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.
The paper describes the effect of the solder profile on the formation of an intermetallic layer in the solder composition of 57.6% Bi-42% Sn-0.4% Ag. Soldered joints were made by soldering of chip resistors of 1206 size with different soldering reflow profiles. Solder pads on the PCB are made of copper therefore they mainly make Cu 6 Sn 5 IMC. This layer has an effect on the mechanical strength of the soldered joint. Samples are measured by using the shear strength test. The thickness of the IMC layer is measured by Confocal Laser Scanning Microscope. IMC layer thickness grows with greater delivered energy into the joint during soldering.
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