Tensile mechanical properties of sintered porous silver films and their dependence on porosity

Wakamoto, Keisuke; Mochizuki, Yo; Otsuka, Takukazu; Nakahara, Ken; Namazu, Takahiro

doi:10.7567/1347-4065/ab0491

Cited by 16 publications

(11 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The dwell time was set to 3 min. After 3000 cycles passed, the reliability was found to increase with decreasing s-Ag p. The results indicated that lower p of s-Ag had a good influence on TST reliability, which had good agreement with our mechanical testing results of s-Ag [27].…”

Section: Introductionsupporting

confidence: 85%

“…One of the difficulties is the s-Ag material characteristic that inevitably includes micropores as a stress concentration area. As for the essential steps for understanding the degradation mechanism during TST, many researchers have investigated micropores' dependence on s-Ag tensile mechanical properties [20][21][22][23][24][25][26][27][28]. Particularly, authors focused on micropores' dependence on its tensile mechanical properties by applying changed process pressure from 5 to 60 MPa with nanosized silver paste (NP) as a function of the s-Ag porosity rate (p) at room temperature [24].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Degradation Mechanism of Pressure-Assisted Sintered Silver by Thermal Shock Test

et al. 2021

Self Cite

View full text Add to dashboard Cite

This paper investigates the degradation mechanism of pressure-sintered silver (s-Ag) film for silicon carbide (SiC) chip assembly with a 2-millimeter-thick copper substrate by means of thermal shock test (TST). Two different types of silver paste, nano-sized silver paste (NP) and nano-micron-sized paste (NMP), were used to sinter the silver film at 300 °C under a pressure of 60 MPa. The mean porosity (p) of the NP and MNP s-Ag films was 2.4% and 8%, respectively. The pore shape of the NP s-Ag was almost spherical, whereas the NMP s-Ag had an irregular shape resembling a peanut shell. After performing the TST at temperatures ranging from −40 to 150 °C, the scanning acoustic tomography (SAT) results suggested that delamination occurs from the edge of the assembly, and the delamination of the NMP s-Ag assembly was faster than that of the NM s-Ag assembly. The NMP s-Ag assembly showed a random delamination, indicating that the delamination speed varies from place to place. The difference in fracture mechanism is discussed based on cross-sectional scanning electron microscope (SEM) observation results after TST and plastic strain distribution results estimated by finite element analysis (FEA) considering pore configuration.

show abstract

Section: Introductionsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Degradation Mechanism of Pressure-Assisted Sintered Silver by Thermal Shock Test

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…The s-Ag of p was calculated based on cross sectional SEM images because the method could give enough information about microstructure of s-Ag without any troublesome [ 9 , 11 , 14 ]. Figure 3 shows representative cross-sectional SEM image of s-Ag along with the binary image after filtering.…”

Section: Resultsmentioning

confidence: 99%

“…However, by virtue of including many pores in s-Ag, it is very difficult to finely estimate the mechanical behaviors. To date, many researchers have tried to examine how porous affect the mechanical properties of s-Ag [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ] by means of indentation test [ 20 ] and bending test [ 21 , 22 , 23 ]. Although the tensile test is one of the most basic mechanical property evaluation tests, these alternative mechanical tests have been utilized for the evaluation due to its technical simplicities.…”

Section: Introductionmentioning

confidence: 99%

“…Although the tensile test is one of the most basic mechanical property evaluation tests, these alternative mechanical tests have been utilized for the evaluation due to its technical simplicities. We investigated its porosity-dependent tensile mechanical properties of s-Ag thin films (8–10μm thick) as a function of the size of the pores therein [ 11 ], and revealed that a porosity of around 5% was good as mechanical structural material. In addition, some researchers have tried to reveal the temperature dependency of the tensile mechanical properties of s-Ag [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Temperature Dependence on Tensile Mechanical Properties of Sintered Silver Film

et al. 2020

Self Cite

View full text Add to dashboard Cite

This paper investigates the influence of temperature on tensile mechanical properties of sintered silver (s-Ag) films with 8–10 μm in thickness for fundamental reliability design of semiconductor systems. The s-Ag film sintered under a pressure of 60 MPa possesses the porosity (p) around 5% determined from cross-sectional scanning electron microscope (SEM) images. The stress–strain (S-S) curves of s-Ag and pure silver (p-Ag) films are obtained using originally designed uniaxial tensile tester at temperatures from 25 °C to 150 °C. The S-S curves of p-Ag indicate ductile behavior irrespective of temperature, whereas those of s-Ag indicate brittle-ductile transition at 120 °C. Compared with p-Ag, s-Ag possesses low Young’s modulus (E) and high ultimate tensile strength (UTS) below 80 °C. The mechanism of brittle-ductile transition is discussed based on fracture surface observation results.

show abstract

Microstructural Response of Highly Porous Sintered Nano-silver Particle Die Attachments to Thermomechanical Cycling

Agyakwa,

Robertson,

Dai

et al. 2024

J. Electron. Mater.

View full text Add to dashboard Cite

This paper deals with the performance of sintered nano-silver bonds used as wide-bandgap power module die attachment technology. The paper specifically explores the fine-scale microstructures of highly porous sintered attachments under power cycling to provide a deeper understanding of the significance of porosity as a reliability-related microstructural parameter. Attachments prepared at 220°C using a pressure of 6 MPa for 1 s (parameters known to generate approximately 50% porosity from previous work) and subsequently subjected to 650,000 power cycles between 50°C and 200°C are assessed. A correlative workflow integrating x-ray computed tomography, focused ion beam (FIB) and electron backscatter diffraction (EBSD) data is applied to merge meso- and nanoscale microstructural features to illuminate the degradation mechanisms. The as-sintered Ag layer has a high volume of heterogeneously distributed pores, and consists of randomly oriented equiaxed grains whose sizes vary depending on the local density of the region sampled. Power cycling promotes grain growth and the loss of twin boundaries, and these changes are more pronounced within more dense regions of the Ag attachment. In contrast, the copper substrate appears to undergo some grain refinement, with deformation twins visible within finer-grained zones during power cycling. Cracks, which appear to start off within the Ag layer, propagate across the Ag-Cu boundary and transgranularly through fine-grained regions within the copper with little tortuosity. These observations are discussed within the context of reliability behaviour. Graphical Abstract

show abstract

Tensile mechanical properties of sintered porous silver films and their dependence on porosity

Cited by 16 publications

References 26 publications

Degradation Mechanism of Pressure-Assisted Sintered Silver by Thermal Shock Test

Degradation Mechanism of Pressure-Assisted Sintered Silver by Thermal Shock Test

Temperature Dependence on Tensile Mechanical Properties of Sintered Silver Film

Microstructural Response of Highly Porous Sintered Nano-silver Particle Die Attachments to Thermomechanical Cycling

Contact Info

Product

Resources

About