Leadless Package Manufacturing via Etched Lead Isolation
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Solution Overview
Problem
The existing methods for manufacturing leadless packages result in saw burrs during dicing, which cause attachment issues and potential shorting between leads due to differing material properties and friction, leading to suboptimal package flatness and reliability.
Innovation Solution
The method involves separating adjacent leads by etching, followed by singulating packages through the encapsulation material, reducing the risk of saw burrs and lead smearing by avoiding the cutting of connecting bars, and allowing for electrical testing in leadframe strip form before individual singulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single dicing step is used to cut through both encapsulation material and leadframe strip, then manufacturing process is simplified, but saw burrs are generated that extend beyond the bottom surface of leads causing attachment issues
Solution Approach 1:
The patent divides the dicing process into two separate steps: first dicing through the encapsulation material only, then a second dicing step through the leadframe strip. This segmentation allows each dicing operation to be optimized for its specific material, preventing saw burrs from extending beyond the lead bottom surface while maintaining manufacturing efficiency.
2Productivity
If saw blade cuts through leadframe strip at high speed, then productivity is increased, but friction causes leads to smear along outer surface and into encapsulation material creating shorting
Solution Approach 1:
The patent separates the dicing operation into two distinct steps: first dicing through encapsulation material, then second dicing through the leadframe strip. This allows the second dicing to be performed at optimized speeds that prevent lead smearing and electrical shorting while maintaining overall productivity through efficient process sequencing.
Solution Approach 2:
The first dicing step removes the encapsulation material before the second dicing step processes the leadframe strip. This preliminary action prepares the workpiece by removing the softer material first, allowing the subsequent dicing of the leadframe to be performed with parameters that prevent lead deformation and smearing.
3Loss of time
If single dicing step is used, then manufacturing time is reduced, but saw burrs prevent packages from lying flat on board surface
Solution Approach 1:
The patent implements a two-step dicing process where the first step cuts through encapsulation material and the second step cuts through the leadframe strip. This segmentation eliminates saw burrs from extending beyond the lead bottom surface, ensuring packages lie flat on the board while the combined process maintains efficient manufacturing cycle time.
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 minimizes saw burrs and lead smearing, enhances package flatness and reliability, and increases throughput by separating leads through an etch step followed by dicing, improving board attachment and reducing the risk of shorting.
Implementation Method 1
the adjacent leads are separated by etching through the leads, thereby providing electrical isolation of the adjacent packages
Data Source
AI summary
Embodiments of the present disclosure are directed to leadframe strips and methods of forming packages that include first separating adjacent leads of a leadframe strip and subsequently singulating components into individual packages. In one embodiment, the adjacent leads are separated by etching through the leads, thereby providing electrical isolation of the adjacent packages. In that regard, if desired, the individual adjacent packages may be electrically tested in leadframe strip form. Subsequently, the individual packages are formed by sawing through the encapsulation material.