire disclosure of which is incorporated herein by reference.

[0002] FIELD OF THE INVENTION The present invention relates to hydrophobic photoimageable films that can be used in redistribution layers. More specifically, the present invention relates to UV-curable functionalized polyimides in formulations that include high Tg acrylic compounds that can be rapidly UV-cured. The present invention relates to resin formulations that are UV-cured to produce films with high tensile strength and high elongation. Additionally, the films are hydrophobic, have a high glass transition, a low coefficient of thermal expansion, a very low dielectric constant, and a very low dissipation factor. [Background technology]

[0003] Background of the Invention As the electronics industry advances and production of smaller and lighter components increases, the development of new materials gives manufacturers more options to further improve the performance and manufacturability of such components. However, the demand for smaller and more powerful electronic components presents certain challenges.

[0004] The rapid growth of high-density electronic packaging necessitates passivating materials that can be used as redistribution layers. Existing polyimides are the most widely used polymers for this application. They offer excellent tensile strength and elongation, very high thermal stability, toughness, chemical resistance, and resistance to aqueous and high-relative-humidity environments. Polyimides also have a very low dielectric constant, making them ideal for use in high-performance electronics and microelectronics applications. However, traditional polyimides are difficult to process. Conventional polyimides are UV-cured in situ as polyamic acids, then developed and finally hard-baked. The hard-baking process is necessary to close the polyamic acid rings to form the polyimide. This process requires long, high temperatures. For best results, a hard-baking period of several hours at temperatures well above 200°C is required to ensure complete imidization. Incomplete imidization results in significant moisture absorption by the cured polyimide.

[0005] Therefore, there is a need for a passivation material that retains the tensile strength and elongation of traditional polyimides but can be processed at low temperatures without the risk of incomplete ring closure. The material must also have a low coefficient of thermal expansion (CTE) and a relatively high glass transition temperature (Tg). The material must also be fast UV-curable, easily developable in common organic solvents, hydrophobic, and have a low dielectric constant (Dk) and dissipation factor (Df). Polyimides are used very frequently in the fields of photolithography and photoresists; in fact, most wafer passivation uses photocurable polyimide films. Polyimide passivation layers are typically 4–6 microns thick and protect the delicate thin film of metal and oxide on the chip surface from damage during handling and from induced stresses after encapsulation in plastic molding compound. Patterning is simple and straightforward. The inherent low defect density and robust plasma etch resistance of polyimide films allow for the implementation of a single mask process. This allows the polyimide layer to function both as a stress buffer and as a dry etch mask for the underlying silicon nitride layer. Furthermore, polyimide layers are readily used in flip-chip bonding applications, including both C-4 and two-layer bond pad redistribution (BPR) applications. Polyimide layers can be patterned to form structural components in microelectromechanical systems (MEMS).

[0006] Polyimides can also function as interlayer dielectrics in both semiconductors and thin film multichip modules (MCM-Ds). The low dielectric constant, low stress, high modulus, and inherent ductility of polyimide films make them ideal for such multilayer applications. Other uses for polyimides include alignment and / or dielectric layers for displays and structural layers in micromachining applications. In lithium-ion battery technology, polyimide films can be used as protective layers for positive temperature coefficient (PTC) thermistor controllers.

[0007] In the fabrication of microelectronic devices, polyimides are typically applied to substrates as solutions of the corresponding polyamic acid precursors and then thermally cured into smooth, rigid, and intractable polymer films or structural layers. The films can be patterned using lithographic (photographic) processes combined with liquid photoresists. Polyimides are typically formed in situ by the cyclodehydration of the polyamic acid precursors. This imidization step also requires the evaporation of a high-boiling polar aprotic solvent, which can be difficult to drain as the polyimide is formed. This step is sometimes referred to as the "hard bake" because the required temperatures are typically >200°C and take several hours. Eliminating the hard bake step is a goal for electronic applications of polyimide compounds.

[0008] Existing polyimide passivation materials generate high levels of stress on the wafer, which can lead to delamination of the passivation material. Furthermore, thinner silicon wafers can warp during the thermal curing hard bake, resulting in concave or convex wafer surfaces. This phenomenon creates various problems for the semiconductor manufacturing and packaging industries.

[0009] Traditional polyimides have been used as interlayer dielectric materials in microelectronic devices such as integrated circuits (ICs) due to their advantageous dielectric constant, which is lower than that of silicon dioxide. Polyimide-containing formulations are typically applied in liquid form, leveled, and then cured, allowing them to function as planarizing layers in ICs. Nevertheless, traditional polyimide passivation materials are hydrophilic, typically requiring laborious, multi-step processes to form the vias necessary for multilayer electrical interconnects. Even after curing, they tend to absorb moisture, potentially leading to device failure.

[0010] passivation material Materials currently used in passivation and redistribution layers tend to be very hydrophilic and have very high dielectric constants (epoxies, acrylics). While other materials with very high Tg, low CTE, and very good (i.e., low dielectric constants (benzocyclobutenes)) are available, these materials tend to be very brittle, expensive, and difficult to apply. Traditional polyimides can be used to take advantage of their advantageous properties, including high tensile strength at both high and low temperatures and the ability to retain flexibility even at very low temperatures and during repeated thermal cycling from high to low temperatures. Therefore, there is a need for hydrophobic polyimides that are compatible and do not cause warpage of very thin silicon wafers for use in passivation layers.

[0011] Use in photoresists Additionally, there is a continuing need for polyimide films that can be easily developed by photolithography. Generally, photoresists are classified as either negative-tone or positive-tone. A "positive-tone resist" or "positive-tone resist" is one in which the exposed portions become soluble in the developer while the unexposed portions remain insoluble. A "negative-tone resist" or "negative-tone resist" is one in which the exposed portions become insoluble to the photoresist developer while the unexposed portions dissolve. Summary of the Invention [Problem to be solved by the invention]

[0012] Negative-tone photoresists are much more common in the microelectronics industry because they are lower cost, have excellent adhesion to silicon, and have much better chemical resistance. However, development of fine features is much better using positive resists. Improved polyimides are needed for use in high-resolution negative resists that can develop features comparable to those in positive resists. The microelectronics industry continues to demand improvements in polyimide technology to meet increasingly stringent demands. Therefore, materials must be developed to address the requirements of this rapidly evolving industry.

[0013] Summary of the Invention The present invention provides a passivation formulation comprising at least one curable functionalized polyimide compound, wherein the at least one curable functionalized polyimide compound is the product of the condensation of a diamine with an anhydride. In certain embodiments, the condensation reaction produces an anhydride-terminated polyimide, which is further reacted (e.g., with maleic anhydride) to produce a functionalized polyimide (e.g., a maleimide-terminated polyimide). In other embodiments, the condensation reaction produces an amine-terminated polyimide, which is further reacted to produce a functionalized polyimide. By reaction with maleic anhydride, the amine-terminated polyimide produces a functionalized maleimide-terminated polyimide.

[0014] According to the present invention, the diamine may be selected from the group consisting of dimeric diamines, TCD-diamines, 1,10-diaminodecane, 1,12-diaminodecane, 1,2-diamino-2-methylpropane, 1,2-diaminocyclohexane, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 3,3'-diamino-N-methyldipropylamine, diaminomaleonitrile, 1,3-diaminopentane, 9,10- Diaminophenanthrene;4,4'-Diaminooctafluorobiphenyl;3,5-Diaminobenzoic acid;3,7-Diamino-2-methoxyfluorene;4,4'-Diaminobenzophenone;3,4-Diaminobenzophenone;3,4-Diaminotoluene;2,6-Diaminoanthroquinone;2,6-Diaminotoluene;2,3-Diaminotoluene;1,8-Diaminonaphthalene;2,4-Cumenediamine;1,3-Bisaminomethylbenzene;1,3-Bisaminomethylcyclohexane;2-Chloro-1,4-diaminobenzene;1,4-Diamino-2, 5-Dichlorobenzene;1,4-Diamino-2,5-dimethylbenzene;4,4'-Diamino-2,2'-bistrifluoromethylbisphenyl;Bis(amino-3-chlorophenyl)ethane;Bis(4-amino-3,5-dimethylphenyl)methane;Bis(4-amino-3,5-diethylphenyl)methane;Bis(4-amino-3-ethylphenyl)methane;Bis(4-amino-3-ethyl)diaminofluorene;Diaminobenzoic acid;2,3-Diaminonaphthalene;2,3-Diaminophenol;Bis(4-amino-3-methylphenyl)methane;Bis (4-Amino-3-ethylphenyl)methane;4,4'-Diaminophenyl sulfone;4,4'-Oxydianiline;4,4'-Diaminodiphenyl sulfide;3,4'-Oxydianiline;2,2-Bis[4-(3-aminophenoxy)phenyl]propane;2,2'-Bis[4-(4-aminophenoxy)phenyl]propane;1,3-Bis(4-aminophenoxy)benzene;4,4'-Bis(aminophenoxy)bisphenyl;4,4'-Diamino-3,3'-dihydroxybiphenyl;4,4'-Diamino-3,3'-dimethylbiphenyl;4,4'-Diamino-3,3'-dimethyloxybiphenyl;Visaniline M;Visaniline P;9,9-Bis(4-aminophenyl)fluorine;o-Toluidine sulfone;Methylenebis(anthranilic acid);1,3-Bis(4-aminophenoxy)-2,2-dimethylpropane;1,3-Bis(4-aminophenoxy)propane;1,4-Bis(aminophenoxy)butane;1,5-Bis(4-aminophenoxy)butane;2,3,5,6-Tetramethylbenzidine;4,4'-Diaminobenzanilide;2,2-Bis(4-aminophenyl)hexafluoropropane;Polyalkylenedia The diamine may be selected from the group consisting of amines (e.g., Huntsman products Jeffamine D-230, D-400, D2000, and D-4000); 1,3-cyclohexanebis(methylamine); m-xylylenediamine; p-xylylenediamine; bis(4-amino-3-methylcyclohexyl)methane; 1,2-bis(2-aminoethoxy)ethane; 3(4),8(9)-bis(aminomethyl)tricyclo(5.2.1.0)decane; 1,3-diamino-2-propanol; 3-amino-1,2-propanediol; ethanolamine; 3-amino-1-propanol, or combinations thereof. In certain embodiments, the diamine is selected from dimer diamines, TCD-diamines, and combinations thereof.

[0015] According to the present invention, the anhydride may be selected from the group consisting of biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, polybutadiene-grafted-maleic anhydride, polyethylene-grafted-maleic anhydride, polyethylene-alt-maleic anhydride, polymaleic anhydride-alt-1-octadecene, polypropylene-grafted-maleic anhydride, poly(styrene-co-maleic anhydride), 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, bicyclo(2.2.2)oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, and the like. The anhydride may be selected from the group consisting of carboxylic acid dianhydride, diethylenetriaminepentaacetic acid dianhydride, ethylenediaminetetraacetic acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 2,2'-bis(3,3-dicarboxyphenyl)hexafluoropropane dianhydride, 4,4'-bisphenol A diphthalic acid dianhydride, 5-(2,5-dioxytetrahydro)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, or a combination thereof. In certain embodiments, the anhydride is selected from biphenyltetracarboxylic acid dianhydride, pyromellitic acid dianhydride, and a combination thereof.

[0016] In certain embodiments of the present invention, at least one curable functionalized polyimide has a structure according to Formula I:

[0017] [ka]

[0018] wherein each R is independently a substituted or unsubstituted aliphatic, alicyclic, alkenyl, aromatic, or heteroaromatic group; each Q is independently a substituted or unsubstituted aliphatic, alicyclic, alkenyl, aromatic, or heteroaromatic group; and n is an integer having a value from 1 to 100. n can be 1-50, 1-40, 1-30, 1-20, 1-10, 1-9, 1-8, 1-7, 1-6, 1-5, 1-4, 1-3, 1-2, or 1.

[0019] R and / or Q can comprise a C36 moiety. In certain embodiments, at least one R or Q is tricyclodecyldimethyl, norbornyldimethyl, cyclohexanedimethyl; cyclohexyl, isophoronyl; methylenebis(cyclohexyl)dimethyl; or methylenebis(2-methylcyclohexyl)dimethyl.

[0020] Examples of compounds of the present invention include the following compounds and combinations thereof:

[0021] [ka]

[0022] [ka]

[0023] [ka]

[0024] [ka]

[0025] [ka]

[0026] [ka]

[0027] In certain embodiments, the at least one curable functionalized polyimide comprises a blend of curable functionalized polyimides, for example, the blend comprising: a) at least one first curable functionalized flexible polyimide having an average molecular weight of less than 10,000 Da, and b) at least one second curable functionalized polyimide having an average molecular weight of at least about 10,000 Da.

[0028] The at least one first curable functionalized flexible polyimide can have a CTE of at least about 100 ppm / °C, at least about 150 ppm / °C, or at least about 200 ppm / °C, and an average molecular weight of from about 2,000 Da to about 7,500 Da.

[0029] The at least one first curable functionalized flexible polyimide is typically present at about 15% to about 80% by weight of the formulation, for example, at about 15% to about 25% by weight of the formulation.

[0030] The at least one second curable functionalized polyimide can have an average molecular weight of at least about 15,000 Da, at least about 25,000 Da, at least about 40,000 Da, or at least about 50,000 Da, and is typically present at about 45% to about 75% by weight, e.g., about 45% to about 55% by weight. The at least one second curable functionalized polyimide can have a Tg of at least about 100°C, at least about 120°C, at least about 130°C, at least about 140°C, or at least about 150°C. In some embodiments, the at least one second curable functionalized polyimide has a Tg between about 100°C and about 150°C.

[0031] The at least one first curable, functionalized flexible polyimide can be Compound 1, Compound 2, or a combination thereof. The at least one second curable, functionalized polyimide is selected from Compound 3, Compound 4, Compound 5, Compound 6, and combinations thereof. For example, a formulation can include: at least one of Compound 1, Compound 2, or a mixture thereof, and at least one of Compound 3, Compound 4, Compound 5, Compound 6, or a mixture thereof. Combinations contemplated for use in the formulations of the present invention include Compound 1; and Compound 4, Compound 5, or a mixture of combinations thereof.

[0032] The passivating formulation typically includes effective amounts of at least one second curable functionalized polyimide and at least one first curable functionalized flexible polyimide, where effective amount is an amount sufficient to effect UV cure of the formulation.

[0033] Cured aliquots of the passivation formulations of the present invention have a Tg of at least about 90° C., at least about 100° C., at least about 110° C., or at least about 120° C., and typically have an elongation of at least about 40%, at least about 45%, at least about 50%, or at least about 55%. In one embodiment, a cured aliquot of the passivation formulation has a Tg of at least about 100° C. and an elongation of at least about 40%.

[0034] The passivating formulation also includes at least one reactive diluent or co-curing agent, or at least one adhesion promoter, or at least one coupling agent, or at least one UV initiator, or at least one solvent, or any combination thereof.

[0035] In some embodiments, the passivation formulation comprises: a) at least one curable functionalized polyimide compound according to claim 2; b) at least one reactive diluent; c) at least one coupling agent, adhesion promoter, or combination thereof; and d) at least one curing initiator.

[0036] The at least one curable functionalized polyimide compound comprises from about 65% to about 80% by weight or from about 70% to about 80% by weight of the composition.

[0037] The cure initiator can include a UV initiator, which can be 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, dicumyl peroxide; and combinations thereof.

[0038] The at least one reactive diluent can be selected from acrylates, methacrylates, acrylamides, methacrylamides, maleimides, vinyl ethers, vinyl esters, styrene compounds, allyl-functional compounds, epoxies, curable epoxies, olefins, and combinations thereof. In certain embodiments, it is an acrylic monomer such as ethoxylated trimethylolpropane triacrylate, tricyclodecane dimethanol diacrylate, tris(2-acryloxyethyl)isocyanurate, and combinations thereof, and the at least one reactive diluent is selected from the group consisting of ethoxylated trimethylolpropane triacrylate, tricyclodecane dimethanol diacrylate, and combinations thereof.

