Kyung-Wook Paik - Academia.edu (original) (raw)
Papers by Kyung-Wook Paik
Journal of Applied Physics, Nov 15, 1999
The thermomechanical behavior of multilayer structures is a subject of perennial interest. Stoney... more The thermomechanical behavior of multilayer structures is a subject of perennial interest. Stoney's formula has long been one of the most important tools for understanding thermomechanical stress for single-layered structures like spin-coated polyimides or deposited metal thin film on substrates. In today's microelectronics, however, as multilayer substrates have become widely available, the ''modified version'' of Stoney's formula for multilayer applications is not only useful but necessary. While the majority of reports in the literature have focused on single-layer analysis, in this study, we examined an extended usage of Stoney's formula for multilayer analysis. A simple model, the multilayer-modified Stoney's formula, which predicts the stress contribution of each individual layer is proposed and verified through experiments and numerical analysis. Using various kinds of materials employed in a typical lamination-based multichip module technology, the thermomechanical behavior of the lamination-based multilayer substrates was measured by a laser profilometry during thermal cycling. The measured values were compared with calculated values using the multilayer-modified Stoney's formula.
The present invention is an adhesive for facilitating bonding between the electronic component an... more The present invention is an adhesive for facilitating bonding between the electronic component and the functional fibers and the fiber aggregate to implement various functions, and relates to a method of manufacturing the same, particularly as a fiber that is formed extending in the longitudinal direction in accordance with the present invention, the carrier polymer ( carrier polymer) and a plurality of functional particles, and wherein the plurality of functional particles is characterized in that the integrated carrier is fixed to the polymer are physically enclosed in the carrier polymer.
Journal of Materials Science Materials in Electronics
MRS Proceedings, 1998
ABSTRACTThermo-mechanical stresses in MCM-D substrate are important reliability and fabrication i... more ABSTRACTThermo-mechanical stresses in MCM-D substrate are important reliability and fabrication issues. The differences in coefficient of thermal expansion (CTE) between substrate, polymer, and metal leads to complicated stress fields in multilevel interconnect structures. While the majority of reports in the literature have focused on spin-coated polyimides, this paper mainly focuses on laminated polymer dielectrics. This study uses material sets representing typical MCM-D structures to monitor the stress level in the polymer films. The substrate deflection caused by composite stresses during fabrication and thermal cycling test is determined by a curvature measurement technique. A simple analytical model which predicts a stress contribution from each individual layer during MCM-D substrate fabrication is proposed and developed by computer simulation as well. The composite stress or bowing in multilayer structures is due to the summation of each individual layer contribution. From ...
Journal of Applied Physics, 1999
The thermomechanical behavior of multilayer structures is a subject of perennial interest. Stoney... more The thermomechanical behavior of multilayer structures is a subject of perennial interest. Stoney’s formula has long been one of the most important tools for understanding thermomechanical stress for single-layered structures like spin-coated polyimides or deposited metal thin film on substrates. In today’s microelectronics, however, as multilayer substrates have become widely available, the “modified version” of Stoney’s formula for multilayer applications is not only useful but necessary. While the majority of reports in the literature have focused on single-layer analysis, in this study, we examined an extended usage of Stoney’s formula for multilayer analysis. A simple model, the multilayer-modified Stoney’s formula, which predicts the stress contribution of each individual layer is proposed and verified through experiments and numerical analysis. Using various kinds of materials employed in a typical lamination-based multichip module technology, the thermomechanical behavior of...
IEEE Transactions on Advanced Packaging, 1999
Applied Physics Letters, 1999
As an increasing number of polymer dielectric layers were laminated, the maximum bow values were ... more As an increasing number of polymer dielectric layers were laminated, the maximum bow values were measured layer by layer using a laser profilometry during thermal cycling. In the lamination process, a polymeric film is overlaid on a silicon substrate using a polymeric adhesive. Since the lamination process uses relatively thick polymer films, the classical stress analyses assuming infinitesimally thin films, are no longer effective. In this letter, a simple model based on the composite beam theory is presented to analyze the experimental results, and compared with the well-known Stoney’s formula. The thermomechanical behavior of the laminated multilayer polymer films on a silicon substrate was better described by the proposed model, while an error as much as 30% was involved using Stoney’s formula. The model can be applied for the design and fabrication of multilayer multichip module substrates.
