Electronic product design and development


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Electronic product design and development

  1. 1. Product Design and Development An overview of product development stages: Study of techno-commercial feasibility of specifications (Case study), R & D prototype, Assessment Of reliability (case study), Ergonomic and aesthetic design considerations, Pilot Production batch, QA testing of, products (verification of specifications), Packaging and storage. Estimating power supply requirement (power supply sizing), Study of power supply protection devices: Line filters, Transzorbs, MOVs, Fuses and Suppressor capacitors, Noise reduction, grounding, shielding and guarding techniques, Thermal management. Prof. V. K. Bairagi , SAE UNIT I: Introduction to Product Design and Development• An overview of product development stages• Electronic products can be classified in at least three categories – Consumer products – Industrial products – Military products• classification based on User ??• Important differences in characteristics and specifications Prof. V. K. Bairagi , SAE
  2. 2. • Consumer products – characterized by low cost – Specifications are almost fixed for a range of products – cheap and reliability is not very good – there are no user serviceable parts within it.• Industrial products – offer a higher performance level – designed for specific application or user’s requirements – Cost is high and reliability required is also high – user serviceable part @ site of installation Prof. V. K. Bairagi , SAE • Military products • demand highest level of reliability. • They are very expensive compared to other two categories. • For this grade of products, it is normally not desirable to service the parts at site. Type of product Operating temperature range Consumer 0 - + 70 0C Industrial -25 - +85 0C Military -55 - +125 0C Prof. V. K. Bairagi , SAE
  3. 3. • The characteristics of three types of electronic products being different,• The product development stages are strategies are also different.• We will consider product development stages for a typical industrial grade product.• The reason for doing this is an industrial product represents a large portion of total electronic products. Prof. V. K. Bairagi , SAE1. Identifying the customer requirements• Product development typically starts by identifying- – what the customer wants• User may be looking for – automating the existing industrial process – expanding his current manufacturing capabilities. Prof. V. K. Bairagi , SAE
  4. 4. • Understand the requirement: Marketing or sales person, who are in contact with such potential customer, should understand the requirement thoroughly.• Proper solution A number of meetings are required to correctly understand the process and arrive at a proper solution.• A proper solution is the one that is techno-commercially acceptable to both buyer and supplier of the product Prof. V. K. Bairagi , SAE• Customer’s requirement must be correctly translated in to the technical specification of a product that can be profitably realized by the supplier of such a product (hence forth referred as Manufacturer). Prof. V. K. Bairagi , SAE
  5. 5. 2. Judging the techno-commercial feasibility of the product • After finalizing Technical Specs. – (Acceptable to both User & Manufacture). • R&D team will do a paper design. • The paper design should be close to the final design. • R&D will then prepare a provisional Bill Of Material (BOM). • & Hand it over to costing department. Prof. V. K. Bairagi , SAE Selling priceCosting department will work out the from available data Various factors to consider – Materials cost – Procurement costs – Labor cost – Manufacturing overheads – Marketing overheads – Warranty cost – Cost of service calls – Contingency – Profit margin Prof. V. K. Bairagi , SAE – Taxes
  6. 6. • The proposed selling price, once approved by management will be communicated to Consumer in the form of quotation.• There may be some quantity discounts.• There may be negotiations meeting.• Consumer will then place a firm Purchase Order (PO) with the manufacturer. Prof. V. K. Bairagi , SAE • PO specifies• Description/ Model number quoted by manufacture,• Quantity to be supplied,• Time schedule of supply,• Terms and conditions of payment, inspection clauses etc.• Manufacturer is expected to acknowledge the receipt of PO and accept the terms and conditions.• This step implies that the product is techno- commercially acceptable to both customer and manufacturer. Prof. V. K. Bairagi , SAE
  7. 7. • For the manufacturer,• The economic success depends upon the teamwork.• It is not the marketing department that is solely responsible for profitable product.• Time-to-market is extremely critical.• This is especially true for low-tech products. The competition can soon build up if the product is introduced in the market with delay.• To this extent, R&D as well as Production departments are responsible for economic success of a manufacturing firmfirm. Prof. V. K. Bairagi , SAE 3. Designing the product• Designed to specifications – paper design – prototyping with acceptable method(s), – development of R & D prototype – product documentation (usable by production department)• R & D prototype is thoroughly tested for technical and functional specifications• Field trials• May requires some design modifications• Engineering prototype Prof. V. K. Bairagi , SAE
