Microstructures of silver films plated on different substrates and annealed at different conditions

Lin, Weitao; Sha, Chu-Hsuan; Wang, Pin J.; Lee, Chin C.

doi:10.1109/ectc.2011.5898754

Cited by 11 publications

(6 citation statements)

References 4 publications

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“…This was not a surprise. We have observed that the microstructure of Ag produced by electroplating changes widely with plating conditions and geometries [10]. The Si chip with Ag columns was bonded to Cu substrate at 260°C under 800 psi (5.52 MPa) pressure for 5 min.…”

Section: Resultsmentioning

confidence: 99%

Demonstration of silver micro-joints for flip-chip interconnect

Sha

Lee

2012

Microelectronic Engineering

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Section: Resultsmentioning

confidence: 99%

Demonstration of silver micro-joints for flip-chip interconnect

Sha

Lee

2012

Microelectronic Engineering

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“…The plating current density is 13 mA/cm 2 . Before the solid-state bonding process, the Ag (50 μm)/Cu substrates are annealed at 400°C for 5 h to increase Ag grain size to reduce the yield strength for the Ag layer so that it can deform more easily [18], [19]. The assembly is to fix the position of samples on the heating graphite platform with a static pressure in a vacuum chamber [20].…”

Section: A Fabrication Steps Of Ag Layer With the Annealing Stepmentioning

confidence: 99%

“…Hence, the yield strength depends on grain size while the grains are not extremely coarse or ultrafine [22], [23]. For the first design, to reduce the yield strength by increasing the grain size, the 50-μm Ag layers electroplated on Cu substrates were annealed at 400°C for 5 h [18]. As shown in Fig.…”

Section: A Bonding Design Of Ag Layer With the Annealing Stepmentioning

confidence: 99%

Novel Silver Solid-State Bonding Designs Between Two Copper Structures

Lee

2017

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

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“…The lacquer that protects other areas from Ag plating is then removed by soaking in acetone bath at room temperature. The assembly is thoroughly cleaned again and annealed at 350°C for 5 h to grow the Ag grains from 25 nm to a few microns, thus making it more ductile [24].…”

Section: Experimental Designs and Proceduresmentioning

confidence: 99%

A solid-state bonding technique of large copper wires for high power devices operating at high temperature

Lee

2015

J Mater Sci: Mater Electron

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Solid-state processes of bonding 1 mm copper (Cu) wires on Cu substrates and silicon (Si) chips, respectively, were developed. To overcome Cu oxidation issue, the bonding surface on the wire was plated a silver (Ag) layer. An annealing step followed to make the Ag layer much easier to deform and conform to the Cu or Si bonding surfaces. The bonding process was performed at 300°C with 6.89 MPa. Wire-bond cross sections were studied using optical and electron microscopy, respectively. The images obtained exhibit nearly perfect Ag-Cu bonding interface. For wire-bonds made on Cu substrate, in-plane (shear) pull test measured a breaking of force 20.7-23.7 kg, comparable to the 22.5 kg breaking force of the Cu wire itself. Breaking forces on vertical (peel) pull test are about one-half of in-plane pull test results. For wire-bonds made on Si chip, breaking forces are about 80 % of those made on Cu substrate. Fracture modes were evaluated in details. 90 % of the wire-bonds broke with three modes mixed together: near Cu-Ag plating interface, inside Ag layer, and Ag-Cu bonding interface. Thus, the bonding interface is as strong as other regions of the wirebond. This solid-state wire bonding process is expected to have valuable applications in high power and high temperature devices and modules where the wire-bonds have to stand alone without protection due to lack of high temperature molding compound and reinforcing materials.

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Microstructures of silver films plated on different substrates and annealed at different conditions

Cited by 11 publications

References 4 publications

Demonstration of silver micro-joints for flip-chip interconnect

Demonstration of silver micro-joints for flip-chip interconnect

Novel Silver Solid-State Bonding Designs Between Two Copper Structures

A solid-state bonding technique of large copper wires for high power devices operating at high temperature

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