Release Film for Semiconductor Packaging with Uniform Stretchability
Solution Overview
Problem
Existing release films used in semiconductor packaging are prone to local stretching and breakage under load, leading to non-uniform thickness and internal stress in packages, which can damage semiconductor chips, especially at corners where high impact is exerted during the sealing process.
Innovation Solution
A single-layer film made from a blend of ETFE, PFA, FEP, ECTFE, or PMP resins with specific melt flow rates and molecular weight distributions, ensuring excellent breakage resistance and uniform stretchability, is developed. The film is produced using an extrusion molding method with controlled shear rates and blending ratios to achieve optimal properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional release films are used in semiconductor packaging, then the films can be stretched to follow the mold during sealing, but the films are prone to local stretching and breakage under load, leading to non-uniform thickness and internal stress in packages
Solution Approach 1:
The patent changes the molecular weight distribution parameter of the resin by blending polymers with different molecular weights (specifically, a polymer with Mw/Mn ≥ 2.0 and another with Mw/Mn < 2.0 in a weight ratio of 3:7 to 7:3). This parameter change enables the film to achieve both high breakage resistance and uniform thickness during stretching, resolving the contradiction between strength and manufacturing precision.
Solution Approach 2:
The patent creates a composite resin system by blending two polymers with different molecular weight distributions. The combination of a high polydispersity polymer (Mw/Mn ≥ 2.0) and a low polydispersity polymer (Mw/Mn < 2.0) produces a composite material that exhibits both superior breakage resistance and uniform stretchability, solving the contradiction between strength and thickness uniformity.
2Productivity
If the sealing area is increased to improve productivity, then more semiconductor chips can be sealed at one time, but larger sealing areas exert greater loads on the release film, increasing the risk of local stretching and breakage
Solution Approach 1:
The patent modifies the molecular weight distribution parameters of the resin blend to achieve optimal balance between strength and uniformity. By specifying Mw/Mn ≥ 2.0 for one polymer and Mw/Mn < 2.0 for another, with a weight ratio of 3:7 to 7:3, the film gains sufficient breakage resistance to withstand the increased loads from larger sealing areas while maintaining thickness uniformity, thus enabling higher productivity without compromising reliability.
Solution Approach 2:
The patent employs a composite resin system combining two polymers with different molecular weight distributions. This composite material provides the enhanced mechanical strength required for large-area sealing operations while maintaining uniform stretchability, allowing productivity improvement without sacrificing film integrity under increased loads.
3Shape
If the release film is stretched to follow the mold during sealing, then the film conforms to the mold surface, but the film becomes non-uniform in thickness locally, causing bulged shapes called 'horns' at corners
Solution Approach 1:
The patent optimizes the molecular weight distribution parameters by blending polymers with specific Mw/Mn ratios (≥2.0 and <2.0 in a 3:7 to 7:3 weight ratio). This parameter optimization enables the film to stretch uniformly across the mold surface, achieving excellent mold followability while preventing local thickness variations and horn formation at corners.
Solution Approach 2:
The patent creates a homogeneous resin blend with controlled molecular weight distribution that ensures uniform stretching behavior across the entire film. The specific combination of polymers with different Mw/Mn ratios produces a homogeneous material structure that stretches evenly during molding, maintaining thickness uniformity while achieving complete mold followability.
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 film exhibits excellent breakage resistance and uniform stretchability, preventing rupture under large loads and ensuring uniform thickness, thus reducing the risk of damage to semiconductor chips and improving package reliability.
Implementation Method 1
the film is made of a blend resin of two kinds of resins both belonging to any one of the following ETFE, PFA, FEP, ECTFE and PMP, the melt flow rate of the film to be measured by the following measurement method is at least 6 g/10 min. and less than 20 g/10 min., and α of the film to be measured by the following measurement method is at least 0.99
Data Source
AI summary
To provide a film excellent in breakage resistance and uniform stretchability, and a method for its production. The film is a single-layer film characterized in that it is made of a blend resin of two kinds of resins both belonging to any one of ETFE, PFA, FEP, ECTFE and PMP, wherein the melt flow rate of the film is at least 6 g/10 min. and less than 20 g/10 min., and α of the film as measured by a prescribed measurement method is at least 0.99.