Flip chip underfill flow characteristics and prediction

Analysis of capillary flows in non-uniform cross-sectional capillaries

“…The capillary flow is widely applied recently in many modern processes such as underfilling of flip chip [1][2][3][4][5], crystal growth, flows in micro-fluidics, and a variety of other fields. In the underfilling process, polymer encapsulant was used to fill the gap between the chip and substrate around the solder joints to improve the long-term reliability of flip chip interconnecting systems.…”

Capillary impregnation into cylinder banks

“…Polymer is filled to the gap between the chip and substrate around the solder joints by capillary flow. The filled materials relax the mismatch of the thermal properties of the chip and substrate, and thus reduce the thermal stresses imposed on the solder joint [2][3][4][5]. The underfilling must be carried out carefully to ensure good quality of wetting around the solder joints without any flaws such as voids and streaks.…”

“…Capillary penetration of liquid into structures has been studied extensively due to its applications in various fields such as soil science, petroleum, crystal growth, microfluidics, and flip chip underfilling [1][2][3][4][5]. Basic understanding of the dynamics of capillary wetting can be dated back to the early twentieth century [6][7][8].…”

Underfill process for two parallel plates and flip chip packaging

“…Numerous studies on the development and modeling of the non-Newtonian flip chip underfill process have been carried out. Several assumptions and models, such as the Hele-Shaw [1][2][3], Washburn [4], power law [5], cross viscosity [6], and CastroMacosko [7] models, have been utilized to describe underfill flow behavior.…”