52nd Electronic Components and Technology Conference 2002. (Cat. No.02CH37345), 2002
2001 Proceedings. 51st Electronic Components and Technology Conference (Cat. No.01CH37220), 2000
Although integral capacitors fabricated using polymer/ceramic composite film have been intensivel... more Although integral capacitors fabricated using polymer/ceramic composite film have been intensively investigated, there was no systematic study of relationships between suspension formulation and properties of capacitors made from the suspension. In this paper the effects of the suspension formulation such as powder size, amount of dispersant, and amount of solvent, on the capacitor properties such as dielectric constant, dielectric loss,
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2002
ABSTRACT
Advances in Electronic Materials and Packaging 2001 (Cat. No.01EX506), 2000
Flip chip assembly on organic substrates using ACAs have received much attention due to many adva... more Flip chip assembly on organic substrates using ACAs have received much attention due to many advantages such as easier processing, better electrical performance, lower cost, and lower temperature processing compatible with organic substrates. ACAs are generally composed of epoxy polymer resin and small amount of conductive fillers (less than 10 wt.%). As a result, ACAs have almost the same CTE values as an epoxy material itself which are higher than conventional underfill materials which contains lots of fillers. Therefore, it is necessary to lower the CTE value of ACAs to obtain more reliable flip chip assembly on organic substrates using ACAs. To modify the ACA composite materials with some amount of conductive fillers, non-conductive fillers were incorporated into ACAs.
Proceedings - Electronic Components and Technology Conference
ABSTRACT
2001 Proceedings. 51st Electronic Components and Technology Conference (Cat. No.01CH37220), 2001
The electroless deposited Ni-P(Phosphorus) under bump metallurgy (UBM) layer was fabricated for S... more The electroless deposited Ni-P(Phosphorus) under bump metallurgy (UBM) layer was fabricated for Sn containing solder bumps. The amount of P in the electroless Ni film was optimized by controlling complexing agents and the pH of plating solution. And the interfacial reaction at the electroless Ni UBM/solder interface was investigated in this work. The intermetallic compound(IMC) formed at the interface during solder reflowing was mainly Ni 3 Sn 4 , and a P-rich Ni layer was also formed as a by-product of Ni-Sn reaction between the Ni-Sn IMC and the electroless Ni layer. A 1~4 µm of Ni 3 Sn 4 IMC and a 1800~5000 Å of P-rich Ni layer were formed in less than 10 minutes of solder reflowing depending on solder materials and reflow temperatures. However, less than 1 m thickness of the electroless Ni layer was consumed. It was found that the P-rich Ni layer contains Ni, P and a small amount of Sn (~7 at%). The atomic ratio of 3Ni:1P indicates that there is Ni 3 P phase in the P-rich Ni layer which was verified by the X-ray analysis. And no Sn was detected at the electroless Ni layer located just below the P-rich Ni layer. Therefore, the P-rich Ni layer, a by-product layer of Ni-Sn interfacial reaction, is not appropriate for a Sn diffusion barrier at the electroless Ni UBM and Sn containing solders.
Journal of Electronic Materials, 2015
Nanofiber anisotropic conductive films (ACF) were invented, by adapting nanofiber technology to A... more Nanofiber anisotropic conductive films (ACF) were invented, by adapting nanofiber technology to ACF materials, to overcome the limitations of ultra-finepitch interconnection packaging, i.e. shorts and open circuits as a result of the narrow space between bumps and electrodes. For nanofiber ACF, poly(vinylidene fluoride) (PVDF) and poly(butylene succinate) (PBS) polymers were used as nanofiber polymer materials. For PVDF and PBS nanofiber ACF, conductive particles of diameter 3.5 lm were incorporated into nanofibers by electrospinning. In ultra-fine-pitch chip-on-glass assembly, insulation was significantly improved by using nanofiber ACF, because nanofibers inside the ACF suppressed the mobility of conductive particles, preventing them from flowing out during the bonding process. Capture of conductive particles was increased from 31% (conventional ACF) to 65%, and stable electrical properties and reliability were achieved by use of nanofiber ACF.
