Resin composition for die attach film having excellent performance with large die applications

Abstract

Aspects of the present disclosure relate to compositions for forming films and the use of the films in large chip applications. In certain aspects, the present disclosure relates to compositions comprising two or more resins, optionally one or more inorganic fillers, and one or more core-shell additives, and a curing agent package, to films prepared from the disclosed compositions, and to cured films obtained after curing the disclosed compositions. In certain aspects, cured films obtained after curing the disclosed compositions have particular physical properties and / or combinations of physical properties.

Description

Technical Field

[0001] Aspects of the present disclosure relate to compositions for forming films and the use of such films in large die applications. In certain aspects, the present disclosure relates to compositions comprising two or more resins, optionally one or more inorganic fillers, one or more core-shell additives, and a curative package, to films prepared from the disclosed compositions, and to cured films obtained after curing the disclosed compositions. In certain aspects, the cured films obtained after curing the disclosed compositions have specific physical properties and / or combinations of physical properties. Background Art

[0002] When considering next-generation high-performance packaging, the materials industry faces the need to improve the high-temperature properties of film materials (e.g., die attach film materials). Achieving this goal can bring benefits such as higher thermal stability and thus higher reliability in applications across the automotive, computing, networking, and telecommunications industries. Characteristics that may be associated with improved high-temperature properties of film materials include a relatively high Tg (glass transition temperature) and a relatively high modulus at relatively high temperatures (e.g., 200 °C).

[0003] For reference, Figure 1 is an example showing the application of a die attach film to bond a silicon die to the surface of a metal lead frame. In Figure 1 , 1 is a molding compound, 2 is a wirebond, 3 is a silicon die, 4 is a die attach film adhesive, 5 is a copper lead frame, and 6 is a substrate.

[0004] Currently, commercially available die attach films are mainly used in electronic packaging assemblies with laminate bismaleimide-triazine (“BT”) substrates for memory stack die applications. Many of these die attach films are based on epoxy or epoxy / acrylate chemistries and generally do not exhibit high adhesion to metal substrates.

[0005] Therefore, it is desirable to improve the performance of die attach films on metal substrates and / or in large die applications. Summary of the Invention

[0006] In view of at least the considerations discussed above, attention is focused on compositions comprising two or more resins, optionally one or more inorganic fillers, and one or more core-shell additives, and a curative package, on films prepared from such compositions, and on cured films obtained after curing such compositions.

[0007] Accordingly, the present disclosure provides a composition particularly suitable for use in chip attach film applications, such as non-conductive chip attach film applications. There is a desire for such a composition that has advantageous properties making it highly suitable for use in the automotive industry where high reliability requirements are desired, such as high adhesion to the surfaces of various metal leadframes including copper, silver, and PPF (NiPdAu-plated copper leadframes where Au is the outermost surface, Ni is the innermost surface, and the Pd layer is sandwiched therebetween).

[0008] Chip attach films prepared from these compositions exhibit low stress, which translates to low warpage, which is particularly advantageous for large chip applications.

[0009] In some embodiments, aspects of the present disclosure relate to a composition comprising:

[0010] (a) Two or more resins selected from: (i) at least one of a maleimide-containing resin, a nadimide-containing resin, or an itaconimide-containing resin, and (ii) an epoxy resin;

[0011] (b) Core-shell particles comprising a polymeric material having elastomeric or rubber-like properties surrounded by a shell of an inelastic polymer material;

[0012] (c) Optionally present inorganic filler;

[0013] (d) A curing agent package comprising

[0014]

[0015] wherein herein R1, R2, R3, and R4 are each independently selected from H, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 2 to 5 carbon atoms, and a hydroxyalkyl group having 1 to 4 carbon atoms,

[0016]

[0017] wherein herein R1, R2, R3, and R4 are each independently selected from H, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 2 to 5 carbon atoms, and a hydroxyalkyl group having 1 to 4 carbon atoms, and

[0018]

[0019] wherein herein R1, R2, R3, R4, R5, and R6 are each independently selected from H, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 2 to 5 carbon atoms, and a hydroxyalkyl group having 1 to 4 carbon atoms, and each of R2 and R3 and R5 and R6 together independently form a cyclic ring of 3 to 7 atoms; and

[0020] (e) One or more additives selected from adhesion promoters and film formers.

[0021] In some aspects, the composition exhibits at least the following physical properties after being B-staged to a film:

[0022] The DSC has an onset temperature of 160 °C to 180 °C,

[0023] The DSC has a peak temperature of 180 °C to 210 °C, and

[0024] The heat of reaction > 30 J / g.

[0025] In some aspects, the composition exhibits at least the following physical properties after being B-staged to a film: When laminated to a 7 mm × 7 mm chip and after exposure to a temperature of about 175 °C for a period of about 1 hour, the chip is measured and shows a warp of less than about 100 μm.

[0026] In some aspects, the composition exhibits at least the following physical properties after being B-staged to a film: When laminated to a metal lead frame or BT substrate on a 3 mm × 3 mm chip and after exposure to a temperature of about 175 °C for a period of about 4 hours, the film adheres to the metal lead frame, showing an adhesion force of at least 3 kgf per chip.

[0027] In some aspects, the composition exhibits at least the following physical properties after being B-staged to a film:

[0028] DMA (Dynamic Mechanical Analysis), which shows a storage modulus < 2500 MPa at 25 °C, and

[0029] The glass transition temperature Tg > 200 °C.

[0030] In some aspects, the composition exhibits at least the following physical properties after being B-staged to a film:

[0031] DMA (Dynamic Mechanical Analysis), which shows a storage modulus > 50 MPa at 100 °C, and

[0032] The glass transition temperature Tg > 200 °C.

[0033] In some aspects, the composition exhibits at least the following physical properties after being B-staged to a film:

[0034] DMA (Dynamic Mechanical Analysis), which shows a storage modulus > 20 MPa at 150 °C, and

[0035] The glass transition temperature Tg > 200 °C.

[0036] In some aspects, the composition exhibits at least the following physical properties after being B-staged into a film:

[0037] DMA (Dynamic Mechanical Analysis), which shows a storage modulus > 10 MPa at 200 °C, and

[0038] a glass transition temperature Tg > 200 °C.

[0039] In some aspects, after being applied to a metal lead frame and cured at a temperature of 260 °C, the composition shows the following die shear strengths: > 9 kgf / die on a copper metal lead frame and > 5 kgf / die on a silver metal lead frame.

[0040] In some embodiments, aspects of the present disclosure relate to a curing agent package that comprises:

[0041]

[0042] wherein herein R1, R2, R3, and R4 are each independently selected from H, alkyl having 1 to 4 carbon atoms, alkoxy having 2 to 5 carbon atoms, and hydroxyalkyl having 1 to 4 carbon atoms,

[0043]

[0044] wherein herein R1, R2, R3, and R4 are each independently selected from H, alkyl having 1 to 4 carbon atoms, alkoxy having 2 to 5 carbon atoms, and hydroxyalkyl having 1 to 4 carbon atoms, and

[0045]

[0046] wherein herein R1, R2, R3, R4, R5, and R6 are each independently selected from H, alkyl having 1 to 4 carbon atoms, alkoxy having 2 to 5 carbon atoms, and hydroxyalkyl having 1 to 4 carbon atoms, and each of R2 and R3 and R5 and R6 together independently forms a cyclic ring of 3 to 7 atoms. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Examples are presented showing the application of a die attach film to bond a silicon die to the surface of a metal lead frame.

[0048] Figure 2 A schematic diagram of a process for using a die attach film in an application is presented.

[0049] Figure 3Presents the DMA (Dynamic Mechanical Analysis) data of an exemplary composition of the present disclosure (Sample 5 of the present invention after post-curing at 175 °C for 1 hour) in terms of storage modulus (measured in MPa) as a function of increasing temperature (measured in °C), loss modulus (measured in MPa) as a function of increasing temperature (measured in °C), and tan δ (measured in °C) as a function of increasing temperature (measured in °C).

[0050] Figure 4 Presents the DSC (Differential Scanning Calorimetry) data of an exemplary composition of the present disclosure (Sample 5 of the present invention) in terms of heat flow (measured in W / g) as a function of increasing temperature (measured in °C).

[0051] Figure 5 Presents the melt viscosity data of an exemplary composition of the present disclosure (Sample 5 of the present invention). Detailed Description

[0052] The disclosed compositions and methods can be more readily understood by reference to the following detailed description in conjunction with the accompanying drawings, which form a part of the present disclosure.

