Optically Transparent Mold Compound for IR and THz Sensor Packaging
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Solution Overview
Problem
Conventional optical sensor packages for IR and THz sensing lack sufficient optical transparency, leading to expensive packaging solutions and inadequate protection for the light sensor element, resulting in performance issues due to environmental stresses like moisture absorption and pollution.
Innovation Solution
Incorporating IR and THz transparent filler particles into a mold compound to create a fully encapsulating polymer-based material that provides at least 50% optical transparency for a minimum thickness of 500 μm, allowing for reliable operation and protection of the light sensor element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional epoxy-based mold compounds are used, then the package structure is simple and manufacturing is easy, but the optical transparency is insufficient for IR and THz sensing applications
Solution Approach 1:
The patent uses composite materials by combining polymer base mold compound with specific filler particles (such as aluminum oxide, aluminum nitride, or boron nitride) to create a mold compound that maintains ease of manufacture while achieving sufficient IR and THz optical transparency. The composite structure allows the material to process like conventional compounds while transmitting infrared and terahertz radiation.
Solution Approach 2:
The patent changes the physical and chemical parameters of the mold compound by controlling filler particle size (substantially uniformly distributed), filler concentration (30-90 volume percent), and particle morphology to optimize both manufacturability and optical transparency in the IR and THz ranges. These parameter adjustments enable the mold compound to maintain conventional processing characteristics while achieving the required optical properties.
2Illumination intensity
If open cavity or glass lid metallic package is used, then the optical transparency is improved, but the protection against environmental stresses is insufficient
Solution Approach 1:
The patent employs composite mold compounds with filler particles that provide both optical transparency for IR/THz sensing and environmental protection. The composite structure creates a hermetic seal around the sensor element, protecting it from moisture and pollution while maintaining the necessary optical transmission properties that open cavity designs cannot provide.
Solution Approach 2:
The mold compound acts as a protective encapsulating shell that fully encloses the sensor element, providing mechanical protection and environmental sealing. This encapsulation approach combines the protective benefits of closed packages with the optical transparency needed for sensing, eliminating the need for open cavity or glass lid designs.
3Ease of manufacture
If conventional mold compounds are used, then the manufacturing cost is low, but the sensitivity of the optical sensor is reduced due to insufficient transparency
Solution Approach 1:
The patent uses cost-effective composite mold compounds containing common filler materials like aluminum oxide, aluminum nitride, or boron nitride that can be processed using conventional semiconductor assembly equipment. These composites achieve sufficient IR and THz transparency to maintain sensor sensitivity while keeping manufacturing costs low compared to specialized transparent materials.
Solution Approach 2:
The patent optimizes filler particle parameters including size distribution (substantially uniform), concentration (30-90 volume percent), and morphology to maximize optical transparency in the IR and THz ranges while maintaining conventional manufacturability. These parameter optimizations ensure sensor sensitivity is not compromised while keeping production costs reasonable.
4Illumination intensity
If the light sensor element is exposed to air, then the optical transparency is maximized, but the sensor element is vulnerable to moisture absorption, pollution, and impact damage
Solution Approach 1:
The mold compound forms a protective encapsulating shell around the light sensor element that provides mechanical protection against impact damage and seals the element against moisture and pollution. This encapsulation maintains optical transparency for IR and THz wavelengths, allowing the sensor to operate with maximum sensitivity while being fully protected from environmental harmful factors.
Solution Approach 2:
The patent uses composite mold compounds that simultaneously provide optical transparency for sensing and environmental protection. The composite structure creates a hermetic barrier against moisture and contaminants while maintaining the optical transmission properties necessary for high-sensitivity IR and THz detection, eliminating the need to expose the sensor element to air.
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 enables cost-effective, optically transparent mold compounds that fully encapsulate the light sensor element, enhancing sensitivity and durability by allowing reliable IR and THz sensing while protecting against environmental stresses.
Implementation Method 1
the mold compound is optically transparent. As used herein the term 'optically transparent' for a mold compound means an optical transparency of at least 50% for a minimum mold thickness of 500 μm (0.5 mm) over a portion of at least one of an IR frequency range and a THz frequency range
Implementation Method 2
Disclosed filler particles render the mold compound IR and/or THz transparent in at least a portion of the IR and/or THz ranges
Data Source
AI summary
An optical sensor package includes an IC die including a light sensor element, an output node, and bond pads including a bond pad coupled to the output node. A leadframe includes a plurality of leads or lead terminals, wherein at least some of the plurality of leads or lead terminals are coupled to the bond pads including to the bond pad coupled to the output node. A mold compound provides encapsulation for the optical sensor package including for the light sensor element. The mold compound includes a polymer-base material having filler particles including at least one of infrared or terahertz transparent particle composition provided in a sufficient concentration so that the mold compound is optically transparent for providing an optical transparency of at least 50% for a minimum mold thickness of 500 μm in a portion of at least one of an infrared frequency range and a terahertz frequency range.