Masters Theses

Keywords and Phrases

Solder shear strength

Abstract

"With growing concerns over environmental issues and recent legislation, the use of tin-lead solders is being rapidly replaced by lead-free (LF) solders. The rapid replacement of the tin-lead solders with lead-free solders has raised issues, particularly in the aerospace and defense industries, over the maintainability and repairability of electronic assemblies. Due to the long life cycle of these aerospace vehicles, repair and maintenance of electronic assemblies are critical in ensuring proper operation. An area that has lacked significant attention is repair, particularly hand repair using LF solders. This can result in a mixture of tin-lead (SnPb) and LF solders of various composition. In this study, SnPb, LF, and mixed solder joints were analyzed following thermally cycling and aging at 150°C to examine the composition and environmental effects on solder joints. Compositions of 0, 25, 50, 75, and 100 wt. % eutectic SnPb, with the balance consisting of a near eutectic Sn-Ag-Cu (SAC) solder with a composition of 96.5wt % Sn, 3.0wt % Ag, and 0.5wt% Cu, was used for the aging study. The studies have shown that the LF and mixed solder joints perform slightly worse during thermal cycling than SnPb solders, but have comparable if not superior shear strength properties for as-soldered joints compared to SnPb solder joints. After thermal cycling, the solder joint shear strength degraded for all compositions. However, there was no significant effect on the shear strength due to the aging time. The results of the aging study indicated that the SAC and mixed compositions outperformed the SnPb joints in terms of shear strength. It was also found that the type of flux has little effect on the shear strength of the as-soldered joints"--Abstract, page iv.

Advisor(s)

O'Keefe, Matthew

Committee Member(s)

Miller, F. Scott, 1956-
Fahrenholtz, William

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Metallurgical Engineering

Sponsor(s)

U.S. Air Force Research Laboratory (Wright-Patterson Air Force Base, Ohio)

Comments

The author would like to thank the Air Force Research Laboratory (AFRL) at Wright- Patterson AFB, OH, contract FA8650-04-C-704 for funding the project.

Publisher

University of Missouri--Rolla

Publication Date

Spring 2006

Journal article titles appearing in thesis/dissertation

  • Perspectives on repaired lead-free solder joints
  • Aging effects on mixed tin-lead and lead free (Sn/Ag/Cu) solder joints

Pagination

x, 39 pages

Note about bibliography

Includes bibliographical references.

Rights

© 2006 Richard Shigemichi Colfax, All rights reserved.

Document Type

Thesis - Restricted Access

File Type

text

Language

English

Subject Headings

Joints (Engineering)Lead-free electronics manufacturing processesSolder and soldering -- Testing

Thesis Number

T 8938

Print OCLC #

81252475

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