Lead Frame Layout to Reduce Moisture Intrusion in Packages
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electronic component packaging, the existing lead frame designs with exposed leads not used as terminals increase the risk of moisture intrusion into the package body due to additional exposed interfaces between leads and encapsulating resin.
Innovation Solution
A lead frame design with a die pad and a frame member including first and second connection bars, where the number of second leads is smaller than first leads, each second lead is connected to a corresponding first lead, reducing exposed interfaces and thus minimizing moisture intrusion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If leads not to be used as terminals are coupled to terminal leads in existing lead frame designs, then electrical connection is achieved, but the number of exposed leads increases and moisture intrusion risk increases
Solution Approach 1:
The patent extracts and removes the non-terminal leads from the exposed surfaces after encapsulation. Specifically, the non-terminal leads are cut off from the lead frame rim while maintaining electrical connection through the encapsulating resin, thereby eliminating unnecessary exposed interfaces that would allow moisture intrusion.
Solution Approach 2:
The patent merges the non-terminal leads with the encapsulating resin to maintain electrical connection while hiding the leads inside the package body. The encapsulating resin serves as both the encapsulation material and the electrical connection medium between the non-terminal leads and the terminal leads.
2Manufacturing precision
If entire surfaces of leads are plated to form good fillets, then soldering quality improves, but plating time and cost increase
Solution Approach 1:
The patent applies plating only to the necessary portions of the leads that require soldering connections. By selectively plating only the terminal leads and not the non-terminal leads, the plating time and cost are reduced while maintaining adequate soldering quality for the functional connections.
Data Source
AI summary
A lead frame includes a die pad, a plurality of leads, and a frame member. The frame member includes a first connection bar extending in a first direction and a second connection bar extending in a second direction. The die pad is connected to the second connection bar. The plurality of leads include a plurality of first leads connected to the first connection bar and a plurality of second leads connected to the second connection bar. The number of the plurality of second leads is smaller than the number of the plurality of first leads. Each of the plurality of second leads is connected to one corresponding first lead of the plurality of first leads.