Structural integrity in electronics

Abstract

A B S T R A C T With continuing miniaturisation, increased performance demands and the requirement to remove lead from solder alloys, the challenges to structural integrity and reliability of electronic equipment are substantial and increasing. This paper outlines typical features in electronic equipment of which the structural integrity community may be generally unaware. Potential failure modes in service are described, and the problems of scale and material characteristics are considered. Progress in the application of fracture mechanics to the life prediction of interconnections is reviewed. The limited evidence available suggests that the crack growth resistance of silver-containing lead-free solders is superior to that of the traditional Sn-37Pb under cycle-controlled conditions but there is no difference when time-dependent conditions prevail. In several respects, it is contended that the electronics sector is faced with challenges at least equivalent to those encountered in gas turbines and nuclear power generation.

Railway fatigue failures: an overview of a long standing problem

“…The current requirements to remove lead from solder alloys adds to the pressures caused by continuing miniaturisation and increased performance demands. The problems of structural integrity and reliability of electronic equipment are thus substantial and increasing [26]. The scale of the problem can be judged from the estimated 10 13 soldered electronic interconnections manufactured annually, about 1600 for every person on earth!…”

Damage Produced in Solder Alloys during Thermal Cycling

“…Three potential components of damage to soldered joints under thermal cycling have been identified as intrinsic (inherent in the solder itself), contact (arising when dissimilar materials are joined together), and geometrical (arising from the arrangement of neighboring joints on a board). 18 Tin exists as b-tin having a body-centered-tetragonal structure with a = 0.58318 nm, c = 0.31818 nm, and a c/a ratio of 0.5456. 19 This structure exhibits significant anisotropy in its thermal and elastic properties, as listed in Table I.…”

Testing method for measuring corrosion resistance of surface mount chip resistors

“…Figure 1(a) shows a schematic cross section view of the main elements of a chip resistor [9,11]. The wraparound terminations generally comprise two layers: a solder layer on the outside (Sn); and a protective barrier (Ni) between the solder layer and ceramic substrate (Al 2 O 3 ).…”

“…Surface mount thick chip resistors are amongst the simplest and most inexpensive of all components used in packaging [8][9][10]. However, resistor failures in some systems are often responsible for complete functional breakdown [11][12][13][14][15][16].…”