The Experts below are selected from a list of 19935 Experts worldwide ranked by ideXlab platform
Chingping Wong - One of the best experts on this subject based on the ideXlab platform.
-
structure property relationships between microscopic Filler Surface chemistry and macroscopic rheological thermo mechanical and adhesive performance of sio2 filled nanocomposite underfills
Composites Part A-applied Science and Manufacturing, 2019Co-Authors: Tao Zhao, Chingping Wong, Pengli Zhu, Rong SunAbstract:Abstract SiO2 nanoparticles are attractive components for formulating highly filled underfill adhesives in the electronic packaging field. However, achieving uniform dispersion of inorganic SiO2 nanoparticles into an organic polymer matrix to obtain desired rheological and thermo-mechanical properties remains a significant challenge in nanocomposites engineering. To address the issue, previous studies mainly focused on tailoring the Filler morphology and size, volume fraction and Filler distribution. Here, in this work, in-situ modification of SiO2 nanoparticles by using organosilanes with different functional groups was conducted. We demonstrated the structure-property relationships between microscopic Surface state of SiO2 nanoFillers and macroscopic rheological, coefficient of thermal expansion (CTE) and adhesive properties of the resulting amine curing epoxy-based nanocomposite underfills. Our experimental results show that the modification of Filler Surface effectively enables the decrease of viscosity of underfill, and methacryl-terminated silane exhibits the highest efficiency among various organosilanes. Moreover, Surface modification improves the adhesion strength between the underfill and substrate evidently, and nonpolar groups function better than their polar counterparts. In addition, modification with nonpolar methacryloxy and phenyl groups is capable of reducing CTE of nanocomposites effectively while other groups have no significant contribution to CTE reduction. These properties improvement can be attributed to the alteration of interfacial compatibility and adhesion in the SiO2 nanocomposites. Overall, our work provides a useful guideline for the rational Surface chemistry design of SiO2 Filler and optimizing the overall performance of underfill adhesives.
-
tailored Surface chemistry of sio2 particles with improved rheological thermal mechanical and adhesive properties of epoxy based composites for underfill applications
Polymer, 2018Co-Authors: Pengli Zhu, Chingping Wong, Tao ZhaoAbstract:Abstract Recently, the silica particles filled epoxy-based composites underfill has gained more and more attentions with the development of flip chip technology towards high density and fine-pitch. However, serious agglomeration and poor dispersion of SiO2 in polymer matrix inevitably leads to deterioration of the rheological and thermal-mechanical properties. The Filler Surface treatment technology has been well demonstrated to be effective in controlling interfacial compatibility and interfacial interaction of their filled composites and thus enhancing their mechanical properties. However, the role of Surface characteristics of SiO2 Fillers on the properties associated with underfill such as rheological, coefficient of thermal expansion (CTE) as well as adhesive strength has been rarely reported. In this paper, Surface modification of SiO2 particles have been conducted using silane coupling agents with various functional groups. We have attempted to establish a qualitative structure-property relationship between microscopic Filler Surface chemistry and macroscopic properties of the resulting composites underfill. The results showed that Surface modification enabled to decrease underfill viscosity obviously and Surface modification with nonpolar groups, such as methacryloxy and phenyl groups showed a much higher efficiency for viscosity reduction than their polar groups counterparts, such as amino and epoxy groups. Meanwhile, underfill with these nonpolar groups modified SiO2 exhibited much higher adhesion strength, accompanied by a conversion of failure mode from the adhesive failure to cohesion failure. In contrast, Surface modification with those polar groups was more beneficial to decrease CTE of composites underfill. Our work is believed to be of great value for the design of SiO2 particle-based composites underfill with tailored properties.
