Optical Sensor Surface-Mount Design for Density and Heat Isolation
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Solution Overview
Problem
Existing optical sensors, such as infrared sensors, face challenges in increasing mounting density and reducing size due to the presence of through-holes in through-hole mount devices, which limit design freedom and make it difficult to concurrently mount both through-hole and surface mount devices on a single substrate, and they often suffer from sensitivity decreases and malfunctions due to heat conduction.
Innovation Solution
The optical sensor design features a light receiver located on a circuit portion with a substrate, an electronic component covered by resin, and a metal pillar electrically connected to the component, allowing for increased design freedom and reduced size, with the metal pillar exposed to function as an external terminal and providing mechanical and electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If through-hole mount devices are used for optical sensors, then mechanical strength and electrical connection are improved, but mounting density and substrate size are reduced
Solution Approach 1:
The patent transitions from through-hole mounting (requiring vertical penetration through the substrate) to surface-mount technology where the optical sensor is mounted on the surface of the substrate. This dimensional change eliminates the need for through-holes, allowing higher mounting density and smaller substrate size while maintaining mechanical strength through surface mounting techniques.
2Reliability
If through-hole mount devices are used for optical sensors, then electrical connection is improved, but design freedom is reduced
Solution Approach 1:
The patent employs surface-mount technology instead of through-hole mounting, allowing the optical sensor to be positioned and connected on the substrate surface. This provides greater design freedom in layout arrangement, signal routing, and component placement while maintaining reliable electrical connections through surface-mounted conductive paths and contact pads.
3Measurement precision
If light receiver is exposed without protection, then sensitivity is improved, but heat conduction causes malfunction
Solution Approach 1:
The patent uses a transparent resin cover (thin film) that protects the light receiver from direct thermal contact with the substrate and surrounding environment while allowing optical signals to pass through. This resin enclosure isolates the light receiver from harmful heat conduction paths, preventing thermal-induced malfunctions while maintaining optical sensitivity.
Solution Approach 2:
The patent introduces a transparent resin as an intermediary material between the light receiver and the external environment. This resin acts as a thermal barrier that blocks harmful heat conduction to the light receiver while being transparent to the optical signals, thus protecting the sensor from thermal interference without affecting its sensitivity.
Data Source
AI summary
An optical sensor includes a light receiver and a circuit portion electrically connected to the light receiver, and the circuit portion includes a substrate, an electronic component on the substrate, a resin covering the electronic component, and a metal pillar electrically connected to the electronic component and including a portion covered with the resin and a portion exposed from the resin, and the light receiver is located on the circuit.