Capacitive Substrate Assembly with Spacer-Based Distance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing substrate assemblies with capacitive interconnections face challenges in achieving precise and repeatable distance control between conductive pads, leading to inefficiencies and increased area usage due to non-uniformity in bump and recess formation, which complicates manufacturing and increases costs.
Innovation Solution
A substrate assembly with capacitive interconnections featuring conductive coupling elements that are ohmically coupled to electrical-interconnection elements and capacitively coupled to pads via a dielectric layer, allowing for precise alignment and reduced area usage by utilizing bumps or pillar bumps for both mechanical support and electrical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If recesses and bumps are used to control distance between conductive pads, then distance control is achieved, but manufacturing precision deteriorates due to non-uniformity in bump and recess formation
Solution Approach 1:
The patent extracts the distance control function from the complex interaction of recesses and bumps by introducing a dedicated spacer element. This spacer is formed as a separate structure (e.g., via electroplating on a sacrificial layer) that defines the gap distance independently of bump formation variations, thereby resolving the contradiction between distance control and manufacturing uniformity
Solution Approach 2:
The spacer acts as an intermediary element between the first and second substrates, mediating the distance control function. Instead of relying on precise coordination between recesses and bumps, the spacer provides a stable reference distance that is insensitive to variations in bump or recess dimensions, thus improving both distance control and manufacturing reliability
2Stability of the object's composition
If numerous bumps are formed for mechanical support, then mechanical stability is improved, but area usage increases and manufacturing complexity increases
Solution Approach 1:
The patent segments the functions of bumps into two distinct groups: a first plurality of bumps dedicated to capacitive coupling (information transfer) and a second plurality of bumps dedicated to mechanical support. This segmentation allows the support bumps to be strategically positioned for optimal mechanical stability with minimal area usage, while the coupling bumps are positioned for electrical function, thereby resolving the contradiction between mechanical stability and area efficiency
Solution Approach 2:
The spacer element serves multiple functions simultaneously: it defines the capacitive gap distance, provides mechanical support, and enables alignment between substrates. By making the spacer multi-functional, the patent reduces the need for separate support structures, thereby decreasing area usage and manufacturing complexity while maintaining mechanical stability
3Adaptability or versatility
If recesses are formed in substrates for bump placement, then capacitive coupling is enabled, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the spacer formation process with the bump formation process by using the same electroplating technique for both. The spacer is formed on a sacrificial layer that is subsequently removed, leaving the spacer in place. This merging of processes reduces device complexity and manufacturing cost compared to forming recesses separately, while still enabling precise capacitive coupling
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 enables efficient capacitive data transfer while minimizing substrate area usage, simplifying the manufacturing process, and reducing costs by integrating mechanical support and electrical coupling functions into the same elements, thus enhancing the performance and stability of the substrate assembly.
Implementation Method 1
a first coupling element of conductive material, extending between the first electrical-interconnection element and the third electrical-interconnection element... the first coupling element being ohmically coupled to the first electrical-interconnection element and capacitively coupled to the third electrical-interconnection element
Data Source
AI summary
An assembly including: a first substrate having a first surface and housing a first electrical-interconnection element and a second electrical-interconnection element in a position corresponding to the first surface; a second substrate having a second surface, housing a third electrical-interconnection element and a fourth electrical-interconnection element in a position corresponding to the second surface, and provided with a dielectric layer extending on top of the third interconnection element; and a first bump and a second bump made of conductive material, extending between the first electrical-interconnection element and the third electrical-interconnection element and, respectively, between the second electrical-interconnection element and the fourth electrical-interconnection element, at least partially aligned to the respective electrical-interconnection elements, the first bump being ohmically coupled to the first interconnection element and capacitively coupled to the third interconnection element, and the second bump being ohmically coupled to the second interconnection element and to the fourth interconnection element.