Package Substrate with Step-Height Circuit Patterns
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Solution Overview
Problem
The existing package substrates face challenges in maintaining connection reliability at fine pitches due to the risk of short-circuits and increased manufacturing costs associated with tin plating, especially when assembling components with fine-pitch bumps.
Innovation Solution
A package substrate design featuring insulating layers with circuit patterns of varying heights, where pad areas are higher than pattern areas, and non-conductive paste is used to prevent short-circuits, eliminating the need for tin plating on pad areas, thus reducing the risk of defects and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tin plating is applied to prevent short-circuits during assembly, then connection reliability is improved, but manufacturing cost increases and pollution risk occurs
Solution Approach 1:
The patent extracts the tin plating process from the manufacturing flow by using a non-conductive paste that eliminates the need for tin plating on bump surfaces, thereby reducing manufacturing cost and pollution while maintaining connection reliability through the paste's insulating and bonding properties
Solution Approach 2:
The patent changes the electrical conductivity parameter of the bonding material from conductive (tin plating) to non-conductive (non-conductive paste), fundamentally altering the approach to preventing short-circuits while simplifying the manufacturing process
2Adaptability or versatility
If circuit patterns are configured at fine pitch to increase pad density, then substrate functionality is improved, but short-circuit risk between bumps increases
Solution Approach 1:
The non-conductive paste acts as an intermediary material between adjacent bumps, providing electrical insulation that prevents short-circuits while enabling fine-pitch configurations. The paste fills the spaces between closely spaced bumps, maintaining substrate functionality without compromising reliability
Solution Approach 2:
The non-conductive paste serves as a disposable insulating layer applied during assembly that prevents short-circuits in fine-pitch configurations without requiring permanent structural modifications or expensive plating processes
3Ease of manufacture
If non-conductive paste is used for bonding substrate and chip, then tin plating process is eliminated, but additional process steps are required
Solution Approach 1:
The non-conductive paste combines multiple functions into a single material: bonding, insulation, and short-circuit prevention. This merging of functions eliminates the separate tin plating process while providing comprehensive protection, actually reducing overall process complexity despite the paste application step
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 design enhances connection reliability by preventing short-circuits and voids, while minimizing the risk of defects and manufacturing costs by avoiding tin plating on pad areas, thereby improving the assembly process for fine-pitch circuit patterns.
Implementation Method 1
a non-conductive paste (NCP) interposed between the circuit patterns and pads of a die connected to the circuit patterns
Implementation Method 2
the pad areas and the pattern areas may form a step therebetween, such that the pad areas have a height higher than that of the pattern areas
Data Source
AI summary
A package substrate includes an insulating layer; and circuit patterns formed on the insulating layer and divided into pad areas and pattern areas that have different heights. In one aspect, there can be a non-conductive paste (NCP) interposed between the circuit patterns and pads of a die connected to the circuit patterns to fix the die onto the insulating layer.