The aim of this study was to develop a flexible package technology using laser-assisted bonding (LAB) technology and an anisotropic solder paste (ASP) material ultimately to reduce the bonding temperature and enhance the flexibility and reliability of flexible devices. The heat transfer phenomena during the LAB process, mechanical deformation, and the flexibility of a flexible package were analyzed by experimental and numerical simulation methods. The flexible package was fabricated with a silicon chip and a polyimide (PI) substrate. When the laser beam was irradiated onto the flexible package, the temperatures of the solder increased very rapidly to 220 °C, high enough to melt the ASP solder, within 2.4 s. After the completion of irradiation, the temperature of the flexible package decreased quickly. It was found that the solder powder in ASP was completely melted and formed stable interconnections between the silicon chip and the copper pads, without thermal damage to the PI substrate. After the LAB process, the flexible package showed warpage of 80 μm, which was very small compared to the size of the flexible package. The stress of each component in the flexible package generated during the LAB process was also found to be very low. The flexible device was bent up to 7 mm without failure, and the flexibility can be improved further by reducing the thickness of the silicon chip. The bonding strength and environmental reliability tests also showed the excellent mechanical endurance of the flexible package.

An epoxy-based solder paste (ESP) is a promising alternative to conventional solder pastes to improve the reliability of fine-pitch electrical joining because the epoxy encapsulates the solder joint. However, development of an appropriate epoxy formulation and investigation of its reaction mechanism with solder powder is challenging. In this study, we demonstrate a newly designed ESP consisting of diglycidyl ether of bisphenol F (DGEBF) resin, Sn-3.0 Ag-0.5 Cu (SAC305) solder powder, and L-glutamic acid (Glu), which is a proteinogenic amino acid for biosynthesis of proteins in living systems. The mechanism of the thermochemical reaction was explored and tentatively proposed, which reveals that the products of the reaction between SAC305 and Glu function as catalysts for the etherification of epoxides and alcohols produced by chemical bonding between DGEBF and Glu, consequently leading to highly crosslinked polymeric networks and an enhancement of impact resistance. Our findings provide further insight into the mechanism of the reaction between various formulations comprising an epoxy, amino acid, and solder powder, and their potential use as ESPs for electrical joining.

We present a silicon nitride (SixNy) arrayed waveguide grating (AWG). Crosstalk in this AWG was reduced by decreasing the phase error in a multimode arrayed waveguide (WG) at center wavelength of 838 nm. 8-channel SixNy AWGs with double-etched inverse-tapered WG structure and cross-sectional area of 1.5 ×1.5 µm2 were fabricated from arrayed WGs. The AWG exhibited less than.29.6 dB crosstalk with 0.43 dB insertion loss for transverse electric (TE) polarization.

This brief presents a clocked pluggable optics suitable for high-density data center interconnections. The proposed architecture performs a SERDES function at the module side by exploiting a forwarded clock from the ASIC. Due to the relaxed channel loss of the ASIC-to-module interface, the use of power-hungry equalizers can be avoided. Based on an 850-nm multi-mode fiber interface, a 25-Gb/s link operation is demonstrated. A vertical-cavity surface-emitting laser-based transmitter outputs an optical modulation power of 0.6 mW. The optical receiver sensitivity is measured to be -7.5 dBm at 21.2 Gb/s with an optical excitation, and 120 μApp at 25 Gb/s with an electrical excitation. The jitter tracking capability of the implemented clock and data recovery is evaluated in the presence of ±100ppm frequency offsets and the measured jitter tolerance complies with the 100 GbE specification well. The optical transceiver is implemented in 65-nm CMOS technology and consumes 281 mW at 25 Gb/s, corresponding to the energy efficiency of 11.2 pJ/b.

Anisotropic conductive paste (ACP) or anisotropic conductive film (ACF) consisting of a polymer matrix and a metal-coated polymer bead are introduced as interconnection materials in mini-LED display panel packaging through a thermal compression bonding process. However, this packaging solution has been leading to important problems such as alignment difficulties due to high bonding temperature and pressure, and its repair issues for bad LED devices after the bonding process. Recently, laser-assisted bonding (LAB) process for mini-LED display packaging has been introduced to solve these problems[Ref. 1-2]. This study introduces, an anisotropic solder paste (ASP) using conductive solder particles and applies it to the mini-LED packaging through the LAB process.