Lead Frame Non-Terminal Lead Removal for Moisture Protection
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Solution Overview
Problem
In existing lead frames for electronic components, such as Dual Flatpack No-leaded (DFN) packages, the exposure of non-terminal leads increases the risk of moisture intrusion due to the larger surface area, which can lead to reliability issues and potential failure.
Innovation Solution
A lead frame design that includes specific leads connected to a second connection bar via wires, where the wires are directly connected to the second connection bar and can be plated with materials like Au, Ag, Cu, or Pd-PPF, reducing the exposed surface area by being partially removed during manufacturing, thereby minimizing moisture intrusion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If leads are extended to connect to the lead frame rim, then electrical connection is improved, but the exposed surface area increases and moisture intrusion risk increases
Solution Approach 1:
The patent extracts the non-terminal leads from the lead frame rim structure by cutting them after encapsulation. This removes the harmful exposed surfaces of non-terminal leads while preserving the electrical connection function through the remaining terminal leads that are properly plated.
Solution Approach 2:
The patent segments the leads into terminal leads (which remain connected to the lead frame rim and are plated) and non-terminal leads (which are cut off after encapsulation). This segmentation allows differential treatment: terminal leads maintain electrical connection while non-terminal leads are removed to eliminate moisture intrusion paths.
2Manufacturing precision
If the entire surfaces of leads are plated, then soldering quality is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies plating only to the terminal leads that require electrical connection and soldering, rather than plating all leads. This local quality approach ensures high soldering quality where needed while avoiding unnecessary plating on non-terminal leads that are subsequently removed.
Solution Approach 2:
The patent performs preliminary plating on the terminal leads before encapsulation, when the leads are still accessible and can be easily plated. This preliminary action ensures proper soldering quality is achieved before the leads are embedded in the encapsulant.
3Object-affected harmful factors
If non-terminal leads are removed after encapsulation, then moisture intrusion risk is reduced, but the number of manufacturing steps increases
Solution Approach 1:
The patent merges the lead removal step with the encapsulation process by performing both operations in sequence without intermediate handling. The leads are cut off immediately after encapsulation in a single manufacturing flow, which minimizes the number of discrete steps while achieving the moisture protection benefit.
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
The design effectively reduces the risk of moisture intrusion into the package body by minimizing the exposed surface area of non-terminal leads, enhancing the reliability of the electronic component and reducing wear on manufacturing tools.
Implementation Method 1
the at least one wire may be directly connected to the second connection bar. In such a case, the second connection bar may be plated with Au, Ag, Cu, Ni, or Pd-PPF
Data Source
AI summary
A lead frame includes a die pad, a plurality of leads, a frame member, and at least one wire. The frame member includes two first connection bars and two second connection bars. The plurality of leads include a plurality of specific leads. Each of the specific leads is connected to the first connection bar. At least one of the specific leads is connected to the second connection bar via the at least one wire.