Lead Frame Assembly Layout to Limit Pin Exposure and Moisture
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Solution Overview
Problem
The existing lead frame assemblies for chip packaging devices face issues with moisture ingress due to the exposure of a large number of pins, which can damage the light-emitting diode and reduce the reliability of the device.
Innovation Solution
A lead frame assembly with a frame and an array of lead frame units, each comprising a chip holder with independent electrode pads and a pin unit with strategically positioned pins. The pin unit extends from the chip holder, with only specific pins exposed through connecting peripheral surfaces, reducing moisture ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a greater number of pins are exposed outwardly from the reflector cup, then the electrical connection and signal transmission are improved, but moisture can easily enter through interfaces between pins and reflector cup, causing light-emitting diode damage and reducing reliability
Solution Approach 1:
The patent extracts the harmful interface between pins and reflector cup by removing the reflector cup structure. Instead of having pins embedded in the reflector cup with exposed interfaces, the lead frame units are directly embedded in the encapsulant, eliminating the pin-reflector cup interface that serves as a moisture ingress pathway while maintaining necessary electrical connections
Solution Approach 2:
The patent uses the encapsulant as a flexible sealing shell that completely encloses the lead frame units, replacing the rigid reflector cup structure. The encapsulant forms a continuous protective barrier around all pins and lead frame components, preventing moisture from reaching pin interfaces while allowing the necessary electrical and optical functions to operate
2Ease of operation
If multiple pins are exposed for electrical connection, then the electrical connectivity is improved, but the complexity of the device structure increases
Solution Approach 1:
The patent merges the pin functions into integrated lead frame units where multiple electrical connection points are combined into a single embedded structure. The lead frame units integrate multiple electrode carriers and pins into unified components that are collectively embedded in the encapsulant, reducing the number of separate interface structures while maintaining all necessary electrical connections
Data Source
AI summary
Disclosed herein is a lead frame assembly including a frame and lead frame units each including a chip holder having first and second electrode pads; and a pin unit having a first pin, a second pin and third pins each extending from the chip holder. The pin unit extending from one of the lead frame units is connected to the pin unit of the adjacent one of the lead frame units. For the lead frame units disposed adjacent to the frame, the pin units extending towards the frame are connected to the frame such that the lead frame units are fixedly positioned within the frame. A chip packaging device including a lead frame body and a packaging structure is also disclosed.