-
Surface modification of nano size sio 2 Filler for flip chip underfill applications
International Conference on Electronic Packaging Technology, 2017Co-Authors: Pengli Zhu, Tao Zhao, Rong Sun, Chingping WongAbstract:Nano-sized spherical SiO 2 -filled polymer-based underfill play an important role in improving the reliability of high-density flip-chip packaging. However, how to allow extremely high Filler loading while maintaining a low viscosity and meanwhile how to achieve desired coefficient of thermal expansion (CTE) with lower Filler loading are two major challenges due to the serious agglomeration of nanoFillers in the polymer matrix. Currently, the study on rheological and thermal expansion behavior of composites mainly focuses on the effect of morphology, content, size and distribution of Fillers, while is relatively few from the aspects of Filler Surface design and interface tailoring of nanocomposite. Therefore, in our work, we attempt to conduct Surface modification of SiO 2 nanoFiller with Bis-F epoxy resin and systematically investigate the effect of Surface chemistry of Filler on the rheological and thermal expansion properties. The results showed that using Bis-F modified SiO 2 as Fillers, the viscosity of amine system was decreased, while the anhydride system increased, which was probably due to the competition ability between two factors associated with the improved compatibility and increased reactivity. However, there was no obvious contribution to the CTE reduction from Filler Surface modification, which probably due to the low grafting density of epoxy on the Filler. Therefore, how to rationally design Surface of nanoFiller and further optimization of a comprehensive performance of polymer based packaging materials should be carefully considered in future work.
-
silver Surface iodination for enhancing the conductivity of conductive composites
Advanced Functional Materials, 2010Co-Authors: Cheng Yang, Matthew Ming Fai Yuen, Bing Xu, Xiaomin Xiong, Chingping WongAbstract:The electrical conductivity of a silver microflake-filled conductive composites is dramatically improved after a Filler Surface treatment. By a simple iodine solution treatment, nonstoichiometric silver/silver iodide nanoislands form on the silver Filler Surface. Evidence of the decrease of Surface silver oxide species is provided by TOF-SIMS and the redox property of the nanoclusters is studied using cyclic voltammetry and TOF-SIMS depth profile analyses. The redox property of the nanoclusters on silver flakes helps enhance the electrical conductivity of the conductive composites. The electrical resistivity of the improved conductive composites is measured by four-point probe method; the reliability of the printed thin film resistors is evaluated by both the 85 °C/85% relative humidity moisture exposure and the −40 ∼ 125 °C thermal cycling exposure. The conductive composite printed radio frequency identification (RFID) antennas with 27.5 wt% of the modified silver flake content show comparable performance in the RFID tag read range versus copper foil antennas, and better than those commercial conductive adhesives that require much higher silver content (i.e., 80 wt%). This work suggests that a Surface chemistry method can significantly reduce the percolation threshold of the loading level of the silver flakes and improve the electrical conductivity of an important printed electronic passive component.
Pengli Zhu - One of the best experts on this subject based on the ideXlab platform.
-
structure property relationships between microscopic Filler Surface chemistry and macroscopic rheological thermo mechanical and adhesive performance of sio2 filled nanocomposite underfills
Composites Part A-applied Science and Manufacturing, 2019Co-Authors: Tao Zhao, Chingping Wong, Pengli Zhu, Rong SunAbstract:Abstract SiO2 nanoparticles are attractive components for formulating highly filled underfill adhesives in the electronic packaging field. However, achieving uniform dispersion of inorganic SiO2 nanoparticles into an organic polymer matrix to obtain desired rheological and thermo-mechanical properties remains a significant challenge in nanocomposites engineering. To address the issue, previous studies mainly focused on tailoring the Filler morphology and size, volume fraction and Filler distribution. Here, in this work, in-situ modification of SiO2 nanoparticles by using organosilanes with different functional groups was conducted. We demonstrated the structure-property relationships between microscopic Surface state of SiO2 nanoFillers and macroscopic rheological, coefficient of thermal expansion (CTE) and adhesive properties of the resulting amine curing epoxy-based nanocomposite underfills. Our experimental results show that the modification of Filler Surface effectively enables the decrease of viscosity of underfill, and methacryl-terminated silane exhibits the highest efficiency among various organosilanes. Moreover, Surface modification improves the adhesion strength between the underfill and substrate evidently, and nonpolar groups function better than their polar counterparts. In addition, modification with nonpolar methacryloxy and phenyl groups is capable of reducing CTE of nanocomposites effectively while other groups have no significant contribution to CTE reduction. These properties improvement can be attributed to the alteration of interfacial compatibility and adhesion in the SiO2 nanocomposites. Overall, our work provides a useful guideline for the rational Surface chemistry design of SiO2 Filler and optimizing the overall performance of underfill adhesives.
