Implementing Fringing Field Sensors in PCB Technology

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 000579-000598
Author(s):  
Robert Dean ◽  
Aditi Rane ◽  
Colin Stevens ◽  
Michael Baginski ◽  
Zane Hartzog ◽  
...  
Keyword(s):  
Moisture Content ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Interdigitated Electrode ◽  
Water Detection ◽  
Out Of Plane ◽  
Fringing Field ◽  
Mems Technology ◽  
Moisture Content Measurement ◽  
Fringing Fields

Interdigitated electrode structures are well suited for realizing capacitors where a significant percentage of the total capacitance in due to the out of plane fringing fields. An object that interferes with the fringing fields will then change the measurable capacitance between the electrodes. Therefore this configuration can be used as a sensor for the object that interferes with the fringing fields and is called a capacitive fringing field sensor. These types of sensors have been used in many applications, such as water detection, moisture content measurement and as proximity switches. Printed circuit board (PCB) technology is particularly useful for realizing this type of sensor architecture. The interdigitated electrode structures can be patterned in the Cu cladding on one or both sides of the substrate. The solder mask coating can then be used to insulate the electrodes to prevent shorting in the presence of water or other conductive substances. The size and spacing of the electrode structures can be optimized to adjust the sensitivity of the sensor to the measurand of interest. The implementation of this type of sensor in PCB technology has several advantages when compared to traditional MEMS technologies. External electronics can readily be attached to the PCB substrate. Very large sensor panels can be manufactured easily and economically. Other types of MEMS sensors have been implemented in PCB technology in recent years. This sensor is compatible with those types of sensors and could be used to augment sensor suites implemented in PCB MEMS technology. Demonstration prototype fringing field sensors were implemented in PCB technology for measuring the mass of small quantities of water, for measuring soil moisture content and for use as capacitive touch switches.

Experimental Investigation by Speckle Interferometry of Solder Joint Failure Under Thermomechanical Load Aggravated by Boundary Conditions at Board Level

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
D. N. Borza ◽  
I. T. Nistea
Keyword(s):  
Solder Joint ◽  
Fundamental Frequency ◽  
Printed Circuit Board ◽  
Speckle Interferometry ◽  
Circuit Board ◽  
Joint Failure ◽  
Printed Circuit ◽  
Out Of Plane ◽  
Fringe Patterns ◽  
Board Level

Reliability of electronic assemblies at board level and solder joint integrity depend upon the stress applied to the assembly. The stress is often of thermomechanical or of vibrational nature. In both cases, the behavior of the assembly is strongly influenced by the mechanical boundary conditions created by the printed circuit board (PCB) to casing fasteners. In many previously published papers, the conditions imposed to the fasteners are mostly aiming at an increase of the fundamental frequency and a decrease of static or dynamic displacement values characterizing the deformation. These conditions aim at reducing the fatigue in different parts of these assemblies. In the photomechanics laboratory of INSA Rouen, the origins of solder joint failure have been investigated by means of full-field measurements of the flexure deformation induced by vibrations or by forced thermal convection. The measurements were done both at a global level for the whole printed circuit board assembly (PCBA) and at a local level at the solder joints where failure was reported. The experimental technique used was phase-stepped laser speckle interferometry. This technique has a submicrometer sensitivity with respect to out-of-plane deformations induced by bending and its use is completely nonintrusive. Some of the results were comforted by comparison with a numerical finite elements model. The experimental results are presented either as time-average holographic fringe patterns, as in the case of vibrations, or as wrapped phase patterns, as in the case of deformation under thermomechanical stress. Both types of fringe patterns may be processed so as to obtain the explicit out-of-plane static deformation (or vibration amplitude) maps. Experimental results show that the direct cause of solder joint failure may be a high local PCB curvature produced by a supplementary fastening screw intended to reduce displacements and increase fundamental frequency. The curvature is directly responsible for tensile stress appearing in the leads of a large quad flat pack (QFP) component and for shear in the corresponding solder joints. The general principle of increasing the fundamental frequency and decreasing the static or dynamic displacement values has to be checked against the consequences on the PCB curvature near large electronic devices having high stiffness.

