Laser-Textured Lead Frame for Resin Adhesion
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Solution Overview
Problem
Existing semiconductor devices face issues with adhesion between nickel-plated lead frames and molding resin, leading to potential separation due to the hardness of nickel plating, difficulty in miniaturization, and reduced productivity, as well as compromised wire bondability and flatness of the lead frame.
Innovation Solution
The implementation of scale-like portions on the metal plating of the lead frame, formed through laser spot irradiation, which provide an anchor effect to enhance adhesion with the molding resin, allowing for miniaturization and high productivity without impairing the lead frame's flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dimpling is performed to suppress separation of molding resin, then the lead frame requires large area which prevents miniaturization
Solution Approach 1:
The invention replaces the mechanical dimpling process with laser irradiation to create surface roughness. The laser method can generate effective adhesion structures in a much smaller area compared to mechanical dimpling, allowing the lead frame to achieve good separation resistance while maintaining a compact size suitable for miniaturization of semiconductor devices.
2Productivity
If repeated laser spot irradiation is performed to form scale-like portions, then productivity increases, but thermal change of properties or deformation may occur
Solution Approach 1:
The invention uses periodic laser spot irradiation to form scale-like portions on the nickel plating surface. By controlling the irradiation pattern and parameters, the laser creates a roughened surface structure that enhances adhesion without causing excessive thermal accumulation or deformation, thus achieving both high productivity and manufacturing precision.
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 scale-like portions improve adhesion between the lead frame and molding resin, preventing separation, enabling miniaturization and maintaining high reliability and productivity while maintaining wire bondability and ensuring the flatness of the lead frame.
Implementation Method 1
formed through laser spot irradiation
Data Source
Figure 1~2
Figure 3~5
Figure 6~8
AI summary
A scale-like portion (3) wherein metal plating is changed into a scale-like form is provided by continuously carrying out laser spot irradiation on a lead frame (2), the front surface of which is coated with the metal plating. The scale-like portion (3) is disposed in an optional portion of the lead frame (2), for example, in the vicinity of a gate break mark (8a), in an outer peripheral portion in a region sealed with a molding resin (8), or around a semiconductor element (1). The adhesion between the lead frame (2) and the molding resin (8) improves owing to the anchor effect of the scale-like portion (3), and it is thus possible to suppress the molding resin (8) separating from the lead frame (2).