AREA CONSORTIUM REPORTS
The reports below are the results of the research conducted by the Universal Instruments AREA Consortium and its funded University efforts. They have been placed in separate years to facilitate easier searches when looking for keywords. Using the “find” function on your browser may make it easier to find keywords on a given page. Typically the shortcut for that function is “Ctrl-F”.
2025 REPORTS
Accelerated Thermal Cycling of Mixed Microvia-under-Pad Structures
Author: Dr. Jeff Kurish
Abstract:
Via-In-Pad Plated over (VIPPO) geometry is a space saving innovation in circuit board design. Multiply reflowed mixed arrays of VIPPO and non-VIPPO pads are high risk of hot tearing mimicking defects. During reflow temperatures pads without copper vias expand far more than VIPPO pads. Expansion of the PCB in the non-VIPPO applies tensile force on the VIPPO pad solder, separating the intermetallic layer and bulk solder. Herein, the in-process defect has been mitigated through nitrogen atmosphere during reflow. The characteristic lifetime effects of VIPPO/non-VIPPO differential expansion are probed via accelerated thermal aging of VIPPO containing PCB boards.