Browse Prior Art Database

Power Ramping Preserves Frangible Interconnection Reliability

IP.com Disclosure Number: IPCOM000115374D
Original Publication Date: 1995-Apr-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Di Giacomo, G: AUTHOR [+6]

Abstract

Disclosed is a method for increasing the cyclical fatigue life of frangible electrical connections between a power-dissipating device and substrate to which it's mounted, by controlling the rate of power dissipation in this device, during both the power-on and power-off portions of the cycle.

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This is the abbreviated version, containing approximately 72% of the total text.

Power Ramping Preserves Frangible Interconnection Reliability

      Disclosed is a method for increasing the cyclical fatigue life
of frangible electrical connections between a power-dissipating
device and substrate to which it's mounted, by controlling the rate
of power dissipation in this device, during both the power-on and
power-off portions of the cycle.

      In a typical embodiment, devices such as semiconductor chips
are electrically connected to a glass-ceramic substrate by an
area-array of solder-comprised C4s (controlled collapse chip
connections).  A cooling mechanism typically removes heat by
conduction from the opposing surface of the chip.  A transient
shear-strain in the C4s is induced upon either of the application or
removal of electrical power, due to the large temperature gradients
then existing between the chip and substrate.  The damage effect of
these transient strains can ultimately cause C4 failure due to
fatigue crack growth, and are dependent on both the amplitude and
pulse-width of these transient shear-strain pulses.  The most severe
damage typically occurs at large DNP (distance-to-neutral-point) C4s,
due to the larger shear-strain-range there existing.

      An alternate embodiment consists of multi-chip modules,
typically connected to organic substrates (e.g., epoxy-glass printed
circuit cards) by frangible SBCs (solder-ball-connections).

      The electrical power to the device is applied or removed
gradually thru a mo...