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Papers by Gan Chong Leong

Research paper thumbnail of Specific Packaging Reliability Testing

Research paper thumbnail of Wearout Reliability-Based Characterization in Memory Packaging

Research paper thumbnail of Second Level Interconnect Reliability of Low Temperature Solder Materials Used in Memory Modules and Solid-State Drives (SSD)

Research paper thumbnail of Advanced Memory and Device Packaging

Research paper thumbnail of Recycling of Noble Metals Used in Memory Packaging

Springer series in reliability engineering, 2023

Research paper thumbnail of Reliability Simulation and Modeling in Memory Packaging

Springer series in reliability engineering, 2023

Research paper thumbnail of Interconnect Reliability in Advanced Memory Device Packaging

Research paper thumbnail of Interconnects Reliability for Future Cryogenic Memory Applications

Springer series in reliability engineering, 2023

Research paper thumbnail of Advanced Flip Chip Packaging

Research paper thumbnail of Correction: Comparative Reliability Studies and Analysis of Au, Pd-Coated Cu and Pd-Doped Cu Wire in Microelectronics Packaging

PLOS ONE, Jan 2, 2014

This paper compares and discusses the wearout reliability and analysis of Gold (Au), Palladium (P... more This paper compares and discusses the wearout reliability and analysis of Gold (Au), Palladium (Pd) coated Cu and Pd-doped Cu wires used in fineline Ball Grid Array (BGA) package. Intermetallic compound (IMC) thickness measurement has been carried out to estimate the coefficient of diffusion (D o) under various aging conditions of different bonding wires. Wire pull and ball bond shear strengths have been analyzed and we found smaller variation in Pd-doped Cu wire compared to Au and Pd-doped Cu wire. Au bonds were identified to have faster IMC formation, compared to slower IMC growth of Cu. The obtained weibull slope, b of three bonding wires are greater than 1.0 and belong to wearout reliability data point. Pd-doped Cu wire exhibits larger time-to-failure and cycles-to-failure in both wearout reliability tests in Highly Accelerated Temperature and Humidity (HAST) and Temperature Cycling (TC) tests. This proves Pd-doped Cu wire has a greater potential and higher reliability margin compared to Au and Pd-coated Cu wires.

Research paper thumbnail of Second Level Interconnect Reliability of Low Temperature Solder Materials Used in Memory Modules and Solid-State Drives (SSD)

Springer series in reliability engineering, 2023

Research paper thumbnail of Recycling of Noble Metals Used in Memory Packaging

Springer series in reliability engineering, 2023

Research paper thumbnail of Specific Packaging Reliability Testing

Springer series in reliability engineering, 2023

Research paper thumbnail of Recycling of Noble Metals Used in Memory Packaging

Springer Series in Reliability Engineering

Research paper thumbnail of A review of interconnect materials used in emerging memory device packaging: first- and second-level interconnect materials

Journal of Materials Science: Materials in Electronics, 2021

The main motivation of this review is to study the evolution of first and second level of interco... more The main motivation of this review is to study the evolution of first and second level of interconnect materials used in memory device semiconductor packaging. Evolutions of bonding wires from gold (Au) to silver (Ag) or copper (Cu) have been reported and studied in previous literatures for low-cost solution, but Au wire still gives highest rating in terms of the performance of temperature humidity test, high temperature storage, and bond-ability, etc. However, a new bonding wire material, Au-coated Ag, is recently developed to be an alternative solution which gives comparable performance, but lower cost compared to Au wire. In the first section of the article, the influence of a variety of factors were reviewed, which includes reliability performance and interfacial reaction that determines the performance of Au-coated Ag to reach for developing high reliability of bonded devices. With respect to second-level interconnects, SAC305 and SAC302 solder alloys give a balance performance between temperature cycling testing and drop testing, which are widely used in many field applications, such as mobile, consumer and computer. SAC405 and LF35 are developed for specific requirements such as SAC405 owns better temperature cycling performance, whereas LF35 gives excellent drop performance compared to SAC305 or SAC302. However, with market demands on automotive electronics get strong in recent years, solder joint reliability is being reviewed and discussed, especially in temperature cycling performance. Typical solder alloys on Ni/Au surface finish were not designed for automotive application to fulfill the requirement of board level reliability. Hence, newly developed solder alloys with Sn/Ag/Cu/Bi/Ni elements and Cu-OSP substrate surface finishes will be reviewed in the second section of the article.

