1-AbstractIn oil drilling the earth surface is drilled up to 3-4 km to reach the surface of oil and for all ofthis process we need an earth driller accompanied with a printed circuit board having an electronicsensor circuit which sense and measure all the parameters including temperature, depth,pressure etc. of operational area. These electronic components are mounted on the PCB andthese components with PCB have to sustain the high operational temperature approximately300 C to 600 C at the depth of 3-4 km. Furthermore due to the high friction of drilling, thevibrations are very high. This drilling process at the depth of 3-4 kilometer remains for severalminutes and until that time PCB and electronic components have to bear the high temperatureof 300 C to 600 C and severe vibrations without any damage so the process could becompleted smoothly. In this report we will find out the best possible technologies and materialsto form such a printed circuit board which could sustain operational temperature as well ashigh vibrations for the time of drilling as well as we will search the materials to encapsulatethe electronic components to avoid them from scorching heat.
High Temperature Electronics42-Introduction: Oil Drilling industries searching for electronics components that can operate onworst environment just like high temperatures. In past decades, engineers and technicians hadto rely on active and passive cooling for manufacturing of components that can be operate onhigh temperature and also increase the reliability of the system. Cost is also a factor for designingof components.One of the biggest user of high temperatures electronics devices that have temperature greater than150C is Downhole oil and gas drilling Industry. During oil drilling process, downhole instrumentscollects data around the geological formation. This is called well logging.
It can be measure resistivity,radioactivity, acoustic, travel timing, magnetic resonance and different other properties. All these informationhelps the geologist to make a decision about the type of rocks, types of fluid present alsocollect data about the location. At the production phase electronic system monitor pressure, temperature,vibration, multi-phase flow and actively control valves. To fulfill all these requirements, a completesignal chain of high performance components are required. Reliability of component is the firstpriority because replacement or repair of any electronics components in the deep in the well is very isvery difficult and it takes more than a day also loss of millions dollars per day.
9 Following figureshow schematic drawing of oil drilling.High Temperature Electronics53-Analysis of Problems: In the past, oil drilling maximum operating temperature was 150°C to 175°C butnow a days the oil wells becoming down day by day. So that, the scientist have to design newcomponents that can operate on high temperature and high pressure. Temperature in thesewells are now exceeding more than 200°C and pressure more than 25Kpsi.In the figure belowshows different layer of earth with high temperature and pressure for oil drilling. Main problems in oil drilling isVibrations during the digging process andother is high Temperature. In deepdrilling, well control is complicated bynarrow drilling margins, higher bottomhole pressures, and temperatures.
Applications of tools that can assist inpore pressure prediction are limited by thedepth, temperature, and the high cost oferror.The temperature range of oil and gaswell is up to 200°C wheresas thetepetearture range of geathermal well isup to 450°C. For this high temperature,high pressure and vibartions conditionswe need components that can operate onthis harsh environment.High Temperature Electronics64-Subdivision of Problems: Temperature is a major cause of failure of electronic components and affects thereliability of operation. For example, temperature influences various performance functions inElectronic components. These include the carrier density, energy band gap, carrier diffusion,mobility, current density, velocitysaturation, threshold voltage, andinterconnect resistance. For deep oil & gaswell logging, the electronic modules with inthe logging tool have to pass throughtemperature of 200°C for hours. whereas,typically possible operation temperature ofmost available commercial electronics is nomore than 120°C.
whereas, availablehigh temperature electronic components arevery expensive. In our senario, thermal fig: Downhole logging intrumentation signal chainmanagement is essential to protect heat sensitive electronics from worst thermal environment.In view of the challenge mentioned above, an alternative option is the use of electronicmodules that are specially made for operation at high temperature.The following are the failure mechanisms occurred in electronic components by hightemperature:? Electro-Magiration? Electrical Overstress (EOS)? Thermal Fatigue? Solder joint failure? Ionic effects? Increase in laekage current? Thermal Stress effect on PCB Fig: Thermal stress induced damage in a PCB? Ionic effects & High Temperature Stress MigrationHigh Temperature Electronics75-State of The Art:5.1-Flex-Rigid PCB The combination of Flex Printed circuit and Printed circuit board makes a newproducts that is called Flex-Rigid PCB.It comprises of one or more rigid zones and one ormore flexible zones on a printed circuit board. However after passing through differentprocesses formed circuit board with Flex PrintedCircuit (FPC) characteristics and rigid Printed CircuitBoard (PCB) characteristics.Polyimide is the main material of the rigid flex PCB.
Polyimide is a material that has a good heat dissipationperformance. Polyimide is better than traditionaldielectric materials. Rigid-Flex PCB can be made toany shape and size and fit to any space designaccording to the requirements. They are an integrated hybrid of printed circuit board and flexcircuit technology. They provides a better freedom of packaging geometry and a lessreduction of interconnects and repeatability of printed circuit board (PCB) technology. Theyhave temperate ranges from -200°C to 400°C, Rigid-Flex circuit design has made arevolutional change in last few years. New designs required the rigid area to be fullycomprises of “rigid” boards.
