Tools that can help identify real-time reliability risks earlier and throughout development as well as during the service life of components are becoming increasingly important. One such tool is a real-time wear and its competing failure cycle reliability/surface quality test in which the module is monitored with a technological inheritance coefficient-chain methodology during surface quality cycling. This test provides immediate real-time failure feedback, enhanced failure signature information, failure resistant mechanism and maximum achievable surface quality/reliability. Actually, today’s electronic module packages can integrate several active and passive components within one device, providing simpler board design, reduced component inventory, maintenance and reduced repair costs. Choices in the module material set, coating deposition conditions, component surface quality variables and substrate considerations all play substantial roles in determining the overall package reliability, its real-time monitoring and they ultimately determine which test methodology would be best to verify component reliability.
Over the past decade, the industry has moved from relying on pass/fail test methods toward using design-for-reliability tests that focus on uncovering and analyzing potential problems at an early stage. A facet of this is the increased emphasis on the test-to-failure approach for certain related tests, such as temperature, pressure, speed, surface hardness, surface roughness, surface wavelength, surface stress cycling and others.
Component Surface Quality and Process Factor Cycling
From the perspective of reliability test, component surface and process stress testing has traditionally been a “pass or fail” test where the stress is induced and functional units are subsequently removed from such stress for verification of post electrical-test functionality. In general, a component surface and process stress profile involves the following parameters:
- High extreme component surface quality condition, (Ymax) and Process condition (Xmax);
- Low extreme component surface quality condition, (Ymin) and Process condition (Xmin);
- Component surface quality condition change (Y), where
- Ramp rates;
- Dwell times at extreme component and process conditions,
- Technological Inheritance Coefficients “a – for component surface quality control” and “b – for process condition control”
The lifetime and reliability of a component module can be significantly affected by these parameters tests can be used to characterize product capability and accelerate failure modes (eg die crack, via crack) during initial technology development, product design verification and product qualification.
The Monitoring of Component Surface Quality and Process Factor Cycling
As an enhancement to existing component and process stress methodologies, implementing monitored daisy-chain parameters in real time during component and process condition stresses can help determine if any intermittent failures are beginning to occur. As a result, designers can be alerted to a failure immediately without the need for post electrical test. A monitoring test includes:
- Event Detection: In order to capture a significant component quality and process condition change in real-time, the event-detection capability called for in monitoring failure testing. The failure mechanism associated with condition stresses tend to be very slow to develop and will not change quickly from passing to failing and back to passing. A switch matrix that can be used for all of the modules under test on the scale of one to maximum (success/pass) and 0 to minimum (failure/fail).
- TC Profile: Any type of component/process condition cycle profile can be used in conjunction with monitored condition testing.
- Reliability Growth/Degradation: The component surface quality and reliability grows to maximum as measured with technological inheritance coefficient form point to point (from 0 to 1), degradation moves from 1 to 0.
Monitored Component Surface Quality and Process Factor Data Analyzed
Once reliability growth and degradation is captured, raw data (channel, resistance, count, time and so forth) can be exported, analyzed and graphed within a software package such as LABVIEW, SAS and others. By capturing failure resistance or reliability data throughout the component life cycle, it is possible to detect failures that first develop at extreme conditions of component/process. In contrast, reliability growth/degradation cycles may need to be measured to detect failures and eliminate it with the help of technological inheritance technique and cost effective maintenance procedures. Reliability monitoring and maintenance with technological inheritance technique is useful during development phases when designers must establish confidence in new packaging technologies and throughout its life-time cycle. The ability to detect a failure at the precise cycle count at which it begins to occur is an advantage for earlier detection as well as for accurate statistical analysis. Detailed data regarding the signature of failure and progression of the failure can be valuable in assisting failure-mode determination and reducing failure-analysis time as well as for the attainment of maximum reliability. Technological Inheritance Coefficients can be used to determine failure, time to failure, life-cycle cost, reliability growth and degradation as well as for the selection of cost effective components and processes.
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