The Experts below are selected from a list of 1500 Experts worldwide ranked by ideXlab platform
Chingping Wong - One of the best experts on this subject based on the ideXlab platform.
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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.
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thermal conductivity enhancement of epoxy composites by interfacial covalent bonding for Underfill and thermal interfacial materials in cu low k application
IEEE Transactions on Components Packaging and Manufacturing Technology, 2012Co-Authors: Qizhe Liang, Kyoung-sik Moo, Hongji Jiang, Chingping WongAbstract:Nowadays with enhanced performance and reduced profile, electronics and photonics devices demand efficient heat dissipation and low operation temperature. Thereby, instead of traditional fillers (e.g., fused silica), thermally conductive silicon carbide (SiC) particles and multiwall carbon nanotubes (MWNTs) are applied here as fillers in composites for Underfill and thermal interfacial materials (TIMs), respectively. SiC particles are coated with an ultrathin layer of silicon oxide by thermal oxidation at 800°C in air and consequently functionalized by γ-glycidoxypropyl-trimethoxysilane in order to graft epoxides on their surface. Moreover, MWNTs were chemically functionalized with carboxyls and hydroxyls in a concentrated acid mixture. Transmission electron microscopy, Fourier-transform infrared spectrascopy, and thermogravimetric analysis characterization indicates that both of the fillers are successfully functionalized, which makes their surface reactive with epoxy resin, resulting in interfacial covalent chemical bonding between the thermally conductive fillers and epoxy resin. It is found that interfacial chemical bonding across the interface between these functionalized fillers and polymer matrix can promote significant thermal conductivity enhancement of epoxy composites, which is promising for Underfill and TIMs in Cu/low-K application.
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flip chip Underfill materials process and reliability
2009Co-Authors: Zhuqing Zhang, Chingping WongAbstract:In order to enhance the reliability of a flip-chip on organic board package, Underfill is usually used to redistribute the thermo-mechanical stress created by the Coefficient of Thermal Expansion (CTE) mismatch between the silicon chip and organic substrate. However, the conventional Underfill relies on the capillary flow of the Underfill material and has many disadvantages. In order to overcome these disadvantages, many variations have been invented to improve the flip-chip Underfill process. This paper reviews the recent advances in the material design, process development, and reliability issues of flip-chip Underfill, especially in no-flow Underfill, molded Underfill, and wafer-level Underfill. The relationship between the materials, process and reliability in these packages is discussed.
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void formation study of flip chip in package using no flow Underfill
IEEE Transactions on Electronics Packaging Manufacturing, 2008Co-Authors: Sangil Lee, Chingping Wong, Myung Ji Yim, Raj N Maste, Daniel F AldwiAbstract:The advanced flip chip in package (FCIP) process using no-flow Underfill material for high I/O density and fine-pitch interconnect applications presents challenges for an assembly process that must achieve high electrical interconnect yield and high reliability performance. With respect to high reliability, the voids formed in the Underfill between solder bumps or inside the solder bumps during the no-flow Underfill assembly process of FCIP devices have been typically considered one of the critical concerns affecting assembly yield and reliability performance. In this paper, the plausible causes of Underfill void formation in FCIP using no-flow Underfill were investigated through systematic experimentation with different types of test vehicles. For instance, the effects of process conditions, material properties, and chemical reaction between the solder bumps and no-flow Underfill materials on the void formation behaviors were investigated in advanced FCIP assemblies. In this investigation, the chemical reaction between solder and Underfill during the solder wetting and Underfill cure process has been found to be one of the most significant factors for void formation in high I/O and fine-pitch FCIP assembly using no-flow Underfill materials.
