Assessment of Fluxless Solid Liquid Interdiffusion Bonding by Compressive Force of Au-PbSn and Au-SAC for Flip Chip Packaging

Lee, T.K.; Zhang, Sam; Wong, Chee Cheong; Tan, A.C.

doi:10.1109/tadvp.2008.2006650

Cited by 11 publications

(4 citation statements)

References 18 publications

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“…SLICF bonding was first optimized using Au stud to establish the bonding profiles. Au stud was able to form the interconnects with SAC without any flux [7][8]. A short bonding time of 3s was selected in consideration of manufacturability and productivity.…”

Section: Bonding Processmentioning

confidence: 99%

See 1 more Smart Citation

Comparison of SLICF with C4 for flip chip bonding with Au, Cu, Pd and Ag studs with SAC solder

Kheng

Leng

Ling

et al. 2013

2013 IEEE 15th Electronics Packaging Technology Conference (EPTC 2013)

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Flip Chip (FC) interconnects for 3D, 2.5D and wafer level packaging (WLP) are fast becoming a common package for high performance applications. One of key challenges identify in assembly lie in the fine pitch of FC interconnect to the substrate. This paper looks into an instantaneous fluxless bonding techniques of solid liquid interdiffusion by compressive force (SLICF) to form FC joints of Au, Cu, Pd coated Cu (Pd-Cu) and Ag with lead free SnAgCu (SAC) solder. The bumped chip with SAC solder bumps is then FC bonded onto the Au, Cu, Pd-Cu and Ag studs with macroscopic and microscopic analysis using Optical and Scanning Electron Microscope (SEM) respectively. Electron Dispersive X-ray (EDX) is performed to identify the intermetallics with its joint integrity assessed. Poor interconnect observed for Cu and Pd-Cu studs with plasma cleaning. Both Au and Ag demonstrated to be a good candidate to enable WLP interconnect for production for fine pitch FC applications. Ag provides a good alternative to Au for low cost flip chip technology as Ag provides a lower intermetallic growth rate than Au. Further process optimization is needed to enhance the reliability.

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Section: Bonding Processmentioning

confidence: 99%

“…Once inserted, the submerged body interacts with fresh solder to form bonds via solid-liquid interdiffusion. The bonds are mechanically interlocked upon cooling [6][7][8]. Figure 1 illustrates the working principle of SLICF bonding.…”

Section: Introductionmentioning

confidence: 99%

Comparison of SLICF with C4 for flip chip bonding with Au, Cu, Pd and Ag studs with SAC solder

Kheng

Leng

Ling

et al. 2013

2013 IEEE 15th Electronics Packaging Technology Conference (EPTC 2013)

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show abstract

“…At present, nearly all flip-chip joints in production are made of Tin (Sn)-based leaded or lead (Pb)-free solders [3][4][5][6][7][8]. The solder joints go through a molten state during the soldering process.…”

Section: Introductionmentioning

confidence: 99%

40 μm Ag/Au Flip-Chip Joints by Solid-State Bonding at 200°C

Lin¹,

Sha²,

Lee³

2013

Journal of Microelectronics and Electronic Packaging

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AbstractÀIn this research, 40 mm silver/gold (Ag/Au) composite flip-chip interconnect joints between silicon (Si) chips and copper (Cu) substrates were demonstrated. The bonding was achieved by a solid-state process at a low temperature of 2008C for 5 min with the pressure applied at 250À400 psi (1.7À2.7 MPa), corresponding to 0.22À0.35 g of force per joint. To begin with, an array of 50 3 50 30 mm Ag/10 mm Au columns with 40 mm in diameter and 100 mm in pitch was fabricated by photolithographic and electroplating processes on silicon (Si) chips which were first coated with chromium (Cr) and Au films. The columns on the chip were then bonded to a Cu substrate by solid-state bonding. Cross-sectional scanning electron microscopy (SEM) images show that the exposed Ag/Au columns were well bonded to the Cu substrate. No joint breakage was observed despite the large coefficient of thermal expansion (CTE) mismatch between Si and Cu. A pull test was conducted. The breaking force and fracture strength are 6.5À7.3 kg and 2,940À3,310 psi (20.2À22.8 MPa), respectively. The breaking force is 2.53 of the criterion specified in MIL-STD-883E. Fracture modes were examined. Three modes were classified by fracture interfaces as Si-glue, Si/Cr/Au/Ag, and Au-Cu bonding interface. Of all joints evaluated, 27% of them break on the Au-Cu substrate bonding interface. Accordingly, the bonding interface is least likely to break among interfaces of the joint structure.

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“…For flip chip package, bump process is indispensable. The material of bump is lead free solder [4][5] at present. Recently, the wafer-level chip-scale packaging [6][7][8][9] is widely applied in highperformance ICs.…”

Section: Introductionmentioning

confidence: 99%

A study to stencil printing technology for solder bump assembly

Wang

Hsieh

Huang

et al. 2009

2009 4th International Microsystems, Packaging, Assembly and Circuits Technology Conference

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In general, the stencil printing manufacturing in pre-WLCSP (wafer-level chip-scale packaging) is able to be integrated by 7-step processes, including two masks and one set of stencil plate. After the formation of solder ball, the specified professional probe card is needed to verify whether the electric functions of this packaged IC are good. After this step, the wafer grinding, the wafer cutting, the chip choice and the final test (F/T) are gradually adopted to proceed. Finally, due to the customer's need, the shipping package type to customers is, generally, tray or tape and reel. Although the stencil printing technology can provide the mass-production capability, the mainly existing problems of this technology are the quality of manufacturing steel plate, the coating operation for solder paste, and the flatness of wafer surface. These issues usually constrain the minimization of the size of the solder ball and the pitch. Thinking to solve these issues, this package technology is still feasible in assembly competition.

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Assessment of Fluxless Solid Liquid Interdiffusion Bonding by Compressive Force of Au-PbSn and Au-SAC for Flip Chip Packaging

Cited by 11 publications

References 18 publications

Comparison of SLICF with C4 for flip chip bonding with Au, Cu, Pd and Ag studs with SAC solder

Comparison of SLICF with C4 for flip chip bonding with Au, Cu, Pd and Ag studs with SAC solder

40 μm Ag/Au Flip-Chip Joints by Solid-State Bonding at 200°C

A study to stencil printing technology for solder bump assembly

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