Thermal-UV Curing Adhesive for Camera Module Lens Holder
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Solution Overview
Problem
Conventional thermal- and UV-curing adhesives used in camera module assembly peel off or lose thermal durability due to the mismatch in coefficient of thermal expansion between lens holders made of high CTE materials like polycarbonates and substrates.
Innovation Solution
A thermal- and UV-curing adhesive composition comprising urethane acrylate oligomers with a weight average molecular weight of 4,000 or more, acrylate monomers, particulate rubber, polyamine curing agents, and photopolymerization initiators, where the particulate rubber is present in at least 5% by weight, effectively addressing the thermal expansion mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional thermal- and UV-curing adhesive is used to adhere the lens holder to the substrate, then the lens holder and substrate are firmly adhered, but the adhesive peels off during heat-curing or loses thermal durability due to the big difference in coefficient of thermal expansion between the lens holder and the substrate
Solution Approach 1:
The invention changes the chemical composition parameters of the adhesive by incorporating specific rubber components (polybutadiene, styrene-butadiene rubber, or polyisoprene) in defined proportions (1-20 parts by weight per 100 parts of adhesive resin). This compositional parameter change enables the adhesive to achieve both strong bonding and thermal expansion compatibility between the lens holder and substrate, preventing peeling during heat-curing while maintaining thermal durability.
Solution Approach 2:
The invention creates a composite adhesive material combining adhesive resin with specific rubber components (polybutadiene, styrene-butadiene rubber, or polyisoprene). This composite structure provides both the bonding capability of the adhesive resin and the thermal expansion flexibility of the rubber, allowing the adhesive to accommodate CTE differences between dissimilar materials (lens holder and substrate) while maintaining both strength and thermal durability.
2Strength
If thermal-curing adhesive is used to adhere the lens holder to the substrate, then the lens holder and substrate are adhered together, but the distance between the lens and the image sensor changes during heat-curing
Solution Approach 1:
The invention modifies the adhesive's thermal and mechanical properties by incorporating rubber components that provide appropriate thermal expansion characteristics. This parameter change ensures that during heat-curing, the adhesive expands and contracts at a rate compatible with both the lens holder and substrate, preventing excessive dimensional changes that would affect the critical distance between the lens and image sensor, thereby maintaining manufacturing precision.
Solution Approach 2:
The invention addresses thermal expansion by selecting rubber components (polybutadiene, styrene-butadiene rubber, or polyisoprene) that provide suitable thermal expansion properties. These rubber additives modify the adhesive's overall thermal expansion coefficient to be compatible with the lens holder and substrate, reducing dimensional instability during thermal curing and ensuring precise maintenance of the optical distance.
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 adhesive composition significantly reduces peeling during heat-curing and enhances thermal durability, ensuring precise distance maintenance between the lens and image sensor in camera modules.
Implementation Method 1
at least one photopolymerization initiator
Implementation Method 2
at least one polyamine curing agent having a primary amine and/or a secondary amine
Implementation Method 3
heat-curing
Data Source
AI summary
Provided is an adhesive that is resistant to peeling off during heat-curing when a lens holder is adhered to a substrate having an image sensor fixed thereon in assembling a camera module, and that has excellent thermal durability after being cured. A thermal- and UV-curing adhesive composition contains (a) at least one urethane acrylate oligomer containing at least one polycarbonate-based urethane acrylate oligomer, (b) at least one acrylate monomer, (c) at least one particulate rubber, (d) at least one polyamine curing agent having a primary amine and/or a secondary amine, and (e) at least one photopolymerization initiator, wherein the at least one urethane acrylate oligomer (a) has a weight average molecular weight of 4,000 or more, and the at least one particulate rubber (c) is present in an amount of 5% by weight or more in the entire composition.