TSV Mold Underfill Epoxy Composition for Heat Dissipation Reliability
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Solution Overview
Problem
Semiconductor devices with high wiring density face issues with heat dissipation due to short distances between chips and wafer, leading to performance degradation. Additionally, the use of mold underfill materials with silica fillers of low thermal conductivity exacerbates this problem, and the presence of high ionic impurities, such as chloride ions, can cause short-circuiting in biased HAST tests.
Innovation Solution
A liquid epoxy resin composition is developed for use as a mold underfill material for TSV, comprising an epoxy resin, a curing agent, a combination of silica and alumina fillers, and carbon black. The composition includes an aliphatic epoxy resin, a nitrogen-containing heterocyclic curing agent, and an ion trapping agent to manage chloride ion content, resulting in a cured product with enhanced thermal conductivity and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silica fillers are used in mold underfill material, then the strength and coefficient of thermal expansion are improved, but the thermal conductivity remains low
Solution Approach 1:
The patent uses a composite filler system combining silica particles (5-50 nm) with alumina particles (0.1-10 μm) in specific weight ratios. This composite approach allows the silica to provide strength and CTE matching while the alumina contributes high thermal conductivity, resolving the contradiction between mechanical strength and thermal management in the mold underfill material.
2Productivity
If wiring density is increased by miniaturization, then the performance of electronic devices is improved, but heat dissipation becomes difficult
Solution Approach 1:
The patent changes the thermal conductivity parameter of the mold underfill material by incorporating alumina particles with high thermal conductivity (10-30 W/m·K) in controlled amounts (1-10 wt%). This parameter modification enables effective heat dissipation pathways in the packaging material, allowing high wiring density designs to maintain adequate thermal management.
3Productivity
If chips are stacked closer together, then the wiring density is increased, but the reliability decreases due to short-circuiting
Solution Approach 1:
The patent applies local quality control by using dual filler systems with different size ranges: fine silica (5-50 nm) for uniform distribution and CTE matching in the resin matrix, and coarser alumina (0.1-10 μm) for thermal conductivity. This localized optimization of filler distribution and properties ensures both mechanical integrity and thermal management at the specific locations where chips are stacked closely, maintaining reliability despite reduced pitch.
4Temperature
If alumina filler is added to improve thermal conductivity, then the thermal conductivity increases, but the viscosity of the liquid composition increases
Solution Approach 1:
The patent segments the filler system into two distinct size categories: nano-scale silica (5-50 nm) that disperses easily in the resin matrix without significantly increasing viscosity, and micro-scale alumina (0.1-10 μm) that provides thermal conductivity. This segmentation allows each filler type to perform its primary function while minimizing the negative impact on the flowability and injectability of the liquid mold underfill composition.
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 liquid epoxy resin composition effectively enhances thermal conductivity to 0.8 W/m·K or more, improving heat dissipation in densely packed semiconductor devices. It also significantly reduces the likelihood of short-circuiting in biased HAST tests, ensuring high reliability even with short bump-to-bump distances.
Implementation Method 1
the liquid epoxy resin composition gives a cured product having a thermal conductivity of 0.8 W/m·K or more and less than 1.2 W/m·K
Implementation Method 2
The latter is added to reduce the effect of light on wiring in electronic components
Data Source
AI summary
An object of the present invention is to provide a liquid epoxy resin composition suitable for use as a mold underfill material for TSV, which composition may provide an electronic component having high wiring density, satisfactorily releasing heat generated during its driving and having high reliability. The liquid epoxy resin composition of the present invention comprises an epoxy resin (A), a curing agent (B), an inorganic filler (C) consisting of a silica filler and an alumina filler and carbon black (D); the epoxy resin (A) comprises a specific aliphatic epoxy resin, the alumina filler has a specific particle size distribution, and the liquid epoxy resin composition gives a cured product having a thermal conductivity within a predetermined range. The liquid epoxy resin composition of the present invention gives a cured product having high thermal conductivity. Thus, in a semiconductor device that includes electronic components manufactured using the composition as a mold underfill material for TSV, deterioration of performance due to heat is suppressed. Furthermore, an electronic component manufactured using the liquid epoxy resin composition of the present invention as a mold underfill material for TSV exhibits sufficient reliability. Thus, the liquid epoxy resin composition of the present invention is highly suitable for use as a mold underfill material for TSV.