The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Placid M. Ferreira - One of the best experts on this subject based on the ideXlab platform.
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Multi-physics modeling for laser micro-transfer printing delamination
Journal of Manufacturing Processes, 2015Co-Authors: Ala'a M. Al-okaily, Placid M. FerreiraAbstract:Micro-transfer printing technology is rapidly emerging as an effective pathway for large-scale heterogeneous materials integration. In its basic embodiment, micro-transfer printing is used to deterministically transfer and micro-assemble prefabricated structures/devices, referred to as "ink," from a donor Substrate to a Receiving Substrate using a viscoelastic elastomer stamp, usually made out of polydimethylsiloxane (PDMS). Laser Micro Transfer Printing (LMTP) is a laser-driven non-contact variant of the process that makes it independent of the Receiving Substrate's properties, geometry, and preparation. In this paper, an opto-thermo-mechanical model is developed to understand how the laser beam energy is converted to thermally-induced strains around the ink-stamp interface to initiate the ink delamination process. The opto-thermo-mechanical model is developed based on decoupling the optical absorption physics from the thermo-mechanical model physics. An optical absorption model for the laser beam energy absorbed by the ink is first developed and verified experimentally to estimate the heating rates of the ink-stamp system, which in turn are used as an input for a couple thermo-mechanical Finite Element Analysis (FEA) model. Further, high speed camera recordings for LMTP delamination are used to calibrate the thermo-mechanical model and verify its predictions. Besides providing a fundamental understanding of the delamination mechanism and the LMTP process capabilities, the developed opto-thermo-mechanical model is useful in selecting process parameters (laser pulse duration, stand-off distance), estimating the ink-stamp temperature rise during the LMTP process, and quantifying and decomposing the stresses at the ink-stamp interface to its main sources (Coefficient of Thermal Expansion (CTE) mismatch and thermal gradient strains).
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Process Performance of Silicon Thin-Film Transfer Using Laser Micro-Transfer Printing
Volume 2B: Advanced Manufacturing, 2014Co-Authors: Ala'a M. Al-okaily, Placid M. FerreiraAbstract:Micro-transfer printing is rapidly emerging as an effective pathway for heterogeneous materials integration. The process transfers pre-fabricated micro- and nano-scale structures, referred to as “ink,” from growth donor Substrates to functional Receiving Substrates. As a non-contact pattern transfer method, Laser Micro-Transfer Printing (LMTP) has been introduced to enhance the capabilities of transfer printing technology to be independent of the Receiving Substrate material, geometry, and preparation. Using micro fabricated square silicon as inks and polydimethylsiloxane (PDMS) as the stamp material. The previous work on the LMTP process focused on experimentally characterizing and modeling the effects of transferred inks’ sizes and thicknesses, and laser beam powers on the laser-driven delamination process mechanism. In this paper, several studies are conducted to understand the effects of other process parameters such as stamp post dimensions (size and height), PDMS formulation for the stamp, ink-stamp alignment, and the shape of the transferred silicon inks on the LMTP performance and mechanism. The studies are supported by both experimental data for the laser pulse duration required to initiate the delamination, and thermo-mechanical FEA model predictions of the energy stored at the interface’s edges to release the ink (Energy Release Rate (ERR)), stress levels at the delamination crack tip (Stress Intensity Factors (SIFs)), and interfacial temperature. This study, along with previous studies, should help LMTP users to understand the effects of the process parameters on the process performance so as to select optimal operation conditions.© 2014 ASME
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Characterization of Delamination in Laser Microtransfer Printing
Journal of Micro and Nano-Manufacturing, 2014Co-Authors: Ala'a M. Al-okaily, John A. Rogers, Placid M. FerreiraAbstract:Microtransfer printing is rapidly emerging as an effective method for heterogeneous materials integration. Laser microtransfer printing (LMTP) is a noncontact variant of the process that uses laser heating to drive the release of the microstructure from the stamp. This makes the process independent of the properties or preparation of the Receiving Substrate. In this paper, an extensive study is conducted to investigate the capability of the LMTP process. Furthermore, a thermomechanical finite element model (FEM) is developed, using the experimentally observed delamination times and absorbed powers, to estimate the delamination temperatures at the interface, as well as the strain, displacement, and thermal gradient fields.
