Capacitive Sensor for Compressive Load Measurement
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Solution Overview
Problem
Measuring and monitoring compressive loads between a processor and a heat spreader in electronic packages is challenging due to limited compliance in thermal interface materials and restricted space, which can lead to electrical failures if compression forces exceed certain levels.
Innovation Solution
An apparatus and method involving a sensor assembly with a cap and pin movable within a piston, utilizing a compliant film to measure deformation and determine compressive load, including a capacitive sensor to quantify the distance between the cap and pin, allowing for in situ monitoring of compressive loading during assembly and in-field applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional load cells are used to measure compressive load, then measurement capability is provided, but device complexity increases and space requirements exceed available space
Solution Approach 1:
The patent extracts the measurement function from a traditional load cell and implements it using a simplified capacitive sensor system. The capacitive sensor measures deformation of the compliant film directly, eliminating the need for complex load cell mechanisms while maintaining measurement capability.
Solution Approach 2:
The patent replaces the mechanical measurement system (traditional load cell) with an electrical measurement system (capacitive sensor). The capacitive sensor detects mechanical deformation through electrical field changes, substituting mechanical measurement components with electrical sensing components that require less space and complexity.
2Measurement precision
If traditional load cells are used to measure compressive load, then measurement capability is provided, but the space required exceeds available space in the electronic package
Solution Approach 1:
The patent nests the capacitive sensor assembly within the existing piston structure of the electronic package. The sensor is integrated into the compliant film mechanism already present, allowing measurement functionality to be embedded within existing components rather than adding separate external measurement devices.
Solution Approach 2:
The patent uses the compliant film itself as the sensing element. The thin flexible film deforms under compressive load, and this deformation is measured by the capacitive sensor. By using the existing thin film structure as part of the measurement system, the patent avoids adding bulky rigid sensor components.
3Measurement precision
If the compliant film deforms under compressive load, then load measurement is enabled, but electrical failures occur if compression forces exceed certain levels
Solution Approach 1:
The patent implements feedback by continuously monitoring the deformation of the compliant film through the capacitive sensor and using this information to determine when compressive forces approach dangerous levels. This feedback mechanism allows for real-time assessment of load conditions to prevent electrical failures.
Solution Approach 2:
The patent performs preliminary measurement and monitoring of compressive forces during assembly and operation, allowing detection of potentially dangerous load conditions before they cause electrical failures. By measuring load in advance, the system can take preventive action before damage occurs.
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
Enables accurate measurement and monitoring of compressive loads, preventing electrical failures by maintaining load within safe limits while ensuring proper soldered connections, thus ensuring the reliability of electronic packages.
Implementation Method 1
a capacitive sensor to quantify the distance between the cap and pin
Implementation Method 2
a compliant film disposed between the first and second elements as the compressive load is applied
Data Source
AI summary
An apparatus for determining a magnitude of a compressive load applied to a piston including a compliant film disposed between first and second elements is provided. The apparatus includes a first part movable with the first element in a movement direction along which the magnitude of the compressive load is to be determined, a second part movable with the second element in the movement direction and a sensor to measure a distance between the first and second parts in the movement direction, the measured distance being related to a deformation of the compliant film as the compressive load is applied.