Tapered Cap Sidewall Routing for Optoelectronic Interconnections
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Solution Overview
Problem
Optoelectronic devices in the thermal infrared (TIR) and long wavelength infrared (LWIR) regions face challenges in efficiently routing electrical interconnections due to the need for substantial space between bond pads and the edge of the cap, which complicates access to electrical connections and increases packaging complexity.
Innovation Solution
The use of tapered caps and substrates with angled sidewalls allows for the routing of electrical interconnections along the substrate, enabling miniaturization and reduced costs by exposing bonding platforms and allowing for single dicing operations, while maintaining transparency for light and providing secure electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cap with vertical walls is used to seal and protect optoelectronic elements, then sealing and protection are improved, but substantial space margin is required between bond pads and cap edge, increasing packaging complexity and reducing accessibility to electrical connections
Solution Approach 1:
The cap transitions from vertical walls to tapered sidewalls with angles between 10-75 degrees, creating an asymmetric profile that exposes bonding platforms and reduces the space margin requirement between bond pads and cap edge, thereby simplifying packaging while maintaining sealing integrity
Solution Approach 2:
The electrical connections are routed along the tapered sidewall surface of the cap rather than requiring horizontal clearance, utilizing the vertical dimension created by the tapered profile to provide access to bonding platforms without increasing lateral packaging space
2Ease of operation
If substantial space margin is maintained between bond pads and cap edge for access to electrical connections, then electrical connection accessibility is improved, but packaging area and device footprint increase
Solution Approach 1:
Electrical connections are routed along the tapered sidewall surface, utilizing the vertical and slanted surfaces of the cap rather than requiring additional horizontal space, thereby maintaining connection accessibility while reducing overall packaging footprint
Solution Approach 2:
The tapered profile creates exposed bonding platforms on the slanted surface, allowing electrical connections to be accessed from the side rather than requiring horizontal clearance, thus maintaining accessibility while reducing packaging area
3Manufacturing precision
If multiple dicing operations are performed to create caps with vertical walls and expose bonding platforms, then precise cap formation is achieved, but manufacturing complexity and production time increase
Solution Approach 1:
The cap is formed with tapered sidewalls and exposed bonding platforms in a single dicing operation rather than requiring multiple steps, as the tapered profile inherently provides the necessary platform exposure during the dicing process itself
Solution Approach 2:
The cap formation and bonding platform exposure operations are merged into a single dicing step, where the tapered sidewall geometry allows both functions to be achieved simultaneously, reducing manufacturing steps and increasing productivity
Data Source
AI summary
An optoelectronic device package includes an optoelectronic device having an active region on a first surface of a substrate, a bond pad area on the first surface that includes at least one contact pad electrically connected to the active region, and a cap having a first cap surface and a second cap surface, the first cap surface being secured to the first surface of the substrate, the cap covering the optoelectronic device. At least one of the cap and the substrate has an angled sidewall extending at an angle relative to an axis parallel to an optical path. The at least one contact pad is exposed by and adjacent to the angled sidewall. An electrical line extends from each of the at least one contact pad along the angled sidewall and to the second cap surface that does not overlap the active region.