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Characterization of Delamination in Laser Micro Transfer Printing
Volume 2A: Advanced Manufacturing, 2013Co-Authors: Ala'a M. Al-okaily, Placid M. FerreiraAbstract:Micro transfer printing is rapidly emerging as an effective method for heterogeneous materials integration. It transfers prefabricated micro- and nanoscale structures referred to as ‘inks’, from growth or fabrication donor Substrates to functional receiver Substrates. Laser Micro Transfer Printing (LMTP) is a laser-driven version of the micro transfer printing process, developed at the University of Illinois to enable non-contact release of the microstructure, thus making the transfer printing process independent of the properties or preparation of the Receiving Substrate. In this paper, an extensive study is conducted to investigate the capability of the LMTP process. Using square shaped silicon inks and polydimethylsiloxane (PDMS) stamps, and varying the lateral dimensions and thickness of the ink, the power absorption by the ink is measured to estimate the total energy stored in the ink-stamp system to initiate and propagate delamination at the interface. The delamination time for each size and thickness is experimentally observed at different laser beam powers using a high speed camera. Further, an axisymmetric thermo-mechanical FEM is developed to estimate the delamination temperatures at the interface utilizing the delamination time and power absorption for different ink sizes and thickness.Copyright © 2013 by ASME
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A prototype printer for laser driven micro-transfer printing
Journal of Manufacturing Processes, 2012Co-Authors: Reza Saeidpourazar, Michael D. Sangid, John A. Rogers, Placid M. FerreiraAbstract:Abstract This paper demonstrates a new mode of automated micro transfer printing called laser micro transfer printing (LμTP). As a process, micro-transfer printing provides a unique and critical manufacturing route to extracting active microstructures from growth Substrates and deterministically assembling them into a variety of functional Substrates ranging from polymers to glasses and ceramics and to metallic foils to support applications such as flexible, large-area electronics, concentrating photovoltaics and displays. Laser transfer printing extends micro-transfer printing technology by providing a non-contact approach that is insensitive to the preparation and properties of the Receiving Substrate. It does so by exploiting the difference in the thermo-mechanical responses of the microstructure and transfer printing stamp materials to drive the release of the microstructure or ‘ink’ from the stamp and its transfer to Substrate. This paper describes the process and the physical phenomena that drive it. It focuses on the use of this knowledge to design and test a print head for the process. The print head is used to demonstrate the new printing capabilities that LμTP enables.
John A. Rogers - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Delamination in Laser Microtransfer Printing
Journal of Micro and Nano-Manufacturing, 2014Co-Authors: Ala'a M. Al-okaily, John A. Rogers, Placid M. FerreiraAbstract:Microtransfer printing is rapidly emerging as an effective method for heterogeneous materials integration. Laser microtransfer printing (LMTP) is a noncontact variant of the process that uses laser heating to drive the release of the microstructure from the stamp. This makes the process independent of the properties or preparation of the Receiving Substrate. In this paper, an extensive study is conducted to investigate the capability of the LMTP process. Furthermore, a thermomechanical finite element model (FEM) is developed, using the experimentally observed delamination times and absorbed powers, to estimate the delamination temperatures at the interface, as well as the strain, displacement, and thermal gradient fields.
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A prototype printer for laser driven micro-transfer printing
Journal of Manufacturing Processes, 2012Co-Authors: Reza Saeidpourazar, Michael D. Sangid, John A. Rogers, Placid M. FerreiraAbstract:Abstract This paper demonstrates a new mode of automated micro transfer printing called laser micro transfer printing (LμTP). As a process, micro-transfer printing provides a unique and critical manufacturing route to extracting active microstructures from growth Substrates and deterministically assembling them into a variety of functional Substrates ranging from polymers to glasses and ceramics and to metallic foils to support applications such as flexible, large-area electronics, concentrating photovoltaics and displays. Laser transfer printing extends micro-transfer printing technology by providing a non-contact approach that is insensitive to the preparation and properties of the Receiving Substrate. It does so by exploiting the difference in the thermo-mechanical responses of the microstructure and transfer printing stamp materials to drive the release of the microstructure or ‘ink’ from the stamp and its transfer to Substrate. This paper describes the process and the physical phenomena that drive it. It focuses on the use of this knowledge to design and test a print head for the process. The print head is used to demonstrate the new printing capabilities that LμTP enables.
