1-Abstract In oil drilling the earth surface is drilled up to 3-4 km to reach the surface of oil and for all of this process we need an earth driller accompanied with a printed circuit board having an electronic sensor circuit which sense and measure all the parameters including temperature, depth, pressure etc. of operational area. These electronic components are mounted on the PCB and these components with PCB have to sustain the high operational temperature approximately 300 C to 600 C at the depth of 3-4 km. Furthermore due to the high friction of drilling, the vibrations are very high. This drilling process at the depth of 3-4 kilometer remains for several minutes and until that time PCB and electronic components have to bear the high temperature of 300 C to 600 C and severe vibrations without any damage so the process could be completed smoothly. In this report we will find out the best possible technologies and materials to form such a printed circuit board which could sustain operational temperature as well as high vibrations for the time of drilling as well as we will search the materials to encapsulate the electronic components to avoid them from scorching heat. High Temperature Electronics 4 2-Introduction: Oil Drilling industries searching for electronics components that can operate on worst environment just like high temperatures. In past decades, engineers and technicians had to rely on active and passive cooling for manufacturing of components that can be operate on high temperature and also increase the reliability of the system. Cost is also a factor for designing of components. One of the biggest user of high temperatures electronics devices that have temperature greater than 150C is Downhole oil and gas drilling Industry. During oil drilling process, downhole instruments collects 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 information helps the geologist to make a decision about the type of rocks, types of fluid present also collect 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 complete signal chain of high performance components are required. Reliability of component is the first priority because replacement or repair of any electronics components in the deep in the well is very is very difficult and it takes more than a day also loss of millions dollars per day. 9 Following figure show schematic drawing of oil drilling. High Temperature Electronics 5 3-Analysis of Problems: In the past, oil drilling maximum operating temperature was 150°C to 175°C but now a days the oil wells becoming down day by day. So that, the scientist have to design new components that can operate on high temperature and high pressure. Temperature in these wells are now exceeding more than 200°C and pressure more than 25Kpsi.In the figure below shows different layer of earth with high temperature and pressure for oil drilling. Main problems in oil drilling is Vibrations during the digging process and other is high Temperature. In deep drilling, well control is complicated by narrow drilling margins, higher bottom hole pressures, and temperatures. Applications of tools that can assist in pore pressure prediction are limited by the depth, temperature, and the high cost of error.The temperature range of oil and gas well is up to 200°C wheresas the tepetearture range of geathermal well is up to 450°C. For this high temperature, high pressure and vibartions conditions we need components that can operate on this harsh environment. High Temperature Electronics 6 4-Subdivision of Problems: Temperature is a major cause of failure of electronic components and affects the reliability of operation. For example, temperature influences various performance functions in Electronic components. These include the carrier density, energy band gap, carrier diffusion, mobility, current density, velocity saturation, threshold voltage, and interconnect resistance. For deep oil & gas well logging, the electronic modules with in the logging tool have to pass through temperature of 200°C for hours. whereas, typically possible operation temperature of most available commercial electronics is no more than 120°C.whereas, available high temperature electronic components are very expensive. In our senario, thermal fig: Downhole logging intrumentation signal chain management 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 electronic modules that are specially made for operation at high temperature. The following are the failure mechanisms occurred in electronic components by high temperature: ? 