Double-Sided Flexible Wiring Board for Thin IC Substrates
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Solution Overview
Problem
Current methods for manufacturing IC substrates either result in thick substrates with warping issues due to lack of rigidity or thinner substrates prone to wrapping and scraping, limiting their usability in semiconductor packaging.
Innovation Solution
A method involving a roll-to-roll process using a double-sided flexible copper clad laminate with blind vias and conductive fillings, followed by lamination with rigid insulating layers and additional wiring layers, allowing for the creation of thinner IC substrates with improved mechanical strength and reduced warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a copper clad laminate is used as a core, then the IC substrate has rigid support, but the thickness becomes too large (100 micrometers)
Solution Approach 1:
The patent removes the traditional copper clad laminate core and replaces it with a flexible substrate core. This extraction of the rigid core component allows the substrate to achieve the necessary mechanical strength through alternative means (flexible substrate with adhesive and copper foil layers) while significantly reducing the overall thickness from 100 micrometers to a thinner configuration suitable for semiconductor packaging.
Solution Approach 2:
The patent creates a composite structure consisting of a flexible substrate core, adhesive sheet, and copper foil layers. This composite material approach replaces the traditional homogeneous copper clad laminate core, achieving both thickness reduction and adequate mechanical support through the synergistic combination of different materials with complementary properties.
2Length of stationary object
If a single-sided build up method is used, then the thickness of IC substrate is reduced, but the IC substrate wrap occurs and multiple IC substrates are scraped
Solution Approach 1:
The patent inverts the traditional single-sided build-up approach by implementing a double-sided build-up method. Instead of building wiring layers from only one side of the substrate, the invention applies adhesive sheets and copper foil layers to both sides of the flexible substrate core. This inversion provides mechanical balance and structural stability that prevents warping and wrap issues, thereby improving reliability while maintaining reduced thickness.
Solution Approach 2:
The patent changes the process parameter from single-sided to double-sided build-up construction. This parameter change fundamentally alters the structural development process, enabling simultaneous formation of wiring layers on both sides of the substrate, which balances mechanical stresses and prevents warping during manufacturing and subsequent processing.
3Strength
If the core thickness is increased to 100 micrometers, then the IC substrate has sufficient rigidity, but it becomes impossible to make the IC substrate thinner for semiconductor package
Solution Approach 1:
The patent fundamentally changes the material parameter from rigid copper clad laminate to flexible substrate. This parameter change enables the substrate thickness to be optimized for semiconductor packaging applications (thinner configuration) while the necessary rigidity is provided by the flexible substrate material itself and the composite structure, rather than by increasing core thickness.
Solution Approach 2:
The patent employs a flexible substrate core instead of a rigid copper clad laminate core. This flexible shell approach allows the substrate to be made thinner while maintaining sufficient mechanical strength through the flexibility of the substrate material and the reinforcing effect of the adhesive and copper foil layers, thereby achieving both thickness reduction and adequate rigidity.
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 the production of thinner IC substrates with enhanced mechanical strength and reduced warping, facilitating their use in semiconductor packaging while maintaining efficient manufacturing processes.
Implementation Method 1
laminating a adhesive sheet and a copper foil onto the core to build the core up
Implementation Method 2
laminating a adhesive sheet and a copper foil onto the core
Implementation Method 3
plating through hole
Data Source
AI summary
A method for manufacturing an IC substrate includes following steps: providing a roll of double-sided flexible copper clad laminate; converting the roll of double sided flexible copper clad laminate into a roll of double sided flexible wiring board in a roll to roll manner; cutting the roll of double-sided flexible wiring board into a plurality of separate sheets of double sided flexible wiring board; forming first and second rigid insulating layers on the first and second wiring layers of each sheet of double sided flexible wiring board; forming third and fourth wiring layers on the first and second rigid insulating layers, and electrically connecting the first and third wiring layers, and electrically connecting the fourth and second wiring layers, thereby obtaining a sheet of substrate having a plurality of IC substrate units; and cutting the sheet of substrate into separate IC substrate units.