Mixed-Mode Fracture Behavior of Silica Particulate Filled Epoxide Resin

Abstract

Silica particulate filled epoxide resins are used as encapsulant materials in semiconductor packaging. In the present paper, fracture behavior of the epoxide resin, containing 70 wt% silica particles, have been studied at room temperature and high temperature, that is, 250°C. The three-point and four-point bending tests were performed to obtain Mode I and mixed-mode fracture toughness, respectively. The specimen fractured in a brittle manner under room temperature conditions, and the results obeyed the maximum hoop stress criterion. On the other hand, the results at high temperature showed a relatively low dependency on Mode II stress intensity factors. Fracture surface were observed in a scanning laser microscope. Finite element analysis, taking into account the microstructure of the material, have been conducted in order to investigate the influence of temperature on mixed-mode fracture behavior. Local fracture criteria were considered for the silica particles and the epoxide resin. The material constants in criteria were estimated from the bending strength and the Mode I fracture toughness of the material. Good agreement between experimental and numerical results was obtained for the fracture boundary curves on the Mode I and Mode II stress intensity diagram.

The role of T‐stress in brittle fracture for linear elastic materials under mixed‐mode loading

“…For example, for mode I, K Ic (= K If ) varies from 0.9 to 1.1. Davenport and Smith, 17 , 18 and Kishimoto et al ., 19 reveal similar levels of scatter in their experimental results. Chao and Zhang, 12 reviewed earlier experimental results for mode I fracture of PMMA.…”

“…Since the early work of Williams and Ewing 7 and Ueda et al ., 8 mixed mode fracture of PMMA has been studied extensively. Irrespective of the scatter, experimental work by Kishimoto et al ., 19 Maccagno and Knott 20 and Richard, 21 using asymmetric four‐point bend specimens, 19 , 20 or edge‐cracked specimens 21 reveal reasonable agreement with the conventional MTS criterion.…”

“…The more recent work on brittle fracture of PMMA 17–22 has not referred to the role of the T ‐stress in mixed mode fracture. Maybe this is because the T ‐stress is difficult to evaluate for the specimen shapes studied.…”

Increased Toughness of Zirconium-Based Bulk Metallic Glasses Tested under Mixed Mode Conditions

“…The materials included in Figure 10 are both ductile (e.g., 2034 Al alloy, [17] A710 steel, [31] and 1090 steel, [32] ) and brittle (e.g., pearlitic steel, [33] polycrystalline tungsten, [13] PMMA, [14] and silica-particulate-filled epoxide resin [34] ). The significant increases in normalized fracture energy with increased mixed mode in both the fully amorphous Vitreloy I and partially crystallized Vitreloy 106 are clear when plotted in this manner.…”