Silicone die bond adhesive and clean in-line cure for copper lead frame

Suzuki, Kengo; Higashino, T.; Tsubosaki, Kunihiro; Kabashima, A.; Mine, Kenichiro; Nakayoshi, Kazumi

doi:10.1109/33.62534

Cited by 4 publications

(2 citation statements)

References 7 publications

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“…The interfacial adhesion strength between the silicone encapsulant and the side wall of the LED lead-frame cup using customized pin-push test was evaluated by Zhong et al [38] and the normal and shear stress distribution along the concerned interfaces was obtained. Furthermore, Suzuki et al [39] proved that the silicone material acts as diebond adhesive to reduce the thermal mismatch between the silicon die and the copper lead-frame. They also pointed out that ionic contaminants from the die bond adhesive deteriorates its moisture resistance.…”

Section: Introductionmentioning

confidence: 99%

Exploring water and ion transport process at silicone/copper interfaces using in-situ electrochemical and Kelvin probe approaches

Munirathinam

Dam

Herrmann

et al. 2021

Journal of Materials Science & Technology

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In general, packaging materials which encapsulate light emitting diodes (LEDs) and microelectronic devices offer barrier protection against several environmental hazards such as water and ionic contaminants. However, these encapsulants may provide pathways for water and ionic contaminants to reach the metal/polymer interfaces and provoke local corrosion of electronics, which is a major reliability concern for polymer encapsulated LEDs and microelectronics. As the water and corrosive constituents play a crucial role in their reliability, water uptake kinetics, interfacial ion transport and delamination behaviour of silicone coated copper model system, mimicking a typical microelectronics packaging system, is explored in the present work. Electrochemical impedance spectroscopy (EIS) integrated with attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy studies revealed that water diffusion inside the silicone network is Fickian in nature and the evolution of the observed time constants are related to the diffusion and interfacial reactions. A decrease of impedance magnitude with time was observed in EIS measurements concurrently with water absorption bands shifting towards lower wavenumber in ATR-FTIR measurements, implying the growth of strong hydrogen bonding between water molecules and the silicone network. The estimated diffusion constant of water using the capacitance method was in the order of 7 × 10 -12 m 2 s −1 and the water absorption volume fraction was in the range of 0% to 0.30%. Scanning Kelvin probe studies elucidated the ion transport process occurring at the silicone/copper interface in a humid atmosphere. The interfacial ion transport process is controlled by the interfacial electrochemical reactions at the cathodic delamination front and the estimated average delamination rate is 0.43 mm h -1/2 . This work demonstrates that exploring ion and water transport in the silicone coating and along the silicone/copper interface is of pivotal importance as part of a detailed reliability assessment of the polymer encapsulated LEDs and microelectronics.

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Section: Introductionmentioning

confidence: 99%

Exploring water and ion transport process at silicone/copper interfaces using in-situ electrochemical and Kelvin probe approaches

Munirathinam

Dam

Herrmann

et al. 2021

Journal of Materials Science & Technology

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“…In bonding large semiconductor chips, a major challenge is to manage the large mismatch in coefficient of thermal expansion (CTE) between silicon of 3 ppm/ C and copper of 17 ppm/ C [6]. For III-V compound semiconductors, the CTE ranges from Manuscript Traditionally, silicon devices are attached to copper lead-frames using silver-filled adhesives which can deform more easily to deal with the CTE mismatch [7]. Silver-filled adhesives have low thermal conductivity and low electrical conductivity.…”

Section: Introductionmentioning

confidence: 99%

Ag–Copper Structure for Bonding Large Semiconductor Chips

Kim

Wang

Lee

2008

IEEE Trans. Comp. Packag. Technol.

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Ag-copper dual-layer substrate design is presented. The Ag cladding on the copper substrate is a buffer to deal with the large mismatch in coefficient of thermal expansion (CTE) between semiconductors such as Si (3 ppm/ C) and Cu (17 ppm/ C). Ag is chosen because of its low yield strength, only one-tenth of that of Cu and one-third of the popular Sn3.5Ag solder. Other advantages are high electrical conductivity and high thermal conductivity. To bond Si chips to the Ag layer on copper substrates, Sn-rich solder is used. A fluxless bonding process is designed and developed. The bonding media are Ni/Sn/Au multilayer solder structure plated over Ag. In this design, Ni is a diffusion barrier between Sn and Ag. The thin (100 nm) outer Au layer prevents inner Sn from oxidation. The Si chip is deposited with Cr/Au under bump metallurgy (UBM). The bonding process is performed in 50-mtorr vacuum atmosphere without any flux. Comparing to bonding in air, the oxygen content is reduced by a factor of 15 200. The resulting joints consist of three distinct layers, i.e., Sn-rich layer, Ni 3 Sn 4 intermetallic compound, and Ni. Scanning acoustic microscopy (SAM) is used to verify the quality of the joint. Microstructure and composition of the joints are studied using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). This technique presents an initial success in overcoming the very large mismatch in thermal expansion between silicon and copper. It can be applied to mounting numerous high-power silicon devices to Cu substrate for various applications such as hybrid automotive and high-voltage power networks.

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Low moisture polymer adhesive for hermetic packages

Nguyen¹,

Grosse

1992

IEEE Trans. Comp., Hybrids, Manufact. Technol.

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Silicone die bond adhesive and clean in-line cure for copper lead frame

Cited by 4 publications

References 7 publications

Exploring water and ion transport process at silicone/copper interfaces using in-situ electrochemical and Kelvin probe approaches

Exploring water and ion transport process at silicone/copper interfaces using in-situ electrochemical and Kelvin probe approaches

Ag–Copper Structure for Bonding Large Semiconductor Chips

Low moisture polymer adhesive for hermetic packages

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