A novel process which combined wafer level package technology with ultra-fine pitch chip-on-flex ... more A novel process which combined wafer level package technology with ultra-fine pitch chip-on-flex (COF) by sidewall-insulated compliant bumps was developed. We laminated two types of adhesives, single-layer non-conductive adhesive (NCA) and double-layer of non-conductive adhesive/anisotropic conductive adhesive (NCA/ACA), on wafers, respectively. After wafers with laminated adhesives were diced into chips, thermo-compression bonding process was executed by using high accuracy flip-chip bonder. Proper bonding parameters, such as bonding temperature, time, and pressure, were performed during bonding process. Both mechanical and electrical tests were carried out to evaluate bonding quality of adhesive-bonded COFs. 90-degree of peeling test was conducted as mechanical test to evaluate adhesion of bonding interface. Measurements of electrical insulating resistance and 606 I/Os daisy chain resistance were conducted. The reliability of pre-applied adhesive COFs with 20 μm-pitch sidewall-ins...
2007 International Conference on Electronic Materials and Packaging, 2007
Electroless Ni-P plating is cost effective process to fabricate UBM for solder flip chip. Thickne... more Electroless Ni-P plating is cost effective process to fabricate UBM for solder flip chip. Thickness of electroless Ni-P UBM is important factor for mechanical and electromigration reliability. Pb-free solder flip chips with different UBM thicknesses of 3, 5 and 10 mum were prepared. First, the effect of UBM thickness on mechanical reliability was investigated. Before underfilling, flip chips using Pb-free solders and electroless Ni-P UBMs on organic substrates were prone to a brittle failure. As lowering the thickness of electroless Ni-P UBM, failure type of solder joints was changed from brittle to fatigue. Thin electroless Ni-P UBM was more effective to resist the thermal deformation during solder reflowing than thicker UBMs. Second, the effect of UBM thickness on electromogration reliability was investigated. As results of electromigration test, time to failure of the solder joint with 10 mum UBM increased about 3 times than that of the solder joint with 5 mum UBM. Time to failure increased due to the lowered current crowding effect at UBM/solder interface in the solder joint with thicker UBM.
A primary factor of ACF package failure is delamination between the chip and the adhesive at the ... more A primary factor of ACF package failure is delamination between the chip and the adhesive at the edge of the chip. This delamination is mainly affected by the normal strain at the edge of the chip. This normal strain was measured on various electronic ACF package specimens by micro Moireacute interferometry with a phase shifting method. In order to find
Journal of Applied Physics, Nov 15, 1999
The thermomechanical behavior of multilayer structures is a subject of perennial interest. Stoney... more The thermomechanical behavior of multilayer structures is a subject of perennial interest. Stoney's formula has long been one of the most important tools for understanding thermomechanical stress for single-layered structures like spin-coated polyimides or deposited metal thin film on substrates. In today's microelectronics, however, as multilayer substrates have become widely available, the ''modified version'' of Stoney's formula for multilayer applications is not only useful but necessary. While the majority of reports in the literature have focused on single-layer analysis, in this study, we examined an extended usage of Stoney's formula for multilayer analysis. A simple model, the multilayer-modified Stoney's formula, which predicts the stress contribution of each individual layer is proposed and verified through experiments and numerical analysis. Using various kinds of materials employed in a typical lamination-based multichip module technology, the thermomechanical behavior of the lamination-based multilayer substrates was measured by a laser profilometry during thermal cycling. The measured values were compared with calculated values using the multilayer-modified Stoney's formula.
The present invention is an adhesive for facilitating bonding between the electronic component an... more The present invention is an adhesive for facilitating bonding between the electronic component and the functional fibers and the fiber aggregate to implement various functions, and relates to a method of manufacturing the same, particularly as a fiber that is formed extending in the longitudinal direction in accordance with the present invention, the carrier polymer ( carrier polymer) and a plurality of functional particles, and wherein the plurality of functional particles is characterized in that the integrated carrier is fixed to the polymer are physically enclosed in the carrier polymer.
Journal of Materials Science Materials in Electronics
MRS Proceedings, 1998
ABSTRACTThermo-mechanical stresses in MCM-D substrate are important reliability and fabrication i... more ABSTRACTThermo-mechanical stresses in MCM-D substrate are important reliability and fabrication issues. The differences in coefficient of thermal expansion (CTE) between substrate, polymer, and metal leads to complicated stress fields in multilevel interconnect structures. While the majority of reports in the literature have focused on spin-coated polyimides, this paper mainly focuses on laminated polymer dielectrics. This study uses material sets representing typical MCM-D structures to monitor the stress level in the polymer films. The substrate deflection caused by composite stresses during fabrication and thermal cycling test is determined by a curvature measurement technique. A simple analytical model which predicts a stress contribution from each individual layer during MCM-D substrate fabrication is proposed and developed by computer simulation as well. The composite stress or bowing in multilayer structures is due to the summation of each individual layer contribution. From ...
