Photosensitive Resin Composition for Semiconductor Package Substrates
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Solution Overview
Problem
Conventional photosensitive resin compositions fail to adequately meet the requirements for both crack resistance and High Accelerated Temperature and Humidity Stress (HAST) resistance, particularly in highly multi-layered semiconductor package substrates with ultrafine pitches, and lack sufficient low Coefficient of Thermal Expansion (CTE) and high glass transition temperature (Tg).
Innovation Solution
A photosensitive resin composition comprising an acid-modified bisphenol novolak type epoxy resin, a photopolymerizable monomer with a tricyclodecane structure and urethane bond, a photopolymerization initiator, and a silica filler with a maximum particle size of 1 μm or less, which is alkaline developable and suitable for forming a permanent resist with improved resolution and gold plating resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photosensitive resin compositions are used, then basic solder resist function is provided, but crack resistance and HAST resistance are insufficient for highly multi-layered substrates with ultrafine pitches
Solution Approach 1:
The patent uses a composite resin system combining acid-modified bisphenol novolak type epoxy resin with photopolymerizable monomers containing ethylenically unsaturated groups. This composite material approach creates a multi-functional resin composition that simultaneously achieves low CTE, high Tg, excellent crack resistance, and high resolution capability for ultrafine pitch applications.
Solution Approach 2:
The patent optimizes specific parameter ranges including CTE of 50 ppm/°C or less, Tg of 150°C or higher, and controlled molecular weight and acid value of the epoxy resin. These parameter changes enable the material to meet both reliability requirements (crack resistance) and manufacturing precision requirements (resolution) simultaneously.
2Strength
If low CTE and high Tg are achieved through resin modification, then crack resistance improves, but manufacturing complexity and formulation difficulty increase
Solution Approach 1:
The patent specifies precise parameter ranges for the acid-modified bisphenol novolak type epoxy resin including molecular weight, acid value, and CTE to achieve low CTE and high Tg. By controlling these parameters within defined ranges, the formulation process becomes more systematic and manageable despite the complexity of achieving multiple performance targets.
Solution Approach 2:
The patent combines acid-modified epoxy resin with photopolymerizable monomers and inorganic fillers to create a composite system where each component contributes specific properties. This composite approach simplifies the overall formulation strategy by dividing functionality across multiple components rather than requiring single-component solutions.
3Temperature
If silica filler is added to improve reflow resistance, then thermal stability improves, but particle size control becomes critical to maintain resolution
Solution Approach 1:
The patent specifies that silica filler particle size should be 1 μm or less to maintain excellent resolution while providing thermal stability and reflow resistance. This parameter control ensures that the filler particles do not interfere with the formation of fine patterns while still providing the necessary thermal performance.
Solution Approach 2:
The patent uses silica filler with controlled local particle size distribution to achieve different functions in different aspects: small particles (≤1 μm) provide thermal stability without compromising resolution, while the overall filler loading and distribution are optimized to maintain pattern fidelity in ultrafine pitch applications.
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 low CTE and high Tg, enhancing crack resistance and HAST resistance in multi-layered substrates with ultrafine pitches, while maintaining excellent resolution and gold plating resistance, making it suitable for high-reliability applications in semiconductor package substrates.
Implementation Method 1
a (c) component: a photopolymerization initiator
Data Source
AI summary
The present invention provides a photosensitive resin composition comprising an (a) component: an acid-modified epoxy resin, a (b) component: a photopolymerizable monomer having an ethylenically unsaturated group, a (c) component: a photopolymerization initiator, a (d) component: an epoxy resin, and an (e) component: an inorganic filler, wherein the (a) component comprises an acid-modified bisphenol novolak type epoxy resin and further the photosensitive resin composition satisfies a predetermined condition, and provides a photosensitive film, a permanent resist and a method for producing a permanent resist using the same.