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Development of ultra dense edge interconnects for die to die connections based on immersion solder bridging

Proceedings - Electronic Components and Technology Conference

Chu, Dahwey; Rohwer, Lauren E.

A high density 2-D integration process that involves linking multiple die along their edges using a linear array of solder bridges was explored. Solder bridging is a versatile approach that is compatible with a range of interconnect geometries and metallizations. We have demonstrated this approach using copper plated nodules that were fabricated on the surface of the die and extend beyond the edge of the die. These nodules were 25 microns (μm) thick with 10, 20, and 50 μm widths. The formation of solder bridges was accomplished using immersion soldering, where the entire part was dipped into a molten solder bath. Due to surface energy effects, the solder selectively wets and flows along all wettable metal surfaces to form a strong solder bond. The solder can even flow across gaps (15 microns). © 2012 IEEE.

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TYPE Conference YEAR 2012
ScopusOSTI

Self-activating and doped tantalate phosphors

Rohwer, Lauren E.; Nyman, M.

An ideal red phosphor for blue LEDs is one of the biggest challenges for the solid-state lighting industry. The appropriate phosphor material should have good adsorption and emission properties, good thermal and chemical stability, minimal thermal quenching, high quantum yield, and is preferably inexpensive and easy to fabricate. Tantalates possess many of these criteria, and lithium lanthanum tantalate materials warrant thorough investigation. In this study, we investigated red luminescence of two lithium lanthanum tantalates via three mechanisms: (1) Eu-doping, (2) Mn-doping and (3) self-activation of the tantalum polyhedra. Of these three mechanisms, Mn-doping proved to be the most promising. These materials exhibit two very broad adsorption peaks; one in the UV and one in the blue region of the spectrum; both can be exploited in LED applications. Furthermore, Mn-doping can be accomplished in two ways; ion-exchange and direct solid-state synthesis. One of the two lithium lanthanum tantalate phases investigated proved to be a superior host for Mn-luminescence, suggesting the crystal chemistry of the host lattice is important.

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TYPE SAND Report YEAR 2011
OSTIDOI

Chemical strategies for die/wafer submicron alignment and bonding

Rohwer, Lauren E.; Chu, Dahwey C.; Martin, James E.

This late-start LDRD explores chemical strategies that will enable sub-micron alignment accuracy of dies and wafers by exploiting the interfacial energies of chemical ligands. We have micropatterned commensurate features, such as 2-d arrays of micron-sized gold lines on the die to be bonded. Each gold line is functionalized with alkanethiol ligands before the die are brought into contact. The ligand interfacial energy is minimized when the lines on the die are brought into registration, due to favorable interactions between the complementary ligand tails. After registration is achieved, standard bonding techniques are used to create precision permanent bonds. We have computed the alignment forces and torque between two surfaces patterned with arrays of lines or square pads to illustrate how best to maximize the tendency to align. We also discuss complex, aperiodic patterns such as rectilinear pad assemblies, concentric circles, and spirals that point the way towards extremely precise alignment.

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TYPE SAND Report YEAR 2010
OSTIDOI
Results 26–50 of 56
Results 26–50 of 56