Compliant Interconnects for Flip Chip Assembly
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Solution Overview
Problem
Flip chip packaging technologies face mechanical stress-induced interconnect failures and compromised electrical performance due to thermal mismatch between semiconductor substrates and dies, particularly in high-frequency RF applications, where additional adhesive materials can negatively impact RF circuit performance.
Innovation Solution
The implementation of compliant interconnects, such as elastomer pins, to replace traditional copper pillars or solder bumps, combined with a support structure that extends beyond the die footprint to secure the semiconductor die to the substrate, eliminating the need for adhesives and ensuring mechanical robustness and reliable electrical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional copper pillars or solder bumps are used for interconnects, then electrical coupling is achieved, but mechanical stress from thermal mismatch causes interconnect failures
Solution Approach 1:
The patent changes the material parameter of the interconnect from rigid copper pillars or solder bumps to compliant elastomer pins. This material parameter change allows the interconnect to deform elastically under thermal stress, preventing mechanical failure while maintaining electrical coupling. The elastomer pins can compress and expand with thermal cycling, resolving the contradiction between reliability and mechanical strength.
Solution Approach 2:
The patent employs composite material structures where elastomer pins are integrated with conductive elements to create interconnects that combine mechanical compliance with electrical conductivity. This composite approach allows the interconnect to simultaneously achieve flexibility for stress relief and sufficient electrical performance, resolving the contradiction between reliability and strength.
2Stability of the object's composition
If additional adhesive material is applied to fill the space between electronic die and substrate, then mechanical stability is improved, but electrical performance of RF integrated circuit is compromised
Solution Approach 1:
The patent extracts and eliminates the adhesive material from the assembly, replacing its mechanical support function with an external support structure. By removing the adhesive that compromises RF performance while maintaining mechanical stability through the support structure, the patent resolves the contradiction between mechanical stability and electrical performance.
Solution Approach 2:
The patent introduces an external support structure as an intermediary element that provides mechanical stability without interfering with the electrical performance of the RF circuit. This mediator structure supports the die assembly from the outside, eliminating the need for adhesive material between the die and substrate, thus resolving the contradiction.
3Strength
If local fixtures are used to couple electronic die to substrate, then mechanical coupling is achieved, but susceptibility to mechanical stress increases
Solution Approach 1:
The patent changes the mechanical parameter of the coupling from rigid local fixtures to compliant elastomer pins. This parameter change allows the interconnect to deform under stress, distributing mechanical loads and reducing susceptibility to stress-induced failures while maintaining coupling strength.
Solution Approach 2:
The patent introduces dynamic compliance to the mechanical coupling through elastomer pins that can deform elastically in response to applied stresses. This dynamic behavior allows the system to absorb and dissipate mechanical energy, reducing the impact of stress events compared to static rigid fixtures, thus resolving the contradiction between coupling strength and stress resistance.
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 reduces mechanical stress-induced failures and maintains electrical performance by providing a robust, adhesive-free interface that withstands thermal mismatch, ensuring reliable operation in flip chip semiconductor packages.
Implementation Method 1
A plurality of compliant interconnects are disposed between the first surface of the substrate and the second surface of the electronic device. The plurality of compliant interconnects are configured to electrically couple the plurality of first contacts on the first surface of the substrate to the plurality of second contacts on the second surface of the electronic device.
Data Source
AI summary
This application is directed to a semiconductor system including a substrate, an electronic device, a plurality of compliant interconnects and a support structure. The substrate has a first surface and a plurality of first contacts formed on the first surface. The electronic device has a second surface facing the first surface of the substrate, and a plurality of second contacts formed on the second surface. The compliant interconnects are disposed between the first surface of the substrate and the second surface of the electronic device, and are configured to electrically couple the first contacts on the first surface of the substrate to the second contacts on the second surface of the electronic device. The support structure is coupled to the substrate and the electronic device, and extends beyond a footprint of the electronic device. The support structure is configured to mechanically couple the electronic device to the substrate.