UV Curable Resin Layer Prepregs for PCB Component Encapsulation
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Solution Overview
Problem
Existing prepreg layers in printed circuit board manufacturing are often insufficient in resin thickness, failing to adequately encapsulate electronic components during lamination, which can lead to damage from pressure and temperature.
Innovation Solution
A prepreg comprising a UV curable resin layer positioned between two thermally curable resin layers, which are at least partially cured, allowing for improved encapsulation of electronic components through the use of a mask layer to control UV curing and ensure sufficient resin flow during lamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a thin prepreg layer is used adjacent to electronic components, then the laminate thickness is reduced, but the resin is insufficient to fill windows and encapsulate components during lamination
Solution Approach 1:
The prepreg is segmented into multiple resin layers with different functions: a first thermally curable resin layer (5-40 μm) for initial bonding, a UV curable resin layer (10-500 μm) for component encapsulation, and a second thermally curable resin layer (5-40 μm) for final bonding. This segmentation allows each layer to be optimized for its specific purpose, resolving the contradiction between thin overall thickness and sufficient encapsulation resin.
Solution Approach 2:
The UV curable resin layer is positioned locally adjacent to electronic components where encapsulation is needed, while other areas use thinner thermally curable resin layers. This local quality approach ensures sufficient resin thickness (10-500 μm) exactly where components require protection, while maintaining overall thin laminate dimensions in non-critical areas.
2Reliability
If a thick prepreg layer is used to ensure sufficient resin for encapsulation, then component protection is improved, but the laminate thickness increases
Solution Approach 1:
The thick resin requirement is segmented into a UV curable layer (10-500 μm) positioned only where components need encapsulation, flanked by thin thermally curable layers (5-40 μm each). This segmentation provides sufficient total resin thickness for protection while keeping the overall laminate thin in areas without components.
Solution Approach 2:
The resin structure transitions from a single thick layer to a multi-layer configuration with vertical differentiation: thin thermally curable layers for bonding at the extremes, and a thicker UV curable layer in the middle for encapsulation. This dimensional reorganization optimizes both protection and thickness.
3Reliability
If a UV curable resin layer is added between thermally curable resin layers, then encapsulation capability is improved, but the prepreg structure complexity increases
Solution Approach 1:
The prepreg is divided into three distinct resin layers with different curing mechanisms, where the UV curable layer is sandwiched between two thermally curable layers. This segmentation enables the UV layer to be activated independently through photomasks, providing precise encapsulation control without requiring complex processing equipment.
Solution Approach 2:
The UV curable resin layer acts as an intermediary between the two thermally curable resin layers, providing a bridge that enables selective encapsulation of components. The UV layer can be cured through photomasks to create windows for component placement, while the thermally curable layers provide the bonding function, simplifying the overall process.
4Manufacturing precision
If photomasks are used to control UV curing, then resin flow control is improved, but the manufacturing process complexity increases
Solution Approach 1:
Photomasks serve as intermediaries that selectively transmit or block UV light to control which portions of the UV curable resin layer are cured. This allows precise definition of encapsulation zones and windows for component placement, achieving high manufacturing precision through a relatively simple tool.
Solution Approach 2:
The curing process uses parameter changes in the UV light exposure: photomasks control the spatial distribution of UV energy, and exposure time/dose controls the degree of curing. This enables precise control of resin flow and encapsulation boundaries without complex mechanical or chemical systems.
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 described prepreg solution effectively encapsulates electronic components by ensuring a sufficient amount of resin flows around and fills gaps, protecting the components from lamination pressures and temperatures.
Implementation Method 1
directing UV light at the UV mask layer for a time sufficient to cure the UV curable resin layer below the UV light transparent portion of the prepreg
Implementation Method 2
subjecting the stack to laminating conditions including temperatures and pressures sufficient to cause the UV light curable resin layer portion and the partially cured thermally curable resin of the first thermally curable resin layers become liquid, flow around the electrical component
Data Source
AI summary
Prepregs having a UV curable resin layer located adjacent to a first thermally curable resin layer or sandwiched between first and second thermally curable resin layers wherein the UV curable resin layer is uncured or partially cured as well as methods for preparing laminates using the prepregs wherein the laminate includes at least one UV curable resin encapsulated electrical component.