LED Die on Leadframe with Embedded Holding Elements
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Solution Overview
Problem
Existing lighting devices with packaged LED elements face challenges such as impaired thermal contact, increased costs, and reduced design flexibility due to packaging, and direct attachment of unpackaged LED die elements to leadframes can be complex and risk optical functionality impairment.
Innovation Solution
A lighting device with spaced apart LED light sources on a leadframe, where unpackaged LED die elements are directly attached to conductor segments, and holding elements are used to stabilize and fix the conductor segments without covering the LED die elements, allowing for flexible design and improved thermal dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If packaged LED elements (L1 LEDs) are used, then ease of handling and integration is improved, but thermal contact between LED die element and leadframe is impaired
Solution Approach 1:
The patent extracts the LED die element from its package housing, allowing direct attachment to the leadframe. This removes the packaging layer that would otherwise impede thermal contact, while the leadframe itself provides the necessary mechanical support and electrical connection.
Solution Approach 2:
The LED die element is nested directly within the leadframe structure, with the die attached to conductor segments that are embedded in holding elements. This nested arrangement ensures intimate thermal and electrical contact between the LED die and the leadframe without requiring separate packaging.
2Ease of operation
If packaged LED elements (L1 LEDs) are used, then ease of handling is improved, but manufacturing cost increases
Solution Approach 1:
The patent eliminates the packaging step by extracting the LED die from its housing and attaching it directly to the leadframe. This removes the cost of packaging materials and the manufacturing steps required to assemble packaged LEDs, while maintaining ease of handling through the integrated leadframe structure.
3Ease of operation
If packaged LED elements are used, then handling is simplified, but design flexibility is reduced
Solution Approach 1:
By extracting the LED die from standardized packaging, the patent enables custom positioning and orientation directly on the leadframe. This allows designers to optimize the optical and thermal performance for specific applications rather than being constrained by packaged LED form factors.
Solution Approach 2:
The patent applies different properties to different parts of the leadframe structure, with holding elements providing mechanical support in some areas while leaving other areas open for optimal optical performance. This localized differentiation enables both handling stability and design flexibility.
4Temperature
If unpackaged LED die elements are directly attached to leadframe, then thermal contact is improved, but production process complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-forming the leadframe with embedded holding elements that have cavities ready to receive the LED die. This preliminary preparation of the mounting structure simplifies the subsequent die attachment process, making it more straightforward than direct attachment to a plain leadframe.
Solution Approach 2:
The holding elements act as intermediaries between the LED die and the leadframe. These elements provide a simplified interface for attachment while ensuring proper positioning, mechanical support, and electrical connection, thereby reducing the overall complexity of the production process.
5Ease of manufacture
If conductor segments are not fixed relative to each other, then manufacturing flexibility is improved, but attachment reliability decreases
Solution Approach 1:
The leadframe is pre-formed with holding elements that have cavities designed to receive and secure the LED die. This preliminary structuring ensures that when the die is attached, it is automatically positioned and secured in a reliable manner, eliminating the need for additional fixing steps.
Solution Approach 2:
The holding elements serve as intermediaries that provide both mechanical support and electrical connection. By embedding conductor segments within these holding elements, the patent ensures reliable electrical contact and mechanical stability without requiring the conductor segments to be rigidly fixed to each other.
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 solution enables a cost-effective, flexible, and thermally efficient lighting device with improved handling and integration capabilities, maintaining optical flexibility and reducing manufacturing complexity while ensuring stable electrical connections.
Implementation Method 1
LED light sources comprise an LED chip, which is here referred to as an LED die, as the actual light emitting component. For semiconductor LEDs, the die generally is a chip of doped semiconducting material which includes a p/n junction.
Implementation Method 2
A leadframe comprises a plurality of (i. e. at least two, usually more than two) conductor segments
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5d
AI summary
The invention relates to a lighting device (10) and a manufacturing method especially therefor. LEDs (12a, 12b, 12c) are arranged at a distance from each other. A leadframe (20) comprising conductor segments is provided interconnecting the LEDs (12a, 12b, 12c). The LEDs (12a, 12b, 12c) each comprise an LED die (30) attached to one of the conductor segments of the leadframe (20). The LEDs (12a, 12b, 12c) further each comprise a holding element (22) disposed to hold at least two conductor segments of the leadframe (20) which are at least partially embedded within the holding element (22). In order to obtain good optical properties, the holding elements (22) do not cover the LED dies (30). In addition, one or more of the conductor segments of the leadframe (20) are configured to be bent such that the lighting device (10) may be shaped. According to the proposed manufacturing method of the lighting device (10), conductor segments of the leadframe (20) are provided and holding elements (22) are formed at a distance from each other on the leadframe (20), each at least partially embedding at least two conductor segments of the leadframe (20). Mounting portions (26) of at least three conductor segments of the leadframe (20) are not covered by the holding elements (22). LED dies (30) are attached to the mounting portions (26).