Semiconductor Package Surface Roughening for Delamination Resistance
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Solution Overview
Problem
High-power semiconductor package assemblies are prone to delamination due to moisture ingress and ionic contamination, which is exacerbated by mechanical stress and inadequate adhesion between the semiconductor package and the moulding resin, and existing methods to enhance adhesion, such as roughening the lead frame, increase costs and cause solder wettability and pattern recognition issues.
Innovation Solution
A method involving a surface roughening treatment using a chemical solution, like a photoresist layer stripping agent, applied to the semiconductor package before encapsulation with moulding resin, to improve adhesion and reduce delamination risks, while avoiding the negative impacts of pre-existing surface roughening processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lead frame surface is roughened to enhance adhesion between the semiconductor package and moulding resin, then delamination resistance is improved, but manufacturing cost increases due to additional etching and finishing processes
Solution Approach 1:
The patent applies a chemical solution treatment that modifies the surface parameters of the lead frame, semiconductor die structure, and bond elements simultaneously. This chemical parameter change creates surface roughness and activation without requiring mechanical etching or additional finishing processes, thereby reducing manufacturing costs while maintaining delamination resistance
Solution Approach 2:
The patent combines multiple surface treatment functions into a single step by applying the chemical solution to the complete semiconductor package. This merges the lead frame roughening, semiconductor surface activation, and bond element preparation into one integrated process, eliminating separate etching and finishing operations and reducing overall manufacturing complexity and cost
2Reliability
If the lead frame surface is roughened to enhance adhesion, then delamination resistance is improved, but solder wettability deteriorates
Solution Approach 1:
The patent applies the chemical solution treatment selectively to specific surfaces that require adhesion enhancement (lead frame, semiconductor die structure, and bond elements) while preserving the solderable surfaces. This localized quality approach ensures that roughness is created only where needed for bonding, maintaining solder wettability on surfaces that require smooth finishes
Solution Approach 2:
The patent performs the chemical solution treatment as a preliminary step before soldering operations. This preliminary action prepares the surfaces for subsequent bonding processes while allowing time for any adverse effects to be mitigated before solder application, ensuring both adhesion and solder wettability are optimized
3Reliability
If the lead frame surface is roughened to enhance adhesion, then delamination resistance is improved, but pattern recognition in DACA processes deteriorates
Solution Approach 1:
The patent applies the chemical solution treatment to create surface roughness locally on the lead frame surfaces that require adhesion enhancement, while preserving the patterned surfaces used for optical recognition. This selective application ensures that pattern recognition systems can still function properly while achieving improved bonding adhesion in critical areas
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
Significantly enhances the adhesion between the semiconductor package and the moulding resin, reducing delamination risks and mitigating adverse effects on solder wettability and pattern recognition, while maintaining cost-effectiveness and process reliability.
Implementation Method 1
subjecting the exposed surfaces of the first frame side of the lead frame, the adhering connections and the at least one bond element of the at least one semiconductor package to a surface roughening treatment using a chemical solution
Data Source
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AI summary
The disclosure proposes a method for manufacturing a semiconductor package assembly comprising the steps of i) forming at least one semiconductor package by means of the sub-steps: i1) providing a lead frame having a first frame side and a second frame side opposite to the first frame side; i2) adhering at least one semiconductor die structure having a first die side and a second die side opposite to the first side with its second die side on the first frame side of the lead frame, resulting in a first conductive connection between the lead frame and the at least one semiconductor die structure; i3) adhering at least one bond element on the first die side of the at least one semiconductor die structure and/or on the first frame side of the lead frame, resulting in at least one further conductive connection between the at least one bond element and the at least one semiconductor die structure and between at least a further bond element and the lead frame; and ii) encapsulating the at least one semiconductor package with a moulding resin, thereby forming at least one encapsulated semiconductor package assembly; wherein, prior to step ii) but after step i3), the method further comprises the step of: iii) subjecting the exposed surfaces of the first frame side of the lead frame, the adhering connections and the at least one bond element of the at least one semiconductor package to a surface roughening treatment using a chemical solution.