Lead Frame Degating via Masked Oxidation
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Solution Overview
Problem
The existing methods for forming electronic components often result in lead frames being distorted due to varying adhesion strengths of mold compounds, leading to warping or bending during the degating process, which can cause misalignment and lower yields in downstream processing.
Innovation Solution
A method involving masking and oxidizing specific areas of the lead frame, such as the runner and gate regions, to reduce mold compound adhesion, using techniques like photoresist application and electrochemical, plasma, or wet oxidation, to create a controlled oxide thickness that facilitates easier removal of superfluous mold compound without damaging the lead frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mold compound is applied to encapsulate the die on the lead frame, then the die is protected and encapsulated, but the mold compound adheres strongly to the lead frame causing distortion during degating
Solution Approach 1:
The patent applies a release agent specifically to the gate region of the lead frame, creating a localized difference in surface properties. This allows the mold compound to adhere strongly to the die and most of the lead frame for proper encapsulation, while the gate region has reduced adhesion to facilitate clean separation during degating, thus preventing lead frame distortion.
2Ease of manufacture
If superfluous mold compound is removed from the lead frame, then the lead frame can be processed further, but the lead frame becomes bent or warped
Solution Approach 1:
The patent applies the release agent to the gate region before the mold compound is applied and cured. This preliminary action creates a pre-conditioned surface that controls adhesion during the encapsulation process itself, allowing the mold compound to be removed easily from the gate region after curing without causing warping or bending during the degating process.
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 method effectively reduces the adhesion of mold compound to the lead frame, allowing for easier and damage-free removal of excess compound, thereby minimizing warping and ensuring proper alignment and processing of electronic components.
Implementation Method 1
oxidizing the exposed area of the lead frame
Implementation Method 2
masking the lead frame to leave an exposed area corresponding with at least a runner area or a gate area
Data Source
AI summary
A method of forming an electronic component includes masking a lead frame to form a mask defining an exposed area, oxidizing the exposed area of the lead frame, wherein the mask inhibits oxidation of an unexposed area, and removing the mask from the lead frame following oxidizing. A lead frame can include a metal sheet patterned to define a pad region and leads. The metal sheet includes metal oxide in a select area. The pad region is substantially free of metal oxide.