Reflow of tiny 01005 capacitor/SAC305 solder joints in protective atmosphere

Abstract

Purpose This paper aims to study the influence of reflow atmosphere and placement accuracy on the solderability of 01005 capacitor/SAC305 solder joints. Design/methodology/approach The 01005 capacitors were mounted on OSP-coated pads, and the samples were fabricated in four different atmospheres, i.e. 200 ppm O2/N2, 1,000 ppm O2/N2, 3,000 ppm O2/N2 and air. After the reflow process, visual inspection and X-ray detection were carried out to examine the solder joint shapes and possible defects. Some of the samples fabricated in different conditions were cross-sectioned and the solder joint microstructures were analyzed. On the other hand, besides placing the components on their normal pad positions, a 50 per cent offset of the x-axis (long axis) or y-axis (short axis) was introduced into the chip mounter programs to evaluate the 01005 capacitor’s assembly sensitivity to placement accuracy. The process-induced defects were investigated. Findings Experimental results indicated that an N2-based protective atmosphere was necessary for 01005 type assembly, as it could obviously improve the 01005 solder joint quality, compared with the air condition. The protective atmosphere had little effect on the appearance, quality and microstructure of solder joints when the oxygen concentration was below 3,000 ppm. But a very low oxygen concentration could increase the risk of tombstoning defects for the assembly process. The N2-based protective atmosphere containing 1,000-2000 ppm O2 was acceptable and appropriate for the assembly of tiny components. Originality/value The results of this work provide a set of reflow process parameters and recommendations for 01005 size component assembly in manufacturing.

Numerical modelling of the delamination in multi-layered ceramic capacitor during the thermal reflow process

“…On the experimental approach, the effects of post-process parameters on crack propagation were studied by Park et al (2005) and Kang et al (2008). There are other experimental works that studied the reflow soldering process of surface-mounted ceramic capacitors (Seppälä et al , 2000; Jin Kim et al , 2007; Tao et al , 2017), but without emphasizing the issues of cracking and delamination. To date, there is only one study that numerically simulates the crack in MLCCs during the reflow process (Ahmar and Wiese, 2017).…”

An experimental study of carbonyl powder power inductor cracking during reflow process

“…Thermal shock test was carried out on Sn-37Pb solder paste to investigate the microstructure evolution of intermetallic compound layer and examine the effect of thermal shock on the mechanical properties of solder joints (Gan et al, 2019). N 2 -based protective atmosphere in the reflow oven was introduced for 01005-type SMD, as it would increase the solder joint strength and reduce the risk of cracking compared to air condition (Tao et al, 2017). The new method of real-time reflow profiling, monitoring and control has been proposed for different peak reflow temperatures.…”

Machine learning-based prediction of component self-alignment in vapour phase and infrared soldering

“…The soldering method includes, on one hand, the atmosphere. Tao et al (2017) showed the differences in selfalignment of 01005 size (400 Â 200 mm) capacitors if the atmosphere of the reflow oven is air or nitrogen. They found that a nitrogen-based reflow atmosphere containing 1,000-2,000 ppm oxygen is acceptable for the assembly of surface mounted devices (SMD) components.…”