Research paper thumbnail of Evolutions of bonding wires used in semiconductor electronics: perspective over 25 years

Journal of Materials Science: Materials in Electronics, 2015

The objective of this review is to study the evolution and key findings and critical technical ch... more The objective of this review is to study the evolution and key findings and critical technical challenges, solutions and future trend of bonding wires used in semiconductor electronics. Evolutions of bonding wires from Au to Cu and till the most recent silver (Ag) wire (perspective over 25 years packaging technology) have been discussed in this paper. The reliability performances of Au wire bonding, technical barriers of Cu wire bonding and corrosion mechanisms of Cu ball bonds are analyzed and covered. We focus on the influence of a variety of factors that have been reported recently, including reliability performance, wear out reliability performance that determine the selection of bonding wires to reach for developing high reliability of bonded devices. In the end of this review, the evolutions and future trends of bonding wires are compared and illustrated, which have marked effect based on the materials properties as well as reliability of wire types.

Research paper thumbnail of 100-Gbps 100-m Hollow-Core Fiber Optical Interconnection at 2-micron waveband by PS-DMT

Optical Fiber Communication Conference (OFC) 2020, 2020

2-Micron waveband optical interconnection at record-high-speed of 100 Gbps/lane with 100-m hollow... more 2-Micron waveband optical interconnection at record-high-speed of 100 Gbps/lane with 100-m hollow-core photonic bandgap fiber transmission is achieved. Mode-dependent bandwidth restriction is well optimized by probabilistically shaped discrete multi-tone (PS-DMT) modulation.

Research paper thumbnail of Experimental demonstration of 4 × 80-Gbit/s PAM-4 transmission over 8-km SSMF using Wiener filter

Electronics Letters, 2017

A 100-Gbit/s PAM-4 (pulse amplitude modulation) transmission over 4-km standard single-mode fibre... more A 100-Gbit/s PAM-4 (pulse amplitude modulation) transmission over 4-km standard single-mode fibre (SSMF) and a C-band 4 × 80-Gbit/s PAM-4 transmission over 8-km standard SSMF experimentally demonstrated. A digital Wiener filter (WF) at the receiver side is utilised to compensate the impairments introduced by the transmission link. Bit error rate below 7% forward error correction threshold (3.8 × 10−3) is achieved with received optical power of 0 dBm for the single lane 100-Gbit/s transmission and around −4 dBm for the four channels after 8-km transmission with WF, which is over one order of magnitude better than that without equalisation. The results indicate that WF is a good enough option for practical application in short reach optical interconnect.

Research paper thumbnail of Transmission of IM/DD Signals at 2 μm Wavelength Using PAM and CAP

IEEE Photonics Journal, 2016

Advanced modulation formats with intensity modulation and direct detection (IM/DD) have shown pro... more Advanced modulation formats with intensity modulation and direct detection (IM/DD) have shown promise in a short-reach optical communication system like data center interconnect. However, the conventional fiber transmission spectral window is mostly located at 850, 1310, and 1550 nm. Here, we experimentally demonstrated an amplifierless IM/DD link at the 2-μm spectral band. The signal is encoded with pulse amplitude modulation (PAM) and 3-D carrier-less amplitude and phase modulation (3-D-CAP). The encoded signal is transmitted through a 100 m-long solid-core fiber designed for single mode at 2-μm. We achieve a transmission with bit-rate of 40 Gbit/s using PAM-4 and 24 Gbit/s using CAP16. The measured bit error rates of both formats are below the forward error correction (FEC) limit of 3.8 × 10 −3. This study is the first demonstration of PAM4 and CAP transmission at 2-μm, and the results show a significant potential of advanced modulation for 2-μm optical communication.

Research paper thumbnail of Low-Latency and High-Speed Hollow-Core Fiber Optical Interconnection at 2-Micron Waveband

Journal of Lightwave Technology, 2020

Hollow-core fiber (HCF) has been attracting broad interests in recent decades, and has extended t... more Hollow-core fiber (HCF) has been attracting broad interests in recent decades, and has extended the communication window to longer wavelength, 2 micron. In this article, we present a demonstration of low-latency HCF short-reach optical interconnection at 2 micron, achieving a high single-lane speed of 100 Gbps. High physical speed (near vacuum-light-speed) and high information speed (100-Gbps) optical interconnection with 100-m transmission distance is experimentally achieved with error-free performance. Probabilistically shaped discrete multi-tone (PS-DMT) modulation with entropy loading is employed to accommodate the deteriorated frequency response caused by the mode dispersion in HCF. Compared with conventional solid-core fiber (SCF), HCF contributes 30.95% (1.5-μs per kilometer) latency reduction for the physical link. The system level latency reduction is 28% for 1-km interconnection distance (11% for 100-m), with respect to a microsecond-scale switching network for typical datacenter applications. This work substantially leaps over the 100G milestone of 2-micron HCF optical interconnection, and shows the potentiality with lower latency and further higher capacity.

