Mold Release Film Surface Roughness for Semiconductor Packaging
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Solution Overview
Problem
In the production of semiconductor packages, large packages such as wafer-level packages face issues with wrinkles and pinholes when using mold release films, leading to poor appearance and reduced productivity, while increasing surface roughness to prevent these issues can result in chipping or cracking during the singulation process and increased raw material costs.
Innovation Solution
A mold release film with specific surface irregularities, an arithmetic mean roughness (Ra) of 1.3 to 2.5 μm, and a peak count (RPc) of 80 to 200, and a thickness of 16 to 75 μm, made of fluororesin such as ethylene/tetrafluoroethylene copolymer, is used to prevent wrinkles and pinholes, while maintaining followability and adhesion to the ink layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surface roughness of the mold release film is increased to prevent wrinkles and pinholes, then the appearance quality is improved, but chipping or cracking occurs during singulation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface roughness parameters (Ra: 0.03-0.5 μm, Rz: 0.06-1.0 μm) of the mold release film. This optimization resolves the contradiction by finding the optimal roughness range that prevents wrinkles and pinholes during molding while avoiding excessive roughness that would cause chipping or cracking during subsequent singulation processes.
2Reliability
If a mold release film is used to prevent adhesion between resin-encapsulation portion and mold, then the releasability is improved, but wrinkles and pinholes are formed on the resin surface
Solution Approach 1:
The patent uses parameter changes by optimizing the surface roughness parameters (Ra and Rz values) of the mold release film. The controlled roughness provides sufficient adhesion for releasability while preventing the formation of wrinkles and pinholes during the molding process, thus resolving the contradiction between releasability and surface quality.
3Strength
If the thickness of the mold release film is increased to prevent pinholes, then the structural integrity is improved, but the followability to cavity surface deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness of the mold release film. The controlled thickness provides sufficient structural integrity to prevent pinholes while maintaining adequate followability to conform to the cavity surface during molding, thus resolving the contradiction between film integrity and 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 mold release film effectively prevents wrinkles and pinholes, reduces chipping or cracking during singulation, and enhances the adhesion of the ink layer, thereby improving the productivity and quality of semiconductor packages without increasing raw material costs.
Implementation Method 1
the mold release film is stretched along the cavity surface of the mold by vacuum suction and brought in such a state as closely in contact with the cavity surface
Data Source
AI summary
A mold release film to be disposed on a cavity surface of a mold in a method for producing a semiconductor package wherein a semiconductor element is disposed in the mold and encapsulated with a curable resin to form a resin-encapsulation portion, characterized in that it has a first surface to be in contact with the curable resin at the time of forming the resin-encapsulation portion, and a second surface to be in contact with the cavity surface, at least one of the first surface and the second surface has irregularities formed thereon, and the surface having irregularities formed thereon, has an arithmetic mean roughness (Ra) of from 1.3 to 2.5 μm and a peak count (RPc) of from 80 to 200; and a process for producing a semiconductor package by using the mold release film.