Multi-layer Flex Circuit for Ultrasound Transducer Pitch Matching
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Solution Overview
Problem
The challenge in manufacturing ultrasound transducers is the close spacing of transducer elements, which is smaller than the minimum distance that can be achieved between conductors on a printed flex circuit, requiring innovative methods to connect signals effectively without compromising the integrity of the transducer array.
Innovation Solution
The use of multi-layer printed flex circuits with traces spaced farther apart than the transducer element pitch, connected using particulate-filled epoxy and laser processing to form electrical connections, allows for efficient signal routing and connection to transducer elements, even when the pitch is finer than conventional manufacturing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-layer printed flex circuit is used to connect transducer elements, then the manufacturing process is simple, but the traces cannot be spaced close enough to match the transducer element pitch
Solution Approach 1:
The patent transitions from a single-layer printed flex circuit to a multi-layer printed flex circuit structure. By adding the Z-dimension (multiple layers), the circuit can achieve equivalent trace spacing while maintaining simpler lateral routing. Each layer can be spaced farther apart laterally, while vertical stacking provides the necessary connection density to match transducer element pitch.
Solution Approach 2:
The multi-layer circuit structure embeds multiple trace layers within a compact vertical stack. Each layer contains traces that connect to specific transducer elements, with layers nested one above another. This nesting allows dense connectivity without requiring proportionally dense lateral spacing, as connections are distributed across multiple vertical levels.
2Manufacturing precision
If traces are spaced closer together to match transducer element pitch, then connection density improves, but manufacturing precision requirements increase beyond conventional capabilities
Solution Approach 1:
By moving the spacing challenge from the lateral (X-Y) plane to the vertical (Z) dimension through multi-layer construction, each individual layer can use larger, more manufacturable trace spacing. The cumulative effect of multiple layers provides the necessary connection density without requiring any single layer to achieve sub-conventional spacing precision.
3Area of stationary object
If the flex circuit size is minimized to match the compact transducer array, then device compactness improves, but trace routing becomes more difficult
Solution Approach 1:
The multi-layer structure nests multiple routing paths within a compact vertical stack, allowing traces to be routed through different vertical levels rather than competing for lateral space. This enables compact overall footprint while maintaining adequate routing width and spacing on each individual layer, as the routing density is distributed across multiple vertical levels.
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 approach enables reliable electrical connections between transducer elements and flex circuits, reducing signal cross-talk and improving manufacturing ease, while minimizing the size of the flex circuit, thus enhancing the performance and usability of ultrasound transducers.
Implementation Method 1
A laser is then used to remove the resist and expose the metallic conductor in areas where it is not wanted
Implementation Method 2
An etch processes then removes most of the exposed metallic conductor
Implementation Method 3
The resist that is located over the areas where the metallic conductor is desired is then removed with a solvent
Implementation Method 4
the traces in the multi-layer printed flex circuits are connected to transducer elements by securing the multi-layer printed flex circuit to the ultrasound transducer with a particulate filled epoxy material
Data Source
AI summary
The disclosed technology features methods for the manufacture of electrical components such as ultrasound transducers. In particular, the disclosed technology provides methods of creating an ultrasonic transducer by connecting one or more multi-layer printed circuits to an array of ultrasound transducer elements. In one embodiment, the printed circuits have traces in a single layer that are spaced by a distance that is greater than a pitch of the transducer elements to which the multi-layer printed circuit is to be connected. However the traces from all the layers in the multi-layer printed circuit are interleaved to have a pitch that is equal to the pitch of the transducer elements. The disclosed technology also features ultrasound transducers produced by the methods described herein.