-
tailored Surface chemistry of sio2 particles with improved rheological thermal mechanical and adhesive properties of epoxy based composites for underfill applications
Polymer, 2018Co-Authors: Pengli Zhu, Chingping Wong, Tao ZhaoAbstract:Abstract Recently, the silica particles filled epoxy-based composites underfill has gained more and more attentions with the development of flip chip technology towards high density and fine-pitch. However, serious agglomeration and poor dispersion of SiO2 in polymer matrix inevitably leads to deterioration of the rheological and thermal-mechanical properties. The Filler Surface treatment technology has been well demonstrated to be effective in controlling interfacial compatibility and interfacial interaction of their filled composites and thus enhancing their mechanical properties. However, the role of Surface characteristics of SiO2 Fillers on the properties associated with underfill such as rheological, coefficient of thermal expansion (CTE) as well as adhesive strength has been rarely reported. In this paper, Surface modification of SiO2 particles have been conducted using silane coupling agents with various functional groups. We have attempted to establish a qualitative structure-property relationship between microscopic Filler Surface chemistry and macroscopic properties of the resulting composites underfill. The results showed that Surface modification enabled to decrease underfill viscosity obviously and Surface modification with nonpolar groups, such as methacryloxy and phenyl groups showed a much higher efficiency for viscosity reduction than their polar groups counterparts, such as amino and epoxy groups. Meanwhile, underfill with these nonpolar groups modified SiO2 exhibited much higher adhesion strength, accompanied by a conversion of failure mode from the adhesive failure to cohesion failure. In contrast, Surface modification with those polar groups was more beneficial to decrease CTE of composites underfill. Our work is believed to be of great value for the design of SiO2 particle-based composites underfill with tailored properties.
-
Surface modification of nano size sio 2 Filler for flip chip underfill applications
International Conference on Electronic Packaging Technology, 2017Co-Authors: Pengli Zhu, Tao Zhao, Rong Sun, Chingping WongAbstract:Nano-sized spherical SiO 2 -filled polymer-based underfill play an important role in improving the reliability of high-density flip-chip packaging. However, how to allow extremely high Filler loading while maintaining a low viscosity and meanwhile how to achieve desired coefficient of thermal expansion (CTE) with lower Filler loading are two major challenges due to the serious agglomeration of nanoFillers in the polymer matrix. Currently, the study on rheological and thermal expansion behavior of composites mainly focuses on the effect of morphology, content, size and distribution of Fillers, while is relatively few from the aspects of Filler Surface design and interface tailoring of nanocomposite. Therefore, in our work, we attempt to conduct Surface modification of SiO 2 nanoFiller with Bis-F epoxy resin and systematically investigate the effect of Surface chemistry of Filler on the rheological and thermal expansion properties. The results showed that using Bis-F modified SiO 2 as Fillers, the viscosity of amine system was decreased, while the anhydride system increased, which was probably due to the competition ability between two factors associated with the improved compatibility and increased reactivity. However, there was no obvious contribution to the CTE reduction from Filler Surface modification, which probably due to the low grafting density of epoxy on the Filler. Therefore, how to rationally design Surface of nanoFiller and further optimization of a comprehensive performance of polymer based packaging materials should be carefully considered in future work.
Tao Zhao - One of the best experts on this subject based on the ideXlab platform.
