Thermosetting Resin Composition for Printed Wiring Boards
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Solution Overview
Problem
Thermosetting resin compositions face issues with warpage, cracking, and inadequate thermal cycle characteristics, particularly when highly filled with inorganic fillers, leading to defects in printed wiring boards.
Innovation Solution
A thermosetting resin composition comprising an epoxy resin, a phenolic curing agent, spherical silicon dioxide or aluminum oxide, and a block copolymer with specific molecular weight and glass transition point characteristics is developed to enhance adhesion, reduce warpage, and improve thermal cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inorganic filler is highly filled to decrease CTE, then CTE matching with substrate is improved, but cracking occurs in the dry film in B-stage state
Solution Approach 1:
The patent applies parameter changes by carefully controlling the particle size distribution of inorganic fillers (combining fine particles of 0.1-10μm with coarse particles of 10-50μm), the glass transition temperature of the binder resin (50-150°C), and the molecular weight of the block copolymer (50,000-300,000). These parameter optimizations allow high filler content for CTE matching while preventing cracking through improved film flexibility and stress distribution.
Solution Approach 2:
The patent uses composite materials by combining epoxy resin with phenolic resin, adding block copolymer components, and incorporating dual-size inorganic filler systems. This composite approach creates a multi-phase material structure where each component contributes specific properties: epoxy provides adhesion, phenolic resin enhances thermal stability, block copolymer improves flexibility, and the dual-size filler system optimizes both CTE matching and crack resistance.
2Reliability
If a thermosetting resin composition is sufficiently cured, then adhesion and flexibility are improved, but warpage occurs due to shrinkage
Solution Approach 1:
The patent controls the glass transition temperature of the binder resin within 50-150°C and adjusts the curing characteristics of the thermosetting resin system. This parameter control allows the resin to achieve adequate adhesion and flexibility during curing while minimizing excessive shrinkage that causes warpage, by optimizing the crosslinking density and curing kinetics.
Solution Approach 2:
The patent applies local quality by using a dual-component resin system (epoxy + phenolic) with different curing rates and shrinkage characteristics in different regions of the material structure. The block copolymer also provides localized flexibility enhancement at the molecular level while maintaining overall structural integrity, allowing differential stress distribution that reduces warpage.
3Reliability
If the CTE of thermosetting resin is matched with substrate, then thermal cycle characteristics are improved, but cracking occurs in TCT when CTE difference is great
Solution Approach 1:
The patent optimizes the CTE of the cured film to be 50-80μm/m/°C by controlling the inorganic filler content (50-90 wt%) and particle size distribution. This parameter adjustment ensures CTE matching with common substrates like FR-4 and polyimide, preventing cracking during thermal cycle testing by minimizing differential thermal expansion stresses.
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 excellent low warp properties, suppressed cracking in the B-stage state, and improved thermal cycle characteristics, resulting in a cured product suitable for printed wiring boards with enhanced reliability and performance.
Implementation Method 1
it has become increasingly important that a block copolymer having both a rubbery phase and a glassy phase is used in order to suppress the occurrence of cracking
Implementation Method 2
when a difference between the coefficients of liner thermal expansion (CTE) of a thermosetting resin and a substrate or a substrate-forming material such as copper or an underfill is great, there is a problem that cracks are generated in the resist in TCT (thermal cycle test)
Implementation Method 3
a thermosetting resin composition comprising: (A) an epoxy resin; (B) a curing agent for an epoxy resin
Data Source
AI summary
Provided are: a thermosetting resin composition in which a cured product is excellent in low warp properties, thermal cycle characteristics, and the like, and occurrence of cracking of a coating film in a B-stage state is suppressed; a cured product thereof; and a printed wiring board in which the cured product is used. The thermosetting resin composition comprises: (A) an epoxy resin; (B) a curing agent for an epoxy resin; (C) spherical silicon dioxide and/or spherical aluminum oxide; and (D) a block copolymer.