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room temperature stable Underfill with novel latent catalyst for wafer level flip chip packaging applications
Electronic Components and Technology Conference, 2006Co-Authors: Chingping WongAbstract:Imidazolium salts were explored as novel catalysts for Underfill application. The catalytic properties of a series of imidazolium salts with different coordinating anions were studied by a dynamic differential scanning calorimeter (DSC). By changing the counter anions in these catalysts, the curing kinetics of the Underfill can be adjusted. To understanding the curing mechanism of imidazolium salt, the thermal properties of these compounds were studied in terms of melting and decomposition temperatures. A possible reaction mechanism with these novel catalysts was proposed. One imidazolium salt was chosen as the catalyst for the Underfill and shelf-life experiments were conducted at room temperature (R.T.), as well as using common imidazole catalyst in a control sample. During the test, the viscosity of Underfill was measured by rheometer and the residue reaction heat of the Underfill curing was monitored by a DSC. The B-stage stability of this Underfill was also studied. With this novel catalyst, we have developed the RT stable epoxy resin based Underfills which also process good thermal stability after B-stage.
Antonello Astarita - One of the best experts on this subject based on the ideXlab platform.
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A new approach to study the influence of the weld bead morphology on the fatigue behaviour of Ti–6Al–4V laser beam-welded butt joints
The International Journal of Advanced Manufacturing Technology, 2017Co-Authors: Luca Boccarusso, Antonello Astarita, Giuseppe Arleo, Franco Bernardo, Piero Fazio, Massimo Durante, Fabrizio Memola Capece Minutolo, Raffaele Sepe, Antonino SquillaceAbstract:Ti–6Al–4V is an alloy increasingly used in aeronautics due to its high mechanical properties coupled with lightness. An effective technology used to manufacture titanium components with a reduced buy-to-fly ratio is laser beam welding. Previous studies showed that the key factor that rules the mechanical properties and the fatigue life of the joint is its morphology. The aims of this paper were to investigate the influence of the geometrical features of the joints (height of the top and root reinforcement, depth and radius of the Underfill, and the valley–valley Underfill distance) on their mechanical properties and also to conduct a finite element (FE) analysis on the real geometry of the welded joints. Ti–6Al–4V rolled sheets 3.2 mm thick were welded in butt joint configuration using a laser source and their performance was studied in terms of weld morphology, microstructure, Vickers microhardness and fatigue life. A full factorial plan, designed varying the welding speed and laser power, was carried out. The real geometry and then the joint morphology were studied through an innovative approach: for each specimen, both the total weld face and the total root surface were acquired using a confocal microscope. Finally, through these acquisitions, the clouds of points of the scanned surfaces were used in order to carry out a FE analysis capable of providing a stress concentration factor, K _ t , value for each detected joint. The main results are the realization of a reliable FE model by an experimental agreement and the relationship found amongst the fatigue performances and some noticeable metallurgical and geometrical features, such as the Underfill depth and the aspect ratio defined as the ratio between the maximum height of the joint and the valley–valley Underfill distance.
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effect of welding parameters on morphology and mechanical properties of ti 6al 4v laser beam welded butt joints
Journal of Materials Processing Technology, 2012Co-Authors: Antonino Squillace, Umberto Prisco, Sergio Ciliberto, Antonello AstaritaAbstract:Abstract The influence of welding speed and laser power on weld quality of 1.6 mm thick Ti − 6Al − 4V sheets autogenously laser beam welded in butt configuration using a Nd-YAG laser was studied. The joint quality was characterized in terms of weld morphology, microstructure and mechanical properties. An Underfill defect, controlling the whole weld geometry, was observed both at the weld face and root surface. In dependence of the specific heat input, this defect showed a maximum, which separates two different welding regimes: keyhole welding, at low heat input, and a welding regime where heat conduction around the keyhole is predominant, at high heat input. Influence of the Underfill radius on the weld fatigue life was also assessed.
Antonino Squillace - One of the best experts on this subject based on the ideXlab platform.