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 Migration High Temperature Electronics 7 5-State of The Art: 5.1-Flex-Rigid PCB The combination of Flex Printed circuit and Printed circuit board makes a new products that is called Flex-Rigid PCB.It comprises of one or more rigid zones and one or more flexible zones on a printed circuit board. However after passing through different processes formed circuit board with Flex Printed Circuit (FPC) characteristics and rigid Printed Circuit Board (PCB) characteristics. Polyimide is the main material of the rigid flex PCB. Polyimide is a material that has a good heat dissipation performance. Polyimide is better than traditional dielectric materials. Rigid-Flex PCB can be made to any shape and size and fit to any space design according to the requirements. They are an integrated hybrid of printed circuit board and flex circuit technology. They provides a better freedom of packaging geometry and a less reduction of interconnects and repeatability of printed circuit board (PCB) technology. They have temperate ranges from -200°C to 400°C, Rigid-Flex circuit design has made a revolutional change in last few years. New designs required the rigid area to be fully comprises of “rigid” boards. The development of flex board is based on the flexible plate and high density multilayer rigid plate on it and has the same place in the process of manufacturing. Due to rigid flex PCB use Polyimide material, it has good chemical resistance to oils, acids, gases etc. The Flex Rigid PCB provides good radiation and UC exposure resistance, that is the biggest reason that it can be used in high temperature areas.Flex Rigid PCB is multilayered PCB and it’s layer can be shown in figure. IPC 2223C Sectional Design Standard for Flexible Printed Boards. High Temperature Electronics 8 5.2-Silicon On Insulator (SOI) Process IC technology has Recently produced devices that can operate efficiently at temperature with guaranteed that mentioned on data sheet specifications. Advance technology is in progress, that is circuit design, and layout techniques. Whereas, standard silicon can be operated on requirement of 125°C of temperature. Leakage in standard silicon processes to make it doubles for every 10°C increase to making it unacceptable for many applications.Trench isolation, silicon-on-insulator (SOI), and different changes on the standard silicon process largely decrease in leakage and make high performance operation to the well above 200°C. Figure 1 depicts Silicon On Insulator bipolar process. Wide band gap materials, such as silicon carbide (SiC). silicon carbide ICs can be operated at up to 500°C to 600°C and it can be shown in laboratory investigation. Whereas, Silicon Carbide SiC is an devolping process technology and recently, only few devices are available like as power switches. Wide band gap (WBG) semiconductors has larger energy bandgap, Beause of this they have ability to operate at much higher temperatures than other silicon. In next few years, WBG semiconductors will be the material of choice for simultaneous realization of high power and high temperature applications. Silicon Carbide (SiC) based devices are the most widely researched wide bandgap semiconductor to date for power switch realization SiCbased devices are expected to be able to operate up to 600°C. IBM and AMD has already used SOI in the microprocessor in 2000 and 2001 repectively.Table shows different high temperature electronics applications details. High Temperature Electronics 9 6-Comparison between Flex Rigid Pcb and Silicon On Insulator 6.1-Flex Rigid PCB: ? Dielectric is thin ? Transmission routing is short ? Small through hole ? Small noise signal,high reliability ? Flexible to change shape in special space requirement. ? Resist high and low temperature and fire. ? Can fold and don’t effect the transmission. ? Against electrostatic disturbance Diadvantages: ? The fabricated technology has complexed one because it involve Flex PCB and rigid PCB 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 current High Temperature Electronics 10 7-Our Solution: In process of oil drilling we face two type of problems that are vibrations and high temperature. We have two types of techniques and material that we can use to get rid of this problem that is Flex rigid PCB and Silicon On Insulator Process. Both of the technologies can be operate on high temperature both have temperature range more than 500°C. But in our senario we can use Silicon on Insulator process, because Oil Drilling is a complex process so we required only a flexible and long lasting solution. Silicon carbide device technology is being developed for power electronic applications for use at high temperatures. Silicon on insulator (SOI) technology gives the ability to realize complex electronic functions. We can use bulk silicon, SOI, and wide band gap devices to operate on high temperature devices. Silicon-On-Silicon-Carbide devices are designed and fabricated to avoid from hard radiation and able to operate on high temperature. These type of devices concepts are the combination of silicon on insulator and Silicon Carbide. Silicon Carbide SiC is the most popular material in the wide band gap Category. This combination makes a system that efficiently control the temperature. Given table shows the wide band gap and other physical properties of different materials. SiC and SOI is Ideal for high temperature power 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 available with more than 200 polytypes. High Temperature Electronics 11 ? Cost is less than Flex-Rigid PCB Table given below shows different ranges of temperature of Silicon on Insulator process. 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 be used in our process of oil drilling. In future, wide band gap semiconductor will be used because of their larger energy band and capable of electronic operation at much higher temperatures than Silicon. Wide Band gap Semiconductor will be the first choice for operation of high power and high temperature devices.