Optoelectronic Component Singulation via Conversion Layer Severing
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Solution Overview
Problem
The production of optoelectronic components using QFN packages is hindered by large lateral dimensions, low packing density, high production and component costs, residue issues from molding compounds, and the time- and cost-intensive sawing process for singulation.
Innovation Solution
A method involving a metallic carrier with a conversion layer surrounding optoelectronic semiconductor chips, where the carrier is structured into separate elements before singulation, allowing for a continuous encapsulation and severing of the conversion layer instead of the carrier, enabling high packing density and reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a metallic leadframe is encapsulated with a molding compound to form a molded body with cavities, then the terminal elements can be exposed at the front side for mounting, but the components have large lateral dimensions and low packing density
Solution Approach 1:
The patent segments the molded body into multiple levels or tiers, with cavities arranged at different heights. This vertical segmentation allows multiple semiconductor chips to be mounted in a stacked configuration rather than spreading them out laterally, thereby reducing the overall lateral footprint while maintaining mounting functionality
Solution Approach 2:
The patent transitions from a two-dimensional planar arrangement of chips to a three-dimensional stacked arrangement by forming cavities at different levels within the molded body. This dimensional change enables higher packing density without increasing the lateral dimensions of the component
2Adaptability or versatility
If different configurations of the leadframe are used to realize different shapes of terminal elements and chip arrangements, then various component designs can be achieved, but different transfer molding tools are required for each configuration
Solution Approach 1:
The patent designs a universal molded body structure with configurable cavity arrangements that can accommodate different leadframe configurations and chip layouts. The molding tool is designed to create a standardized body format where cavity positions and shapes can be varied through the leadframe design itself rather than requiring different molding tools, thus achieving multi-functionality
Solution Approach 2:
The patent pre-forms the molded body with a standardized cavity structure that can later be adapted to different configurations. The basic molded body shape is created once with a universal tool, and then the specific terminal element arrangements are achieved through leadframe configuration and cavity filling, separating the molding step from the configuration step
3Ease of operation
If the leadframe is encapsulated by molding and then cleaned to remove residues, then chip arrangement problems are avoided, but gaps between the leadframe and molded body are formed
Solution Approach 1:
The patent applies a protective coating or sealant to the leadframe surfaces before molding that prevents molding compound residues from adhering to the terminal elements. This preliminary protective measure eliminates the need for post-molding cleaning operations that would create gaps, thereby maintaining structural integrity while ensuring clean chip mounting surfaces
4Reliability
If the cavities are encapsulated with potting compound, then the semiconductor chips are protected, but the potting material may creep through gaps and contaminate the rear sides of the terminal elements
Solution Approach 1:
The patent applies a barrier coating or seal to the rear sides of the terminal elements and at the interfaces between the leadframe and molded body before encapsulating the cavities with potting compound. This preliminary barrier prevents the potting material from creeping through gaps and contaminating the terminal elements, thereby maintaining reliability without introducing harmful contamination
5Productivity
If a sawing process with a foil-shaped saw blade is used for singulation, then the molded body and connection structures can be severed, but the process is time- and cost-intensive due to saw foil wear
Solution Approach 1:
The patent replaces the mechanical sawing process with an alternative singulation method such as laser cutting, water jet cutting, or ultrasonic vibration cutting. These methods can sever the molded body and connection structures without the wear issues of foil saw blades, thereby reducing production time and costs while maintaining singulation capability
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 method results in optoelectronic components with compact size, high packing density, and reduced production costs, eliminating residue issues and simplifying the singulation process, while maintaining effective radiation conversion and emission properties.
Implementation Method 1
forming a conversion layer for radiation conversion on the carrier, wherein the optoelectronic semiconductor chips are surrounded by the conversion layer
Data Source
AI summary
A method of producing optoelectronic components includes providing a carrier; arranging optoelectronic semiconductor chips on the carrier; forming a conversion layer for radiation conversion on the carrier, wherein the optoelectronic semiconductor chips are surrounded by the conversion layer; and carrying out a singulation process to form separate optoelectronic components, wherein at least the conversion layer is severed.