Oluwadamilola Phillips

Decomposable and Template Polymers: Fundamentals and Applications

Polymers can be used as temporary place holders in the fabrication of embedded air gaps in a variety of electronic devices. Embedded air cavities can provide the lowest dielectric constant and loss for electrical insulation, mechanical compliance in devices where low-force deformations are desirable, and can temporarily protect movable parts during processing. Several families of polymers have been used as sacrificial, templating polymers including polycarbonates, polynorbornenes (PNBs), and polyaldehydes. The families can be distinguished by chemical structure and decomposition temperature. The decomposition temperature ranges from over 400 C to below room temperature in the case of low ceiling temperature polymers. Overcoat materials include silicon dioxide, polyimides, epoxy, and bis-benzocyclobutene (BCB). The methods of air-gap fabrication are discussed. Finally, the use of photoactive compounds in the patterning of the sacrificial polymers is reviewed. [DOI: 10.1115/1.4033000]

Phototriggered Depolymerization of Flexible Poly(phthalaldehyde) Substrates by Integrated Organic Light-Emitting Diodes

We demonstrate phototriggered depolymerization of a low ceiling temperature ( Tc) polymer, poly(phthalaldehyde) (PPHA), via internal light emission from integrated organic light-emitting diodes (OLEDs) fabricated directly on flexible PPHA substrates with silver nanowire electrodes. The depolymerization of the PPHA substrates is triggered by absorption of the OLED emission by a sensitizer that activates a photoacid generator via energetically favorable electron transfer. We confirm with Fourier-transform infrared spectroscopy that the photon doses delivered by the integrated OLED are sufficient to depolymerize the PPHA substrates. We determine this critical dosage by measuring the operating lifetimes of the OLEDs whose failure is believed to be due to significant mechanical softening during the liquefaction of decomposed phthalaldehyde monomers.

Phototriggerable Transient Electronics: Materials and Concepts

Transient electronics is an emerging field oftechnology where the controlled, programmable vaporizationof a device is needed because retrieval is not possible or adifferent form of disposal is desired. Decomposable polymersare of interest and may be used to form electronic componentsand packages. The ability to trigger these polymers todepolymerize and vaporize at ambient conditions can lead tomany applications. Low ceiling temperature polyaldehydeshave been evaluated for transience. Incorporation of morevolatile monomer units significantly increase the evaporationrate of decomposition products. The stimulus fordisappearance is a photochemical reaction that has beenextended from the ultraviolet to the visible region. Chemicalamplification of the trigger source has been demonstrated withacid amplifiers.

Bonding of copper surface in ambient air using propylene carbonate as passivation layer

Abstract. Bonding of a copper surface in a nonvacuum environment has been studied for the purpose of reducing manufacturing costs. Cu-Cu bonding in ambient air is demonstrated by using propylene carbonate (PPC) as a passivation layer. The decomposition of the PPC passivation layer during bonding would protect the copper surface from oxidation by providing a shielding gas atmosphere between the copper surface and the air. Further, the PPC passivation layer would also overcome the degradation of copper surface during storage in the atmosphere.