6-Joyce-Board Test Workshop 2005.pdf

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What is Strain?• Strain is a measure of deformation, relative to the initial size.L1L2L2 –L1 = ∆LStrain is calculated using the formula ε = ∆L L / L1* which has no• Strain is calculated using the formulaunits since the lengths cancel out.• When ε = 0.000001, it is called 1 microstrain (µε).6
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
Page 1 and 2: Board Test Workshop 2005Board Flex
Page 3 and 4: Intro to Strain testing• As BGA p
Page 5: How do we measure strain?• We mea
Page 9 and 10: And is less bend mode sensitive•
Page 11 and 12: Strain Limit Determination• Strai
Page 13 and 14: LF Solder vs Tin-Lead Eutectic Sold
Page 15 and 16: Intel® Board Flex InitiativeOvervi
Page 17 and 18: Mobile Components Strain LimitGuida
Page 19 and 20: Test Equipment Requirements• Data
Page 21 and 22: Gage Locations• LGA 775 socket- 2
Page 23 and 24: Demonstration• Flex test run #1
Page 25 and 26: Sample Report25
Page 27 and 28: Gage Locations27
Page 29 and 30: JEDEC 9704• Jedec Spec29
Page 31: Backup31

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