[0039] In certain embodiments of the present invention, at least one reactive diluent comprises from about 10% to about 30% by weight of the formulation or from about 12% to about 25% by weight of the formulation, typically has a viscosity of less than 200 centipoise, and typically has a Tg greater than about 100°C, greater than about 120°C, greater than about 150°C, greater than 180°C, or greater than about 200°C.

[0040] At least one coupling agent is generally present at about 2% by weight of the formulation, and typically comprises a silane coupling agent, selected from epoxy-functionalized silane coupling agents, amino-functionalized silane coupling agents, and combinations thereof. In certain embodiments, the coupling agent is selected from the group consisting of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KBM-303), N-phenyl-3-aminopropyltrimethoxysilane (KBM-573), and combinations thereof.

[0041] Also provided is a method for passivating an electronic component (e.g., a chip, device, or package) or any portion thereof, comprising the steps of: applying a layer of the passivation formulation of claim 1 to at least a portion of the electronic element; and curing the passivation formulation (e.g., by UV irradiation), thereby passivating the electronic element. Application can be by spin coating.

[0042] There is also provided a passivated electronic component comprising a cured layer of the passivation formulation of claim 1, which can be prepared as described herein.

[0043] Also provided are electronic devices such as semiconductor wafers, chips, wafer level packages, microelectromechanical systems (MEMS), positive temperature coefficient (PTC) passivation layers, fan-out rewiring chips or circuit boards, etc. Also provided are devices having a rewiring layer or passivation layer disposed on at least one surface of the electronic device or any component thereof.

[0044] Also provided by the present invention is a method for rewiring I / O pads of a chip, comprising the steps of: applying a first layer of the passivation compound of claim 1 to the surface of the chip, covering at least the wiring from the I / O pad to the location of the new I / O pad; metallizing the wiring, thereby forming a metallized wiring; applying a second layer of the passivation compound of claim 1 to the surface of the chip, covering at least the metallized wiring; removing the portion of the first layer covering the metallized portion of the new I / O pad; and curing the first and second layers of the passivation compound, thereby rewiring the I / O pads of the chip.

[0045] The first layer of passivation compound can be cured before or after metallization. In some embodiments, the first layer of passivation compound can cover the entire chip surface. Excess first layer of passivation compound can be subsequently removed, such as by photolithography.

[0046] The rerouted chip can be a fan-out wafer level package, where the I / O pads are on the chip and the new I / O pad locations are in the fan-out region. Also provided is a chip prepared in accordance with the method for rerouting I / O pads, which can be included in a device, package, printed circuit board, etc. [Brief explanation of the drawings]

[0047] [Figure 1] Figure 1 is a schematic flow diagram showing the process of passivating a chip. Arrows A and B indicate the steps of the process. [Figure 2] FIG. 2 is a cross-sectional view of a passivated chip prepared by the process shown in FIG. [Figure 3] 3 is a schematic flow diagram illustrating a process for rewiring I / O pads using a redistribution layer (RDL) according to an embodiment of the present invention. Arrows AD indicate steps in the process. [Figure 4A] FIG. 4A is a cross-sectional view of the structure in plane I of FIG. [Figure 4B] FIG. 4B is a cross-sectional view of the structure in plane II of FIG. [Figure 4C] FIG. 4C is a cross-sectional view of the structure in plane III of FIG. [Figure 4D] FIG. 4D is a cross-sectional view of the structure in plane IV of FIG. [Figure 4E] FIG. 4E is a cross-sectional view of the structure in plane V of FIG. [Figure 5] FIG. 5 is a perspective view of a fan-out IC package including an RDL according to one embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view of the structure in plane VI of FIG. [Figure 7A] FIG. 7A is a diagram of a photomask described herein having a pattern of opaque letters and shapes (black) on a UV-transparent ground (white) within an opaque frame (black). [Figure 7B] FIG. 7B is a photomicrograph of the surface of a UV-cured and developed 5 μm thick polyimide film on a silicon wafer with 10 μm vias produced using the photomask shown in FIG. 7A. DETAILED DESCRIPTION OF THE INVENTION

[0048] Detailed Description It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not limiting of the claimed invention. As used herein, the use of the singular includes the plural unless otherwise indicated. As used in the specification and claims, it should be understood that "a" or "an" can mean one or more, depending on the context in which it is used. Thus, a reference to a "compound" can mean that at least one compound molecule is used, but typically refers to multiple compound molecules, which may be of the same or different species. For example, "a compound having a structure according to Formula I below" can refer to a single molecule or multiple molecules included in the formula, as well as all or a subset of the species described by the formula. As used herein, "or" means "and / or" unless otherwise indicated. Furthermore, the use of the term "comprises" and other forms, such as "comprises" and "includes," is not limiting.

[0049] Unless a specific definition is provided, the nomenclature utilized in connection with the analytical, synthetic organic, and inorganic chemistry laboratory procedures and techniques described herein is that known in the art, such as that set forth in the "IUPAC Compendium of Chemical Terminology": "IUPAC Recommendations (The Gold Book)" (McNaught ed.; International Union of Pure and Applied Chemistry, 2nd Ed., 1997) and "Compendium of Polymer Terminology and Nomenclature: IUPAC Recommendations 2008" (Jones et al., eds.; International Union of Pure and Applied Chemistry, 2009). Standard chemical symbols are used interchangeably with the full names represented by such symbols. Thus, for example, the terms "hydrogen" and "H" are understood to have the same meaning. Standard techniques can be used for chemical synthesis, chemical analysis, and formulation.

[0050] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0051] Some specific definitions are listed below. Additional definitions are provided throughout the specification where appropriate. The location of a definition within the specification should not be construed as limiting or differentiating the intent or effect of such definition.

[0052] definition As used herein, "about" means that a number referred to as "about" encompasses the stated number plus or minus 1-10%. For example, "about" 100 degrees can mean 95-105 degrees. Whenever displayed herein, a numerical range, such as "1-20," refers to each integer within the specified range. For example, "1-20 carbon atoms" refers to an alkyl group. The group can include 1 carbon atom, 2 carbon atoms, 3 carbon atoms, and so on, up to 20 carbon atoms (although the term "alkyl" also includes cases where no numerical range of carbon atoms is specified). Ranges expressed as non-integer numbers refer to a value plus or minus 1-10% of the significant value expressed. For example, about 1.50-2.50 mM means a minimum of 1.35 mM, a maximum of 2.75 mM, or any amount therebetween, in increments of 0.01. When a range described herein includes a decimal value, such as "1.2%-10.5%, "the range refers to each decimal value in the smallest increment indicated in the specified range. For example, "1.2% to 10.5%" means the percentage can be 1.2%, 1.3%, 1.4%, 1.5%, etc., up to a maximum of 10.5%, while "1.20%-10.50%" means the percentage can be 1.20%, 1.21%, 1.22%, 1.23%, etc., up to a maximum of 10.50%.

[0053] As used herein, the term "substantially" refers to a large extent or degree. More specifically, "substantially all" or equivalent expressions typically refer to at least about 90%, often at least about 95%, often at least 99%, and more often at least about 99.9%. "Not substantially" refers to less than about 10%, often less than about 5%, and often less than about 1% (such as less than 5%, less than 4%, less than 3%, less than 2%, or 1% or less). "Substantially free" or equivalent expressions typically refer to less than about 10%, often less than about 5%, often less than about 1%, and in certain embodiments less than about 0.1%.

[0054] As used herein, "effective amount" refers to the amount of a compound or other substance that is sufficient in the presence of the remaining ingredients to produce a desired result, such as a reduction in photodegradation and thermooxidative degradation by at least about 50%, usually at least about 70%, typically at least about 90%, often at least about 95%, and most often at least about 99%. In other embodiments of the present invention, an "effective amount" of a compound can refer to that concentration of the compound that is sufficient in the presence of the remaining ingredients to produce a desired result. The effective amount of a compound or other substance can be easily determined by one of ordinary skill in the art.

[0055] As used herein, "adhesive" or "adhesive compound" refers to any substance capable of adhering or bonding two items together. Implicit in the definition of "adhesive composition" or "adhesive formulation" is the fact that the composition or formulation is a combination or mixture of multiple species, components, or compounds, including adhesive monomers, oligomers, and / or polymers. In contrast, "adhesive compound" refers to a single species, such as an adhesive polymer or oligomer.

[0056] More specifically, an adhesive composition refers to an uncured mixture in which the individual components in the mixture retain the chemical and physical properties of the individual components from which the mixture is made. Adhesive compositions are typically malleable and can be a liquid, paste, gel, film, or another form that can be applied to an item so that it can bond to another item.

[0057] "Cured adhesive," "cured adhesive composition," or "cured adhesive formulation" refers to an adhesive component or mixture resulting from a reactive, curable parent compound or mixture that has undergone a chemical and / or physical change that converts the parent compound or mixture into a solid or substantially non-flowable material. A typical curing process may involve crosslinking.

[0058] "Curable" or "curable" means that the original compound or composition can be converted into a solid or substantially non-flowable material by chemical reaction, crosslinking, radiation crosslinking, or a similar process. Thus, the adhesive compounds and compositions of the present invention are curable, but unless otherwise specified, the original compounds and compositions are not cured.

[0059] As used herein, the terms "functionalize," "functionalized," and "functionalization" refer to the addition or inclusion of a moiety ("functional moiety" or "functional group") to a molecule that confers a particular property; often, the functional group has the ability to react with other molecules in a predictable and / or controllable manner. In certain embodiments of the present invention, the functionalization is imparted to the end of the molecule through the addition or inclusion of an end group X. In other embodiments, internal and / or pendant functionalization may be included in the polyimides of the present invention. In some embodiments of the present invention, the functional group is a "curable group" or "curable site," which is a group or site that allows a molecule to undergo chemical and / or physical changes such that the original molecule is converted into a solid or substantially non-flowable material. The "curable group" or "curable site" may facilitate crosslinking.

[0060] As used herein, "thermoplastic" refers to the ability of a compound, composition, or other material (e.g., a plastic) to dissolve in a suitable solvent or to melt into a liquid when heated and freeze into a solid, often to a brittle, glassy state when cooled sufficiently.

[0061] As used herein, "thermosetting" refers to the ability of a compound, composition, or other material to irreversibly "cure," resulting in the formation of a three-dimensional network that has greater strength and less solubility than the uncrosslinked material. Thermosetting materials are typically polymers that can be cured by, for example, heat (e.g., above 200°C), chemical reaction (e.g., epoxy ring-opening, free-radical polymerization), or irradiation (e.g., by visible light, UV light, electron beam radiation, ion beam radiation, or X-ray radiation).

[0062] Thermosetting materials, such as thermosetting polymers, are resins that are typically in a liquid or malleable form before curing, allowing them to be molded or shaped into their final form or used as adhesives. Curing converts the thermosetting resin into a rigid, infusible, insoluble solid or rubber through a crosslinking process. Energy and / or a catalyst are typically added to the uncured thermosetting resin, causing the thermosetting molecules to react at chemically active sites (e.g., unsaturated or epoxy sites), thereby crosslinking the thermosetting molecules into a rigid, three-dimensional structure. The crosslinking process results in the formation of higher molecular weight molecules, resulting in a higher melting point. During the reaction, the polymer's molecular weight increases to a point where its melting point is higher than the surrounding ambient temperature, at which point the polymer enters a solid state.

[0063] As used herein, "crosslinking" refers to the joining of two or more oligomers or longer polymer chains by an element, molecular group, compound, or the crosslinking of another oligomer or polymer. Crosslinking can occur upon heating or exposure to light. Some crosslinking processes can occur at room temperature or even at low temperatures. Increasing crosslink density can change the properties of a material from thermoplastic to thermoset.

[0064] The term "monomer" refers to a molecule that can undergo polymerization or copolymerization, thereby providing a building block for the essential structure of a macromolecule (ie, a polymer).

[0065] The term "prepolymer" refers to a monomer or combination of monomers that have been reacted to a molecular weight state intermediate between that of a monomer and a high molecular weight polymer. Prepolymers can be further polymerized to a fully cured, high molecular weight state via the reactive groups they contain. A mixture of reactive polymer and unreacted monomers is sometimes called a "resin." As used herein, the term "resin" typically refers to a material containing a prepolymer with reactive groups. Generally, a resin is a single type or class of prepolymer, such as an epoxy resin or a bismaleimide resin.

[0066] "Polymer" and "polymeric compound" are used interchangeably herein and generally refer to the combined product of a single chemical polymerization reaction. Polymers are produced by linking monomer subunits in covalently bonded chains. Polymers containing only a single type of monomer are called "homopolymers," while polymers containing a mixture of two or more different monomers are called "copolymers."

[0067] The term "copolymer" includes products obtained by copolymerization of two monomeric species, three monomeric species (terpolymers), four monomeric species (quaterpolymers), and five or more monomeric species. It is well known in the art that copolymers synthesized by chemical methods include, but are not limited to, molecules having the following types of monomeric sequences:

[0068] alternating copolymers containing regularly alternating monomer residues; periodic copolymers having monomer residue types arranged in a repeating sequence; random copolymers having a random sequence of monomer residue types; statistical copolymers with monomer residues arranged according to known statistical rules; Block copolymers have two or more homopolymer subunits linked by covalent bonds; for example, the homopolymer blocks within a block copolymer can be of any length, either uniform or variable length. Block copolymers with two or three distinct blocks are called diblock and triblock copolymers, respectively. Star copolymers have chains of monomer residues with different structural or configurational features linked through a central site.

[0069] Those skilled in the art will understand that a single copolymer molecule may have different regions along its length that can be characterized as alternating, periodic, random, etc. The copolymer product of a chemical polymerization reaction may include individual polymer molecules and fragments, each with a different arrangement of monomer units. Those skilled in the art will be familiar with methods for synthesizing each of these types of copolymers and how to vary the reaction conditions to favor one type over another.

[0070] Furthermore, the length of polymer chains according to the present invention will typically vary over a range or average size produced by a particular reaction. Those skilled in the art will know, for example, methods for controlling the average length of polymer chains produced in a given reaction, and for selecting the size of a polymer after it has been synthesized.

[0071] Unless a more restrictive term is used, "polymer" is intended to encompass homopolymers and copolymers having any arrangement of monomer subunits, as well as copolymers containing individual molecules having multiple arrangements. With respect to length, unless otherwise specified, the length limitations stated for the polymers described herein should be considered as the average length of the individual molecules in the polymer.

[0072] As used herein, "oligomer" or "oligomeric" refers to a polymer having a finite or moderate number of repeating monomer structural units. Oligomers of the present invention typically have from 2 to about 100 repeating monomer units, often from 2 to about 30 repeating monomer units, and often from 2 to about 10 repeating monomer units. They usually have a molecular weight of up to about 3,000.

[0073] Those skilled in the art will appreciate that oligomers and polymers may be incorporated as monomers in subsequent further polymerization or crosslinking reactions, depending on the availability of polymerizable groups or side chains.

[0074] As used herein, the term "solvent" refers to a liquid that dissolves a solid, liquid, or gaseous solute to produce a solution. A "co-solvent" refers to a second, third, etc. solvent used along with a primary solvent.

[0075] As used herein, "aliphatic" refers to any alkyl, alkenyl, cycloalkyl, or cycloalkenyl moiety.

[0076] As used herein, "aromatic hydrocarbon" or "aromatic" refers to a compound having one or more benzene rings.

[0077] As used herein, "alkane" refers to a saturated straight-chain, branched, or cyclic hydrocarbon containing only single bonds. The general formula for an alkane is C n H 2n+2 is.

[0078] "Cycloalkane" refers to an alkane that has one or more rings in its structure.

