Characterization of the die-attach process via low-temperature reduction of Cu formate in air

Choi, Woo Lim; Kim, Young Sung; Lee, Ki-Seong; Lee, Jong‐Hyun

doi:10.1007/s10854-019-01317-w

Cited by 11 publications

(3 citation statements)

References 32 publications

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“…Consequently, the results in Figure 4b indicate again that the addition method of Cu2O was very successful in enhancing the growth of the copper formate layer and the coverage of the copper formate shells. The copper formate layer eventually decomposed from approximately 220 °C, generating active Cu atoms using Equation (3) [36]. This decomposition beginning temperature was similar to the result of a previous similar measurement [37], and it appeared to be somewhat delayed compared to the result measured at a relatively low heating rate of 10 °C/min [36].…”

Section: Characteristics Of Cu Particles After Surface Treatmentsupporting

confidence: 80%

“…The copper formate layer eventually decomposed from approximately 220 • C, generating active Cu atoms using Equation (3) [36]. This decomposition beginning temperature was similar to the result of a previous similar measurement [37], and it appeared to be somewhat delayed compared to the result measured at a relatively low heating rate of 10 • C/min [36].…”

Section: Characteristics Of Cu Particles After Surface Treatmentsupporting

confidence: 80%

“…After treatment for 10 min (Figure 3b), the Cu particle surface maintained a smooth state at low magnification; however, nanoscale surface roughness was observed at high magnification in the form of a nanosized copper formate seed layer through Equation ( 1) [35]. Furthermore, following the subsequent reaction of Equation ( 2) with the addition of Cu2O, the thickness of the copper formate layer increased with an increase in the treatment time to 50 min (Figure 3c) [36]. The particle surface exhibited adequate coverage by the copper formate layer with an increased surface roughness.…”

Section: Characteristics Of Cu Particles After Surface Treatmentmentioning

confidence: 99%

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Controlling the Amount of Copper Formate Shells Surrounding Cu Flakes via Wet Method and Thermo-Compression Sinter Bonding between Cu Finishes in Air Using Flakes

Choi,

Lee

2023

Metals

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To bond a semiconductor power chip on a substrate using the formation of bondlines exhibiting long-term mechanical durability at high temperatures such as 300 °C, compression-assisted sinter bonding between Cu finishes was carried out at 300–350 °C in air. Cu flakes of approximately 7 µm were used as the main filler material; their surfaces were modified by pretreatment using a formic acid solution, and the existing oxide layers were transformed into copper formate shells. To increase the amount of the copper formate shells, the shell transformation reaction was controlled by the deliberate addition of 30 nm Cu2O particles and sustained for 50 min. The formate shells formed decomposed at a peak temperature of 250 °C, forming pure Cu, which rapidly induced sintering between the flakes and at the Cu-finish–flake interfaces. Therefore, the paste containing Cu flakes showed a sufficient shear strength of 26.3 MPa even in air after sinter bonding for only 3 min under 5 MPa at 350 °C. Although the bimodal-type paste presented near-full-density bondline structures within 3 min of adding 350 nm pure Cu particles, the strengths with respect to bonding time showed trends of values less than 26.3 MPa, owing to the excessive oxidation of the 350 nm Cu.

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Section: Characteristics Of Cu Particles After Surface Treatmentsupporting

confidence: 80%