Die-Attach Bonding with Etched Micro Brass Metal Pigment Flakes for High-Power Electronics Packaging

Abstract

Sinter pastes for rapid and low-temperature die-attach bonding are developed to enable sintering under a nitrogen atmosphere. First, microscale brass metal pigment flakes are stirred in hydrochloric acid to selectively etch zinc from the alloy composition, creating surface modifications. A binder mixture of α-terpineol and polyethylene glycol 600 (PEG600) is used to prepare the sinter paste. The surface modifications provide accelerated material transport, leading to improved sintering capabilities even at low sintering temperatures (≤275 °C). A bulk-like sintered microstructure with <10% porosity is achieved with a low solid content of 60 wt % in the paste formulation due to improved coarsening and densification behavior as a result of the surface modifications. PEG 600 is observed to be effective in reducing the copper oxides in situ during the sinter process. A shear strength of 30 MPa is achieved while sintering with 10 MPa bonding pressure at 275 °C for just 1 min, which is comparable to the performance of sintering under the same bonding conditions with commercially available silver pastes. The characterization of the flakes involved in the etching phenomenon and the influence of sintering parameters on the development of the microstructure are discussed in detail.

Micro-Raman for Local Strain Evaluation of GaN LEDs and Si Chips Assembled on Cu Substrates

“…Various methods have been employed over the years to determine the value of K, so today, both experimental and calculated values are available, and experimental data also confirm the linear approximation. For GaN crystals in wurtzite symmetry, the phonon shifts (∆ω) of the E H 2 Raman mode are represented by the following simplified equation, which allows the calculation of the induced strain of the experimental Raman shift [22]:…”

Understanding Cu Sintering and Its Role on Corrosion Behaviour for High-Temperature Microelectronic Application

“…The increasing need for high-temperature electronics (above 175 °C) has driven various advancements in the field of die-attach bonding, ranging from the development of new high-temperature solders to silver (Ag) nanoparticle sintering [1][2][3][4]. However, these solutions tend to be relatively expensive compared to the previous solder solution based on Pb5Sn.…”

“…However, these solutions tend to be relatively expensive compared to the previous solder solution based on Pb5Sn. As a result, the microelectronic industry is under significant pressure to reduce packaging costs, leading to a growing momentum in the exploration of more affordable alternatives such as copper (Cu) sintering [1,2].…”

“…The industry has recognised the potential of Cu sinter pastes as a costeffective solution to meet the requirements of hightemperature electronics while maintaining optimal performance. However, there are significant challenges to overcome [1,2]. One major challenge is the inherent tendency of Cu to undergo oxidation, which is a spontaneous reaction that becomes more favourable with increasing temperature.…”

Robust Cu–Cu Bonding with Multiscale Coralloid Nano-Cu3Sn Paste for High-Power Electronics Packaging

“…Therefore, it is urgent to develop an efficient, low-cost, and ecofriendly method to replace the existing production process. Recently, nanopastes prepared with antioxidant nanoparticles and ecofriendly reducing organic solvents could realize direct bonding of bare copper in air, which provides a possible solution to the above problems. − The added reducing organic solvents such as CELTOL-IA, ascorbic acid, glycerol, and polyethylene glycol (PEG) − can alleviate the rapid oxidation of the Cu substrate during the sintering process in air. Inspired by this idea, the antioxidation nano-Cu 3 Sn IMCs with organic solvent PEG-400 are first directly bonded with the bare Cu substrate in air to obtain a full-Cu 3 Sn joint.…”