Electronic product design and development

Product Design and

DevelopmentAn 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


• 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


• 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


• 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.


1. 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.


• 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


•• Customer’s requirementCustomer’s requirement must be correctly translatedcorrectly translated in to the the technical technical specificationspecification of a product that can be profitably realized by the supplier of such a product (hence forth referred as Manufacturer).


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.


Selling price

Costing 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

– Taxes


• 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.


• 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.


• 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 To this extent, R&D as well as Production departments are responsible for economic departments are responsible for economic success of a manufacturing firmsuccess of a manufacturing firm.


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


Engineering prototype

• Environmental tests

• modifications may be carried out

• If major changes � another Engineering

Prototype

• This closes the first phase of product design.


• 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.


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.


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


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





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.


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.


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.


Bathtub Curve

t1 t2

S1

S2

Time

Failure Rate Wear-outFailure

EarlyFailure

Useful Life

Operating stress S2 > S1


• 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.


• 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.


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-


PartFailure Rate

%/1000 hrsMain Failure Mode

Carbon Composition Resistors 0.0015 Open circuit, Parameter change

Carbon Film resistors 0.002 Open Circuit, Parameter change

Wire wound resistors 0.015 Short circuit

Electrolytic capacitors 0.008 Short circuit, Open circuit

Parameter change, Excessive leakage

Solid Tantalum 0.001 Short circuit, Open circuit


Tantalum foil 0.005 Short circuit, Open circuit


Diodes 0.0036 Short circuit, Open circuit,

High reverse current

Transistors 0.018 Low gain, Short circuit, Open circuit,

High leakage collector-base

Transformers and chokes 0.020 Short circuit, Open circuit,

Insulation failure

Motors 0.050 Short circuit, Open circuit,

Insulation failure

Switches 0.020 Short circuit, Open circuit

Relays 0.030 Coil/ Contact burn-out


• 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


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.

∑=

=

n

1i

itN

1MTTF

∑

∑

=

=

ii

ii

n

1MTTF

and

n rate Failure System

λ

λ


Example: A trigger circuit of single phase SCR consists of

following 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 (λλλλi)

Transistors 8 0.61

Diodes 10 0.20

Resistors 21 0.60

Capacitors 4 0.60

Pulse Transformers 1 0.15

Small Transformers 1 0.20

Solution: 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 for

106 hours.

=

∑=

=

n

1i

itN

1MTTF


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


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


• 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,


Packaging 1st

DigitProtection Against Foreign

Objects2nd

DigitProtection Against Moisture

0 Not protected 0 Not protected

1 Protected against objects greater than 50mm

1 Protected against dripping water

2 Protected against objects greater than 12mm

2 Protected against dripping water when tilted up to 15N

3 Protected against objects greater than 2.5mm

3 Protected against spraying water

4 Protected against objects greater than 1.0mm

4 Protected against splashing water

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 submersion IP Codes:

Example: IP 55 would indicate a dust protected (first digit 5) piece of

equipment which is protected against water jets (second digit 5)



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 ?


What happen to the circuit under test if

we 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.


• Surge voltage in low voltage AC power circuits describes transient event “Not Exceeding one half period of the normal mains waveform duration”


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.


• 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.)


• 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


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.


Fundamental characteristics of electrical circuit

R1 R2 R3

L

N

R1 = low, I1= Highest

R3-High, I3=Lowest


Transient Solution L

N

To load

R

Very

High

Transient

During Normal operation of circuit R is very high

For Transient duration of time R value is very less � provides path to current


High Frequency Noise Solution

• 2 types of filters

– Series filter

• Inductor, Chock

• Due to series connection drawbacks

– Parallel filters

• Capacitor

• Bidirectional capabilities


Transzorb(Transient voltage suppressor)


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 transients


• Fuses

– works on Melting principal


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


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


Separate Analog & Digital ground

(Why)

• Analog circuit are more sensitive to noise


It is sensible to separate analog & digital

circuitry to prevent Digital noise from corrupting

analog performance.

Separation of Power supplies also.

(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)


Thermal Management

• P = V I

• 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


Power Dissipation

1) Static 2) Dynamic

• Static Power Dissipation

• PD = VDD * Io

• Causes

– leakage current,

– Sub threshold Current,

– Substrate current


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)

References

1. J. C. Whitaker, “The Electronics Handbook, CRC Press,

IEEE Press

2. Charles A. Harper, “Electronic Packaging and

Interconnection Handbook”, McGraw-Hill Handbooks,

ISBN 0-07-143048-2

3. 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


Thank You…

• Contact Details�

• Prof V K Bairagi, Pune, India

[email protected]


Date post:	29-Nov-2014
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Electronic product design and development

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