Origami for Tight Spaces - 3D 250C PCB Assemblies for Control Systems

2019 ◽  
Vol 2019 (HiTen) ◽  
pp. 000034-000038 ◽  
Author(s):  
Piers Tremlett ◽  
Phil Elliot ◽  
Pablo Tena
Keyword(s):  
High Temperature ◽  
Printed Circuit Board ◽  
Real Life ◽  
Circuit Board ◽  
Calibration Data ◽  
Engine Fuel ◽  
Sensors And Actuators ◽  
Pcb Assembly ◽  
Operational Life ◽  
Mems Technology

Printed circuit board (PCB) assemblies must fit into unusual spaces for many real-life, high temperature applications such as sensors and actuators. This paper details the design and manufacture of a complex control circuit for a jet engine fuel flow valve. “Origami” was needed to fit this control circuitry into the tight space in the valve, this was achieved using a high temperature flex rigid PCB assembly. The valve was mounted on a hot section of the engine, and the assembly was tested for its capability to operate at 178°C and withstand multiple thermal cycles of −55°C and 175°C during its operational life. Various component joining media were investigated to extend the life of the assembly. The project also developed a one-time programmable (OTP) memory aimed at up to 300°C operation for on board memory to provide calibration data or boot memory for high temperature microcontrollers or processors. The device was based on Micro-Electro-Mechanical Systems (MEMS) technology.

scholarly journals A Diffusor/Nozzle Pump Based on a Magnetically Actuated Flexible PCB Diaphragm

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 1077
Author(s):  
Marcus A. Hintermüller ◽  
Bernhard Jakoby
Keyword(s):  
Printed Circuit Board ◽  
Microfluidic Channel ◽  
Circuit Board ◽  
Fabrication Method ◽  
Flexible Membrane ◽  
Printed Circuit ◽  
Magnetically Actuated ◽  
Lorentz Forces ◽  
Out Of Plane ◽  
Flexible Printed Circuit

We present a valveless microfluidic pump utilizing an oscillating membrane made from a flexible printed circuit board. The microfluidic channel is fabricated by a 3D printing process and features diffuser/nozzle structures to obtain a directed flow; the flexible membrane is bonded to the channel. The membrane is actuated via Lorentz forces to accomplish out-of-plane motions and push the fluid through the channel. A permanent magnet provides the static magnetic field required for the actuation. The simple fabrication method can potentially be used for inexpensive mass fabrication for disposable devices.

A Capacitive Fringing Field Sensor Design for Moisture Measurement Based on Printed Circuit Board Technology

2012 ◽  
Vol 61 (4) ◽  
pp. 1105-1112 ◽  
Author(s):  
Robert Neal Dean ◽  
Aditi Kiran Rane ◽  
Michael E. Baginski ◽  
Jonathan Richard ◽  
Zane Hartzog ◽  
...  
Keyword(s):  
Printed Circuit Board ◽  
Circuit Board ◽  
Sensor Design ◽  
Moisture Measurement ◽  
Printed Circuit ◽  
Fringing Field ◽  
Field Sensor

Shock and Vibration of Solder Bumped Flip Chip on Organic Coated Copper Boards

1996 ◽  
Vol 118 (2) ◽  
pp. 101-104 ◽  
Author(s):  
John Lau ◽  
Eric Schneider ◽  
Tom Baker
Keyword(s):  
Mathematical Analysis ◽  
Flip Chip ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Plane Shock ◽  
Printed Circuit ◽  
Flip Chips ◽  
Solder Bumps ◽  
Out Of Plane ◽  
Vibration Tests

The reliability of solder bumped flip chips on organic coated copper (OCC) printed circuit board (PCB) has been studied by shock and vibration tests and a mathematical analysis. Two different chip sizes (7 mm and 14 mm on a side) have been studied, and the larger chips have many internal solder bumps. For the in-plane and out-of-plane and out-of-plane shock tests, the chips were assembled with and without underfill encapsulants. However, for the out-of-plane vibration tests all the chips were underfilled with epoxy.

