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Abstract

Research & Development in Material Science

Lead-Free Solder Pull-Off Stress Comparison of a Novel Bump Pull Method with Conventional Hot/Cold Bump Pull Methods

  • Open or CloseGregory A Turner and DML Meyer*

    Department of Mechanical Engineering, The University of Rhode Island, USA

    *Corresponding author: DML Meyer, Thermomechanics Laboratory, The University of Rhode Island, Kingston, RI 02881, USA

Submission: April 27, 2018;Published: July 02, 2018

DOI: 10.31031/RDMS.2018.06.000648

ISSN : 2576-8840
Volume6 Issue5

Abstract

A novel method for directly testing the adhesion strength of three lead-free solders was developed and compared with conventional methods. The Isotraction Bump Pull method utilizes a combination of favorable qualities of the Cold and Hot Bump Pull tests. Solder bumps were generated onto copper printed circuit board substrates using an in-house-fabricated solder bump-on-demand generator. The method uses polymer epoxy to encapsulate solder bumps under uniform tractions, and tested under tension for pull-off stresses. Maximum pull-off stresses for the novel method are: 18MPa (Sn-3.5Ag), 16MPa (SAC 305) and 22MPa (Sn-0.7Cu) and fall at the low end in the literature comparisons. It is suggested that since the copper substrates used in the current work were untreated, that the lower pull-off stress values resulted. Energy Dispersive X-Ray Spectrometry of the newly created faces after fracture shows that brittle fracture of the Intermetallic Compound layer was the mode of failure..

keywords Cold bump pull (CBP); Hot bump pull (HBP); Lead-free; Solder; Pull-off stress; Intermetallic Compound (IMC)

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