1. Digital Speckle Correlation
Status Update
Member Meeting
Nashville
Project Lead: Thilo Sack (CLS)
Project Facilitator: Laurence Schultz (HDPug)
Sept 2016

2. Digital Speckle Correlation
There are strong interests in understanding the reliability behavior of the stacked microvias, especially the effect of the structure designs such as the number of stacks, the pitch between the vias, and the stacking microvia on/off a buried via, etc.

3. Digital Speckle Correlation
The main reliability challenges have been the microvia separation, interfacial delamination and the copper fatigue failure. Experimental evidence suggests that HDI structures experience different stresses and failure modes during thermal operation, and the challenges become tougher under the Pb-free assembly.

4. Project Descriptive Paragraph
The Digital Speckle Correlation Project is an experimental physics-based study, which will mainly rely on digital speckle method for the measurement of the thermal stress in microvias and surrounding areas. (same principle as shadow moiré only with speckles instead of fringe patterns)
The quantitative measurement of the strain and other deformation kinematic parameters make it possible for a mechanistic-based failure analysis.
Verify if results from digital speckle analysis could have predicted the reliability of known microvia failures
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5. Digital Speckle Correlation

6. Digital Speckle Correlation
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7. Digital Speckle Correlation
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8. Phase 1 Process Flow Sample Selection
(PWB Interconnect / Curtiss-Wright)
Ship to Ryerson University
Sample Prep
(Ryerson U)
Digital Speckle Analysis
Correlation of Results to ATC Tests
Generate Conclusions
Final Report
(Decide on Phase 2)

9. © HDP User Group International, Inc.
Phase 1
Phase 1 of the project will make use of micro-via laminate PWBs which were at opposite ends of the reliability spectrum to see how it correlates to the ATC data from the Multi-Lam project.
Three specific samples will be included in the Phase 1 evaluation:
Hi CTE, 18 layer, 3 stack “off buried”
Lo CTE, 12 layer, via stack “on buried”
Hi CTE, 18 layer, via stack “on buried”
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10. © HDP User Group International, Inc.
Phase 1
Leftover samples of as fabricated multi-lam project PWBs will be prepared for digital speckle correlation testing and then the test method applied to see if it can predict the reversal of some of the failure mechanisms.
If so, this would advance the State of the Art both from a reliability prediction method but also from an evaluation of design trade-offs perspective.
© HDP User Group International, Inc.

11. © HDP User Group International, Inc.
Progress (as of Sept 12, 2016)
Several conference calls have taken place to define scope of project
Samples identified for use by Bill Birch / Ivan Strasnicky
Next Steps
Send samples to Prof. Lu at Ryerson for sample prep and feasibility study
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12. Schedule Project Task When Complete Actual
Samples to Professor Lu at Ryerson University
15/09/2016
Professor Lu contacts Bill to discuss sample prep
22/09/2016
Plan of action
29/09/2016
Samples prepared and potted
06/10/2016
Preliminary data
03/11/2016
Team discussion of preliminary data
17/11/2016
Re-do speckle analysis
30/11/2016
Team discussion of final data
14/12/2016
Initial report
21/12/2016
Final Report
08/01/2017
Submission to HDPug BOD with recommendations
23/01/2017
Completion
31/01/2017 12

13. Interested Members Celestica Curtiss-Wright PWB Interconnect Panasonic
Hitachi
Ryerson University (non-member)