[0053] According to the present disclosure, in some embodiments, as described above, there is provided a composition comprising:

[0054] (a) Two or more resins selected from: (i) at least one of a maleimide-containing resin, a nadimide-containing resin, or an itaconimide-containing resin, and (ii) an epoxy resin;

[0055] (b) Core-shell particles comprising a polymeric material having elastomeric or rubber-like properties surrounded by a shell containing a non-elastomeric polymeric material;

[0056] (c) Optionally present inorganic filler;

[0057] (d) A curing agent package comprising

[0058]

[0059] wherein herein R1, R2, R3, and R4 are each independently selected from H, alkyl having 1 to 4 carbon atoms, alkoxy having 2 to 5 carbon atoms, and hydroxyalkyl having 1 to 4 carbon atoms,

[0060]

[0061] wherein herein R1, R2, R3, and R4 are each independently selected from H, alkyl having 1 to 4 carbon atoms, alkoxy having 2 to 5 carbon atoms, and hydroxyalkyl having 1 to 4 carbon atoms, and

[0062]

[0063] Wherein R1, R2, R3, R4, R5 and R6 are each independently selected from H, alkyl having 1 to 4 carbon atoms, alkoxy having 2 to 5 carbon atoms, and hydroxyalkyl having 1 to 4 carbon atoms, and each of R2 and R3 and each of R5 and R6 together independently form a cyclic ring of 3 to 7 atoms; and

[0064] (e) one or more additives selected from adhesion promoters and film formers.

[0065] In some embodiments, with respect to the resin component (a)(i), the maleimide-containing resin, nadimide-containing resin, or itaconic imide-containing resin is represented by the following formulas, respectively:

[0066]

[0067] Wherein:

[0068] m is from 1 to 15,

[0069] p is from 0 to 15,

[0070] each R 2 is independently selected from hydrogen or C 1-6 alkyl, and

[0071] J is a monovalent or polyvalent group containing an organic group and / or a siloxane group.

[0072] In some embodiments, J is a monovalent or polyvalent group selected from the following:

[0073] - a hydrocarbon group or a substituted hydrocarbon group generally having from about 6 to about 500 carbon atoms, wherein the hydrocarbon group is selected from alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, alkylaryl, arylalkyl, arylalkenyl, alkenylaryl, arylalkynyl or alkynylaryl, provided that X can be aryl only when X contains a combination of two or more different types;

[0074] - a subhydrocarbon group or a substituted subhydrocarbon group generally having from about 6 to about 500 carbon atoms, wherein the subhydrocarbon group is selected from alkylene, alkenylene, alkynylene, cycloalkylene, cycloalkenylene, arylene, alkylarylene, arylalkylene, arylalkenylene, alkenylarylene, arylalkynylene or alkynylarylene,

[0075] - substituted or unsubstituted C6-C 10 aryl;

[0076] - a heterocyclic or substituted heterocyclic group generally having from about 6 to about 500 carbon atoms,

[0077] - polysiloxane,

[0078] - a polysiloxane-polyurethane block copolymer, or

[0079] - a combination of one or more of the above with a linker selected from: covalent bond, -O-, -S-, -NR-, -NR-C(O)-, -NR-C(O)-O-, -NR-C(O)-NR-, -S-C(O)-, -S-C(O)-O-, -S-C(O)-NR-, -O-S(O)2-, -O-S(O)2-O-, -O-S(O)2-NR-, -O-S(O)-, -O-S(O)-O-, -O-S(O)-NR-, -O-NR-C(O)-, -O-NR-C(O)-O, -O-NR-C(O)-NR-, -NR-O-C(O)-, -NR-O-C(O)-O-, -NR-O-C(O)-NR-, -O-NR-C(S)-, -O-NR-C(S)-O-, -O-NR-C(S)-NR-, -NR-O-C(S)-, -NR-O-C(S)-O-, -NR-O-C(S)-NR-, -O-C(S)-, -O-C(S)-O-, -O-C(S)-NR-, -NR-C(S)-, -NR-C(S)-O-, -NR-C(S)-NR-, -S-S(O)2-, -S-S(O)2-O-, -S-S(O)2-NR-, -NR-O-S(O)-, -NR-O-S(O)-O-, -NR-O-S(O)-NR-, -NR-O-S(O)2-, -NR-O-S(O)2-O-, -NR-O-S(O)2-NR-, -O-NR-S(O)-, -O-NR-S(O)-O-, -O-NR-S(O)-NR-, -O-NR-S(O)2-O-, -O-NR-S(O)2-NR-, -O-NR-S(O)2-, -O-P(O)R2-, -S-P(O)R2- or -NR-P(O)R2-; where each R is independently hydrogen, alkyl or substituted alkyl.

[0080] In some embodiments, J is a substituted or unsubstituted C6 aryl, oxyalkyl, thioalkyl, aminoalkyl, carboxyalkyl, oxyalkenyl, thioalkenyl, aminoalkenyl, carboxyalkenyl, oxyalkynyl, thioalkynyl, aminoalkynyl, carboxyalkynyl, oxycycloalkyl, thiocycloalkyl, aminocycloalkyl, carboxycycloalkyl, oxycycloalkenyl, thiocycloalkenyl, aminocycloalkenyl, carboxycycloalkenyl, heterocyclic, oxacycle, thiacycle, aminoheterocycle, carboxyheterocycle, oxyaryl, thioaryl, aminoaryl, carboxyaryl, heteroaryl, oxaheteroaryl, thiaheteroaryl, aminoheteroaryl, carboxyheteroaryl, oxyalkylaryl, thioalkylaryl, aminoalkylaryl, carboxyalkylaryl, oxyarylalkyl, thioarylalkyl, aminoarylalkyl, carboxyarylalkyl, oxyarylalkenyl, thioarylalkenyl, aminoarylalkenyl, carboxyarylalkenyl, oxyalkenylaryl, thioalkenylaryl, aminoalkenylaryl, carboxyalkenylaryl, oxyarylalkynyl, thioarylalkynyl, aminoarylalkynyl, carboxyarylalkynyl, oxyalkynylaryl, thioalkynylaryl, aminoalkynylaryl, or carboxyalkynylaryl, oxyalkylene, thioalkylene, aminoalkylene, carboxyalkylene, oxyalkenylene, thioalkenylene, aminoalkenylene, carboxyalkenylene, oxyalkynylene, thioalkynylene, aminoalkynylene, carboxyalkynylene, oxycycloalkylene, thiocycloalkylene, aminocycloalkylene, carboxycycloalkylene, oxycycloalkenylene, thiocycloalkenylene, aminocycloalkenylene, carboxycycloalkenylene, oxyarylene, thioarylene, aminoarylene, carboxyarylene, oxyalkylarylene, thioalkylarylene, aminoalkylarylene, carboxyalkylarylene, oxyarylenealkylene, thioarylenealkylene, aminoarylenealkylene, carboxyarylenealkylene, oxyarylenealkenylene, thioarylenealkenylene, aminoarylenealkenylene, carboxyarylenealkenylene, oxyalkenylenearylene, thioalkenylenearylene, aminoalkenylenearylene, carboxyalkenylenearylene, oxyarylenealkynylene, thioarylenealkynylene, aminoarylenealkynylene, carboxyarylenealkynylene, oxyalkynylenearylene, thioalkynylenearylene, aminoalkynylenearylene, carboxyalkynylenearylene, heteroarylene, oxaheteroarylene, thiaheteroarylene, aminoheteroarylene, carboxyheteroarylene, a heteroatom-containing divalent or polyvalent cyclic moiety, an oxygen heteroatom-containing divalent or polyvalent cyclic moiety, a sulfur heteroatom-containing divalent or polyvalent cyclic moiety, an amino heteroatom-containing divalent or polyvalent cyclic moiety, or a carboxy heteroatom-containing divalent or polyvalent cyclic moiety.

[0081] In some embodiments, the maleimide-containing resin is represented by the following formula:

[0082]

[0083] Wherein:

[0084] Each R is independently selected from H and substituted or unsubstituted alkyl;

[0085] Each m is independently selected from 0, 1, 2, 3, and 4; and

[0086] n is 0, 1, 2, 3, 4, or 5.

[0087] In some embodiments, the composition comprises a compound represented by the formula:

[0088]

[0089] This compound is abbreviated as BMI-5100 (chemical name: 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide; Daiwa Kasei, Japan), which is a compound having a number average molecular weight of about 300 as measured by gel permeation chromatography (GPC).

[0090] In some embodiments, the maleimide-containing resin is represented by the formula:

[0091]

[0092] wherein n is 0, 1, 2, 3, 4, or 5.

[0093] In some embodiments, the maleimide-containing resin is a BMI resin having a maleimide equivalent weight of 180 to 400. The maleimide equivalent weight is the weight of the resin containing one equivalent of maleimide functional groups in grams. In some embodiments, the maleimide-containing resin is a BMI resin having a maleimide equivalent weight of 220. In some embodiments, the maleimide-containing resin is a BMI resin having a maleimide equivalent weight of 300. In some embodiments, the maleimide-containing resin is a BMI resin having a maleimide equivalent weight of about 400. In some embodiments, the maleimide-containing resin is a BMI resin having a maleimide equivalent weight of about 390 to about 400. In some embodiments, the maleimide-containing resin is a BMI resin having a maleimide equivalent weight of 390 to 400.