-
structure property relationships between microscopic Filler Surface chemistry and macroscopic rheological thermo mechanical and adhesive performance of sio2 filled nanocomposite underfills
Composites Part A-applied Science and Manufacturing, 2019Co-Authors: Tao Zhao, Chingping Wong, Pengli Zhu, Rong SunAbstract:Abstract SiO2 nanoparticles are attractive components for formulating highly filled underfill adhesives in the electronic packaging field. However, achieving uniform dispersion of inorganic SiO2 nanoparticles into an organic polymer matrix to obtain desired rheological and thermo-mechanical properties remains a significant challenge in nanocomposites engineering. To address the issue, previous studies mainly focused on tailoring the Filler morphology and size, volume fraction and Filler distribution. Here, in this work, in-situ modification of SiO2 nanoparticles by using organosilanes with different functional groups was conducted. We demonstrated the structure-property relationships between microscopic Surface state of SiO2 nanoFillers and macroscopic rheological, coefficient of thermal expansion (CTE) and adhesive properties of the resulting amine curing epoxy-based nanocomposite underfills. Our experimental results show that the modification of Filler Surface effectively enables the decrease of viscosity of underfill, and methacryl-terminated silane exhibits the highest efficiency among various organosilanes. Moreover, Surface modification improves the adhesion strength between the underfill and substrate evidently, and nonpolar groups function better than their polar counterparts. In addition, modification with nonpolar methacryloxy and phenyl groups is capable of reducing CTE of nanocomposites effectively while other groups have no significant contribution to CTE reduction. These properties improvement can be attributed to the alteration of interfacial compatibility and adhesion in the SiO2 nanocomposites. Overall, our work provides a useful guideline for the rational Surface chemistry design of SiO2 Filler and optimizing the overall performance of underfill adhesives.
-
tailored Surface chemistry of sio2 particles with improved rheological thermal mechanical and adhesive properties of epoxy based composites for underfill applications
Polymer, 2018Co-Authors: Pengli Zhu, Chingping Wong, Tao ZhaoAbstract:Abstract Recently, the silica particles filled epoxy-based composites underfill has gained more and more attentions with the development of flip chip technology towards high density and fine-pitch. However, serious agglomeration and poor dispersion of SiO2 in polymer matrix inevitably leads to deterioration of the rheological and thermal-mechanical properties. The Filler Surface treatment technology has been well demonstrated to be effective in controlling interfacial compatibility and interfacial interaction of their filled composites and thus enhancing their mechanical properties. However, the role of Surface characteristics of SiO2 Fillers on the properties associated with underfill such as rheological, coefficient of thermal expansion (CTE) as well as adhesive strength has been rarely reported. In this paper, Surface modification of SiO2 particles have been conducted using silane coupling agents with various functional groups. We have attempted to establish a qualitative structure-property relationship between microscopic Filler Surface chemistry and macroscopic properties of the resulting composites underfill. The results showed that Surface modification enabled to decrease underfill viscosity obviously and Surface modification with nonpolar groups, such as methacryloxy and phenyl groups showed a much higher efficiency for viscosity reduction than their polar groups counterparts, such as amino and epoxy groups. Meanwhile, underfill with these nonpolar groups modified SiO2 exhibited much higher adhesion strength, accompanied by a conversion of failure mode from the adhesive failure to cohesion failure. In contrast, Surface modification with those polar groups was more beneficial to decrease CTE of composites underfill. Our work is believed to be of great value for the design of SiO2 particle-based composites underfill with tailored properties.
-
Surface modification of nano size sio 2 Filler for flip chip underfill applications
International Conference on Electronic Packaging Technology, 2017Co-Authors: Pengli Zhu, Tao Zhao, Rong Sun, Chingping WongAbstract:Nano-sized spherical SiO 2 -filled polymer-based underfill play an important role in improving the reliability of high-density flip-chip packaging. However, how to allow extremely high Filler loading while maintaining a low viscosity and meanwhile how to achieve desired coefficient of thermal expansion (CTE) with lower Filler loading are two major challenges due to the serious agglomeration of nanoFillers in the polymer matrix. Currently, the study on rheological and thermal expansion behavior of composites mainly focuses on the effect of morphology, content, size and distribution of Fillers, while is relatively few from the aspects of Filler Surface design and interface tailoring of nanocomposite. Therefore, in our work, we attempt to conduct Surface modification of SiO 2 nanoFiller with Bis-F epoxy resin and systematically investigate the effect of Surface chemistry of Filler on the rheological and thermal expansion properties. The results showed that using Bis-F modified SiO 2 as Fillers, the viscosity of amine system was decreased, while the anhydride system increased, which was probably due to the competition ability between two factors associated with the improved compatibility and increased reactivity. However, there was no obvious contribution to the CTE reduction from Filler Surface modification, which probably due to the low grafting density of epoxy on the Filler. Therefore, how to rationally design Surface of nanoFiller and further optimization of a comprehensive performance of polymer based packaging materials should be carefully considered in future work.
Gert Heinrich - One of the best experts on this subject based on the ideXlab platform.
