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Athira seminar

my seminar on moisture measurement s unique

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Athira seminar

  1. 1. WELCOME8/3/2013 DEPT ECE,SNMIMT,Maliankara 1
  4. 4.  Moisture is the amount of water in any form in a material It is a component of molecular makeup for all material Excessive or deficient moisture adversely impact the physicalproperties of a materialINTRODUCTION8/3/2013 DEPT ECE,SNMIMT,Maliankara 4Moisture Measurement
  5. 5. BLOCKDIAGRAM MeasurementPrimaryAir ovenSecondaryDestructive Non-DestructiveInterdigital capacitor Ultracapacitor8/3/2013 DEPT ECE,SNMIMT,Maliankara 5Moisture Measurement
  6. 6. MOISTURE MEASUREMENT INSIDEELECTRONIC DEVICESUSING ULTRACAPACITOR Ultracapacitor:Electrochemical capacitor with relatively highenergy density Lack of dielectric permits packaging of plates with largesurface area into a given volume Formed of ordinary activated carbon electrodes8/3/2013 DEPT ECE,SNMIMT,Maliankara 6Moisture Measurement
  7. 7. CONTD… No liquid electrolyte exists inside the device Electrodes are placed on both sides of a layer of poroussilicon Potassium hydroxide in powder form is embedded insideporous silicon Useful for monitoring moisture penetration inside smallelectronic devices8/3/2013 DEPT ECE,SNMIMT,Maliankara 7Moisture Measurement
  8. 8. CONTD… As moisture penetrates the porous silicon layer, a liquidelectrolyte starts to form Presence of moisture causes:• Conductivity of electrolyte increases• Hence the capacitance of the ultracapacitor increases• Results in high capacitance8/3/2013 DEPT ECE,SNMIMT,Maliankara 8Moisture Measurement
  9. 9. CONTD…Ultracapacitor (dry, without electrolyte) (with electrolyte)8/3/2013 DEPT ECE,SNMIMT,Maliankara 9Moisture Measurement
  10. 10. CONTD…8/3/2013 DEPT ECE,SNMIMT,Maliankara10Capacitance with relative humidity (5-80)% of MC causes (0-17) μFMoisture Measurement
  11. 11. MOISTURE MEASUREMENT OF SKIN Importance: Needed for the identification and prevention ofECZYMA Method adopted for skin moisture measurement:capacitancemethod(Interdigital Capacitor)Mild case of eczyma8/3/2013 DEPT ECE,SNMIMT,Maliankara 11Moisture Measurement
  12. 12. CONTD… Stratum corneum is the outermost layer of the skin It is composed of dead skin cells, a protein calledKeratin, naturally secreted oils Dry skin exhibits a lack of oils results in cracking of thestratum corneum8/3/2013 DEPT ECE,SNMIMT,Maliankara 12Moisture Measurement
  13. 13. CONTD…8/3/2013 DEPT ECE,SNMIMT,Maliankara 13Stratum corneumMoisture Measurement
  15. 15. CONTD…INTERDIGITAL CAPACITOR: IDC is the core component in capacitance method It contains thin strips of copper Moisture is measured as proportional increase in capacitance8/3/2013 DEPT ECE,SNMIMT,Maliankara 15Moisture Measurement
  16. 16. CONTD… SCATTERFIELD EFFECT:• Deviation of the linear path from one plate to the other• Important concept in the design of an IDC8/3/2013 DEPT ECE,SNMIMT,Maliankara 16Moisture MeasurementInterdigital capacitance
  17. 17. CONTD…CAPACITANCE MEASURING CIRCUIT: Circuit to measure the increase in capacitance is required “Add on capacitance meter” is used for the purpose Add on capacitance circuit is used to identify capacitors of therange 1pF to 100pF8/3/2013 DEPT ECE,SNMIMT,Maliankara 17Moisture Measurement
  18. 18. CONTD…8/3/2013 DEPT ECE,SNMIMT,Maliankara 18Add on capacitance circuitMoisture Measurement