[0094] In some embodiments, the maleimide-containing resin is included in an amount of from about 1 wt% to about 20 wt%. In some embodiments, the maleimide-containing resin is included in an amount of from about 1 wt% to about 15 wt%. In some embodiments, the maleimide-containing resin is included in an amount of from about 3 wt% to about 15 wt%. In some embodiments, the maleimide-containing resin is included in an amount of from about 1 wt% to about 5 wt%. In some embodiments, the maleimide-containing resin is included in an amount of from about 5 wt% to about 20 wt%. In some embodiments, the maleimide-containing resin is included in an amount of from about 5 wt% to about 15 wt%. In some embodiments, the maleimide-containing resin is included in an amount of from about 10 wt% to about 20 wt%. In some embodiments, the maleimide-containing resin is included in an amount of from about 10 wt% to about 15 wt%. In some embodiments, the maleimide-containing resin is included in an amount of from about 12 wt% to about 17 wt%. In some embodiments, the maleimide-containing resin is included in an amount of about 10 wt%, about 11 wt%, about 12 wt%, about 13 wt%, about 14 wt%, about 15 wt%, about 16 wt%, about 17 wt%, about 18 wt%, about 19 wt% or about 20 wt%.

[0095] In some embodiments, the itaconimide-containing resin is represented by the following formula:

[0096]

[0097] wherein Ar is a substituted or unsubstituted aryl group.

[0098] In some embodiments, the itaconimide-containing resin is represented by the following formula:

[0099]

[0100] In some embodiments, nadicimide is represented by the following formula:

[0101]

[0102] wherein:

[0103] -Ar is a substituted or unsubstituted aryl group, and

[0104] -R is selected from H, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group.

[0105] In some embodiments, optionally, the maleimide-containing resin, the nadicimide-containing resin, or the itaconimide-containing resin (a)(i) is selected from:

[0106]

[0107] wherein n is from 0 to 2,

[0108]

[0109] wherein R is an alkyl group having 1 to 4 carbon atoms, phenyl, or alkylphenyl having 7 to 11 carbon atoms, and n is from 1 to 12, and

[0110]

[0111] wherein R is an alkyl group having 1 to 4 carbon atoms or phenyl, X is diarylalkylene, and n is from 1 to 2.

[0112] As described above, the compositions of the present disclosure comprise, among other components, in particular epoxy resins. A variety of epoxy resins are contemplated for use herein, such as liquid bisphenol A-based epoxy resins, solid bisphenol A-based epoxy resins, liquid bisphenol F-based epoxy resins (e.g., EPICLON EXA-835LV), polyfunctional epoxy resins based on phenol-novolac resins, dicyclopentadiene-based epoxy resins (e.g., EPICLON HP-7200L), naphthalene-based epoxy resins, etc., and mixtures of any two or more thereof.

[0113] Exemplary epoxy resins contemplated for use herein include diepoxides of alicyclic alcohols, hydrogenated bisphenol A (commercially available as EPALLOY 5000), bifunctional alicyclic glycidyl esters of hexahydrophthalic anhydride (commercially available as EPALLOY 5200), EPICLON EXA-835LV, EPICLON HP-7200L, etc., and mixtures of any two or more thereof.

[0114] In certain embodiments, the epoxy resin may comprise a combination of two or more different bisphenol-based epoxy resins. These bisphenol-based epoxy resins may be selected from bisphenol A, bisphenol F, or bisphenol S epoxy resins, or combinations thereof. Additionally, two or more different bisphenol epoxy resins within the same type of resin (e.g., A, F, or S) may be used.

[0115] Commercially available examples of bisphenol epoxy resins used herein include bisphenol F type epoxy resins (e.g., RE-404-S from Nippon Kayaku, Japan, and EPICLON 830 (RE1801), 830S (RE1815), 830A (REI 826), and 830W from Dai Nippon Ink & Chemicals, Inc., and RSL1738 and YL-983U from Resolution) and bisphenol A type epoxy resins (e.g., YL-979 and 980 from Resolution).

[0116] The bisphenol epoxy resins commercially available from Dai Nippon and described above are promoted as liquid undiluted epichlorohydrin-bisphenol F epoxy resins having a much lower viscosity than conventional epoxy resins based on bisphenol A epoxy resins and having physical properties similar to those of liquid bisphenol A epoxy resins. The bisphenol F epoxy resins have a lower viscosity than bisphenol A epoxy resins, all other aspects being the same between the two types of epoxy resins, which provides a lower viscosity and thus a fast-flowing underfill sealant material. The EEW of these four bisphenol F epoxy resins is 165 to 180. The viscosity at 25 °C is 3000 to 4500 cps (except for RE1801, the upper limit of whose viscosity is 4000 cps). For RE1815 and 830W, the hydrolyzable chloride content is reported to be 200 ppm, and for RE1826, the hydrolyzable chloride content is reported to be 100 ppm.

[0117] The bisphenol epoxy resins commercially available from Resolution and described above are promoted as liquid epoxy resins containing low chlorides. The bisphenol A epoxy resins have an EEW (g / eq) of 180 to 195 and a viscosity at 25 °C of 100 to 250 cps. The total chloride content of YL-979 is reported to be 500 to 700 ppm, and the total chloride content of YL-980 is reported to be 100 to 300 ppm. The bisphenol F epoxy resins have an EEW (g / eq) of 165 to 180 and a viscosity at 25 °C of 30 to 60 cps. The total chloride content of RSL-1738 is reported to be 500 to 700 ppm, and the total chloride content of YL-983U is reported to be 150 to 350 ppm.

[0118] In addition to bisphenol epoxy resins, other epoxy compounds are considered for use as the epoxy resin (a)(ii) of the disclosed compositions. For example, alicyclic epoxy resins such as 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate can be used. Monofunctional, difunctional or polyfunctional reactive diluents can also be used to adjust the viscosity of the resulting resin material and / or lower the Tg of the resulting resin material. Exemplary reactive diluents include butyl glycidyl ether, cresyl glycidyl ether, polyethylene glycol glycidyl ether, polypropylene glycol glycidyl ether, and the like.

[0119] Also suitable for use herein are other epoxy resins including polyglycidyl derivatives of phenolic compounds such as those commercially available under the trade name EPON, such as EPON 828, EPON 1001, EPON 1009, and EPON 1031 from Resolution; DER 331, DER 332, DER 334, and DER 542 from Dow Chemical Co.; and BREN-S from Nippon Kayaku. Other suitable epoxy resins include polyepoxides prepared from polyols and the like and polyglycidyl derivatives of phenol-formaldehyde novolacs, the latter being, for example, DEN 431, DEN 438, and DEN 439 from Dow Chemical. Cresol analogs are also commercially available under the trade name ARALDITE, such as ARALDITE ECN 1235, ARALDITE ECN 1273, and ARALDITE ECN 1299 from Ciba Specialty Chemicals Corporation. SU-8 is a bisphenol A type epoxy novolac available from Resolution. Polyglycidyl adducts of amines, amino alcohols, and polycarboxylic acids can also be used in the present invention, and commercially available resins thereof include GLYAMINE 135, GLYAMINE 125, and GLYAMINE 115 from F.I.C. Corporation; ARALDITE MY-720, ARALDITE 0500, and ARALDITE 0510 from Ciba Specialty Chemicals; and PGA-X and PGA-C from Sherwin-Williams Co.

[0120] Suitable monofunctional epoxy co-reactant diluents for optional use herein also include those having a viscosity lower than the viscosity of the epoxy component, and the viscosity of such diluents is generally less than about 250 cps. The monofunctional epoxy co-reactant diluent can have an epoxy group with an alkyl group having about 6 to about 28 carbon atoms, and examples thereof include C 6-28 alkyl glycidyl ether, C 6-28Glycidyl fatty acid esters, C 6-28 alkylphenol glycidyl ethers, etc.

[0121] In some embodiments, the epoxy resin is novolac epoxy resin EEW 200, novolac epoxy resin EEW 300, or novolac epoxy resin EEW 140.

[0122] In some embodiments, the epoxy resin is a compound represented by the following formula:

[0123]

[0124] where n is 0, 1, 2, 3, 4, or 5, and m is 0, 1, 2, 3, 4, or 5.

