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composites applications in electrical and electronics

  1. 1. Applications of composites in field of electrical and electronics Mechanics of composite materials Assignment GIRISH RAGHUNATHAN 1RV18MMD07
  2. 2. Outline APPPLICATIONS • PCB • Electromagnetic shielding • Electrical switching and insulation • Wearable electronics • Electronic sensors(E NOSE) • Batteries • Lightning Harvester
  3. 3. 1.Printed Circuit Board Fig 1: PCB made from FR4 composite
  4. 4. Fig 2: Function of a dielectric
  5. 5. • A PCB substrate must have good dielectric performance. That is, it must insulate the conductive layers from one another by blocking electrical conductivity, to minimize electrical signal loss, crosstalk between conductive layers and noise. • Technically, that translates into a low dielectric constant (Dk ≤3.7) and a low dissipation factor (Df ≤0.005). • The higher the Dk, the lower the speed of the electrical signal. Df is a measure of the loss in dielectric property, in this case, the insulative capability of the PCB’s composite substrate. • Because signal loss and noise are exacerbated by heat, substrates must contribute to thermal management as well.
  6. 6. • The majority of PCBs are made with E-glass/epoxy prepregs -- the PCB industry's traditional workhorse material, designated "FR-4," is an E-glass/epoxy material -- although other reinforcing fibers, including aramid and quartz, are sometimes used for specialty applications. • Resin alternatives include vinyl ester and polyester, for commodity boards, and cyanate ester, polyimide and bismaleimide triazine (BT) for more demanding, elevated-temperature applications.
  7. 7. • The coefficient of thermal expansion (CTE) of silicon memory chips is 2.5 /°C • CTE of a fiberglass laminate can range from 14 /°C to 24 /°C. • An advantage of aramid as an alternative laminate substrate is its low negative CTE, which reduces thermal stress, as well as its low dielectric constant of 4, compared to 6.2 for E-glass.
  8. 8. 2. Electromagnetic shielding • Electromagnetic shielding principle The effect of electromagnetic shielding is to reduce the electromagnetic field effect in a certain area (not including these sources) generated by some radiation sources, and to effectively control the harm caused by electromagnetic radiation from one area to another.
  9. 9. RISK FROM EM RADIATION • If human beings are exposed to the EM waves, the network of veins in high risk organs such as eyes might be affected. This is due to heat build-up in the eyes by the EM waves which could not be easily dissipated. • In order to avoid these hazards to human beings and to protect the sensitive circuits from undesired EM radiation, EMI shielding is essential.
  10. 10. Fig 3: Electromagnetic shielding mechanism Fig 4: Components of an electromagnetic wave
  11. 11. • The principle of action is the use of low-resistance conductor material, because the conductor material has a reflection and guiding effect on electromagnetic energy flow and within the conductor material. • It create the current and magnetic polarization which is opposite with the source of electromagnetic field, thereby reduce the effect of radiation source in electromagnetic field, normally it represented by shielding effectiveness (SE). • The shielding effectiveness refers to the ratio of the incident or reflection electromagnetic waves without shielding to the reflection or transmission of electromagnetic wave under shielding at the same location, that is, shielding material to the attenuation value of electromagnetic signal, the unit is (dB).
  12. 12. Conductive mechanism of composite conductive polymer • With the increase of the concentration of conductive filler, the conductivity of the polymer increases slowly. When the concentration reaches a certain value, the conductivity increases sharply, the polymer becomes a conductor, and the filler concentration continues to increase but electro conductivity has not changed much. • The conductivity filler concentration at which the conductivity changed abruptly is called the 'diafiltration threshold'. So its conductive mechanism has two main theories: one is the conductive channel theory; the other is the tunnel effect theory. • The conductive channel mechanism plays a major role in the high concentration of conductive filler, which means that when the content of the conductive filler reaches the 'diafiltration threshold', the conductive particles contact each other to form an infinite network. The formation of conductive channels, carriers can freely move within the system. Thereby making the composite conductive. • The tunneling effect plays a major role in the low packing concentration, which means that there is a certain spacing between the conductive particles. Electrons in the thermal vibration under the action of migration form a conductive network. So that the composite polymer becomes conductive.
  13. 13. Fig 5: Conductive path formed in a conductive polymer
  14. 14. • The low frequency signals can be arrested by means of reflection whereas high frequency signals should be arrested by means of absorption which needs much attention. • Much research has been conducted to develop high frequency EM absorbers by means of coating fillers with magnetic materials or incorporation of magnetic materials in the polymer matrix.
  15. 15. • Materials with high absorption co-efficient could impart shielding effectiveness of 80 dB for the frequency of 18 GHz electronic systems has increased enormously in all the engineering and technology fields. The advances in electronics reduces the component size and placing more number of electrical parts in limited space reduces the system size and increases the mobility. • Placing more number of components in a very confined space builds the problem of keeping the electromagnetic interference (EMI) of these systems from interfering with other systems through radiation. • Carbon-Carbon composites have good shield effectiveness of 124 dB in low frequency range of 0.3Mhz to 1.2 Ghz, the dominant mode being reflection.