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Axisymmetric thermo-mechanical analysis of laser-driven non-contact transfer printing
International Journal of Fracture, 2012Co-Authors: Rui Li, Placid M. Ferreira, Reza Saeidpourazar, Jizhou Song, John A. Rogers, Chaofeng Lü, Yang Zhong, Yuhang Li, Bo Fang, Yonggang HuangAbstract:An axisymmetric thermo-mechanical model is developed for laser-driven non-contact transfer printing, which involves laser-induced impulsive heating to initiate separation at the interface between a soft, elastomeric stamp and hard micro/nanomaterials (i.e., inks) on its surface, due to a large mismatch in coefficients of thermal expansion. The result is the active ejection of the inks from the stamp, to a spatially separated Receiving Substrate, thereby representing the printing step. The model gives analytically the temperature field, and also a scaling law for the energy release rate for delamination at the interface between the stamp and an ink in the form of a rigid plate. The normalized critical laser pulse time for interfacial delamination depends only on the normalized absorbed laser power and width of the ink structure, and has been verified by experiments.
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A prototype printer for laser driven micro-transfer printing
Journal of Manufacturing Processes, 2012Co-Authors: Reza Saeidpourazar, Michael D. Sangid, John A. Rogers, Placid M. FerreiraAbstract:This paper demonstrates a new mode of automated micro transfer printing called laser micro transfer printing (LμTP). As a process, micro-transfer printing provides a unique and critical manufacturing route to extracting active microstructures from growth Substrates and deterministically assembling them into a variety of functional Substrates ranging from polymers to glasses and ceramics and to metallic foils to support applications such as flexible, large-area electronics, concentrating photovoltaics and displays. Laser transfer printing extends micro-transfer printing technology by providing a non-contact approach that is insensitive to the preparation and properties of the Receiving Substrate. It does so by exploiting the difference in the thermo-mechanical responses of the microstructure and transfer printing stamp materials to drive the release of the microstructure or 'ink' from the stamp and its transfer to Substrate. This paper describes the process and the physical phenomena that drive it. It focuses on the use of this knowledge to design and test a print head for the process. The print head is used to demonstrate the new printing capabilities that LμTP enables. © 2012 The Society of Manufacturing Engineers.
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Thermo-mechanical modeling of laser-driven non-contact transfer printing: two-dimensional analysis
Soft Matter, 2012Co-Authors: Rui Li, Reza Saeidpouraza, Placid M. Ferreira, Jizhou Song, John A. Rogers, Chaofeng Lü, Yang Zhong, Yuhang Li, Bo Fang, Yonggang HuangAbstract:Transfer printing is an emerging technique for materials assembly and micro-/nano-fabrication. An important emerging variant of this process involves laser-induced impulsive heating to initiate separation at the interface between a soft, elastomeric stamp and hard micro-/nano-materials (i.e. inks) on its surface, due to a large mismatch in coefficients of thermal expansion. The result is the active ejection of the inks from the stamp to a spatially separated Receiving Substrate, thereby representing the printing step. In the following, a thermo-mechanical model is established to analytically obtain the temperature field, and the energy release rate for delamination at the interface between the stamp and ink in the form of a rigid plate. The normalized critical laser pulse time for interfacial delamination depends only on the normalized total heat flux at the interface and the normalized width of the ink structure. This scaling law has been verified by experiments and the finite element method.
Reza Saeidpourazar - One of the best experts on this subject based on the ideXlab platform.