-
Location of dispersing agent in rubber nanocomposites during mixing process
Polymer, 2013Co-Authors: K. Oßwald, Sven Wießner, Amit Kumar Das, Klaus Werner Stöckelhuber, Regine Boldt, Gaurav Gupta, Gert Heinrich, H.-j. RaduschAbstract:Abstract In the present work, the development of morphology and selective wetting of nanoclay and carbon nanotubes (CNTs) in rubber nanocomposites were characterized qualitatively by means of the optical microscopy, TEM and AFM and quantitatively by means of the wetting concept . Carboxylated hydrogenated nitrile butadiene rubber (XHNBR), ionic liquid and ethanol were used as dispersing agent and they show very good effect on the macro- and microdispersion of nanoFillers in different rubbers. It was found that the selective wetting of Filler Surface by the dispersing agent and rubber matrix is controlled by thermodynamic and kinetic factors. A model basing on Surface energy data of polymer components (rubber and dispersing agent) and Filler was introduced in order to determine the thermodynamic equilibrium state of Filler wetting, which is found to be simultaneously determined by the Filler–polymer affinity and the rubber/dispersing agent mass ratio. During the mixing process a replacement process of bound polymer components takes place on the Filler Surface until the predicted state is reached.
-
impact of Filler Surface modification on large scale mechanics of styrene butadiene silica rubber composites
Macromolecules, 2011Co-Authors: Klaus Werner Stöckelhuber, A S Svistkov, A Pelevin, Gert HeinrichAbstract:In material science of elastomers the influence of nanoscale and nanostructured Filler particles is of utmost significance for the performance of innovative rubber products, i.e., passenger car tires with ultralow rolling resistance but high wet-grip performance. A better understanding of the physical characteristics of the Filler–rubber interface and the Filler–rubber interphase as well is necessary to improve the overall macroscopic properties of these elastomeric nanocomposites. Therefore, the Surface energies and polarities of Filler particles with different modified Surfaces were measured by a modified Wilhelmy technique. In all cases the rubber matrix consisted of a solution - styrene butadiene copolymers, filled with 20 or 40 phr pyrogenic or precipitated silica grades with different Surface modifications by silanes, and a carbon black sample as reference. A moving die rheometer was employed to observe the Filler flocculation at elevated temperatures (160 °C) in rubber mixtures containing no curati...
-
Modeling of the formation of oriented-polymer layers at Filler particles in polymer nanocomposites
Polymer Science Series A, 2008Co-Authors: A. L. Svistkov, Gert Heinrich, Lyudmila A. Komar, B. LaukeAbstract:A theory to explain the appearance of oriented layers at the Filler Surface in polymer nanocomposites is proposed. The theory is based on the assumption that small oriented polymer regions have an effect on the state of neighboring regions and tend to orient polymer chains in these regions. As a result, the point-to-point transfer of this effect takes place, thereby causing the propagation of the oriented layer in the polymer nanocomposite over a considerable distance from the Filler Surface. The appearance of the polymer in the biaxially oriented state, which is transferred to the neighboring regions and leads to the formation of a layer with specific mechanical properties, is possible near the Filler particles in this case.
John M. Torkelson - One of the best experts on this subject based on the ideXlab platform.
-
Reprocessable Polyhydroxyurethane Network Composites: Effect of Filler Surface Functionality on Cross-link Density Recovery and Stress Relaxation.
ACS Applied Materials & Interfaces, 2018Co-Authors: Xi Chen, Tong Wei, David C. Venerus, John M. TorkelsonAbstract:Conventional polymer network composites cannot be recycled for high-value applications because of the presence of permanent covalent cross-links. We have developed reprocessable polyhydroxyurethane network nanocomposites using silica nanoparticles with different Surface functionalities as reinforcing Fillers. The property recovery after reprocessing is a function of the interaction between the Filler Surface and the network matrix during the network rearrangement process. When nonreactive silica nanoparticles lacking significant levels of Surface functional groups are used at 4 wt % (2 vol %) loading, the resulting network composite exhibits substantial enhancement in mechanical properties relative to the neat network and based on values of rubbery plateau modulus is able to fully recover its cross-link density after a reprocessing step. When nanoparticles have Surface functional groups that can participate in dynamic chemistries with the reprocessable network matrix, reprocessing leads to losses in mecha...
