Lead-frame Silver Surface Adhesion Treatment
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Solution Overview
Problem
Current lead-frame structures face challenges in achieving strong adhesion between silver surfaces and resin materials, leading to potential delamination issues during the production of surface mount electronic devices, especially under severe testing conditions like the IPC/JEDEC J-STD-20 MSL standard, due to moisture absorption and thermal stress.
Innovation Solution
A method involving electrolytically treating the silver surface of lead-frame structures with a solution containing hydroxide compounds, such as alkali metal hydroxides, to enhance adhesion, while minimizing the copper surface area exposed, resulting in a treated silver surface with improved bonding to resin materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver surface is used for electrical connection, then electrical conductivity is improved, but adhesion to resin material deteriorates
Solution Approach 1:
The patent applies different surface treatments to different regions of the lead-frame. The connection region is coated with silver for electrical conductivity, while the mold contact region is left as copper or treated differently for adhesion. This local differentiation resolves the contradiction by allowing each region to have the properties needed for its specific function.
Solution Approach 2:
The patent introduces an intermediate layer or surface treatment between the silver coating and the resin mold. This intermediary layer, which could be a specific copper treatment or a transition layer, mediates the interaction between the conductive silver surface and the adhesive resin, enabling both electrical conductivity and strong adhesion.
2Strength
If copper surface area is increased, then adhesion to resin material is improved, but electrical conductivity deteriorates
Solution Approach 1:
The patent creates spatial differentiation where copper surfaces are exposed in mold contact regions for adhesion, while silver coatings are maintained in connection regions for electrical conductivity. This local quality assignment allows the system to optimize for adhesion where needed without compromising electrical performance.
3Reliability
If silver coating is applied, then electrical conductivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the lead-frame surface into distinct functional zones: connection regions requiring silver coating and mold contact regions where copper is sufficient or differently treated. This segmentation allows selective application of complex silver plating only where necessary, reducing overall manufacturing complexity while maintaining electrical performance.
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
This approach results in excellent adhesion between the treated silver surface and the resin, even under severe testing conditions, reducing the risk of delamination and improving the reliability and quality of surface mount electronic devices, while also being environmentally friendly and cost-effective by minimizing the use of hazardous materials and reducing production complexity.
Implementation Method 1
electrolytically treating the silver surface of lead-frame structures with a solution containing hydroxide compounds
Data Source
AI summary
A method of producing a lead-frame structure having two faces and exposing a treated silver surface on at least one of the two faces, the treated silver surface(s) serving the wire bonding, which yields a surface which, after applying resin to it, has excellent adhesion even under severe testing conditions, such as the IPC/JEDEC J-STD-20 MSL standard, and a method of producing a surface mount electronic device including a lead-frame or lead-frame entity and at least one semiconductor device mounted thereon, wherein the lead-frame or lead-frame entity exposes a treated silver surface on at least one of the two faces, wherein the treated silver surface(s) serve(s) the wire bonding, and wherein a resin is applied to the lead-frame or lead-frame entity, which method yields excellent adhesion of the surface of the lead-frame or lead-frame entity even under severe testing conditions.