OPTIMIZED STATIC AND DYNAMIC DRIVING FORCES FOR REMOVING FLUX RESIDUE UNDER FLUSH MOUNTED CHIP CAPS

摘要

Removal of flux residue under highly dense chip caps presents a difficult cleaning challenge. Chip caps are flush mounted to the circuit card. Upon reflow, flux residue fills the gap under the chip cap. Cleaning fluids must wet, dissolve, penetrate the flux dam, and flow under the component to adequately remove all flux residues. Increased board density, miniaturization, and Pb-free soldering magnify this problem. To address this problem, process parameters in the form of cleaning temperature, time, cleaning chemistry concentration, and impingement energy must be considered. This paper presents the results from a designed experiment of an advanced cleaning fluid combined with an optimized inline spray-cleaning machine for removing flux residue under flush mounted chip caps.