Solderability of Materials and Electronic Components

The concept of solderability is rigorously defined, accompanied by the proposal of quantitative criteria for its assessment. A comprehensive categorization of solderable materials into three distinct groups-namely, easily solderable, moderately solderable, and unsolderable-is proposed based on solderability parameters. Practical recommendations are given for the effective deployment of solderability testing methodologies across a spectrum of materials and electronic components. Detailed expositions are offered on the methods employed in the evaluation of solderability, encompassing solder immersion, measurement of solder spreading area, and assessment of capillary penetration into gaps. Schematic representations of these evaluation techniques, alongside descriptions of the requisite apparatus for their implementation, are presented. Furthermore, tabulated data on the solder spreading factors for diverse categories of chemical and electroplated coatings, including hot tinning, are given. Prolonged storage may lead to the formation of oxide films on the surface of coatings, thereby deteriorating solderability. To enhance the quality of electroplated coatings, it is recommended to employ periodic currents in nonstationary electrolysis modes during the deposition of electroplated coatings.