Research paper thumbnail of Specific Packaging Reliability Testing

Research paper thumbnail of Wearout Reliability-Based Characterization in Memory Packaging

Research paper thumbnail of Second Level Interconnect Reliability of Low Temperature Solder Materials Used in Memory Modules and Solid-State Drives (SSD)

Research paper thumbnail of Advanced Memory and Device Packaging

Research paper thumbnail of Recycling of Noble Metals Used in Memory Packaging

Springer series in reliability engineering, 2023

Research paper thumbnail of Reliability Simulation and Modeling in Memory Packaging

Springer series in reliability engineering, 2023

Research paper thumbnail of Interconnect Reliability in Advanced Memory Device Packaging

Research paper thumbnail of Interconnects Reliability for Future Cryogenic Memory Applications

Springer series in reliability engineering, 2023

Research paper thumbnail of Advanced Flip Chip Packaging

Research paper thumbnail of Correction: Comparative Reliability Studies and Analysis of Au, Pd-Coated Cu and Pd-Doped Cu Wire in Microelectronics Packaging

PLOS ONE, Jan 2, 2014

This paper compares and discusses the wearout reliability and analysis of Gold (Au), Palladium (P... more This paper compares and discusses the wearout reliability and analysis of Gold (Au), Palladium (Pd) coated Cu and Pd-doped Cu wires used in fineline Ball Grid Array (BGA) package. Intermetallic compound (IMC) thickness measurement has been carried out to estimate the coefficient of diffusion (D o) under various aging conditions of different bonding wires. Wire pull and ball bond shear strengths have been analyzed and we found smaller variation in Pd-doped Cu wire compared to Au and Pd-doped Cu wire. Au bonds were identified to have faster IMC formation, compared to slower IMC growth of Cu. The obtained weibull slope, b of three bonding wires are greater than 1.0 and belong to wearout reliability data point. Pd-doped Cu wire exhibits larger time-to-failure and cycles-to-failure in both wearout reliability tests in Highly Accelerated Temperature and Humidity (HAST) and Temperature Cycling (TC) tests. This proves Pd-doped Cu wire has a greater potential and higher reliability margin compared to Au and Pd-coated Cu wires.

Research paper thumbnail of Second Level Interconnect Reliability of Low Temperature Solder Materials Used in Memory Modules and Solid-State Drives (SSD)

Springer series in reliability engineering, 2023

Research paper thumbnail of Recycling of Noble Metals Used in Memory Packaging

Springer series in reliability engineering, 2023

Research paper thumbnail of Specific Packaging Reliability Testing

Springer series in reliability engineering, 2023

Research paper thumbnail of Recycling of Noble Metals Used in Memory Packaging

Springer Series in Reliability Engineering

Research paper thumbnail of A review of interconnect materials used in emerging memory device packaging: first- and second-level interconnect materials

Journal of Materials Science: Materials in Electronics, 2021

The main motivation of this review is to study the evolution of first and second level of interco... more The main motivation of this review is to study the evolution of first and second level of interconnect materials used in memory device semiconductor packaging. Evolutions of bonding wires from gold (Au) to silver (Ag) or copper (Cu) have been reported and studied in previous literatures for low-cost solution, but Au wire still gives highest rating in terms of the performance of temperature humidity test, high temperature storage, and bond-ability, etc. However, a new bonding wire material, Au-coated Ag, is recently developed to be an alternative solution which gives comparable performance, but lower cost compared to Au wire. In the first section of the article, the influence of a variety of factors were reviewed, which includes reliability performance and interfacial reaction that determines the performance of Au-coated Ag to reach for developing high reliability of bonded devices. With respect to second-level interconnects, SAC305 and SAC302 solder alloys give a balance performance between temperature cycling testing and drop testing, which are widely used in many field applications, such as mobile, consumer and computer. SAC405 and LF35 are developed for specific requirements such as SAC405 owns better temperature cycling performance, whereas LF35 gives excellent drop performance compared to SAC305 or SAC302. However, with market demands on automotive electronics get strong in recent years, solder joint reliability is being reviewed and discussed, especially in temperature cycling performance. Typical solder alloys on Ni/Au surface finish were not designed for automotive application to fulfill the requirement of board level reliability. Hence, newly developed solder alloys with Sn/Ag/Cu/Bi/Ni elements and Cu-OSP substrate surface finishes will be reviewed in the second section of the article.

