Semiconductor Device Anchor Layer Laser Structuring
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Solution Overview
Problem
The adhesion between conductive materials such as copper lead frames and epoxy resin molding in semiconductor devices is inadequate, leading to peeling issues due to thermal expansion differences and increased current loads, with existing anchor methods either reducing cross-sectional area or failing to provide sufficient anchoring.
Innovation Solution
A semiconductor device with an anchor layer featuring stripe-shaped concave portions formed by laser beam irradiation on the circuit pattern and external lead terminal, ensuring a surface roughness RMS ≥ 0.00175 mm and moving length L ≥ 1 mm², enhancing the anchoring effect and preventing peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional smooth circuit patterns and lead frames are used, then manufacturing is simple, but the molding resin peels off due to insufficient adhesion under thermal stress and current loads
Solution Approach 1:
The circuit pattern is designed with localized protrusions at specific positions where the molding resin contacts it. These protrusions create anchor holes that improve adhesion locally at the interface between the molding resin and the circuit pattern, while the rest of the circuit pattern maintains its conventional smooth structure for simple manufacturing.
Solution Approach 2:
The protrusions are pre-formed on the circuit pattern before the molding resin is applied. This preliminary structuring creates anchor holes in advance, allowing the molding resin to mechanically interlock with the circuit pattern, thereby preventing peeling before thermal stress or current loads are applied.
2Reliability
If anchor holes are formed in external lead terminals to improve adhesion, then molding resin peeling is prevented, but the cross-sectional area of the lead terminal is reduced
Solution Approach 1:
The adhesion-improving structure is segmented and placed only at specific locations on the circuit pattern where the molding resin contacts it, rather than being applied uniformly across the entire lead terminal. This localized approach provides anchoring where needed without reducing the overall cross-sectional area of the lead terminal.
3Power
If the width of external lead terminal is increased for high current capacity, then current handling is improved, but molding resin peeling occurs more remarkably
Solution Approach 1:
The circuit pattern incorporates localized protrusions at the interface with the molding resin, creating anchor holes that improve adhesion specifically at the contact regions. This allows the lead terminal to maintain its increased width for high current capacity without suffering from uniform peeling along the entire 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 solution effectively improves the adhesion of the molding resin, preventing peeling off even under thermal stress and high current conditions, while maintaining the structural integrity and conductivity of the lead frames.
Implementation Method 1
an anchor layer including a stripe-shaped concave portion which is formed in the circuit pattern by laser beam irradiation
Data Source
AI summary
A semiconductor device according to the invention includes an insulating substrate including an insulating plate, a circuit pattern that is formed on a front surface of the insulating plate, and a radiator plate that is fixed to a rear surface of the insulating plate, a semiconductor chip that is fixed to the circuit pattern, an external lead terminal that is connected to a surface electrode of the semiconductor chip through a wiring line, a molding resin that covers the insulating substrate, the semiconductor chip, the wiring line, and the external lead terminal such that a rear surface of the radiator plate and a portion of the external lead terminal are exposed, and an anchor layer including a stripe-shaped concave portion which is formed in the circuit pattern by laser beam irradiation.