Syntheses and characterizations of thermally degradable epoxy resins. III

Abstract

In flip-chip technology, the development of reworkable underfill materials has been one of the keys to the recovery of highly integrated and expensive board assembly designs through the replacement of defective chips. This article reports the syntheses, formulations, and characterizations of two new diepoxides, one containing secondary ester linkages and the other containing tertiary ester linkages, that are thermally degradable below 300°C. The secondary and tertiary ester diepoxides were synthesized in three and two steps, respectively. Both compounds were characterized with NMR and Fourier transform infrared spectroscopy and formulated into underfill materials with an anhydride as the hardener and an imidazole as the catalyst. A dual-epoxy system was also formulated containing the tertiary ester diepoxide and a conventional aliphatic diepoxide, 3,4-epoxy cyclohexyl methyl-3,4-epoxycyclohexyl carboxylate (ERL-4221E), with the same hardener and catalyst. The curing kinetics of the formulas were studied with differential scanning calorimetry (DSC). Thermal properties of cured samples were characterized with DSC, thermogravimetric analysis, and thermomechanical analysis. The dual-epoxy system showed a viscosity of 18.7 and 0.87 P at 25 and 100°C, respectively. The cured secondary, tertiary, and dual-epoxy formulas showed decomposition temperatures around 265, 190, and 220°C, glass-transition temperatures around 120 -140, 110 -157, and 140 -157°C, and coefficients of thermal expansion of 70, 72, and 64 ppm/°C below their glass-transition temperatures, respectively. The shear strength of the cured dual-epoxy system decreased quickly with aging at 230°C. The reworkability test showed that the removal of a chip underfilled with this material from the board was quite easy, and the residue on the board could be thoroughly removed with a mechanical brush without obvious damage to the solder mask. In summary, the synthesized tertiary epoxide can be used as a reworkable underfill for flip-chip applications.

Photo-degradation of Reworkable Resin: A Mechanical Study

“…Therefore, evaluation of the mechanical properties was very important in order to optimize the degradation conditions. However, there are few reports that focused on the mechanical properties of the degraded reworkable resins which are applicable as reworkable underfill materials in flip-chip technology [14] and the matrix of carbon fiber-reinforced plastics [15].…”

“…Reworkable resins [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], which are thermosets thermally or chemically degradable under a given condition, have been extensively studied as environmentally-friendly materials without damaging the underlying materials. Based on this point of view, we have developed a series of "reworkable" epoxy resins having tertiary ester linkages [5][6][7][8][9][10][11], sulfonate ester linkages [12], and hemiacetal ester linkages [13] as thermallycleavable units.…”

Adsorption of chromium (VI) from aqueous solutions by cellulose modified with β-CD and quaternary ammonium groups

“…The degradation of poly(GMA) occurs at 360 • C at first and completely at 435 • C [20]. The endothermic peak of DTA curve at 250 • C is due to the fusion of the Cell-g-GMA-␤-CDN + and epoxy groups grafted [21,22]. The units of d-glucose began to decompose into a lot of organic compounds in the temperature ranging from 300 • C to 450 • C [23].…”

Dynamic DSC curing kinetic study of epoxy resin of 1,3‐bis(4‐hydroxyphenyl) prop‐2‐en‐1‐one using aromatic diamines and phthalic anhydride

“…[1][2][3][4][5][6][7][8][9] Epoxy resins with improved physico-chemical properties such as good thermal stability, low dielectric constant and dissipation factor with low water absorption, low coefficient of thermal expansion, low internal stress, high mechanical strength and low modulus are very useful for advanced technological applications. [10][11][12][13] Most frequently aromatic diamines are used as curing agents for epoxy resins but bond strength lowers at higher temperatures. The use of modified aromatic diamines and aromatic diamines containing heterocyclic rings are reported in the literature for the improvement of thermal resistance of epoxy resins.…”