Digital Image Speckle Correlation 2

This project is a continuation of the Digital Speckle Correlation (DSC) Project, which consisted of a preliminary look at the reliability for on and off-stack buried structures by measuring the strains the structure see going through a reflow process.  The name of the new project has been changed to Digital Image Speckle Correlation 2 (DISC2) for two reasons.  Obviously, it is a continuation of the previous project and the other reason is to not use the DSC acronym, which is more commonly used for Differential Scanning Calorimetry, a technique which has nothing to do with the previous or the new, current project.  The recently completed DSC Project used coupons from the very successful completed Multi-lam Project.  For the DISC2 Project the Team will expand the scope of investigated structures.  

This project will create empirical data which could be used in modelling tools, such as DFR’s Sherlock, CALCE’s SARA or full blown FEM tools such as ANSYS.  The resultant model could predict reliability and give an evaluation of design trade-offs.  The Digital Image Speckle method is much quicker than Accelerated Thermal Cycling, which can take months.

Project stage: 

If you are interested in participating in this project:

Members - Go to the "Subscribe Here" section to the right and select the "Subscribe to space" key.

Non Members - Go to the "Contact" section to the right and select the "Contact project facilitator" key.

Idea Information


Some thoughts on possible avenues to explore in the project include:

  • Effect of distance of the cross-section surface to the point of interest on the measured strains (I.e. how close do you have to be to get meaningful results?)
  • Include 2-4 stack on 12, 18 and 24 Layer PWBs to test repeatability of the Digital Speckle method
  • Back drill reliability
  • A top down look on the caps of buried vias
  • Effect of registration of microvia stacks to the buried vias
  • Effect of horizontal distance between via stacks

Microvia Architecture


 IST testing showed markedly poorer performance for all on-buried vs. off-buried via constructions


 Examples of cracks after iST Testing


Example of DISC Shear Stain Plot Showing Probable Area

for Cracking at the Base of the Microvia Stack Interface

with the Buried Via






 During the Idea Phase the team is open to other interesting ideas.  Consider joining!


Definition Information