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A prototype printer for laser driven micro-transfer printing
Journal of Manufacturing Processes, 2012Co-Authors: Reza Saeidpourazar, Michael D. Sangid, John A. Rogers, Placid M. FerreiraAbstract:Abstract This paper demonstrates a new mode of automated micro transfer printing called laser micro transfer printing (LμTP). As a process, micro-transfer printing provides a unique and critical manufacturing route to extracting active microstructures from growth Substrates and deterministically assembling them into a variety of functional Substrates ranging from polymers to glasses and ceramics and to metallic foils to support applications such as flexible, large-area electronics, concentrating photovoltaics and displays. Laser transfer printing extends micro-transfer printing technology by providing a non-contact approach that is insensitive to the preparation and properties of the Receiving Substrate. It does so by exploiting the difference in the thermo-mechanical responses of the microstructure and transfer printing stamp materials to drive the release of the microstructure or ‘ink’ from the stamp and its transfer to Substrate. This paper describes the process and the physical phenomena that drive it. It focuses on the use of this knowledge to design and test a print head for the process. The print head is used to demonstrate the new printing capabilities that LμTP enables.
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Axisymmetric thermo-mechanical analysis of laser-driven non-contact transfer printing
International Journal of Fracture, 2012Co-Authors: Rui Li, Placid M. Ferreira, Reza Saeidpourazar, Jizhou Song, John A. Rogers, Chaofeng Lü, Yang Zhong, Yuhang Li, Bo Fang, Yonggang HuangAbstract:An axisymmetric thermo-mechanical model is developed for laser-driven non-contact transfer printing, which involves laser-induced impulsive heating to initiate separation at the interface between a soft, elastomeric stamp and hard micro/nanomaterials (i.e., inks) on its surface, due to a large mismatch in coefficients of thermal expansion. The result is the active ejection of the inks from the stamp, to a spatially separated Receiving Substrate, thereby representing the printing step. The model gives analytically the temperature field, and also a scaling law for the energy release rate for delamination at the interface between the stamp and an ink in the form of a rigid plate. The normalized critical laser pulse time for interfacial delamination depends only on the normalized absorbed laser power and width of the ink structure, and has been verified by experiments.
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A prototype printer for laser driven micro-transfer printing
Journal of Manufacturing Processes, 2012Co-Authors: Reza Saeidpourazar, Michael D. Sangid, John A. Rogers, Placid M. FerreiraAbstract:This paper demonstrates a new mode of automated micro transfer printing called laser micro transfer printing (LμTP). As a process, micro-transfer printing provides a unique and critical manufacturing route to extracting active microstructures from growth Substrates and deterministically assembling them into a variety of functional Substrates ranging from polymers to glasses and ceramics and to metallic foils to support applications such as flexible, large-area electronics, concentrating photovoltaics and displays. Laser transfer printing extends micro-transfer printing technology by providing a non-contact approach that is insensitive to the preparation and properties of the Receiving Substrate. It does so by exploiting the difference in the thermo-mechanical responses of the microstructure and transfer printing stamp materials to drive the release of the microstructure or 'ink' from the stamp and its transfer to Substrate. This paper describes the process and the physical phenomena that drive it. It focuses on the use of this knowledge to design and test a print head for the process. The print head is used to demonstrate the new printing capabilities that LμTP enables. © 2012 The Society of Manufacturing Engineers.
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Axisymmetric thermo-mechanical analysis of laser-driven non-contact transfer printing
International Journal of Fracture, 2012Co-Authors: Rui Li, Placid M. Ferreira, Reza Saeidpourazar, Jizhou Song, John A. Rogers, Chaofeng Lü, Yang Zhong, Yuhang Li, Bo Fang, Yonggang HuangAbstract:An axisymmetric thermo-mechanical model is developed for laser-driven non-contact transfer printing, which involves laser-induced impulsive heating to initiate separation at the interface between a soft, elastomeric stamp and hard micro/nanomaterials (i.e., inks) on its surface, due to a large mismatch in coefficients of thermal expansion. The result is the active ejection of the inks from the stamp, to a spatially separated Receiving Substrate, thereby representing the printing step. The model gives analytically the temperature field, and also a scaling law for the energy release rate for delamination at the interface between the stamp and an ink in the form of a rigid plate. The normalized critical laser pulse time for interfacial delamination depends only on the normalized absorbed laser power and width of the ink structure, and has been verified by experiments. © Springer Science+Business Media B.V. 2012.
