X-Ray Activated Adhesive Composition for Hidden Joint Curing
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Solution Overview
Problem
Conventional photoinitiators require direct line-of-sight access to a light source for curing, limiting their use in multilayer stacks and processes with thermal expansion mismatches, and they generate heat during curing.
Innovation Solution
A curable adhesive composition comprising a polymerizable monomer, a photoinitiator responsive to a selected wavelength of light, and an energy converting material that emits this wavelength upon exposure to radiation, allowing curing without direct light access and minimizing thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional photoinitiators are used for adhesive curing, then curing can be achieved at ambient temperatures, but direct line-of-sight access to light source is required which limits use in multilayer stacks
Solution Approach 1:
The patent introduces an intermediary substance (phosphor material) that converts X-ray energy into UV light. This mediator enables curing in locations where direct UV light access is impossible, such as internal structures of multilayer stacks, by transforming the activation mechanism from direct optical to indirect radiative conversion.
Solution Approach 2:
The patent replaces the conventional UV light-based photopolymerization system with an X-ray activated system. This substitution eliminates the line-of-sight requirement by using penetrating X-ray radiation that can activate phosphors throughout the adhesive volume, enabling curing in previously inaccessible geometries.
2Manufacturing precision
If conventional UV curing is used, then curing proceeds from outside surface to inside, but this creates skin formation and depth limitations
Solution Approach 1:
The patent transitions from surface-based UV curing to volumetric X-ray activation. By using penetrating X-ray radiation that activates phosphors distributed throughout the adhesive bead volume, curing occurs simultaneously throughout the entire depth rather than progressing from surface to center, eliminating skin formation and enabling uniform curing of deep adhesive structures.
3Stability of the object's composition
If thermoset adhesives are cured by heating, then polymerization occurs, but thermal expansion mismatch causes stress in electronic components
Solution Approach 1:
The patent replaces thermal curing with radiation-based photopolymerization. By using X-ray activated phosphors to initiate curing at or near ambient temperatures, the process eliminates thermal expansion mismatches between dissimilar materials while achieving complete polymerization through the photoinitiation mechanism.
4Temperature
If UV light is used for curing, then ambient temperature polymerization occurs, but heat is generated during the curing process
Solution Approach 1:
The patent changes the energy activation parameter from optical (UV) to ionizing radiation (X-ray). This parameter change enables photopolymerization to proceed at ambient or controlled low temperatures by using high-energy X-rays that activate phosphors without generating significant heat, thereby eliminating thermal damage risks to temperature-sensitive electronic components.
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
Enables adhesive curing within internal structures and at ambient temperatures, overcoming depth limitations and thermal expansion mismatches, providing selective and controlled curing geometries.
Implementation Method 1
at least one photoinitiator, which, when exposed to UV light, releases chemical energy to form free radicals or cations to initiate the reaction of the monomers
Implementation Method 2
at least one phosphor capable of producing light when exposed to radiation (typically X-rays)
Data Source
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AI summary
A curable resin or adhesive composition includes at least one monomer, a photomitiator capable of initiating polymerization of the monomer when exposed to light, and at least one energy converting material, preferably a phosphor, capable of producing light when exposed to radiation (typically X-rays). The material is particularly suitable for bonding components at ambient temperature in situations where the bond joint is not accessible to an external light source. An associated method includes: placing a polymerizable adhesive composition, including a photoinitiator and energy converting material, such as a down-converting phosphor, in contact with at least two components to be bonded to form an assembly: and, irradiating the assembly with radiation at a first wavelength, capable of conversion (down-conversion by the phosphor) to a second wavelength capable of activating the photoinitiator, to prepare items such as inkjet cartridges, wafer-to-wafer assemblies, semiconductors, integrated circuits, and the like.