Lead Frame Sidewall Roughness for Resin Adhesion in Flip-Chip Packages
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Solution Overview
Problem
In semiconductor devices using flip chip bonding, insufficient adhesion between the resin and the lead frame leads to voids and solder cracks, increasing resistance and potentially causing device malfunction.
Innovation Solution
A semiconductor device with a lead frame having a first opening portion where the side wall surface has a larger average surface roughness than the upper surface, enhancing adhesion with the resin through an anchor effect, thereby preventing voids and solder cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If flip chip bonding is used to achieve high densification and high integration, then the package size can be reduced, but the chip becomes vulnerable to external stress and adhesion between resin and lead frame becomes insufficient
Solution Approach 1:
The patent applies local quality by creating a roughened surface layer specifically at the interface between the lead frame and resin, while keeping other surfaces smooth. This localized surface treatment enhances adhesion only where needed (at the resin-lead frame interface) without affecting other functional areas of the lead frame, thus resolving the contradiction between small package size and reliable adhesion.
2Reliability
If the chip is sealed with resin to protect from external stress, then the chip is protected, but voids and solder cracks are generated near the interface between resin and lead frame
Solution Approach 1:
The patent applies preliminary action by pre-treating the lead frame surface with roughening treatment before resin filling. This creates a surface structure that promotes better resin penetration and adhesion in advance, preventing the formation of voids and solder cracks during the sealing process, thus maintaining chip protection without generating harmful defects.
3Reliability
If roughening treatment is applied to increase adhesion, then adhesion between resin and lead frame is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies parameter changes by modifying the surface roughness parameter of the lead frame through controlled roughening treatment. This changes the physical state of the lead frame surface to enhance adhesion, while the treatment process itself (such as mechanical roughening or chemical etching) can be integrated into existing manufacturing workflows, minimizing the increase in overall process 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 adhesion between the lead frame and the resin significantly reduces the occurrence of voids and solder cracks, improving the reliability and reducing defects in semiconductor devices.
Implementation Method 1
a side wall surface of the lead frame in the first opening portion has a larger average surface roughness than an upper surface of the lead frame
Implementation Method 2
sufficiently securing adhesion between a resin and a lead frame
Data Source
AI summary
There is provided a semiconductor device including: a lead frame including a first opening portion; a resin filled in the first opening portion; and a semiconductor element electrically connected to the lead frame, wherein a side wall surface of the lead frame in the first opening portion has a larger average surface roughness than an upper surface of the lead frame.