6-Joyce-Board Test Workshop 2005.pdf

Strain Metrics• Since Strain is a dimensionless number, a precise metricmust be used to define the test values.• The value is based on careful lab testing and analytical FEAmethods.• Intel® uses a metric called diagonal strain. This metriccorrelates better to solder joint damage, regardless of bendmode, than a many other metrics, including principal strain.The worst case bend mode for rectangular FCBGAcomponents is Spherical bending.• The diagonal strain equation is:Max Diagonal Strain = MAX( |e2| , |e1+e3-e2|)**Defined as the Maximum of the absolute value of either e3, or e1+e3e1+e3-e2e27