  16. 16. 3. Electrical switching and insulation Properties that composite materials have include : • Dielectric strength • High thermal conductivity • Low electrical conductivity for insulation • Electromagnetic interference (EMI) shielding effectiveness • Heat resistance • Track resistance • Low coefficient of thermal expansion • Durability to withstand repeated use without a decrease in performance • Moisture resistance for safety and durability • Sound baffling for quieter operation
  17. 17. • Paper-Phenolic Materials Norplex-Micarta offers a variety of paper phenolic sheets. This cost-effective line of products consists of multiple plies of various papers impregnated with phenolic resins and laminated under heat and pressure to produce a thermoset composite. Both papers and resins can be modified to change the finished properties of the final laminate. These products offer thermal, mechanical isolation, and thermal and electrical insulation properties that meet or exceed those of most thermoplastic materials. The properties and cost-effectiveness of these products often make them the insulators of choice in low-voltage, dry-service electrical equipment.
  18. 18. • RTB326 - Epoxy Cotton/Linen Tube Grade RTB326 is a tube made from a fine cotton fabric and an epoxy resin system. It has low moisture absorption and excellent dimensional stability and chemical resistance. Typical uses include bearing retainers and parts that require excellent machining characteristics. • NP509 - Melamine Glass Sheet Woven glass fabric, melamine resin laminate. NP509 is very hard, flame resistant, machining grade with excellent electrical properties in high humidity conditions. NP509 has high physical strength and excellent arc resistance. Meets MIL-I-24768/1 type GME, MIL-I-24768/8 type GMG and IEC 60893-3-3-MF GC 201.
  19. 19. • Paper-Epoxy Materials These products consist of multiple plies of various papers impregnated with specialty epoxy resin systems and laminated under heat and pressure to produce a thermoset composite. Both papers and resins can be modified to change the finished properties of the final product, and once cured, they will not melt like most thermoplastics. Thermoset epoxy composites are ideal for applications ranging from small switch parts to insulating high voltage tap chargers in power transformers, and other applications requiring electrical insulation properties.
  20. 20. • P95TDB-Glass/polyimide P95 consists of woven glass fabric with polyimide resin. The product is engineered to maintain excellent physical properties at 240°C, making it suitable for high temperature applications. It offers a low coefficient of thermal expansion, as well as high mechanical strength and consistent quality. It can be used for structural components, thermal insulators, PCB manufacture and assembly, and high temperature gaskets in petrochemical plants and other applications requiring excellent compressive strength, low moisture absorption, and excellent chemical resistance.
  21. 21. Fig 6: Paper/phenolic sheet Fig 7: glass/melamine sheet Fig 8: cotton/epoxy tubes Fig 9: glass/ polyimide
  22. 22. Applications in the Electrical Industry • The unique properties of thermoset composites make the materials ideally suited to the rigors of use in the electrical industry. • Phenolic-matrix and melamine composites are used in many electronics including printed circuit boards, gears, and insulators. Insulation, circuit boards, and components requiring a high resistance to heat will often be made from a silicone-based composite. Additional applications include: • Control system components • Circuit breakers • Arc chutes • Arc shields • Terminal blocks and boards • Substation equipment • Microwave antennas • Standoff insulators • Pole line hardware • Printed wiring boards • Switchgear • Panelboards • Server rooms • Metering devices • Lighting components
  23. 23. 4. Wearable electronics • Graphene/CNT polymer composites are widely being used to make wearable electronics. • Silver nanofillers in elastomer composite used in wearables. Fig 10: Textile integrated with electronics
  24. 24. Fig 11: Graphene/polymer composite in textile batteries
  25. 25. Fig 12: graphene/polymer composite in wearable SWNT electonics
  26. 26. 5. Electronic sensors • Carbon black polymer odour and flavour sensors for detecting vapours. Used for environmental monitoring to check air quality, crime prevention such as bomb detection, quality control. Reinforcing phase: Dispersed carbon black particles (conc. 2 to 8% by wt.) Reinforcing medium : Polymers ( usually Polystyrene ) Fig 13: Electonic vapour sensor
  27. 27. 6. Batteries Fig 14: Li ion battery
  28. 28. Fig 15: Working of Li ion battery CHARGING DISCHARGING
  29. 29. 7. Satellite electronics mounted on composite panel Fig 16: electronics in satellite
  30. 30. 8. Lightning harvester • GC ltd. plans to adapt the high strength-to-weight characteristics of Graphene based composite technology to manufacture ultra-long cables - of circa 8 miles in length. These ultra-long cables would have a highly-conductive coating of graphene - effectively making them lightning rods which can reach up into the clouds !! • Clouds contain a massive amount of energy, in the form of static electricity, or the difference in voltage between the bottom of a cloud and the ground. Lightning occurs when this voltage difference builds up to such an extent that electricity leaps across this gap.
  31. 31. • GC ltd. believes it could also collect electrical energy from clouds. The highly-conductive graphene coating on a GC composite cable (held aloft by weather balloons) would be, by far, the path of least resistance for electricity to travel along. As Electricity flows - even the extremely large bursts from lightning strikes - would travel down the graphene-coated cable into a super-capacitor array, which could then release electricity into the power grid in a controlled way. • Preliminary estimates indicate that if this design were to work, GC Lightning Harvesters could be deployed at a lower cost than with nearly every other form of electrical power generation - and, crucially, it would be based on an infinitely renewable energy source, i.e. clouds.
  32. 32. THANK YOU