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A new approach to study the influence of the weld bead morphology on the fatigue behaviour of Ti–6Al–4V laser beam-welded butt joints
The International Journal of Advanced Manufacturing Technology, 2017Co-Authors: Luca Boccarusso, Antonello Astarita, Giuseppe Arleo, Franco Bernardo, Piero Fazio, Massimo Durante, Fabrizio Memola Capece Minutolo, Raffaele Sepe, Antonino SquillaceAbstract:Ti–6Al–4V is an alloy increasingly used in aeronautics due to its high mechanical properties coupled with lightness. An effective technology used to manufacture titanium components with a reduced buy-to-fly ratio is laser beam welding. Previous studies showed that the key factor that rules the mechanical properties and the fatigue life of the joint is its morphology. The aims of this paper were to investigate the influence of the geometrical features of the joints (height of the top and root reinforcement, depth and radius of the Underfill, and the valley–valley Underfill distance) on their mechanical properties and also to conduct a finite element (FE) analysis on the real geometry of the welded joints. Ti–6Al–4V rolled sheets 3.2 mm thick were welded in butt joint configuration using a laser source and their performance was studied in terms of weld morphology, microstructure, Vickers microhardness and fatigue life. A full factorial plan, designed varying the welding speed and laser power, was carried out. The real geometry and then the joint morphology were studied through an innovative approach: for each specimen, both the total weld face and the total root surface were acquired using a confocal microscope. Finally, through these acquisitions, the clouds of points of the scanned surfaces were used in order to carry out a FE analysis capable of providing a stress concentration factor, K _ t , value for each detected joint. The main results are the realization of a reliable FE model by an experimental agreement and the relationship found amongst the fatigue performances and some noticeable metallurgical and geometrical features, such as the Underfill depth and the aspect ratio defined as the ratio between the maximum height of the joint and the valley–valley Underfill distance.
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effect of welding parameters on morphology and mechanical properties of ti 6al 4v laser beam welded butt joints
Journal of Materials Processing Technology, 2012Co-Authors: Antonino Squillace, Umberto Prisco, Sergio Ciliberto, Antonello AstaritaAbstract:Abstract The influence of welding speed and laser power on weld quality of 1.6 mm thick Ti − 6Al − 4V sheets autogenously laser beam welded in butt configuration using a Nd-YAG laser was studied. The joint quality was characterized in terms of weld morphology, microstructure and mechanical properties. An Underfill defect, controlling the whole weld geometry, was observed both at the weld face and root surface. In dependence of the specific heat input, this defect showed a maximum, which separates two different welding regimes: keyhole welding, at low heat input, and a welding regime where heat conduction around the keyhole is predominant, at high heat input. Influence of the Underfill radius on the weld fatigue life was also assessed.
C.p. Wong - One of the best experts on this subject based on the ideXlab platform.
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Self-Patterning of Silica/Epoxy Nanocomposite Underfill by Tailored Hydrophilic-Superhydrophobic Surfaces for 3D Integrated Circuit (IC) Stacking
2017Co-Authors: Chia-chi Tua, Nathan Pataki James, Yu Che, Ya Liu, Kyoung-sik Moo, C.p. WongAbstract:As microelectronics are trending toward smaller packages and integrated circuit (IC) stacks nowadays, Underfill, the polymer composite filled in between the IC chip and the substrate, becomes increasingly important for interconnection reliability. However, traditional Underfills cannot meet the requirements for low-profile and fine pitch in high density IC stacking packages. Post-applied Underfills have difficulties in flowing into the small gaps between the chip and the substrate, while pre-applied Underfills face filler entrapment at bond pads. In this report, we present a self-patterning Underfilling technology that uses selective wetting of Underfill on Cu bond pads and Si3N4 passivation via surface energy engineering. This novel process, fully compatible with the conventional Underfilling process, eliminates the issue of filler entrapment in typical pre-applied Underfilling process, enabling high density and fine pitch IC die bonding
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Moisture Absorption in Uncured Underfill Materials
2016Co-Authors: Shijia Luo, C.p. WongAbstract:Abstract—This paper presents a systematic study on moisture absorption in uncured Underfill based on epoxy cured with acid anhydride [methylhexahydrophthalic anhydride (MHHPA)] and epoxy cured with non-acid anhydride curing agent. The influence of absorbed moisture on curing properties, thermomechanical property, and adhesion property of Underfill after curing has been investigated. For epoxy cured with non-acid anhydride, the moisture absorption is low, and the absorbed moisture has no significant effect on the properties of cured Underfill materials. For epoxy cured with acid anhydride, the moisture absorption before curing can be more than 2.0%, and the absorbed moisture can affect the properties significantly. The absorbed moisture can catalyze the curing reaction between acid anhydride and epoxy. The glass transition temperature of the cured samples is reduced after the Underfill absorbs the moisture before curing. The adhesion strength decreases dramatically after the Underfill absorbs the moisture before curing. Index Terms—Adhesion, epoxy, moisture absorption, Underfill. I
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design process and reliability of wafer level packaging
2007Co-Authors: Zhuqing Zhang, C.p. WongAbstract:Wafer level packaging (WLP) has been growing continuously in electronics packaging due to its low cost in batch manufacturing and the potential of enabling wafer test and burn-in. A variety of wafer level packages have been devised, among which four important categories are identified including thin film redistribution and bumping, encapsulated package, compliant interconnect, and wafer level Underfill. This chapter reviews the different WLP technologies with an emphasis on challenges and processes of the wafer level Underfill. The wafer level packaging integrated with wafer burn-in, test and module assembly shows great attraction due to the dramatic cost reduction. Cost effective ways of building wafer level test and burn-in are under investigation.