  19. 19. CONTD…8/3/2013 DEPT ECE,SNMIMT,Maliankara 19 Circuit charges the test capacitor via a resistor selected by therotary switch Circuit charges the largest capacitor (in the range) in exactly100 units of time Voltmeter works only when the pin 6 of 74c14 IC is low Voltmeter gives the reading corresponding to the testcapacitanceMoisture Measurement
  20. 20. CONTD…MICROCONTROLLER : Project incoporates AVR butterfly microcontroller It has an ADC converter built in, labelled as Voltage V_in Microcontroller takes data from the ADC port (V_in) andperforms the conversion It produces a value of 0 on the display when the device isturned on and IDC is exposed to air8/3/2013 DEPT ECE,SNMIMT,Maliankara 20Moisture Measurement
  21. 21. CONTD…8/3/2013 DEPT ECE,SNMIMT,Maliankara 21AVR butterfly microcontroller kitMoisture Measurement
  22. 22. RESULTSKIN TYPE VALUE DISPLAYED ON LCDMoist skin 10-12Normal skin 4-9Dry skin 1-38/3/2013 DEPT ECE,SNMIMT,Maliankara 22
  23. 23. CONTD…8/3/2013 DEPT ECE,SNMIMT,Maliankara 23Complete circuit of moisture sensorMoisture Measurement
  24. 24. MOISTURE MEASUREMENT IN PCBEFFECTS OF MOISTURE IN PCB : Moisture reduces the quality of lamination and solder Excessive moisture increases dielectric constant leading tochanges in circuit switching speed Ionic corrosion causes electrical open circuit or short circuit High levels of residual moisture in PCBs causes delaminationduring soldering8/3/2013 DEPT ECE,SNMIMT,Maliankara 24Moisture Measurement
  25. 25. CONTD… Moisture enters the PCB when the partial pressure of themoisture is greater to that inside the PCB Focused on capacitance measurements to follow theabsorption and desorption behaviour of moisture Capacitance is dependent on permitivity (which is dependenton moisture)8/3/2013 DEPT ECE,SNMIMT,Maliankara 25Moisture Measurement
  26. 26. DELAMINATED PCB8/3/2013 DEPT ECE,SNMIMT,Maliankara 26Moisture Measurement
  27. 27. EXPERIMENTAL SETUP Test boards are designed with capacitors situated on innerlayers between external copper planes It is placed in 85°C and 85 per cent relative humidity (RH)environment Moisture removal at bake temperatures of 80, 110 and 125°Cis monitered Capacitance is periodically measured at a frequency of 100kHz8/3/2013 DEPT ECE,SNMIMT,Maliankara 27Moisture Measurement
  28. 28. 8/3/2013 DEPT ECE,SNMIMT,Maliankara 28(a)Test board showing plated and non-plated through holesat different densities (b) Illustration of the internal gridcapacitorsDimensioned capacitor designMoisture Measurement
  29. 29. CAPACITANCE MEASURED8/3/2013 DEPT ECE,SNMIMT,Maliankara 29Effect of non-PTH hole density on average capacitance decrease for the test boards baked at (a)80°C, (b) 110°C and (c) 125°CMoisture Measurement
  30. 30. CONTD…8/3/2013 DEPT ECE,SNMIMT,Maliankara 30Comparison of PTH and non-PTH on the capacitance decrease with bake time at 125°C forthree hole densitiesMoisture Measurement
  31. 31. CONTD… Average capacitance decreases more quickly for higher holedensities due to the increase in surface area Capacitance decreases faster for boards with non-PTH suchboards require shorter bake time PTH boards have a smaller exposed surface area than non-PTH boards so moisture cannot escape so easily8/3/2013 DEPT ECE,SNMIMT,Maliankara 31Moisture Measurement
  32. 32. MODELLING PTH AND NON-PTH INCOPPER PLANES Modelling is done to compare different moisture desorptioncapability of PTH and non-PTH boards during a baking Model boards are subjected to stimulated baking Model consisted of a PCB with a 0.4 mm hole repeatedinfinitely in both x and y directions and with a pitch of 4 mm Extra model was created to represent copper planes on innerlayers only8/3/2013 DEPT ECE,SNMIMT,Maliankara 32Moisture Measurement
