Heat Sink Mounting Platform for IC Thermal Contact
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Solution Overview
Problem
Existing methods for attaching a heat sink to an integrated circuit often apply excessive pressure to ball grid array solder joints and the PCB, leading to reliability issues and mechanical damage during thermal management, especially when high interfacial pressures are required for effective thermal contact.
Innovation Solution
A robust mounting platform is directly attached to the package substrate, bypassing the PCB, using screw-based or flat-spring-based elements to apply pressure to the heat sink without transmitting it to the BGA solder joints, and incorporating shock absorbers to prevent vibration-induced damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If screw-based elements are used to mount heat sink to PCB, then high interfacial pressure is achieved for satisfactory thermal contact, but BGA solder joints and PCB experience excessive mechanical loading leading to reliability issues
Solution Approach 1:
The mounting structure is segmented into two independent systems: (1) heat sink mounting to package substrate using screw-based elements for high pressure thermal contact, and (2) package substrate mounting to PCB using spring-based elements for mechanical support only. This segmentation isolates the high pressure requirement to the thermal interface while protecting BGA joints from excessive loading.
Solution Approach 2:
The package substrate serves as an intermediary component between the heat sink and PCB. It decouples the mechanical loading paths, allowing the heat sink to apply high pressure to the chip for thermal contact while the spring-based mounting to PCB provides only light mechanical support, preventing force transmission to BGA joints.
2Temperature
If high pressure is applied at HS/chip interface, then satisfactory thermal management is achieved, but mechanical damage occurs to PCB and BGA solder joints
Solution Approach 1:
The mounting structure is segmented into two independent systems: (1) heat sink mounting to package substrate using screw-based elements for high pressure thermal contact, and (2) package substrate mounting to PCB using spring-based elements for mechanical support only. This segmentation isolates the high pressure requirement to the thermal interface while protecting BGA joints from excessive loading.
Solution Approach 2:
Different mounting characteristics are applied locally: screw-based rigid mounting is used only at the heat sink-to-package substrate interface where high pressure is needed for thermal contact, while spring-based flexible mounting is used at the package substrate-to-PCB interface where only light mechanical support is needed, creating localized pressure distribution that avoids mechanical damage.
3Temperature
If heat sink is rigidly mounted to PCB, then thermal contact is maintained, but vibration-induced damage occurs to IC during operation
Solution Approach 1:
Shock absorbers are integrated into the mounting structure to provide beforehand cushioning against vibration-induced shocks. These cushioning elements are positioned to absorb mechanical vibrations during operation, protecting the IC from damage while maintaining thermal contact through the heat sink's thermal conduction path.
Solution Approach 2:
Spring-based mounting elements provide flexible mechanical support that allows for vibration isolation. The spring elements can deform elastically to absorb vibration energy, creating a flexible mounting system that protects the IC from mechanical shocks while maintaining the thermal interface through the rigid heat sink-to-package substrate connection.
4Ease of manufacture
If mounting structure is simplified to attach heat sink directly to PCB, then assembly is easier, but BGA solder joints cannot withstand the pressure required for thermal contact
Solution Approach 1:
The mounting structure is segmented into two independent systems: (1) heat sink mounting to package substrate using screw-based elements for high pressure thermal contact, and (2) package substrate mounting to PCB using spring-based elements for mechanical support only. This segmentation isolates the high pressure requirement to the thermal interface while protecting BGA joints from excessive loading.
Solution Approach 2:
The package substrate serves as an intermediary component between the heat sink and PCB. It decouples the mechanical loading paths, allowing the heat sink to apply high pressure to the chip for thermal contact while the spring-based mounting to PCB provides only light mechanical support, preventing force transmission to BGA joints.
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
This solution allows for high-pressure thermal contact without damaging the BGA solder joints or the PCB, enhancing thermal performance and mechanical reliability while simplifying installation and maintenance.
Implementation Method 1
A robust mounting platform is directly attached to the package substrate, bypassing the PCB, using screw-based or flat-spring-based elements to apply pressure to the heat sink without transmitting it to the BGA solder joints
Implementation Method 2
incorporating shock absorbers to prevent vibration-induced damage
Data Source
AI summary
A method and apparatus is provided for attaching a cooling structure to the surface of an integrated circuit (IC). The attachment of the cooling structure, for example a heat sink, to the IC requires that certain pressure is applied, usually by connecting the cooling structure to a Printed Circuit Board (PCB). However, excess pressure may damage the ball grid array (BGA) that connects the IC to the PCB. Attachment of a cooling structure to the IC package substrate is provided without support from the PCB. In one embodiment, shock absorbers are also attached to the cooling structure and the PCB to prevent undesirable vibration of the heat sink mass from affecting the IC.