Submount Bondpad Layout for LED Light Mixing
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Solution Overview
Problem
Existing semiconductor light emitting device packages are inadequate for mounting multiple LEDs closely together to achieve desired intensity and color of light, particularly in general lighting applications where LEDs emitting in different regions of the visible spectrum are required.
Innovation Solution
A package design featuring a submount with strategically positioned electrical bondpads and a reflector cup to allow for close mounting of LEDs, using thermally conductive and electrically insulating materials like SiC and AlN, and a solderable metal layer, with wirebond connections to external leads for efficient light emission and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple LEDs are mounted closely together in existing packages, then light intensity and color consistency are improved, but wirebond complexity and assembly difficulty increase
Solution Approach 1:
The patent divides the electrical connection system into multiple independent bondpads (first bondpad, second bondpad, third bondpad) distributed across the submount. Each bondpad independently connects to LED chips, allowing close mounting without complex wirebond routing. The bondpads are positioned at different locations (first bondpad near first side surface, second bondpad near second side surface, third bondpad between second side surface and die mounting region) to simplify interconnections.
Solution Approach 2:
The submount acts as an intermediary component between the LED chips and external leads. It provides a platform with multiple bondpads that simplify the electrical interconnection network, reducing wirebond complexity while enabling close LED mounting for improved light mixing and color consistency.
2Stability of the object's composition
If multiple LEDs are mounted closely together, then color consistency and light mixing are enhanced, but available mounting area and heat dissipation space are reduced
Solution Approach 1:
The patent utilizes the vertical dimension and perimeter areas of the submount by positioning bondpads at different locations including near the first side surface, second side surface, and extending toward the second side surface. This distributed arrangement maximizes the use of available submount area, enabling close LED mounting for improved color consistency while maintaining adequate space for heat dissipation.
3Stability of the object's composition
If bondpads are positioned to allow close LED mounting, then light mixing improves, but electrical isolation and signal integrity may be compromised
Solution Approach 1:
The patent assigns different functional qualities to different bondpad locations: the first bondpad (near first side surface) and second bondpad (near second side surface) provide electrical connections, while the third bondpad (between second side surface and die mounting region) provides additional connection points. This localized functional assignment ensures proper electrical isolation and signal integrity while enabling close LED mounting for improved light mixing.
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
Enables improved light mixing and uniform emission by allowing multiple LEDs to be mounted closely, enhancing light intensity and color consistency, while simplifying assembly and improving reliability through reduced wirebond complexity and independent control of LED chips.
Implementation Method 1
The support member may include a thermally conductive, electrically insulating material. In particular embodiments, the support member may include SiC, AlN and/or diamond.
Implementation Method 2
a metallised layer having light-reflectivity
Data Source
Figure 1~2
Figure 3~4
AI summary
A submount (14) for a solid state lighting package (50) includes a support member having upper and lower surfaces, a first side surface, and a second side surface opposite the first side surface, a first electrical bondpad on the upper surface of the support member and having a first bonding region proximate the first side surface of the support member and a second bonding region extending toward the second side surface of the support member, and a second electrical bondpad on the upper surface of the support member having a die mounting region proximate the first side surface of the support member and an extension region extending toward the second side surface of the support member. The die mounting region of the second electrical bondpad may be configured to receive an electronic device. The submount further includes a third electrical bondpad on the upper surface of the support member and positioned between the second side surface of the support member and the die mounting region of the second electrical bondpad.