Tapered Stacked Via Posts in Multilayer Electronic Structures
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Solution Overview
Problem
Current interconnect technologies, such as drill & fill, face limitations in fabricating high-density, high-reliability vias with varying sizes and shapes due to laser drilling's tapering and rough sidewalls, leading to reliability issues and increased costs, especially in composite dielectric materials.
Innovation Solution
The use of pattern or panel plating technologies to deposit copper via posts in a photo-resist, followed by lamination with a dielectric material, allows for the creation of multilayer electronic support structures with stacked via posts of different dimensions, enabling flexible via shapes and sizes within the same layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser drilling is used to create vias, then via channels can be formed through dielectric material, but the via sides walls become rough and taper inwards
Solution Approach 1:
The patent replaces the mechanical laser drilling process with an electrochemical etching process using ferric chloride solution. This chemical etching method produces smooth, parallel sidewalls without the tapering and roughness inherent in laser drilling, thereby resolving the contradiction between ease of manufacture and manufacturing precision.
Solution Approach 2:
The patent changes the fundamental parameter of via formation from mechanical ablation (laser) to chemical dissolution (electrochemical etching). This parameter change fundamentally alters the sidewall characteristics, producing smooth, uniform walls that maintain constant diameter throughout the via length, thus resolving the sidewall quality issue.
2Reliability
If drill & fill technology is used to create vias, then electrical connections can be established, but the throughput rate is limited and fabrication costs become prohibitive
Solution Approach 1:
The patent merges the via formation and metal deposition steps into a single integrated process. By electrochemically etching copper directly from a copper-clad laminate, the via channels are formed and simultaneously filled with copper material, eliminating the separate drill and fill operations. This integration dramatically increases throughput while maintaining reliable electrical connections.
Solution Approach 2:
The patent enables continuous via formation and filling in a single uninterrupted electrochemical process. The ferric chloride solution continuously etches the copper while the via channels are simultaneously filled, creating a continuous useful action rather than discrete steps, thereby improving productivity without sacrificing connection reliability.
3Adaptability or versatility
If different sized via channels are drilled and filled, then various via sizes can be achieved, but the via channels fill at different rates causing dimpling or overfill
Solution Approach 1:
The patent applies local quality by allowing different regions of the copper-clad laminate to be etched at different rates based on local via size requirements. The electrochemical etching process naturally adapts to local conditions, with larger vias being etched more rapidly than smaller ones, ensuring all vias fill uniformly to their respective appropriate levels without dimpling or overfill.
4Ease of manufacture
If laser drilling is used on composite dielectric materials, then via channels can be created, but the minimum via diameter is limited to about 60 microns with significant tapering
Solution Approach 1:
The patent replaces mechanical laser drilling with electrochemical etching using ferric chloride. This substitution eliminates the minimum diameter limitation and tapering inherent in laser drilling, allowing precise control of via dimensions including smaller diameters and uniform cylindrical shapes throughout the via length.
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 approach enables cost-effective fabrication of a wide range of via shapes and sizes, reducing tapering and roughness issues, and allows for efficient electrical connections while minimizing manufacturing costs and improving reliability.
Implementation Method 1
The via channels are etched therein using a ferric chloride solution
Implementation Method 2
The via channels are then filled with a plating material, usually copper
Data Source
AI summary
A multilayer electronic support structure comprising a plurality of layers extending in an X-Y plane consisting of a dielectric material surrounding metal via posts that conduct in a Z direction perpendicular to the X-Y plane, wherein a stacked via structure crossing at least two via layers of the plurality of layers comprises at least two via posts in neighboring via layers wherein the at least two stacked via posts in neighboring layers have different dimensions in the X-Y plane, such that the stacked via structure tapers.