The development of flex board is based on the flexible plate andhigh density multilayer rigid plate on it and has the same place in the process ofmanufacturing. Due to rigid flex PCB use Polyimide material, it has good chemical resistanceto oils, acids, gases etc. The Flex Rigid PCB provides good radiation and UC exposureresistance, that is the biggestreason that it can be used inhigh temperature areas.FlexRigid PCB is multilayeredPCB and it’s layer can beshown in figure. IPC 2223CSectional Design Standard forFlexible Printed Boards. High Temperature Electronics85.2-Silicon On Insulator (SOI) Process IC technology has Recently produced devices that can operate efficiently attemperature with guaranteed that mentioned on data sheet specifications.
Advance technologyis in progress, that is circuit design, and layout techniques. Whereas, standard silicon can beoperated on requirement of 125°C of temperature. Leakage in standard silicon processes tomake it doubles for every 10°C increase to making it unacceptable for manyapplications.Trench isolation, silicon-on-insulator (SOI), and different changes on thestandard silicon process largely decrease in leakage and make high performance operation tothe well above 200°C. Figure 1 depicts Silicon On Insulator bipolar process.
Wide band gapmaterials, such as silicon carbide (SiC). siliconcarbide ICs can be operated at up to 500°C to 600°Cand it can be shown in laboratory investigation.Whereas, Silicon Carbide SiC is an devolpingprocess technology and recently, only few devicesare available like as power switches. Wide band gap(WBG) semiconductors has larger energy bandgap,Beause of this they have ability to operate at muchhigher temperatures than other silicon.
In next few years, WBG semiconductors will bethe material of choice for simultaneous realization of high power and hightemperature applications. SiliconCarbide (SiC) based devices arethe most widely researched widebandgap semiconductor to date forpower switch realization SiCbaseddevices are expected to beable to operate up to 600°C. IBMand AMD has already used SOI inthe microprocessor in 2000 and 2001repectively.
Table shows differenthigh temperature electronicsapplications details.High Temperature Electronics96-Comparison between Flex Rigid Pcb and Silicon On Insulator6.1-Flex Rigid PCB:? Dielectric is thin? Transmission routing is short? Small through hole? Small noise signal,high reliability? Flexible to change shape in specialspace requirement.? Resist high and low temperature andfire.? Can fold and don’t effect the transmission.? Against electrostatic disturbanceDiadvantages:? The fabricated technology has complexed one because it involve Flex PCB and rigidPCB technology and it is complex make at the same time.? The cost of Components are very expensive for both rigid PCB and flex PCB.? In Flex Rigid PCB, one board damages, other one is also unuseful.
6.2-Silicon On Insulator? High temperature compatibility? Smart power integration? Embedded memory integration? Less Power consumption? Greater speed of operation? Reduced Source and Drain to Substrate Capacitance? Lower Passive currentHigh Temperature Electronics107-Our Solution: In process of oil drilling we face two type of problems that are vibrationsand high temperature. We have two types of techniques and material that we can use to get ridof this problem that is Flex rigid PCB and Silicon On Insulator Process. Both of thetechnologies can be operate on high temperature both have temperature range more than500°C. But in our senario we can use Silicon on Insulator process, because Oil Drilling is acomplex process so we required only a flexible and long lasting solution. Silicon carbidedevice technology is being developed for power electronic applications for use at hightemperatures.
Silicon on insulator (SOI) technology gives the ability to realize complexelectronic functions. We can use bulk silicon, SOI, and wide band gap devices to operate onhigh temperature devices.Silicon-On-Silicon-Carbide devices are designed andfabricated to avoid from hard radiation and able tooperate on high temperature. These type of devicesconcepts are the combination of silicon on insulatorand Silicon Carbide. Silicon Carbide SiC is the mostpopular material in the wide band gap Category.
Thiscombination makes a system that efficiently controlthe temperature. Given table shows the wide band gapand other physical properties of different materials.SiC and SOI is Ideal for high temperaturepower devices because of the following reasons: Figure from: 6? high thermal conductivity? high electric field breakdown strength? wide band gap? temperature range greater than 500°C? SiC is durable, cheap, commercial availablewith more than 200 polytypes. High Temperature Electronics11? Cost is less than Flex-Rigid PCB Table given below shows different ranges of temperature of Silicon on Insulatorprocess.
As seen that wide band gap has the highest capacity to operate on high temperature.Our maximum temperature in oil drilling process is 600°C so that Silicon on Insulator can beused in our process of oil drilling. In future, wide band gap semiconductor will be used because of their larger energyband and capable of electronic operation at much higher temperatures than Silicon. WideBand gap Semiconductor will be the first choice for operation of high power and high temperaturedevices.