-
importance of superior dispersion versus Filler Surface modification in producing robust polymer nanocomposites the example of polypropylene nanosilica hybrids
Polymer, 2015Co-Authors: Krishnan A. Iyer, John M. TorkelsonAbstract:Abstract With polymer nanocomposites, achieving highly effective dispersion of agglomerated nanoFiller and major or optimal property enhancements remain challenges. A commonly posited solution is to improve the polymer-Filler Surface thermodynamic compatibility; this approach has led to significant improvements in some cases, but it has not provided a general solution. We address the question of whether achieving a metastable, well-dispersed state is better than compatibilization in attaining the goal of major property enhancements. We use solid-state shear pulverization to produce well-dispersed polypropylene (PP) nanocomposites with up to 8 or 9 wt% pristine nanosilica ( p -NS) or organically modified nanosilica ( m -NS). Microscopy shows that as-received, tens-of-micron-sized p -NS and m -NS agglomerates undergo very good dispersion, with ∼10–100 nm size-range nanoFiller in hybrids. Rheology is consistent with very good dispersion, with only 92/8 wt% PP/ p -NS indicating incipient nanoFiller network formation. The PP/ p -NS hybrids have superior Young's modulus and tensile strength. Relative to PP, modulus increases by 22% and 12% and tensile strength by 19% and 14% for 99/1 wt% PP/ p -NS and 99/1 wt% PP/ m -NS, respectively. The PP/ p -NS hybrids have the largest increases in modulus (46% at 8 wt% p -NS) and tensile strength (22% at 6 wt% p -NS). Upon melting and crystallization, both PP/ p -NS and PP/ m -NS result in PP β-crystal formation at 1 wt% nanosilica, with p -NS having a greater effect. The PP/ p -NS hybrid shows larger increases in thermal stability and nucleating efficiency for PP crystallization. Thus, with very good dispersion, unmodified nanoFiller in a metastable dispersed state can result in more robust nanocomposites than when modified nanoFiller is used to compatibilize the polymer–nanoFiller interface.
-
Importance of superior dispersion versus Filler Surface modification in producing robust polymer nanocomposites: The example of polypropylene/nanosilica hybrids
Polymer, 2015Co-Authors: Krishnan A. Iyer, John M. TorkelsonAbstract:Abstract With polymer nanocomposites, achieving highly effective dispersion of agglomerated nanoFiller and major or optimal property enhancements remain challenges. A commonly posited solution is to improve the polymer-Filler Surface thermodynamic compatibility; this approach has led to significant improvements in some cases, but it has not provided a general solution. We address the question of whether achieving a metastable, well-dispersed state is better than compatibilization in attaining the goal of major property enhancements. We use solid-state shear pulverization to produce well-dispersed polypropylene (PP) nanocomposites with up to 8 or 9 wt% pristine nanosilica ( p -NS) or organically modified nanosilica ( m -NS). Microscopy shows that as-received, tens-of-micron-sized p -NS and m -NS agglomerates undergo very good dispersion, with ∼10–100 nm size-range nanoFiller in hybrids. Rheology is consistent with very good dispersion, with only 92/8 wt% PP/ p -NS indicating incipient nanoFiller network formation. The PP/ p -NS hybrids have superior Young's modulus and tensile strength. Relative to PP, modulus increases by 22% and 12% and tensile strength by 19% and 14% for 99/1 wt% PP/ p -NS and 99/1 wt% PP/ m -NS, respectively. The PP/ p -NS hybrids have the largest increases in modulus (46% at 8 wt% p -NS) and tensile strength (22% at 6 wt% p -NS). Upon melting and crystallization, both PP/ p -NS and PP/ m -NS result in PP β-crystal formation at 1 wt% nanosilica, with p -NS having a greater effect. The PP/ p -NS hybrid shows larger increases in thermal stability and nucleating efficiency for PP crystallization. Thus, with very good dispersion, unmodified nanoFiller in a metastable dispersed state can result in more robust nanocomposites than when modified nanoFiller is used to compatibilize the polymer–nanoFiller interface.