Acicular CuO Surface Layer for Leadframe Resin Adhesion
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Solution Overview
Problem
The increasing heat generation in leadframe packages due to high integration of wiring and large currents leads to debonding issues at the interfaces between resins and leadframes, particularly in automotive applications, where reliability is a critical safety concern.
Innovation Solution
A leadframe with a surface layer composed primarily of acicular oxide containing CuO, which forms strong hydrogen bonds with resin hydroxyl groups, enhancing adhesion under high temperature conditions and reducing heat stress at the interface, thereby improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high integration of wiring and large current are used to increase power, then productivity and functionality are improved, but heat generation increases causing debonding at resin-leadframe interfaces
Solution Approach 1:
The patent changes the chemical composition parameters of the leadframe surface by forming a copper oxide layer with specific CuO concentration (higher than any other component) and controlled thickness (1 nm to 100 nm). This parameter change enables the surface to form hydrogen bonds with resin hydroxyl groups, maintaining adhesion under high temperature conditions generated by high power operation.
Solution Approach 2:
The patent creates a composite structure by forming a copper oxide surface layer on the copper-based leadframe substrate. This composite material system combines the electrical conductivity of copper with the adhesion properties of copper oxide, allowing the leadframe to simultaneously handle high current and maintain strong bonding to the resin package under thermal stress.
2Temperature
If high temperature conditions occur during packaging and operation, then curing and functionality are achieved, but adhesion between resin and leadframe deteriorates
Solution Approach 1:
The patent changes the thermal stability parameters of the leadframe surface through copper oxide formation. The copper oxide layer has specific thermal properties that allow it to maintain hydrogen bonding capability with resin hydroxyl groups at high temperatures, preventing adhesion deterioration during the curing process and subsequent high-temperature operation.
Solution Approach 2:
The patent converts the potentially harmful effect of high temperature on adhesion into a benefit by using the copper oxide layer's ability to form thermally stable hydrogen bonds. The copper oxide surface layer acts as a thermal buffer that maintains chemical bonding capability even when exposed to elevated temperatures during packaging and operation.
3Ease of manufacture
If conventional leadframe surfaces are used, then manufacturing is simple, but adhesion to resin deteriorates under high temperature conditions
Solution Approach 1:
The patent applies a surface treatment process that oxidizes the copper leadframe surface to create a copper oxide layer with controlled composition and thickness. This parameter change in surface chemistry can be integrated into existing manufacturing processes, maintaining ease of production while dramatically improving adhesion performance under thermal stress.
Solution Approach 2:
The patent applies the copper oxide surface layer only to the specific regions of the leadframe that contact the resin package, rather than modifying the entire leadframe structure. This localized surface treatment maintains manufacturing simplicity while providing enhanced adhesion precisely where needed at the resin-leadframe interface.
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 leadframe package maintains satisfactory adhesion to the resin even under high temperature conditions, significantly enhancing the reliability of the package by suppressing debonding and improving shear strength.
Implementation Method 1
CuO can form hydrogen bonds with hydroxyl groups contained in the molecular structure of a resin
Data Source
AI summary
A leadframe includes a substrate and a surface layer covering the substrate. The surface layer includes an acicular oxide containing CuO at a higher concentration than any other component of the acicular oxide. A leadframe package includes the leadframe, a semiconductor chip mounted on the leadframe, and a resin that covers the semiconductor chip and at least a part of the leadframe.