  33. 33. CONTD…8/3/2013 DEPT ECE,SNMIMT,Maliankara 33(a) Non-PTH with copper plane on outer layers, (b) PTH with copper plane on ouer layers and(c) PTH with internal copper planesMoisture Measurement
  34. 34. MODELLED MOISTURE PROFILE :8/3/2013 DEPT ECE,SNMIMT,Maliankara 34Modelled moisture profile (a) non-PTH with copper plane on outerlayers, (b) PTH with copper plane on outer layers and (c) PTH withinternal copper planesMoisture MeasurementCONTD…
  35. 35. CONTD… Dark blue colour represents saturation and light yellow as dryregions Moisture exits non-PTH PCB model more quickly as moisturecan escape more easily from the greater open surface area For PTH board, rate of moisture loss is slower as moisturemust diffuse a greater distance to find surface free fromcopper For boards with internal copper planes moisture rapidly existsfirst,then becomes slow8/3/2013 DEPT ECE,SNMIMT,Maliankara 35Moisture Measurement
  36. 36. CONTD…8/3/2013 DEPT ECE,SNMIMT,Maliankara 36Modelled effect of bake time on the mean moisture content in the centralregion (1 mm off the copper plane) in boards PTH and non-PTH boards.Moisture Measurement
  37. 37. ADVANTAGESULTRACAPACITOR SKIN MOISTURE SENSORLong life High accuracyLow cost portabilityExtremely low internal resistance inexpensiveHigh output power and Improved safety8/3/2013 DEPT ECE,SNMIMT,Maliankara 37Moisture Measurement
  38. 38. DISADVANTAGESULTRACAPACITOR SKIN MOISTURE SENSORHighest dielectric absorption Difficulty in producing the deviceLow maximum voltage Not a handheld deviceHigh self discharge8/3/2013 DEPT ECE,SNMIMT,Maliankara 38Moisture Measurement
  39. 39. FUTURE SCOPESCOPE OF ULTRACAPACITOR IN PACEMAKER: Pacemaker helps to monitor and control your heartbeat It consists of a battery, a computerized generator, and wireswith sensors at their tips Malfunction can occur if moisture happens to be inside thedevice Ultracapacitor can be used inside the device to check theamount of moisture8/3/2013 DEPT ECE,SNMIMT,Maliankara 39Moisture Measurement
  40. 40. CONTD…8/3/2013 DEPT ECE,SNMIMT,Maliankara 40Pacemaker implanted inside human bodyMoisture Measurement
  41. 41. CONCLUSION8/3/2013 DEPT ECE,SNMIMT,Maliankara 41FoodMedicineIndustryRELEVANCECONCLUSION7/2/2013 DEPTOF ECE,SNMIMT,Maliankara 42Moisture Measurement
  42. 42. CONTD… A processed materials MC will define its physical properties atall stages of processing and final product existence Non-destructive methods are preferred andeach methoddiscussed has specific applications Moisture analysis means testing at the point ofprocessing, and making adjustments before product integrityis effected8/3/2013 DEPT ECE,SNMIMT,Maliankara 42Moisture Measurement
  43. 43. REFERENCE Design of a handheld skin moisture measuring device for applicationtowards eczema, By Scott Truong Moisture measurements in pcbs and impact of design on desorptionbehaviour , Chris Hunt,, National Physical Laboratory, UK N.P. Avdelidis, P. I. Nicholson & P. Wallace, ”Pulsed thermography in theinvestigation of PCBs for defect detection & analysis”, www.ecma-international.org8/3/2013 DEPT ECE,SNMIMT,Maliankara 43Moisture Measurement
  44. 44. 8/3/2013 DEPT ECE,SNMIMT,Maliankara 44Moisture Measurement
  45. 45. 8/3/2013 DEPT ECE,SNMIMT,Maliankara 45Moisture Measurement