[0079] As used herein, "alkyl" refers to a straight or branched chain hydrocarbon group having from 1 to about 500 carbon atoms. "Lower alkyl" generally refers to an alkyl group having from 1 to 6 carbon atoms. The terms "alkyl" and "substituted alkyl" refer to substituted and unsubstituted C-C alkyls, respectively.500 Straight-chain saturated aliphatic hydrocarbon groups, substituted and unsubstituted C2-C 200 Straight-chain unsaturated aliphatic hydrocarbon groups, substituted and unsubstituted C4-C 100 Branched saturated aliphatic hydrocarbon groups, substituted and unsubstituted C1-C 500 Contains a branched unsaturated aliphatic hydrocarbon group.

[0080] For example, the definition of "alkyl" includes, but is not limited to, methyl (Me), ethyl (Et), propyl (Pr), butyl (Bu), pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, isopropyl (i-Pr), isobutyl (i-Bu), tert-butyl (t-Bu), sec-butyl (s-Bu), isopentyl, neopentyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, methylcyclopropyl, ethylcyclohexenyl, butenylcyclopentyl, tricyclodecyl, adamantyl, and norbomyl.

[0081] "Substituted" refers to compounds and moieties that have substituents, including, but not limited to, alkyl (e.g., C 1-10 alkyl), alkenyl, alkynyl, hydroxy, oxo, alkoxy, mercapto, cycloalkyl, substituted cycloalkyl, heterocyclic, substituted heterocyclic, aryl, substituted aryl (e.g., aryl C 1-10 Alkyl or aryl C 1-10 alkyloxy), heteroaryl, substituted heteroaryl (e.g., heteroaryl C 1-10 alkyl), aryloxy, C 1-10 Alkyloxy C 1-10 Alkyl, aryl C 1-10 Alkyloxy C 1-10 Alkyl, C 1-10 Alkylthio C 1-10 Alkyl, aryl C 1-10 Alkylthio C1-10 Alkyl, C 1-10 Alkylamino C 1-10 Alkyl, aryl C 1-10 Alkylamino C 1-10 Alkyl, N-aryl-NC 1-10 Alkylamino C 1-10 Alkyl, C 1-10 Alkyl carbonyl C 1-10 Alkyl, aryl C 1-10 Alkyl carbonyl C 1-10 Alkyl, C 1-10 Alkyl carboxy C 1-10 Alkyl, aryl C 1-10 Alkyl carboxy C 1-10 Alkyl, C 1-10 Alkylcarbonylamino C 1-10 Alkyl and aryl C 1-10 Alkylcarbonylamino-C1 -10 Alkyl, substituted aryloxy, halo, haloalkyl (e.g., trihalomethyl), cyano, nitro, nitrone, amino, amido, carbamoyl, =O, =CH-, -C(O)H, -CO)O-, -C(O)-, -S-, -S(O)2, -OC(O)-O-, -NR-C(O), -NR-C(O)-NR, -OC(O)-NR (wherein R is H or lower alkyl), acyl, oxyacyl, carboxyl, carbamate, sulfonyl, sulfonamide, sulfuryl, C 1-10 Alkylthio, Aryl C 1-10 Alkylthio, C 1-10 Alkylamino, Aryl C 1-10 Alkylamino, N-aryl-NC 1-10 Alkylamino, C 1-10 Alkylcarbonyl, ArylC 1-10 Alkyl carbonyl, C 1-10 Alkyl carboxy, aryl C 1-10 Alkyl carboxy, C 1-10 Alkylcarbonylamino, Aryl C 1-10 Alkylcarbonylamino, tetrahydrofuryl, morpholinyl, piperazinyl, and hydroxypyronyl.

[0082] Additionally, as used herein, "C36" and "C36 moiety" refer to all possible structural isomers of a 36-carbon aliphatic moiety, including branched and cyclic isomers with up to three carbon-carbon double bonds in the backbone. One non-limiting example of a C36 moiety is one with a cyclohexane-based core and four long "arms" attached to the core, as shown below:

[0083] [ka]

[0084] As used herein, "cycloalkyl" refers to a cyclic ring-containing group containing from about 3 to about 20 carbon atoms, typically from 3 to about 15 carbon atoms. In certain embodiments, cycloalkyl groups have from about 4 to about 12 carbon atoms, and in still further embodiments, cycloalkyl groups have from about 5 to about 8 carbon atoms. "Substituted cycloalkyl" refers to a cycloalkyl group further bearing one or more substituents as described above.

[0085] As used herein, the term "aryl" refers to an unsubstituted, mono-, di-, or tri-substituted monocyclic, polycyclic, or biaryl aromatic group covalently attached at any ring position capable of forming a stable covalent bond, with certain preferred points of attachment being apparent to those skilled in the art (e.g., 3-phenyl, 4-naphthyl, etc.). "Substituted aryl" refers to an aryl group further bearing one or more substituents as described above.

[0086] Specific examples of moieties included within the definition of "aryl" include, but are not limited to, phenyl, biphenyl, naphthyl, dihydronaphthyl, tetrahydronaphthyl, indenyl, indanyl, azulenyl, anthryl, phenanthryl, fluorenyl, and pyrenyl.

[0087] As used herein, "arylene" refers to a divalent aryl moiety. "Substituted arylene" refers to an arylene moiety bearing one or more substituents as described above.

[0088] As used herein, "alkylaryl" refers to alkyl-substituted aryl groups and "substituted alkylaryl" refers to alkylaryl groups further bearing one or more substituents as set forth above.

[0089] As used herein, "arylalkyl" refers to an aryl-substituted alkyl group, and "substituted arylalkyl" refers to an arylalkyl group further bearing one or more substituents as described below. Examples include, but are not limited to, (4-hydroxyphenyl)ethyl and (2-aminonaphthyl)hexenyl.

[0090] As used herein, "arylalkenyl" refers to aryl-substituted alkenyl groups and "substituted arylalkenyl" refers to arylalkenyl groups further bearing one or more substituents as set forth above.

[0091] As used herein, "arylalkynyl" refers to aryl-substituted alkynyl groups and "substituted arylalkynyl" refers to arylalkynyl groups further bearing one or more substituents as set forth above.

[0092] As used herein, "aroyl" refers to arylcarbonyl species such as benzoyl, and "substituted aroyl" refers to aroyl groups further bearing one or more substituents as set forth above.

[0093] As used herein, "hetero" refers to a group or moiety that includes one or more non-carbon heteroatoms, such as N, O, Si, and S. Thus, for example, "heterocyclic" refers to a cyclic (i.e., ring-containing) group having, for example, N, O, Si, or S as part of the ring structure and having 3 to 14 carbon atoms. "Heteroaryl" and "heteroalkyl" moieties are aryl and alkyl groups, respectively, that include, for example, N, O, Si, or S as part of their structure. The terms "heteroaryl," "heterocycle," or "heterocyclic" refer to a monovalent unsaturated group having a single ring or multiple fused rings of 1-8 carbon atoms and 1-4 heteroatoms selected from nitrogen, sulfur, or oxygen present within the ring.

[0094] The definition of "heteroaryl" includes, but is not limited to: Thienyl, benzothienyl, isobenzothienyl, 2,3-dihydrobenzothienyl, furyl, pyranyl, benzofuranyl, isobenzofuranyl, 2,3-dihydrobenzofuranyl, pyrrolyl, pyrrolyl-2,5-dione, 3-pyrrolinyl, indolyl, isoindolyl, 3H-indolyl, indolinyl, indolizinyl, indazolyl, phthalimidyl (or isoindolyl-1,3-dione), imidazolyl, 2H-imidazolinyl, benzimidazolyl, pyridyl, pyrazinyl, pyridazinyl, pyrimidinyl, triazinyl, quinolyl, iso Quinolyl, 4H-quinolidinyl, cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, 1,8-naphthyridinyl, pteridinyl, carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl, chromanyl, benzodioxolyl, piperonyl, purinyl, pyrazolyl, triazolyl, tetrazolyl, thiazolyl, isothiazolyl, benzthiazolyl, oxazolyl, isoxazolyl, benzoxazolyl, oxadiazolyl, thiadiazolyl, pyrrolidinyl-2,5-dione, inidazolidinyl-2,4-dione, 2- Thioxo-inidazolidinyl-4-one, inidazolidinyl-2,4-dithione, thiazolidinyl-2,4-dione, 4-thioxo-thiazolidinyl-2-one, piperazinyl-2,5-dione, tetrahydro-pyridazinyl-3,6-dione, 1,2-dihydro-[1,2,4,5]tetrazinyl-3,6-dione, [1,2,4,5]tetrazinanyl-3,6-dione, dihydro-pyrimidinyl-2,4-dione, pyrimidinyl-2,4,6-trione, 1H-pyrimidinyl-2,4-dione, 5-iodo-1H-pyrimidinyl-2,4-dione , 5-methyl-1H-pyrimidinyl-2,4-dione, 5-isopropyl-1H-pyrimidinyl-2,4-dione, 5-propynyl-1H-pyrimidinyl-2,4-dione, 5-trifluoromethyl-1H-pyrimidinyl-2,4-dione, 6-amino-9H-purinyl, 2-amino-9H-purinyl, 4-amino-1H-pyrimidinyl-2-one, 4-amino-5-fluoro-1H-pyrimidinyl-2,4-dione, 4-amino-5-methyl-1H-pyrimidinyl-2-one, 2-amino-1,9-dihydro-purinyl-6-one, 1H-[1,2,4] Triazolyl-3-carboxylic acid amide, 2,6-diamino-N6-cyclopropyl-9H-purinyl, 2-amino-6-(4-methoxyphenylsulfanyl)-9H-purinyl, 5,6-dichloro-1H-benzimidazolyl, 2-isopropylamino-5,6-dichloro-1H-benzimidazolyl, 2-bromo-5,6-dichloro-1H-benzimidazolyl, etc. Furthermore, the term "saturated heterocyclic" refers to an unsubstituted, mono-substituted, di-substituted, or tri-substituted monocyclic or polycyclic saturated heterocyclic group covalently bonded at any ring position capable of forming a stable covalent bond, with specific preferred bonding positions being apparent to those skilled in the art (e.g., 1-piperidinyl, 4-piperazinyl, etc.).

[0095] Hetero-containing groups can also be substituted. For example, "substituted heterocyclic" refers to a ring-containing group having from 3 to 14 carbon atoms containing one or more heteroatoms and having one or more substituents as described above.

[0096] As used herein, the term "phenol" includes compounds having one or more phenolic functional groups per molecule, as shown below.

[0097] [ka]

[0098] The terms aliphatic, alicyclic and aromatic, when used to describe phenols, refer to phenols to which aliphatic, alicyclic and aromatic residues or combinations of these backbones are attached by direct bonds or ring fusions.

[0099] As used herein, "alkenyl," "alkene," or "olefin" refers to a straight- or branched-chain unsaturated hydrocarbon group having at least one carbon-carbon double bond and having from about 2 to 500 carbon atoms. In certain embodiments, an alkenyl group has from about 5 to about 250 carbon atoms, from about 5 to about 100 carbon atoms, from about 5 to about 50 carbon atoms, or from about 5 to about 25 carbon atoms. In other embodiments, an alkenyl group has from about 6 to about 500 carbon atoms, from about 8 to about 500 carbon atoms, from about 10 to about 500 carbon atoms, or from about 20 to about 500 carbon atoms, or from about 50 to about 500 carbon atoms. In yet other embodiments, alkenyl groups have from about 6 to about 100 carbon atoms, from about 10 to about 100 carbon atoms, from about 20 to about 100 carbon atoms, or from about 50 to about 100 carbon atoms, and in other embodiments, alkenyl groups have from about 6 to about 50 carbon atoms, from about 6 to about 25 carbon atoms, from about 10 to about 50 carbon atoms, or from about 10 to 25 carbon atoms. "Substituted alkenyl" refers to alkenyl groups further bearing one or more substituents as set forth above.

[0100] As used herein, "alkylene" refers to a divalent alkyl moiety and "oxyalkylene" refers to an alkylene moiety containing at least one oxygen atom in place of a methylene (CH) unit. "Substituted alkylene" and "substituted oxyalkylene" refer to alkylene and oxyalkylene groups further bearing one or more substituents as described above.

[0101] As used herein, "alkynyl" refers to a straight- or branched-chain hydrocarbon group having at least one carbon-carbon triple bond and having from 2 to about 100 carbon atoms, typically from about 4 to about 50 carbon atoms, and often from about 8 to about 25 carbon atoms. "Substituted alkynyl" refers to alkynyl groups further bearing one or more substituents as described above.

[0102] As used herein, "acyl" refers to an alkyl-carbonyl species.

[0103] As used herein, the term "oxetane" refers to a compound having at least one moiety having the following structure:

[0104] [ka]

[0105] As used herein, "aryl" refers to a compound having at least one moiety having the following structure:

[0106] [ka]

[0107] As used herein, "vinyl ether" refers to a compound having at least one moiety having the following structure:

[0108] [ka]

[0109] As used herein, the term "vinyl ester" refers to a compound having at least one moiety having the following structure:

[0110] [ka]

[0111] As used herein, "styrene" and "styrenic" refer to a compound having at least one moiety having the following structure:

[0112] [ka]

[0113] As used herein, "fumarate" refers to a compound having at least one moiety having the following structure:

[0114] [ka]

[0115] As used herein, "propargyl" refers to a compound having at least one moiety having the following structure:

[0116] [ka]

[0117] As used herein, "cyanate" refers to a compound having at least one moiety having the following structure:

[0118] [ka]

[0119] As used herein, "cyanate ester" refers to a compound having at least one moiety having the following structure:

[0120] [ka]

[0121] As used herein, "norbornyl" refers to a compound having at least one moiety having the following structure:

[0122] [ka]

[0123] As used herein, "imide" refers to a functional group having two carbonyl groups attached to a primary amine or ammonia. The general formula for imides of the present invention is:

[0124] [ka]

[0125] A "polyimide" is a polymer of imide-containing monomers. Polyimides are typically linear or cyclic. Non-limiting examples of linear and cyclic polyimides (e.g., aromatic heterocyclic polyimides) are provided below for illustrative purposes.

[0126] [ka]

[0127] [ka]

[0128] As used herein, "maleimide" refers to an N-substituted maleimide having the formula shown below:

[0129] [ka]

[0130] where R is an aromatic, heteroaromatic, aliphatic, or polymeric moiety.

[0131] As used herein, "bismaleimide" or "BMI" refers to a compound in which two imide moieties are linked by a bridge, i.e., a polyimide compound having the general structure shown below.

[0132] [ka]

[0133] where R is an aromatic, heteroaromatic, aliphatic, or polymeric moiety.

[0134] BMI can be cured by an addition reaction rather than a condensation reaction, thus avoiding problems due to the formation of volatile substances. BMI can be cured by the vinyl-type polymerization of a prepolymer terminated with two maleimide groups.

[0135] As used herein, the term "acrylate" refers to a compound having at least one moiety having the following structure:

[0136] [ka]

[0137] As used herein, the term "acrylamide" refers to a compound having at least one moiety having the following structure:

[0138] [ka]

[0139] As used herein, the term "methacrylate" refers to a compound having at least one moiety having the following structure:

[0140] [ka]

[0141] As used herein, the term "methacrylamide" refers to a compound having at least one moiety having the following structure:

[0142] [ka]

[0143] As used herein, "maleate" refers to a compound having at least one moiety having the following structure:

[0144] [ka]

[0145] As used herein, the terms "citraconimide" and "citraconate" refer to compounds having at least one moiety having the following structure:

[0146] [ka]

[0147] As used herein, "itaconimide" and "itaconate" refer to compounds having at least one moiety having the following structure:

[0148] [ka]

[0149] As used herein, "oxazoline" refers to a compound having at least one moiety having the following structure:

[0150] As used herein, "benzoxazine" refers to a moiety containing the following bicyclic structure:

[0151] [ka]

[0152] As used herein, the term "acyloxybenzoate" or "phenyl ester" refers to a compound having at least one moiety having the following structure:

[0153] [ka]

[0154] wherein R is H, lower alkyl, or aryl.