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study on mono dispersed nano size silica by surface modification for Underfill applications
Journal of Colloid and Interface Science, 2005Co-Authors: Zhuqing Zhang, C.p. WongAbstract:In order to improve the rheological behavior of the nanosilica composite no-flow Underfill, filler surface treatment using silane coupling agents was investigated to reduce the filler-filler interaction and to achieve the mono-dispersity of the nanosilica in the Underfill resin. The experimental conditions of the surface treatment were investigated in a design of experiment (DOE) in terms of the pre-treatment methods, coupling agent types, concentrations, and treatment durations. The particle dispersion after treatment was evaluated by the laser particle analyzer and the transmission electron microscopy (TEM). A mono-dispersed nanosilica solution in the polar medium was achieved using optimal experimental condition. The surface chemistry of the nanosilica was studied using Fourier transformed infrared spectroscopy (FTIR). The wettability of Underfill resin and water on the silane treated glass slides was studied using a goniometer. Based on the investigations, the silane-treated nanosilica fillers were incorporated into an Underfill resin to formulate a nanocomposite no-flow Underfill. It was found that the proper filler treatment could significantly reduce the viscosity of the nanocomposite.
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Effective elastic modulus of Underfill material for flip-chip applications
IEEE Transactions on Components and Packaging Technologies, 2002Co-Authors: Jianmin Qu, C.p. WongAbstract:In this paper, a micromechanics model based on the Mori-Tanaka method was developed to estimate the elastic modulus of Underfill materials. An explicit expression of the Underfill modulus was derived as a function of filler content and the properties of the matrix and the fillers. Predictions of the modulus from this theory were compared with experimentally measured values. Excellent agreement was observed.
Zhuqing Zhang - One of the best experts on this subject based on the ideXlab platform.
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flip chip Underfill materials process and reliability
2009Co-Authors: Zhuqing Zhang, Chingping WongAbstract:In order to enhance the reliability of a flip-chip on organic board package, Underfill is usually used to redistribute the thermo-mechanical stress created by the Coefficient of Thermal Expansion (CTE) mismatch between the silicon chip and organic substrate. However, the conventional Underfill relies on the capillary flow of the Underfill material and has many disadvantages. In order to overcome these disadvantages, many variations have been invented to improve the flip-chip Underfill process. This paper reviews the recent advances in the material design, process development, and reliability issues of flip-chip Underfill, especially in no-flow Underfill, molded Underfill, and wafer-level Underfill. The relationship between the materials, process and reliability in these packages is discussed.
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design process and reliability of wafer level packaging
2007Co-Authors: Zhuqing Zhang, C.p. WongAbstract:Wafer level packaging (WLP) has been growing continuously in electronics packaging due to its low cost in batch manufacturing and the potential of enabling wafer test and burn-in. A variety of wafer level packages have been devised, among which four important categories are identified including thin film redistribution and bumping, encapsulated package, compliant interconnect, and wafer level Underfill. This chapter reviews the different WLP technologies with an emphasis on challenges and processes of the wafer level Underfill. The wafer level packaging integrated with wafer burn-in, test and module assembly shows great attraction due to the dramatic cost reduction. Cost effective ways of building wafer level test and burn-in are under investigation.
