Heat Spreaders With Underfill Trenches for Semiconductor Assemblies
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Solution Overview
Problem
Semiconductor device assemblies face challenges in accommodating excess underfill material, which can interfere with the thermal contact between stacked devices and heat spreaders, leading to inadequate heat dissipation and potential damage due to void formation and material buildup.
Innovation Solution
Incorporating trenches in the heat spreader design to accommodate excess underfill material, allowing for effective thermal and physical attachment to semiconductor devices and substrates while preventing void formation and ensuring efficient heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excess underfill material is present in the semiconductor device assembly, then the underfill provides adequate bonding and void prevention, but the underfill interferes with thermal contact between stacked devices and heat spreader
Solution Approach 1:
The heat spreader is segmented by introducing trenches that divide the contact surface into distinct regions. These trenches create separate zones for underfill material accommodation and thermal contact, allowing the underfill to bond devices without interfering with the thermal interface between the heat spreader and semiconductor devices.
Solution Approach 2:
The harmful effect of excess underfill material is extracted by providing dedicated trenches that isolate the underfill from the thermal contact regions. The underfill is effectively 'taken out' from the thermal pathway by confining it to specific trench areas, preventing it from interfering with heat transfer while maintaining its bonding function.
2Temperature
If trenches are added to the heat spreader to accommodate underfill, then thermal contact is improved, but device complexity increases
Solution Approach 1:
The heat spreader maintains a simple overall structure with trenches added only in specific local regions where underfill accommodation is needed. The majority of the heat spreader surface remains unchanged, preserving simple manufacturing processes while locally introducing complexity only where necessary to solve the thermal contact problem.
3Strength
If underfill material builds up around semiconductor devices, then bonding is strengthened, but void formation occurs and heat dissipation is reduced
Solution Approach 1:
The trenches segment the underfill material into controlled regions, allowing strong bonding within trench boundaries while preventing uncontrolled buildup that would create voids and impede heat transfer. The segmentation creates clear separation between bonding zones and thermal contact zones.
Solution Approach 2:
The potential harm of underfill buildup is converted into a benefit by directing the excess underfill into trenches where it can strengthen bonding without creating harmful voids. The trenches transform what would be a harmful interference into a beneficial bonding enhancement in controlled locations.
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 solution effectively reduces component temperatures by up to 35.5°C, enhancing thermal management and preventing damage from excessive underfill material interference, thereby improving the reliability and performance of semiconductor device assemblies.
Implementation Method 1
When in use, semiconductor devices and semiconductor device assemblies generate significant heat. When thermal management techniques used to conduct heat away from semiconductor devices are inadequate...
Implementation Method 2
U.S. Pat. No. 7,439,617, issued Oct. 21, 2008, titled 'CAPILLARY UNDERFLOW INTEGRAL HEAT SPREADER,' discloses a heat spreader including solder wettable material, which may be located in a concavity formed in a mating surface of the heat spreader, which may be melted and pulled by capillary action through a narrow space between a chip and the heat spreader to avoid void formation.
Data Source
AI summary
Heat spreaders for dissipating heat from semiconductor devices comprise a contact surface located within a recess on an underside of the heat spreader, the contact surface being configured to physically and thermally attach to a semiconductor device, and a trench extending into the heat spreader adjacent to the contact surface sized and configured to receive underfill material extending from the semiconductor device into the trench. Related semiconductor device assemblies may include these heat spreaders and methods may include physically and thermally attaching these heat spreaders to semiconductor devices such that underfill material extends from a semiconductor device into the trench.