Epoxy Silane Adhesive for Image Sensor Packaging
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Solution Overview
Problem
Conventional adhesive compositions for bonding protective glass with silicon substrates in image sensors, such as CCD and CMOS, face issues with adhesive properties, hermetic sealing, hygroscopicity, heat resistance, light resistance, and warpage after back-side polishing, particularly in three-dimensional packaging, leading to high costs and low productivity.
Innovation Solution
An epoxy-containing high-molecular silane compound with specific molecular weight and structural units, combined with a solvent, acid anhydride, antioxidant, and crosslinking agents, forms an adhesive composition that eliminates the need for exposure and baking steps, providing strong adhesive and hermetic sealing while enhancing heat and light resistance and reducing substrate warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If photosensitive resin composition is used for bonding protective glass with silicon substrate, then adhesive properties can be achieved, but the process requires exposure, baking and development steps resulting in high cost and low productivity
Solution Approach 1:
The patent extracts and eliminates the photolithographic processing steps (exposure, baking, development) from the adhesive bonding process by using a heat-curable adhesive composition instead of photosensitive resin, thereby simplifying the manufacturing process and improving productivity while maintaining adhesive performance
Solution Approach 2:
The patent changes the curing mechanism parameter from photopolymerization to thermal curing, allowing the adhesive to be applied directly without photolithographic steps. The adhesive composition contains epoxy resin and curable compounds that react upon heating, eliminating the need for exposure and development steps
2Strength
If conventional photosensitive resin composition is used, then bonding can be achieved, but hermetic sealing properties and hygroscopicity are insufficient after heat curing
Solution Approach 1:
The patent employs a composite adhesive composition containing multiple components including epoxy resin, polyimide resin, curable compounds, and silane coupling agents. This composite formulation provides both strong bonding capability and excellent hermetic sealing properties, as well as improved resistance to moisture and chemicals
Solution Approach 2:
The patent introduces specific functional components at controlled concentrations to provide localized properties: silane coupling agents enhance hermetic sealing and moisture resistance, while polyimide resin provides thermal stability and chemical resistance, creating a multi-functional adhesive layer
3Ease of manufacture
If heat-curable adhesive containing polyimide resin is used, then simple curing process is achieved, but adhesive properties, heat resistance and light resistance are insufficient
Solution Approach 1:
The patent combines polyimide resin with epoxy resin and curable compounds to create a composite adhesive system that maintains the simple heat-curing process while significantly improving adhesive properties, heat resistance, and light resistance through synergistic interactions between components
Solution Approach 2:
The patent optimizes the molecular weight and structural parameters of the polyimide resin and epoxy components, along with their ratio and concentration, to achieve optimal balance between ease of processing and performance characteristics including adhesive strength, heat resistance, and light resistance
4Strength
If conventional adhesive is used for three-dimensional packaging with back-side polishing, then bonding is achieved, but significant warpage occurs after polishing
Solution Approach 1:
The patent adjusts the thermal and mechanical parameters of the adhesive composition, including glass transition temperature, modulus, and thermal expansion coefficient, to match the substrate materials. This parameter optimization minimizes differential stress during back-side polishing and reduces substrate warpage while maintaining strong bonding
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 enables low-cost, high-productivity packaging with improved adhesive and sealing properties, high heat and light resistance, and reduced warpage, making it suitable for three-dimensional packaging of image sensors.
Implementation Method 1
an adhesive composition comprising an epoxy-containing high-molecular silane compound
Implementation Method 2
after heat curing
Data Source
AI summary
An adhesive composition useful in bonding a protective glass with a silicon substrate of a semiconductor device contains (A) an epoxy-containing high-molecular compound and (B) a solvent. The compound (A) has a weight average molecular weight of 3,000 to 500,000 and repeating units represented by the following formula (1):wherein R1 to R4 each represent a monovalent hydrocarbon group, m is 1 to 100, a, b, c and d indicate ratios of respective repeating units based on a number of all repeating units and each stand for 0 or a positive number with a proviso that c and d are not 0 at the same time and 0<(c+d)/(a+b+c+d)≦1.0 is satisfied, and X and Y are phenolic hydroxyl-containing, divalent aromatic groups.