Lead Recesses for Stronger Light Emitting Device Bonding
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Solution Overview
Problem
Conventional flip chip mounting packages for light emitting elements face challenges in achieving strong bonding between leads, which can lead to reduced reliability and performance due to inadequate bonding strength.
Innovation Solution
The package design incorporates a first lead with a recess or through hole and a second lead with overlapping recess or through holes, allowing for increased bonding area with a molded body that fills these features, enhancing the bonding strength between the leads through direct bonding or use of adhesives/solder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If two leads are bonded by resin, solder, or the like in conventional packages, then the bonding process is simple, but the bonding strength between leads is insufficient
Solution Approach 1:
The lead structure is segmented into multiple portions (first portion, second portion, third portion) with recess portions created at specific locations. This segmentation allows the molded body to interlock with the leads through the recess portions, creating mechanical engagement that significantly enhances bonding strength between stacked leads while maintaining a manageable structural complexity through systematic design.
2Reliability
If leads are bonded using conventional methods, then the manufacturing process is straightforward, but the reliability of the light emitting device is reduced
Solution Approach 1:
The recess portions are preliminarily formed in the lead portions before the bonding process. This preliminary action creates pre-defined engagement features that guide the molded body placement and ensure proper alignment during assembly. The pre-formed recess portions enable more reliable bonding while maintaining manufacturing ease through standardized formation processes such as etching or molding.
3Strength
If the bonding area between leads is increased, then the bonding strength is improved, but the device structure becomes more complex
Solution Approach 1:
The bonding interface is extended from a simple planar surface to a three-dimensional interlocking structure through vertically extending recess portions. This dimensional change allows the molded body to engage with the leads not only at the surface level but also through the depth of the recess portions, effectively increasing the bonding area and strength while maintaining a compact overall structure that does not significantly increase the device footprint.
Data Source
AI summary
A package includes a first lead, a first molded body, a second lead, and a second molded body. The first lead includes a first portion which has a first recess portion or a first through hole passing through the first portion. The second lead is provided on the first lead to be bonded to the first lead such that a bonding side surface faces to the first lead. The second lead includes a second portion which overlaps with the first portion and which has a second recess portion on the bonding side surface or a second through hole passing through the second portion. The second recess portion communicates with the first through hole. The second through hole communicates with the first recess portion. The second molded body fills the first through hole and the second recess portion, or fills the first recess portion and the second through hole.