A PCB Technology Moisture Content and Electrical Conductivity Sensor Probe for Agricultural and Horticultural Applications

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 000984-001011
Author(s):  
Robert N. Dean ◽  
Elizabeth Guertal ◽  
Adam Newby ◽  
Glenn Fain
Keyword(s):  
Electrical Conductivity ◽  
Plant Growth ◽  
Moisture Content ◽  
Test Data ◽  
Printed Circuit Board ◽  
Low Cost ◽  
Circuit Board ◽  
Conductivity Sensor ◽  
Irrigation Volume ◽  
Sensor Probe

Commercial printed circuit board (PCB) technology affords the realization of low-cost sensor probes for agricultural and horticultural applications. Plant growth can be optimized when the soil (in field crop applications) or the substrate (in greenhouse crop applications) properties can be measured and properly adjusted. Two important parameters are moisture content and electrical conductivity. Measuring moisture content allows the grower to better time irrigation for most efficient crop growth. Accurate moisture content measurement also allows the grower to apply sufficient irrigation volume for optimum plant growth while avoiding excessive irrigation volume. Likewise, measuring the electrical conductivity reveals useful information regarding ions in the soil or substrate, which can be used to optimize the application of plant nutrients or manage soil salinity. Commercial soil probes are expensive, which limits their widespread use in commercial applications. PCB probes, on the other hand, can be very inexpensive and can quickly be redesigned to modify the form factor for different applications. These sensors make use of the materials and processes inherent in commercial PCB manufacturing, including the FR4 substrate, patterned Cu cladding and soldermask. The non-conductive E-glass FR4 substrate is used as the rigid backbone of the sensor probe. The patterned Cu cladding is used for electrodes and signal traces. The polymeric soldermask is used as a thin insulating and moisture barrier layer. With these materials, insulated fringing field sensors can be realized on the surface of the PCB to measure moisture content, while exposed metal pads on the surface can be used to measure electrical conductivity. Additionally, the PCB probe is directly compatible with the integration of any desired integrated electronic components. Furthermore, the turnaround time for a new PCB sensor design can be as little as 24 hours at modest cost, making this technology economically superior to traditional sensor technologies, such as silicon based MEMS, where it can take months to realize a new design and be very expensive. A prototype sensor probe has been designed, fabricated and evaluated. Test data is analyzed, compared with test data from traditional sensor probes and presented.

scholarly journals Development of the micro pixel chamber based on MEMS technology

2018 ◽  
Vol 174 ◽  
pp. 02010 ◽  
Author(s):  
T. Takemura ◽  
A. Takada ◽  
T. Kishimoto ◽  
S. Komura ◽  
H. Kubo ◽  
...  
Keyword(s):  
Printed Circuit Board ◽  
Gamma Ray ◽  
Micro Electro Mechanical System ◽  
Neutron Imaging ◽  
Circuit Board ◽  
X Rays ◽  
Position Resolution ◽  
Dose Monitoring ◽  
Mems Technology ◽  
Fine Position

Micro pixel chambers (μ-PIC) are gaseous two-dimensional imaging detectors originally manufactured using printed circuit board (PCB) technology. They are used in MeV gamma-ray astronomy, medicalimaging, neutron imaging, the search for dark matter, and dose monitoring. The position resolution of the present μ-PIC is approximately 120 μm (RMS), however some applications require a fine position resolution of less than 100 μm. To this end, we have started to develop a μ-PIC based on micro electro mechanical system (MEMS) technology, which provides better manufacturing accuracy than PCB technology. Our simulation predicted the gains of MEMS μ-PICs to be twice those of PCB μ-PICs at the same anode voltage. We manufactured two MEMS μ-PICs and tested them to study their behavior. In these experiments, we successfully operated the fabricatedMEMS μ-PICs and we achieved a maximum gain of approximately 7×103 and collected their energy spectra under irradiation of X-rays from 55Fe. However, the measured gains of the MEMS μ-PICs were less than half of the values predicted in the simulations. We postulated that the gains of the MEMS μ-PICs are diminished by the effect of the silicon used as a semiconducting substrate.

