Optical Subassembly Layout for Compact High-Frequency Signal Paths
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Solution Overview
Problem
Current TO-CAN-type optical subassemblies face challenges in achieving high-frequency characteristics and compactness while maintaining operational reliability in a wide temperature range, especially in harsh industrial environments, due to restricted mounting areas and difficulties in grounding the substrate, which limits their manufacturing efficiency and cost-effectiveness.
Innovation Solution
The optical subassembly design includes an eyelet with through-holes for lead terminals, a relay substrate with conductor patterns connected to the lead terminals, a device mounting unit for the optical device, and a temperature adjustment device, with bonding wires and a subcarrier to improve signal transmission and thermal management, allowing for differential signal propagation and efficient component arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the mounting area is reduced to achieve compactness, then the device size is reduced, but the high-frequency characteristics deteriorate due to restricted component arrangement and grounding difficulties
Solution Approach 1:
The patent utilizes the vertical dimension by forming conductor patterns on both the front surface and back surface of the mounting substrate. This three-dimensional conductor arrangement allows signal transmission paths to extend in the thickness direction, effectively increasing the available mounting area without increasing the planar footprint, thereby maintaining compactness while improving high-frequency characteristics.
Solution Approach 2:
The mounting substrate serves multiple functions: it provides mechanical support for mounting the optical device, establishes electrical ground connections through conductive patterns on both surfaces, and enables signal transmission via the conductor patterns. This multi-functionality allows the substrate to address both compactness and high-frequency performance requirements simultaneously.
2Reliability
If the eyelet diameter is changed to improve signal transmission, then the high-frequency characteristics are improved, but the manufacturing cost increases due to the need for new manufacturing apparatus
Solution Approach 1:
The patent optimizes the existing eyelet diameter parameters and conductor pattern dimensions to achieve improved high-frequency characteristics without changing the eyelet size. By adjusting conductor pattern geometry, thickness, and arrangement, the invention maintains compatibility with existing manufacturing apparatus while achieving better signal transmission performance.
3Reliability
If the conductor pattern area is increased to improve signal transmission, then the high-frequency characteristics are improved, but the mounting area for other components is reduced
Solution Approach 1:
The conductor patterns are arranged to utilize the thickness direction of the mounting substrate, with conductive patterns formed on both the front and back surfaces. This vertical arrangement allows extensive conductor pattern area for signal transmission without occupying additional planar mounting space, resolving the contradiction between signal transmission area and component mounting area.
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 characteristics, facilitates easy manufacturing, and maintains satisfactory performance across a wide temperature range, addressing the limitations of existing TO-CAN-type optical subassemblies by optimizing signal transmission and thermal management.
Implementation Method 1
bonding wires, respectively, and wherein the first bonding surface and the second bonding surface have normal directions in the same direction
Implementation Method 2
a temperature adjustment device, with bonding wires and a subcarrier to improve signal transmission and thermal management
Data Source
AI summary
Provided is an optical subassembly, which is compact, is easy to manufacture, and has satisfactory high-frequency characteristics. The optical subassembly includes: an eyelet including a first surface, a second surface and a plurality of through-holes; a plurality of lead terminals; a relay substrate including a lead connection surface and a first bonding surface and having first and second conductor patterns formed across the lead connection surface and the first bonding surface; a device mounting unit including a second bonding surface having formed thereon third and fourth conductor patterns; and an optical device configured to convert one of an optical signal and the differential electrical signals into the other. The first and second conductor patterns on the first bonding surface are connected to the third and fourth conductor patterns by bonding wires, respectively, and the first and second bonding surfaces have normal directions in the same direction.