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Laser-Driven Micro Transfer Placement of Prefabricated Microstructures
Journal of Microelectromechanical Systems, 2012Co-Authors: Reza Saeidpourazar, Michael D. Sangid, John A. Rogers, Chaofeng Lü, Yuhang Li, Rui Li, Yonggang Huang, Placid M. FerreiraAbstract:Microassembly of prefabricated structures and devices is emerging as key process technology for realizing heterogeneous integration and high-performance flexible and stretchable electronics. Here, we report on a laser-driven micro transfer placement process that exploits, instead of ablation, the mismatch in thermomechanical response at the interface of a transferable microstructure and a transfer tool to a laser pulse to drive the release of the microstructure from the transfer tool and its travel to a Receiving Substrate. The resulting facile pick-and-place process is demonstrated with the assembling of 3-D microstructures and the placement of GaN light-emitting diodes onto silicon and glass Substrates. High-speed photography is used to provide experimental evidence of thermomechanically driven release. Experiments are used to measure the laser flux incident on the interface. These, when used in numerical and analytical models, suggest that temperatures reached during the process are enough to produce strain energy release rates to drive delamination of the microstructure from the transfer tool.
Yonggang Huang - One of the best experts on this subject based on the ideXlab platform.
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Axisymmetric thermo-mechanical analysis of laser-driven non-contact transfer printing
International Journal of Fracture, 2012Co-Authors: Rui Li, Placid M. Ferreira, Reza Saeidpourazar, Jizhou Song, John A. Rogers, Chaofeng Lü, Yang Zhong, Yuhang Li, Bo Fang, Yonggang HuangAbstract:An axisymmetric thermo-mechanical model is developed for laser-driven non-contact transfer printing, which involves laser-induced impulsive heating to initiate separation at the interface between a soft, elastomeric stamp and hard micro/nanomaterials (i.e., inks) on its surface, due to a large mismatch in coefficients of thermal expansion. The result is the active ejection of the inks from the stamp, to a spatially separated Receiving Substrate, thereby representing the printing step. The model gives analytically the temperature field, and also a scaling law for the energy release rate for delamination at the interface between the stamp and an ink in the form of a rigid plate. The normalized critical laser pulse time for interfacial delamination depends only on the normalized absorbed laser power and width of the ink structure, and has been verified by experiments.
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Axisymmetric thermo-mechanical analysis of laser-driven non-contact transfer printing
International Journal of Fracture, 2012Co-Authors: Rui Li, Placid M. Ferreira, Reza Saeidpourazar, Jizhou Song, John A. Rogers, Chaofeng Lü, Yang Zhong, Yuhang Li, Bo Fang, Yonggang HuangAbstract:An axisymmetric thermo-mechanical model is developed for laser-driven non-contact transfer printing, which involves laser-induced impulsive heating to initiate separation at the interface between a soft, elastomeric stamp and hard micro/nanomaterials (i.e., inks) on its surface, due to a large mismatch in coefficients of thermal expansion. The result is the active ejection of the inks from the stamp, to a spatially separated Receiving Substrate, thereby representing the printing step. The model gives analytically the temperature field, and also a scaling law for the energy release rate for delamination at the interface between the stamp and an ink in the form of a rigid plate. The normalized critical laser pulse time for interfacial delamination depends only on the normalized absorbed laser power and width of the ink structure, and has been verified by experiments. © Springer Science+Business Media B.V. 2012.
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Thermo-mechanical modeling of laser-driven non-contact transfer printing: two-dimensional analysis
Soft Matter, 2012Co-Authors: Rui Li, Reza Saeidpouraza, Placid M. Ferreira, Jizhou Song, John A. Rogers, Chaofeng Lü, Yang Zhong, Yuhang Li, Bo Fang, Yonggang HuangAbstract:Transfer printing is an emerging technique for materials assembly and micro-/nano-fabrication. An important emerging variant of this process involves laser-induced impulsive heating to initiate separation at the interface between a soft, elastomeric stamp and hard micro-/nano-materials (i.e. inks) on its surface, due to a large mismatch in coefficients of thermal expansion. The result is the active ejection of the inks from the stamp to a spatially separated Receiving Substrate, thereby representing the printing step. In the following, a thermo-mechanical model is established to analytically obtain the temperature field, and the energy release rate for delamination at the interface between the stamp and ink in the form of a rigid plate. The normalized critical laser pulse time for interfacial delamination depends only on the normalized total heat flux at the interface and the normalized width of the ink structure. This scaling law has been verified by experiments and the finite element method.
