Heat-Curable Epoxy Resin Composition for Optical Semiconductor Encapsulation
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Solution Overview
Problem
Conventional heat-curable epoxy resin compositions for optical semiconductor element encapsulation suffer from decreased strength and increased crack susceptibility due to the use of multifunctional or alicyclic epoxy resins, and the low glass-transition temperature of the epoxy resin can lead to issues during transfer molding, such as separation from lead frames in automotive applications.
Innovation Solution
A heat-curable epoxy resin composition is developed, comprising a triazine derivative epoxy resin, a bisphenol-type epoxy resin, an acid anhydride curing agent, and a flexibility imparting agent like polycaprolactone polyol or acrylic block copolymer, along with a curing accelerator, which maintains a favorable epoxy group to acid anhydride ratio and includes a phosphonium salt to enhance handling properties and crack resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multifunctional epoxy resin or alicyclic epoxy resin is used to improve heat resistance and light resistance, then transparency and thermal stability are improved, but strength decreases and crack resistance deteriorates
Solution Approach 1:
The patent uses a composite epoxy resin system combining triazine derivative epoxy resin (providing strength and crack resistance) with alicyclic epoxy resin (providing heat resistance and transparency). This composite approach allows both requirements to be met simultaneously by leveraging the complementary properties of different resin components.
2Strength
If flexibility imparting agent is added to improve crack resistance, then crack resistance improves, but glass-transition temperature decreases
Solution Approach 1:
The patent carefully controls the amount of flexibility imparting agent (polycaprolactone polyol or polycarbonate polyol) to be 1-10 parts by mass per 100 parts by mass of total epoxy resin. This parameter optimization ensures sufficient crack resistance while limiting the decrease in glass-transition temperature, achieving a balance between the two properties.
3Ease of operation
If low glass-transition temperature epoxy resin is used to improve handling property at room temperature, then ease of molding improves, but mechanical strength decreases and resin may be washed away or separated
Solution Approach 1:
The patent creates a composite system where triazine derivative epoxy resin (solid at room temperature, providing strength) is combined with alicyclic epoxy resin (lower melting point, providing ease of molding). The synergistic effect allows the resin to be moldable during processing while maintaining high mechanical strength in the final product.
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 composition achieves superior transparency, strength, and crack resistance at room temperature with minimal decrease in glass-transition temperature, enabling successful transfer molding and improved reliability of optical semiconductor devices.
Implementation Method 1
a heat-curable epoxy resin composition for optical semiconductor element encapsulation including a prepolymer obtained by a reaction of (A-1) being a triazine derivative epoxy resin having not less than 3 epoxy groups in one molecule, (A-2) being at least one epoxy resin selected from the group consisting of a bisphenol A-type epoxy resin, a bisphenol F-type epoxy resin, a hydrogenated bisphenol A-type epoxy resin and an alicyclic epoxy resin, (A-3) being an acid anhydride curing agent in liquid form at 50° C.
Implementation Method 2
a curing accelerator (B) comprised of an onium salt represented by the following formula (1): wherein X+ represents a cation selected from the group consisting of an aliphatic quaternary phosphonium ion, an aromatic quaternary phosphonium ion, an onium ion of 1,8-diaza-bicyclo[5.4.0]undeca-7-ene and an onium ion of an imidazole derivative
Implementation Method 3
the component (A-4) being a flexibility imparting agent selected from the group consisting of a polycaprolactone polyol, a polycarbonate polyol and an acrylic block copolymer
Data Source
AI summary
Provided are a heat-curable epoxy resin composition with a superior handling property, transparency and crack resistance; and an optical semiconductor device having an optical semiconductor element encapsulated by such composition. The composition includes:(A) a prepolymer obtained by a reaction of (A-1), (A-2), (A-3) and (A-4) at an epoxy group equivalent/acid anhydride group equivalent ratio of 0.6 to 2.0,(A-1) being a triazine derivative epoxy resin,(A-2) being at least one selected from the group consisting of a bisphenol A-type epoxy resin, a bisphenol F-type epoxy resin, a hydrogenated bisphenol A-type epoxy resin and an alicyclic epoxy resin,(A-3) being an acid anhydride curing agent as a liquid at 50° C., and(A-4) being a flexibility imparting agent selected from the group consisting of a polycaprolactone polyol, a polycarbonate polyol and an acrylic block copolymer; and(B) a curing accelerator comprised of an onium salt represented by:X+Y− (1)wherein X+ represents a cation, and Y− represents an anion.