Technology Advanced Quality, Fault Worldwide Isolation Analytical Services, Techniques Burlington VT for Microelectronics Packaging Dave Vallett PeakSource Analytical, LLC Fairfax, Vermont, USA
Purpose Highlight the importance of rapid problem solving during technology development, manufacturing, and end-user service Summarize the challenges of non-destructive localization of electrically active faults in dense assemblies Review techniques and recent advancements IBM Research 5/5/15 D. Vallett, PeakSource Analytical, LLC 2
Outline Introduction Microelectronic package fault isolation challenges Limitations of acoustic and X-ray imaging Methods EOTPR electro-optical terahertz pulsed reflectometry Lock-in thermography Magnetic current imaging Summary and Conclusions 5/5/15 D. Vallett, PeakSource Analytical, LLC 3
Fault Isolation - the Most Critical Step Development failures, yield loss, field returns Failure Analysis Verification & characterization Fault isolation Deprocessing Inspection Physical & chemical analysis 5/5/15 D. Vallett, PeakSource Analytical, LLC 4
Density Challenges in NDE Package-on-Package IBM Research Sub-surface imaging limited by opacity, absorption, thickness, heterogeneous materials, numerous interfaces Physical imaging alone (e.g. X- ray, acoustic) leaves electrically active defects indistinguishable from inert anomalies Needle in haystack challenge 5/5/15 D. Vallett, PeakSource Analytical, LLC 5
Acoustic, X-ray Image only Physical Structure Active defects, anomalies, structures, interfaces imaged simultaneously (2D or 3D) No definitive causality with electrical failure mode Subsequent analysis (e.g. cross-section, SEM) time-consuming, expensive, not definitive, destructive Precise, accurate, non-destructive fault isolation required 5/5/15 D. Vallett, PeakSource Analytical, LLC 6
Isolating Electrically Active Faults TeraHertz TDR Lock-in Thermography Sensor Magnetic Current Imaging 5/5/15 D. Vallett, PeakSource Analytical, LLC 7
Time Domain Reflectometry TDR / EOTPR (P. Perdu, EUFANET / IPFA 2012) Package conductors have transmission line characteristics Defects alter characteristic impedance Opens: cracks notches, resistive films, etc. Shorts: extra conductor material, foreign material, etc. Impedance changes cause reflections Reflection time correlates to distance Electro-optical TeraHertz pulsed reflectometry (EOTPR) significantly improves resolution 5/5/15 5/5/15 D. Vallett, D. Vallett, PeakSource Analytical, LLC LLC 8
EOTPR Cracked Substrate Trace Resolution / accuracy < 10 um (P. Perdu, EUFANET / IPFA 2012) 5/5/15 D. Vallett, PeakSource Analytical, LLC 9
EOTPR Flip-Chip Open Circuit 83 um (P. Perdu, EUFANET / IPFA 2012) 5/5/15 D. Vallett, PeakSource Analytical, LLC 10
Lock-in Thermography (LIT) Images surface thermal gradient from sub-surface heat source Pulsed source with lock-in amplification Signal depth derived from phase delay Absolute depth using thermal diffusion constants Relative depth using reference heat source(s) Resolution: single microns Sensitivity: micro-watts 5/5/15 D. Vallett, PeakSource Analytical, LLC 11
Thermal Phase-delay Estimates Defect Depth (H. Deslandes, DCG Systems) 5/5/15 D. Vallett, PeakSource Analytical, LLC 12
LIT BGA Pin Short, Fused Bond Wires (H. Deslandes, DCG Systems) 5/5/15 D. Vallett, PeakSource Analytical, LLC 13
LIT Depth Estimation in Stacked Die 13-ohm pin-pin short Fwd-biased diodes as depth references Depth correlates with phase-shift (H. Deslandes, DCG Systems) 5/5/15 D. Vallett, PeakSource Analytical, LLC 14
Magnetic Current Imaging (MCI) Sensor Magnetic field from buried currents propagates freely to the surface Magnetic permeability relative to free space Al 1.000022 Si 0.999996 Cu 0.999990 W 1.000068 Pb 0.999982 Scanned magnetic sensor maps field distribution Magnetic field data converted to current density image High current density or abnormal current paths indicate defect location Resolution: single microns Sensitivity: nano-amps / femto-watts 5/5/15 D. Vallett, PeakSource Analytical, LLC 15
MCI Leadframe Pin-Pin Shorts (J. Gaudestad, Neocera) 5/5/15 D. Vallett, PeakSource Analytical, LLC 16
MCI PLCC / Flex Cable Shorts 5/5/15 D. Vallett, PeakSource Analytical, LLC 17
MCI - Plane-to-Plane MLC Short short (J. Gaudestad, Neocera) 5/5/15 D. Vallett, PeakSource Analytical, LLC 18
Power Short in Fully Assembled PCB Short (J. Gaudestad, Neocera) 5/5/15 D. Vallett, PeakSource Analytical, LLC 19
MCI Subtle Leakage Analysis in PCB Fail Good 5/5/15 D. Vallett, PeakSource Analytical, LLC 20
MCI - Open Circuits Magnetic field from standing wave current vanishes at open circuit location 5/5/15 D. Vallett, PeakSource Analytical, LLC 21
Broken Copper Trace in Substrate (J. Gaudestad, Neocera) 5/5/15 D. Vallett, PeakSource Analytical, LLC 22
Open Failure in the Die Region (J. Gaudestad, Neocera) 5/5/15 D. Vallett, PeakSource Analytical, LLC 23
Summary 5/5/15 D. Vallett, PeakSource Analytical, LLC 24
Conclusions 5/5/15 D. Vallett, PeakSource Analytical, LLC 25