Optical Sensor Package with Partition Walls for Crosstalk Control
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Solution Overview
Problem
Semiconductor packages face challenges in preventing light crosstalk between light-emitting and light-receiving units, which deteriorates sensing sensitivity, and warpage during manufacturing processes affects process yield.
Innovation Solution
The optical sensor package incorporates a partition wall between the light-emitting and light-receiving units, using black epoxy molding compound for transfer molding, and a clear molding compound for encapsulation, with the semiconductor chip acting as a partition to prevent direct light entry and enhance sensing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a partition wall is formed between light-emitting and light-receiving units, then light crosstalk is prevented and sensing sensitivity is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The package substrate is divided into multiple substrate units, each containing a light-emitting unit and a light-receiving unit. Partition walls are formed between adjacent substrate units to prevent light crosstalk. This segmentation allows independent optical paths while maintaining a compact integrated structure, resolving the contradiction between preventing light crosstalk and maintaining structural simplicity.
Solution Approach 2:
A molding member is introduced as an intermediary component that encapsulates the substrate units and provides additional light shielding. The molding member fills the spaces between substrate units and works in conjunction with partition walls to block stray light, thereby enhancing light isolation without requiring complex internal partition structures in each substrate unit.
2Productivity
If multiple substrate units are mounted on a substrate strip, then manufacturing efficiency is improved, but warpage occurs during the manufacturing process
Solution Approach 1:
The physical and chemical parameters of the molding compound are optimized to match the substrate material properties. The molding compound is formulated with specific viscosity, curing characteristics, and thermal expansion coefficients that compensate for warpage tendencies during the molding process, allowing efficient batch manufacturing without substrate deformation.
Solution Approach 2:
A composite structure is created by encapsulating multiple substrate units with a molding member that forms a unified package. This composite packaging approach distributes mechanical stresses evenly across all substrate units, preventing warpage while enabling efficient batch production. The molding member acts as a unifying structure that maintains dimensional stability during and after manufacturing.
3Volume of moving object
If the light-receiving unit is disposed opposite to the light-emitting unit with respect to the semiconductor chip, then compact packaging is achieved, but direct light entry causes crosstalk
Solution Approach 1:
The package is segmented into multiple substrate units mounted on a substrate strip. Each substrate unit contains a light-emitting unit and a light-receiving unit positioned in laterally adjacent rather than directly opposite locations. Partition walls are formed between adjacent substrate units to block light paths, enabling compact packaging without direct light exposure between emitting and receiving units.
Solution Approach 2:
The optical path is reconfigured from a vertical arrangement (directly opposite positions) to a lateral arrangement (adjacent positions on the substrate plane). This dimensional change in component layout, combined with partition walls and molding member shielding, prevents direct light entry while maintaining compact package dimensions through efficient use of planar space.
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
The solution effectively prevents light crosstalk, improving sensing sensitivity and reducing warpage-related manufacturing issues, thereby enhancing the overall performance and yield of the optical sensor package.
Implementation Method 1
forming a partition wall using a black epoxy molding compound
Implementation Method 2
forming a molding member, using an encapsulant, in each of the substrate units
Data Source
AI summary
According to an embodiment, a method of manufacturing an optical sensor package includes forming a partition wall in each of substrate units on a substrate strip, mounting sensor elements on each of the substrate units, the sensor elements including a light-emitting unit and a light-receiving unit, and forming a molding member, using an encapsulant, in each of the substrate units, wherein the partition wall is arranged between the light-emitting unit and the light-receiving unit.