During the search for the root cause of a board level failure, all aspects of the product must be revisited and investigated. These aspects encompass design, materials, and workmanship. In this discussion, the failure investigation involved an S-Band Power Amplifier assembly exhibiting abnormally low RF output power where initial troubleshooting did not provide a clear cause of failure. A detailed fault tree drove investigations that narrowed the focus to a few possible root causes. However, as the investigation progressed, multiple contributors were eventually discovered, some that were not initially considered.

Equipment manufacturers have developed peripherals for their tools that add soft defect localization (SDL) capability to existing optical beam tools, in many cases providing excellent results. However, these upgrades add significant cost to the tool. This paper presents the design considerations for a simple adapter that was developed in house to add SDL capability to optical beam induced resistance change (OBIRCH) tool, including resolution of some unexpected problems. This solution represents a simple, low cost method to add SDL testing capability to the OBIRCH tool and can also be used in conjunction with OBIC and XIVA tools with little or no modification. An early example of the SDL results provided by this adapter is also presented.

Comprehensive in situ (designed-in) diagnostic capabilities have been incorporated into digital microelectronic systems for years, yet similar capabilities are not commonly incorporated into the design of analog microelectronics. And as feature sizes shrink and back end interconnect metallization becomes more complex, the need for effective diagnostics for analog circuits becomes ever more critical. This paper presents concepts for incorporating in situ diagnostic capability into analog circuit designs. Aspects of analog diagnostic system architecture are discussed as well as nodal measurement scenarios for common signal types. As microelectronic feature sizes continue to shrink, diagnostic capabilities such as those presented here will become essential to the process of fault localization in analog circuits.

Many manufacturers in the microelectronics industry supply customers who increasingly demand ultra-low product failure rates. However, one of the least desirable scenarios for the microelectronic failure analyst is when analysis is required on a single failed unit. In these cases, the analyst loses the luxury of having “disposable” failing units in the analysis process. In the following discussion we present strategies to help the analyst more effectively find the failure mechanism for single unit failures.