Curved Die Pad Interface for Thermal Stress Resistance
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Solution Overview
Problem
Semiconductor packages face reliability and lifespan issues due to detachment and cracking caused by thermal stress, primarily resulting from differences in linear expansion coefficients between the semiconductor chip, lead frame, die bond resin, and mold resin, leading to reduced moisture resistance, insulation, and heat dissipation.
Innovation Solution
Introducing unevenness on the bonding interface between the die pad and semiconductor chip increases the bonding area, using mechanical or chemical methods like punching, laser processing, or etching, to strengthen the bond and reduce thermal stress-induced detachment and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat bonding interface is used between die pad and semiconductor chip, then the manufacturing process is simple, but detachment occurs under thermal stress due to linear expansion coefficient differences
Solution Approach 1:
The patent applies curvature by forming an arc-shaped bonding interface between the die pad and semiconductor chip instead of a flat interface. The arc shape with a specific radius of curvature increases the bonding area and distributes thermal stress more evenly, preventing detachment while maintaining manufacturing feasibility through standard bonding processes.
2Strength
If the bonding interface area is increased to strengthen bonding, then detachment resistance improves, but the device structure becomes more complex
Solution Approach 1:
The arc-shaped bonding interface increases the bonding area between die pad and semiconductor chip without requiring additional components or complex multi-layer structures. The curved geometry naturally provides larger contact area and better stress distribution, achieving enhanced bonding strength through geometric optimization rather than structural complexity.
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 enhanced bonding interface improves the reliability and lifespan of semiconductor devices by minimizing detachment and cracking, even under thermal stress, thereby maintaining moisture resistance and heat dissipation.
Implementation Method 1
a semiconductor chip is bonded by a die bond resin onto a die pad of a lead frame
Implementation Method 2
when a temperature cycle of heat generation and cooling is repeated due to a temperature change of an external environment and a temperature change of a semiconductor chip itself, the die bond resin may be detached from the die pad or the semiconductor chip... due to a difference in linear expansion coefficient among the semiconductor chip, the lead frame, the die bond resin and the mold resin
Data Source
AI summary
A semiconductor device in the preferred embodiment includes: a lead frame comprising a die pad and an electrode terminal; and at least one semiconductor chip bonded to a surface of the die pad, wherein the lead frame excluding a bottom surface thereof and the semiconductor chip are sealed by a sealing resin, and an unevenness is introduced on a bonding interface between the surface of the die pad and the semiconductor chip.