Reservoir Structure for Liquid TIM in Lidded Flip Chip Packages
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lidded flip chip packages face challenges in using liquid thermal interface materials (TIM) due to the 'pumping-out' issue, where the liquid metal TIM is expelled under thermal cycling, leading to incomplete gap filling and potential electrical damage, limiting their commercial application.
Innovation Solution
A heat-dissipating object with a reservoir structure, comprising a seal ring, connecting hole, and reservoir, which allows for the liquid TIM to be stored and released as needed, ensuring consistent gap filling between the flip chip and lid, preventing pressure buildup and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid metal TIM is used in conventional lidded flip chip packages, then thermal conductivity and surface wetting capability are improved, but the liquid metal is pumped out under thermal cycling causing incomplete gap filling and potential electrical damage
Solution Approach 1:
The reservoir structure pre-stores liquid metal TIM before thermal cycling begins. When the package undergoes thermal cycling and the gap volume changes, the pre-stored liquid metal in the reservoir can flow into the gap to maintain complete filling, preventing the pumping out effect that would otherwise occur during thermal expansion and contraction cycles
Solution Approach 2:
The reservoir structure acts as a buffer or cushion that compensates for volume changes in the gap during thermal cycling. By having excess liquid metal stored in the reservoir beforehand, the system cushiones against the harmful effect of liquid metal being pumped out, ensuring the gap remains completely filled and preventing electrical damage from exposed conductive elements
2Reliability
If liquid metal TIM is used to fill the gap, then thermal conductivity is improved, but volume changes due to thermal expansion cause pressure buildup and TIM leakage
Solution Approach 1:
The reservoir structure pre-stores additional liquid metal TIM to accommodate thermal expansion. When the package heats up and the gap volume increases, the pre-stored liquid metal flows into the expanded gap space, preventing pressure buildup and leakage while maintaining complete gap filling and optimal thermal conductivity
Solution Approach 2:
The reservoir structure provides a buffer zone that cushions against pressure buildup during thermal expansion. By having extra liquid metal available in the reservoir beforehand, the system can accommodate volume changes without generating excessive pressure, thereby preventing TIM leakage while maintaining high thermal conductivity through complete gap filling
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The reservoir structure maintains a consistent liquid TIM presence, enhancing thermal performance and preventing electrical damage by managing volume changes due to thermal expansion, thus enabling the use of liquid TIM in lidded flip chip packages.
Implementation Method 1
the seal ring is an elastic-type ring mounted on the bottom surface of the base plate
Implementation Method 2
a thermal interface material (TIM) is usually used to fill the gap between the flip chip and a heat-dissipating object, like a lid or a heat sink for transferring the heat from one to the other
Implementation Method 3
when the package is under a thermal cycling test or in its long term of application, the volume of the gap between the flip chip and the lid varies with temperature due to the warpage of the flip chip
Data Source
AI summary
The disclosure describes a heat-dissipating object having a reservoir structure so that a reservoir system can be formed in an electronic device, allowing for a liquid TIM in the gap between the heat-dissipating object and the electronic device. The reservoir structure comprises a seal ring, a connecting hole and a reservoir which is a tube for taking in a liquid material and releasing it again when needed. A heat-dissipating object, including a heat sink, a cold plate and a vapor chamber and an electronic device, including a flip chip package and a lidded flip chip package are particularly described in details of the embodiments of the present invention.