Light Emitting Device Recess Metal Layer Solder Containment
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Solution Overview
Problem
In light emitting devices with a resin layer on the electrode side, excessive solder squeezed out during mounting can cause bonding defects and reduce light extraction efficiency due to contamination of the light extraction surface.
Innovation Solution
A light emitting device with a semiconductor stacked-layer body and a resin member featuring a recess on its surface, where a metal layer is projected to surround the recess, effectively containing excessive adhesive and reducing solder overflow during mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a resin layer is disposed on the electrode side to support a bare chip, then sufficient mechanical strength can be reliably obtained, but excessive solder may be squeezed out during mounting causing bonding defects and contamination
Solution Approach 1:
The resin member is segmented by forming a recess that divides the upper surface into distinct regions: a light extraction region and a solder containment region. This segmentation allows the resin to simultaneously provide mechanical support while preventing solder from reaching the light extraction surface, thus resolving the contradiction between maintaining mechanical strength and preventing bonding defects
Solution Approach 2:
The recess acts as an intermediary structure between the solder and the light extraction surface. By providing this intermediate containment region, the recess intercepts and holds excessive solder, preventing it from contaminating the light extraction surface while maintaining the overall structural integrity provided by the resin layer
2Reliability
If solder is excessively supplied during mounting, then reliable electrical connection can be achieved, but solder may rise along the side surface of the resin layer causing bonding defects and contamination
Solution Approach 1:
The invention converts the harmful effect of excessive solder into a beneficial containment mechanism. The recess is specifically designed to receive and hold the excessive solder that would otherwise rise along the side surface and cause contamination. By providing this designated containment area, the harmful solder overflow is transformed into a controlled feature that does not affect bonding reliability or light extraction efficiency
3Area of moving object
If the light emitting device is miniaturized to CSP size, then the size is reduced almost to the size of the chip, but the space for adhesive containment is limited
Solution Approach 1:
Instead of increasing the planar area to provide solder containment space, the invention utilizes the vertical dimension by forming a recess into the resin member. This dimensional transition from 2D surface area to 3D volumetric containment allows the device to maintain its miniaturized CSP footprint while providing adequate space for adhesive containment within the limited volume
Data Source
AI summary
A light emitting device includes a semiconductor light emitting element including a semiconductor stacked-layer body and an electrode disposed on a first surface of the semiconductor stacked-layer body; a resin member disposed on a first surface side of the semiconductor stacked-layer body; and a metal layer disposed in the resin member and electrically connected to the electrode. A recess is defined in an upper surface of the resin member. The metal layer is projected from the upper surface of the resin member, and is disposed to surround at least a portion of the recess.