  8. 8. Engineering prototype• Environmental tests• modifications may be carried out• If major changes another Engineering Prototype• This closes the first phase of product design. Prof. V. K. Bairagi , SAE• Once the field trials are over• (Satisfying the Design Engineer)• Product Documentation is prepared• & handed over to production department• Production department will undertake the making of a small batch of units (typically 5 units)• This batch is known as Pilot Production Batch. Prof. V. K. Bairagi , SAE
  9. 9. 4. Pilot Production Batch• The main purpose of making a pilot product batch is to weed-out marginal design problems.• MARGINAL DESIGNS WILL FAIL IN THE FIELD. Prof. V. K. Bairagi , SAE 5. Environmental Testing• Units from pilot production batch• Various tests are standardized and they specify the severity levels.• The manufacturer is free to select severity level (Has to give indication)• Testing authority will certify the tests Prof. V. K. Bairagi , SAE
  10. 10. 6. QA testing• Once the production department and• R & D are sure of the design meeting the specification• test results data on pilot batch units Quality Assurance department.• They are the final authority to declare the product has passed all the tests• random check Prof. V. K. Bairagi , SAE Prof. V. K. Bairagi , SAE
  11. 11. Prof. V. K. Bairagi , SAEProf. V. K. Bairagi , SAE
  12. 12. SPICE Modeling• Powerful tool for predicting the performance of analog circuits.• However Models omits REAL_TIME effects• No Model can simulate all parasitic effects of discrete components & PCB layout.• Advice Prototype must be build & proved before production.• SPICE models of analog circuits are published by manufacturers. (macro models only simulates major features).• SPICE models are approximate models. Prof. V. K. Bairagi , SAE Reliability• Reliability is the probability that a system will perform its specified function in a give environment• quality over time and environmental conditions• The reliability definition emphasizes – Probability, – Intended function – Time and Operating Conditions. Prof. V. K. Bairagi , SAE
  13. 13. Failures• A failure is the partial or total loss or change in those properties of a device or system in such a way that its functioning is seriously impeded or completely stopped.• Failure mechanisms are physical processes by which the stress can damage the material included in the product.• Investigating failure mechanisms helps in increasing the reliability of the designed product. Prof. V. K. Bairagi , SAE Bathtub CurveFailure Rate Early Wear-out Failure Failure Operating stress S2 > S1 S2 S1 Useful Life Time t1 t2 Prof. V. K. Bairagi , SAE
  14. 14. • There is a large number of failures initially• Infant Mortality or Early life Failure• The failure rate decreases with time• These failures are primarily due to manufacturing defects, weak parts, poor insulation, bad assembly, poor fits etc• Since defective units are eliminated during the initial failure period, this period is known as- Debugging Period or Burn-in period• After this infant mortality period, for a long interval of time, the failures are reported, but it is difficult to determine their cause. Prof. V. K. Bairagi , SAE• They occur due to sharp change in the parameters that determine the performance of the units,• Random failures or Catastrophic failures• This is the period of normal operation• As the time progresses, the units get outworn• When the performance of the product goes beyond the admissible limits, the product fails• This region is called as Wear-out region• ( To be identified by using highly accelerated test conditions)• Modern ICs do not reach wear-out region when operated under normal use conditions. Prof. V. K. Bairagi , SAE
  15. 15. Causes of failure • Components used have incorrect resistance, impedance, voltage, current, capacitance, or dielectric properties. These are called as- Electrical Overstress (EOS) failures. • Due to improper shielding for EMI or due to Electrostatic Discharge (ESD). • Improper Thermal Management causes thermal failures • The most commonly used measure of reliability for ICs is the failure rate expressed in %/1000 hrs. Table below gives representative failure rates for electronic components- Prof. V. K. Bairagi , SAE Failure Rate Part Main Failure Mode %/1000 hrsCarbon Composition Resistors 0.0015 Open circuit, Parameter changeCarbon Film resistors 0.002 Open Circuit, Parameter changeWire wound resistors 0.015 Short circuitElectrolytic capacitors 0.008 Short circuit, Open circuit Parameter change, Excessive leakageSolid Tantalum 0.001 Short circuit, Open circuit Parameter change, Excessive leakageTantalum foil 0.005 Short circuit, Open circuit Parameter change, Excessive leakageDiodes 0.0036 Short circuit, Open circuit, High reverse currentTransistors 0.018 Low gain, Short circuit, Open circuit, High leakage collector-baseTransformers and chokes 0.020 Short circuit, Open circuit, Insulation failureMotors 0.050 Short circuit, Open circuit, Insulation failureSwitches 0.020 Short circuit, Open circuit Prof. V. K. Bairagi , SAERelays 0.030 Coil/ Contact burn-out
