Lead Frame Bonding Resin for Thermal-Stress Semiconductor Packaging
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Solution Overview
Problem
Conventional semiconductor devices face malfunctions due to thermal stress, which causes detachment of the sealing resin at the interface with the bonded region, leading to cracks in conductive members like solder and wire breakage.
Innovation Solution
A semiconductor device design that includes a resin composition with greater bonding strength than the sealing resin, covering the bonded regions between conductive members and the lead frame, thereby preventing detachment of the sealing resin under thermal load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing resin is used to cover the bonded region, then the semiconductor device is protected and sealed, but the bonding strength is insufficient under thermal load causing detachment
Solution Approach 1:
The patent applies composite materials by using a resin composition that combines multiple components: a base resin (epoxy, polyester, or phenolic resin), a reactive diluent (glycidyl ether or carboxylic acid group-containing compound), and optionally a coupling agent. This composite formulation achieves superior bonding strength to both the lead frame and conductive members compared to conventional sealing resin alone, preventing detachment under thermal load while maintaining a relatively simple overall device structure.
Solution Approach 2:
The patent implements local quality by applying the resin composition specifically to the bonded region where the conductive member meets the lead frame, rather than using it throughout the entire sealing structure. This localized application provides enhanced bonding strength precisely where thermal stress concentrates, while the rest of the device maintains its original simple structure with conventional sealing resin.
2Reliability
If thermal load is applied during operation, then the semiconductor device functions normally, but thermal stress causes detachment of sealing resin at the bonded region interface
Solution Approach 1:
The resin composition acts as an intermediary layer between the lead frame and the conductive member (solder or wire). This intermediate resin layer with enhanced bonding properties mediates the thermal stress by providing strong adhesion to both substrates, preventing the detachment that would otherwise occur at the interface under thermal cycling conditions. The reactive diluent and coupling agents in the resin composition specifically enhance this intermediary bonding function.
3Reliability
If conventional sealing resin is used, then the device structure is simple, but cracks occur in conductive members and wires detach under thermal load
Solution Approach 1:
The patent applies the resin composition in advance to the bonded region before final assembly and sealing. This preliminary application ensures that the enhanced-bonding resin is in place to prevent cracks and detachment before the device undergoes thermal cycling during operation. The resin composition is applied to the lead frame or conductive member surface prior to mounting, creating a pre-established strong bonding 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 proposed solution effectively prevents detachment of the sealing resin and subsequent malfunctions, ensuring reliable operation of the semiconductor device under thermal stress.
Implementation Method 1
The resin composition has a greater bonding strength with the lead frame than a bonding strength between the sealing resin and the lead frame and also has a greater bonding strength with the conductive member than a bonding strength between the sealing resin and the conductive member
Implementation Method 2
Thermal stress due to such thermal load concentrates on the bonded region where the conductive members such as solder or a wire and the lead frame are bonded
Data Source
AI summary
A semiconductor device includes a semiconductor element, a lead frame, a conductive member, a resin composition and a sealing resin. The semiconductor element has an element front surface and an element back surface facing away in a first direction. The semiconductor element is mounted on the lead frame. The conductive member is bonded to the lead frame, electrically connecting the semiconductor element and the lead frame. The resin composition covers a bonded region where the conductive member and lead frame are bonded while exposing part of the element front surface. The sealing resin covers part of the lead frame, the semiconductor element, and the resin composition. The resin composition has a greater bonding strength with the lead frame than a bonding strength between the sealing resin and lead frame and a greater bonding strength with the conductive member than a bonding strength between the sealing resin and conductive member.