Package Substrate Conductive Pillars for Thinner Fine-Pitch Routing
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Solution Overview
Problem
Conventional package substrates face challenges in achieving thinness, high wiring density, and cost-effective fabrication due to the need for thick insulating layers, wide external pads, and expensive laser drilling methods.
Innovation Solution
The use of conductive pillars as external contacts, with a seeding layer around their periphery and bottom, eliminates the need for a wiring layer on the insulating layer, allowing for thinner substrates and finer line widths/pitches, and replaces laser drilling with cost-effective exposure and development methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wiring layer is made on the insulating layer to serve as external contacts, then the insulating layer needs to have a certain thickness, but the thickness of the package substrate becomes difficult to thin
Solution Approach 1:
The patent extracts the wiring layer from the insulating layer structure. Instead of forming external contacts on the insulating layer surface, conductive pillars are formed directly on the circuit layer, eliminating the need for a thick insulating layer with wiring, thus reducing substrate thickness while maintaining external contact functionality
Solution Approach 2:
The patent inverts the conventional structure by placing conductive pillars directly on the circuit layer rather than forming wiring on the insulating layer. This inversion allows the insulating layer to be thinner since it no longer needs to support wiring structures, achieving both external contact functionality and reduced thickness
2Reliability
If external pads are made wider to meet circuit specifications, then external contact reliability is improved, but the wiring density of the package substrate is limited
Solution Approach 1:
The patent changes the geometric parameters of external contacts by using narrow conductive pillars instead of wide external pads. The conductive pillars have smaller cross-sectional areas, allowing closer spacing and higher wiring density while maintaining reliable electrical connections through direct contact with the circuit layer
3Manufacturing precision
If laser drilling method is used to form openings in the insulating layer, then precise opening formation is achieved, but the fabricating cost increases
Solution Approach 1:
The patent removes the insulating layer opening formation step entirely from the manufacturing process. By forming conductive pillars directly on the circuit layer surface, the need for laser drilling openings through the insulating layer is eliminated, reducing fabrication cost while maintaining precise conductive pillar formation
Solution Approach 2:
The patent replaces the laser drilling process with a direct deposition or formation process for conductive pillars. Instead of using expensive laser equipment to drill openings, the conductive pillars are formed directly on the circuit layer, substituting a costly mechanical/optical process with a more cost-effective manufacturing approach
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 solution results in thinner, higher-density wiring substrates with reduced fabrication costs, enabling fine line width and pitch specifications and improved bonding properties.
Implementation Method 1
a copper electroplating process is performed on the metal layer 120 so as to form a wiring layer 13
Data Source
AI summary
A package substrate is provided, in which conductive pillars are formed on a circuit layer of a core board body, and an insulating layer encapsulates the conductive pillars in such a manner that the conductive pillars are exposed from a surface of the insulating layer for use as external contacts. Hence, there is no need to fabricate a wiring layer on the insulating layer. Consequently, a thickness of the package substrate is smaller to meet the requirements of thinning.