Journal of Applied Physics, 1999
The thermomechanical behavior of multilayer structures is a subject of perennial interest. Stoney... more The thermomechanical behavior of multilayer structures is a subject of perennial interest. Stoney’s formula has long been one of the most important tools for understanding thermomechanical stress for single-layered structures like spin-coated polyimides or deposited metal thin film on substrates. In today’s microelectronics, however, as multilayer substrates have become widely available, the “modified version” of Stoney’s formula for multilayer applications is not only useful but necessary. While the majority of reports in the literature have focused on single-layer analysis, in this study, we examined an extended usage of Stoney’s formula for multilayer analysis. A simple model, the multilayer-modified Stoney’s formula, which predicts the stress contribution of each individual layer is proposed and verified through experiments and numerical analysis. Using various kinds of materials employed in a typical lamination-based multichip module technology, the thermomechanical behavior of...
IEEE Transactions on Advanced Packaging, 1999
Applied Physics Letters, 1999
As an increasing number of polymer dielectric layers were laminated, the maximum bow values were ... more As an increasing number of polymer dielectric layers were laminated, the maximum bow values were measured layer by layer using a laser profilometry during thermal cycling. In the lamination process, a polymeric film is overlaid on a silicon substrate using a polymeric adhesive. Since the lamination process uses relatively thick polymer films, the classical stress analyses assuming infinitesimally thin films, are no longer effective. In this letter, a simple model based on the composite beam theory is presented to analyze the experimental results, and compared with the well-known Stoney’s formula. The thermomechanical behavior of the laminated multilayer polymer films on a silicon substrate was better described by the proposed model, while an error as much as 30% was involved using Stoney’s formula. The model can be applied for the design and fabrication of multilayer multichip module substrates.
52nd Electronic Components and Technology Conference 2002. (Cat. No.02CH37345), 2002
2001 Proceedings. 51st Electronic Components and Technology Conference (Cat. No.01CH37220), 2000
Although integral capacitors fabricated using polymer/ceramic composite film have been intensivel... more Although integral capacitors fabricated using polymer/ceramic composite film have been intensively investigated, there was no systematic study of relationships between suspension formulation and properties of capacitors made from the suspension. In this paper the effects of the suspension formulation such as powder size, amount of dispersant, and amount of solvent, on the capacitor properties such as dielectric constant, dielectric loss,
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2002
ABSTRACT
Advances in Electronic Materials and Packaging 2001 (Cat. No.01EX506), 2000
Flip chip assembly on organic substrates using ACAs have received much attention due to many adva... more Flip chip assembly on organic substrates using ACAs have received much attention due to many advantages such as easier processing, better electrical performance, lower cost, and lower temperature processing compatible with organic substrates. ACAs are generally composed of epoxy polymer resin and small amount of conductive fillers (less than 10 wt.%). As a result, ACAs have almost the same CTE values as an epoxy material itself which are higher than conventional underfill materials which contains lots of fillers. Therefore, it is necessary to lower the CTE value of ACAs to obtain more reliable flip chip assembly on organic substrates using ACAs. To modify the ACA composite materials with some amount of conductive fillers, non-conductive fillers were incorporated into ACAs.