[0155] As used herein, "siloxane" refers to any compound containing an Si-O moiety. Siloxanes can be either linear or cyclic. In certain embodiments, the siloxanes of the present invention contain two or more repeating Si-O units. Exemplary cyclic siloxanes include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and the like.

[0156] As used herein, the terms "halogen," "halide," or "halo" include fluorine, chlorine, bromine, and iodine.

[0157] As used herein, "oxiranylene" or "epoxy" refers to a divalent moiety having the following structure:

[0158] [ka]

[0159] The term "epoxy" also refers to a thermosetting epoxide polymer that cures by polymerization and crosslinking when mixed with a catalyst or "hardener," also called a "curing agent" or "curative." Epoxies of the present invention include, but are not limited to, aliphatic, alicyclic, glycidyl ether, glycidyl ester, glycidyl amine epoxies, and the like, and combinations thereof.

[0160] As used herein, the term "free radical initiator" refers to any chemical species that, upon exposure to sufficient energy (e.g., light or heat), decomposes into uncharged moieties, all of which have at least one unpaired electron.

[0161] As used herein, "photoinitiation" refers to polymerization initiated by light. In most cases, light-induced polymerization utilizes an initiator to generate radicals. The radicals can be one of two types:

[0162] "Type I photoinitiators" (unimolecular photoinitiators). Upon absorbing light, the homolytic bond is broken. "Type II photoinitiators" (bimolecular photoinitiators) consist of a photoinitiator such as benzophenone or thioxanthone and a coinitiator such as an alcohol or amine.

[0163] As used herein, "coupling agent" refers to a chemical species capable of bonding different materials together, particularly to bond materials to mineral surfaces, and also containing polymerizable reactive functional groups to enable interaction with adhesive polymer compositions. Coupling agents are typically bifunctional molecules, with one functional group reacting with the mineral surface and the other functional group reacting with the polymer, bonding the two together. Thus, the coupling agent facilitates bonding of the passivation layer to the substrate to which it is applied.

[0164] As used herein, "diamine" generally refers to a compound having two amine groups or a mixture of compounds each having two amine groups. As used herein, "anhydride" refers to a compound having at least one moiety having the following structure:

[0165] [ka]

[0166] As used herein, "dianhydride" generally refers to a compound having two anhydride groups or a mixture of compounds each having two anhydride groups.

[0167] "Glass transition temperature" or "Tg" is used herein to refer to the temperature at which an amorphous solid, such as a polymer, becomes brittle on cooling or softens on heating. More specifically, it defines a pseudo-second-order phase transition at which a supercooled melt, upon cooling, develops a glassy structure and properties similar to those of a crystalline material, e.g., an isotropic solid material.

[0168] As used herein, "low glass transition temperature" or "low Tg" refers to a Tg of about 50°C or less. As used herein, "high glass transition temperature" or "high Tg" refers to a Tg of at least about 60°C, at least about 70°C, at least about 80°C, or at least about 100°C. As used herein, "very high glass transition temperature" and "very high Tg" refer to a Tg of at least about 150°C, at least about 175°C, at least about 200°C, at least about 220°C or higher. The high glass transition temperature compounds and compositions of the present invention typically have a Tg in the range of about 70°C to about 300°C.

[0169] As used herein, "elastic modulus" or "Young's modulus" is a measure of the stiffness of a material. Within the elastic range, the modulus is the ratio of linear stress to linear strain and can be determined from the slope of the stress-strain curve generated during a tensile test.

[0170] "Coefficient of thermal expansion" or "CTE" is a term of art that describes the thermodynamic properties of a substance. CTE relates to the change in linear dimensions of a material with a change in temperature. As used herein, "α1CTE" or "α1" refers to the CTE at or below Tg, and "α2CTE" refers to the CTE at temperatures above Tg.

[0171] As used herein, "low coefficient of thermal expansion" or "low CTE" refers to a CTE of less than about 50 ppm / °C, typically less than about 30 ppm / °C or less than about 10 ppm / °C.

[0172] As used herein, "high coefficient of thermal expansion" or "high CTE" refers to a CTE greater than about 100 ppm / °C, typically greater than about 150 ppm / °C, or greater than about 200 ppm / °C.

[0173] "Thermogravimetric analysis" or "TGA" refers to a method of testing and analyzing materials to determine the change in weight of a sample being heated in relation to a change in temperature.

[0174] "Onset of decomposition" or "Td" refers to the temperature at which a loss in weight in response to an increase in temperature indicates that the sample is beginning to decompose. "Td(5%)" is the temperature at which 5% of the sample has decomposed. When measured in an air environment, "air" is usually indicated by the abbreviation Td(5%), such as "Td(5%), air."

[0175] As used herein, "breakdown voltage" refers to the minimum voltage that causes a portion of an insulator to become conductive. A "high breakdown voltage" is at least about 100 V to at least about 900 V, e.g., 200 V, 300 V, 400 V, 500 V, 600 V, 700 V, 800 V, 900 V, 1,000 V, or more.

[0176] "Power" is the rate per unit time at which electrical energy is transferred through an electric circuit. It is the rate at which work is done. In an electric circuit, power is measured in watts (W) and is a function of both voltage and current.

[0177] P=IE Where P = power in watts, I = current in amps and E = voltage in volts. Power generally generates heat, so "high power" is often used to refer to devices or applications that generate heat above 100°C.

[0178] As used herein, "high frequency" or "HF" refers to the range of radio frequency electromagnetic waves between 3 and 30 megahertz (MHz).

[0179] As used herein, "dielectric" refers to an insulating material that has the property of transmitting electric force without conduction. When a dielectric is placed in an electric field, charges do not flow through the material as they do in a conductor, but instead shift slightly from their average equilibrium position, causing dielectric polarization. Due to dielectric polarization, positive charges move in the direction of the electric field, and negative charges shift in the opposite direction to the field. This creates an internal electric field that reduces the overall electric field within the dielectric.

[0180] As used herein, the terms "dielectric constant," "relative permittivity," and the abbreviation "Dk" refer to the ratio of a material's dielectric constant (a measure of electrical resistance) to the permittivity of free space, which is given a value of 1. Simply put, the lower the Dk of a material, the better it functions as an insulator. As used herein, "low dielectric constant" refers to a material with a Dk lower than that of silicon dioxide, which has a Dk of 3.9. Thus, "low dielectric constant" means a Dk less than 3.9, typically less than about 3.5, and most often less than about 3.0. The most demanding, cutting-edge electronics applications may require "ultra-low dielectric constants" well below 3.0, such as less than about 2.7, less than about 2.6, or even less than about 2.5.

[0181] As used herein, the terms "dissipation dielectric factor," "dissipation dielectric constant," and the abbreviation "Df" are used herein to refer to a measure of the rate at which energy is lost in a thermodynamically open, dissipative system. Simply put, Df is a measure of how inefficient an insulating material in a capacitor is. It typically measures the heat lost when an insulator, such as a dielectric, is subjected to an AC electric field. The lower the Df of a material, the more efficient it is. A "low dissipation dielectric constant" typically refers to a Df of less than about 0.01 at 1 GHz frequencies, less than about 0.005 at 1 GHz frequencies, or equal to or less than 0.001 at 1 GHz frequencies.

[0182] "Low loss" and "ultra-low loss" PCBs are those that require dielectric materials with Df values ​​less than 0.0025. All printed circuit board (PCB) materials exhibit both conduction and dielectric losses.

[0183] "Low-loss" and "ultra-low-loss" PCBs minimize both of these types of losses and are typically only obtainable with dielectric materials with Df values ​​below 0.0025. Conduction losses are primarily resistive losses in the conductive layer and leakage of charge through the dielectric. Dielectric losses result from fluctuating electric fields generated by alternating currents, which cause the molecular structure of the material to move, generating heat. Dielectrics are materials that are poor conductors of electrical current. They are insulators because they have few free electrons available to carry current. However, when exposed to an electric field, polarization occurs, causing positive and negative charges to displace relative to the field. This polarization reduces the electric field in the dielectric, thereby losing some of the applied electric field. The effect of polarization or dipole moment in a dielectric is quantified as the "loss tangent," which describes the dielectric's inherent dissipation of an applied electric field. The loss tangent is derived from the tangent of the phase angle between the resistive and reactive components of the complex permittivity system. This property is dimensionless and is often referred to as the "loss factor," "dissipation factor," or "dielectric loss."

[0184] In electronics, "leakage" is the gradual transfer of electrical energy across a boundary normally considered an isolation, such as the spontaneous discharge of a charged capacitor, the magnetic coupling of a transformer with another component, or the flow of current across an off-state transistor or reverse-polarity diode. Another type of leakage can occur when current leaks from its intended circuit instead of flowing through some alternative path. This type of leakage is undesirable because the current flowing through the alternative path can cause damage, fire, RF noise, or electrocution.

[0185] As used herein, "leakage current" refers to the gradual loss of energy from a charged capacitor and is primarily caused by electronic devices connected to the capacitor, such as transistors and diodes. These devices draw small amounts of current even when turned off. "Leakage current" also refers to the current that flows when the ideal current is zero. This is true when an electronic assembly is in standby, disabled, or "sleep" mode (standby power). These devices may draw one or two microamps when quiescent, compared to hundreds or thousands of milliamps during full operation. These leakage currents are becoming a critical factor for portable device manufacturers because they have an undesirable impact on consumer battery runtime.

[0186] As used herein, "photoimageable" refers to the ability of a compound or composition to be selectively cured only in areas exposed to light. This causes the exposed areas of the compound or composition to harden and become insoluble, while the unexposed (e.g., masked) areas of the compound or composition remain uncured and are therefore soluble in the developer solvent in which the uncured compound or composition is soluble. Typically, this operation is performed using ultraviolet light as a light source and a photomask as a means to define where exposure occurs. Selective patterning of dielectric layers on silicon wafers can be performed according to various photolithography techniques known in the art. In one method, a photosensitive polymer film ("photoresist film") is coated on the desired substrate surface and dried. Next, a "photomask" (e.g., an opaque plate with holes or transparencies that allow light to shine through in a defined pattern; see, for example, Figure 7A) containing the desired patterning information is placed in close proximity to the photoresist film. The photoresist is irradiated through an overlying photomask with one of several types of imaging radiation, including UV light, electron beam electrons, X-rays, or ion beam. Exposure to radiation causes the polymer film to undergo a chemical change (crosslinking) and a concomitant change in solubility. After irradiation, the film-coated substrate is immersed in a developer solution, which selectively removes the uncrosslinked or unexposed areas of the film. "Photolithography" is the technical term used to describe the general process (or variations thereof) for forming selective patterns in an underlying substrate.

[0187] As used herein, "passivation" refers to the process of "passivating" a material with respect to another material or state. A "passivation layer" refers to a layer commonly used to encapsulate a semiconductor device, such as a semiconductor wafer, isolating the device from its immediate environment and thereby protecting the device from oxygen, water, and the like, as well as airborne or spaceborne contaminants, particles, humidity, or other contaminants that may affect the integrity of the underlying passivation layer. Passivation layers are typically formed from inert materials used to coat the device. This encapsulation process also provides passivation for semiconductor devices by terminating dangling bonds formed in the manufacturing process and by adjusting the surface charge by reducing or increasing the surface leakage current associated with these devices.

[0188] In certain embodiments of the present invention, a "passivation layer" (PL) comprises a dielectric material disposed over a microelectronic device. Such PL is typically patterned to form openings therein that provide electrical contact to the microelectronic device. Often, the passivation layer is the final dielectric disposed over the device and acts as a protective layer.

[0189] The terms "interlevel dielectric layer" and "ILD" refer to a layer of dielectric material disposed over a first pattern of conductive traces and insulating it from a second pattern of conductive traces that may be stacked on top of the first pattern. Such ILD layers are typically patterned or drilled to provide openings (called "vias," short for "vertical interconnect access" channels) that allow electrical contact between the first and second patterns of conductive traces in specific regions or layers of a multilayer printed circuit board. Other regions of such ILD layers are via-free to strategically prevent electrical contact between the conductive traces of the first and second patterns or layers in such other regions.

[0190] As used herein, "redistribution layer" or "RDL" refers to additional conductive elements (e.g., metal layers or metallization lines) added onto a chip that make the "I / O" (input / output) pads of an integrated circuit ("IC") available elsewhere. The extra conductive elements are insulated by layers of passivation material, as described below.

[0191] As used herein, "fan-out package" refers to an I / O circuit package in which a silicon chip is expanded by molding the chip in a dielectric material (e.g., epoxy resin) to expand the size of the chip. The I / O pads of the silicon chip can be made available in the fan-out region using RDLs.

[0192] As used herein, "B-stageable" refers to the property of an adhesive having a first solid phase, followed by a tacky, rubbery stage at elevated temperatures, followed by another solid phase at even elevated temperatures. The transition from the tacky, rubbery stage to the second solid phase is a thermoset. However, prior to the thermoset, the material behaves similarly to a thermoplastic material. Therefore, such adhesives allow for low lamination temperatures while offering high thermal stability.

[0193] As used herein, "die" or "semiconductor die" refers to a small block of semiconductor material upon which functional circuitry is fabricated.

[0194] A "flip-chip" semiconductor device is one in which the semiconductor die is mounted directly to a wiring substrate, such as a ceramic or organic printed circuit board. The conductive terminals of the semiconductor die are physically and electrically connected directly to the wiring pattern on the substrate, usually in the form of solder bumps, without the use of wire bonds or tape automated bonding (TAB). The die is mounted face-down, hence the term "flip-chip," since the conductive solder bumps that connect to the substrate are on the active surface of the die or chip.

[0195] As used herein, a "hard block" or "hard segment" refers to a block of a copolymer (typically a thermoplastic elastomer) that is hard at room temperature due to a high melting point (Tm) or high Tg. In contrast, a "soft block" or "soft segment" has a Tg below room temperature.

[0196] The present invention builds on Applicant's decades of research into polyimides for use in a myriad of applications in the electronics industry. At the same time, the industry has dramatically advanced the limits of performance and complexity of electronic devices. The increasing miniaturization of components and devices has emphasized the need for increasingly high-performance passivation polymers, formulations, and layers to insulate and protect densely packed features.

[0197] The present invention is also based on the recognition that the polyimides developed by the applicant possess many of the properties necessary to meet these growing demands, compared to industry-standard conventional polyimides synthesized via a polyamic acid intermediate. Specifically, the chain-propagated polyimide polymers of the present invention have a flexible aliphatic backbone instead of the aromatic ether backbone found in conventional polyimide polymers. Due to their imide linkages, the polyimide polymers described herein have the same heat resistance as conventional polyimides, but exhibit lower shrinkage, thereby reducing stress on wafers and silicon-based components compared to conventional polyimides. Thus, the polyimides of the present invention reduce the likelihood of delamination and warpage of semiconductor interconnect layers in applications where these defects have little tolerance for error. Passivation formulations of the present invention incorporating the high-performance chain-propagating polyimides described herein are less sensitive to stress than conventional polyimides and are therefore more suitable for use with very thin silicon wafers. Furthermore, the polyimides of the present invention absorb substantially less moisture than conventional polyimides used in coatings, thus providing better protection and less change in frequently encountered environmental conditions.

[0198] Advantageously, the uncured polyimides of the present invention are fully imidized and soluble in common organic solvents (e.g., aromatics and ketones) used in passivation applications such as redistribution layers. Furthermore, upon curing, the polyimide-containing formulations of the present invention are insoluble in common solvents such as cyclopentanone, cyclohexanone, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol dimethyl ether, alcohols, ethers, esters, ketones, and combinations thereof, and are therefore photolithographically developable. These and other properties make the polyimides of the present invention photoimageable, thereby enabling patterning of passivation and redistribution layers.

