Temperature-profile experiments with lead-free SAC305 solder paste
Standard parameters: peak temperature 230-250℃, melt time 30-90 s, preheat time 120-240 s.
Variable tests:
Raising peak temperature to 250℃ increased void rate from 20% to 22%;
Shortening melt time to 45 s cut void rate to 18%;
Nitrogen fill / stencil aperture optimization showed no significant void-rate improvement.
Conclusion: limits of the conventional process
Adjusting the profile alone cannot break the 20% void-rate ceiling; a vacuum environment is required to remove bubbles.
Data visualisation:
Plot peak temperature vs void rate and mark the critical point (lowest void rate at 235℃).
