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

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.

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.

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 © HDP User Group International, Inc.

Digital Speckle Correlation

Digital Speckle Correlation © HDP User Group International, Inc.

Digital Speckle Correlation © HDP User Group International, Inc.

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)

© 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” © HDP User Group International, Inc.

© 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.

© 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 © HDP User Group International, Inc.

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

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