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Laser-Driven Micro Transfer Placement of Prefabricated Microstructures
Journal of Microelectromechanical Systems, 2012Co-Authors: Reza Saeidpourazar, Michael D. Sangid, John A. Rogers, Chaofeng Lü, Yuhang Li, Rui Li, Yonggang Huang, Placid M. FerreiraAbstract:Microassembly of prefabricated structures and devices is emerging as key process technology for realizing heterogeneous integration and high-performance flexible and stretchable electronics. Here, we report on a laser-driven micro transfer placement process that exploits, instead of ablation, the mismatch in thermomechanical response at the interface of a transferable microstructure and a transfer tool to a laser pulse to drive the release of the microstructure from the transfer tool and its travel to a Receiving Substrate. The resulting facile pick-and-place process is demonstrated with the assembling of 3-D microstructures and the placement of GaN light-emitting diodes onto silicon and glass Substrates. High-speed photography is used to provide experimental evidence of thermomechanically driven release. Experiments are used to measure the laser flux incident on the interface. These, when used in numerical and analytical models, suggest that temperatures reached during the process are enough to produce strain energy release rates to drive delamination of the microstructure from the transfer tool.
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Competing fracture in kinetically controlled transfer printing
Langmuir, 2007Co-Authors: Xue Feng, Audrey M. Bowen, Matthew A. Meitl, Ralph G. Nuzzo, Yonggang Huang, John A. RogersAbstract:Transfer printing by kinetically switchable adhesion to an elastomeric stamp shows promise as a powerful micromanufacturing method to pickup microstructures and microdevices from the donor Substrate and to print them to the Receiving Substrate. This can be viewed as the competing fracture of two interfaces. This paper examines the mechanics of competing fracture in a model transfer printing system composed of three laminates: an elastic Substrate, an elastic thin film, and a viscoelastic member (stamp). As the system is peeled apart, either the interface between the Substrate and thin film fails or the interface between the thin film and the stamp fails. The speed-dependent nature of the film/stamp interface leads to the prediction of a critical separation velocity above which separation occurs between the film and the Substrate (i.e., pickup) and below which separation occurs between the film and the stamp (i.e., printing). Experiments verify this prediction using films of gold adhered to glass, and the theoretical treatment extends to consider the competing fracture as it applies to discrete micro-objects. Temperature plays an important role in kinetically controlled transfer printing with its influences, making it advantageous to pickup printable objects at the reduced temperatures and to print them at the elevated ones.
Ala'a M. Al-okaily - One of the best experts on this subject based on the ideXlab platform.
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Multi-physics modeling for laser micro-transfer printing delamination
Journal of Manufacturing Processes, 2015Co-Authors: Ala'a M. Al-okaily, Placid M. FerreiraAbstract:Micro-transfer printing technology is rapidly emerging as an effective pathway for large-scale heterogeneous materials integration. In its basic embodiment, micro-transfer printing is used to deterministically transfer and micro-assemble prefabricated structures/devices, referred to as "ink," from a donor Substrate to a Receiving Substrate using a viscoelastic elastomer stamp, usually made out of polydimethylsiloxane (PDMS). Laser Micro Transfer Printing (LMTP) is a laser-driven non-contact variant of the process that makes it independent of the Receiving Substrate's properties, geometry, and preparation. In this paper, an opto-thermo-mechanical model is developed to understand how the laser beam energy is converted to thermally-induced strains around the ink-stamp interface to initiate the ink delamination process. The opto-thermo-mechanical model is developed based on decoupling the optical absorption physics from the thermo-mechanical model physics. An optical absorption model for the laser beam energy absorbed by the ink is first developed and verified experimentally to estimate the heating rates of the ink-stamp system, which in turn are used as an input for a couple thermo-mechanical Finite Element Analysis (FEA) model. Further, high speed camera recordings for LMTP delamination are used to calibrate the thermo-mechanical model and verify its predictions. Besides providing a fundamental understanding of the delamination mechanism and the LMTP process capabilities, the developed opto-thermo-mechanical model is useful in selecting process parameters (laser pulse duration, stand-off distance), estimating the ink-stamp temperature rise during the LMTP process, and quantifying and decomposing the stresses at the ink-stamp interface to its main sources (Coefficient of Thermal Expansion (CTE) mismatch and thermal gradient strains).
