Optical Subassembly Ceramic Support Block Metallization
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Solution Overview
Problem
Current optical subassemblies face challenges in balancing high-frequency characteristics and downsizing, particularly in TO-CAN package type modules, which have limited heat dissipation and operable temperature range, making them unsuitable for high-speed and low-cost optical communication requirements over a wide temperature range.
Innovation Solution
The optical subassembly design includes a ceramic support block with a metallization pattern connected to a metal pedestal and lead pins, allowing for improved heat dissipation and high-frequency performance, while maintaining a compact size through precise positioning of components and use of materials like aluminum nitride for thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metallic carrier is wire-bonded to a metallic pedestal to improve high frequency characteristics, then high frequency characteristics are improved, but device size increases and downsizing becomes difficult
Solution Approach 1:
The patent merges the metallic carrier and pedestal into a single integrated metallic stem structure. The stem includes an eyelet at one end and a pedestal at the other, eliminating the need for separate components and wire bonding. This integration maintains high frequency characteristics through continuous metallic conductivity while reducing device size by removing the wire bonding layer and associated spacing.
Solution Approach 2:
The patent extracts the wire bonding function from the structure and replaces it with direct electrical connection through the integrated stem. By taking out the wire bonding step, the design achieves both size reduction and maintained electrical performance, as the metallic stem provides direct conductive paths without the parasitic inductance of wire bonds.
2Reliability
If a Peltier cooling device is used with an EML light source to control temperature, then temperature stability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the Peltier cooling device from the system and operates the EML light source without active temperature control. The design accepts temperature variations within the industrial range (-40 to 85°C) and optimizes the optical structure to maintain performance without the complexity of cooling hardware.
Solution Approach 2:
The patent implements self-service by designing the optical subassembly to operate autonomously without external temperature control. The EML light source and optical elements are configured to function directly across the industrial temperature range, eliminating the need for Peltier devices and associated control systems.
3Volume of moving object
If TO-CAN package type optical subassembly is used for compact size, then device size is reduced, but heat dissipation performance deteriorates
Solution Approach 1:
The patent applies local quality by creating thermal pathways only in specific locations where heat generation occurs. The metallic stem provides thermal conduction along its length, and the support block with metallization pattern creates localized thermal paths from the optical element to the metallic stem. This targeted approach maintains compact TO-CAN packaging while improving heat dissipation at critical hot spots.
Solution Approach 2:
The patent uses composite materials combining metallic and ceramic components. The metallic stem provides thermal conduction and mechanical support, while the ceramic support block provides electrical insulation and structural stability. This composite structure achieves both compact packaging and improved thermal management by leveraging the complementary properties of different materials.
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
This configuration enhances high-frequency transmission characteristics and extends the operable temperature range, meeting the demands for low-cost, high-speed optical communication over a wide temperature range, including the industrial temperature range of -40 to 85°C.
Implementation Method 1
an optical element for converting an optical signal and an electric signal at least from one to another
Implementation Method 2
The support block has a metallization pattern that is electrically connected to the pedestal
Implementation Method 3
use of materials like aluminum nitride for thermal conductivity
Data Source
AI summary
An optical subassembly includes: a support block made of ceramic in front of the first surface, the support block having a substrate mounting surface, the support block having a first side opposite to a surface in front of the first surface; an element-mounted substrate on the substrate mounting surface, the element-mounted substrate having a first conductor pattern; a pedestal made of metal and configured to be the same potential as the eyelet, the pedestal situated in front of the first surface; and a lead pin in the through-hole and for transmitting the electric signal. The support block has a metallization pattern that is electrically connected to the pedestal and is continuous from at least a part of the substrate mounting surface to at least a part of the first side.