Overmolded Leadframe Force Sensor with Multiple Mounting Positions
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Solution Overview
Problem
Existing force sensors are costly and inflexible, lacking a universal platform for various applications due to complex manufacturing processes and high component costs, particularly in medical and industrial settings.
Innovation Solution
A force sensor design featuring a sense die coupled to a leadframe with an encapsulant, utilizing mechanical and gel coupling mechanisms, and a slab die with uniform height, providing a low-cost and adaptable solution for diverse applications by integrating piezoresistive sensing elements and flexible actuation elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard surface micromechanical processes and vacuum cavity structures are used to create force/pressure transducers, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces expensive, complex vacuum cavity-based silicon pressure sensors with a simple, low-cost force sensor design that uses a leadframe, molding compound, and basic piezoresistive elements. This disposable-style approach maintains adequate measurement precision while dramatically reducing manufacturing complexity and cost.
Solution Approach 2:
The invention extracts and eliminates the complex vacuum cavity structure from traditional force sensors, retaining only the essential piezoresistive sensing elements on a leadframe. This simplification removes the need for expensive vacuum deposition and complex semiconductor manufacturing processes.
2Measurement precision
If force sensors are designed with specific mounting configurations, then measurement precision is improved, but adaptability to different applications decreases
Solution Approach 1:
The patent creates a universal force sensor platform where the sensing element can be positioned at multiple locations on the leadframe (front, rear, left, right sides). The molding compound structure provides consistent mechanical coupling and force transmission regardless of sensor position, enabling the same basic design to serve multiple mounting configurations and applications.
Solution Approach 2:
The invention allows dynamic positioning of the piezoresistive sensing element relative to the applied force source. The molding compound creates flexible mechanical coupling that maintains measurement accuracy whether the sensor is positioned to measure forces from the front, rear, or sides, adapting to different application requirements.
3Measurement precision
If multiple components are used to achieve force sensing functionality, then measurement precision is improved, but ease of manufacture worsens
Solution Approach 1:
The patent merges the force sensing function, mechanical coupling, and structural support into a single integrated molding compound structure. The leadframe with piezoresistive elements is encapsulated in molding compound that simultaneously provides mechanical support, force transmission, and protection, eliminating the need for separate components and complex assembly processes.
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 offers a cost-effective, flexible, and highly customizable force sensor platform capable of measuring forces across a wide range, suitable for various applications with improved durability and accuracy.
Implementation Method 1
utilizing mechanical and gel coupling mechanisms, and a slab die with uniform height, providing a low-cost and adaptable solution for diverse applications by integrating piezoresistive sensing elements
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3A~3C
AI summary
A force sensor (100, 200, 300, 400, 500) comprising: a leadframe (102) comprising: a base having a first major surface and an opposing second major surface, with a base side wall extending between the first major surface and the opposing second major surface; a plurality of conductive traces supported by the base; a plurality of leads (116) each electrically coupled to one or more of the plurality of conductive traces, each of the plurality of leads having a lead end that is spaced from the base; a sense die (104, 204) electrically coupled to two or more of the plurality of conductive traces, the sense die comprising one or more piezoresistive sensing elements for sensing a force applied to the sense die, wherein the sense die comprises a first major surface and an opposing second major surface, with a sense die side wall extending between the first major surface and the opposing second major surface, and wherein the opposing second major surface of the sense die faces the first major surface of the base; and an encapsulant (108) engaging both the base and the sense die for providing structural rigidity to the force sensor, wherein the lead end of at least some of the plurality of leads extends outside of the encapsulant to allow for an electrical coupling of the lead end to an external component.