Sensor Package Light Filter Cavity for Lower-Cost Wavelength Filtering
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Solution Overview
Problem
Existing methods for filtering specific wavelengths of light in semiconductor packages are expensive due to the need to cover all package components with transparent mold compounds or inefficient application processes of light filter films.
Innovation Solution
A sensor package design that includes an opaque mold compound covering most components and a cavity for a wavelength-specific light filter made of silicone, epoxy, and organic dye, applied directly to the light sensor area, reducing costs and enabling precise wavelength filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transparent mold compound is used to cover all package components for wavelength-specific light filtering, then light filtering effectiveness is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent divides the package into two distinct regions: an opaque mold compound covering most components and a transparent or translucent light filter material covering only the light sensor area. This segmentation allows wavelength-specific filtering to be applied selectively only where needed, rather than covering the entire package, thereby reducing material costs and manufacturing complexity while maintaining filtering effectiveness.
Solution Approach 2:
The patent applies different material properties to different locations within the package. The light sensor area receives a transparent or translucent light filter material with specific wavelength filtering properties, while the rest of the package uses opaque mold compound. This local differentiation optimizes both filtering performance and manufacturing efficiency by applying expensive specialized materials only where functionally necessary.
2Reliability
If light filter film is applied to the entire semiconductor die at the wafer stage, then wavelength filtering is achieved, but material waste and application complexity increase
Solution Approach 1:
The patent segments the light filter application to cover only the light sensor area rather than the entire semiconductor die. This is achieved by forming a cavity in the mold compound that exposes only the light sensor region, allowing the light filter material to be applied precisely where needed and eliminating waste from covering non-functional areas.
Solution Approach 2:
The patent performs preliminary action by forming the cavity in the mold compound before applying the light filter material. This pre-prepared cavity structure guides the light filter material to the exact location needed, preventing material waste and simplifying the application process by eliminating the need for subsequent removal or trimming operations.
3Reliability
If light filter film is applied at the wafer stage, then filtering is achieved, but the process is complex and inefficient
Solution Approach 1:
The patent performs preliminary action by forming the cavity in the mold compound during the molding process, before the light filter material is applied. This pre-formed cavity serves as a built-in application guide, simplifying the subsequent light filter deposition process and eliminating complex alignment and removal steps that would be required if filtering were applied at the wafer stage.
Solution Approach 2:
The patent merges the mold compound formation and light filter application into a more integrated process. By forming the cavity during molding and then applying the light filter material directly into this cavity, the patent combines what would otherwise be separate, complex steps into a more streamlined sequence, reducing overall process complexity.
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 provides effective and cost-efficient wavelength-specific light filtering, allowing for precise control over the wavelengths reaching the light sensor while minimizing material waste and application costs.
Implementation Method 1
The combination is configured to reject light having a wavelength in a target wavelength range
Implementation Method 2
curing the solution to form a light filter in the cavity
Data Source
AI summary
In examples, a method comprises covering at least part of a semiconductor die having a light sensor with a mold compound, the mold compound including a cavity over the light sensor. The method further comprises depositing a solution into the cavity to form a light filter, and curing the solution to form a light filter in the cavity.