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study and characterization on the nanocomposite Underfill for flip chip applications
IEEE Transactions on Components and Packaging Technologies, 2006Co-Authors: Zhuqing Zhang, Chingping WongAbstract:The nanosilica filled composite is a promising material for the no-flow Underfill in flip-chip application. However, as the filler size decreases into the nano length scale, the rheological, mechanical, and thermal mechanical properties of the composite change significantly. The filler-filler and filler-polymer interactions have a profound impact on the material properties. The purpose of this paper is to achieve an in-depth understanding of the effect of the filler size and surface treatment on material properties and therefore to design a nanocomposite formulation with desirable material properties for no-flow Underfill applications. Mono-dispersed nanosilica filler of 100nm in size were used in this study. An epoxy/anhydride mixture was used as the base resin formulation. The nanosilica fillers were incorporated into the resin mixture to different filler loadings from 5wt% to 40wt% with or without silane coupling agents as the surface treatment. UV-Visible spectroscopy showed that the Underfills with nano-size filler were transparent in the visible region even at high filler loading. The curing behavior and the Tg of the nanocomposite were studied using a modulated differential scanning calorimerter. It was found that the presence of the nanosilica could hinder the curing reaction, especially at the late stage of cure. The Tgs of the nanocomposites with untreated silica were found to decrease with the increasing filler loading. The measurement of the dynamic moduli from dynamic mechanical analyzer indicated that there was a secondary relaxation related to the filler-polymer interface. The coefficient of thermal expansion of the nanocomposite was measured using a thermal mechanical analyzer. The rheology of the nanocomposite was studied using a stress rheometer. It was found that the filler treatment could significantly reduce the viscosity of the nanocomposite and improve the processing capability of the Underfill. Density measurements and moisture absorption experiments both indicated that the addition of nanosilica could increase the free volume of materials. The dispersion of the nanosilica in the cured composite materials was observed using scanning electron microscopy. Control samples with micron-size silica fillers were formulated and characterized for comparison.
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study on mono dispersed nano size silica by surface modification for Underfill applications
Journal of Colloid and Interface Science, 2005Co-Authors: Zhuqing Zhang, C.p. WongAbstract:In order to improve the rheological behavior of the nanosilica composite no-flow Underfill, filler surface treatment using silane coupling agents was investigated to reduce the filler-filler interaction and to achieve the mono-dispersity of the nanosilica in the Underfill resin. The experimental conditions of the surface treatment were investigated in a design of experiment (DOE) in terms of the pre-treatment methods, coupling agent types, concentrations, and treatment durations. The particle dispersion after treatment was evaluated by the laser particle analyzer and the transmission electron microscopy (TEM). A mono-dispersed nanosilica solution in the polar medium was achieved using optimal experimental condition. The surface chemistry of the nanosilica was studied using Fourier transformed infrared spectroscopy (FTIR). The wettability of Underfill resin and water on the silane treated glass slides was studied using a goniometer. Based on the investigations, the silane-treated nanosilica fillers were incorporated into an Underfill resin to formulate a nanocomposite no-flow Underfill. It was found that the proper filler treatment could significantly reduce the viscosity of the nanocomposite.
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Recent advances in flip-chip Underfill: materials, process, and reliability
IEEE Transactions on Advanced Packaging, 2004Co-Authors: Zhuqing Zhang, Chingping WongAbstract:In order to enhance the reliability of a flip-chip on organic board package, Underfill is usually used to redistribute the thermomechanical stress created by the coefficient of thermal expansion (CTE) mismatch between the silicon chip and organic substrate. However, the conventional Underfill relies on the capillary flow of the Underfill resin and has many disadvantages. In order to overcome these disadvantages, many variations have been invented to improve the flip-chip Underfill process. This paper reviews the recent advances in the material design, process development, and reliability issues of flip-chip Underfill, especially in no-flow Underfill, molded Underfill, and wafer-level Underfill. The relationship between the materials, process, and reliability in these packages is discussed.
