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

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

Facile fabrication of highly sensitive and durable cotton fabric-based pressure sensors for motion and pulse monitoring

2021 ◽  
Author(s):  
Yinan Zhao ◽  
Lin Liu ◽  
zhen Li ◽  
Feifei Wang ◽  
Xinxin Chen ◽  
...  
Keyword(s):  
Cotton Fabric ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Wearable Electronics ◽  
Term Stability ◽  
Long Term Stability ◽  
Highly Sensitive ◽  
Facile Fabrication ◽  
Flexible Pressure Sensors

Design and development of flexible pressure sensors with high sensitivity, long-term stability and simple fabrication processes is a key procedure to fulfill the applications in wearable electronics, e-skin and medical...

scholarly journals Effect of local heating of rat testes after suppression of spermatogenesis by pretreatment with a GnRH agonist and an anti-androgen

Reproduction ◽  
2002 ◽  
pp. 133-140 ◽  
Author(s):  
BP Setchell ◽  
L Ploen ◽  
EM Ritzen
Keyword(s):  
Cross Sections ◽  
Gnrh Agonist ◽  
Local Heating ◽  
Epididymal Sperm ◽  
Long Term Effects ◽  
Sperm Counts ◽  
Pachytene Spermatocytes ◽  
Tubular Diameter ◽  
Testis Mass

The effects of local heating of rat testes, in which spermatogenesis had been suppressed with injections of a GnRH agonist and an anti-androgen, were examined. Although the detrimental effects of heating were not as marked as those found in the testes of non-injected rats, the testes in which spermatogenesis was suppressed also showed a significant reduction in mass, the number of spermatozoa, tubular diameter and the percentage of normal tubular cross-sections at day 35 after heating. The results indicate that heating has an effect on cells in the testis other than those shown to be most susceptible to heat, namely pachytene spermatocytes and early spermatids, which were absent or markedly reduced in number when spermatogenesis was suppressed. The long-term effects of heating on the above parameters, as reported in a previous study, were also confirmed. However, in testes in which spermatogenesis was suppressed at the time of heating, there appeared to be no or a reduced long-term impairment of spermatogenesis, as determined by testis mass, the percentage of qualitatively normal tubules and epididymal sperm counts.

Estimation of the long-term stability of piezoresistive LTCC pressure sensors by means of low-frequency noise measurements

2013 ◽  
Vol 199 ◽  
pp. 334-343 ◽  
Author(s):  
Marina Santo Zarnik ◽  
Vlasta Sedlakova ◽  
Darko Belavic ◽  
Josef Sikula ◽  
Jiri Majzner ◽  
...  
Keyword(s):  
Pressure Sensors ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Term Stability ◽  
Long Term Stability ◽  
Noise Measurements

Anodic Bond Quality and impact on Pressure Sensor Long-Term Stability

2001 ◽  
Vol 681 ◽  
Author(s):  
Henry Allen ◽  
Kamrul Ramzan ◽  
Jim Knutti ◽  
Carl Ross ◽  
Tim Milliman ◽  
...  
Keyword(s):  
Pressure Sensor ◽  
Pressure Sensors ◽  
Barometric Pressure ◽  
Absolute Pressure ◽  
Glass Wafer ◽  
Bond Quality ◽  
Long Term Stability ◽  
Pressure Changes ◽  
The Impact

ABSTRACTSilicon pressure sensors have historically been fabricating by bonding a glass wafer to a micro-machined silicon wafer. The sensor may be sealed as an absolute pressure sensor by using planar glass and can then be used for detection of barometric pressure changes.It has generally been assumed that as long as the glass and silicon are reasonable clean, then the silicon-glass seal is good and the part becomes a reliable, stable sensor. This paper addresses a low-level drift that was identified in such an absolute pressure sensor. A Zero drift in the range of 0.1% FS was detectable under humidity stresses. The stress always caused drift in the same direction, indicating an effective increased pressure in the sealed cavity.The impact of various cleaning processes in reducing drift are reported. The improved process assure reliable product for applications such as automotive and altimeter applications.