[0125] In some embodiments, the epoxy resin is included in an amount of about 1 wt% to about 30 wt%. In some embodiments, the epoxy resin is included in an amount of about 1 wt% to about 25 wt%. In some embodiments, the epoxy resin is included in an amount of about 1 wt% to about 20 wt%. In some embodiments, the epoxy resin is included in an amount of about 1 wt% to about 15 wt%. In some embodiments, the epoxy resin is included in an amount of about 3 wt% to about 15 wt%. In some embodiments, the epoxy resin is included in an amount of about 1 wt% to about 5 wt%. In some embodiments, the epoxy resin is included in an amount of about 5 wt% to about 20 wt%. In some embodiments, the epoxy resin is included in an amount of about 5 wt% to about 15 wt%. In some embodiments, the epoxy resin is included in an amount of about 10 wt% to about 20 wt%. In some embodiments, the epoxy resin is included in an amount of about 15 wt% to about 30 wt%. In some embodiments, the epoxy resin is included in an amount of about 15 wt% to about 25 wt%. In some embodiments, the epoxy resin is included in an amount of about 10 wt% to about 15 wt%. In some embodiments, the epoxy resin is included in an amount of about 10 wt%, about 11 wt%, about 12 wt%, about 13 wt%, about 14 wt%, about 15 wt%, about 16 wt%, about 17 wt%, about 18 wt%, about 19 wt%, about 20 wt%, about 21 wt%, about 22 wt%, about 23 wt%, about 24 wt%, about 25 wt%, about 26 wt%, about 27 wt%, about 28 wt%, about 29 wt%, or about 30 wt%.

[0126] Desirably, resin (a) is present in a weight ratio of (a)(i):(a)(ii) of about 0.3:1 to about 6:1.

[0127] As described above, the compositions of the present disclosure comprise, inter alia, core-shell rubber in addition to other components. Rubber particles having a core-shell structure are additional components of the compositions of the present invention. Such particles generally have a core comprising a polymeric material having elastomeric or rubber-like properties (i.e., a glass transition temperature of less than about 0 °C, such as less than about -30 °C), the core being surrounded by a shell comprising a non-elastomeric polymeric material (i.e., a thermoplastic or thermosetting / crosslinked polymer having a glass transition temperature greater than ambient temperature, such as greater than about 50 °C).

[0128] For example, the core may comprise a diene homopolymer or copolymer (e.g., a homopolymer of butadiene or isoprene, a copolymer of butadiene or isoprene with one or more ethylenically unsaturated monomers such as vinyl aromatic monomers, (meth)acrylonitrile or (meth)acrylate, etc.); while the shell may comprise a polymer or copolymer of one or more monomers having a suitably high glass transition temperature, where the monomers are, for example, (meth)acrylates (e.g., methyl methacrylate), vinyl aromatic monomers (e.g., styrene), vinyl cyanides (e.g., acrylonitrile), unsaturated acids and anhydrides (e.g., acrylic acid), (meth)acrylamides, etc. Other rubbery polymers may also be suitably used for the core, including polybutyl acrylate or polysiloxane elastomers (e.g., polydimethylsiloxane, especially crosslinked polydimethylsiloxane). The rubber particles may comprise more than two layers (e.g., a central core of one rubbery material may be surrounded by a second core of a different rubbery material, or the rubbery core may be surrounded by two shells of different composition, or the rubber particles may have a structure of soft core, hard shell, soft shell, hard shell). In one embodiment of the present invention, the rubber particles used comprise a core and at least two concentric shells having different chemical compositions and / or properties. The core or the shell or both the core and the shell may be crosslinked (e.g., ionically crosslinked or covalently crosslinked). The shell may be grafted to the core. The polymer constituting the shell may carry one or more different types of functional groups (e.g., epoxy groups) capable of interacting with other components of the compositions of the present invention.

[0129] Typically, the core accounts for 50 to 95 wt% of the rubber particles, while the shell accounts for 5 to 50 wt% of the rubber particles.

[0130] The core-shell rubber particles are of nanoscale dimensions. That is, the average diameter of the rubber particles is less than 500 nm, such as less than 200 nm, desirably in the range of 25 to 100 nm.

[0131] Methods for preparing rubber particles having a core-shell structure are well known in the art and are described, for example, in U.S. Patent Nos. 4,419,496, 4,778,851, 5,981,659, 6,111,015, 6,147,142, and 6,180,693.

[0132] Rubber particles having a core - shell structure can be prepared as masterbatches in which the rubber particles are dispersed in one or more epoxy resins (such as the diglycidyl ether of bisphenol A). For example, the rubber particles are typically prepared as an aqueous dispersion or emulsion. Such a dispersion or emulsion can be combined with the desired epoxy resin or mixture of epoxy resins, and water and other volatile substances are removed by distillation or the like. One method of preparing such masterbatches is described in more detail in International Patent Publication No. WO2004 / 108825. For example, an aqueous latex of rubber particles can be contacted with an organic medium having partial solubility in water, and then with another organic medium having a lower partial solubility in water than the first organic medium to separate the water and provide a dispersion of the rubber particles in the second organic medium. This dispersion can then be mixed with the desired one or more epoxy resins and the volatile substances removed by distillation or the like to provide the masterbatch.

[0133] Particularly suitable dispersions of rubber particles having a core - shell structure in an epoxy resin matrix are available from Kaneka Corporation, such as KANEKA MX - 120 (a masterbatch of 25 wt% nano - scale core - shell rubber in a diglycidyl ether of bisphenol A matrix) and KANEKA MX - 156.

[0134] For example, the core can be formed mainly from polybutadiene, polyacrylate, polybutadiene / acrylonitrile mixtures, polyols, and / or polysiloxanes or any other monomer feedstock that gives a low glass transition temperature.

[0135] The shell can be formed mainly from polymethyl methacrylate, polystyrene, or polyvinyl chloride or any other monomer feedstock that gives a higher glass transition temperature.

[0136] The core - shell rubber prepared in this way can be dispersed in an epoxy matrix or a phenolic matrix. Examples of epoxy matrices include: diglycidyl ethers of bisphenol A, F, or S, or bisphenols, novolac epoxy resins, epoxidized nitrogenous based amines, and alicyclic epoxy resins. Examples of phenolic resins include phenoxy based on bisphenol A.

[0137] The core - shell rubber can be dispersed in the epoxy or phenolic matrix in an amount of 5 to 50 wt%, with 15 to 25 wt% being desired.

[0138] In the higher range of such core - shell rubber content, an increase in viscosity can be observed in the dispersion in a relatively short period of time, and agglomeration, sedimentation, and gelation can also be observed in the dispersion.

[0139] In the formulations of the present invention, the use of these core-shell rubbers enables toughening to occur upon curing of the formulation, regardless of the temperature used to cure the formulation. That is, due to the inherent two-phase separation in the formulation caused by the core-shell rubber, there is a minimal disruption of the matrix properties — in contrast to, for example, liquid rubbers that are miscible or partially miscible in the formulation and can be cured at temperatures different from those used to cure the formulation — because the two-phase separation in the formulation is often observed to be substantially uniform in nature.

[0140] It is believed that many of the core-shell rubbers commercially available from Kaneka have a core prepared from (meth)acrylate-butadiene-styrene copolymers, where butadiene is the major component in the phase-separated particles dispersed in the epoxy resin. Other commercially available masterbatches of core-shell rubber particles dispersed in epoxy resins include GENIOPERL M23A (a dispersion of 30 wt% core-shell particles in an aromatic epoxy resin based on bisphenol A diglycidyl ether; the core-shell particles have an average diameter of about 100 nm and comprise a crosslinked silicone elastomer core onto which an epoxy-functionalized acrylate copolymer has been grafted); the silicone elastomer core accounts for about 65 wt% of the core-shell particles), which is available from Wacker Chemie GmbH, Germany.

[0141] Include core-shell rubbers that themselves comprise a polymer core and at least two polymer layers surrounding the core, where each layer has a different polymer composition from the other layers, and where at least one polymer layer comprises a polymer that is a gradient polymer, the gradient polymer being a copolymer composed of at least two different monomers (A) and (B) and having a repeating unit gradient from mainly monomer (A) along the copolymer to mainly monomer (B); and where, when mixed together, a peroxide catalyst initiates the curing of the free-radical curable components and a transition metal initiates the curing of the cyanoacrylate components.

[0142] The core-shell rubber should comprise particles having a particle size of 170 to 350 nm and a pH of 6 to 7.5, which comprise: a polymer rubber core comprising at least partially crosslinked isoprene or butadiene and optionally present styrene, and at least two polymer layers, where at least one polymer layer is an outermost thermoplastic shell layer having a Tg greater than 25 °C, and each layer has a different polymer composition.

[0143] The core-shell rubber should comprise a polymer rubber core surrounded by a polymer layer, which is a polymer core layer having a glass transition temperature below 0 °C and a polymer composition different from that of the polymer rubber core, wherein the polymer core layer is a gradient zone. Desirably, the core-shell rubber should comprise at least one polymer core layer and at least two polymer shell layers, wherein the polymer core layer has a composition different from that of the polymer shell layers, wherein each shell layer has a polymer composition different from that of the other shell layers, and wherein at least one polymer shell layer is a gradient zone.

[0144] The core-shell rubber should comprise a polymer rubber core having a glass transition temperature less than 0 °C, for example less than about -10 °C, desirably less than about -20 °C, and advantageously less than about -25 °C, and most advantageously less than about -40 °C, for example from about -80 °C to about -40 °C.

