One emerging application of additive manufacturing is building parts with embedded electronics, but the thermal management of these assemblies is a potential issue. Electrical components have efficiency losses, and a significant portion of that lost energy is converted into heat. Embedding electronics in PolyJet parts is of particular interest since material jetting additive manufacturing has the ability to deposit multiple, functionally graded materials on a pixel by pixel basis. Although there is existing literature on other PolyJet material properties, there is limited research on their thermal characterization. The goal of this work is to determine the thermal conductivities of select PolyJet photopolymers (VeroWhitePlus, TangoBlackPlus, and Grey60) by using the heat flow meter method. The resulting thermal conductivities are then applied in finite element analysis (FEA) simulations to model the thermal distribution of heated PolyJet parts. Two FEA models of one-dimensional conduction in PolyJet parts are defined and compared to a corresponding physical model to verify the thermal conductivity measurements; one simulation expresses thermal conductivity as a function of temperature and the other uses an average value of thermal conductivity. The thermal conductivities were determined for a range of temperatures, and the average values were 0.2376 W/(m•K), 0.2307 W/(m•K), and 0.2272 W/(m•K) for VeroWhitePlus, TangoBlackPlus, and Grey60, respectively. When applying the thermal conductivity results to an FEA model, it was concluded that defining thermal conductivity as a function of temperature (as opposed to a constant value), reduced the average error in the predicted temperatures by less than 1%. / Master of Science

Poly(beta-amino esters) are photopolymerizable and biodegradable polymers prepared by the combination of amines with diacrylates. This study aims to fundamentally understand the polymer network formed by poly(ethylene)glycol diacrylate (PEGDA) MW 700 and 3-methoxypropylamine (3MOPA) as well as to characterize the degradation response of this material with and without cyclic loading. The networks were formed by a two-step process; (1) the synthesis of amine-co-peg diacrylate macromers through a step growth reaction, followed by (2) UV initiated chain growth network formation of the diacrylated macromers. Macromer reaction chemistry was confirmed by 1H NMR measurements. UV calorimetric analysis revealed that network formation was dependent on molecular weight of the PEGDA monomer and light intensity, but not temperature in the range of 20 °C to 40 °C. The glass transition temperature of all networks was measured to be in the range of -40 °C to -30°C with a rubbery moduli ranging from 4 to 10 MPa, depending on the molecular weight of the PEGDA monomer. Partial crystallization was discovered to occur in the networks containing higher molecular weight PEGDA only in the presence of humidity and high frequency cyclic loading. Degradation studies were performed with and without applied cyclical stress, and in both cases elastic modulus decrease and mass loss occurred steadily over a 24-hour period. Increasing frequency of applied compressive stress during degradation served to slightly lower degradation rates, especially in samples cycled at high frequency, which crystallized. In all materials, applied cyclic load resulted in catastrophic fracture of the material prior to an appreciable decrease in modulus. The experiments reveal that degradation rate and failure mode can be influenced by the addition of cyclic loading and this should be considered when screening biodegradable polymers for applications that include mechanical loading.