Research paper thumbnail of Evolutions of bonding wires used in semiconductor electronics: perspective over 25 years

Journal of Materials Science: Materials in Electronics, 2015

The objective of this review is to study the evolution and key findings and critical technical ch... more The objective of this review is to study the evolution and key findings and critical technical challenges, solutions and future trend of bonding wires used in semiconductor electronics. Evolutions of bonding wires from Au to Cu and till the most recent silver (Ag) wire (perspective over 25 years packaging technology) have been discussed in this paper. The reliability performances of Au wire bonding, technical barriers of Cu wire bonding and corrosion mechanisms of Cu ball bonds are analyzed and covered. We focus on the influence of a variety of factors that have been reported recently, including reliability performance, wear out reliability performance that determine the selection of bonding wires to reach for developing high reliability of bonded devices. In the end of this review, the evolutions and future trends of bonding wires are compared and illustrated, which have marked effect based on the materials properties as well as reliability of wire types.

Research paper thumbnail of 100-Gbps 100-m Hollow-Core Fiber Optical Interconnection at 2-micron waveband by PS-DMT

Optical Fiber Communication Conference (OFC) 2020, 2020

2-Micron waveband optical interconnection at record-high-speed of 100 Gbps/lane with 100-m hollow... more 2-Micron waveband optical interconnection at record-high-speed of 100 Gbps/lane with 100-m hollow-core photonic bandgap fiber transmission is achieved. Mode-dependent bandwidth restriction is well optimized by probabilistically shaped discrete multi-tone (PS-DMT) modulation.

Research paper thumbnail of Experimental demonstration of 4 × 80-Gbit/s PAM-4 transmission over 8-km SSMF using Wiener filter

Electronics Letters, 2017

A 100-Gbit/s PAM-4 (pulse amplitude modulation) transmission over 4-km standard single-mode fibre... more A 100-Gbit/s PAM-4 (pulse amplitude modulation) transmission over 4-km standard single-mode fibre (SSMF) and a C-band 4 × 80-Gbit/s PAM-4 transmission over 8-km standard SSMF experimentally demonstrated. A digital Wiener filter (WF) at the receiver side is utilised to compensate the impairments introduced by the transmission link. Bit error rate below 7% forward error correction threshold (3.8 × 10−3) is achieved with received optical power of 0 dBm for the single lane 100-Gbit/s transmission and around −4 dBm for the four channels after 8-km transmission with WF, which is over one order of magnitude better than that without equalisation. The results indicate that WF is a good enough option for practical application in short reach optical interconnect.

Research paper thumbnail of Transmission of IM/DD Signals at 2 μm Wavelength Using PAM and CAP

IEEE Photonics Journal, 2016

Advanced modulation formats with intensity modulation and direct detection (IM/DD) have shown pro... more Advanced modulation formats with intensity modulation and direct detection (IM/DD) have shown promise in a short-reach optical communication system like data center interconnect. However, the conventional fiber transmission spectral window is mostly located at 850, 1310, and 1550 nm. Here, we experimentally demonstrated an amplifierless IM/DD link at the 2-μm spectral band. The signal is encoded with pulse amplitude modulation (PAM) and 3-D carrier-less amplitude and phase modulation (3-D-CAP). The encoded signal is transmitted through a 100 m-long solid-core fiber designed for single mode at 2-μm. We achieve a transmission with bit-rate of 40 Gbit/s using PAM-4 and 24 Gbit/s using CAP16. The measured bit error rates of both formats are below the forward error correction (FEC) limit of 3.8 × 10 −3. This study is the first demonstration of PAM4 and CAP transmission at 2-μm, and the results show a significant potential of advanced modulation for 2-μm optical communication.

Research paper thumbnail of Low-Latency and High-Speed Hollow-Core Fiber Optical Interconnection at 2-Micron Waveband

Journal of Lightwave Technology, 2020

Hollow-core fiber (HCF) has been attracting broad interests in recent decades, and has extended t... more Hollow-core fiber (HCF) has been attracting broad interests in recent decades, and has extended the communication window to longer wavelength, 2 micron. In this article, we present a demonstration of low-latency HCF short-reach optical interconnection at 2 micron, achieving a high single-lane speed of 100 Gbps. High physical speed (near vacuum-light-speed) and high information speed (100-Gbps) optical interconnection with 100-m transmission distance is experimentally achieved with error-free performance. Probabilistically shaped discrete multi-tone (PS-DMT) modulation with entropy loading is employed to accommodate the deteriorated frequency response caused by the mode dispersion in HCF. Compared with conventional solid-core fiber (SCF), HCF contributes 30.95% (1.5-μs per kilometer) latency reduction for the physical link. The system level latency reduction is 28% for 1-km interconnection distance (11% for 100-m), with respect to a microsecond-scale switching network for typical datacenter applications. This work substantially leaps over the 100G milestone of 2-micron HCF optical interconnection, and shows the potentiality with lower latency and further higher capacity.

Research paper thumbnail of 2013 IEEE IMPACT Conference Agenda

Research paper thumbnail of Book Review: 3D Stacked Chips