Ultrasonic Probe FPC Stiffness Reinforcement for Warping Prevention
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Solution Overview
Problem
Conventional ultrasonic probes face challenges in downsizing due to wire bonding, which causes discomfort during medical diagnostics and can lead to mechanical and electrical reliability issues due to warping of the flexible printed circuit (FPC) during bump press-fitting, resulting in uneven contact and potential contact failures.
Innovation Solution
The ultrasonic probe incorporates a stiffness reinforcement on the FPC in areas without bumps, ensuring even pressure distribution and preventing warping, thereby enhancing mechanical and electrical reliability by using reinforcing pads with the same thickness as the pads on the FPC, which are formed during the pad formation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding is used to connect electrode pads to the printed-circuit board, then electrical connection is established, but the probe size increases and protrusions cause discomfort to the examinee
Solution Approach 1:
The patent removes the wire bonding process entirely and replaces it with a direct bump press-fitting method. The wire bonding step is extracted from the connection process, eliminating the need for wires and their associated space requirements, thereby reducing probe size while maintaining electrical connection reliability
Solution Approach 2:
The patent replaces the mechanical wire bonding system with a bump press-fitting system. Instead of using wires to establish electrical connections, the invention uses direct metal-to-metal contact through bumps pressed into via holes, eliminating protrusions and reducing probe size while maintaining reliable electrical connectivity
2Volume of moving object
If bump press-fitting is used to connect electrode pads to the FPC, then wire bonding is eliminated and probe size is reduced, but the FPC warps due to pressure concentration, causing uneven contact and potential contact failures
Solution Approach 1:
The patent applies different structural characteristics to different regions of the FPC. Reinforcement patterns are added specifically to areas where bumps are pressed, providing localized stiffness enhancement. This allows the FPC to maintain flexibility where needed while gaining rigidity at critical connection points, preventing warping and ensuring reliable contact without increasing overall probe size
Solution Approach 2:
The patent preemptively adds reinforcement patterns to the FPC before the bump press-fitting process. These reinforcement structures act as a cushion against warping by distributing the pressing pressure evenly across the FPC surface. By preparing the FPC in advance with these reinforcement features, the patent prevents contact reliability issues before they occur during the bonding process
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 solution prevents warping of the FPC during press-fitting, ensures all bumps are properly fitted, and provides a reliable mechanical and electrical connection, enhancing the ultrasonic probe's performance and comfort during use by eliminating unnecessary protrusions and ensuring consistent contact.
Implementation Method 1
a PMUT (Piesoelectric Micro-machined Ultrasonic Transducer) using a piezo element
Implementation Method 2
a CMUT (Capacitive Micro-machined Ultrasonic Transducer) using a capacitive transducer
Data Source
AI summary
Provided is an ultrasonic probe having ultrasonic elements and a printed-circuit board that establishes connection between the ultrasonic elements and external wiring, achieving strong connection between the ultrasonic elements and the printed-circuit board mechanically and electrically, and thereby improving performance in examination and diagnosis using the ultrasonic probe. The printed-circuit board with pads each having a via-hole to be bonded to electrode pads of a chip equipped with the ultrasonic elements, is provided with a reinforcement, in an area of the base material where the pad having the via-hole is not formed. The reinforcement is formed simultaneously with forming the pads and wiring on the printed-circuit board, having the same thickness as the pads. With the reinforcement, pressure is evenly applied to the printed-circuit board when the electrode pad is press-fitted into the pad having the via-hole, thereby preventing warping and deforming of the board.