Lead Frame Plating for LED Adhesion and Oxidation
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Solution Overview
Problem
Existing methods for manufacturing light emitting devices face challenges with adhesion between lead frames and resin parts due to poor adhesion between gold and the reflective resin, and difficulties in applying photoresist to corners and lateral surfaces of metal substrates.
Innovation Solution
A method involving a metal plate with pairs of metal parts, where a resist film is formed using electrodeposition on specific regions, and a gold or gold alloy plated layer is applied on other surfaces, ensuring precise placement and improved adhesion between the lead frame and resin molded body, while avoiding oxidation and sulfurization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entirety of outermost surfaces of lead frame is plated with gold, then oxidation resistance is improved, but adhesion between lead frame and reflective resin part deteriorates
Solution Approach 1:
The patent applies different plating treatments to different regions of the lead frame. Specifically, gold plating is applied only to the upper surface (light-emitting element mounting surface) where oxidation resistance is critical, while other surfaces such as the lower surface and side surfaces remain unplated or receive different plating to maintain adhesion with the resin molded body. This localized differentiation resolves the contradiction between oxidation resistance and adhesion strength.
2Manufacturing precision
If photoresist is applied to metal substrate, then patterning capability is improved, but coverage at corners and lateral surfaces deteriorates
Solution Approach 1:
The patent transitions from conventional photoresist application methods to electrodeposition, which adds a dimensional aspect by using electrical current distribution to control resist film formation. The electrodeposition process can uniformly deposit photoresist on complex three-dimensional surfaces including corners and lateral surfaces that are difficult to reach with conventional application methods, while maintaining precise patterning capability through mask alignment and controlled deposition parameters.
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 approach enhances adhesion between the lead frame and resin parts, reduces oxidation, and facilitates efficient formation of light emitting devices with improved connection strength and reduced leakage risks.
Implementation Method 1
disposing a mask of a resist film on the first region by using an electrodeposition technique
Implementation Method 2
using a plating technique to dispose a first plated layer containing gold or gold alloy on a second region
Data Source
AI summary
A method of manufacturing a light emitting device, including: providing a first structure including: providing a lead frame which includes providing a metal plate including a plurality of pairs of first and second metal parts, each metal part including an upper surface, a lower surface, and an end surface, the end surface of the first metal part and the end surface of the second metal part of each pair are opposite to each other, and a first region including the end surface, and disposing a mask of a resist film on the first region using an electrodeposition technique, disposing a first plated layer containing gold or gold alloy on a second region including the upper surface other than the first region on at least one of the upper surface, the lower surface, and the end surface of each of the first and second metal parts using a plating technique, and removing the resist film, providing a resin molded body molded integrally with the lead frame with parts of a lower surface of the lead frame being exposed, in which the first structure includes an upper surface defining a plurality of recesses each having an upward-facing surface, the first plated layer on the upper surface of the metal part is located at the upward-facing surface of each of the plurality of recesses; providing a second structure, the providing a second structure including; disposing at least one light-emitting element on the upward-facing surface each of the plurality of recesses, disposing a sealing member covering the at least one light-emitting element in each of the plurality of recesses; and separating the second structure into a plurality of discrete light emitting devices.