Effect of post-reflow no-clean solder paste residue on electrical performance

An experiment was conducted to examine the effect of postreflow no-clean solder paste residue of near-end and far-end signal crosstalk due to changes in dielectric constant and leakage resistance in the circuit environment. Additionally, the effect of different frequency levels on postreflow residue was examined. The results suggest that postreflow residues affect the signal-to-noise ratio on circuit boards, depending on the chemistry, residue level, and dielectric properties of these pastes. Higher levels of residues may cause signal degradation on the transmission lines. The noise level on circuit boards increases significantly if a solder paste exhibits excessive residue. Increased crosstalk is believed to be caused by an increase in the dielectric constant (excessive postreflow residues) between two transmission lines. The effect of postreflow residue on circuit performances was more noticeable at frequencies greater than 1 MHz. >