SMT007 Magazine

SMT-Apr2015

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56 SMT Magazine • April 2015 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 indus- try. Board designs that include advanced BGAs, CSPs with 0.4 mm and 0.3 mm pitch, as well as simpler 01005 and 008006 components, raise the bar for positioning demands and volume delivery for solder paste deposits. According to the iNEMI 2013 Roadmap, placement accuracy for these kinds of components will reach 6 sig- ma placement accuracy in X and Y of 30 µm by 2023 [3] . This level of placement accuracy for components must be accompanied by a relat- ed accuracy for the deposit of solder paste and related fluids. Among the alternatives for the deposition of solder paste and other fluids on a PCB is jetting, which offers advantages con- cerning precise volume repeatability, software control and local volume control (Figure 1). The ejection of fluid from a jetting head has been studied extensively for low-viscosity fluids. This research has naturally been driven by work related to inkjet printing [1] . The jetting of more complex fluids is challenging and the amount of research is limited. An interesting theoretical study on jetting in general was carried out by Clasen [3] . by Gustaf Mårtensson and Thomas Kurian Micronic MydaTa ab The goal of this study is to examine the ef- fect of piezo actuation profile on deposit quality with respect to positioning, shape and satellite levels in order to achieve adequate deposition quality for applications such as 0.4 mm BGA. Methods The jetting for this study was performed with a MY500 jet printer. The jetting mecha- nism is based on the increase of pressure in a Jetting Strategies for mBGAs: A Question of Give and Take FeAture

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