smta silicon valley chapter june 19 th 2008 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
SMTA Silicon Valley Chapter, June 19 th , 2008 PowerPoint Presentation
Download Presentation
SMTA Silicon Valley Chapter, June 19 th , 2008

Loading in 2 Seconds...

play fullscreen
1 / 40

SMTA Silicon Valley Chapter, June 19 th , 2008 - PowerPoint PPT Presentation


  • 139 Views
  • Uploaded on

SMTA Silicon Valley Chapter, June 19 th , 2008. Board Level Failure Analysis of Chip Scale Packages Nicholas Vickers, Kyle Rauen, Andrew Farris, Michael Krist, Ronald Sloat, Jianbaio Pan, Ph.D. California Polytechnic State University at San Luis Obispo. Overview. Failure analysis Methods

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

SMTA Silicon Valley Chapter, June 19 th , 2008


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
smta silicon valley chapter june 19 th 2008

SMTA Silicon Valley Chapter, June 19th, 2008

Board Level Failure Analysis of Chip Scale Packages

Nicholas Vickers, Kyle Rauen, Andrew Farris, Michael Krist, Ronald Sloat, Jianbaio Pan, Ph.D.

California Polytechnic State University at San Luis Obispo

overview
Overview
  • Failure analysis Methods
  • Failure analysis results
  • Mechanical testing
  • Conclusions
failure analysis techniques
Failure Analysis Techniques
  • 2 techniques used:
    • Dye Penetrant
      • Exposes cracks cause by drop testing
      • Crack area, and direction
    • Cross sectioning
      • Locates the layer in which the crack occurs
      • Identifies composition of layer cracks occur
results
Results

35%

**Note- Some components show more than one failure mode

pad cratering and electrical failure
Pad Cratering and Electrical Failure

Pad Cratered

Not Pad Cratered

solder fracture failure
Solder Fracture Failure
  • Cross-sectioned solder joint is shown to be cracked near the board side copper pad
solder fracture failure7
Solder Fracture Failure
  • Cross-sectioned solder joint is shown to be cracked near the board side copper pad
  • Copper trace failure also shown (left side)
cracking under pads cratering
Cracking Under Pads (Cratering)
  • Epoxy on the PWB board surface cracked away from the fibers within the board, allowing the copper pad to lift away from the board
cracking under pads cratering9
Cracking Under Pads (Cratering)
  • Epoxy on the PWB board surface cracked away from the fibers within the board, allowing the copper pad to lift away from the board
input output trace failure
Input/Output Trace Failure
  • I/O trace gets stretched when the copper pad lifts away from the PWB
  • If the copper pad lifts far enough away, then ductile failure occurs in the copper trace
i o trace failure
I/O Trace Failure
  • Input/Output (I/O) traces that connect to the daisy-chain ‘resistor’ were often broken
  • Many components had this broken trace and no other identifiable failure

Component side

Board side

failure mode comparison
Failure Mode Comparison
  • I/O Trace and Daisy-chain Trace failures are both caused by pad cratering
  • Pad cratering was present on 88% of electrically failed components, and is directly responsible for 69% of electrical failures
failures after 10 drops no eb
Failures After 10 Drops (No EB)

Component: Green – no failure, Blue – transitional failure, Orange – full failure, Red – complete failure

Solder Joints: Black – pad crater, Red – solder fracture (board side), Yellow – solder fracture (csp side)

failures after 14 drops no eb
Failures After 14 Drops (No EB)

Component: Green – no failure, Blue – transitional failure, Orange – full failure, Red – complete failure

Solder Joints: Black – pad crater, Red – solder fracture (board side), Yellow – solder fracture (csp side)

failures after 325 drops epoxy eb
Failures After 325 Drops (Epoxy EB)

Component: Green – no failure, Blue – transitional failure, Orange – full failure, Red – complete failure

Solder Joints: Black – pad crater, Red – solder fracture (board side), Yellow – solder fracture (csp side)

failures after 279 drops acrylic eb
Failures After 279 Drops (Acrylic EB)

Component: Green – no failure, Blue – transitional failure, Orange – full failure, Red – complete failure

Solder Joints: Black – pad crater, Red – solder fracture (board side), Yellow – solder fracture (csp side)

mechanical testing of boards
Mechanical Testing of Boards
  • Need to know material properties of the board to simulate using FEA methods.
  • Tested along fiber direction using an Instron tensile tester.
along fiber results
Along Fiber Results

σ fracture

Elastic Region

Fibers Unkinking

conclusions
Conclusions
  • Pad cratering is the most common failure mode
  • Pad cratering does not necessarily cause electrical failure, but can cause electrical failure by introducing other failure modes
  • Dominance of pad cratering indicates that solder joints are not the weakest part of this lead-free assembly
conclusions cont
Conclusions (Cont.)
  • Tougher board material is needed to increase reliability
  • Majority of failures occurred on the cable side of the board when DAQ cable is attached
  • First failures usually occur in the corners of the CSPs
  • Edge-bonding is effective at reducing pad cratering problems
acknowledgements
Acknowledgements
  • Cal Poly: Michael Krist, Kyle Rauen, Micah Denecour, Andrew Farris, Ron Sloat, and Jianbaio Pan, Ph.D.
  • Flextronics: Dongkai Shangguan, Ph.D., Jasbir Bath, David Geiger, Dennis Willie
  • Henkel: Brian Toleno, Ph.D., Dan Maslyk
acknowledgements27
Acknowledgements
  • Project Sponsors:
  • Office of Naval Research (ONR)

Through California Central Coast Research Park (C3RP)

  • Society of Manufacturing Engineers Education Foundation
  • Surface Mount Technology Association Silicon Valley
dye stained solder fractures
Dye Stained Solder Fractures
  • Dye stained solder fractures were found
    • Partial solder fracture (left) was not completely fractured before the component was removed
    • Complete solder fracture (right) was fully fractured before the component was removed
test vehicle drop orientation
Test Vehicle Drop Orientation
  • Test vehicle is always mounted with components face down
component locations
Component Locations
  • JEDEC defined component numbering
    • The DAQ cable attaches near component C6 (in between components C1 and C11)
blank pwb no cable vs cable
Blank PWB – No Cable vs Cable
  • Symmetry of acceleration peaks has shifted (C7 vs C9)
  • Maximums greatly reduced by cable (C3, C13, C8)

1500G Input Acceleration

populated pwb no edge bond
Populated PWB – No Edge Bond
  • Dampening due to the cable seems less significant than with blank PWB (both graphs are more similar)

1500G Input Acceleration

epoxy edge bonded csps
Epoxy Edge Bonded CSPs
  • Stiffer board with edge bonding has less symmetry disturbance
  • Overall accelerations are significantly reduced vs no edge-bond

1500G Input Acceleration

acrylic edge bonded csps
Acrylic Edge Bonded CSPs
  • Stiffer board with edge bonding has less symmetry disturbance
  • Overall accelerations are significantly reduced vs no edge-bond

1500G Input Acceleration