SiP Optical Sensor Air Venting via Substrate Trenches
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Solution Overview
Problem
Conventional optical sensor packages face issues with foreign material contamination and humidity exposure due to air vents, which can affect the reliability of the sensors, and the gluing process often blocks these vents during assembly.
Innovation Solution
The introduction of air vent channels formed by through-holes and trenches in the substrate, which extend into optically isolated chambers, allowing for effective venting and protection of the sensor components while preventing foreign material entry and humidity exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If air vents are provided between the window and the cap to allow venting during assembly, then the assembly process is facilitated, but foreign material may enter the optical sensor package and humidity may expose internal components
Solution Approach 1:
The air vent is segmented into multiple components: a through-hole in the substrate, trenches extending from the through-hole, and a cover structure. This segmentation allows the vent to provide necessary airflow during assembly while the cover and trench structure prevent foreign material entry and humidity exposure to internal components.
Solution Approach 2:
The cover structure acts as an intermediary element that closes the air vent after assembly, preventing foreign material and humidity from entering while maintaining the venting function during the assembly process. The trenches also serve as intermediary structures that guide and control the airflow path.
2Reliability
If glass windows are attached to the cap during assembly, then the optical sealing is improved, but glue may overflow and block the air vent
Solution Approach 1:
The air vent structure (through-hole and trenches) is formed in the substrate before the glass windows are attached to the cap. This preliminary formation ensures that the vent pathway is established and protected, preventing glue overflow from blocking the vent during the subsequent window attachment process.
Solution Approach 2:
The cover structure serves as an intermediary that manages the air vent opening, allowing it to remain open during assembly for proper venting while being positioned and structured to prevent glue contamination. The cover can be selectively opened or closed during different assembly stages.
Data Source
AI summary
One or more embodiments are directed to system in package (SiP) for optical devices, including proximity sensor packaging. One embodiment is directed to an optical sensor that includes a substrate and a sensor die. A through-hole extends through the substrate, and a trench is formed in a first surface of the substrate and is in fluid communication with the through-hole. The sensor die is attached to the first surface of the substrate and covers the first through-hole and a first portion of the trench. A second portion of the trench is left uncovered by the sensor die.