Melamine-graphene epoxy nanocomposite based die attach films for advanced 3D semiconductor packaging applications

With the ultra-fast development of personal portable electronic devices, it is important to explore new die attach film (DAF) materials in the limited mounting area and height in order to meet the requirements of a high packaging density and a high operating speed. Graphene-based epoxy nanocomposites are becoming one of the most promising candidates for the next generation of DAFs combining the ultra-high thermal conductivity of graphene, and ultra-strong adhesion of epoxy polymers. However, poor dispersion and weak interfacial connections, due to the overly smooth surface of graphene nanosheets, are still pressing issues that limit their industrial applications. Additionally, pristine graphene nanosheets have only a small effect on improving the glass transition temperature (T_g) of epoxy composites to meet the requirements of DAFs. In this work, melamine-functionalized graphene is synthesized by using a nondestructive ball milling process, which results in greater dispersion and enhancement of the interfacial connections between graphene and epoxy resins demonstrated by both experimental and simulation results. In particular, the aromatic triazine rings of melamine increase T_g in the cured resin, thus improving the thermal stability of DAFs. The melamine-graphene (M-G) epoxy nanocomposites synthesized have a high T_g of 172 °C and an out-of-plane thermal conductivity of 1.08 W m^-1 K^-1 at 10 wt% loading. This is 6.4 multiples higher than that of neat epoxy. Moreover, M-G epoxy nanocomposites exhibit superb thermal stability, an effective low coefficient of thermal expansion (CTE), low moisture adsorption, and a useful high electrical resistivity. In the DAF performance test, involving experimentation and modeling, the samples present a better cooling capability and heat dissipation. This supports the idea that our findings have potential to be applied in the next generation of DAFs for high-power and high-density 3D packaging.

Synthesis and characterization of new aromatic copoly(ether amide)s bearing 4-trifluoromethylphenyl-2,6-diphenylpyridyl moieties in the main chain

A series of new aromatic fluorinated copoly(ether amide)s containing 4-(4-trifluoromethylphenyl)-2,6-diphenylpyridyl moiety with high molecular weight were prepared by a low-temperature solution polycondensation of terephthaloyl chloride with 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine and 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene with various mole ratios of the two monomers ranged from 20/80 to 80/20. All polymers were amorphous and soluble in common organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide and tetrahydrofuran at room temperature or upon heating at 70oC, and could be solution cast into transparent, tough, and flexible films with tensile strengths of 66.9–80.2 MPa, tensile moduli of 1.84–2.03 GPa, and elongations at break of 11.8–20.7%. These new polyamides displayed good thermal stability with gradually increasing of glass temperatures of 259–285oC as an increase of the 4-(4-trifluoromethylphenyl)-2,6-diphenylpyridyl component, the temperature at 10% weight loss of 476–505oC, and the residue of 55–61% at 750oC in nitrogen. They also exhibited low dielectric constants of 3.11–3.38 (1 MHz), low moisture absorption in the range of 1.43–1.75%, and high transparency with an UV–vis absorption cut-off wavelength in the 350–368 nm range.

Design and synthesis of new s-triazine polymers and their application as nanoparticulate drug delivery systems

The feasibility ofs-triazine polyamides to fabricate celecoxib-loaded nanoparticles.

Synthesis of poly(amide-imide)s from new diacid monomers

Two new diacid monomers 4,4′-bis[5-(trimellitimido)napthyloxy]diphenyl sulfone and 4,4′-bis[5-(trimellitimido)napthyloxy]benzophenone were synthesized and characterized by spectroscopic analysis. A series of poly(amide-imide)s (PAIs) were prepared from these diacids and aromatic diamines through phosphorylation reaction. The structures of the PAIs were characterized by infrared and 1H-NMR. The PAIs were characterized by X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, electrical properties, solution viscosity and solubility test. The flexible linkages and pendant groups in the PAIs chain will disturb chain–chain packing and their effects on solubility, thermal stability and electrical properties were investigated. PAIs showed excellent thermal stability and good solubility. The dielectric constants of the PAIs were in the range 4.15–4.77. The PAIs have electrical insulation character and the film can be used in insulation of electrical items operating at elevated temperatures.

Synthesis of polyamides by energy-efficient ultrasonic-assisted direct polycondensation

Four polyamides were synthesized by novel ultrasonic irradiation at 50 °C. Direct polymerization of 2-(morpholino)-4,6-bis(phenoxy-3-carboxy)-s-triazine with different diamines was conducted using a condensing agent. Synthesized polyamides were characterized by particle size distribution, solubility, density, viscosity, Fourier transform infrared spectra, 1H-nuclear magnetic resonance, thermogravimetric analysis and accelerated degradation of polyamides. All polyamides were readily soluble in polar organic solvents like N-methylpyrrolidone, N, N-dimethylacetamide and N, N-dimethylformamide at room temperature. The polyamides had inherent viscosities in the range 0.532–0.643 dL g−1 in dimethyl formamide at room temperature (30 °C) and density 1.137–1.198 g cm−3. All the polyamides showed good thermal stability under N2 atmosphere. Under accelerated condition degradation of polyamide was not observed without altering the surface morphology.

Synthesis and characterization of new organosoluble aromatic polyamides and polyazomethines containing pendent pentadecyl chains

New aromatic polyamides and polyazomethines containing pendent pentadecyl chains were synthesized by polycondensation of pentadecylbenzene-1,3-diamine with (i) four commercially available aromatic diacids, viz., biphenyl-4,4′dicarboxylic acid, 4,4′-oxybisbenzoic acid, terephthalic acid and isophthalic acid, and (ii) dialdehydes, viz., terephthaldehyde, isophthaldehyde and a 50 : 50 mol% mixture of terephthaldehyde, and isophthaldehyde, respectively. Inherent viscosities of polyamides and polyazomethines were in the range 0.35–0.56 dL g−1 and 0.33–0.38 dL g−1, respectively, indicating the formation of medium molecular weight polymers. The presence of pendent pentadecyl chains in polyamides and polyazomethines led to an improvement in their solubility in organic solvents. Polyamides could be cast into flexible, transparent and tough films from their solution in N, N-dimethylacetamide while polyazomethines could be solution cast into transparent, flexible and stretchable films from their CHCl3 solution. 1H-NMR studies based on amide proton signals and azomethine proton signals indicated the presence of constitutional isomerism in the polyamides and polyazomethines. Wide-angle X-ray diffraction patterns exhibited broad halo indicating that the polymers were amorphous in nature. X-ray diffractograms also displayed sharp reflections in the small angle region (2 θ ≈ 3°) indicating the formation of layered structure arising from packing of flexible pentadecyl chains. The glass transition ( Tg) temperatures of polyamides were in the range 169–215 °C while Tg values for polyazomethines were in the range 16–55 °C. The temperature for the 10% weight loss of polyamides and polyazomethines were in the range 430–460 °C and 425–440 °C, respectively, in a nitrogen atmosphere, which indicated their good thermal stability. Polyazomethines were also characterized by UV-Vis and photoluminescence spectroscopy and optical band gap ( Eg) values, calculated according to the maximum of the UV absorption, were found to be in the range 2.82–3.10 eV.