The electronics industry is moving towards finer and finer pitch devices. Current solder paste technology requires further development in this direction in order to be able to pursue this growing market. Companies are interested in using industry standard stencils for PCB manufacture 0.125 mm (0.005"), 0.15 mm (0.006") thickness. No-clean solder pastes (25 ― 45 micron powder particle size, class 3) that will print 0 25 mm diameter apertures at 0.5 mm pitch, through a 0.125 mm (0.005") or 0.15 mm (0.006") stencil are required to print both fine apertures and standard apertures in the same process. Solder paste release from a stainless steel or electroformed stencil and subsequent printed pad definition on a PCB is influenced by the chemical make-up of the soldering flux vehicle. A solder paste has to have a certain amount of 'tack' that allows for components to be placed, often at high speed without less. There is a critical balance whereby the tackiness, which holds a component often prevents good aperture release c f solder paste onto a PCB.
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