Hermetic Seal Device | ScienceGate

AbstractA wafer level packaging technique that involves anodic bonding of Pyrex wafers to released surface micromachined wafers is demonstrated. Besides providing a hermetic seal, this technique allows full wafer release, provides protection during die separation, and offers the possibility of integration with optoelectronic devices. Anodic bonding was performed under applied voltages up to 1000 V, and temperatures ranging from 280 to 400°C under vacuum (10-4Torr). The quality of the bonded interfaces was evaluated using shear strength testing and leak testing. The shear strength of Pyrex-to-polysilicon and aluminum bonds was ∼10-15 MPa. The functionality of surface micromachined polysilicon devices was tested before and after anodic bonding. 100% of thermal actuators, 94% of torsional ratcheting actuators, and 70% of microengines functioned after bonding. The 70% yield was calculated from a test sample of 25 devices.

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Comparison of hermetic sealing using SAC and SnPb solder for a MEMS pressure sensor

Additional Conferences (Device Packaging HiTEC HiTEN & CICMT) ◽

10.4071/2016dpc-ta32 ◽

2016 ◽

Vol 2016 (DPC) ◽

pp. 000464-000487

Author(s):

Maaike M. Visser Taklo ◽

Branson Belle ◽

Joachim Seland Graff ◽

Astrid-Sofie Vardøy ◽

Elisabeth Ramsdal

Keyword(s):

Cross Sections ◽

Pressure Sensors ◽

Thick Layer ◽

Long Term Effects ◽

Soldering Process ◽

Long Term Stability ◽

Hermetic Seal ◽

Reduced Rate ◽

Mems Pressure Sensors

In order to minimize the influence of packaging stress on the signal of MEMS pressure sensors, the pressure inlet can be reduced in footprint and mechanically decoupled from the mechanically moving parts. Moreover, the formation of a hermetic seal between the sensor inlet and an external inlet becomes more challenging as the footprint is reduced. Soldering is a preferred solution as a hermetic seal is achievable despite some surface roughness at the surfaces to be joined. However, the metallization on the MEMS, the solder and the metallization on the external inlet must be carefully matched to assure long term stability; the solder will react quickly with the metal layers deposited on the surfaces during the reflow process and later at a reduced rate during storage and application. The formation of intermetallic compounds (IMC) can catastrophically degrade the integrity of a joint if large amounts of voids are formed or the mechanical compliance significantly reduces as a result of the IMC formation. The metallization alternatives for the MEMS in this case were sputtered TiW/Au and NiCr/Au. The TiW and NiCr are adhesion layers whereas the Au is applied as a wetting layer which is normally fully consumed during the soldering process. A thick layer of plated Au, or a thick layer of plated Ni with a thin surface finish layer of Au, were possible metallization alternatives for the external inlet. Dewetting of solder from TiW is frequently mentioned in literature, but less conclusive work is published about soldering to NiCr/Au [1–3]. In particular, limited work has been published on long term effects of soldering to NiCr/Au surfaces using a SAC solder. In this work TiW and NiCr were compared as adhesion layers. In addition, SAC and SnPb were compared as solder, and Au and Ni/Au were compared as metallization on the external inlet. A total of 10–20 assemblies were prepared for each of 12 tested combinations. Half of the assemblies were exposed to high temperature storage (HTS) for ~300 hours at 130–150 °C. Shear testing and inspection of fracture surfaces and cross sections using light microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were performed for samples

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Optimization and sensitivity analysis of fast ethanol assay in maize seeds

Journal of Seed Science ◽

10.1590/2317-1545v41n1206316 ◽

2019 ◽

Vol 41 (1) ◽

pp. 97-107 ◽

Cited By ~ 1

Author(s):

Damrongvudhi Onwimol ◽

Thunyapuk Rongsangchaicharean ◽

Pitipong Thobunluepop ◽

Tanapon Chaisan ◽

Wanchai Chanprasert

Keyword(s):

Quality Assessment ◽

Ethanol Production ◽

Seed Quality ◽

Storage Conditions ◽

Ambient Conditions ◽

Maize Seed ◽

Seed Deterioration ◽

Maize Seeds ◽

Hermetic Seal

Abstract: The evaluation of seed deterioration is very important to control the quality of the seeds stored. This study aimed to investigate the potential of fast ethanol assay for seed quality assessment of maize stored under different conditions. The first experiment was to determine the incubating temperature, incubating time, and amount of seed used in the assay. The results showed that the best protocol for the detection of headspace ethanol was incubation of 3 g of maize seed with 20% moisture content (wet basis) in a 20 mL gas chromatography vial at 70 °C for 1.5 h. The assay induced approximately 200-700 µg.L-1 of headspace ethanol, which was sufficient to identify seeds with different vigour levels. In the second experiment, the optimal conditions were used for quality assessment in aged maize seed stored for 12 months under different storage conditions. The increase in the ethanol production of stored maize seed under the controlled conditions (15 °C and 20% RH in the hermetic seal) was lower than under ambient conditions. The ethanol production levels of maize seed samples at the start of storage was significantly lesser than at six months storage (p < 0.05). The test limitations in deteriorated seed with different cultivars and ages will be discussed.

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Metallization Behavior in Aluminum Nitride Electronic Packages

MRS Proceedings ◽

10.1557/proc-203-247 ◽

1990 ◽

Vol 203 ◽

Author(s):

Ellice Y. Luh ◽

Leonard E. Dolhert ◽

Jack H. Enloe ◽

John W. Lau

Keyword(s):

Thermal Conductivity ◽

Dielectric Properties ◽

Aluminum Nitride ◽

High Density ◽

High Thermal Conductivity ◽

Electronic Packages ◽

Oxide Ceramics ◽

Chemical Behavior ◽

Hermetic Seal ◽

Silicon Based

ABSTRACTCharacteristics such as CTE close to that of silicon, high thermal conductivity, and good dielectric properties make aluminum nitride (AIN) an excellent dielectric for packaging silicon-based high density multichip interconnects. However, there remains many aspects of its behavior that have not been characterized. One such example is the behavior of the various metallizations used within a package. As with A12O3, these metallizations must contribute toward a hermetic seal separating the die from the environment. However, the chemical behavior of the metallization systems used for A12O3 may not be compatible with non-oxide ceramics such as AIN. Consequently, these chemical interactions are investigated in view of the requirements for each application within electronic packages. Hermeticity testing results are also included in the discussion.

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Modification for scroll wrap height of a scroll compressor

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406211414640 ◽

2011 ◽

Vol 226 (3) ◽

pp. 763-774 ◽

Cited By ~ 1

Author(s):

Q Jianguo

Keyword(s):

Mass Production ◽

Axial Deformation ◽

Scroll Compressor ◽

Design Modification ◽

Shaft System ◽

Hermetic Seal ◽

Single Piece ◽

Simulation Results ◽

Special Modification

In order to obtain better axial hermetic seal of scroll compression chambers and hence a better performance for a scroll compressor, two modification methods for scroll wrap height are proposed based on the axial deformation of the scroll wrap. First, the design modification, which allows the scroll wrap height and its dimensional tolerances to be designed based on the axial deformation of scroll wrap in the basic shaft system, is suitable for mass production of scroll compressors. Second, the special modification, which allows the scroll wrap height to be modified based on the axial deformation of scroll wrap after its manufacturing, can be used for single-piece production of scroll compressor or for the scroll compressors available. A special modification was conducted for a scroll compressor, in which the orbiting scroll wrap was modified based on the simulation results of its axial deformation. According to the tests conducted later, the performance of the scroll compressor with modified scroll wrap can significantly be improved without deteriorating its original manufacturing precision.

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