Flip-Chip Pressure Sensor with Flexible PCB Opening
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Solution Overview
Problem
Pressure measurement devices face reliability and lifespan issues when operating in harsh environments with varying temperatures and chemically-reactive substances, as existing configurations are not adequately protected and fail to detect pressure increases within enclosures, such as batteries, leading to potential device destruction.
Innovation Solution
A pressure measurement apparatus comprising a semiconductor die with a micro-mechanical element and a flexible circuit board, attached in a flip chip configuration with an underfill material and coating for enhanced protection, allowing for early detection of pressure increases within a hermetically-sealed battery enclosure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor die is attached in a conventional configuration, then the connection to electrically conductive lines is simplified, but the active side of the semiconductor die is exposed to harsh environmental conditions, reducing device reliability and lifespan
Solution Approach 1:
The semiconductor die is attached in a flip-chip configuration, inverting the conventional mounting orientation. The active side faces upward toward the opening in the circuit board, allowing the back side to be protected while maintaining electrical connectivity through the inverted arrangement.
Solution Approach 2:
The electrical connection is established through the third dimension by using vertical conductive paths (via holes) in the circuit board that connect to the bottom surface of the flipped semiconductor die, allowing connections without exposing the active side to harsh environments.
2Reliability
If the semiconductor die is protected from environmental conditions, then reliability increases, but pressure measurement capability may be compromised
Solution Approach 1:
The circuit board is designed with a separate opening region that isolates the pressure access path from the semiconductor die mounting area. This segmentation allows the die to be protected while maintaining a dedicated pathway for pressure to reach the micro-mechanical element through the opening.
Solution Approach 2:
The opening in the circuit board acts as an intermediary structure that mediates between the external pressure environment and the protected semiconductor die. It allows pressure transmission while physically separating the sensitive die from harsh environmental conditions.
3Adaptability or versatility
If a rigid circuit board is used, then structural stability is maintained, but the apparatus cannot be adapted to difficult-to-access locations
Solution Approach 1:
The circuit board is designed as a flexible rather than rigid structure, allowing it to dynamically adapt to different geometries and difficult-to-access locations while maintaining sufficient structural integrity for the application. The flexibility enables conformal mounting in various positions without compromising strength.
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 increases the reliability and lifespan of pressure measurement devices by protecting them from harsh conditions and enabling early detection of pressure increases within battery enclosures, thus enhancing safety and preventing device destruction.
Implementation Method 1
The micro-mechanical element is configured to generate a measurement signal in response to an external pressure applied to the micro-mechanical element
Data Source
AI summary
An apparatus for measuring a pressure includes a semiconductor die and a circuit board. The semiconductor die includes a micro-mechanical element generating a measurement signal indicating information on an external pressure applied to the micro-mechanical element. The semiconductor die further includes an output interface providing the measurement signal. The circuit board includes at least one electrically-conductive line and an opening. The semiconductor die is attached to the circuit board, so that the micro-mechanical element faces the whole of the circuit board and the at least on electrically-conductive line is connected to the output interface.