LED Lead Electrode Height Structure for Resin Burr Suppression
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Solution Overview
Problem
Conventional methods of manufacturing light emitting diodes (LEDs) often result in the generation of resin burrs due to the flow of resin into gaps between the lead frame and the mold, leading to bonding failures and requiring additional steps for burr removal.
Innovation Solution
The proposed solution involves a package design for mounting light emitting elements, which includes a recess with specific lead electrode configurations. The first lead electrode has a first region, a second region with a width of 110 μm or more and greater thickness, and a third region with smaller thickness. Similarly, the second lead electrode has a fourth region, a fifth region with a width of 110 μm or more and greater thickness, and a sixth region with smaller thickness. This design uses a mold with a projection that corresponds to the recess, preventing resin from entering and forming burrs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transfer molding is used to manufacture LEDs, then productivity is improved, but resin burrs are generated causing bonding failures
Solution Approach 1:
The patent applies preliminary action by forming a projection on the lead frame before the molding process. This projection pre-occupies the space where resin would otherwise flow and create burrs, preventing the harmful effect before it occurs. The projection is formed in advance and positioned to abut against the mold during molding, thereby preventing resin intrusion at critical locations.
Solution Approach 2:
The patent converts the harmful resin flow into a beneficial effect by allowing resin to fill the space around the projection. The projection that would normally be seen as an obstruction is instead used to control resin flow direction, guiding it away from critical bonding areas and toward safe zones, thereby converting a potential harm (resin intrusion) into a controlled flow pattern that prevents bonding failures.
2Manufacturing precision
If pressing force of the mold is increased to prevent resin burrs, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the burr prevention function from the mold structure itself and transfers it to the lead frame. Instead of making the mold more complex with additional features to control resin flow, the solution removes the need for such complex mold features by equipping the lead frame with a projection that performs the burr prevention function independently.
Solution Approach 2:
The projection on the lead frame acts as an intermediary element between the mold and the resin flow. Rather than directly modifying the mold structure to control resin flow, the projection serves as a mediator that intercepts and redirects resin flow, preventing it from reaching areas where it would create burrs.
3Manufacturing precision
If additional burr removal steps are added, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The patent applies preliminary anti-action by preventing burr formation in the first place through the projection on the lead frame. Instead of taking subsequent actions to remove burrs after they form, the projection proactively prevents resin from flowing into positions where burrs would be created, thereby eliminating the need for post-processing burr removal steps.
Data Source
AI summary
A package for mounting a light emitting element includes: a first lead electrode defining a portion of a bottom of a recess and comprising a base member and a plating disposed on the base member, and wherein the first lead electrode comprises, in a plan view: a first region, a second region surrounding a periphery of the first region, wherein, in a height direction, an upper surface of the base member in an entirety of the second region is higher than an upper surface of the base member in the first region, and a third region surrounding at least a portion of a periphery of the second region, wherein, in the height direction, an upper surface of the base member in the third region is lower than the upper surface of the base member in the entirety of the second region; a second lead electrode; and a resin molded body.