Thin Adhesive Polyimide Film for Semiconductor Lead Frame Protection
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Solution Overview
Problem
During the production of semiconductor devices, temporary protective films attached to lead frames face issues such as void generation and reduced peelability due to increased thermal history, leading to potential sealing layer wraparound and adhesive residue problems.
Innovation Solution
A temporary protective film comprising a polyimide support film with an adhesive layer on one or both surfaces, where the adhesive layer's thickness is less than 8 μm, providing high adhesiveness and heat resistance, and a non-adhesive layer on the opposite surface to prevent sticking, is used to protect the lead frame during sealing molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a temporary protective film is attached to the lead frame during sealing molding, then the lead frame is protected from sealing material wraparound, but voids may generate at the interface between the film and lead frame due to thermal history
Solution Approach 1:
The adhesive layer thickness is changed from conventional thicker layers to specifically less than 8 μm. This parameter change reduces the volume where voids can form while maintaining sufficient adhesion strength to prevent film detachment during sealing molding, thus resolving the contradiction between protection and void generation
Solution Approach 2:
The film structure is designed with different layers having different properties: the adhesive layer (less than 8 μm) provides localized strong bonding at the lead frame interface to prevent void formation, while the support film provides overall structural protection. This local differentiation of quality allows simultaneous achievement of protection and void suppression
2Strength
If the adhesive layer thickness is increased to improve adhesiveness, then the film adheres better to the lead frame, but peelability after sealing molding deteriorates
Solution Approach 1:
The adhesive layer thickness is optimized to less than 8 μm, which is a critical parameter threshold. At this thickness, the adhesive provides sufficient bonding strength during sealing molding while maintaining adequate peelability afterward, resolving the contradiction between strong adhesion and easy removal
Solution Approach 2:
The temporary protective film is designed as a disposable component that serves its protective function during sealing molding and then can be easily removed. The optimized thin adhesive layer enables the film to fulfill its temporary purpose without leaving excessive adhesive residue, facilitating easy peeling after use
3Reliability
If the temporary protective film is subjected to higher temperatures and longer durations during sealing molding, then the sealing process is more thorough, but void generation and peelability issues become apparent
Solution Approach 1:
The adhesive layer thickness is changed to less than 8 μm, which modifies the thermal and mechanical behavior of the film during sealing molding. This parameter change allows the film to withstand higher temperatures and longer durations without generating voids or losing peelability, thus enabling more thorough sealing while avoiding harmful effects
Solution Approach 2:
The adhesive layer is designed with optimized thickness before the sealing molding process begins. This preliminary optimization ensures that during subsequent high-temperature and long-duration sealing, the film maintains its integrity and adhesion properties, preventing void formation and peelability issues
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 solution effectively suppresses void generation and improves peelability, ensuring satisfactory adhesiveness, reducing warpage and adhesive residue, and preventing sealing material wraparound, thereby enhancing the semiconductor device production process.
Implementation Method 1
an adhesive layer provided on one surface or both surfaces of the support film
Data Source
AI summary
A temporary protective film including a support film and an adhesive layer provided on one surface or both surfaces of the support film. The support film is a polyimide film. The thickness of the adhesive layer is less than 8 μm.