Syntheses and characterizations of thermally reworkable epoxy resins. Part I

Wang, Lejun; Wong, C.P.

doi:10.1002/(sici)1099-0518(19990801)37:15<2991::aid-pola32>3.0.co;2-v

Cited by 99 publications

(33 citation statements)

References 6 publications

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“…At these test temperatures listed above, the time for the 1b system to loss 10% of weight was 90, 24, 6, and 4 min, respectively. The suitable rework temperature and time that are safe to the board and surrounding components is believed around 250 C for 5 min [12]. Therefore the thermal degradation property of this dual-epoxy system meets this requirement.…”

Section: Thermal Propertiesmentioning

confidence: 91%

A Reworkable Epoxy Resin for Isotropically Conductive Adhesive

Wong

2004

IEEE Trans. Adv. Packag.

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Electrically conductive adhesive (ECA) is a promising alternative to the toxic eutectic tin-lead solder as an interconnect material. Typical ECAs use epoxy resin as their matrix, which has superior properties over other polymers, such as high adhesion, and low dielectric constant. However, once cured, it is not reworkable. In this study, a liquid diepoxide was designed and synthesized, and used in isotropically conductive adhesive (ICA) formulations. This diepoxide has a molecular structure able to thermally decompose at mild temperature that allows selective individual removal of the bad component without damaging the board and its surroundings. The characterizations including proton and carbon 13 nuclear magnetic resonance, infrared spectroscopy indicated the success of the synthesis. A dual-epoxy system containing this secondary diepoxide and an equivalent bisphenol-A diepoxide were formulated and cured with an anhydride hardener and an imidazole catalyst. Thermal analyses, such as differential scanning calorimetry, thermo-gravimetry analysis (TGA), thermo-mechanical analysis (TMA) and dynamic mechanical analysis (DMA) were employed for the curing kinetics, thermal degradation behavior, glass transition temperature, coefficient of thermal expansion (CTE), and mechanical modulus, respectively. The dual-epoxy system showed two exothermal curing peaks at 140 C and 180 C, respectively. The thermoset of this dual-epoxy system has a decomposition temperature around 234 C, a glass transition temperature around 80 to 90 C, and CTEs of 74 ppm/ C and 225 ppm/ C below and above its Tg, respectively. The rework test on a surface mount component bonded to copper surface showed this ECA can be easily and quickly removed from the copper surface. The bulk resistance and contact resistance of ICAs were measured before and during an accelerated aging process in a temperature/humidity chamber (85 C/85% RH). The ECA showed good bulk resistivity and contact resistance comparable to its control and a commercial ECA on gold and copper surface finishes.Index Terms-Coefficient of thermal expansion (CTE), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), electrically conductive adhesive (ECA), FT-IR, isotropically conductive adhesive (ICA), nuclear magnetic resonance (NMR), thermo-gravimetry analysis (TGA), glass transmission temperature (Tg), thermo-mechanical analysis (TMA).

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Section: Thermal Propertiesmentioning

confidence: 91%

A Reworkable Epoxy Resin for Isotropically Conductive Adhesive

Wong

2004

IEEE Trans. Adv. Packag.

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“…The broad applications of epoxy polymers are partly due to the possibility of structural variations based on different curing agents and curing conditions . Some characteristics associated with epoxy polymers are excellent adhesion, no cure by‐products, high static and impact strength, versatility, and low shrinkage on cure . Among the disadvantages of epoxy resin thermosets are the difficulties associated with their short‐term use, including replacement and lack of degradability for industry and biomedical applications .…”

Section: Introductionmentioning

confidence: 99%

“…Most research has focused on the first approach for making thermally or chemically degradable epoxy networks. Some examples of the first approach include thermally degradable epoxy networks containing cleavable carbonate, ester, and carbamate linkages, and chemically degradable epoxy networks containing labile disulfide, carbon–carbon double bonds, carbamate, and acetal linkages, which can be cleaved either oxidatively or via exposure to acid or base. Some examples of the second approach include chemically degradable epoxy networks containing labile acetal, ketals, and disulfide linkages, which degrade under acidic or reductive conditions.…”

Section: Introductionmentioning

confidence: 99%

Degradable epoxy resins based on bisphenol A diglycidyl ether and silyl ether amine curing agents

Bassampour

Budy

Son

2016

J of Applied Polymer Sci

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A series of silyl ether amine curing agents were synthesized by selective substitution reactions of chloroalkylsilanes or the transetherification of alkoxysilanes. Crosslinked networks were prepared by mixing a stoichiometric ratio of bisphenol A diglycidyl ether (D.E.R 331) with the amine curing agents. The networks were characterized by ATR-FTIR spectroscopy, TGA, DSC, and DMA. The onset of thermal degradation, glass transition temperatures, and storage moduli for the networks were 350 8C, 70-108 8C, and 5-25 MPa, respectively. The degradation behavior of the cured samples was monitored for 30 days in PBS, NaOH 5% (w/v), and HCl 5% (v/v) solutions and the degradation products were characterized by spectroscopic methods. The thermal, mechanical, and degradation studies indicated that crosslink density, T g , storage modulus, and the rate of degradation were affected by the functionality of the amine curing agents and the number of hydrolyzable silyl ether bonds present per mole of curing agent. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44620.

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“…Demand on the 'reworkable resins', which is decomposable after use, is increasing more and more with respect to environmental aspects [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Development of reworkable resins is one of the most promising technologies to contribute the solution of the environmental problems.…”

Section: Introductionmentioning

confidence: 99%

“…From this point of view, lots of attention have been paid to the synthesis and characterization of reworkable resins by many researchers. Especially, the application to the underfill on electronic chips was extensively studied [7,8,11]. We previously reported the photo-cross-linking systems having redissolution properties in solvents [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%