To enable fast and reliable processors, advances must be made in the interconnections on the printed circuit board and in the interconnections from the chip to the printed circuit board. Processing techniques have been demonstrated to fabricate a copper-clad encapsulated air dielectric layer to enable low loss off-chip electrical signal lines using sacrificial polymers and the three dimensional patterning capabilities of imprint lithography. The inclusion of an air gap can eliminate the dielectric loss allowing the signal to propagate over longer lengths. Additionally, the low dielectric constant of air lowers the loss contributions from the conductor and increases the signal propagation velocity reducing delay. The metal shielding could minimize the crosstalk noise and radiation losses that are significant at high frequencies. The three dimensional patterning capabilities of imprint lithography fabricated curved structures and rounded terminations which can reduce reflections at discontinuities. Furthermore, imprint lithography also created planarized surfaces which simplified the buildup process. Since imprint lithography, only uses temperature and pressure to make a pattern it is an inexpensive and simple process advancement. The metal-clad encapsulated air dielectric structures were fabricated in a comparable number of registration steps to traditional transmission lines. Implementation of all copper chip to substrate interconnects would provide high conductivity electrical connections, resistance to electromigration while avoiding formation of brittle intermetallics. High aspect ratio polymer molds for copper electroplating interconnects could enable improved integrated circuit electrical performance. The properties of a new aqueous base develop, negative-tone photosensitive polynorbornene polymer have been characterized to develop mechanically compliant all copper connections between the chip and printed circuit board. High aspect ratio features of 7:1 (height:width) were produced in 70 ìm thick films in a single coat with straight side-wall profiles and high fidelity. The polymer films studied had a contrast of 11.6 and a low absorption coefficient. To evaluate the polymer's suitability to microelectronics applications, epoxy cross-linking reactions were studied as a function of processing condition through Fourier transform infrared spectroscopy, nano-indentation, and dielectric measurements. The fully cross-linked films had an elastic modulus of 2.9 GPa and hardness of 0.18 GPa which can improve the mechanical compliance of the copper interconnections. A photo-imprint lithography process was developed to improve the photo-patterning of the polynorbornene polymer for high aspect ratio hollow structures. A shallow photo-imprint stamp was developed to physically displace material in the polymer core. Since the imprint stamp displaces material in the area of the feature, the effective film thickness is reduced compared to the bulk film. The reduction in film height reduced the effects of scattering in the core and also facilitated transport of developer within the core. The photo-imprint lithography process resulted in high aspect ratio hollow core pillars that exceeded optical resolution capabilities for comparable feature sizes.

Polymers play an integral part in the semiconductor electronic industry. Due to the expanding diversity of a polymer s structural design and the resulting properties, different polymers serve as different components in the makeup and fabrication of the electronic package. The limiting factor in computer processing speed shifts from the transistors gate delay to the interconnect delay below a circuit line width of 1.8 μm for interlayer dielectrics. Silicon dioxide has been used as the insulating layer between metal lines for many computer chip generations. Low dielectric constant polymers will need to supplant silicon dioxide as interlayer dielectrics in order to develop reliable circuits for future generations. Along with serving as interlayer dielectrics, low dielectric constant polymers are also incorporated in first and second level electronic packaging. Deposition and patterning of these polymers can be significantly reduced by using photodefinable polymers. Most photodefinable polymers are in a precursor form for exposure and development in order to dissolve in industrial developers. Once developed, the polymer precursors are cured to produce the final polymer structure. This temperature is as high as 350 oC for many polymers. Thermal curing sets limitations on the use of the polymer in the electronics industry because of either the unwanted stress produced or the incompatibility of other electronic components that do not survive the thermal cure. In addition to a low dielectric constant and photodefinability, many other properties are needed for successful implementation. Polymers must be soluble in organic solvents in order to spin coat films. Water absorption increases the dielectric constant of the patterned films and can lead to various adhesion problems and cause delamination of the film. Mismatches between the coefficients of thermal expansion in adjacent layers can produce residual film stresses which leads to warping of the substrate or interfacial delamination. The glass transition temperature must be high because the thermal expansion is greatly increased when the glass transition temperature is exceeded. A high Young s modulus is also required to withstand external forces from thermal, electrical, and packaging stresses. The goal of this research was to develop novel, low dielectric, photodefinable polymers that can be processed at low temperatures. All polymers discussed will contain one of two monomers with hexafluoroalcohol (HFA) functional groups. Fluorine provides many properties that are advantageous for low dielectric applications whereas alcohols absorb water and increase the dielectric constant. Characterization of the polymers show the effect the fluorine has on the alcohol s high water absorption. All polymers will be synthesized by condensation polymerization of a diamine with a dianhydride or diacid chloride. All other polymers will contain a novel HFA diamine. A new thermoplastic polymer structure based on the cyclization of an HFA situated ortho to an amide linkage produces a benzoxazine ring in the polymer backbone. Cyclization to form polybenzoxazines occurs at temperatures considerably lower than that needed to form polyimides. The lowest processing temperatures are achieved with protection of the HFA that can be cleaved with a photoacid generator.

