Ultrasonic processes soldering

Aqueous based cleaners of MFC Technology Removal of adhesives and solder paste Wide process window Non-flammable Rapid drying Residue-free drying Long bath life Agitation of the cleaner (spray, ultrasonic, spray under immersion, overflow) necessary... 

A process that has found widespread use in practice is semi-aqueous cleaning with ZESTRON FA. This cleaner was especially developed for removal of no-clean soldering fluxes in ultrasonic batch or spray under immersion cleaning systems. It is used in the cleaning bath, rinsed with demineralized water, and then dried with hot air (see scheme in Figure 14.8.13.). 

Defects are most often detected by visual inspection or automated optical inspection (AOI). Other means of nondestructive evaluation (NDE) include electrical testing, x-ray inspection, and ultrasonic inspection. The preferred NDE inspection technique for BGA and CSP solder joints is x-ray inspection. Automated x-ray inspection equipment is often placed directly into the assembly process line for circuit board products having a large number of area-array components. 

Ultrasonic soldering has also been applied as a batch or continuous mass reflow process. In these instances, the molten solder is ultrasonically agitated while the assembly to be soldered is immersed in it. Similar arrangements have been made for ultrasonically vibrating the part while dipping it in a molten bath or wave of solder. These mass processes are more common for non-electronic assembly. 

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