Evolution of shear strength and microstructure of die bonding technologies for high temperature applications during thermal aging

Egelkraut, Sven; Frey, L.; Knoerr, Matthias; Schletz, Andreas

doi:10.1109/eptc.2010.5702721

Cited by 25 publications

(17 citation statements)

References 9 publications

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“…The present minimum average shear strength of 26.1 MPa obtained from Trial t1 is comparable with those of the Pb5Sn solder joints (18 to 25 MPa) and Au12Ge joints (25MPa) [7,[13][14][15]. The present average shear strengths in the range of 26.1MPa to 46.6MPa are also comparable with those of the sintered silver joints using wet silver pastes which took longer processing time [16,17].…”

Section: B Comparison With Existing Resultssupporting

confidence: 78%

Time-Efficient Sintering Processes to Attach Power Devices Using Nanosilver Dry Film

Dai¹,

Li²,

Agyakwa³

et al. 2017

Journal of Microelectronics and Electronic Packaging

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(2017) Time-efficient sintering processes to attach power devices using nanosilver dry film. Journal of Microelectronics and Electronic Packaging, 14 (4 A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk Abstract: Pressure-assisted sintering processes to attach power devices using wet nanosilver pastes with time scales of minutes to a few hours have been widely reported. This paper presents our work on time-efficient sintering, using nanosilver dry film and an automatic die pick and place machine, resulting in process times of just a few seconds. The combined parameters of sintering temperature 250 C, sintering pressure 10 MPa and sintering time 5 s were selected as the benchmark process to attach 2 mm × 2 mm × 0.5 mm dummy Si devices. Then the effects of either the sintering temperature (240 to 300 C), time (1 to 9 s) or pressure (6 to 25 MPa) on the porosity and shear strength of the sintered joints were investigated with 3 groups and a total of 13 experimental trials. The average porosities of 24.6 to 46.2% and shear strengths of 26.1 to 46.6 MPa are comparable with and/or even better than those reported for sintered joints using wet nanosilver pastes. Their dependences on the sintering temperature, time and pressure are further fitted to equations similar to those describing the kinetics of sintering processes of powder compacts. The equations obtained can be used to not only reveal different mechanisms dominating the densification and bonding strength, but also anticipate the thermal-induced evolutions of microstructures of these rapidly sintered joints during future reliability tests and/or in service.

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Section: B Comparison With Existing Resultssupporting

confidence: 78%

Time-Efficient Sintering Processes to Attach Power Devices Using Nanosilver Dry Film

Dai¹,

Li²,

Agyakwa³

et al. 2017

Journal of Microelectronics and Electronic Packaging

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show abstract

“…3, the sintered Ag joints either did not exhibit any reduction in die shear strength 32 or experienced an increase in die shear strength for longer aging times. 51,52 The reason for these results could be that with certain combinations of thickness, grain size, and purity in the metallization schemes, such as ''Ni/ Ag'' 51 or ''Ni/Au'', 52 it is possible to resist the failure related to the oxidation of the nickel barrier layer. The delamination and cracking of sintered Ag joints can be reduced by optimizing the sintering profile 55 or increasing the thickness of the die-attach layer 53,54 to allow the organics to dissipate at a lower sintering temperature.…”

Section: High-temperature Storage Testsmentioning

confidence: 99%

“…51 As a consequence of these competing mechanisms, the die shear strength of a thermally aged sintered Ag joint may not be straightforward to model or predict. We expect the die shear strength to reduce over time because processes (b) to (e) should occur to a greater extent with a longer aging duration and/or a higher annealing temperature.…”

Section: High-temperature Storage Testsmentioning

confidence: 99%

“…Such high-temperature studies are different from the sintering-time studies conducted during process development, which clearly demonstrate an increase in die shear strength for longer sintering times because of Ag densification. 5 Besides the continuous densification of Ag joints, other processes are also taking place during such hightemperature annealing studies [51][52][53] :…”

Section: High-temperature Storage Testsmentioning

confidence: 99%

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Are Sintered Silver Joints Ready for Use as Interconnect Material in Microelectronic Packaging?

Siow

2014

Journal of Elec Materi

270

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Silver (Ag) has been under development for use as interconnect material for power electronics packaging since the late 1980s. Despite its long development history, high thermal and electrical conductivities, and lead-free composition, sintered Ag technology has limited market penetration. This review sets out to explore what is required to make this technology more viable. This review also covers the origin of sintered Ag, the different types and application methods of sintered Ag pastes and laminates, and the long-term reliability of sintered Ag joints. Sintered Ag pastes are classified according to whether pressure is required for sintering and further classified according to their filler sizes. This review discusses the main methods of applying Ag pastes/laminates as dieattach materials and the related processing conditions. The long-term reliability of sintered Ag joints depends on the density of the sintered joint, selection of metallization or plating schemes, types of substrates, substrate roughness, formulation of Ag pastes/laminates, joint configurations (i.e., joint thicknesses and die sizes), and testing conditions. This paper identifies four challenges that must be overcome for the proliferation of sintered Ag technology: changes in materials formulation, the successful navigation of the complex patent landscape, the availability of production and inspection equipment, and the health concerns of Ag nanoparticles. This paper is expected to be useful to materials suppliers and semiconductor companies that are considering this technology for their future packages.

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“…A guideline for the maximum operation temperature of solder joints is at the homologous temperature of 0.8 [18]. At this temperature, even the aforementioned Ni coating method is not good enough.…”

mentioning

confidence: 99%

Fluxless Tin Bonding Process With Suppressed Intermetallic Growth

Hsu

Lee

2014

IEEE Trans. Compon., Packag. Manufact. Technol.

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Abstract-Soldering is a process that joins two metal parts with a low-melting-point metal or alloy, called solder. It is widely recognized that intermetallic compound (IMC) formation is essential for the solder to bond to metals. The IMC layer grows during soldering. It grows further during usage, in particular, at temperature near the solder melting temperature. Extensive IMC growth can result in reliability issues. A reason is that IMC is much less ductile than the solder and does not deform as much as the solder to manage the coefficient of thermal expansion mismatch between the parts joined. In this paper, we looked into and developed a soldering process to fabricate IMC-less solder joints. The fundamental concept is to choose a barrier metal that can bond to solder without forming IMC with the solder. With our experience and Cr-Sn phase diagram, Cr is selected as the barrier metal. Several bonding experiments have been performed and the preliminary results show that high quality Sn joints could be produced with a little IMC formation before high-temperature aging. After aging at homologous temperature of 0.9 of Sn for 100-200 h, Cu 6 Sn 5 and Cu 3 Sn IMCs are observed. They are caused by the penetration of molten Sn through microcracks or pinholes on the Cr layer to react with the underlying Cu. In production environment, the density of microcracks and pinholes can be greatly reduced to inhibit IMC growth, making the realization of solder joints without IMC a possibility.

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Evolution of shear strength and microstructure of die bonding technologies for high temperature applications during thermal aging

Cited by 25 publications

References 9 publications

Time-Efficient Sintering Processes to Attach Power Devices Using Nanosilver Dry Film

Time-Efficient Sintering Processes to Attach Power Devices Using Nanosilver Dry Film

Are Sintered Silver Joints Ready for Use as Interconnect Material in Microelectronic Packaging?

Fluxless Tin Bonding Process With Suppressed Intermetallic Growth

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