[0145] The core-shell rubber should comprise a polymer rubber core composed of any one or more of isoprene homopolymer, butadiene homopolymer, isoprene-butadiene copolymer, copolymer of isoprene and up to 98 wt% vinyl monomer, and copolymer of butadiene and up to 98 wt% vinyl monomer. The vinyl monomer can be styrene, alkylstyrene, acrylonitrile, (meth)acrylic acid alkyl ester, or butadiene or isoprene. Desirably, the core should be composed of one of polybutadiene, copolymer of butadiene and styrene, or terpolymer of methyl methacrylate, butadiene and styrene.

[0146] In some embodiments, the core can also be covered by a core layer. The core layer means that the glass transition temperature (Tg) of the polymer composition of the core layer is less than 0 °C, for example less than about -10 °C, desirably less than about -20 °C, and advantageously less than about -25 °C. Desirably, the core layer is a gradient polymer.

[0147] The core-shell rubber should have more than one shell and desirably two shells. The Tg of the outer shell in contact with at least the thermoplastic matrix is greater than about 25 °C, for example greater than about 50 °C.

[0148] One or more shells of the core-shell rubber can be composed of one or more of the following: styrene homopolymer, alkylstyrene homopolymer, or methyl methacrylate homopolymer, or a copolymer comprising at least 70 wt% of one of the above monomers and at least one comonomer selected from the other above monomers, another (meth)acrylic acid alkyl ester, vinyl acetate, and acrylonitrile. The shell can be functionalized, for example, with an acid anhydride of an unsaturated carboxylic acid, an unsaturated carboxylic acid, and an unsaturated epoxide (such as maleic anhydride, glycidyl methacrylate), 2-hydroxyethyl methacrylate, and alkyl (meth)acrylamide.

[0149] Gradient copolymers are produced by occupying the position between two layers and, in so doing, create a gradient region where one side is richer in monomers / polymers from the adjacent layer and the other side is richer in different monomers / polymers that form the next layer. The gradient region between the core and the shell or between two polymer shells can be prepared, for example, by monomers having different copolymerization parameters or by reacting in a semi - continuous mode under fed - batch conditions where the addition rate of the monomers is slower than the reaction rate. However, the gradient polymer is never the outermost layer of the core - shell particles.

[0150] The monomers used to form the gradient polymer are selected from the monomers mentioned together with the core and the corresponding shell according to the function of the adjacent layer.

[0151] The Young's modulus of the polymeric rubber core is always less than that of the other polymer layers. The Young's modulus of the layer containing the gradient polymer is always less than that of the outermost layer.

[0152] The core - shell rubber should be in the form of fine particles having a rubber core and at least one thermoplastic shell, where the particle size is generally less than 1 μm, advantageously 50 nm to 500 nm, preferably 100 nm to 400 nm, most preferably 150 nm to 350 nm, advantageously 170 nm to 350 nm.

[0153] The core - shell rubber can be prepared by emulsion polymerization. For example, a suitable method is the two - stage polymerization technique where the core and the shell are prepared in two sequential emulsion polymerization stages. If there are more shells, then another emulsion polymerization stage follows. The graft copolymer is obtained by graft - polymerizing at least monomers or monomer mixtures containing aromatic vinyl, alkyl methacrylate or alkyl acrylate in the presence of a latex containing a butadiene - based rubber polymer. Commercially available examples of such core - shell rubbers can be obtained from Arkema Inc., Cary, NC under the trade name CLEARSTRENGTH. Arkema describes CLEARSTRENGTH XT100 as, for example, a methyl methacrylate - butadiene - styrene core - shell toughener that is compatible with various monomers and is easily dispersed in most liquid resin systems and shows a limited effect on their viscosity while providing a toughening effect over a wide working temperature range.

[0154] Generally, the core accounts for about 50 to about 95 wt% of the rubber particles, while the shell accounts for about 5 to about 50 wt% of the rubber particles.

[0155] Preferably, the size of the rubber particles is relatively small. For example, the average particle size can be about 0.03 to about 2 microns or about 0.05 to about 1 micron. The rubber particles can have an average diameter of less than about 500 nm, such as less than about 200 nm. For example, the core - shell rubber particles can have an average diameter in the range of about 25 to about 200 nm.

[0156] These core-shell rubbers enable toughening to occur in the composition and often in a predictable manner (in terms of temperature neutrality towards curing) due to substantially uniform dispersion, which is typically observed in commercially available core-shell rubbers.

[0157] The rubber particles can be used in dry form or can be dispersed in the matrix as described above.

[0158] Combinations of different rubber particles can be advantageously used in the present invention. The rubber particles can differ, for example, in particle size, the glass transition temperature of their respective materials, whether the materials are functionalized, the degree of functionalization and what they are functionalized with, and whether and how their surfaces are treated.

[0159] Based on the total weight of the composition, the amount of core-shell rubber present should be from about 1 to about 50 wt%, such as from about 5 to about 30 wt%, desirably from about 10 to about 20 wt%.

[0160] The core-shell particles (b) should desirably be present in a weight ratio to the resin (a) of from about 0.15:1 to about 0.95:1.

[0161] The composition of the present invention can also contain an inorganic filler, such as silica.

[0162] For example, when present, the inorganic filler can be silica in the form of fumed silica, fused silica, surface-activated silica, and any of which are nanoscale. The silica nanoparticles can be pre-dispersed in the epoxy resin and can be selected from those commercially available from Hanse Chemie, Germany under the trade name NANOPOX (e.g., NANOPOX XP 0314, XP 0516, XP 0525). These NANOPOX-brand products are dispersions of silica nanoparticles in epoxy resin with a content not higher than about 50 wt%. It is believed that these NANOPOX-brand products have a particle size of from about 5 nm to about 80 nm. The manufacturer reports that NANOPOX XP 0314 contains 40 wt% of silica particles with a diameter of less than 50 nm in an alicyclic epoxy resin.

[0163] In some embodiments, the inorganic filler is a non-conductive filler, such as silica, as described above. In some embodiments, the filler is (or comprises) silica, calcium silicate, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, aluminum oxide (Al2O3), zinc oxide (ZnO), magnesium oxide (MgO), aluminum nitride (AlN), boron nitride (BN), carbon nanotubes, diamond, clay, aluminosilicate, etc., and mixtures of any two or more thereof.

[0164] In some embodiments, the inorganic filler is an inorganic non-conductive filler comprising particles having a maximum particle size of 5 μm or less than 5 μm. For example, in some embodiments, the filler has a particle size of from about 0.1 μm to about 5 μm or 0.1 μm to 5 μm.

[0165] In some embodiments, the inorganic filler is included in an amount greater than 0 wt%, such as from about 10 wt% to about 70 wt%, such as up to about 40 wt%, desirably up to about 25 wt%.

[0166] The inorganic filler (c) should desirably be present in a weight ratio to the resin (a) of from about 0.15:1 to about 0.95:1, i.e., (c):(a).

[0167] The inorganic filler (c) should also desirably be present in a weight ratio to the core-shell particles (b) of from about 0.95:1 to about 5:1, i.e., (c):(b).

[0168] The composition further comprises a curing agent package. Desirably, the curing agent package comprises a combination of the following:

[0169]

[0170] wherein each of R1, R2, R3, and R4 is independently selected from H, alkyl having 1 to 4 carbon atoms, alkoxy having 2 to 5 carbon atoms, and hydroxyalkyl having 1 to 4 carbon atoms,

[0171]

[0172] wherein each of R1, R2, R3, and R4 is independently selected from H, alkyl having 1 to 4 carbon atoms, alkoxy having 2 to 5 carbon atoms, and hydroxyalkyl having 1 to 4 carbon atoms, and

[0173]

[0174] Wherein herein R1, R2, R3, R4, R5 and R6 are each independently selected from H, alkyl having 1 to 4 carbon atoms, alkoxy having 2 to 5 carbon atoms, and hydroxyalkyl having 1 to 4 carbon atoms, and each of R2 and R3 and each of R5 and R6 together independently form a cyclic ring of 3 to 7 atoms with each other.

[0175] Desirably, the curing agent package (d) comprises an aromatic urea, 4,4-diaminodiphenyl sulfone, and dicyandiamide, including

[0176]

[0177] and

[0178]

[0179] The curing agent package should be used in the composition in an amount of about 7.0 wt% to about 10 wt%.

[0180] The ratio of the three components of the curing agent package can be about 35 parts: 100 parts: 10 parts to about 40 parts: 135 parts: 15 parts.

[0181] The curing agent package (d) should be present in a weight ratio to the resin (a) of about 0.2:1 to about 0.35:1.

[0182] In some embodiments, after the composition forms a film, the film has certain characteristics and / or properties such that the film is suitable for use in a thermocompression bonding process. For example, in some aspects, the composition exhibits at least the following physical properties after being B-staged to a film:

[0183] The DSC has an onset temperature of 160 °C to 180 °C,

[0184] The DSC has a peak temperature of 180 °C to 210 °C, and

[0185] The heat of reaction > 30 J / g.