[0199] Thus, the present invention provides passivation formulations useful as protective and insulating coatings and for insulating conductive traces and lines on chips, printed circuit boards, multilayer wiring boards, packages, devices, etc. Exemplary layers include passivation layers, interlayer dielectric layers, and redistribution layers (RDLs), including fan-out RDLs.

[0200] The passivating formulations provided by the present invention comprise at least one curable functionalized polyimide having a structure according to Formula I.

[0201] [ka]

[0202] In the formula, R is a substituted or unsubstituted aliphatic group, aliphatic ring, alkenyl, aromatic group, or heteroaromatic group; Q is a substituted or unsubstituted aliphatic group, aliphatic ring, alkenyl, aromatic group, or heteroaromatic group; and n is an integer having a value from 1 to 100.

[0203] In some embodiments, n is 1-50, 1-25, 1-10, 1-9, 1-8, 1-7, 1-6, 1-5, 1-4, 1-3, 1-2 or at least 1.

[0204] In certain embodiments, the C36 moiety is included. At least one R or Q is tricyclodecyldimethyl, norbornyldimethyl, cyclohexanedimethyl; cyclohexyl, isophoronyl; methylenebis(cyclohexyl)dimethyl; or methylenebis(2-methylcyclohexyl)dimethyl.

[0205] Exemplary polyimides suitable for use in the formulations of the present invention include:

[0206] [ka]

[0207] [ka]

[0208] [ka]

[0209] [ka]

[0210] [ka]

[0211] [ka]

[0212] where each n and m is an integer having a value from 1-50.

[0213] Polyimides can be used independently as monomers in polymer compositions, such as passivation layer or redistribution layer formulations, or can be combined with other materials and reagents to prepare wafer redistribution layer compositions. In certain embodiments, polyimides are used as the sole photoimageable thermosetting monomer in the redistribution layer compositions of the present invention.

[0214] In other embodiments, the curable functionalized polyimides can be combined with other curable functionalized polyimides and other monomers, such as thermosetting monomers, reactive diluents, etc., to form a complete formulated redistribution layer composition.

[0215] In yet another embodiment of the present invention, two or more curable functionalized polyimides can be combined and used as the redistribution layer.

[0216] In certain embodiments of the present invention, the combination of two or more curable functionalized polyimides having Formula I imparts properties to the formulation not found in compositions containing only a single polyimide. For example, certain high molecular weight polyimides (e.g., >10,000 Daltons) could not be adequately UV cured under short, low temperature (e.g., room temperature) conditions.

[0217] Such formulations can be cured by including a brief oven cure of a few minutes at higher temperatures (<200°C), but this additional step may not be desirable in certain circumstances. Incorporating a lower molecular weight (e.g., <10,000 Daltons) significantly increased cure under these conditions (see Example 7 below).

[0218] Thus, in certain embodiments, the present invention provides passivation formulations comprising a mixture of two or more curable functionalized polyimides; for example, a mixture of a first polyimide of low molecular weight (e.g., <10,000 Da), such as compounds 1 and 2, and a second polyimide of high molecular weight (e.g., =>10,000 Da), such as compounds 3-6.

[0219] The low molecular weight first polyimide can have an average molecular weight of less than about 10,000 Da, for example, about 9,500 Da to about 1,500 Da, about 8,500 Da to about 2,500 Da, about 7,500 Da to about 2,000 Da, or can be about 9,000 Da, about 8,000 Da, about 7,000 Da, about 6,000 Da, about 5,000 Da, about 4,000 Da, about 3,000 Da, about 2,000 Da, or about 1,000 Da.

[0220] The high molecular weight second polyimide generally can have a molecular weight greater than 10,000 Da, greater than 15,000 Da, greater than 20,000 Da, greater than 25,000 Da, greater than 30,000 Da, greater than 40,000 Da, or greater than 50,000 Da, for example, from about 11,000 Da to 100,000 Da, from about 15,000 Da to 75,000 Da, or from about 17,000 Da to 60,000 Da.

[0221] The first curable functionalized flexible polyimide is generally flexible and has a CTE of at least about 100 ppm / °C, at least about 150 ppm / °C, or at least about 200 ppm / °C.

[0222] The second curable functionalized polyimide has much less flexibility and a CTE of less than about 100 ppm / °C, less than about 70 ppm / °C, less than about 50 ppm / °C, or less than about 40 ppm / °C. In certain embodiments, the second curable functionalized polyimide has a CTE of about 40 ppm / °C to about 80 ppm / °C, or about 45 ppm / °C to about 75 ppm / °C. In certain embodiments, the second curable functionalized polyimide can have a Tg of at least about 100°C, at least about 120°C, at least about 130°C, at least about 140°C, or at least about 150°C.

[0223] The passivation formulation of claim 16, wherein the at least one second curable functionalized polyimide has a Tg between about 100°C and about 150°C.

[0224] The curable functionalized polyimide is generally the major component by weight in the passivation formulations provided herein. The total amount of the curable functionalized polyimide in the formulation is about 50% to about 98% by weight, based on the total weight of the composition minus the solvent. In certain embodiments of the present invention, the curable functionalized polyimide is present in the composition, such as a redistribution layer composition, in an amount of about 60% to about 90% by weight, often about 65% to about 80% by weight, and more often about 70% to about 80% by weight, based on the weight of the composition excluding any solvent present.

[0225] The at least one first curable functionalized flexible polyimide can be about 15% to about 80% by weight of the formulation, for example, about 15%, about 25%, about 35%, about 45%, about 55%, about 65%, or about 75% by weight. In certain embodiments, the first polyimide comprises about 15% to about 25% by weight of the formulation.

[0226] The at least one second curable functionalized polyimide generally comprises about 45% to about 75% by weight, e.g., about 45%, about 40%, about 50%, about 55%, about 60%, about 65%, about 70%, or about 75% by weight.

[0227] The at least one first curable functionalized flexible polyimide can be, for example, Compound 1, Compound 2, and combinations thereof. The at least one second curable functionalized polyimide can be Compound 3, Compound 4, Compound 5, Compound 6, and mixtures thereof.

[0228] Passivating formulation The present invention provides a passivation formulation comprising: a) at least one curable functionalized polyimide compound or mixture of compounds described herein; and b) one reactive diluent and / or co-curing compound; or c) at least one adhesion promoter; or d) at least one coupling agent; or e) at least one UV initiator; or f) at least one solvent, or g) Any combination thereof.

[0229] In another embodiment, the passivation formulation of the present invention includes: a) at least one curable functionalized polyimide compound or mixture of compounds as described herein; b) at least one reactive diluent, co-curing compound, or combination thereof; c) at least one coupling agent, adhesion promoter, or combination thereof; and d) at least one curing initiator.

[0230] Curable functionalized polyimide compound mixtures In certain embodiments, the passivation formulation comprises a combination of Compound 1 and / or Compound 2 and one or more of Compound 3, Compound 4, Compound 5, and Compound 6. For example, the passivation formulation comprises a mixture of Compound 1 and Compound 4, or a mixture of Compound 1 and Compound 5.

[0231] In yet other embodiments, the passivation formulation comprises a mixture of any of Compound 3, Compound 4, Compound 5, and / or Compound 6 with an effective amount of Compound 1 and / or Compound 2 to cure the formulation upon UV irradiation.

[0232] Reactive Diluents and Co-Reactants Curable polyimides may require the addition of thermally stable co-reactants or reactive diluents to achieve complete UV cure. These additional compounds include, but are not limited to, liquid C36 bismaleimide of dimer diamine, divinyl ether of dimer diamine, diacrylate of dimer diamine, acrylic and vinyl ether resins.

[0233] In certain embodiments, the passivating formulation includes at least one "co-reactant," which is a monomer, oligomer, or polymer that can be co-cured with the curable functionalized polyimide compound.

[0234] Co-reactants include, for example, epoxies (e.g., epoxies based on glycidyl ethers of alcohols), phenols, bisphenols, oligomeric phenols, phenol novolacs, cresol novolacs, acrylates, methacrylates, maleimides, polyphenolic compounds (e.g., poly(4-hydroxystyrene)), anhydrides, dianhydrides, polyanhydrides such as styrene-maleic anhydride copolymers, imides, carboxylic acids, dithiols, polythiols, phenol-functional monomaleimides, bismaleimides, polymaleimides, monoitaconates, monomaleates, mono-fumarates, acrylic acids, methacrylic acids, cyanate esters, vinyl ethers, vinyl esters, or phenol-functional esters, ureas, amides, polyolefins (e.g., amine-, carboxylic acid-, hydroxy-, and epoxy-functional), siloxanes (e.g., epoxy-, phenolic-, carboxylic acid-, or thiol-functional), cyanoacrylates, allyl-functional compounds, and styrenics, and combinations thereof.

[0235] Comonomer coreactants suitable for use in polyimide-containing compositions include, but are not limited to, acrylates, methacrylates, acrylamides, methacrylamides, maleimides, vinyl ethers, vinyl esters, styrenic compounds, allyl-functional compounds, epoxies, curable epoxies, and olefins.

[0236] A "reactive diluent" according to the present invention is a material that reduces viscosity during processing and becomes part of the cured passivation layer after curing by copolymerization.

[0237] As used herein, "diluents" are added to formulations to modify their rheology, thereby reducing their viscosity, and can also soften and solvate reactants in film formulations, thereby facilitating interaction between the components in the formulation and thereby facilitating curing.

[0238] Curable polyimides may require the addition of thermally stable co-reactants or reactive diluents to fully UV cure. These additional compounds include dimer diamine liquid C 36 These include, but are not limited to, bismaleimides, divinyl ethers of dimer diamine, diacrylates of dimer diamine, acrylic and vinyl ether resins.

[0239] The following acrylates are non-limiting examples of suitable reactive diluents for use in the practice of this invention.

[0240] [ka]

[0241] [ka]

[0242] [ka]

[0243] The co-reactants and reactive diluents are typically present in amounts of 10% to about 40% by weight. In such embodiments, the composition will typically include co-curing compounds and / or reactive diluents in an amount equal to at least about 10%, at least about 20%, at least about 30%, or at least about 40% by weight of the formulation.

[0244] Coupling Agents and Adhesion Promoters As used herein, the term "coupling agent" refers to a chemical species that can bond dissimilar materials, such as inorganic and organic materials, and is particularly useful for bonding to mineral surfaces. Coupling agents are often bifunctional molecules, with one functional group reacting with the mineral surface and the other functional group reacting with the polymer, bonding the two together. Thus, the coupling agent facilitates bonding of the passivation layer to the substrate to which it is applied.

[0245] Coupling agents are typically silanes, titanates, or zirconates that form covalent bonds with the substrate. For example, Si-OH groups on the surface of a silicon wafer react with silane coupling agents to form Si-O-Si covalent bonds, typically at temperatures above 100°C.

[0246] Exemplary coupling agents contemplated for use in the practice of the present invention include silicate esters, metal acrylate salts (e.g., aluminum methacrylate), titanates (e.g., titanium methacryloxyethylacetoacetate triisopropoxide), zirconates, or compounds containing copolymerizable groups and chelating ligands (e.g., phosphines, mercaptans, acetoacetates, etc.). In some embodiments, the coupling agent contains both a copolymerizable group (e.g., vinyl, acrylate, methacrylate, epoxy, thiol, anhydride, isocyanate, and phenolic moiety) and a silicate ester group. The silicate ester group of the coupling agent can condense with metal hydroxides present on the mineral surface of the substrate, while the copolymerizable group can copolymerize with other reactive components of the wafer passivation composition of the present invention. In certain embodiments, the coupling agent contemplated for use in the practice of the present invention is an oligomeric silicate coupling agent, such as poly(methoxyvinylsiloxane). Coupling agents that may be used in the practice of the present invention also include the epoxy-based coupling agent, 2-(3,4 epoxycyclohexyl)ethyltrimethoxysilane, and the amine-based coupling agent, N-phenyl-3-aminopropyltrimethoxysilane, both of which are considered adhesion promoters at the same time.

[0247] In yet another embodiment of the present invention, the addition of amino-functionalized silanes is contemplated for use in the practice of the present invention. Without wishing to be bound by any theory, amino-functionalized coupling agents have been shown to adhere to the copper surface and prevent the migration of copper oxide to the resin, a major concern in delamination that occurs without surface treatment.

[0248] Amino-functionalized coupling agents contemplated for use in the practice of the present invention include, but are not limited to, 3-aminopropyltrimethoxysilane; 3-aminopropyltriethoxysilane; N-phenyl-3-aminopropyltrimethoxysilane; N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane; N-2-(aminoethyl)-3-aminopropyltrimethoxysilane.

[0249] In yet another embodiment of the present invention, two or more coupling agents may be used in combination to achieve ultimate adhesion to the copper surface.

[0250] An "adhesion promoter" is a bifunctional material that enhances the adhesive strength between a coating and a substrate. Adhesion promoters enhance adhesion by incorporating functional additives that can chemically bond to compounds in the formulation and / or the substrate. These include bifunctional surfactants and other molecules with short organic chains used at low concentrations.

[0251] Adhesion promoters are similar to coupling agents, but generally do not form covalent bonds to the substrate or polymer formulation, however, they have an affinity for both the substrate and the polymer formulation, which can be ionic interactions and other non-covalent types of bonding.

[0252] Adhesion promoters are particularly useful for bonding to copper-plated silicon wafers, such as in RDL applications. Certain adhesion promoters have an affinity for both silicon and copper. Adhesion promoters contemplated for use in these situations include carboxylic acids, anhydrides, and amines. Specific examples include polybutadiene grafted with maleic anhydride groups and 4-META (4-methacryloyloxyethyl trimellitate anhydride). Combinations of adhesion promoters can also be used to enhance adhesion to copper. 3-(triethoxysilyl)propyl-succinic anhydride is useful in combination to improve adhesion to copper surfaces, especially under hot and humid conditions.

[0253] In RDL applications, copper oxide on the surface of the wafer has been observed to migrate from the copper-plated surface into the resin matrix of the applied coating (e.g., passivation or RDL), thereby causing delamination. The combination of a coupling agent (especially N-phenyl-3-aminopropyltrimethoxysilane) helps to keep the copper oxide in place, promoting better surface adhesion in RDL applications.

[0254] Certain other adhesion promoters can be added to the formulation to aid adhesion to silicon and / or copper; non-limiting examples of suitable adhesion promoters include, but are not limited to, maleate RICON® (maleate polybutadiene), maleimide-carboxylic acid, and 4-META (shown below).

[0255] [ka]

[0256] solvent In certain embodiments, solvents may be used in the practice of the present invention. For example, when spin-coating a passivation formulation for RDL applications onto a circular wafer, it is desirable to achieve a uniform coating across the entire wafer. That is, the solvent or solvent system must be capable of delivering the same amount of material to every point on the wafer, from the center to the edge of the wafer. Ideally, the redistribution layer compound solution is "Newtonian," with a thixotropic slope of 1.0. In certain embodiments, the solution used to dispense the redistribution layer compound has a slope ranging from 1.0 to about 1.2.

[0257] In some embodiments, the solvent or solvent system has a boiling point ranging from about 100° C. to about 220° C. In certain embodiments, the solvent is anisole.

[0258] Polyimides can be used independently as monomers in polymer compositions, such as redistribution layer compositions, or can be combined with other materials and reagents to prepare wafer redistribution layer compositions. Polyimides can be used as the sole photoimageable thermosetting resin / monomer in the redistribution layer compositions of the present invention.

[0259] In other embodiments, the curable functionalized polyimide can be combined with other monomers, such as thermosetting monomers, reactive diluents, etc. to create a complete redistribution layer composition formulation.

[0260] In yet another embodiment of the present invention, two or more curable functionalized polyimides can be combined and used as the redistribution layer.

