TestWay: Design for Test and Test Coverage Analyzer
Traditionally, manufacturing and test constraints are only considered at the end of the layout phase, prior to transfer of the CAD data to production. Due to board complexity, it is now mandatory to consider a validation stage at each step of the design and manufacturing phases. TestWay has been developed to allow users to analyze each stage of the design to delivery workflow. This is achieved by the following stages:
- Design for Component – When the key components are selected, check the ROHS, reliability, defects per million opportunities (DPMO), boundary-scan description language (BSDL) file validation in order to guide component selection.
- Electrical Design for Test – When the schematic sheets are defined, TestWay verifies the testability by conducting electrical rules checking that reflect the Design for Test (DfT) guide lines. These can include standard and customer’s specific checks relating to company requirements.
- Test Point Saving – By simulating the test strategy prior to the layout phase, TestWay helps to minimize the need for physical accesses that are necessary to detect defects aligned to the defect universe. It helps to reduce test point access by 30% to 70%!
- Place the Probes – When the layout is finalized, test probe placement should be optimized according to test strategy definitions. The probe access information can then be used for estimating the test coverage, modeling the cost and calculating the production yield and TL9000 initial return rates.
- Select manufacturing strategy – TestWay estimates test coverage using theoretical models that reflect the capabilities for a wide range of test and inspection strategies, such as: Automated Placement Machines (APM); Automatic Optical Inspection (AOI); Automated X-ray Inspection (AXI); Boundary-Scan Test (BST); Flying-probe Test (FPT); In-Circuit Test (ICT) and Functional Test These models should be tuned to reflect the test and measurement capabilities of each individual target tester.
- Design to Build and Design to Test – TestWay exports CAD data in the native format useable by Assembly machines, Automated Optical Inspection, Automated X-Ray, In-Circuit testers, Flying probe testers and Boundary-Scan testers that is aligned to the simulated strategy. The exported files may include assembly and test programs, input lists, test models, as well as test fixture files used by the target testers. Any files created at the Design to Test stage can significantly reduce the downstream test development and fixture costs.
- Test for Excellence – Once the test and inspection programs have been debugged and released, it is imperative to be able read the completed test program or test report and compare the coverage between the estimated and measured analysis.
- Test for Designability – Test is an important contributor for design improvement, once a feedback loop between production and design has been established, such as a concurrent engineering approach to design and test.