[0186] In some aspects, the composition exhibits the following physical property after being B-staged to a film: when laminated to a 7 mm × 7 mm chip, after exposure to a temperature of about 175 °C for a period of about 1 hour, measuring the chip shows a warp of less than about 100 μm.

[0187] In some aspects, the composition exhibits at least the following physical properties after being B-staged to a film: when laminated to a metal lead frame or BT substrate on a 3 mm × mm chip, after exposure to a temperature of about 175 °C for a period of about 4 hours, the film adheres to the metal lead frame, showing an adhesion force of at least 3 kgf per chip.

[0188] In some aspects, the composition exhibits at least the following physical properties after being B-staged into a film:

[0189] DMA (Dynamic Mechanical Analysis), which shows a storage modulus < 2500 MPa at 25 °C, and

[0190] a glass transition temperature Tg > 200 °C.

[0191] In some aspects, the composition exhibits at least the following physical properties after being B-staged into a film:

[0192] DMA (Dynamic Mechanical Analysis), which shows a storage modulus > 50 MPa at 100 °C, and

[0193] a glass transition temperature Tg > 200 °C.

[0194] In some aspects, the composition exhibits at least the following physical properties after being B-staged into a film:

[0195] DMA (Dynamic Mechanical Analysis), which shows a storage modulus > 20 MPa at 150 °C, and

[0196] a glass transition temperature Tg > 200 °C.

[0197] In some aspects, the composition exhibits at least the following physical properties after being B-staged into a film:

[0198] DMA (Dynamic Mechanical Analysis), which shows a storage modulus > 10 MPa at 200 °C, and

[0199] a glass transition temperature Tg > 200 °C.

[0200] In some aspects, after being applied to a metal lead frame and cured at a temperature of 260 °C, the composition shows the following die shear strengths: > 9 kgf / die on a copper metal lead frame and > 5 kgf / die on a silver metal lead frame.

[0201] In some embodiments, after the composition forms a cured film, the Tg of the cured film is >100 °C, >125 °C, >150 °C, >160 °C, >165 °C, >170 °C, >175 °C, >180 °C, >185 °C, >190 °C, >200 °C, >210 °C, >220 °C, >230 °C, >240 °C, >250 °C, >260 °C, >270 °C, >280 °C, >290 °C or >300 °C, each measured by dynamic mechanical analysis (DMA). In some embodiments, after the composition forms a cured film, the Tg of the cured film is from 100 °C to 110 °C, 110 °C to 120 °C, 120 °C to 130 °C, 130 °C to 140 °C, 140 °C to 150 °C, 150 °C to 160 °C, 160 °C to 170 °C, 170 °C to 180 °C, 180 °C to 190 °C, 190 °C to 200 °C, 200 °C to 210 °C, 210 °C to 220 °C, 220 °C to 230 °C, 230 °C to 240 °C, 240 °C to 250 °C, 250 °C to 260 °C, 260 °C to 270 °C, 270 °C to 280 °C, 280 °C to 290 °C, or 290 °C to 300 °C, each measured by DMA.

[0202] In some embodiments, after the composition forms a B-stage film, the storage modulus of the cured B-stage film at 25 °C is <2,500 MPa, <2,000 MPa, <1,500 MPa, <1000 MPa, <500 MPa, <250 MPa or <200 MPa.

[0203] In some embodiments, after the composition forms a B-stage film, the storage modulus of the cured B-stage film at 25 °C is: from <2,500 MPa, <2,000 MPa to <1,500 MPa, from <1,500 MPa to <1,000 MPa, from <1,000 MPa to <500 MPa, from <500 MPa to <250 MPa, or from <250 MPa to <200 MPa. In some embodiments, after the composition forms a B-stage film, the storage modulus of the cured B-stage film at 25 °C is: from <2,500 MPa to <200 MPa.

[0204] In some embodiments, after the composition forms a B-stage film, the storage modulus of the cured B-stage film at 100 °C is > 50 MPa, > 100 MPa, > 200 MPa, > 300 MPa, > 400 MPa, > 500 MPa, > 600 MPa, > 700 MPa, > 800 MPa, > 900 MPa, or > 1,000 MPa. In some embodiments, after the composition forms a B-stage film, the storage modulus of the cured B-stage film at 100 °C ranges from 50 MPa to 200 MPa, 200 MPa to 300 MPa, from 300 MPa to 400 MPa, from 400 MPa to 500 MPa, from 500 MPa to 600 MPa, from 600 MPa to 700 MPa, from 700 MPa to 800 MPa, from 800 MPa to 900 MPa, or from 900 MPa to 1,000 MPa.

[0205] In some embodiments, after the composition forms a B-stage film, the storage modulus of the cured B-stage film at 150 °C is > 20 MPa, > 100 MPa, > 110 MPa, > 120 MPa, > 130 MPa, > 140 MPa, > 150 MPa, > 160 MPa, > 170 MPa, > 180 MPa, > 190 MPa, or > 200 MPa. In some embodiments, after the composition forms a B-stage film, the storage modulus of the cured B-stage film at 150 °C ranges from 20 MPa to 100 MPa, from 100 MPa to 120 MPa, 120 MPa to 130 MPa, from 130 MPa to 140 MPa, from 140 MPa to 150 MPa, from 150 MPa to 160 MPa, from 160 MPa to 170 MPa, from 170 MPa to 180 MPa, from 180 MPa to 190 MPa, or from 190 MPa to 200 MPa.

[0206] In some embodiments, after the composition forms a B-stage film, the storage modulus of the cured B-stage film at 200 °C is > 10 MPa, > 45 MPa, > 50 MPa, > 55 MPa, or > 60 MPa, > 65 MPa, > 70 MPa, > 75 MPa, > 80 MPa, > 85 MPa, > 90 MPa, > 95 MPa, or > 100 MPa. In some embodiments, after the composition forms a B-stage film, the cured B-stage film at 200 ℃The storage modulus below is from 10 MPa to 50 MPa, 50 MPa to 55 MPa, from 55 MPa to 60 MPa, from 60 MPa to 65 MPa, from 65 MPa to 70 MPa, from 70 MPa to 75 MPa, from 75 MPa to 80 MPa, from 80 MPa to 85 MPa, from 85 MPa to 90 MPa, from 90 MPa to 95 MPa, or from 95 MPa to 100 MPa.

[0207] In some embodiments, after the composition forms a B-stage film, the B-stage film has a minimum film melt viscosity of 10 Pa·s to 2000 Pa·s, as measured using a DHR2 rheometer in N2 at a ramp rate of 10 °C / min. In some embodiments, after the composition forms a B-stage film, the B-stage film has a minimum film melt viscosity of 20 Pa·s to 1800 Pa·s, as measured using a DHR2 rheometer in N2 at a ramp rate of 10 °C / min. In some embodiments, after the composition forms a B-stage film, the B-stage film has a minimum film melt viscosity of 30 Pa·s to 1500 Pa·s, as measured using a DHR2 rheometer in N2 at a ramp rate of 10 °C / min. In some embodiments, after the composition forms a B-stage film, the B-stage film has a minimum film melt viscosity of 50 Pa·s to 1200 Pa·s, as measured using a DHR2 rheometer in N2 at a ramp rate of 10 °C / min. In some embodiments, after the composition forms a B-stage film, the B-stage film has a minimum film melt viscosity of 100 Pa·s to 1000 Pa·s, as measured using a DHR2 rheometer in N2 at a ramp rate of 10 °C / min.

[0208] In some embodiments, after the composition forms a B-stage film, the B-stage film has a differential scanning calorimetry (“DSC”) onset temperature from 160 °C to 170 °C, from 170 °C to 180 °C, as measured by DSC in N2 at a ramp rate of 10 °C / min.

[0209] In some embodiments, after the composition forms a B-stage film, the DSC onset temperature of the B-stage film is from about 160 °C to about 170 °C, from about 170 °C to about 180 °C, from about 180 °C to about 190 °C, from about 190 °C to about 200 °C, from about 200 °C to about 210 °C, as measured by DSC in N2 at a ramp rate of 10 °C / min.

[0210] In some embodiments, the present disclosure refers to certain organic groups as "substituted". The term "substituted" means that the subject organic group bears one or more substituents, where a substituent is an atom or group of atoms that replaces a hydrogen atom on the subject organic group. In the case where an organic group is substituted, the substituent(s) can replace one or more hydrogen atoms, ranging from replacing exactly one hydrogen atom on the subject organic group to replacing all hydrogen atoms. In the case where an organic group can bear multiple substituents, the substituents are independently selected and can be, but need not be, the same.

[0211] In some embodiments, the present disclosure refers to certain organic groups as "unsubstituted". The term "unsubstituted" means that the subject organic group has no substituents (as defined by the term in the foregoing description).

[0212] The compositions of the present invention may also include co-reactants, curing agents, and / or catalysts. Examples include Lewis acids (such as phenols and their derivatives), strong acids (such as alkylenic acid), and cationic catalysts.

