Competing Fracture of Thin-Chip Transferring From/Onto Prestrained Compliant Substrate

Abstract

The transferring of thin chip from donor to receptor plays a critical role in advanced electronic package, and the productivity is determined by the interfacial behavior between chip and substrate during chip transferring. The paper investigates analytical competing fracture model of chip–adhesive–substrate structure in thin-chip transferring (peeling-off and placing-on), to discover the critical process condition for distinguishing the interfacial delamination and chip crack. The structure is continuously subjected to ejecting needle, vacuum pick-up head, and wafer fixture, which leads to concentrated and distributed loads and dynamic boundary conditions. Additionally, two criterions based on competing fracture model are presented to determine the extreme chip dimension for peeling-off and the elimination of residual stress for placing-on. The theoretical results are validated by the finite-element simulation with virtual crack-closure technique (VCCT). This paper provides an insight for process optimization, to improve the success ratio and productivity of chip transferring.

Flexible electronics manufacturing technology and equipment

“…These undesired phenomena are induced by the force of the ejector pin, the relative movement of the pickup head, and the requirement for high-speed placement. Owing to the rapid growth of the flexible electronics market, Yin's research group at HUST proposed a competitive index quantitative evaluation method for chip peel ability [40][41][42]. The competitive behaviors of chip stripping and fracture and their influencing mechanisms were revealed.…”

“…The lateral vibration control of the substrate was achieved by applying transverse feedback control force on the substrate surface [105]. The research achievements have been successfully applied to chip peeling [42], thin-film heterostructure manufacturing [106], and fuel cell production [97]. Figure 12 shows a kind of R2R manufacturing equipment that combines the R2R process and flip chip technology.…”

Design of Stretchable Electronics Against Impact

“…(10) for a ¼ 0.5, E r /E i ¼ 0.1 and two representative values of t r /t P ¼ 0.01 and 0.1. Equation (19) clearly provides a simple but good estimate. Figures 3-5 show e versus the normalized thickness X in Eq.…”

“…5 e versus X for several values of t r /t P with E r /E i 5 0.1 and a 5 0.5 time t r $ 1 ls and duration of impact t P ¼ 10 ls, Eq. (19) gives X % 160 for the reduction of impact by ten times (i.e., e ¼ 0.1), which leads to a thickness $0.9 mm, a practical value for the encapsulation layer in stretchable electronics. This result suggests that Silbione may be a good candidate as the encapsulation layer of the stretchable electronics against impact.…”

“…In practical applications, several underlying mechanisms may reduce the reliability of flexible/ stretchable electronics, such as the mechanical fatigue due to long-term periodic activities of human muscles [11,12], or the electromigration in metallic interconnects at relatively high current densities [13,14]. In addition, it is inevitable that stretchable electronics will suffer from unexpected collisions or impacts when worn on the skin [15][16][17], leading to possible device failure such as the rupture of active silicon materials at high stress levels, the irreversible deformation of metallic interconnects under complex loading conditions, or the interfacial slippage and delamination due to stiffness mismatch [18][19][20][21][22]. Designs that minimize damage in such contexts are, therefore, important to consider.…”