Light Emitting Device Package with Solder Grooves for Inspection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light emitting device packages with quad flat no-lead (QFN) lead frames lack a method for inspecting the quality and completeness of solder joints for electrical connections to external components, which affects packaging density and reliability.
Innovation Solution
A light emitting device package design featuring a leadframe unit with exposed top and bottom surfaces, a molding layer that encloses the leadframe and includes solder grooves, allowing visual inspection of solder joints, and an optional electro-plating layer for enhanced adhesion and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional QFN lead frame with solder joints on the bottom surface is used to increase packaging density and decrease packaging size, then the packaging density and packaging size are improved, but the ability to inspect solder joint quality and electrical connection completeness deteriorates
Solution Approach 1:
The patent transitions the solder joints from a completely hidden bottom-surface configuration to a multi-dimensional arrangement where solder grooves extend from the bottom surface upward through the molding layer. This dimensional change allows solder joints to be accessible for inspection from the top surface while maintaining the compact QFN package structure, thereby resolving the contradiction between high packaging density and inspectability.
Solution Approach 2:
The patent introduces the molding layer as an intermediary structure that contains integrated solder grooves. This intermediary design allows the solder joints to be both concealed within the package (maintaining compactness) and accessible through the groove openings (enabling inspection), thus mediating between the conflicting requirements of small package size and solder joint inspectability.
2Reliability
If solder joints are completely enclosed within the molding layer to protect them, then the reliability is improved, but the ability to visually inspect solder joint quality deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the enclosure structure: the molding layer encloses the leadframe unit for protection, but specifically creates openings (solder grooves) at the locations where solder joints need to be accessible. This localized modification allows simultaneous achievement of protection (through enclosure) and inspectability (through strategic openings).
Solution Approach 2:
The patent utilizes optical contrast (analogous to color changes) by making the solder grooves visually distinct through their geometric structure and positioning, allowing the solder joints within them to be easily distinguished and inspected against the surrounding molding layer material.
Data Source
AI summary
Alight emitting device package includes a leadframe unit, a molding layer, and a light emitting device. The leadframe unit has opposite leadframe top and bottom surfaces. The molding layer encloses the leadframe unit, and has a molding-layer bottom surface, a molding-layer surrounding surface extending upward from the molding-layer bottom surface to surround the leadframe unit, and a plurality of solder grooves indented from the molding-layer bottom surface. Each of the solder grooves has one end meeting the leadframe unit and another end opening at the molding-layer surrounding surface. The light emitting device is disposed on the leadframe top surface of the leadframe unit.