Infrared Sensor Size Reduction via Dual-Package Lead Frame Design
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Solution Overview
Problem
Existing infrared sensors face challenges in minimizing size due to the requirement for deep penetrating openings in lead frames to accommodate both optical filters and sensor elements, leading to increased thickness and width, which restricts size reduction.
Innovation Solution
The infrared sensor design exposes lead terminals from mold members on specific side surfaces, allowing for shallower and narrower opening formations, reducing the overall size by eliminating the need for deep openings, and using mold members to connect these terminals for efficient packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the lead frame thickness is increased to accommodate deep opening portions for mounting optical filters and sensor elements, then the sensor element and optical filter can be properly mounted, but the overall size of the infrared sensor increases
Solution Approach 1:
The patent transitions from a traditional single-package design to a dual-package configuration where the optical filter and sensor element are mounted in separate packages. This dimensional reorganization eliminates the need for deep penetrating openings in a single thick lead frame, as each package can be independently optimized with shallower mounting structures. The optical filter package and sensor element package are then connected through wire bonding, achieving the mounting function without increasing overall sensor thickness.
2Volume of moving object
If deep penetrating openings are formed in the lead frame to accommodate both optical filter and sensor element, then proper mounting is achieved, but the width of the opening portion increases
Solution Approach 1:
The patent divides the traditional single lead frame structure into two separate lead frames, each associated with a distinct package. The optical filter is mounted in one package with its own lead frame, while the sensor element is mounted in another package with a separate lead frame. This segmentation eliminates the need for a single complex deep opening that must accommodate both components, replacing it with two simpler, shallower openings in separate structures. The packages are then electrically connected through wire bonding between the separate lead frames.
3Volume of moving object
If the opening portion depth is increased to allow mounting of optical filter and sensor element, then component accommodation is achieved, but both depth and width of opening portion increase
Solution Approach 1:
The patent resolves the depth constraint by reorganizing the mounting architecture from a vertical stacking approach (requiring deep openings) to a lateral separation approach. The optical filter and sensor element are mounted in separate packages at different lateral positions rather than stacked vertically in the same lead frame. This allows each package to have shallow opening portions while maintaining proper component accommodation through the wire bonding connection between packages.
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
This approach enables a decrease in the size of the infrared sensor compared to traditional designs by reducing the depth and width of opening portions, facilitating smaller sensor packages while maintaining effective electrical connections.
Implementation Method 1
an optical filter for selecting penetrating infrared light
Implementation Method 2
a sensor element for detecting the infrared light having penetrated the optical filter; the sensor element is a quantum-type photodiode generating a photovoltaic effect using an infrared ray
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3A~3C
AI summary
A filter member includes a first lead terminal, an optical filter, and a first mold member, and a light incidence surface and a light emission surface of the optical filter is exposed from the first mold member. A sensor member includes an IR sensor element, a second lead terminal and a second mold member. A light-receiving surface of the IR sensor element is exposed from the second mole member. The filter member is disposed on the sensor member so that the light emission surface of the optical filter faces the light-receiving surface of the IR sensor element in the sensor member.