Board-Level Drop Reliability Performance Before and After Thermal Cycling Aging

2007 ◽  
Author(s):  
John H. L. Pang ◽  
Luhua Xu
Keyword(s):  
Thermal Cycling ◽  
Crack Path ◽  
Void Formation ◽  
Lead Free ◽  
Joint Interface ◽  
Reliability Test ◽  
Before And After ◽  
Kirkendall Voids ◽  
Reliability Performance ◽  
Board Level

The combined sequential reliability test of thermal cycling aging followed by board level drop test for lead-free SnAgCu soldered assemblies were investigated. Interfacial IMCs, Kirkendall voids formation and interconnect failure mode are studied subject to TC aging. Kirkendall voids were observed with Ar+ sputtering etching. The failure sites and mechanism were examined and correlated with IMC and void formation. Significant decrease of drop life was observed for both SAC/ENIG and SAC/Cu-OSP assemblies after thermal cycling aging. Growth of Kirkendall voids and IMC significantly weakened the solder joint interface during TC aging. Drop impact crack path changed from the IMC to the IMC/Cu interface.

Ripening-assisted void formation in the matrix of lead-free solder joints during solid-state aging

2007 ◽  
Vol 22 (4) ◽  
pp. 826-830 ◽  
Author(s):  
J.W. Jang ◽  
J.K. Lin ◽  
D.R. Frear ◽  
T.Y. Lee ◽  
K.N. Tu
Keyword(s):  
Solid State ◽  
Solder Joints ◽  
Solder Matrix ◽  
Void Formation ◽  
Stress Generation ◽  
Lead Free ◽  
Joint Interface ◽  
Formation Mechanisms ◽  
Lead Free Solder ◽  
Free Solder

Void formation in lead-free solder joints, away from the joint interface, has been observed after solid-state aging. These voids are attached to intermetallic precipitates in the solder matrix, especially to those that are adjacent to the layered intermetallic at the joint interface. Two potential void formation mechanisms are discussed. The mechanism proposed to describe void formation is that a flux of vacancies is created due to volume contraction during solid-state reaction. The ripening process among the intermetallics also assists this process. Using the suggested mechanisms, the void size was estimated. This phenomenon differs from the classical Kirkendall void formation because it is a nonequilibrium state of void formation and stress generation.

scholarly journals Impedance Spectroscopy of Lead-Free Ferroelectric Coatings

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 221
Author(s):  
Mariya Aleksandrova ◽  
Ivailo Pandiev
Keyword(s):  
Composite Coatings ◽  
Electrical Circuit ◽  
Ferroelectric Materials ◽  
Piezoelectric Transducers ◽  
Lead Free ◽  
Electrical Behavior ◽  
Oxide Composite ◽  
Before And After ◽  
Frequency Dependences ◽  
Good Agreement

This paper presents impedance measurements of ferroelectric structures involving lead-free oxide and polymer-oxide composite coatings for sensing and energy harvesting applications. Three different ferroelectric materials grown by conventional microfabrication technologies on solid or flexible substrates are investigated for their basic resonant characteristics. Equivalent electrical circuit models are applied to all cases to explain the electrical behavior of the structures, according to the materials type and thickness. The analytical results show good agreement with the experiments carried out on a basic types of excited thin-film piezoelectric transducers. Additionally, temperature and frequency dependences of the dielectric permittivity and losses are measured for the polymer-oxide composite device in relation with the surface morphology before and after introduction of the polymer to the functional film.

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