Proceedings - Electronic Components and Technology Conference
ABSTRACT
2001 Proceedings. 51st Electronic Components and Technology Conference (Cat. No.01CH37220), 2001
The electroless deposited Ni-P(Phosphorus) under bump metallurgy (UBM) layer was fabricated for S... more The electroless deposited Ni-P(Phosphorus) under bump metallurgy (UBM) layer was fabricated for Sn containing solder bumps. The amount of P in the electroless Ni film was optimized by controlling complexing agents and the pH of plating solution. And the interfacial reaction at the electroless Ni UBM/solder interface was investigated in this work. The intermetallic compound(IMC) formed at the interface during solder reflowing was mainly Ni 3 Sn 4 , and a P-rich Ni layer was also formed as a by-product of Ni-Sn reaction between the Ni-Sn IMC and the electroless Ni layer. A 1~4 µm of Ni 3 Sn 4 IMC and a 1800~5000 Å of P-rich Ni layer were formed in less than 10 minutes of solder reflowing depending on solder materials and reflow temperatures. However, less than 1 m thickness of the electroless Ni layer was consumed. It was found that the P-rich Ni layer contains Ni, P and a small amount of Sn (~7 at%). The atomic ratio of 3Ni:1P indicates that there is Ni 3 P phase in the P-rich Ni layer which was verified by the X-ray analysis. And no Sn was detected at the electroless Ni layer located just below the P-rich Ni layer. Therefore, the P-rich Ni layer, a by-product layer of Ni-Sn interfacial reaction, is not appropriate for a Sn diffusion barrier at the electroless Ni UBM and Sn containing solders.
Journal of Electronic Materials, 2015
Nanofiber anisotropic conductive films (ACF) were invented, by adapting nanofiber technology to A... more Nanofiber anisotropic conductive films (ACF) were invented, by adapting nanofiber technology to ACF materials, to overcome the limitations of ultra-finepitch interconnection packaging, i.e. shorts and open circuits as a result of the narrow space between bumps and electrodes. For nanofiber ACF, poly(vinylidene fluoride) (PVDF) and poly(butylene succinate) (PBS) polymers were used as nanofiber polymer materials. For PVDF and PBS nanofiber ACF, conductive particles of diameter 3.5 lm were incorporated into nanofibers by electrospinning. In ultra-fine-pitch chip-on-glass assembly, insulation was significantly improved by using nanofiber ACF, because nanofibers inside the ACF suppressed the mobility of conductive particles, preventing them from flowing out during the bonding process. Capture of conductive particles was increased from 31% (conventional ACF) to 65%, and stable electrical properties and reliability were achieved by use of nanofiber ACF.
A novel process which combined wafer level package technology with ultra-fine pitch chip-on-flex ... more A novel process which combined wafer level package technology with ultra-fine pitch chip-on-flex (COF) by sidewall-insulated compliant bumps was developed. We laminated two types of adhesives, single-layer non-conductive adhesive (NCA) and double-layer of non-conductive adhesive/anisotropic conductive adhesive (NCA/ACA), on wafers, respectively. After wafers with laminated adhesives were diced into chips, thermo-compression bonding process was executed by using high accuracy flip-chip bonder. Proper bonding parameters, such as bonding temperature, time, and pressure, were performed during bonding process. Both mechanical and electrical tests were carried out to evaluate bonding quality of adhesive-bonded COFs. 90-degree of peeling test was conducted as mechanical test to evaluate adhesion of bonding interface. Measurements of electrical insulating resistance and 606 I/Os daisy chain resistance were conducted. The reliability of pre-applied adhesive COFs with 20 μm-pitch sidewall-ins...
2007 International Conference on Electronic Materials and Packaging, 2007
Electroless Ni-P plating is cost effective process to fabricate UBM for solder flip chip. Thickne... more Electroless Ni-P plating is cost effective process to fabricate UBM for solder flip chip. Thickness of electroless Ni-P UBM is important factor for mechanical and electromigration reliability. Pb-free solder flip chips with different UBM thicknesses of 3, 5 and 10 mum were prepared. First, the effect of UBM thickness on mechanical reliability was investigated. Before underfilling, flip chips using Pb-free solders and electroless Ni-P UBMs on organic substrates were prone to a brittle failure. As lowering the thickness of electroless Ni-P UBM, failure type of solder joints was changed from brittle to fatigue. Thin electroless Ni-P UBM was more effective to resist the thermal deformation during solder reflowing than thicker UBMs. Second, the effect of UBM thickness on electromogration reliability was investigated. As results of electromigration test, time to failure of the solder joint with 10 mum UBM increased about 3 times than that of the solder joint with 5 mum UBM. Time to failure increased due to the lowered current crowding effect at UBM/solder interface in the solder joint with thicker UBM.
A primary factor of ACF package failure is delamination between the chip and the adhesive at the ... more A primary factor of ACF package failure is delamination between the chip and the adhesive at the edge of the chip. This delamination is mainly affected by the normal strain at the edge of the chip. This normal strain was measured on various electronic ACF package specimens by micro Moireacute interferometry with a phase shifting method. In order to find