Elastic-Wave Filter Substrate Step Reduction
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Solution Overview
Problem
The conventional elastic-wave filter device manufacturing process is complicated due to the need for differently sized pillar-like wiring electrodes to accommodate the thickness difference between first and second piezoelectric substrates, leading to a greater step between the top faces and undersides of the substrates, which complicates the formation of flush externally connecting terminals.
Innovation Solution
The elastic-wave filter device design reduces the step between the top faces of the first and second piezoelectric substrates by making the first substrate thicker, allowing for a smaller difference in pillar-like wiring electrode heights and simplifying the manufacturing process, with the sealing member integrating the substrates to form a downsized device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the first piezoelectric substrate is made thicker than the second piezoelectric substrate, then the distance between top faces is reduced, but the distance between undersides increases, complicating the formation of flush externally connecting terminals
Solution Approach 1:
The patent introduces a horizontal dimension solution by having the first pillar-like wiring electrode extend laterally beyond the first piezoelectric substrate. This allows the electrode to reach the second piezoelectric substrate level horizontally, eliminating the need for vertical height adjustment and simplifying the formation of flush externally connecting terminals.
Solution Approach 2:
The first pillar-like wiring electrode is segmented into multiple portions: a first portion extending from the first IDT electrode, a second portion extending laterally beyond the first substrate, and a third portion connecting to the second substrate. This segmentation allows each portion to be optimized independently for its specific function.
2Ease of operation
If the pillar-like wiring electrodes are made of different heights to accommodate substrate thickness difference, then the externally connecting terminals can be formed on different substrate levels, but the manufacturing process becomes more complicated
Solution Approach 1:
Instead of adjusting electrode heights in the vertical dimension, the patent extends the first pillar-like wiring electrode in the horizontal dimension beyond the first substrate. This lateral extension allows the electrode to reach the second substrate level without requiring different heights, simplifying the manufacturing process.
Solution Approach 2:
The first pillar-like wiring electrode serves multiple functions: it provides electrical connection from the first IDT electrode, extends laterally to reach the second substrate level, and forms the externally connecting terminal. This multi-functionality eliminates the need for separate height-adjustment mechanisms.
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 design simplifies the manufacturing process by reducing the height difference between the pillar-like wiring electrodes and allows for easier handling and integration of the filter device, improving filter characteristics and reducing manufacturing complexity.
Implementation Method 1
first piezoelectric substrate 103, second piezoelectric substrate 105... first IDT (interdigital transducer) electrode 102 on its top face... second IDT electrode 104 on its top face
Implementation Method 2
sealing member 106 includes first sealer 106A and second sealer 106B... first sealer 106A is formed such that it covers at least an underside of first piezoelectric substrate 103 and an underside of second piezoelectric substrate 105
Data Source
AI summary
An elastic-wave filter device includes a first piezoelectric substrate, a second piezoelectric substrate, a first pillar-like wiring electrode, and a second pillar-like wiring electrode. The first and second substrates have a first and a second IDT electrodes on their top faces respectively. A lateral face of the second substrate confronts a lateral face of the first substrate. The first pillar-like electrode and the second pillar-like electrode are formed above the first and the second substrates respectively, and are electrically connected to the first and the second IDT electrodes respectively. The first substrate is thicker than the second substrate. A distance between a plane including the top face of the first substrate and a plane including the top face of the second substrate is smaller than a distance between a plane including an underside of the first substrate and a plane including an underside of the second substrate.