Transfer Molding Die with Recess Site for Multi-Scale Optical Features
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Solution Overview
Problem
Conventional transfer molding devices can only create fine submicron recess and projection patterns on the outer surface of resin films and are unable to simultaneously produce submillimeter structures.
Innovation Solution
A transfer molding method involving a die structure with a recess site on one of the dies allows for the transfer of a pattern onto a resin sheet while forming a thick portion that protrudes greater than the maximum height of the recesses and projections, by heating and compressing the resin sheet between the dies, allowing the resin to flow into the recess site and form a thick portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional transfer molding is used to create fine submicron recess and projection patterns on the resin film surface, then the surface pattern transfer is achieved, but submillimeter structures cannot be simultaneously created
Solution Approach 1:
The die surface is segmented into two distinct functional zones: a transfer surface with submicron recesses and projections for fine surface patterning, and a separate recess site with submillimeter dimensions for creating thick portions. This segmentation allows each zone to independently perform its specific function without interfering with the other, enabling simultaneous creation of both fine surface patterns and large-scale structures in a single molding process
Solution Approach 2:
Different regions of the die are assigned different local qualities and functions: the transfer surface region is designed with submicron-scale features for optical surface patterning, while the recess site region is designed with submillimeter-scale cavities for creating thick portions. This local differentiation of quality and function allows the single die to produce multi-scale structures with appropriate characteristics for each scale
2Manufacturing precision
If the resin sheet is heated and compressed to transfer the pattern, then the transfer surface is transferred to the resin sheet, but thick portions greater than the maximum height of recesses and projections cannot be formed
Solution Approach 1:
The die cavity is segmented into a transfer surface area that contacts the resin sheet for pattern transfer, and a recess site area with greater depth that receives melted resin to form thick portions. This spatial segmentation allows the pattern transfer function and thick portion formation function to occur simultaneously in different locations without conflict
Solution Approach 2:
The recess site extends in the depth dimension beyond the maximum height of the transfer surface features, creating a third dimensional space for thick portion formation. While the transfer surface operates at submicron heights, the recess site provides submillimeter depth, adding a dimensional layer that enables thick portion creation without compromising surface pattern transfer
3Manufacturing precision
If multiple separate processes are used to create fine patterns and thick portions, then each feature type can be created, but the process complexity and time increase
Solution Approach 1:
The die integrates multiple functions into a single component: pattern transfer capability, thick portion formation capability, and resin flow guidance features. By merging these functions into one die structure, the process complexity is reduced compared to using separate tools or multiple molding steps, while maintaining the ability to create both fine patterns and thick portions simultaneously
Solution Approach 2:
The die is designed as a universal tool that performs multiple functions: transferring submicron surface patterns, creating submillimeter thick portions, and controlling resin flow distribution. This multi-functionality eliminates the need for separate specialized tools for each feature type, simplifying the overall manufacturing process
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 method enables the simultaneous creation of submicron and submillimeter features on the resin sheet, reducing internal stresses and ensuring uniformity, which improves light guidance and illumination efficiency in optical elements like light guide plates.
Implementation Method 1
the resin sheet may be heated to no less than the glass transition temperature during the transfer molding step
Implementation Method 2
the resin sheet may be melted and flowed towards the recess site formed in the transfer surface in the transfer molding step
Implementation Method 3
bringing the first and second dies near a position that reduces the thickness of portions on the molded resin sheet other than the thick portion to less than the initial thickness thereof
Data Source
AI summary
A die structure has a first die, a second die that comes in contact with and separate from the first die, a heating unit provided in at least one of the first and second dies, and a transfer member provided in at least one of the first and second dies that brings a resin sheet supplied between the first and second dies into contact with a transfer surface and carrying out transfer molding, and a recess site formed on the transfer member near the transfer surface.