Metal Foam Conductive Posts for Warpage Accommodation
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Solution Overview
Problem
Existing microelectronic components with rigid conductive posts face challenges in accommodating irregularities in circuit boards, such as warpage, and require specialized test sockets, which increase costs and complexity.
Innovation Solution
The use of conductive posts formed from a connected lattice of metal with voids, which provides a lower modulus of elasticity and allows for independent movement, enabling engagement with contact pads despite board irregularities and simplifying testing without specialized sockets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid solid metal posts are used, then electrical conductivity and structural strength are improved, but the ability to accommodate board warpage and irregularities deteriorates
Solution Approach 1:
The patent applies porous metal foam material for the conductive posts instead of solid metal. The metal foam provides a cellular structure with voids that enables compression and deformation, allowing the posts to accommodate board warpage and irregularities while maintaining electrical conductivity and structural integrity through the interconnected metal matrix.
Solution Approach 2:
The patent uses metal foam as a composite material that combines the conductivity of metal with the compressibility of foam structure. This composite provides both the electrical properties of solid metal and the mechanical flexibility needed to adapt to circuit board irregularities, resolving the contradiction between strength and adaptability.
2Reliability
If solid metal posts are used, then electrical conductivity is improved, but the range of plastic deformation deteriorates
Solution Approach 1:
The metal foam structure provides a large range of plastic deformation through compression of the cellular structure. The interconnected metal struts in the foam can bend and deform significantly before failure, enabling the posts to accommodate thermal stresses and board irregularities while maintaining reliable electrical conductivity through the continuous metal pathway.
3Measurement precision
If specialized test sockets are used, then testing accuracy is improved, but device complexity and cost deteriorate
Solution Approach 1:
The flexible metal foam posts enable dynamic adjustment during testing, automatically adapting to contact pad positions on simple test boards. This eliminates the need for specialized rigid test sockets while maintaining testing accuracy, as the compliant posts can compensate for positioning variations and board irregularities during the testing process.
4Ease of manufacture
If rigid posts are used, then manufacturing simplicity is improved, but the need for specialized test equipment increases
Solution Approach 1:
The metal foam posts can be manufactured using conventional processes such as foam infiltration or direct foam formation, which are relatively simple and scalable. The material's ability to provide both compliance and conductivity eliminates the need for complex specialized test equipment, maintaining manufacturing simplicity while reducing test equipment requirements.
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 reliable contact with non-planar contact pads, reduces manufacturing costs, and enhances the flexibility and reliability of microelectronic packages by accommodating board warpage and thermal stresses through the use of metal foam posts with a high compressive plastic deformation range.
Implementation Method 1
provides a lower modulus of elasticity and allows for independent movement
Implementation Method 2
enhances the flexibility and reliability of microelectronic packages by accommodating board warpage and thermal stresses through the use of metal foam posts with a high compressive plastic deformation range
Implementation Method 3
high compressive plastic deformation range
Data Source
AI summary
A microelectronic component having a base and a plurality of conductive posts extending from said base. Each of the posts is formed from a connected lattice of metal having voids therein. The lattice may be formed by depositing metal onto a sacrificial element such as an open-celled polymeric foam. During use or during processing, the posts may be deformed , as by crushing the lattice.