Optical Device Flexible Substrate Orthogonal Wiring Thermal Dissipation
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Solution Overview
Problem
Conventional optical devices face challenges in achieving high thermal dissipation, miniaturization, and increased pin density due to low thermal conductivity and narrow width constraints, leading to reliability issues and solder bridge formation during mounting.
Innovation Solution
The optical device employs a bendable flexible substrate on a metallic frame with internal and external wiring terminals arranged orthogonally, utilizing high thermal conductivity metal for efficient heat dissipation and preventing solder bridges by increasing the pitch and width of external wiring terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a resin package is used for mounting optical elements, then the package structure is simple and easy to manufacture, but the thermal conductivity is low (0.5 W/m/deg) resulting in poor heat dissipation
Solution Approach 1:
The patent changes the material parameter of the package from resin to metal, specifically utilizing the high thermal conductivity of metal materials to improve heat dissipation efficiency while maintaining package functionality
Solution Approach 2:
The patent employs a composite structure combining metal frame body with resin sealing, where the metal frame provides thermal conduction pathways while the resin provides sealing and insulation, creating a hybrid package structure that leverages advantages of both materials
2Length of moving object
If the width of the package is reduced for miniaturization, then the optical pickup becomes more compact, but the pitch between external wiring terminals becomes too small causing solder bridges during mounting
Solution Approach 1:
The patent rearranges the external wiring terminals from a linear arrangement along the width direction to a distributed arrangement utilizing both length and width directions, effectively increasing the available spacing area and preventing solder bridges while maintaining compact package width
Solution Approach 2:
The patent segments the external wiring terminals into multiple groups arranged in different regions of the package, with sufficient spacing between groups to prevent solder bridges, while each group maintains necessary pin density for high performance
3Reliability
If the pitch between external wiring terminals is increased to prevent solder bridges, then mounting reliability improves, but the number of pins that can be accommodated in a given width decreases
Solution Approach 1:
The patent transitions from a one-dimensional linear arrangement of terminals to a two-dimensional distributed arrangement, allowing more terminals to be accommodated with adequate spacing by utilizing both length and width dimensions of the package
4Power
If the driving current of the laser is increased to achieve high power (200 mW or more), then the optical output increases for high-speed recording, but the temperature of the laser device increases reducing reliability
Solution Approach 1:
The patent introduces a metal frame body as a thermal intermediary between the laser device and the external environment, providing efficient heat conduction pathways that transfer heat away from the laser device to maintain lower operating temperatures during high power operation
Solution Approach 2:
The patent replaces the resin package with a metal frame body structure, utilizing the superior thermal conduction properties of metal to substitute for the inadequate heat dissipation mechanism of resin, thereby enabling effective thermal management at high power levels
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 thermal dissipation while maintaining slimness, allowing for a higher number of pins and preventing solder bridges, thus improving mountability and reliability.
Implementation Method 1
utilizing high thermal conductivity metal for efficient heat dissipation
Data Source
AI summary
A copper frame plate (2) has a central frame plate (2a) and a pair of side frame plates (2c) bent from both ends of the central frame plate. A flexible substrate (3) has a central substrate (3a) covering the central frame plate and bent substrates (3b) bent from the central substrate so as to cover the side frame plates. An optical element (4) is mounted on the central frame plate. A plurality of internal wiring terminals (9) connected to the optical element are disposed on the central substrate and arranged in the width direction (W) along which the pair of side frame plates are opposed to each other. A plurality of external wiring terminals (11) used for connection to external equipment are disposed on the bent substrates and arranged in the length direction (L) orthogonal to the width direction.