[0261] Synthesis of photoimageable polyimides. The fundamental difference between the passivation formulations of the present invention (containing at least one curable functionalized polyimide compound of Formula I) and formulations containing conventional polyimides is the method by which they are synthesized. As noted above, conventional polyimides used in passivation layers are synthesized in situ from a polyamic acid solution, then UV-cured, followed by a high-temperature cure at temperatures above 200°C. Several hours of such a "hard bake" cure are a prerequisite for ring closure and complete imidization. If complete imidization and ring closure are not achieved due to insufficient hard bake time or temperature, or because of limited reaction progress when the reactants are passivated on the substrate, residual polyamic acid and incomplete reaction products can impart undesirable properties to the "polyimide" product and subsequent reaction steps.

[0262] The general process for synthesizing conventional polyimides is summarized below in Scheme 1. Although polyimides are synthesized with sufficient hard-bake curing, it is not uncommon to find incomplete ring closure, as shown in Scheme 1.

[0263] Furthermore, the linkages in conventional polyimides are inherently less stable than the equivalent linkages in polyimides according to the present invention, which are produced by the condensation reaction of diamines with dianhydrides, as shown in Scheme 2 below. Scheme 2 illustrates the synthesis and functionalization of polyimides according to the present invention. This Scheme 2 shows the production of an amine-terminated polyimide followed by reaction with maleic anhydride to produce a bismaleimide. Those skilled in the art will appreciate that appropriate selection of the starting amine and dianhydride can produce polyimides with a wide range of terminal and pendant reactive functional groups, while varying the ratio of diamine to anhydride can produce compounds with a wide range of molecular weights. By definition, the reactive terminal and pendant functional groups can subsequently react to produce a virtually infinite variety of cure sites.

[0264] [ka]

[0265] [ka]

[0266] Thus, the present invention provides passivating formulations comprising at least one curable functionalized polyimide compound synthesized by condensation of a diamine with an anhydride or dianhydride, followed by terminal and / or pendant functionalization. The examples describe condensation reactions resulting in an amine-terminated polyimide (Example 1) and an anhydride-terminated polyimide (Examples 2-6), while both polyimides can be converted to maleimides. The present invention contemplates functionalization with other reactive groups.

[0267] A wide variety of diamines are contemplated for use in the practice of the present invention. Examples of diamines suitable for preparing at least one curable functionalized polyimide compound include, but are not limited to, the following: dimer diamines; TCD-diamines; 1,10-diaminodecane; 1,12-diaminodecane; 1,2-diamino-2-methylpropane; 1,2-diaminocyclohexane; 1,2-diaminopropane; 1,3-diaminopropane; 1,4-diaminobutane; 1,5-diaminopentane; 1,6-diaminohexane; 1,7-diaminoheptane; 1,8-diaminooctane; 1,9-diamino Minononane;3,3'-Diamino-N-methyldipropylamine;Diaminomaleonitrile;1,3-Diaminopentane;9,10-Diaminophenanthrene;4,4'-Diaminooctafluorobiphenyl;3,5-Diaminobenzoic acid;3,7-Diamino-2-methoxyfluorene;4,4'-Diaminobenzophenone;3,4-Diaminobenzophenone;3,4-Diaminotoluene;2,6-Diaminoanthroquinone;2,6-Diaminotoluene;2,3-Diaminotoluene;1,8-Diaminonaphthalene;2,4-Cumene Benzenediamine;1,3-bisaminomethylbenzene;1,3-bisaminomethylcyclohexane;2-chloro-1,4-diaminobenzene;1,4-diamino-2,5-dichlorobenzene;1,4-diamino-2,5-dimethylbenzene;4,4'-diamino-2,2'-bistrifluoromethylbisphenyl;Bis(amino-3-chlorophenyl)ethane;Bis(4-amino-3,5-dimethylphenyl)methane;Bis(4-amino-3,5-diethylphenyl)methane;Bis(4-amino-3-ethylphenyl)methane;Bis(4-amino-3-ethylphenyl)methane Bis(4-amino-3-ethyl)diaminofluorene;Diaminobenzoic acid;2,3-Diaminonaphthalene;2,3-Diaminophenol;Bis(4-amino-3-methylphenyl)methane;Bis(4-amino-3-ethylphenyl)methane;4,4'-Diaminophenyl sulfone;4,4'-Oxydianiline;4,4'-Diaminodiphenyl sulfide;3,4'-Oxydianiline;2,2-Bis[4-(3-aminophenoxy)phenyl]propane;2,2'-Bis[4-(4-aminophenoxy)phenyl]propane;1,3-Bis(4-aminophenoxy)benzene;4,4'-Bis(aminophenoxy)bisphenyl;4,4'-Diamino-3,3'-dihydroxybiphenyl;4,4'-Diamino-3,3'-dimethylbiphenyl;4,4'-Diamino-3,3'-dimethyloxybiphenyl;Visaniline M;Visaniline P;9,9-Bis(4-aminophenyl)fluorine;o-Toluidine sulfone;Methylenebis(anthraniline) Acid;1,3-Bis(4-aminophenoxy)-2,2-dimethylpropane;1,3-Bis(4-aminophenoxy)propane;1,4-Bis(aminophenoxy)butane;1,5-Bis(4-aminophenoxy)butane;2,3,5'-Tetramethylbenzidine;4,4'-Diaminobenzanilide;2,2-Bis(4-aminophenyl)hexafluoropropane;Polyalkylenediamines (e.g., Huntsman's Jeffamine D-230, D-400, D2000, and D-4000 products; 1,3-cyclohexanebis(methylamine); m-xylylenediamine; p-xylylenediamine; bis(4-amino-3-methylcyclohexyl)methane; 1,2-bis(2-aminoethoxy)ethane; 3(4),8(9)-bis(aminomethyl)tricyclo(5.2.1.0)decane; 1,3-diamino-2-propanol; 3-amino-1,2-propanediol; ethanolamine; and 3-amino-1-propanol.

[0268] In certain embodiments of the present invention, the diamine is selected from the group consisting of dimeric diamines, TCD-diamines, and combinations thereof.

[0269] A wide variety of anhydrides are contemplated for use in synthesizing at least one curable functionalized polyimide compound, including, but not limited to, biphenyltetracarboxylic dianhydride; pyromellitic dianhydride; polybutadiene-grafted-maleic anhydride; polyethylene-grafted-maleic anhydride; polyethylene-alt-maleic anhydride; polymaleic anhydride-alt-1-octadecene; polypropylene-grafted-maleic anhydride; poly(styrene-co-maleic anhydride); 1,2,3,4-cyclobutanetetracarboxylic dianhydride; 1,4,5,8-naphthalenetetracarboxylic dianhydride; 3,4,9,10-perylenetetracarboxylic dianhydride. bicyclo(2.2.2)oct-7-ene-2,3,5,6-tetracarboxylic dianhydride; diethylenetriaminepentaacetic dianhydride; ethylenediaminetetraacetic dianhydride; 3,3',4,4'-benzophenonetetracarboxylic dianhydride; 3,3',4,4'-biphenyltetracarboxylic dianhydride; 4,4'-oxydiphthalic dianhydride; 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride; 2,2'-bis(3,3-dicarboxyphenyl)hexafluoropropane dianhydride; 4,4'-bisphenol A diphthalic dianhydride; 5-(2,5-dioxytetrahydro)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride; and combinations thereof.

[0270] In certain embodiments of the present invention, the anhydride is selected from the group consisting of biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, and combinations thereof.

[0271] Passivated Polyimide Compounds The present invention provides a passivation formulation suitable for spin-coating onto a wafer containing multiple microelectronic devices, comprising at least one fully imidized, functionalized polyimide polymer, the photoimageable polyimide of Formula I above.

[0272] Individual photoimageable polyimides of Formula I can be used independently as the primary monomer in a passivation formulation or can be combined with other photoimageable polyimides of Formula I, other materials and reagents to prepare passivation formulations.

[0273] Advantageously, cured aliquots of the passivation formulations described herein have a Tg of at least about 90° C., at least about 100° C., at least about 110° C., or at least about 120° C., and a percent elongation of at least about 40%, at least about 45%, at least about 50%, or at least about 55%. In certain embodiments, cured aliquots of the passivation formulations have a Tg of at least about 100° C. and a percent elongation of at least about 40%.

[0274] The passivation formulations are suitable for use in any application requiring insulation between elements or features, particularly conductive metallization such as lines, traces, and contact pads. Accordingly, the present invention provides passivation formulations suitable for use as passivation layers, RDLs, and IDLs, and methods for their use. Also provided are passivated chips, devices, packages, etc., or any portion thereof, having a cured layer of the passivation formulation described herein. Figure 1 is a schematic flow diagram illustrating a general process for passivating an electronic component, such as a chip, device, or package. The top diagram shows a chip 1 bonded to a substrate 2 (such as a printed circuit board). The first step (Step A in Figure 1) is to apply a layer of a passivation formulation according to the present invention to the component or portion thereof. The center diagram in Figure 1 shows the formulation being poured from a beaker 4 onto the chip. The chip is intended to generally represent application in all configurations. Those skilled in the art will appreciate that various methods can be used to apply the formulation, including, but not limited to, painting, brushing, spraying, doctor blading, dipping, spin coating, and molding and pouring, are encompassed by the present invention. The formulation can be applied to the entire surface of the component, including the top, bottom, and all sides, or it can be applied to only a portion of the component. FIG. 1 shows that formulation 3 is applied to chip 1 while it is attached to substrate 2, thereby applying only to the top and side portions of the chip. In this representation, the formulation flows over chip 1 and onto adjacent portions of substrate 2. In other embodiments of the present invention, the entire surface of the component (e.g., chip 1) is covered. Excess formulation 3 can then be removed by any method known in the art. For example, excess formulation can be scraped off the substrate. In other embodiments, removal can be performed by photolithography to remove excess formulation from unwanted portions of chip 1, such as portions covering contact points or vias.

[0275] 1 (Step B) illustrates the use of UV radiation to cure the formulation applied to chip 1 to form passivated chip 5. After curing (e.g., UV curing), the polyimide-containing passivation formulation of the present invention is developable with common solvents such as cyclopentanone and cyclohexanone.

[0276] A cross-section of a passivated chip 5 is shown in FIG. 2, having a hardened layer of passivation compound over the underlying chip 1.

[0277] redistribution layer A redistribution layer is a type of passivation metallization structure that provides a way to form bond pads at one location on a chip that are available elsewhere on the chip or beyond (e.g., in the case of fan-out packages, as described below). Using RDLs, bond pads (metallized pads for connecting wires, traces, metallization lines, etc.) can be functionally eliminated around the face of the die (e.g., in flip-chip applications) and solder balls can be isolated at closely spaced or densely packed sites, thereby distributing attachment stresses. In stacked-die packages, RDL layers allow unique placement of address lines using the same generic chip. Furthermore, bond pads can be moved to more convenient locations based on the overall geometry of the chip and the surrounding package and connections.

[0278] RDL formulation. The formulation developed for the passivation layer is used with minor modifications.

[0279] Generally, the redistribution layer compositions of the present invention can be photoimaged under UV light exposure at or near room temperature. All undeveloped portions of the film can then be removed by immersion in an appropriate solvent or solvent combination or by jet spray application. The remaining photocured polyimide film can then be fully cured by post-baking at 125-175°C for approximately 15 minutes to 1 hour.

[0280] Free radical curing inhibitors may also be added to the compositions described herein to extend their useful shelf life. Examples of free radical inhibitors include hindered phenols such as 2,6-di-tert-butyl-4-methylphenol; 2,6-di-tert-butyl-4-methoxyphenol; tert-butylhydroquinone; tetrakis(methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate))benzene; 2,2'-methylenebis(6-tert-butyl-p-cresol); and 1,3,5-trimethyl-2,4,6-tris(3',5'-di-tert-butyl-4-hydroxybenzyl)benzene. Hydrogen donating antioxidants, such as derivatives of p-phenylenediamine and diphenylamine, are also useful. It is also well known in the art that hydrogen donating antioxidants can be synergistically combined with quinones and metal deactivators to create highly effective inhibitor packages. Examples of suitable quinones include benzoquinone, 2-tert-butyl-1,4-benzoquinone, 2-phenyl-1,4-benzoquinone, naphthoquinone, and 2,5-dichloro-1,4-benzoquinone. Examples of metal deactivators include N,N'-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazine, oxalyl bis(benzylidenehydrazide), and N-phenyl-N'-(4-toluenesulfonyl)-p-phenylenediamine.

[0281] Nitroxyl radical compounds such as TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy, free radical) are also effective as inhibitors at low concentrations. The total amount of antioxidant and synergist is typically in the range of 100-2000 ppm based on the total weight of the base resin. Other additives, such as adhesion promoters, of types and amounts known in the art, can also be added.

[0282] RDL Process. Figures 3 and 4A-2E (cross-section views) illustrate the process used to create RDLs. A simplified chip 110 is shown with one bond pad 200 (also called an "I / O pad"). The chip 110 is formed from wafer material 10 (e.g., silicon) with conductive regions of metallization 202 and a passivation layer 206 that partially covers the metallization except for a contact region 204. The black dashed rectangle in Figure 3 indicates the extent of the metallization 202 below the surface of the passivation layer 206, with only a portion (of the contact region 204) exposed at the surface of the chip 110. Pad rewiring involves establishing a conductive connection between an existing bond pad 200 and a new bond pad 226 with a line of surface metallization 220 between two points.

[0283] The redistribution lines 220 can be fabricated directly on the primary passivation 206 (not shown) or routed onto a new layer of polymer passivation material 210 to ensure proper protection of the metallization on all sides, as shown in FIGS. 3 and 4B. In these figures, the surface of the chip 110 is coated with a first passivation layer 206 (Step A), except for the contacts 204 of the existing original I / O pads 200. In other embodiments, this first polymer layer can be placed only in areas that will receive the metallization. In either case, the polymer passivation layer can be applied selectively to the surface of the chip or to the entire surface (e.g., by spin coating), and photolithography can be used to remove excess polymer that extends beyond the desired areas.

[0284] Metallization (e.g., copper foil, electroplating) is then applied to the new pad 226 using methods known in the art at the contacts 204 (shown by the white dashed lines), the surrounding area, and along the continuous line 220, thereby conductively connecting the original pad 200 to the new pad 226 (FIG. 3, step B and FIG. 4C).

[0285] 3, a second redistribution layer 212 is formed over the metallization 220, completely covering the existing original pads 200 and exposing only the contacts 222 of the new pads 226. In this figure, the second redistribution layer 212 is shown limited to the metallization paths. However, the second redistribution layer 212 can cover the entire chip surface as long as it does not interfere with other functions of the chip.

[0286] Finally (Step D), solder bumps 230 can be placed on the new rewired pads 226 for wire bonding or other connections.

[0287] Advantageously, the polyimides of the present invention are photoimageable, thereby enabling patterning of redistribution layers. For example, the passivating redistribution formulations of the present invention can be applied to the surface of an IC chip and / or fan-out package, then photoimaged to remove areas designated for via holes or UBM (under bump metallization) sites, followed by sputtering and plating the metallization to contact the underlying metallization layer and facilitate high density connections.

[0288] Fan-out RDL Redistribution layers have traditionally been used on the surface of individual chips. However, the new technology of "fan-out" wafer-level packaging (FOWLP) has significantly expanded the need for, and consequently the use of, RDLs. FOWLP (distinguished from "fan-in" WLP, in which packaging is performed at the wafer level before dicing, thereby producing a die-sized package rather than a larger-than-die size) expands the surface area of ​​an IC chip by embedding singulated chips in a molded package produced after singulation. Multiple chips can be molded into the same package, and the original I / O pads can be rerouted to the fan-out region of the package. Redistribution layers make relatively inexpensive, low-CTE polymers (e.g., epoxies) suitable for molding delicate metallization lines from the silicon chip to the fan-out region, thereby allowing I / O pads to be rerouted over a substantially increased surface area.

