Lead Frame Screen Printing for Selective Plating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The manufacturing of lead frames for integrated circuits faces challenges in optimizing system performance while reducing production costs, particularly due to the inefficiencies and high costs associated with using precious metals for selective plating, and the limitations of existing methods such as mechanical masks and photoresists which are costly and slow, and electrophoretic materials which decrease production speed.
Innovation Solution
The use of screen printing, specifically rotary screen printing with a metallic mesh and gelatine occlusion, to selectively deposit coating layers on predetermined areas of the substrate, allowing for precise and cost-effective manufacturing of lead frames with improved solderability and adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate is coated with precious metals such as palladium or gold to guarantee high solderability, then the solderability is improved, but the manufacturing cost increases dramatically
Solution Approach 1:
The patent applies selective plating to deposit precious metal coating layers only on predetermined areas of the substrate that require solderability, rather than coating the entire surface. This localized approach maintains high solderability where needed while dramatically reducing the quantity of precious metal consumed.
Solution Approach 2:
The substrate surface is segmented into areas requiring solderability and areas that do not. By dividing the coating requirement into specific zones, the patent enables precise application of precious metals only where functionally necessary, optimizing both performance and cost.
2Quantity of substance
If mechanical masks are used for selective plating to reduce precious metal usage, then the amount of precious metal is reduced, but the precision of plating deteriorates due to gaps between mask and substrate
Solution Approach 1:
The patent replaces mechanical mask systems with a screen printing approach where a screen with precisely controlled open areas directly defines the plating pattern. This substitution eliminates the gap-related precision problems of mechanical masks by using the screen structure itself to control material deposition areas.
Solution Approach 2:
The screen acts as an intermediary element between the plating source and the substrate. It mediates the deposition process by allowing precious metal to pass through only through its open areas, ensuring precise pattern transfer without the need for close mechanical contact between mask and substrate.
3Manufacturing precision
If photoresist masks are used for selective plating to improve precision, then the plating precision is improved, but the manufacturing cost increases and production speed decreases
Solution Approach 1:
The patent uses a reusable screen structure instead of consumable photoresist masks. The screen can be used repeatedly for multiple plating operations, eliminating the need for continuous photoresist application, exposure, and development steps, thereby dramatically increasing production speed while maintaining precision.
Solution Approach 2:
The patent extracts and eliminates the photoresist processing steps from the selective plating process. By removing these time-consuming chemical processing steps and replacing them with a direct screen printing approach, production speed is significantly improved while plating precision is maintained through the screen's precise geometry.
4Quantity of substance
If electrophoretic materials are used for selective plating to reduce cost, then the material cost is reduced, but the production speed decreases
Solution Approach 1:
The patent replaces electrophoretic deposition with a screen printing mechanical system. This substitution eliminates the need for complex electrophoretic equipment and processing steps, enabling faster production while using simple, cost-effective screen materials that do not require expensive electrophoretic materials.
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 method significantly reduces material waste and manufacturing costs, increases production speed, and enables the production of lead frames with high solderability and adhesion properties, facilitating efficient and economical large-scale production, including reel-to-reel processes.
Implementation Method 1
the formation of at least one coating layer on one or more predetermined portions of the surface of the substrate comprises the delimitation of said one or more predetermined portions by means of screen printing
Data Source
AI summary
An embodiment of a method and an apparatus for manufacturing lead frames are described. For example, a coating layer is formed on one or more predefined portions of the surface of the substrate of the lead frame by delimiting the predefined portions by means of screen printing. The employment of screen printing may allow obtaining large amounts of lead frames with excellent electronic and structural properties in a quick and cost-effective way.