National Center for Advanced Packaging (China)

The rapid growth of plant-based biodegradable tableware, driven by plastic restrictions, necessitates rigorous safety assessments of potential chemical contaminants like per- and polyfluoroalkyl substances (PFASs). This study comprehensively evaluated PFAS contamination risks in commercial sugarcane pulp tableware, focusing on the residues of five target PFASs (PFOA, PFOS, PFNA, PFHxA, PFPeA) and their migration behavior under simulated use and takeout conditions. An analysis of 22 samples revealed elevated levels of total fluorine (TF: 33.7-163.6 mg/kg) exceeding the EU limit (50 mg/kg) in 31% of products. While sporadic PFOA residues surpassed the EU single compound limit (0.025 mg/kg) in 9% of samples (16.1-25.5 μg/kg), the levels of extractable organic fluorine (EOF: 4.9-17.4 mg/kg) and the low EOF/TF ratio (3.19-10.4%) indicated inorganic fluorides as the primary TF source. Critically, the migration of all target PFASs into food simulants (water, 4% acetic acid, 50% ethanol, 95% ethanol) under standardized use conditions was minimal (PFOA: 0.52-0.70 μg/kg; PFPeA: 0.54-0.63 μg/kg; others < LOQ). Even under aggressive simulated takeout scenarios (50 °C oscillation for 12 h + 12 h storage at 25 °C), PFOA migration reached only 0.99 ± 0.01 μg/kg in 95% ethanol. All migrated levels were substantially (>15-fold) below typical safety thresholds (e.g., 0.01 mg/kg). These findings demonstrate that, despite concerning residue levels in some products pointing to manufacturing contamination sources, migration during typical and even extended use scenarios poses negligible immediate consumer risk. This study underscores the need for stricter quality control targeting PFOA and inorganic fluoride inputs in sugarcane pulp tableware production.

The three-dimensional chiplet technology based on through-silicon via (TSV) active interposer is an effective way to continue increasing integration reducing power and improving performance as Moore’s law slows down. The TSV active interposer not only provides paths for die-to-die interconnections but also integrates logic functions. In this study, an active interposer fabrication technique for integrated TSVs was developed. The active interposer was successfully fabricated by the frontside via-last technology. However, due to the low-k material on the top side of the wafer, the process of the active interposer faces many challenges, including the TSV etching, the TSV cleaning, and the scribing of the low-k wafer. This work proposed the double-step protection method to avoid the overetching of TSV due to the porous structure of the low-k material. Then, the 350 °C baking for 1 h after the wafer cleaning method was proposed to avoid short-circuiting due to the water absorption characteristics of the low-k material. Besides, the blade saw followed by laser grooving method was proposed to avoid chipping and splattering of the wafer due to the low mechanical strength of the low-k material. Finally, the TSV active interposer was fabricated to conform with the design requirements and to satisfy the application of the 3-D chiplet. The dimension of the active interposer was <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$22\times 20$ </tex-math></inline-formula> mm. The main connection structures of the active interposer were fabricated by the back end of line (BEOL). The frontside contained the TSVs (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10\times 100~\mu $ </tex-math></inline-formula>m), three metal layers, and microbumps with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$26.2~\mu $ </tex-math></inline-formula>m diameter and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$18.8~\mu $ </tex-math></inline-formula>m height. The backside contained one metal layer and C4 bumps with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$77.6~\mu $ </tex-math></inline-formula>m diameter and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$77.3~\mu $ </tex-math></inline-formula>m height. The survival rate of the sample is about 89% after the 200 cycles thermal cycling test (TCT), from −40 °C to 125 °C.

for 5 μm diameter micro bumps, the interfacial intermetallic compounds (IMCs) seriously affects the interconnection performance of micro bumps. In this paper, we focused on the discussion of the growth and control mechanism of IMCs of 5um diameter micro bumps at different temperatures and durations. The growth mechanism and morphology of Ni3Sn4 IMC was studied. Through the EDS analysis of the cross-sectional micro bumps, it could be determined that the composition of the slender columnar crystal IMC was Ni3Sn4. When the heating temperature was higher than the melting point of Sn-3.0wt%Ag solder, the IMC would exhibit uneven and abnormal growth along the Sn grain boundary. Furthermore, the IMC growth and diffusion mechanisms of solid-solid and solid-liquid interface reaction were discussed respectively. Finally, based on the temperature and duration of the growth and evolution of the Ni3Sn4 IMC, we gave appropriate suggestions for the use of small-sized micro bumps.

Abstract This editorial introduces some recent editorial changes to the journal, including the appointment of a new Editor. It outlines the new editorial team's vision for PTS before noting some recent and forthcoming highlights.

A double-layer silicon-based stripline filter with a center frequency of 20.76 GHz and a bandwidth of 2 GHz was designed by using an aggressive space mapping (ASM) and fabricated with Microelectromechanical Systems (MEMS) technology. The measurements agreed well with simulation, showing efficiency and accuracy of the ASM algorithm. Over temperature range of −50 to 80°C, the filter's performance such as insertion loss, bandwidth and central frequency were investigated and discussed, and the measured frequency drift is −55.5 ppm/°C and the bandwidth variation is ±4% over temperature range of −50 to 80°C. At 150°C after 1000 h of aging test, although the insertion loss of the filter slightly increased from 2.18 to 2.4 dB and the passband ripple deteriorated, the stopband rejection performance improved.