Investigation of reliability issues in high power laser diode bar packages

Rational Design of Soft–Hard Interfaces through Bioinspired Engineering

“…[ 17 ] These stress concentrations represent common sites of failure in a range of connections between engineering materials and are a particular challenge in the connection of composite materials to metals, in the development of electronics packaging, and the surgical reattachment of soft to hard tissues. [ 6–13,18 ]…”

“…[4,5] The fact that these interfaces fail so frequently is no surprise, as interfaces between engineering materials are common sites of failure throughout engineering. [6][7][8][9][10][11][12][13] When a compliant material contacts a stiff or rigid material, stress concentrations arise at their interface. [14,15] According to the linear theory of elasticity, such attachments can lead to stresses of infinite magnitude at certain free edges, a phenomenon known as a Williams free edge singularity for attachment to a rigid material [16] or a Bogy free edge singularity for attachment of two dissimilar materials.…”

“…[17] These stress concentrations represent common sites of failure in a range of connections between engineering materials and are a particular challenge in the connection of composite materials to metals, in the development of electronics packaging, and the surgical reattachment of soft to hard tissues. [6][7][8][9][10][11][12][13]18] Successful soft-hard interfaces in nature are thus a key focus for biomimetic schemes to attach dissimilar materials. Diversity of organisms need to attach to surfaces in aqueous environments, and a range of such schemes has been described from the cellular level (e.g., focal adhesions in cells and bacterial films) to the adhesion of entire multi-cellular organisms (e.g., attachment of barnacles and mussels).…”

Solid solution softening and enhanced ductility in concentrated FCC silver solid solution alloys

“…The lower yield strength is a very desirable material property in the applications associated with solid-state bonding. It allows the heterogeneous-bonded structure to curtail the thermal stresses, induced by coefficient of thermal expansion (CTE) mismatch [16], with an easier plastic deformation process, thereby preventing electronic devices from cracking and mechanical failures [17]. Therefore, solid solution softening is an attractive behavior in the utilization of heterogeneous structure integration when manufacturing the electronics.…”

Compound semiconductor bonded to AlN heat spreader substrate using graded intermediate layer

“…Large residual stresses are also responsible for the formation of defects in the semiconductor wafers, and these defects propagate into the device structures grown on the wafers. 21 Scattering of phonons by the defects further reduces the effective thermal conductivity of the composite layers. 19,20 In the absence of a graded intermediate layer and AlN, tensile stresses in the semiconductor and compressive stresses in the diamond, both parallel to the interface, will be generated upon cooling if the thickness of the compound semiconductor is smaller than that of AlN or diamond.…”