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April 2015 • SMT Magazine 63 figure 8: The effect of various piezo actuation profiles on the evolution of deposit diameter, Ø, as a function of deposit number, n. be observed. Slight deviations in size for a num- ber of the droplets can be observed and would result in a poor shape factor. Summary The demands on volume delivery and po- sitioning accuracy for solder paste deposits are increasing as the size and complexity of circuits continue to develop in the electronics industry. This study attempts to understand the depen- dencies on piezo actuation pulse profile on jet- ting deposit quality, especially focused on posi- tioning, satellites and shape. The correlation of deposit diameter and positioning deviation as a function of piezo actuation profile shows that positioning error for deposits increase almost monotonically with decreasing droplet volume irrespective of the piezo actuation profile. The trends for shape and satellite levels are not as clear and demand further study. The insights figure 9: example of jetting deposits on 0.4 mm bga with 250 μm pad size. FeAture JETTiNG STraTEGiES FOr MBGaS: a QuESTiON OF GivE aND TaKE continues