Lead Frame Bridge Break Sealing via Molten Polymer Injection
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Solution Overview
Problem
Existing methods for breaking bridges in lead frames are susceptible to contamination, leading to unwanted electrical current flow and potential short circuits due to rebridging, which can damage the lead frame and other circuitry.
Innovation Solution
A method involving a bridge breaking tool with a collar and punch that forms and seals bridge breaks during the injection molding process, using molten polymer to encase and insulate the broken ends, preventing rebridging and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bridges are broken to prevent electrical current flow between circuits, then electrical isolation is achieved, but the broken ends become susceptible to contamination and rebridging
Solution Approach 1:
Molten polymer is introduced as an intermediary substance that fills the space around the broken bridge ends. As the polymer cures, it forms a protective seal that isolates the conductive ends from contaminants while maintaining the electrical isolation already achieved by the bridge break.
Solution Approach 2:
The cured polymer creates an inert environmental barrier around the bridge break ends. This protective environment prevents contaminants from accessing the conductive surfaces, thereby preventing rebridging while maintaining the electrical isolation function.
2Ease of manufacture
If bridge breaks are left exposed to allow easy inspection, then manufacturing simplicity is maintained, but short circuits can occur due to rebridging by contaminants
Solution Approach 1:
The bridge breaking operation and the sealing operation are merged into a single integrated process step. The bridge is broken and the polymer is injected in one continuous operation, eliminating the need for separate sealing steps while ensuring reliable contamination protection.
Solution Approach 2:
The polymer injection system automatically seals the bridge break ends as part of the normal molding process. The system self-services the sealing function without requiring additional manual intervention or complex separate operations, maintaining manufacturing simplicity while ensuring reliability.
3Object-affected harmful factors
If molten polymer is injected to seal bridge breaks, then contamination is prevented, but the molding process complexity increases
Solution Approach 1:
The polymer injection system performs multiple functions: it seals the bridge breaks to prevent contamination, provides structural support for the lead frame, and creates an insulating barrier. This multi-functionality reduces the need for separate dedicated sealing components or processes, thereby limiting the increase in overall system complexity.
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
Effectively seals and insulates bridge breaks, preventing short circuits and ensuring the integrity of the lead frame by encapsulating the broken ends within a hardened, insulated plastic material during the molding process.
Implementation Method 1
molten polymer flows around the bridge break and insulating the ends of the bridge break
Implementation Method 2
molten polymer is injected and flows around the ends of the bridge break... after the bridge break is encased in the cured molten polymer
Data Source
AI summary
A method is provided for the punching of a bridge break and thereafter sealing the bridge break during the injection molding process of the lead frame. The bridge breaking tool is placed over the bridge that is to be broken. The collar presses down on the circuit and the punch presses down on the bridge with enough force to form the bridge break. Once the bridge break is formed the punch is retracted from the cavity of the template and molten polymer is injected to flow around the ends of the bridge break. The bridge breaking tool's hold down collars and retracted punch form a molding area for molten polymer to flow over the bridge break and the exposed circuit area. The bridge breaking tool is retracted after the bridge break is encased in the cured molten polymer and the cured molten polymer forms a lead frame structure.