Electronics Conformability Analysis - Testing

Aim

To determine if a proposed test strategy is capable of delivering the required quality of testing.

Overview

  • Manufacture of circuit boards involves a number of processes each of which will have a spectrum of associated defects.
  • The fault simulation methodology implied by current versions of analogue/mixed fault simulators such as ANAFAULT and ANTICS, is best suited to integrated circuit test.
  • Board manufacture poses a number a difficult problems for computer aided test , for example:
    • Simulation CAD data may be limited (or non-existent), unlike ICs.
    • Product lifetimes are quite long in some cases.
    • During a product life components may change one at a time.
  • We are developing extensions to the ANTICS fault simulator for application to board manufacture
  • Board test requires a different set of fault models from those used in IC design, with obvious examples including components inserted with the wrong orientation, and missing components
    • IFA techniques similar to those used for ICs can be applied to board layouts if the properties of possible catastrophic defects are known.
    • An IFA analysis of board tracks may not, however, produce the most effective ordered list of faults.
    • Capability analysis applied to the circuit design can be used to identify potential component parametric problems
    • Capability analysis of the physical design of boards and their manufacturing processes can be used to identify potential faults other than track shorts and opens.
    • Data from these analyses can also be used, after further analysis, to determine process quality orientated ordered fault lists

 

Analysis Flow Diagram

Click the diagram for a Hi-Res Version

Assessing Capability

Capability can be assessed in two main ways,

  1. capability maps as in mechanical engineering
  2. numerical analysis

The numerical analysis method is most suited to electronics, data can be gained by suitable circuit simulation and then analysed to produce the required capability data.

The simulation data can also be used to asses the sensitivity of the circuit to component variation.

 When combined the sensitivity and capability data can be used to produce the process quality orientated ordered fault lists and to produce capability breakdowns. These fault lists can then be used to assess test capability.

 

For further information contact I. M. Bell, J. M. Gilbert or D. R. Johnson