The miniaturization of optical systems has been a longstanding interest for physicists. By facilitating the design of smaller optical systems, we can improve their versatility and cost-effectiveness. This aim applies to macroscopic imaging systems, technologies that implicitly image, and micrometer-scale optics. Parallel to this, quantum optical devices have also seen rapid developments. Notably, the need for new quantum communications and quantum imaging devices has recently risen. The thesis outlines advancements in both of these areas and, in many ways, bridges gaps between them. It discusses the development of optics that compress free space, the design of holographic optical elements, and the generation of entangled photon states in thin-film sources. First, we describe an optic designed to miniaturize free space, termed the spaceplate. Spaceplates achieve the propagation of light for a distance greater than their thickness.Therefore, they compress optical space, reducing the required distance between optical elements in an imaging system. In this thesis, we describe a spaceplate based on conventional optics in a 4-f arrangement, mimicking the transfer function of free space in a thinner system - we term this device a three-lens spaceplate. It is broadband, polarization-independent, and achieves meter-scale space compression. We experimentally measure compression ratios up to 15.6, replacing up to 4.4 meters of free space, three orders of magnitude greater than previous spaceplates. We demonstrate that three-lens spaceplates reduce the length of a full-color imaging system, albeit with reductions in resolution and contrast. We also present theoretical limits on the numerical aperture and the compression ratio. Our design presents a simple, accessible, cost-effective method for optically compressing large volumes of space. Second, we discuss the design of holographic optical elements. Holograms are extraordinarily versatile optics. They have many applications, including interferometry, spectrometry, data storage, optical filtration, and sensing. We can design various optical elements such as filters, lenses, beam splitters, and solar concentrators by tailoring the phase response of a hologram. In this thesis, we describe the nature and function of holograms, and we experimentally characterize holography in lithium niobate and photopolymers. Using this characterization, we assess the limitations of different holographic analysis methods. Further, we describe novel holographic optical elements like the holographic spaceplate - a holographic optic element whose phase response mimics free space. Lastly, this thesis outlines the production of entangled photon pairs, or biphotons, via non-phase-matched spontaneous parametric down-conversion in micrometer- and nanometer-scale devices. By producing biphotons in micrometer-scale crystals rather than in bulk, as is done traditionally, we are allowed to ignore phase matching. These devices produce broadband emission in both angle and frequency not seen in phase-matched bulk sources. We measure entangled biphotons produced via spontaneous parametric down-conversion in gallium arsenide (111) and lithium niobate - both undoped and iron-doped. Lastly, we outline and present initial experiments towards a holographic spontaneous parametric down-conversion optic that combines photon production and mode sorting - an optic of cascaded miniaturization.

<p>A model with nonlinear Schrödinger (NLS) equation used for describing pulse propagations in photopolymers is considered. We focus on a case in which change of refractive index is proportional to the square of amplitude of the electric field and consider 2-dimensional spatial domain. After formal derivation of the NLS approximation from the wave-Maxwell equation, we establish well-posedness and perform rigorous justification analysis to show smallness of error terms for appropriately small time intervals. We conclude by numerical simulation to illustrate the results in one-dimensional case.</p> / Master of Science (MSc)