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Process Performance of Silicon Thin-Film Transfer Using Laser Micro-Transfer Printing
Volume 2B: Advanced Manufacturing, 2014Co-Authors: Ala'a M. Al-okaily, Placid M. FerreiraAbstract:Micro-transfer printing is rapidly emerging as an effective pathway for heterogeneous materials integration. The process transfers pre-fabricated micro- and nano-scale structures, referred to as “ink,” from growth donor Substrates to functional Receiving Substrates. As a non-contact pattern transfer method, Laser Micro-Transfer Printing (LMTP) has been introduced to enhance the capabilities of transfer printing technology to be independent of the Receiving Substrate material, geometry, and preparation. Using micro fabricated square silicon as inks and polydimethylsiloxane (PDMS) as the stamp material. The previous work on the LMTP process focused on experimentally characterizing and modeling the effects of transferred inks’ sizes and thicknesses, and laser beam powers on the laser-driven delamination process mechanism. In this paper, several studies are conducted to understand the effects of other process parameters such as stamp post dimensions (size and height), PDMS formulation for the stamp, ink-stamp alignment, and the shape of the transferred silicon inks on the LMTP performance and mechanism. The studies are supported by both experimental data for the laser pulse duration required to initiate the delamination, and thermo-mechanical FEA model predictions of the energy stored at the interface’s edges to release the ink (Energy Release Rate (ERR)), stress levels at the delamination crack tip (Stress Intensity Factors (SIFs)), and interfacial temperature. This study, along with previous studies, should help LMTP users to understand the effects of the process parameters on the process performance so as to select optimal operation conditions.© 2014 ASME
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Characterization of Delamination in Laser Microtransfer Printing
Journal of Micro and Nano-Manufacturing, 2014Co-Authors: Ala'a M. Al-okaily, John A. Rogers, Placid M. FerreiraAbstract:Microtransfer printing is rapidly emerging as an effective method for heterogeneous materials integration. Laser microtransfer printing (LMTP) is a noncontact variant of the process that uses laser heating to drive the release of the microstructure from the stamp. This makes the process independent of the properties or preparation of the Receiving Substrate. In this paper, an extensive study is conducted to investigate the capability of the LMTP process. Furthermore, a thermomechanical finite element model (FEM) is developed, using the experimentally observed delamination times and absorbed powers, to estimate the delamination temperatures at the interface, as well as the strain, displacement, and thermal gradient fields.
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Characterization of Delamination in Laser Micro Transfer Printing
Volume 2A: Advanced Manufacturing, 2013Co-Authors: Ala'a M. Al-okaily, Placid M. FerreiraAbstract:Micro transfer printing is rapidly emerging as an effective method for heterogeneous materials integration. It transfers prefabricated micro- and nanoscale structures referred to as ‘inks’, from growth or fabrication donor Substrates to functional receiver Substrates. Laser Micro Transfer Printing (LMTP) is a laser-driven version of the micro transfer printing process, developed at the University of Illinois to enable non-contact release of the microstructure, thus making the transfer printing process independent of the properties or preparation of the Receiving Substrate. In this paper, an extensive study is conducted to investigate the capability of the LMTP process. Using square shaped silicon inks and polydimethylsiloxane (PDMS) stamps, and varying the lateral dimensions and thickness of the ink, the power absorption by the ink is measured to estimate the total energy stored in the ink-stamp system to initiate and propagate delamination at the interface. The delamination time for each size and thickness is experimentally observed at different laser beam powers using a high speed camera. Further, an axisymmetric thermo-mechanical FEM is developed to estimate the delamination temperatures at the interface utilizing the delamination time and power absorption for different ink sizes and thickness.Copyright © 2013 by ASME