[0289] FIG. 5 is a top perspective view of the fan-out package, and FIG. 6 is a cross-sectional view through the center of the package on plane VI. For clarity, only some of the repeated structures 200 (original I / O pads), 220 (redistribution metallization lines), and 230 (solder balls) are numbered in the drawing. The original chip 110 (the central gray box) is placed in the center of the package 250 and surrounded by a molded polymer composition 240, forming a “fan-out” region 260. The dense original I / O pads 200 on the chip 110 are rerouted around the periphery of the “fan-out” region 260 using the process illustrated for a single rerouting pad in FIGS. 5 and 4A-E: a first layer 210 of passivating rerouting material is applied, and then a conductive metallization line 220 is provided from the original pad 200 to a new pad 226 (obscured by the solder ball in FIG. 5; see FIG. 6), which is then covered with a second passivation layer 212. Layers 210, 220, and 212 together form a general redistribution layer 214. The dark black line represents a metallization line 220 that follows the path from original pad 200 to redistributed pad 226, upon which a solder ball 230 is placed.

[0290] Another desirable feature of the passivation formulations of the present invention is that, once cured, they have much lower moisture absorption than conventional polyimide passivation formulations. Therefore, there is little risk that the RDL formulations will expose sensitive metallization to corrosive conditions.

[0291] The following non-limiting acrylates are suitable reactive diluents for use in the practice of the present invention:

[0292] [ka]

[0293] [ka]

[0294] [ka]

[0295] Curing initiator The present invention provides passivating formulations comprising at least one compound of Formula I and at least one curing initiator. The curing initiator is typically present in the passivating formulations of the present invention in an amount of 0.1% to about 5% by weight, based on the total weight of the formulation. In some embodiments, the curing initiator is present in an amount of at least about 0.5% by weight, often at least about 1% by weight, often at least about 2% by weight, and in some embodiments at least about 3% by weight, based on the total weight of the composition.

[0296] Free Radical Initiators. In certain embodiments of the present invention, the curing initiator comprises a free radical initiator. Free radical initiators contemplated for use in the practice of the present invention typically decompose at temperatures ranging from about 70° C. to 180° C. (i.e., have a half-life ranging from about 10 hours). Exemplary free radical initiators contemplated for use in the practice of the present invention include peroxides (e.g., dicumyl peroxide, dibenzoyl peroxide, 2-butanone peroxide, tert-butyl peroxybenzoate, di-tert-butyl peroxide, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, bis(tert-butylperoxyisopropyl)benzene, and tert-butyl hydroperoxide), azo compounds (e.g., 2,2′-azobis(2-methylpropanenitrile), 2,2′-azobis(2-methylbutanenitrile), and 1,1′-azobis(cyclohexanecarbonitrile)). Other free radical initiators known in the art may also be suitable for use in the compositions of the present invention.

[0297] Photoinitiators. Free radical initiators also include photoinitiators. In the case of formulations of the present invention that include a photoinitiator, the curing process can be initiated, for example, by UV radiation. In one embodiment of the present invention, the photoinitiator is present in a concentration of 0.1% to 10% by weight, based on the total weight of the composition (excluding any solvent).

[0298] In one embodiment, the photoinitiator comprises 0.5 to 3.0 wt. % based on the total weight of the organic compounds in the composition. In other embodiments, the photoinitiator is present at least about 0.5 wt. %, often at least about 1 wt. %, often at least about 2 wt. %, and in some embodiments at least about 3 wt. %, based on the total weight of the organic compounds in the composition.

[0299] Photoinitiators include benzoin derivatives, benzil ketals, α,α-dialkoxyacetophenones, α-hydroxyalkylphenones, α-aminoalkylphenones, acylphosphine oxides, titanocene compounds, combinations of benzophenone with amines or Michler's ketone, and similar photoinitiators recognized by those skilled in the art.

[0300] In some embodiments, both photoinitiation and thermal initiation may be desirable. For example, the curing of an adhesive containing a photoinitiator can be initiated by UV irradiation, and in a later processing step, the curing can be completed by applying heat to achieve free radical curing. Therefore, both UV and thermal initiators can be added to the adhesive composition of the present invention.

[0301] In some embodiments, both photoinitiation and thermal initiation may be desirable. For example, the curing of a passivation formulation containing a photoinitiator can be initiated by UV irradiation, and in a subsequent processing step, the curing can be completed by applying heat to achieve free radical curing. Therefore, both UV and thermal initiators can be added to the adhesive composition of the present invention.

[0302] In yet another embodiment of the present invention, the addition of amino-functionalized silanes is contemplated for use in the practice of the present invention. Without wishing to be bound by any theory, amino-functionalized coupling agents have been shown to adhere to the copper surface and prevent the migration of copper oxide to the resin, a major concern due to delamination that occurs without surface treatment.

[0303] Amino-functionalized coupling agents contemplated for use in the practice of the present invention include, but are not limited to, the following compounds: 3-aminopropyltrimethoxysilane; 3-aminopropyltriethoxysilane; N-phenyl-3-aminopropyltrimethoxysilane; N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane; N-2-(aminoethyl)-3-aminopropyltrimethoxysilane; and the like.

[0304] In yet another embodiment of the present invention, two or more coupling agents may be used in combination to obtain complete adhesion to the copper surface.

[0305] Additional Co-Cure Compound. In certain embodiments, compositions, such as adhesive compositions, of the present invention include at least one additional compound capable of co-curing with the compound of Formula I. The additional compound is typically present in the adhesive composition in an amount of from about 10% to about 90% by weight, based on the total weight of the composition. In such embodiments, the composition will typically include an amount of co-curing compound equal to at least about 20% by weight, often at least about 30% by weight, often at least about 40% by weight, and in some embodiments at least about 50% by weight, based on the total weight of the composition.

[0306] assembly According to an embodiment of the present invention, a device includes a semiconductor wafer or other substrate and a redistribution layer disposed on a surface of the wafer or substrate, the redistribution layer being composed of a pre-imidized or partially imidized backbone having photopolymerizable functional groups according to the following structure:

[0307] [ka]

[0308] In the formula, R is a substituted or unsubstituted aliphatic group, alicyclic group, alkenyl group, aromatic group, or heteroaromatic group; Q is a substituted or unsubstituted aliphatic group, alicyclic group, alkenyl group, aromatic group, or heteroaromatic group; and n is an integer having a value from 1 to 100.

[0309] In another embodiment of the present invention, a passivated, photoimageable polyimide formulation is applied and after a photolithography step, a pattern is developed, followed by an excess removal or development stage. The excess polyimide can be developed using organic solvents such as cyclopentanone, cyclohexanone, PGMEA, propylene glycol dimethyl ether, and combinations thereof with other common solvents such as alcohols, esters, and ketones.

[0310] The present invention also provides electronic components having a cured layer of the passivation formulation described herein on at least a portion of the component, such as, for example, passivated chips, passivated devices, and packages, passivated semiconductor wafers, passivated wafer-level packages, passivated positive temperature coefficient (PTC) protective layers, passivated fan-out rewiring chips, and passivated circuit boards. In yet another embodiment of the present invention, the compounds of the present invention are used in patterning and etching several substrates, including, but not limited to, printed circuit boards, specialized photonics materials, microelectromechanical systems (MEMS), glass, and other micropatterning tasks.

[0311] The present invention will now be further described with reference to the following illustrative, non-limiting examples. Synthesis Example Example 1: Synthesis of Compound 1

[0312] [ka]

[0313] A 1-L reactor was charged with 164.7 g (300 mmol) of PRIAMINE™ 1075, followed by 300 g of NMP, 300 g of toluene, and 30 g of methanesulfonic acid. The solution was stirred, followed by the addition of 52.3 g (240 mmol) of pyromellitic dianhydride. The mixture was stirred and heated to 115°C for 2 hours, completing the azeotropic removal of approximately 9 mL of water to complete the amine-terminated polyimide synthesis. To the room-temperature solution, 14.1 grams (144 mmol) of maleic anhydride was added. The solution was stirred at 115°C for 8 hours, completing the azeotropic removal of approximately 2.2 mL of water to complete the conversion to the maleimide-terminated polyimide. The hot solution was placed in a separatory funnel and washed three times with 300 g of 10% aqueous ethanol. The separatory funnel was stored in a 75°C oven to aid in the separation of the layers. After washing three times, the organic layer was then slowly added to stirred acetone (4 L) to precipitate the product. The product was vacuum filtered using a Buchner funnel and dried overnight in a recirculating oven at 35 °C. After drying, compound 1 (structure shown above) was obtained as a yellow powder in approximately 70% yield.

[0314] Product characterization: FTIR Vmax 2922, 1713, 1602, 1508, 1388, 1348, 1246, 1175, 828, 726, 695; 1H NMR (CDC13) d 8.25 (s, 1H), 7.92 (s, 1H), 3.96 (t, 1H), 3.55 (t, 1H), 1.63 (m, 5H), 1.26 (m, 58H), 0.89 (m, 2H); 13C NMR (CDC13) d 171.2, 168.2, 135.8, 133.7, 125.2, 45.6, 44.8, 42.3, 39.7, 39.6, 31.6, 31.2, 29.7, 29.6, 23.8, 22.2, 21.8, 14.7

[0315] Various physical properties of Compound 1 were measured as described in the Materials and Methods section above. Thin films were analyzed to determine Tg(TMA), CTE(TMA), Dk, and Df. The average molecular weight (Daltons) was determined using the compound in tetrahydrofuran solution. The results are summarized in Table 1 below.

[0316] [Table 1]

[0317] Example 2: Synthesis of Compound 2

[0318] [ka]

[0319] A 1 L reactor was charged with 219.6 g (400 mmol) of PRIAMINE™ 1075, followed by 300 g of NMP, 300 g of toluene, and 30 g of methanesulfonic acid. The mixture was heated to reflux at 115°C for 2 hours, completing the synthesis of the anhydride-terminated polyimide with the azeotropic removal of 7.2 mL of water. To the cooled (room temperature) solution, 47.0 g (480 mmol) of maleic anhydride was added. The solution was refluxed for an additional 8 hours, completing the synthesis of the maleimide-terminated polyimide with the azeotropic removal of 7.2 mL of water. The hot solution was poured into a separatory funnel and washed three times with 300 g of 10% aqueous ethanol. The mixture in the separatory funnel was kept at 75°C to aid in the separation of the layers. The organic layer was separated and dried by the addition of anhydrous magnesium sulfate. The dried solution was transferred to a 1 L rotary evaporator flask, and the solvent was removed under vacuum at 80°C. Compound 2 (structure shown above) was obtained as a light brown viscous resin in approximately 95% yield.

[0320] Product characterization: FTIRVmax 2923, 2854, 1708, 1675, 1441, 1395, 1364, 1298, 1246, 826, 724, 696; 1H NMR (CDC13) d 7.90 (m, 3H), 3.96 (t, 2H), 3.57 (t, 2H), 1.63 (m, 5H), 1.26 (m, 58H), 0.89 (m, 3H); 13C NMR (CDC13) d 194.2, 171.0, 140.0, 135.7, 135.2, 127.9, 123.5, 46.6, 41.9, 35.1, 32.5, 32.0, 29.7, 29.5, 27.8, 22.2, 21.8, 14.1

[0321] Various physical properties of Compound 2 were measured as described in the Materials and Methods section above. Thin films were analyzed to determine Tg(TMA), CTE(TMA), Dk, and Df. The average molecular weight (Daltons) was determined using the compound in tetrahydrofuran solution. The results are summarized in Table 2 below.

[0322] [Table 2]

[0323] Example 3: Synthesis of Compound 3

[0324] [ka]

[0325] A 1 L reactor was charged with 58.2 g (300 mmol) of TCD-diamine and 82.4 g (150 mmol) of PRIAMINE™ 1075, followed by 300 g of NMP, 300 g of toluene, and 30 g of methanesulfonic acid. To this solution was added 89.4 g (410 mmol) of pyromellitic dianhydride. The mixture was heated to reflux at 115°C for 2 hours, and 15 mL of water was removed azeotropically to complete the anhydride-terminated polyimide synthesis. To the cooled (room temperature) solution, 9.4 g (96 mmol) of maleic anhydride was added. The solution was refluxed for an additional 8 hours, and 1.8 mL of water was removed azeotropically to complete the maleimide-terminated polyimide synthesis. The hot solution was poured into a separatory funnel and washed three times with 300 g of 10% aqueous ethanol. The mixture in the separatory funnel was maintained at 75°C to aid in layer separation. After washing three times, the organic phase was added dropwise to stirred isopropyl alcohol to precipitate the product. The precipitate was vacuum filtered using a Buchner funnel and dried overnight at 50°C in a recirculating oven. After drying, compound 3 (structure shown above) was obtained as a slightly yellow powder in approximately 80% yield.

[0326] Characterization of the product: FTIRVmax 2922, 1713, 1602, 1502, 1388, 1348, 1246, 1175, 828, 726, 695; 1H NMR(DMSO) d 8.16(s,1H), 7.0(s,1H), 3.66(m,1H), 3.54(m,2H), 3.32(m,1H), 2.13(m,2H), 1.26(m,26H), 0.90(m,1H); 13C NMR(DMSO) d 171.3, 167.6, 135.8, 135.5, 125.2, 49.6, 46.5, 46.1, 44.4, 41.7, 40.0, 39.3, 35.74, 34.9, 31.8, 30.2, 29.9, 29.3, 25.5, 21.0, 18.5, 14.2

[0327] Various physical properties of compound 3 were measured as described in the Materials and Methods section above. Thin films were analyzed to determine Tg(TMA), CTE(TMA), Dk, and Df. The average molecular weight (Daltons) was determined using the compound in tetrahydrofuran solution. The results are summarized in Table 3 below.

[0328] [Table 3]

[0329] Example 4. Synthesis of Compound 4

[0330] [ka]

[0331] A 2-L reactor was charged with 58.2 g (300 mmol) of TCD-diamine, 164.7 g (300 mmol) of PRIAMINE™ 1075, followed by 500 g of NMP, 500 g of toluene, and 50 g of methanesulfonic acid. To this solution was added 161.8 g (550 mmol) of biphenyltetracarboxylic dianhydride. The mixture was heated to reflux at 115°C for 2 hours, and 20 mL of water was azeotropically removed to complete the anhydride-terminated polyimide synthesis. To the cooled (room temperature) solution, 11.8 g (120 mmol) of maleic anhydride was added. The solution was refluxed for an additional 8 hours, and 2 mL of water was azeotropically removed to complete the maleimide-terminated polyimide synthesis. The hot solution was poured into a separatory funnel and washed three times with 500 g of 10% aqueous ethanol. The mixture in the separatory funnel was maintained at 75°C to aid in layer separation. After washing three times, the organic phase was added dropwise to stirred ethanol to precipitate the product. The precipitate was vacuum filtered using a Buchner funnel and dried overnight at 50°C in a recirculating oven. After drying, compound 4 (structure shown above) was obtained as a slightly yellow powder in approximately 87% yield.

[0332] Product Characterization: FTIR Vmax 2923, 2852, 1704, 1599, 1389, 1367, 1245, 1040, 845, 741, 693; 1H NMR (DMSO) d 8.36 (s, 3H), 7.96 (s, 3H), 7.26 (m, 2H), 7.18 (m, 1H), 4.35 (m, 1H), 3.42 (m, 3H), 2.49 (m, 2H), 2.30 (m, 1H), 1.91 (m, 7H), 1.18 (m, 70H), 1.07 (m, 24H), 0.86 (m, 6H); 13C NMR (DMSO) d 171.1, 168.6, 145.2, 128.9, 128.0, 126.0, 62.0, 52.4, 48.5, 43.6, 43.0, 35.2, 31.8, 29.7, 27.0, 22.5, 21.1, 18.5, 14.1

[0333] Various physical properties of compound 4 were measured as described in the Materials and Methods section above. Thin films were analyzed to determine Tg(TMA), CTE(TMA), Dk, and Df. The average molecular weight (Daltons) was determined using the compound in tetrahydrofuran solution. The results are summarized in Table 4 below.

