Carbon-Based Anisotropic Conductive Film for Fine-Pitch Die Interconnects
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Solution Overview
Problem
Conventional methods for forming electrical and mechanical connections between semiconductor dice with high density and small critical dimensions are complex, time-consuming, and require precise alignment, limiting the minimum vertical standoff distance and being pitch-and-pillar limited due to conductivity limitations.
Innovation Solution
Anisotropic conductive films with discrete, laterally-spaced regions of carbon-based material are used, which exhibit low electrical resistivity and are formed on a substrate before the adhesive dielectric material, allowing for thin, compact semiconductor device assemblies with improved electrical connectivity without the need for precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods with conductive pillars and underfill materials are used, then electrical and mechanical connections are established, but the process becomes complex and time-consuming
Solution Approach 1:
The patent removes conductive pillars and underfill materials from the conventional stacking process, replacing them with anisotropic conductive film that provides both electrical connection and mechanical bonding in a single component, thereby simplifying the fabrication process while maintaining connection reliability
Solution Approach 2:
The anisotropic conductive film serves multiple functions simultaneously: it provides electrical conductivity through conductive particles, mechanical adhesion through adhesive material, and structural support, eliminating the need for separate conductive pillars and underfill materials
2Manufacturing precision
If conventional alignment methods are used, then precise alignment is achieved, but the minimum vertical standoff distance is limited
Solution Approach 1:
The patent segments the conductive material into discrete conductive particles within the anisotropic film, which can be compressed to make contact with bonding pads, allowing for precise electrical connection without requiring precise alignment of entire conductive structures, thereby enabling smaller vertical standoff distances
3Reliability
If conventional conductive materials are used, then electrical conductivity is achieved, but pitch and pillar limitations occur
Solution Approach 1:
The patent changes the physical state and distribution of conductive material from solid conductive pillars to discrete conductive particles within a compressed film, allowing the particles to deform and conform to bonding pad surfaces, thereby enabling finer pitch spacing and greater flexibility in design
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 carbon-based anisotropic conductive films enable efficient electrical and mechanical connections between semiconductor dice, eliminating the need for conductive pillars and underfill materials, allowing for finer-pitched conductive elements and faster fabrication while maintaining electrical conductivity.
Implementation Method 1
The carbon-based material may exhibit extremely low electrical resistivity, enabling the ACF to effectively electrically connect conductive elements of adjoining dice
Implementation Method 2
The ACF may also be formed with adhesive dielectric material on opposing sides of the ACF
Data Source
AI summary
An anisotropic conductive film (ACF) is formed with an ordered array of discrete regions that include a conductive carbon-based material. The discrete regions, which may be formed at small pitch, are embedded in at least one adhesive dielectric material. The ACF may be used to mechanically and electrically interconnect conductive elements of initially-separate semiconductor dice in semiconductor device assemblies. Methods of forming the ACF include forming a precursor structure with the conductive carbon-based material and then joining the precursor structure to a separately-formed structure that includes adhesive dielectric material to be included in the ACF. Sacrificial materials of the precursor structure may be removed and additional adhesive dielectric material formed to embed the discrete regions with the conductive carbon-based material in the adhesive dielectric material of the ACF.