[0213] The compositions of the present invention further comprise an adhesion promoter and a film-forming agent.

[0214] As used herein, the term "adhesion promoter" refers to a compound that enhances the adhesion properties of the formulation into which it is incorporated. The adhesion promoter can be an organic or inorganic compound and can include combinations thereof. Non-limiting examples of adhesion promoters include organozirconate compounds, organotitanate compounds, and silane coupling agents. In some embodiments, the adhesion promoter is Z6040 from Dow Corporation, Midland, MI.

[0215] In some embodiments, the adhesion promoter is included in an amount of from about 1 wt% to about 5 wt%. In some embodiments, the adhesion promoter is included in an amount of from about 0.1 wt% to about 1.0 wt%. In some embodiments, the adhesion promoter is included in an amount of from about 0.5 wt% to about 1.0 wt%. In some embodiments, the adhesion promoter is included in an amount of from about 0.5 wt% to about 1.5 wt%. In some embodiments, the adhesion promoter is included in an amount of from about 1 wt% to about 2 wt%, from about 2 wt% to about 3 wt%, from about 3 wt% to about 4 wt%, or from about 4 wt% to about 5 wt%.

[0216] As used herein, the term "film-forming agent" refers to a compound that aids in forming a film, such as by increasing the viscosity of the combination material. Non-limiting examples of film-forming agents include elastomeric additive components such as, but not limited to: copolymer ethylene acrylic elastomers; natural or synthetic rubbers such as substituted polyethylene; resins such as polyvinyl butyral resin and chlorosulfonated polyethylene synthetic rubber (CSM); partially crosslinked butyl rubber compounds such as butyl rubber products commercially available from Royal Elastomers, New Jersey under the brand names KALAR, DPR, ISOLENE, and KALENE; and ethylene acrylic elastomeric materials such as VAMAC, which is commercially available from DuPont Corporation. Additional non-limiting examples of film-forming agents include, but are not limited to: acrylic polymers such as copolymers of butyl acrylate - ethyl acrylate - acetonitrile and copolymers of ethyl acrylate - acetonitrile (e.g., polymers containing glycidyl functional groups), commercially available examples of which include those from Nagase JP.

[0217] In some embodiments, the film-forming agent (or binder resin) is included in an amount of from about 1 wt% to about 25 wt%. In some embodiments, the binder resin is included in an amount of from about 1 wt% to about 20 wt%. In some embodiments, the binder resin is included in an amount of from about 10 wt% to about 20 wt%. In some embodiments, the binder resin is included in an amount of from about 13 wt% to about 18 wt%. In some embodiments, the binder resin is included in an amount of from about 14 wt% to about 16 wt%. In some embodiments, the binder resin is included in an amount of about 10 wt%, about 11 wt%, about 12 wt%, about 13 wt%, about 14 wt%, about 15 wt%, about 16 wt%, about 17 wt%, about 18 wt%, about 19 wt%, about 20 wt%, about 21 wt%, about 22 wt%, about 23 wt%, about 24 wt% or about 25 wt%.

[0218] Aspects of the present disclosure also relate to methods of preparing B-stage films and / or cured films.

[0219] In some embodiments, the method of preparing a cured film comprises:

[0220] providing a composition comprising:

[0221] two or more resins selected from: (i) maleimide-containing resins, nadicimide-containing resins, itacimide-containing resins, and (ii) epoxy resins,

[0222] core-shell particles,

[0223] optionally present inorganic fillers;

[0224] Curing Agent Packaging

[0225] Cast the composition into a film; and

[0226] Expose the cast film to an elevated temperature to cure the film.

[0227] In some embodiments of the method for preparing a cured film, two or more resins selected from maleimide-containing resins, nadicimide-containing resins, itaconicimide-containing resins, and epoxy resins are those disclosed elsewhere herein, and optionally in the amounts disclosed elsewhere herein.

[0228] In some embodiments of the method for preparing a cured film, core-shell rubbers are those disclosed elsewhere herein, and optionally present in the amounts disclosed elsewhere herein.

[0229] In some embodiments of the method for preparing a cured film, inorganic fillers are those disclosed elsewhere herein, and optionally, when present, in the amounts disclosed elsewhere herein.

[0230] In some embodiments of the method for preparing a cured film, one or more additives selected from adhesion promoters and film-forming agents are those disclosed elsewhere herein, and optionally present in the amounts disclosed elsewhere herein.

[0231] Example

[0232] Example 1

[0233] Sample Preparation

[0234] Prepare a screening formulation for identifying the curing agent packaging according to the present invention by combining the components listed in Table 1 below. It can be seen that the only variable in the components is the catalyst.

[0235] Table 1

[0236]

[0237] Catalyst 1 is 4,4-DDS (4,4-diaminodiphenyl sulfone); Catalyst 2 is a urea-type curing accelerator; Catalyst 3 is DICY (dicyandiamide).

[0238] Varnish Preparation

[0239] Cavitate the silica filler slurry in a suitable solvent for dispersion purposes. Weigh the required amount of the organic components and place them in the filler slurry container. Manually mix for about 5 minutes, then add enough additional solvent to obtain a solids content of 40 to 50% and a viscosity of 100 to 400 cps. Continue premixing with a high-speed mixer (about 1000 to 3000 rpm) for about 5 to 10 minutes. Filter the resulting varnish through a 10 μm filter to remove any oversize coarse resin or filler particles.

[0240] Film Preparation

[0241] Prepare film sheet samples by pouring the slurry onto a clean, prepared surface using a coater. Subsequently, heat the slurry in a retort furnace to produce a stable coating film that adheres well to the substrate (release liner). Then, apply a cover liner to the film to protect its surface under the desired film lamination heat and pressure.

[0242] DSC

[0243] For DSC analysis, subject a 10 mg film sample to a 10 °C / min temperature ramp from room temperature to 350 °C in an N2 atmosphere to collect data on the DSC onset temperature, peak temperature, and heat of reaction.

[0244] DMA

[0245] Perform DMA analysis of the tensile modulus of the film sample using a flat edge tensile film fixture on a TA Instruments, TA-Q800. The sample size is approximately (20 × 8 × 0.3 mm). Cure the sample by subjecting it to a 30-minute ramp from room temperature to 175 °C, then soaking at 175 °C for 1 hour.

[0246] Perform DMA from -70 °C to 300 °C at a ramp rate of 5.0 °C / min. The frequency is 10 Hz, and a strain amplitude of 5 microns is applied.

[0247] Reference Figure 3 The DMA graph is shown, where the cured film has a low room temperature modulus for low warpage and a high modulus at high temperatures - for example, 200 °C - to meet the wire bonding process requirements for small chip applications. And the DMA graph also shows an additional tanδ (T g , glass transition temperature) at a high temperature of 246.45 °C, indicating that the bismaleimide resin is cured into the epoxy resin network to improve the high temperature properties of the cured composition.

[0248] Chip Shear Strength

[0249] Laminate the film sample onto a silicon chip (3×3 mm), and then place the film sample onto substrates [Cu lead frame substrate, Ag lead frame substrate, Au-plated Cu (PPF) lead frame substrate, and BT substrate] with a force of 1 kg at 120 °C for 5 seconds using a chip bonder. Cure the component with a 30-minute ramp from room temperature to 175 °C, and then soak it at 175 °C for 4 hours. Test the HDSS (hot die shear strength) data of shearing the die at 260 °C. Test the HWDSS (hot and wet die shear strength) data of shearing the die at 260 °C and 85 °C / 85% RH after 24 hours. Repeat the HWDSS three times.

[0250] Evaluate the melt viscosity of the B-staged film in N₂ using a TA instrument, DHR2 rheometer at a ramp rate of 5 °C / min. The sample size is a thickness of approximately 550 μm and a diameter of 20 mm. Conduct various analyses on each formulation from Table 1 as described in the leftmost column. Summarize and present the results in Table 2 below.

[0251] Table 2

[0252]

[0253]

[0254] Referring to Table 2, screening sample 7 with an epoxy resin / bismaleimide (“BMI”) resin combination packaged with a three-part curing agent is shown, which shows higher adhesion to both metal lead frames and BT substrates than other screened samples. Screening sample 7 also shows a cured film with a low room temperature modulus for low warpage and a high modulus of 47 MPa at a high temperature of 200 °C. This combination of physical properties is particularly attractive for the wire bonding process requirements of small die applications. And the DMA data also shows a high tanδ (Tg, glass transition temperature) temperature > 200 °C, which indicates the presence of improved high temperature properties.

[0255] Example 2

[0256] Prepare the formulation according to the present invention by combining the components listed in Table 3 below.

[0257] Table 3

[0258]

[0259]

[0260] Silica filler 1 is a micron-sized silica filler with an average particle size < 0.5 μm; silica filler 2 is fumed silica.

[0261] Epoxy resin 1 is an alicyclic epoxy resin from Daicel.