Ces travaux de thèse portent sur le développement d’un procédé de photopolymérisation de films poly(disulfure) en une seule étape. Pour la première fois, un film poly(disulfure), sec après seulement quelques minutes d’irradiation UV, a été obtenu par oxydation de dérivés thiol sous air en présence d’un photogénérateur de base (PBG). Une investigation poussée du mécanisme d’oxydation de monomères thiol sous air a permis d’identifier deux paramètres clefs : la présence de la superbase dans le milieu libérée après irradiation du PBG et une bonne perméation de l’oxygène. Il a également été démontré qu’un second mécanisme menant à la formation de ponts disulfure a lieu par arrachement d’hydrogène des fonctions thiol par les rayons UV les plus énergétiques. La prédominance de ces mécanismes dépend de la source d’irradiation choisie. Ce procédé a été appliqué avec succès à une gamme de monomères et oligomères thiol, permettant une modulation des propriétés finales du film selon les composés utilisés. Une seconde partie de la thèse a porté sur la photopolymérisation de résines commerciales poly(disulfure) liquides fonctionnalisées par des groupements thiols. Le caractère dynamique des ponts disulfure présents avant irradiation a mené à l’observation de deux comportements : une photopolymérisation oxydative des fonctions thiol sous irradiation LED à 365 nm en présence de PBG ou une photoréticulation par réarrangement des liaisons disulfure sous irradiation UV en absence de PBG. Enfin, l’effort de valorisation des films poly(disulfure) s’est traduit par l’obtention de motifs poly(disulfure) par photolithographie UV et la dégradation de ces films en présence d’un agent réducteur. / This thesis reports an innovative single-step photopolymerization process of poly(disulfide) films. A dry poly(disulfide) film has been obtained after only few minutes of UV irradiation via photobase-catalyzed thiol oxidative coupling under air. Two critical parameters were identified by an in-depth investigation of the thiol oxidative mechanism under air: the presence of the superbase released after irradiation of the photobase generator (PBG) and a good atmospheric oxygen permeability. It has also been demonstrated that a second mechanism leading to the formation of disulfide bridges takes place by thiol photolysis when irradiated with deep UV. The predominance of these mechanisms depends on the source of irradiation used. This process has been successfully applied to a range of thiol monomers and oligomers, making it possible to tailor final properties of the film depending on the compounds used. A second part has been focused on the photopolymerization of commercial liquid poly(disulfide) resins with terminal thiol functions. The dynamic behavior of disulfide bridges has induced two different results: an oxidative photopolymerization of thiol functions under LED irradiation with PBG and a photo cross-linking by rearrangement of disulfide bounds under UV irradiation without any PBG. Finally, in order to value the interest of these photogenerated poly(disulfide), a photopatterned film has been successfully obtained and reductive cleavage of S-S bonds has led to film degradation.

Dans cette thèse, nous développons des micro-concentrateurs de lumière en vue d’applications dans l’infrarouge. Les optiques, plates, de dimensions comparables à la longueur d’onde, sont formées d’une couche micronique de métamatériau, constituée de polymère structuré par des trous d’air. Une focalisation dans la zone de Fresnel des structures est recherchée en réalisant un gradient d’indice, obtenu en variant le diamètre des inclusions d’air (de λ//20 à λ/8). Des simulations électromagnétiques sont d’abord effectuées pour valider un design. La fabrication de ces concentrateurs repose sur la structuration d’une couche de photorésine à l’aide d’une technique de lithographie optique 3D à deux photons. Les mesures obtenues par l’imagerie infrarouge des structures montrent l’obtention d’une focalisation en accord avec les simulations pour un volume de concentrateur de 1,5 λ³, en dépit de l’absorption résiduelle de la résine choisie. Les structures proposées sont invariantes dans la direction axiale et peu épaisses, et peuvent donc être transférées dans d’autres types de matériaux ayant des indices de réfraction plus importants, comme le silicium. Les structures proposées peuvent également servir de plateforme pour réaliser un confinement sub-longueur d’onde par l’ajout d’antennes plasmoniques / In this thesis, we develop flat light concentrators for infrared applications. The structures have dimensions comparable with the wavelength and are made of a metamaterial layer (few microns) made of polymer with air holes inclusions. Light focusing in the Fresnel zone of the structures is achieved by a gradient index profile obained by chirping the holes diameter (from λ//20 to λ/8). Electromagnetic simulations are first performed to validate a design. The fabrication of these concentrators is then made by direct laser writing using a 3D two-photon lithography technique. Infrared imaging of the structures reveals a clear focusing of the infrared light for concentrators volume as small as 1,5 λ³, in agreement with the electromagnetic simulations. Considering that the metamaterial concentrator slabs are invariant in the axial direction and not too thick, similar structures can be transferred in transparent substrates such as silicon using deep reactive ion etching. A subwavelength light confinement can also be exploited by adding plasmonic antenna on the top surface of the flat concentrators