Correlation analysis of wettability, intermetallic compound formation and PCB contamination

Abstract

Purpose -The purpose of this paper is to verify how solder joint properties correlate with soldering profile set-up. These characteristics act against each other. All observed properties may significantly affect the quality and reliability of solder joints. The purpose is also to design recommendations for manufacturers of electronic assemblies. Design/methodology/approach -The samples for experiment were reflowed by using a laboratory reflow oven. A LEXT laser confocal microscope was used for wetting angle and intermetallic compound (IMC) thickness measurement. The ionic contamination was measured by using a contaminometer. Findings -The appropriate choice of soldering profile is very important for the reliability of electronic assemblies. The higher temperatures or longer preheating and soldering times improve the wetting angle. Likewise, there is also the activation of all the fluxes. The result is low contamination with printed circuit boards (PCBs). On the other hand, we must not forget that higher temperatures and longer soldering time also affect the thickness of the IMC. The outer limits recommended by the manufacturer were selected for the soldering profile set-up. Even within these limits, it is possible to achieve an improvement in the wetting angle, an improvement in levels of PCB contamination and an increase in the thickness of the IMC. This paper presents the results achieved for solders Sn42Bi57.6Ag0.4, Sn96.5Ag3Cu0.5 and Sn97Ag3. Originality/value -The gained knowledge on the correlation between IMC thickness, solderability of PCB and PCB contamination caused by different soldering profile set-ups can help to prevent reliability problems because each of the named effects has a significant influence on reliability.

Shear Strength of Conductive Adhesive Joints on Rigid and Flexible Substrates Depending on Adhesive Quantity

“…These metallographic cross-sections can be scanned using a laser confocal microscope (LEXT) (eg [17]), a fluorescence microscope or an electron microscope. Metallographic cross-sections of samples were made for RPCB and FPCB Ag and for each adhesive (4 crosssections).…”

Effect of flux functional group for solder paste formulation towards soldering quality of SAC305/CNT/Cu

“…Basically, the IMC layer is a by-product of the metallurgical process where molten solder interacts with the substrate. Many factors contribute to the wetting properties of a solder and include the choice of material, such as solder alloy, surface finish and flux, soldering profile and operating conditions (Steiner et al, 2015). Previous researchers have reported that fluxes significantly affect the wetting, solderability and the microstructure of intermetallic compound formation (Mario et al, 2006;Huan et al, 2011;Dong et al, 2008).…”

Solder joint quality evaluation based on heating factor

“…Process of dissolution and diffusion of solder atoms to soldered metals (and vice versa) is happening during the soldering, and the layer of IMC is formed. Furthermore, the IMC is growing over time (Yoon et al , 2004) and more during the isothermal aging (Steiner et al , 2015). The IMC layer is necessary for good mechanical connection, but, on the other hand, a thicker layer can cause problems because the IMC has different properties than solder – it differs in coefficient of thermal expansion, is more brittle and is non-wetting (Leonida, 1989).…”