Reliability Assessment of Ag Sintered Joints Using a SiC Semiconductor and Determination of Failure Mechanism in the Field of Power Electronics

Schaal, Marco; Klingler, Markus; Metais, B.; Gruninger, Ralph; Hoffmann, Stefan; Wunderle, Bernhard

doi:10.1109/eurosime48426.2020.9152674

Cited by 7 publications

(5 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Assembly samples were subjected to TST with the temperature fluctuating from −40 to 150 • C in each cycle. Each cycle lasted 30 min in accordance with general TST patterns as stated in the Introduction [19]. The bonded area was roughly evaluated by SAT every 100 cycles.…”

Section: Microporous Structure Of S-agmentioning

confidence: 99%

“…Generally, it is known that the die corner part where the thermo-mechanical stress concentrates becomes the initial die failure point, except in the case of the existence of another stress singularity point in the die layer [20,28]. In this study, the target bonded area ratio was set to 80% after 1000 cycles of TST passed, which is a conventional standard target as introduced before [19,20]. The results of the NP s-Ag and NMP s-Ag assemblies differ significantly.…”

Section: Microporous Structure Of S-agmentioning

confidence: 99%

“…In the TST, power modules are set in a heat chamber. The chamber temperature has commonly been set from −40 to 150 • C or −40 to 125 • C for a duration of 30 min to 2 h in the field of the automobile industry [19,20]. Figure 1 shows the TST design issue overview.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, degradation in the die layer causes shrinkage of the thermal pass area, which causes the total thermal impedance to be worse after the TST. The bonded area ratio has generally been set to above 80% after the TST [19,20]. Hence, degradation control during the TST plays a critical role for thermal designing in packages.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

et al. 2021

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: Microporous Structure Of S-agmentioning

confidence: 99%

Section: Microporous Structure Of S-agmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

et al. 2021

View full text Add to dashboard Cite

show abstract

“…In a TST, power modules are set in a chamber where the ambient temperature commonly varies from −40 to 150 °C. 11,12) Consequently, a bonded area deteriorates due to thermal stress originating from the different coefficient of thermal expansion (CTE) within each material composing the power modules. In the case of an s-Ag bonded layer, the fracture is commonly known to start at the top corner of the die area, where a crack initially propagates inside at an inclined angle, and then its propagation direction changes to the horizontal direction along the substrate surface.…”

Section: Introductionmentioning

confidence: 99%

Comparison of sintered silver die attach failure between thermal shock test and mechanical cycling test

Wakamoto

Kumakiri

Otsuka

et al. 2022

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

This paper compares the degradation of sintered silver (s-Ag) die attach between thermal shocked test (TST) and mechanical cycling test to correctly understand the mechanism of s-Ag die attach failure in power module products during practical operation. A bar-shaped specimen is subjected to two types of four-point bending tests: centered bending test (CBT) for bending moment application and shifted bending test (SBT) for shear force application. A crack path in SBT is like that in TST, which suggests that shear force has an important role for imitating the degradation and failure of s-Ag in TST. A crack propagation speed per cycle in TST is, however, about 4,000 times faster than that in SBT. The lifetime assessment period of SBT is approximately 1,400 times shorter than that of TST. The difference in failure mechanism between TST and SBT is discussed by scanning electron microscopy (SEM) of fractured specimens.

show abstract

Nine Point Bending Test Technique for Understanding of Sintered Silver Die Bonding Failure Mechanism

et al. 2023

View full text Add to dashboard Cite

The Sintered silver (s–Ag) die degradation is commonly evaluated by thermal shocked test (TST), which evaluates the material’s durability against a heating/cooling cycle. Materials with different coefficient of thermal expansion (CTE) give rise to thermal out-of-plane deformation surrounding the bonding part, which deteriorates s–Ag die part by repeated thermal and mechanical stress during TST. For the safe and reliable design of s–Ag die toward long-term durability, the contribution of thermal and mechanical stresses to degradation should be understood separately. Clarify the overall s–Ag die degradation mechanism during TST compared to the new mechanical bending test that can apply out-of-plane deformation. The authors propose a new mechanical bending test technique, called the nine-point bending (NBT) test, which can provide out-of-plane deformation with a s–Ag die-attached specimen as TST like. By comparing NBT and TST, the degradation mechanism of the s–Ag die-attach element can be understood from both thermal and mechanical aspects. In scanning acoustic tomography (SAT) analysis, a similar degradation ratio between NBT and TST is obtained, which indicates that mechanical stress plays a significant role in deteriorating s–Ag die layer in TST. After 1000 cycles, however, cracking and s–Ag material aging coexist in TST only, destabilizing s–Ag die fracture. s–Ag main degradation cause in TST is clarified with mechanical stress by comparing NBT. In addition, thermally material aging destabilized the s–Ag degradation during TST.

show abstract

Reliability Assessment of Ag Sintered Joints Using a SiC Semiconductor and Determination of Failure Mechanism in the Field of Power Electronics

Cited by 7 publications

References 24 publications

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

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

Comparison of sintered silver die attach failure between thermal shock test and mechanical cycling test

Nine Point Bending Test Technique for Understanding of Sintered Silver Die Bonding Failure Mechanism

Contact Info

Product

Resources

About