Optoelectronic Leadframe with Segmented Pedestal for Adhesive Creep Control
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Solution Overview
Problem
Existing optoelectronic components face challenges in assembly and light extraction due to adhesive bonding, particularly when using radiation-emitting semiconductor chips, as adhesives can creep onto the chip's side surfaces, reducing light extraction efficiency and potentially degrading the leadframe material.
Innovation Solution
A leadframe design featuring a single pedestal support surface smaller than the semiconductor chip's mounting surface, with a reflective casting compound that does not cover the chip, and a method for producing optoelectronic components using a leadframe with a self-supporting structure, preventing adhesive creep and enhancing light extraction while maintaining thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive bonding is used to assemble the semiconductor chip to the leadframe, then the chip can be securely mounted, but adhesive can creep onto the chip's side surfaces, reducing light extraction efficiency
Solution Approach 1:
The leadframe is divided into functionally distinct elements: a mounting element for secure chip attachment, a support element with a precisely controlled support surface, and a barrier element. This segmentation allows the support surface to be smaller than the chip's side surface area, creating a physical barrier that prevents adhesive creep onto light-emitting surfaces while maintaining secure mounting through the dedicated mounting element.
Solution Approach 2:
The support surface of the support element is designed with specific local properties: it has a smaller area than the chip's side surface area, creating a localized barrier zone. This local quality control ensures that adhesive remains confined to the support surface during bonding, while the larger chip side surfaces remain exposed for optimal light extraction.
2Strength
If adhesive is applied to bond the chip, then secure mounting is achieved, but the leadframe material may degrade due to adhesive exposure
Solution Approach 1:
The support surface is extracted as a distinct functional zone with controlled dimensions, separated from the main leadframe body. By making the support surface smaller than the chip's side surface area, the adhesive is confined to this extracted zone, preventing contact with and degradation of the broader leadframe structure, thus preserving leadframe longevity while maintaining bonding strength.
Solution Approach 2:
The support element acts as an intermediary between the chip and the leadframe body. It provides a controlled interface for adhesive bonding while protecting the main leadframe structure from direct adhesive exposure, thereby preventing degradation and extending component life.
3Stability of the object's composition
If the support surface is made larger to fully support the chip, then mechanical stability improves, but adhesive can spread more easily onto the chip's side surfaces
Solution Approach 1:
The leadframe is segmented into a dedicated mounting element for mechanical stability and a support element with a smaller, controlled support surface. This segmentation allows the mounting element to provide sufficient mechanical stability while the smaller support surface prevents adhesive spread onto light-emitting chip surfaces.
Solution Approach 2:
The support surface is designed with specific local quality characteristics: its area is deliberately made smaller than the chip's side surface area. This local quality control creates a barrier that limits adhesive spread while the mounting element provides the necessary mechanical stability through its structural design.
Data Source
AI summary
An optoelectronic component having a leadframe and a method for producing an optoelectronic component are disclosed. In an embodiment, an optoelectronic component includes a radiation-emitting semiconductor chip having a mounting surface and side surfaces, a leadframe comprising a first element having a first main extension plane, a second element having a second main extension plane, and a third element having a third main extension plane, wherein the main extension planes are arranged parallel to one another, and wherein the elements are arranged one above the other in a stacking direction; and a reflective casting compound forming a planar surface facing the mounting surface of the semiconductor chip, wherein the semiconductor chip is mounted with the mounting surface on a support surface of the third element, which is smaller than the mounting surface of the semiconductor chip, such that the semiconductor chip projects laterally beyond the support surface of the third element.