  16. 16. • If the time interval is small, the failure rate is called- Instantaneous Failure Rate. [F(t)] or “Hazard rate”. If the time interval is long (such as total operational time) the failure rate is called “Cumulative Failure Rate”.• Mean Time Between Failures (MTBF) – basic measure of reliability for repairable items. – It can be described as the number of hours that pass before a component, assembly, or system fails. – MTBF = (1,000,000 hours) / (2 failures) = 500,000 hours Prof. V. K. Bairagi , SAE Mean Time To Failure (MTTF)• measure of reliability for non-repairable systems• It is the mean time expected until the first failure of a piece of equipment.• Technically MTBF should be used only in reference to repairable items, while MTTF should be used for non-repairable items.• However, MTBF is commonly used for both repairable and non-repairable items. System Failure rate = ∑ n i λi n 1 and MTTF = ∑ ti N i =1 1 MTTF = Prof. V. K. Bairagi , SAE ∑ n iλi
  17. 17. Example: A trigger circuit of single phase SCR consists offollowing components with failure rates shown in table below.Determine overall failure rate and MTTF of the trigger circuit. Component Number used (ni) Failure rate for 106 hours (λi) λ Transistors 8 0.61 Diodes 10 0.20 Resistors 21 0.60 Capacitors 4 0.60 Pulse Transformers 1 0.15 Small Transformers 1 0.20Solution: Failure rate of trigger circuit = Sum of failure rates of all components= = (8 x 0.61) + (10 x 0.2) + (21 x 0.6) + (4 x 0.6) + (2 x 0.2) + ( 1 x 0.15) = 23.78 for106 hours.= 1 n MTTF = N ∑t i =1 i Prof. V. K. Bairagi , SAE Reliability calculation IC Failure rate doubles after every 10degree rise in Temp (Internal temp of IC) Suppose that We build a system with m component , each with different R Sys= R1(t). R2(t). R3(t). R4(t). R5(t). R is the real number between 0 & 1 Prof. V. K. Bairagi , SAE
  18. 18. Ergonomic & Aesthetic Considerations• Ergonomics was another name for Human Factors• Refers to designing work environments for maximizing safety and efficiency.• 2 factors – Interface design • Product must be easy to use • Pleasing to user – Workspace safety Prof. V. K. Bairagi , SAE• Key for business to stay competitive is that to finding right balance between productivity, quality & Safety.• Ergonomics Objectives – To reduce down • Time off work due to injury • Workers compensation completes • Cost of production• Ex: Key board, Mobiles• Man-Machine-Environment system• Factors to consider• Weight, Size, Shape, Surface color, Texture, Corners & Edges of body, Prof. V. K. Bairagi , SAE
  19. 19. Packaging 1st Protection Against Foreign 2nd Protection Against Moisture Digit Objects Digit 0 Not protected 0 Not protected 1 Protected against objects greater 1 Protected against dripping water than 50mm 2 Protected against objects greater 2 Protected against dripping water than 12mm when tilted up to 15N 3 Protected against objects greater 3 Protected against spraying water than 2.5mm 4 Protected against objects greater 4 Protected against splashing water than 1.0mm 5 Dust protected 5 Protected against water jets 6 Dust tight 6 Protected against heavy seas 7 Protection against the effects of immersion 8 Protection against submersionIP Codes:Example: IP 55 would indicate a dust protected (first digit 5) piece of Prof. V. K. Bairagi , SAEequipment which is protected against water jets (second digit 5) Prof. V. K. Bairagi , SAE
  20. 20. Power supply protection• Power supply is the basic need of any electronic system.• Some circuit woks on DC power supply & some on AC power supply.• All of the circuit required power supply at specific voltage & current ratings as specified by manufacture Now the basic question is Why we require power supply protection ? Prof. V. K. Bairagi , SAEWhat happen to the circuit under test ifwe give excess of the voltage & current than requirement ?• Probably the circuit may sustain that excess of Voltage & Current for some time & After that the circuit may gates heated up & finally starts malfunctioning or completely dead.• (But this is rear in day today life)• Surge Voltage is major issue, when we are taking about P.S. protection. Prof. V. K. Bairagi , SAE
  21. 21. • Surge voltage in low voltage AC power circuits describes transient event “Not Exceeding one half period of the normal mains waveform duration” Prof. V. K. Bairagi , SAE When we rub plastic scale on woolen cloth, it will attract small piece of paper• Transient may be periodic or random events.• May appear in any mode (any combination of line, Neutral or Ground conductors).• Transient voltage & current occurs in microseconds.• Transient are of very short duration & Thus acts as a high frequency signal of large voltage & current magnitude. Prof. V. K. Bairagi , SAE
