In-Circuit Testing

In-Circuit Testing discusses what an in-circuit test (ICT) is and what it can and cannot do. It answers many questions on how tests are actually carried out, with the benefits and drawbacks of the techniques. The emphasis throughout is towards practical problem solving, and many of the examples used are of surface mount printed circuit boards (PCBs).
The book contains separate chapters on application-fitting ICT into a typical test strategy and into the manufacturing environment. The buying decision is fully explored-choice of system, initial and ongoing costs, and preparation of the financial proposal to Management. Then, assuming the automatic test equipment (ATE) has been purchased, additional chapters are devoted to: programming problems and solutions, interfacing problems and solutions, fault diagnosis and fault finding tools. Design for in-circuit test also merits a chapter. This covers specific design guides and the constraints which need to be placed on designers to ensure that ICT is cost effective. The concluding chapter reviews the purchase and use of the chosen ICT with the benefit of hindsight; it covers cost effectiveness; looks at alternative methods of testing, programming, and interfacing; and alternative ways of costing the testing service.
This book is written for potential purchasers and users of in-circuit automatic testers who are attracted to the concept of ICT, but who may need help. This includes Test Engineering Managers who need guidance on which equipment to buy for a given application (and how to financially justify the purchase), and ATE Programmers, Test Engineers and Technicians who would welcome practical advice on how best to use the chosen ATE.

Inhalt

Preface
Abbreviations
1 Introduction
1.1 What is ICT?
1.2 What does ICT do?
1.2.1 Three tasks
1.2.2 Logic testing
1.2.3 Two, four and six wire measurements
1.2.4 Track integrity tests
1.3 What does ICT not do?
1.3.1 Functional testing
1.3.2 Complex VLSI test
1.3.3 High accuracy testing
1.3.4 Full speed testing
1.3.5 Parametric testing
1.4 How does ICT work?
1.4.1 Interfacing
1.4.2 Programming
1.4.3 Test sequence
1.4.4 Node forcing
1.5 What faults can be found by ICT?
1.5.1 Detectable faults
1.5.2 Accessibility
1.5.3 Fault identification
1.6 ICT of surface mounted assemblies
1.7 ICT ATE suppliers
1.7.1 Range of companies supplying ICT ATEs
1.7.2 Specific equipment
1.7.3 Supplier addresses
1.8 References
2 Application
Preamble
2.1 A typical application
2.2 The wrong use of ICT
2.3 The correct use of ICT
2.4 ICT in the test strategy
2.5 Fitting ICT into manufacturing
2.6 Buying an ICT equipment
2.6.1 Choices available
2.6.2 Matching a system to your business
2.6.3 Specmanship
2.7 Cost of ownership/LCC
2.7.1 Net capital cost
2.7.2 Programming cost
2.7.3 Fixture cost
2.7 4 Labor costs
2.7.5 Yearly maintenance costs
2.7.6 Design related costs
2.8 Additional factors
2.8.1 Points for ICT
2.8.2 Points against
2.8.3 General points
2.9 The financial decision
2.10 Presenting the justification to management
2.10.1 Capital expenditure request
2.10.2 Back-up data
2.11 Break-even table
2.12 References
3 Programming - procedures, problems and solutions
3.1 Introduction
3.2 Standard procedures
3.3 The standard program
3.4 Software
3.4.1 Programming language
3.4.2 Software tools
3.5 Guarding
3.6 Programming requirements
3.6.1 Track integrity tests
3.6.2 Passive components
3.6.3 Active components
3.6.4 Integrated circuits
3.7 Programming workstations
3.8 Summary
4 Interfacing - procedures, problems and solutions
4.1 Introduction
4.2 The ATE
4.3 The basic fixture
4.4 The test probe
4.5 Drilling the platten
4.6 Wiring the fixture
4.7 Problems
4.7.1 Drilling inaccuracies
4.7.2 Intermittent contact
4.7.3 Modifications
4.7.4 Noise and crosstalk
4.7.5 Resistance and reactance
4.7.6 Parallel paths
4.7.7 Choosing the best position for the probe
4.7.8 ATE limitations
4.7.9 Special access problems
4.8 Fixture maintenance
4.9 Vacuum pumps
4.10 Summary
4.11 References
5 Fault diagnosis
Preamble
5.1 Short circuits
5.2 Open circuits
5.3 Faulty analogue components
5.4 Assembly faults
5.5 Faulty digital components
5.6 Faults generated in test
5.7 Rework and repair stations
5.8 Summary
5.9 References
6 Designing for in-circuit test
6.1 General
6.2 Mechanical design of the PCB
6.3 Formal rules for testability
6.3.1 Access
6.3.2 Bed-of-nails access
6.3.3 ATE
6.3.4 Component identification
6.3.5 Avoidance of select-on-test
6.3.6 Minimize adjust-on-test
6.3.7 Noise and crosstalk
6.3.8 Fault diagnosis
6.3.9 Use test engineering skills
6.3.10 Built in self test (BIST)
6.3.11 Double-sided access
6.3.12 IC sockets
6.4 Mechanical requirements
6.4.1 Maximum board dimensions
6.4.2 BUT location
6.4.3 PCB/fixture interfacing
6.4.4 PCB coatings
6.5 CAD aspects
6.6 Design for test checklist
6.7 References
7 Conclusion
7.1 Analyzing the strategy
7.2 Refining the strategy
7.3 Cost effectiveness
7.4 Fault analysis and feedback
7.5 ICT and yield
7.6 Boundary scan
7.7 Automatic board handlers
7.8 Real time fault analysis
7.9 Computer integrated test
7.10 Test area management
7.11 Conclusion
7.12 References
Index