Capillary impregnation into cylinder banks

Dynamic flow measurements of capillary underfill through a bump array in flip chip package

“…Meanwhile, Young [9] derived a filling time model (called ''Young model" in this paper) by considering viscous resistance and variable capillary pressure on solder bump according to the position of flow meniscus. Fig.…”

“…Nevertheless, this model has a possibility to overestimate flow resistance of bumps due to the one dimensional assumption. Young and Yang [8] and Young [9] also proposed a prediction model by considering viscous drag of flow and capillary pressure, which changes according to flow meniscus position on bump surface. It seems superior to the others in view of physical description of the flow phenomena.…”

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.…”

Micro-PIV measurements of capillary underfill flows and effect of bump pitch on filling process

“…Since these models did not fit experimental data due to the flow resistance by solder bumps, Wan et al (2005Wan et al ( , 2008) proposed a modified model by assuming bump array as one dimensional channel with variable widths. Young and Yang (2002) and Young (2004) also proposed a prediction model by considering viscous drag through cylinder banks. When bump pitch size becomes smaller compared with gap height, the above analytical approaches have a limit in predicting the filling time accurately and more realistic models need to be developed by making use of the experimental data on dynamic flows of capillary meniscus through solder bumps.…”