Leadless Pressure Sensor Hermetic Package for High-Temperature Sensing
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Solution Overview
Problem
Existing semiconductor pressure sensors fail at high temperatures due to inter-metallic diffusion in wire bonds, mechanical fatigue from vibration, and chemical reactions at the contact points of conductive frits, making them unsuitable for harsh environments.
Innovation Solution
A leadless pressure sensor design using co-fired non-conductive glass frit films and conductive metal films in a single layer, providing mechanical coupling and electrical connectivity, with glass frit ensuring bonding strength and hermeticity, and metal paste ensuring electronic connectivity, while being tolerant to surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonds are used for electrical connection, then electrical connectivity is achieved, but inter-metallic diffusion occurs at high temperatures causing failure
Solution Approach 1:
The patent removes wire bonds from the system entirely, replacing them with a leadless design where the substrate itself provides both mechanical support and electrical connection pathways through conductive traces integrated into the substrate structure. This extraction eliminates the inter-metallic diffusion problem that plagues wire bond connections at high temperatures.
Solution Approach 2:
The patent introduces an intermediate layer structure between the sensing element and external connections, using a combination of conductive and non-conductive films that serve as mediators. This intermediate structure provides both electrical connectivity and mechanical bonding without the high-temperature failure modes of traditional wire bonds.
2Reliability
If conductive frit is used for electrical connection, then electrical connectivity is achieved, but chemical reactions occur at contact points causing failure
Solution Approach 1:
The patent removes conductive frit from the system, replacing it with metal trace patterns deposited on the substrate. This extraction eliminates the chemical reaction problems that occur at frit contact points, as the metal traces provide stable electrical connections without the chemical instability of conductive frit materials.
Solution Approach 2:
The patent employs composite material structures combining metal traces with substrate materials to achieve both electrical conductivity and chemical stability. The composite structure provides robust electrical connections that resist chemical degradation at high temperatures.
3Strength
If traditional bonding methods are used, then mechanical coupling is achieved, but surface roughness causes bonding failures
Solution Approach 1:
The patent employs thin film structures that can conform to surface irregularities, providing robust mechanical coupling even when surfaces are not perfectly smooth. The film structure accommodates surface roughness while maintaining bonding integrity.
Solution Approach 2:
The patent uses composite material systems that combine multiple layers with different properties, where the combination provides both mechanical strength and tolerance for surface variations. The composite structure distributes stresses and accommodates roughness that would cause failures in single-material bonding.
4Ease of operation
If sensing elements are exposed to environment, then pressure detection is enabled, but contamination and harsh conditions cause failure
Solution Approach 1:
The patent divides the device into separate functional zones: an environmental exposure zone for pressure detection and a protected zone for sensitive electronics. This segmentation allows the sensing function to interact with the environment while keeping vulnerable components isolated from contamination and harsh conditions.
Solution Approach 2:
The patent employs thin film membranes that act as barriers, allowing pressure transmission while blocking contamination. These films enable the sensing elements to detect environmental pressure changes without direct exposure to harmful contaminants.
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 design withstands high temperatures (400° C. to 700° C.) by isolating sensing elements from the environment, preventing contamination and failure, and maintaining robust bonding and electrical connection.
Implementation Method 1
one or more non-conductive glass frit films configured to mechanically couple the substrate to the connecting assembly to form an internal hermetic chamber, where the one or more non-conductive glass frit films are located on the second surface of the substrate
Implementation Method 2
one or more conductive metal films configured to electrically couple the substrate to the connecting assembly, where the one or more conductive films are located on the second surface of the substrate, and where the one or more non-conductive glass frit films and the one or more conductive metal films are co-fired in a similar layer
Implementation Method 3
one or more non-conductive glass frit films and the one or more conductive metal films are co-fired in a similar layer
Data Source
AI summary
A leadless pressure sensor may include a substrate including a first surface in communication with an environment and a second surface opposite the first surface. The pressure sensor may include a sensing element located on the second surface for measuring a parameter associated with the environment. The pressure sensor may include a connecting assembly. The pressure sensor may include a sensing package. The sensing package may include one or more non-conductive glass frit films configured to mechanically couple the substrate to the connecting assembly to form an internal hermetic chamber. The sensing package may include one or more conductive metal films configured to electrically couple the substrate to the connecting assembly, where the one or more non-conductive glass frit films and the one or more conductive metal films are co-fired in a similar layer.