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Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
3.9 Electronic Testing
Dr. Tarek A. Tutunji
Philadelphia University, Jordan
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Preview In the previous sequences, seven design steps were
discussed.
In this sequence, Electronic Testing will be presented.
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Company Goal Ultimate goal of any company is to maximize its long-
term profit
Quality “fit to use” is a tool to reach its goal
Electronic testing is essential to quality improvement
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
What is Electronic Testing The Process of verifying the functionality of electronic
assemblies
The objective of testing is to identify defective products before they reach the consumer
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Design Engineer vs. Test Engineer The Design Engineer is responsible for designing the
product and building the Prototypes to meet customer demand
The Test Engineer is responsible for formulating the test procedure and writing the data sheets in order to verify the functionality of the manufactured product during assembly
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Levels of Tests PCB test
Modules test
System test
Module 1 Module 2
System
PCB2PCB1 PCB4PCB3
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
PCB Test In-circuit test
Test for Shorts, Open, and Polarity
Functional test
Full operation test to simulate the conditions that the PCB will face in the field
Signals at Output ports and crucial Test Points are usually measured
80% of failures are due to Shorts and Open
10% of failures are due to failed components
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Modules Test Two or more PCBs tested together as an integrated
unit
Testing at this stage usually checks interface and output signals only
Module 1 Module 2
System
PCB2PCB1 PCB4PCB3
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
System Test Complete System Check before Shipping
The in-depth functional tests of individual circuits is not repeated, but system is required to function under normal power for hours or days
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Burn-in vs. ESS Testing Burn-in test applies thermal, mechanical, and
electrical stresses within the limits that product will face in the field while testing product functionality
Environmental Stress Screening (ESS) test applies extreme conditions beyond the field stresses while testing product functionality
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Testing Strategy Identify the equipment needed for the test such as
scopes, function generators, DVM, Computers, test boxes, … etc
Define the Attributes to be tested. What is to be tested? Voltage, Power, Current, Frequency, … etc
Define the specifications. What are the pass and fail levels of each attribute tested
All the above should be part of a well-defined and documented test procedure
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Testing Strategy Well Organized Data Sheets should be used to record
the test results of each electronic assembly
It should include the part and serial number of the assembly tested
These are essential for Quality Management Control and Failure Analyses
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Testing Under Stress The test should be carried under different stresses
such as
Thermal Cycle
Thermal Stress
Mechanical Vibration
Mechanical Shock
Electrical Power Cycling
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Testing Under Stress The Functional Test should be carried out while the
assembly is under the stresses
It is advisable to combine different stresses simultaneously in order to induce possible field failures
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Automatic Testing Use Automatic Test Equipment rather than manual
testing in order to continuously monitor any functionality failure
This involves the use of PC, DAQ cards, and interface units to connect to the electronic assembly under test
It also involves sophisticated programming. In many cases C++ or LABVIEW is used
Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University
Conclusion Testing Electronic Assemblies is an essential part in
production
Automatic testing gives much better detection than manual testing
Although expensive and time consuming, but the tests are vital to assure product quality. It is much cheaper to catch a failed component at production than in the field
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