[0334] [Table 4]

[0335] Example 5: Synthesis of Compound 5

[0336] [ka]

[0337] A 2-L reactor was charged with 58.2 g (300 mmol) of TCD-diamine, 164.7 g (300 mmol) of PRIAMINE™ 1075, followed by 500 g of NMP, 500 g of toluene, and 50 g of methanesulfonic acid. To this solution was added 168.0 g (571 mmol) of biphenyltetracarboxylic dianhydride. The mixture was heated to reflux at 115°C for 2 hours, azeotropically removing 21 mL of water to complete the anhydride-terminated polyimide synthesis. To the cooled (room temperature) solution, 6.9 g (70 mmol) of maleic anhydride was added. The solution was refluxed for an additional 8 hours, azeotropically removing 1 mL of water to complete the maleimide-terminated polyimide synthesis. The hot solution was poured into a separatory funnel and washed three times with 500 g of 10% aqueous ethanol. The mixture in the separatory funnel was maintained at 75°C to aid in layer separation. After washing three times, the organic phase was added dropwise to stirred ethanol to precipitate the product. The precipitate was vacuum filtered using a Buchner funnel and dried overnight at 50°C in a recirculating oven. After drying, compound 5 (structure shown above) was obtained as a slightly yellow powder in approximately 92% yield.

[0338] Product characterization: FTIRVmax 2922,1704,1619,1435,1388,1342,846,739,693, 1HNMR (DMSO) d 8.36(s,2H),7.96(s,2H),7.26(m,2H),7.18(m,1H),4.35(m,3H),3.42(m,3H),2.49(m,2H),2.30(m,1H),1.91(m,7H),1.24(m ,8H),1.07(m,20H),0.86(m,3H), 13CNMR(DMSO) d 171.0, 168.2, 145.1, 128.9, 128.2, 126.0, 61.9, 52.3, 48.5, 43.6, 43.2, 35.5, 31.8, 29.6, 27.0, 22.7, 21.0, 18.5, 14.2

[0339] Various physical properties of compound 5 were measured as described in the Materials and Methods section above. Thin films were analyzed to determine Tg(TMA), CTE(TMA), Dk, and Df. The average molecular weight (Daltons) was determined using the compound in tetrahydrofuran solution. The results are summarized in Table 5 below.

[0340] [Table 5]

[0341] Example 6: Synthesis of Compound 6

[0342] [ka]

[0343] A 1 L reactor was charged with 58.2 g (300 mmol) of TCD-diamine, 54.9 g (100 mmol) of PRIAMINE™ 1075, followed by 300 g of NMP, 300 g of toluene, and 30 g of methanesulfonic acid. To this solution was added 112.1 g (381 mmol) of biphenyltetracarboxylic dianhydride. The mixture was heated to reflux at 115°C for 2 hours, and 21 mL of water was removed azeotropically to complete the anhydride-terminated polyimide synthesis. To the cooled (room temperature) solution, 6.9 g (70 mmol) of maleic anhydride was added. The solution was refluxed for an additional 8 hours, and 1 mL of water was removed azeotropically to complete the maleimide-terminated polyimide synthesis. The hot solution was poured into a separatory funnel and washed three times with 300 g of 10% aqueous ethanol. The mixture in the separatory funnel was maintained at 75°C to aid in layer separation. After washing three times, the organic phase was added dropwise to stirred ethanol to precipitate the product. The precipitate was vacuum filtered using a Buchner funnel and dried overnight at 50°C in a recirculating oven. After drying, compound 6 (structure shown above) was obtained as a slightly yellow powder in approximately 89% yield.

[0344] Product Characterization: FTIR Vmax 2946, 1704, 1613, 1544, 1506, 1393, 839, 742, 695, 677; 1H NMR (DMSO) d 8.26 (s, 1H), 7.98 (s, 1H), 7.26 (m, 1H), 7.17 (m, 2H), 7.0 (m, 1H), 3.30 (m, 32H), 2.69 (s, 4H), 2.29 (s, 4H), 2.18 (t, 3H), 1.91 (m, 6H), 1.46 (m, 6H), 1.23 (m, 12H), 0.86 (m, 3H); 13C NMR (DMSO) d 171.0, 166.9, 134.4, 128.9, 128.2, 125.3, 48.4, 30.1, 29.0, 21.0, 17.2

[0345] Various physical properties of compound 6 were measured as described in the Materials and Methods section above. Thin films were analyzed to determine Tg(TMA), CTE(TMA), Dk, and Df. The average molecular weight (Daltons) was determined using the compound in tetrahydrofuran solution. The results are summarized in Table 6 below.

[0346] [Table 6]

[0347] Example 7. RDL formulation Twenty samples (1-20) were prepared according to the formulations given in Table 7 ("Compositions"). The samples contained various combinations of compounds 1-6, one or more reactive diluents, SR-833S (S8), SR-454 (S4), and / or tris(2-acryloxyethyl) isocyanurate (TA). Each sample also contained an initiator (2% IRGACURE™ 819 and 1% DCP), and a coupling agent (1% KBM-303 and 1% KBM-573).

[0348] Physical properties of film formulations Thin films were prepared from the compounds or compositions by pouring a solution of approximately 35% (w / v) solids in anisole into a square aluminum mold (12 × 12 × 0.2 cm) treated with a release agent. The filled mold was placed in a vacuum chamber for 5 minutes to remove dissolved gases. The mold was then placed in an oven at 100 °C for approximately 5 hours to evaporate the solvent and yield an uncured film. The mold was then placed in a UV chamber and UV-cured for 1 minute using an Electro-lite ELC-4001 UV flood system (Electro-Lite Corporation; Bethel, CT) equipped with a UV-A high-pressure mercury lamp. The sample was then covered with an i-line bandpass filter (365 nm) from Asahi Spectra USA, Inc. (Torrance, CA). The mold was then transferred to a 175 °C oven for 30 minutes to fully cure the film. After cooling, a 200-300 micron thick film was removed from the mold. Samples were used to measure Tg, CTE, Dk, and Df. Dogbone specimens were also used to determine tensile strength (TS) and elongation (%E) as described in the Materials and Methods section above. The results are summarized in Table 7 below.

[0349] Photolithography An aliquot of the formulation shown in Table 7 was placed on a silicon wafer and spin-coated at 1,100 rpm for 10 seconds to form a film. The spin-coated film was dried in an oven at approximately 100°C for 10 minutes. A photomask was placed on the spin-coated wafer and irradiated with 500 mJ / cm using an I-line filter. 2 The wafers were exposed to I-line (365 nm). The wafers were then developed by placing them in a solvent bath for 1 minute. As shown in Table 7, "Developing Solvents," various combinations of solvents, including one or more of cyclopentanone (CP), cyclohexanone (CH), ethanol (E), and propylene glycol monomethyl ether acetate (PGMEA), were used for development.

[0350] In successful photolithography, the exposed (hardened) areas remain intact on the substrate, while the unexposed (masked) areas are washed away in a developing solvent bath. After development, the wafer was placed in a 175 °C oven for 30 minutes to dry and completely adhere to the wafer. The film was analyzed using a Dektak surface profiler (Bruker Corp.; Ettlingen, DE) and showed a very well-developed surface with a thickness of approximately 5-10 μm.

[0351] [Table 7]

[0352] Traditional passivation and RDL polymer methods involve applying an acrylated polyamic acid solution to a silicon wafer or chip and then developing the sample using photolithography. At this stage, the film is a crosslinked polyamic acid polymer, so its properties are very poor. The ultimate properties are achieved by oven-curing the sample at temperatures above 200°C for several hours. After this, a very high Tg (approximately 200°C) is achieved, with a tensile strength exceeding 80 MPa and an elongation exceeding 50%. However, if mass production of high-performance passivation and RDL layers is required, a polymer with low temperature and fast curing is advantageous.

[0353] Initial experiments (not shown) were performed with UV curing at low temperatures (i.e., room temperature), and individual high Tg polymers or oligomers, including compounds 3-6, produced poor results. The results indicated that complete UV curing did not occur with compounds 3-6 at low temperatures. Specifically, these initial single polyimide formulations were applied to silicon wafers and exposed to UV (>3000 mJ / cm). 2 ) for 2 minutes showed insufficient UV curing. Such films washed off the substrate within seconds of exposure to the developer. While not wishing to be bound by theory, chemical reactions are most efficient in solution or with gaseous reagents, promoting kinetic conditions that facilitate the interactions between reactive groups necessary to ensure polymerization and crosslinking. Heat further accelerates the process. Therefore, reactions in glassy and / or high-melting films immobilized on substrates are expected to be less efficient than reactions in solution. However, in this case, the UV curing reaction may have been hindered or slowed at room temperature, resulting in virtually no polymerization or crosslinking.

[0354] It was hypothesized that successful implementation of UV initiation without additional heating would require the inclusion of reactants with lower melting temperatures and / or the addition of reactive diluents that can soften and solvate the reactants in the film formulation, thereby accelerating curing. Optimal properties are believed to be obtained by UV curing followed by a short time (e.g., seconds or minutes rather than hours) at a moderately high temperature (above room temperature but below the 200°C of conventional oven curing).

[0355] The results obtained with the formulations listed in Table 7 confirmed the hypothesis that formulations containing a combination of relatively high average molecular weight polyimides (compounds 3-6) and smaller, flexible polyimide oligomers (compounds 1 and 2) can be UV cured and photoimaged. Each composition cured sufficiently and supported pattern formation.

[0356] The addition of acrylic monomers (di- and tri-functional) also aids UV curing. Low-viscosity acrylics such as tricyclodecane dimethanol diacrylate (SR-833S) and ethoxylated trimethylolpropane triacrylate (SR-454) have proven most useful. These two monomers have viscosities below 200 centipoise and Tg values ​​of approximately 180°C and 120°C, respectively. Tris(2-acryloxyethyl) isocyanurate has an even higher Tg of approximately 270°C. However, this material is a waxy solid and does not improve UV curing as much as SR-833S or SR-454.

[0357] Several compositions with Tg values ​​close to 100°C were obtained. Of these, materials with high elongation are crucial. One of the industry requirements is to have flexible materials that will not crack or shatter at very low temperatures, such as when a cell phone is dropped. Therefore, elongations approaching 50% may be required to pass this type of test. Several compositions, including 8, 17, 18, and 19, are sufficient to meet the requirement.

[0358] Because RDL materials are used in modern high-frequency electronics, users of these materials expect them to have better Dk and Df than traditional RDL materials used in industry. This means a Dk of less than 2.7 and a Df of less than 0.005. Based on the results in Table 7, it is safe to say that Dk and Df expectations are met and exceeded.

[0359] Composition No. 8, with a Tg of 100°C and a CTE of 17 ppm, had good tensile strength and 40% elongation. The Df@20 GHz of this material was 0.0035. A solution of this material was spin-coated onto a silicon wafer and UV-cured (500 mJ / cm). 2 ) and developed in an 85% cyclopentanone and 15% ethanol solution. Image 1 is a photograph of the developed material, showing a 5 μm thick film with very well developed 10 μm vias.

[0360] Figures 7A and B show the high-resolution detailed photolithography achieved with Formulation 8. Figure 7A shows a photomask with UV-opaque areas (shown in black) including frame 400a, 10 μm filled circles 300a and 310a (which form vias), and the numbers "1" (320a) and "0" (330a) on a transparent background 500 (white blank). Figure 7B is a micrograph of a 5 μm thick film prepared using the photomask shown in Figure 7A.

[0361] Films were prepared by spin-coating Formulation 8 onto an 8-inch silicon wafer at 1,000 rpm for 10 seconds, followed by drying on a hot plate at 100 °C for approximately 3 minutes. The mask in Figure 7A was placed on the film, and 300 mJ / cm 2 The unmasked areas of the film were selectively cured by UV irradiation (i-line, 365 nm), thereby forming a pattern. The wafer-bonded film was then exposed to a developing solvent (cyclopentanone) to remove the unexposed (uncured) areas, leaving behind a detailed UV-cured pattern.

[0362] Each via (300b, 310b) and number (320b, 330b) was a distinct void in the film, with sharp boundaries without smearing between the masked characters. The unmasked areas cured to a uniform 5 μm thickness. The "fuzziness" and darkness of the via-character boundaries are 3D visual artifacts representing sloping contour areas (such as via walls) and reflect the fact that the film is 5 μm thick, while the via itself is 10 μm in diameter, slightly twice the thickness of the film.

Claims

1. 1. A passivation formulation comprising two or more curable functionalized polyimide compounds, wherein the two or more curable functionalized polyimide compounds are condensation products of diamines and acid anhydrides; 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 【Chemistry 4】 【Transformation 5】 the first at least one polyimide is a curable functionalized flexible polyimide selected from Compound 1, Compound 2, and combinations thereof; and the second at least one polyimide is a curable functionalized polyimide selected from Compound 3, Compound 4, Compound 6, and combinations thereof; the first polyimide has a coefficient of thermal expansion (CTE) of 150 ppm / °C or greater; The second polyimide has a coefficient of thermal expansion (CTE) of less than 100 ppm / °C.

2. 10. The passivation formulation of claim 1, wherein the first at least one curable functionalized flexible polyimide comprises 15% to 80% by weight of the formulation.

3. the second at least one curable functionalized polyimide comprises 45% to 75% by weight of the formulation; 10. The passivating formulation of claim 1 having a glass transition temperature (Tg) of at least 100°C.

4. 2. The passivation formulation of claim 1, wherein the first at least one curable functionalized flexible polyimide comprises Compound 1 and the second at least one curable functionalized polyimide comprises Compound 4.

5. 10. The passivation formulation of claim 1, wherein the passivation formulation when cured has a Tg of at least 90°C.

6. 10. The passivation formulation of claim 1 further comprising: a) at least one reactive diluent or co-curing agent; or b) at least one adhesion promoter; or c) at least one coupling agent; or d) at least one UV initiator; or e) at least one solvent, or f) any combination thereof.

7. the second at least one curable functionalized polyimide comprises 65% to 80% by weight of the formulation; the at least one reactive diluent comprises an acrylic monomer; the at least one reactive diluent comprises 10% to 30% by weight of the formulation; the at least one reactive diluent has a Tg greater than 100°C; the at least one coupling agent comprising 2% by weight of the formulation; The passivating formulation of claim 6 , wherein the at least one coupling agent comprises a silane coupling agent.

8. 1. A method for passivating an electronic element or any part thereof, comprising the steps of: a) applying a layer of the passivation formulation of claim 1 to at least a portion of an electronic component; and b) A curing step in which the passivation formulation is cured, thereby passivating the electronic elements.

9. A passivated electronic component comprising a cured layer of the passivation formulation of claim 1.

10. 1. An electronic device having a redistribution layer or a passivation layer, comprising: a) electronic devices that are semiconductor wafers, chips, wafer level packages, microelectromechanical systems (MEMS), passivation layers with positive temperature coefficients (PTC), fan-out rewired chips or circuit boards; and b) a redistribution layer or passivation layer comprising a cured layer of the passivation formulation of claim 1 disposed on at least one surface of said electronic device or component thereof.

11. 1. A method for rewiring I / O pads of a chip, comprising the steps of: a) applying a first layer of the passivation compound of claim 1 to the surface of the chip, covering at least one line from an I / O pad to a new I / O pad location; b) metallizing the lines, thereby forming metallized lines; c) applying a second layer of the passivation compound of claim 1 to the surface of the chip, covering at least the metallized lines; d) removing the portion of the first layer covering the metallized lines of the new I / O pad; and e) curing the first and second layers of passivation compound, thereby rewiring the I / O pads of the chip;

Images