Leadframe Singulation via Partial Tie Bar Etching
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Solution Overview
Problem
Existing semiconductor package technologies face challenges in efficiently singulating leadframes with tie bars using conventional sawing or high-pressure water jet processes, as these methods often require complex cutting paths and can damage the leadframe structures.
Innovation Solution
The implementation of a leadframe design that allows for singulation using a saw or high-pressure water jet process, where tie bars are partially or fully etched before encapsulation, enabling the application of an electrically conductive layer and subsequent full singulation, which enhances the wettable surface for soldering and improves packaging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional sawing or high-pressure water jet processes are used to singulate leadframes with tie bars, then singulation can be achieved, but the cutting paths become complex and the leadframe structures may be damaged
Solution Approach 1:
The tie bars are partially etched before encapsulation to create a pre-defined separation path. This preliminary action simplifies the subsequent singulation process by providing a predetermined weak point where the cut should occur, eliminating the need for complex cutting paths around intact tie bars.
Solution Approach 2:
The tie bars are divided into multiple segments through partial etching, creating distinct regions that are easier to separate. This segmentation allows the singulation process to follow a simpler path through the etched portions rather than navigating around solid tie bar structures.
2Productivity
If conventional sawing or high-pressure water jet processes are used to singulate leadframes with tie bars, then singulation can be achieved, but the leadframe structures may be damaged
Solution Approach 1:
The tie bars are partially etched before encapsulation to create a pre-defined separation path. This preliminary action simplifies the subsequent singulation process by providing a predetermined weak point where the cut should occur, eliminating the need for complex cutting paths around intact tie bars.
Solution Approach 2:
Portions of the tie bars are removed through partial etching, extracting material to create a separation path. This reduces the amount of material that would otherwise need to be cut through during singulation, minimizing stress and potential damage to the leadframe structure.
3Reliability
If tie bars are partially or fully etched before encapsulation, then the wettable surface for soldering is enhanced, but additional processing steps are required
Solution Approach 1:
The etching of tie bars and the creation of wettable surfaces are combined into a single processing step. By etching the tie bars partially or fully before encapsulation, the process simultaneously creates separation paths and enhances solder adhesion surfaces, eliminating the need for separate wettable surface treatment steps.
Solution Approach 2:
The etching process is performed as a preliminary action before encapsulation, preparing both the separation paths and the soldering surfaces in advance. This preliminary preparation ensures that when the package is ready for assembly, the surfaces are already optimized for solder adhesion without requiring additional processing.
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 facilitates efficient singulation of leadframes with improved wettable surfaces, enhancing the reliability and efficiency of semiconductor package assembly by allowing for better solder adhesion and reducing the complexity of cutting paths, thus improving overall manufacturing processes.
Implementation Method 1
an electrically conductive layer is formed on the leadframe leads
Data Source
AI summary
Methods of forming a semiconductor package. Implementations include providing a leadframe, coupling a semiconductor die or an electronic component to the leadframe, and encapsulating at least a portion of the semiconductor die or the electronic component using a mold compound leaving two or more leads of the leadframe exposed. The method may also include coating the two or more leads of the leadframe with an electrically conductive layer. The method may include fully electrically and physically singulating one or more tie bars between two or more leads of the leadframe, a lead of the two or more leads and a leadframe flag, or any combination thereof. The method may also include singulating the leadframe to form one or more semiconductor packages.