High Temperature Lead‐Free Bonding Materials – The Need, the Potential Candidates and the Challenges

Zhang, Hongwen; Lee, Ning‐Cheng

doi:10.1002/9781119482093.ch6

Cited by 7 publications

(9 citation statements)

References 41 publications

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“…The selected combination is expected to deliver better thermal conductivity and less electrical resistivity than high-Pb since Sn is intrinsically superior to Pb in thermal and electrical performance. SnSb-based high-temperature alloys [1] have a solidus temperature at 326°C and a liquidus temperature around 366°C, shown in Figure 1. The 366°C liquidus temperature is 30-40°C higher compared to high-Pb solders, which need the higher reflow temperature during soldering.…”

Section: Design Of the Pastementioning

confidence: 99%

“…The 366°C liquidus temperature is 30-40°C higher compared to high-Pb solders, which need the higher reflow temperature during soldering. SnSb-based high-temperature alloys (dominated by SnSb IMC compounds) are strong and rigid, which may risk shattering large-sized Si die if reflowing under the high peak temperature profile [1][2][3][4]. Sn-rich solders are much more ductile and have a relatively low-melting temperature.…”

Section: Design Of the Pastementioning

confidence: 99%

“…Development of high-temperature Pb-free (HTLF) solder pastes to replace high-Pb (Pb>85wt%) solders for dieattachment in power device applications is driven by (1) the harmful effects of lead on human health and the environment (RoHS, WEEE, etc. ), and (2) the demand for improved performance for higher efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to a solder alternative, sintering, semi-sintering, and Ag-epoxy options have also been attempted for many years. However, each of the candidates satisfied only the niche application [1,2].…”

Section: Introductionmentioning

confidence: 99%

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A Drop-in High-Temperature Pb-Free Solder Paste that Outperforms High-Pb Pastes in Power Discrete Applications

Zhang,

Richmond,

Lytwynec

et al. 2023

IMAPSource Proceedings

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Sn-based high-temperature lead-free (HTLF) solder pastes have been developed as a drop-in solution to replace the high-Pb solder pastes in power discrete applications. The pastes were designed to combine the merits of two constituent powders. A SnSbCuAg powder, with the melting temperature above 320°C, was designed to maintain a high-temperature performance. A SnAgCuSb powder, with a melting temperature around 228°C, was added to the paste to enhance wetting and improve joint ductility. In the design, the final joint will have the low-melting phase (the melting temperature >228oC) in a controllable quantity embedded into the high-melting SnSbCuAg matrix. HTLF-1, one of the designs, maintained the bond shear strength up to 15MPa, even around 290°C. Another design, HTLF-2, has a similar bond shear strength as Pb92.5/Sn5/Ag2.5 around 290°C, but exceeds substantially below 250°C. The power discrete components had been built with both HTLF solder pastes for both die-attach and clip-bond through the traditional high-Pb process, which demonstrated the drop-in processing compatibility. The components survived three additional SMT reflows (peak temperature of 260°C) and passed moisture sensitivity level 1. This confirmed that the maintained joint strength (comparable to or stronger than high-lead), helped to keep the joint integrity within the encapsulated components, even with melting phases in a controllable quantity existing above 228°C. Both HTLF solder pastes outperformed Pb92.5/Sn5/Ag2.5 in RDS(on) even after 1000cycles of TCT (-55/175oC), which is attributed to the intrinsic lower electrical resistivity of Sn of both HTLF pastes. Microstructural observation had shown no corner cracks for both die-attach and clip-bond joints after TCT.

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Section: Design Of the Pastementioning

confidence: 99%

Section: Design Of the Pastementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Drop-in High-Temperature Pb-Free Solder Paste that Outperforms High-Pb Pastes in Power Discrete Applications

Zhang,

Richmond,

Lytwynec

et al. 2023

IMAPSource Proceedings

View full text Add to dashboard Cite

show abstract

“…The major requirements for HTLF solder pastes for power discrete applications (die-attach and clip-bond) include [2][3][4][5][6]: a remelting temperature higher than 260 C to maintain joint integrity while undergoing subsequent SMT reflows, a service temperature of 150 C or higher, a drop-in solution compatible with the current high-lead soldering and subsequent packaging processes, good thermal fatigue resistance, comparable or even superior electrical/thermal performance to high-lead solders, and relatively low cost. Efforts for seeking a drop-in solution with improved performance have been attempted for more than two decades.…”

Section: Introductionmentioning

confidence: 99%

A Drop-In High-Temperature Pb-Free Solder Paste That Outperforms High-Pb Pastes in Power Discrete Applications

Zhang,

Richmond,

Aserian

et al. 2023

Journal of Microelectronics and Electronic Packaging

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Sn-based high-temperature Pb-free (HTLF) solder pastes have been developed as a drop-in solution to replace high- Pb solder pastes in power discrete applications. The pastes were designed with Indium Corporation’s DurafuseVR technology, to combine the merits of two constituent powders. A SnSb-based Ag/ Cu-containing high-temperature powder, with a melting temperature above 320 degrees C, was designed to maintain high-temperature performance. A Sn-rich SnAgCu-Sb powder, with a melting temperature around 228 degrees C, was added to the paste to enhance wetting and improve joint ductility. In the design, the final joint will have the low-melting phase (the melting temperature >228 degrees C) in a controllable quantity embedded into the high-melting SnSb matrix. HTLF-1, one of the designs, maintained the bond shear strength up to 15 MPa, even around 290 degrees C. Another design, HTLF-2, has a similar bond shear strength as Pb92.5/Sn5/Ag2.5 around 290 degrees C, but exceeds substantially below 250 degrees C. The power discrete components had been built with both HTLF solder pastes for both die-attach and clip-bond through the traditional high-Pb process, which demonstrated the drop-in processing compatibility. The components survived three additional surface mounting (SMT) reflows (peak temperature upto 260 degrees C) and passed moisture sensitivity level 1 (MSL1). This confirmed that the maintained joint strength (comparable to or stronger than high-Pb), helped to keep the joint integrity within the encapsulated components in the following SMT process, even with the controlled quantity of the melting phases above 228 degrees C. Both HTLF solder pastes outperformed Pb92.5/Sn5/Ag2.5 in the resistance from drain to source when power is on (RDS(on)), even after 1,000 cycles of temperature cycling test (TCT) under 255/175 degrees C, which is attributed to the intrinsic lower electrical resistivity of Sn in both HTLF pastes. Microstructural observation had shown no corner cracks for both die-attach and clip-bond joints after TCT.

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Hybrid Cu sinter paste for low temperature bonding of bare semiconductors

Elger,

Krishna Bhogaraju,

Schneider-Ramelow

2024

Materials Letters

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High Temperature Lead‐Free Bonding Materials – The Need, the Potential Candidates and the Challenges

Cited by 7 publications

References 41 publications

A Drop-in High-Temperature Pb-Free Solder Paste that Outperforms High-Pb Pastes in Power Discrete Applications

A Drop-in High-Temperature Pb-Free Solder Paste that Outperforms High-Pb Pastes in Power Discrete Applications

A Drop-In High-Temperature Pb-Free Solder Paste That Outperforms High-Pb Pastes in Power Discrete Applications

Hybrid Cu sinter paste for low temperature bonding of bare semiconductors

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