Mechanism research of negative resistance oscillations characteristics of the silicon magnetic sensitive transistor with long base region

2018 ◽  
Vol 32 (24) ◽  
pp. 1850261
Author(s):  
Yunjia Bai ◽  
Xiaofeng Zhao ◽  
Jiandong Hao ◽  
Dianzhong Wen
Keyword(s):  
Printed Circuit Board ◽  
Deep Level ◽  
Negative Resistance ◽  
Circuit Board ◽  
Base Region ◽  
Collector Current ◽  
Oscillation Phenomenon ◽  
Mems Technology ◽  
Emitter Region ◽  
P Type

A silicon magnetic sensitive transistor (SMST) with the negative resistance oscillation phenomenon is presented in this paper. The SMST of cubic structure is composed of three regions and three electrodes (E, C and B). Two of the regions (collector region and base region) are designed on the top surface of the SMST, and the emitter region is designed at the bottom of the SMST. Using microelectromechanical system (MEMS) technology, the chip is fabricated on [Formula: see text] orientation p-type silicon (near intrinsic) wafer and packaged on printed circuit board (PCB). When collector voltage (V[Formula: see text]) and the base injecting current (I[Formula: see text]) are a certain value, the experimental results show that the collector current (I[Formula: see text]) attains negative resistance oscillation phenomenon and it is influenced by the external magnetic field (B) and temperature (T). Based on the effect of deep-level impurities on the carrier net recombination rate, theoretical analysis demonstrates that the deep-level impurities are the main factors of the appearance for oscillations phenomenon.

scholarly journals Development and testing of a capacitive digital soil moisture sensor with printed circuit board as a probe

2020 ◽  
Vol 39 (3) ◽  
pp. 911-917
Author(s):  
V. Ogwo ◽  
K.N. Ogbu ◽  
C.C. Anyadike ◽  
O.A. Nwoke ◽  
C.C. Mbajiorgu
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Real Time ◽  
Printed Circuit Board ◽  
Soil Moisture Content ◽  
Gravimetric Method ◽  
Circuit Board ◽  
Moisture Sensor ◽  
Printed Circuit ◽  
Soil Moisture Sensor

The quantity and quality of water present in the soil determine to a greater extent the performance of agricultural crops. Real-time determination of moisture content has a greater advantage over the traditional gravimetric method of determining soil moisture content. Thus, this work was based on the design and construction of a cost effective digital capacitive soil moisture sensor for real-time measurement. The moisture sensors comprised four integrated units namely: power supply unit with a 9V DC battery as a power source, sensor unit with a locally sourced Printed Circuit Board (PCB) as the single sensing probe, control unit made up of PIC16f877 microcontroller programmed with a C language and the C source code compiled in Corporate Computer Services Compiler (CSS C) compiler development environment, and a 16x2 display unit which displays the readings in percentage moisture content (%MC) and capacitance (μF) of the soil obtained from the sensor on its screen. Standard gravimetric moisture content was carried out to get the calibration factor which was used to calibrate the sensor for reliability. The validation was done by taking the reprogrammed (calibrated) sensor to the field for further measurement, after which soil samples were collected for further gravimetric analysis. A regression equation was obtained by plotting the moisture content obtained from gravimetric method (%MCG) against that from sensor reading (%MCS) with a high degree correlation coefficient (R2) of 0.998. The developed capacitive soil moisture sensor is cheap, portable, reliable and easy to use even by local farmers. Keywords: Calibration, Capacitive sensor, Printed circuit board, Soil moisture content, Validation.

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