[0262] BMI 1 is a phenylmethane maleimide oligomer; BMI 2 is a HOMIDE 802BMI resin; BMI 3 is a HOMIDE 400BMI resin. BMI 2 and BMI 3 are from Hos-Tec.

[0263] CSR1 is a PBd core-shell rubber in liquid BisA epoxy resin (40 wt%); CSR2 is a styrene-PBd copolymer core-shell rubber.

[0264] Catalyst 1 is 4,4-DDS (4,4-diaminodiphenyl sulfone); Catalyst 2 is a urea-type curing accelerator.

[0265] Catalyst 3 is DICY (dicyandiamide).

[0266] A variety of analyses were performed on each of the inventive samples in Table 3. The results are summarized and presented in Table 4 below. Additionally, for graphical representations of DMA refer to Figure 3 ; for graphical representations of DSC refer to Figure 4 ; and for graphical representations of melt viscosity refer to Figure 5 . A low melt viscosity is beneficial for the film to have good wetting properties for the substrate in the BGA encapsulated during the chip bonding step.

[0267] Table 4

[0268]

[0269]

[0270] The results show that the cured film material has a low room temperature modulus (<2500 MPa at 25 °C) for low warpage. And the DMA data also shows a high tanδ (Tg, glass transition temperature) temperature >200 °C, which indicates improved high temperature properties. Graphical representations can also be referred to Figure 3 and Figure 4 . Here, it can be seen that the film material has a DSC onset temperature in the range of 160 °C to 180 °C, a DSC peak temperature of 180 °C to 210 °C, and a heat of reaction >30 J / g.

[0271] The adhesion strength of each of the six inventive samples in Table 3 was also tested on 4 different substrates. Commercially available DDF1 is ATB100 and DDF2 is ATBF100E, both available from Henkel Corporation.

[0272] Adhesion data was simultaneously tested with the samples of the present invention under the same conditions to remove any artificial variations caused by different test conditions. The results of the evaluation of the thermal chip shear strength and the thermo-humid chip shear strength are summarized and presented in Table 5 below.

[0273] Table 5

[0274]

[0275]

[0276] The results show that these samples have higher adhesion to various metal lead frames and BT substrates after curing under thermal conditions and under thermal and humid conditions than the existing Henkel commercially available chip adhesive films.

Claims

1. A composition comprising: (a) Two or more resins selected from: (i) at least one of a maleimide-containing resin, a nadicimide-containing resin, or an itaconicimide-containing resin, and (ii) an epoxy resin; (b) Core-shell particles, wherein the core-shell particles comprise a polymer material having elastomeric properties or rubber-like properties surrounded by a shell containing a non-elastomeric polymer material; (c) Optionally present inorganic filler; (d) A curing agent package comprising wherein herein R1, R2, R3, and R4 are each independently selected from H, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 2 to 5 carbon atoms, and a hydroxyalkyl group having 1 to 4 carbon atoms, wherein herein R1, R2, R3, and R4 are each independently selected from H, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 2 to 5 carbon atoms, and a hydroxyalkyl group having 1 to 4 carbon atoms, and wherein herein R1, R2, R3, R4, R5, and R6 are each independently selected from H, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 2 to 5 carbon atoms, and a hydroxyalkyl group having 1 to 4 carbon atoms, and each of R2 and R3 and R5 and R6 together independently form a cyclic ring of 3 to 7 atoms; and (e) One or more additives selected from adhesion promoters and film formers.

2. The composition according to claim 1, wherein after the composition forms a B-staged film, the B-staged film has the following physical properties: DSC has an onset temperature of 160°C to 180°C, DSC has a peak temperature of 180°C to 210°C, and Heat of reaction > 30 J / g.

3. The composition according to claim 1, wherein after the composition forms a B-staged film, when the B-staged film is laminated onto a 7 mm × 7 mm chip and after a period of about 1 hour at a temperature of about 175°C, the chip is measured and shows a warpage of less than about 100 μm.

4. The composition according to claim 1, wherein after the composition forms a B-staged film, when the B-staged film is laminated onto a metal lead frame or a BT substrate of a 3 mm × 3 mm chip and after a period of about 4 hours at a temperature of about 175°C, the film adheres to the metal lead frame and shows an adhesion force of at least 3 kgf per chip.

5. The composition according to claim 1, wherein after the composition forms a B-staged film, the B-staged film shows the following properties: DMA (Dynamic Mechanical Analysis), which shows a storage modulus at 25°C < 2500 MPa, and Glass transition temperature Tg > 200°C.

6. The composition according to claim 1, wherein after the composition forms a B-staged film, the B-staged film shows the following properties: DMA (Dynamic Mechanical Analysis), which shows a storage modulus at 100°C > 50 MPa, and Glass transition temperature Tg > 200°C.

7. The composition according to claim 1, wherein after the composition forms a B-staged film, the B-staged film exhibits the following properties: DMA (Dynamic Mechanical Analysis), which shows a storage modulus > 20 MPa at 150 °C, and a glass transition temperature Tg > 200 °C.

8. The composition according to claim 1, wherein after the composition forms a B-staged film, the B-staged film exhibits the following properties: DMA (Dynamic Mechanical Analysis), which shows a storage modulus > 10 MPa at 200 °C, and a glass transition temperature Tg > 200 °C.

9. The composition according to claim 1, wherein after being applied to a metal lead frame and cured at a temperature of 260 °C, the composition exhibits the following die shear strengths: > 9 kgf / die on a copper metal lead frame and > 5 kgf / die on a silver metal lead frame.

10. The composition according to claim 1, wherein the maleimide-containing resin, nadicimide-containing resin, or itaconicimide-containing resin (a)(i) is present in an amount of about 5 wt% to about 25 wt%.

11. The composition according to claim 1, wherein the epoxy resin (a)(ii) is present in an amount of about 1 wt% to about 30 wt%.

12. The composition according to claim 1, wherein the resin (a) is present in a weight ratio of (a)(i):(a)(ii) of about 0.3:1 to about 6:

1.

13. The composition according to claim 1, wherein the core-shell particles (b) are present in an amount of about 5 wt% to about 30 wt%.

14. The composition according to claim 1, wherein the core-shell particles (b) are present in a weight ratio to the resin (a) of (b):(a) of about 0.15:1 to about 0.95:

1.

15. The composition according to claim 1, wherein the inorganic filler (c) is present in an amount greater than 0 wt% to about 40 wt%.

16. The composition according to claim 1, wherein the inorganic filler (c) is present in an amount greater than 0 wt% to about 25 wt%.

17. The composition according to claim 1, wherein the inorganic filler (c) is present in a weight ratio to the resin (a) of (c):(a) of about 0.15:1 to about 0.90:

1.

18. The composition according to claim 1, wherein the inorganic filler (c) is present in a weight ratio to the core-shell particles (b) of (c):(b) of about 0.95:1 to about 5:

1.

19. The composition according to claim 1, wherein the curing agent package (d) comprises an aromatic urea, 4,4-diaminodiphenyl sulfone, and dicyandiamide.

20. The composition according to claim 1, wherein the curing agent package (d) comprises an aromatic urea, 4,4-diaminodiphenyl sulfone, and dicyandiamide in a weight ratio of about 35 parts:100 parts:10 parts to about 40 parts:135 parts:15 parts.

21. The composition according to claim 1, wherein the curing agent package (d) is present in a weight ratio of (d):(a) of about 0.2:1 to about 0.35:1 with the resin (a).

22. The composition according to claim 1, wherein the curing agent package (d) comprises 23. The composition according to claim 1, wherein the maleimide-containing resin, nadimide-containing resin or itaconicimide-containing resin (a)(i) is selected from: wherein n is from 0 to 2 herein, wherein R is an alkyl group having 1 to 4 carbon atoms, a phenyl group or an alkylphenyl group having 7 to 11 carbon atoms, and n is from 1 to 12 herein, wherein R is an alkyl group having 1 to 4 carbon atoms or a phenyl group, X is a diarylalkylene, and n is from 1 to 2, wherein n is 0, 1, 2, 3, 4 or 5, or 24. The composition according to claim 1, wherein the epoxy resin (a)(ii) is selected from: wherein R is an alkyl group having 1 to 4 carbon atoms, and n is from 1 to 16 herein, and wherein X is an alkylene group having 1 to 4 carbon atoms, and n is from 0 to 75 herein.

25. A curing agent package, which comprises wherein R1, R2, R3 and R4 are each independently selected from H, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 2 to 5 carbon atoms and a hydroxyalkyl group having 1 to 4 carbon atoms, wherein R1, R2, R3 and R4 are each independently selected from H, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 2 to 5 carbon atoms and a hydroxyalkyl group having 1 to 4 carbon atoms, and wherein R1, R2, R3, R4, R5 and R6 are each independently selected from H, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 2 to 5 carbon atoms and a hydroxyalkyl group having 1 to 4 carbon atoms, and each of R2 and R3 and R5 and R6 together independently forms a cyclic ring of 3 to 7 atoms.

26. A curing agent package, which comprises

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