Abstract
Deformation measurements with a thermocouple were applied in a deformation test of solder joints. The thermocouple is effectively combined with a conventional testing machine. The lead–solder and non–lead solder joints were pulled and sheared. The load-displacement and electromotive force (Emf)–displacement curves can be continuously derived from the signals of a load cell and the thermocouple. The Emfs in tension were compared with that in shear. The maximum Emf value in tension was larger than the emf value in shear, which meant in weakness of the solder joint in shear. Fracture occurred at the interface between the copper layer pad and solder, and the obtained Emf is closely related to fracture at the interface. The maximum Emf value in the non-lead solder was smaller than the Emf value in the lead–solder.
Highlights
From an environmental viewpoint, lead containing solders are harmful to human beings and other living things, which is the reason lead–free solders and new technologies for electronic interconnections have been introduced
The strain energy change is caused by a deformation which has a small temperature change
This temperature change can be measured with a thermocouple; this presents a possible method for deformation measurements of small solder joints
Summary
Lead containing solders are harmful to human beings and other living things, which is the reason lead–free solders and new technologies for electronic interconnections have been introduced. Possible alternatives for lead-free solders include Sn-Ag-Cu and Sn-Zn materials. Deformation measurements of small and spherically shaped solder joints are difficult to make using conventional techniques. The strain energy change is caused by a deformation which has a small temperature change This temperature change can be measured with a thermocouple; this presents a possible method for deformation measurements of small solder joints. This paper describes the application of a thermocouple, i.e., an electromotive force technique, to the deformation measurements of small solder joints which are made of lead and lead free materials. This thermocouple technique was successively combined with a conventional testing machine. The tensile and shear tests were conducted and Emf data were measured during deformation of solder joints
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