  22. 22. • Lighting is the one of the cause for spicks.• In day to day life operation, utilities will generate significant Transient from power factor correction or grid switching.• Static charge on the overhead utilities conductors resulting from wind can generate a transient if static buildup is sufficient to produce discharge.• Transient are produces during switching.• ( high voltage switches are to be operated at lower speed.) Prof. V. K. Bairagi , SAE • High frequency electronic signal riding on 60 / 50 Hz sine wave can cause digital equipment & sensitive load to malfunction. • Types of high frequency Noise : – Ring Waves ( Building distribution system) – Other types of noise (within equipment itself) • SMPS • Personal computers – Conducted Noise – Back propagation Prof. V. K. Bairagi , SAE
  23. 23. Controlling Transient• Electric signal complete close loop path through load.• If electric signal generated between P-N the signal is bound to take a close loop path from Phase – Neutral – source• If the electric signal is forced so as to take close loop path not returning to source – (P N force to Ground)• The signal will rise the voltage on undesired path unit. Prof. V. K. Bairagi , SAE Fundamental characteristics of electrical circuit L R1 R2 R3 N R1 = low, I1= Highest R3-High, I3=Lowest Prof. V. K. Bairagi , SAE
  24. 24. Transient Solution L To load R Transient Very N HighDuring Normal operation of circuit R is very highFor Transient duration of time R value is very less provides path to current Prof. V. K. Bairagi , SAE High Frequency Noise Solution• 2 types of filters – Series filter • Inductor, Chock • Due to series connection drawbacks – Parallel filters • Capacitor • Bidirectional capabilities Prof. V. K. Bairagi , SAE
  25. 25. Transzorb (Transient voltage suppressor) Prof. V. K. Bairagi , SAE Others types• MOVs – Metal Oxide Varistors – MOVs are semiconductors – These clamping devices contain a matrix of zinc oxide grains sandwiched between two metal plates which serve as electrodes – Higher voltages trigger the avalanche effect and cause the diode junctions to break down – They have high resistance at low voltages and a low resistance at high voltages – MOV degrade as they absorb repeated Prof. V. K. Bairagi , SAE transients
  26. 26. • Fuses – works on Melting principal Prof. V. K. Bairagi , SAE Noise reduction, Grounding,Shielding and Guarding techniques• Factors to be consider While packaging – Compliance with National & International EMC regulation. • (FCC in US, • Internationally CISPR 22 &IEC 1000-4 for emission &immunity control• Emission &immunity control. (2 parts) – Conducted ( on Hard wire ) – Radiated (Radio wave coupling). EMI Prof. V. K. Bairagi , SAE
  27. 27. Shielding• One principal method of dealing with EMI is to shield the source, Victim or both• Types of Shielding – Component shielding – PCB shielding – Shielding at box level or Housing level Prof. V. K. Bairagi , SAESeparate Analog & Digital ground(Why)• Analog circuit are more sensitive to noise Prof. V. K. Bairagi , SAE
  28. 28. It is sensible to separate analog & digitalcircuitry to prevent Digital noise from corruptinganalog performance.Separation of Power supplies also. Prof. V. K. Bairagi , SAE(Both Gnd Must be joined at some common point) Ground Planes• One entire side or layer• Minimum resistance• GP solves many ground impedance problem but Not All ( Because of some resistance & Inductance) Prof. V. K. Bairagi , SAE
  29. 29. Thermal Management• P=VI• P= V*V / R• To minimize power consumption ??? – Reduce V – Or ??? – ( EX of CMOS circuits , 3V )• But …. – Due to reduction of V, The difference between line & ground decreases…. – Effect on performance – But still accepted in Mobiles, deep space application, wireless internet Prof. V. K. Bairagi , SAE Power Dissipation 1) Static 2) Dynamic• Static Power Dissipation• PD = VDD * Io• Causes – leakage current, – Sub threshold Current, – Substrate current Prof. V. K. Bairagi , SAE
  30. 30. Dynamic Power Dissipation • Due to capacitive switch of logic gates • The energy delivered by source • ED= VDD * VDD * C • Average CMOS power consumption Pdyn = ( 0.5 * C * Vdd * Vdd ) (α* f ) (Approx 90% of total) • To reduce Pd – We can reduce Vs, C, (α*f ) – (Note 3 parameter are completely orthogonal) & Cannot be optimized independently) Prof. V. K. Bairagi , SAE References1. J. C. Whitaker, “The Electronics Handbook, CRC Press, IEEE Press2. Charles A. Harper, “Electronic Packaging and Interconnection Handbook”, McGraw-Hill Handbooks, ISBN 0-07-143048-23. Norman Fuqua, “Reliability Engineering for Electronic Design”, Marcel Dekker INC.4. Electronic Instrument Design, Architecture for life cycle, Kim R. Fowler, Oxford University Press Inc.5. Handbook Of Analytical Instruments- R. S. Khandpur, Tata McGraw Hill Prof. V. K. Bairagi , SAE
  31. 31. Thank You…• Contact Details• Prof V K Bairagi, Pune, India bairagi1@gmail.com Prof. V. K. Bairagi , SAE