New Developments and Applications of Coal Mine Pressure and Force Monitoring Technology

2011 ◽  
Vol 402 ◽  
pp. 583-587
Author(s):  
Qing Biao Wang
Keyword(s):  
Coal Mine ◽  
Pressure Sensors ◽  
Mine Pressure ◽  
New Techniques ◽  
New Developments ◽  
Long Term Stability ◽  
Wide Range ◽  
Force Monitoring ◽  
Frequency Variations

Some new techniques used to improve the characteristics of vibrating-wire sensor and their applications in coal mine pressure and force monitoring are summarized. First, the new mathematical model and its applications are given. Second, the match of wire and diaphragm for the horizontal wire type sensor to reduce the hysteretic of the sensor is presented. Third, the weak excitation of the wire is stated which can effectively solve the problem of frequency variations. At last, the techniques of piston-conveying pressure and force conversion can be used to improve the accuracy and long-term stability, and to design the wide range、 high accuracy、high resolution and long-term stable pressure sensors and force sensors.

scholarly journals Review of Ni-Cu Based Front Side Metallization for c-Si Solar Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-20 ◽  
Author(s):  
Mehul C. Raval ◽  
Chetan S. Solanki
Keyword(s):  
Fill Factor ◽  
Front Side ◽  
Soldering Process ◽  
Long Term Stability ◽  
Working Principle ◽  
Reduced Costs ◽  
Near Future ◽  
Lower Series

Given the high percentage of metal cost in cell processing and concerns due to increasing Ag prices, alternative metallization schemes are being considered. Ni-Cu based front side metallization offers potential advantages of finer grid lines, lower series resistance, and reduced costs. A brief overview of various front side patterning techniques is presented. Subsequently, working principle of various plating techniques is discussed. For electroless plated Ni seed layer, fill factor values nearing 80% and efficiencies close to 17.5% have been demonstrated, while for Light Induced Plating deposited layers, an efficiency of 19.2% has been reported. Various methods for qualifying adhesion and long term stability of metal stack are discussed. Adhesion strengths in the range of 1–2.7 N/mm have been obtained for Ni-Cu contacts tabbed with conventional soldering process. Given the significance of metallization properties, different methods for characterization are outlined. The problem of background plating for Ni-Cu based metallization along with the various methods for characterization is summarized. An economic evaluation of front side metallization indicates process cost saving of more than 50% with Ni-Cu-Sn based layers. Recent successful commercialization and demonstration of Ni-Cu based metallization on industrial scale indicate a potential major role of Ni-Cu based contacts in near future.

Treatment of Vocal Fold Immobility by Glutaraldehyde—Cross-Linked Collagen Injection: Longc-Term Results

1995 ◽  
Vol 104 (6) ◽  
pp. 437-441 ◽  
Author(s):  
Marc Remacle ◽  
Jean-Marc Dujardin ◽  
Georges Lawson
Keyword(s):  
Vocal Fold ◽  
Speech Therapy ◽  
Systemic Reaction ◽  
Long Term Effects ◽  
Maximum Phonation Time ◽  
Long Term Stability ◽  
Vocal Fold Immobility ◽  
The Voice

Fifty-three cases of unilateral vocal fold immobility treated by glutaraldehyde—cross-linked (GAX) collagen over a 6-year period with a mean follow-up of 4.5 years were reviewed for assessment of the immediate and long-term effects on phonation. The mean amount injected was 1.47 mL. No long-term local or systemic reaction to the collagen was seen. The median preoperative maximum phonation time (MPT) was 7.5 seconds, the median immediate postoperative MPT 12 seconds, and the median long-term postoperative MPT 11 seconds. The median preoperative phonatory quotient (PQ) was 564 mL/s. The median immediate postoperative PQ was 320 mL/s, whereas the median long-term postoperative PQ was 385 mL/s. The quantitative improvement in the voice as measured by the PQ was thus 67% for the short range and 49% for the long range. The decline in the results over time was 20.3%. Vocal frequency analysis showed that the fundamental frequency and harmonics returned and were maintained in the long term for more than 80% of the patients with the help of speech therapy. This relative stability is explained by the findings of previous histological work. The fact that collagen, unlike Teflon, does not cause an inflammatory reaction and the partial maintenance of the improvement achieved, which is to be compared with the instability of the effects produced by resorbable substances, make it the “least objectionable” injectable for the treatment of unilateral glottic fold immobility. One must overcompensate 20% to 30%, given the results of the long-term stability studies.

Long-Term Stability of Metal Lines, Polysilicon Gauges, and Ohmic Contacts for Harsh-Environment Pressure Sensors

2006 ◽  
Vol 6 (6) ◽  
pp. 1596-1601 ◽  
Author(s):  
Alexandru Andrei ◽  
Christophe Malhaire ◽  
Sebastiano Brida ◽  
Daniel Barbier
Keyword(s):  
Ohmic Contacts ◽  
Pressure Sensors ◽  
Harsh Environment ◽  
Term Stability ◽  
Long Term Stability
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