Acoustic Wave Element Mounting on High-Frequency Device Substrate
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Solution Overview
Problem
Acoustic wave elements embedded in circuit substrates deteriorate due to heat and pressure during substrate formation, and those mounted on the surface are prone to damage from impact.
Innovation Solution
A high-frequency device design with an acoustic wave element located on the lower surface of the circuit substrate, protected by bumps and a specific path structure that reduces contact risk during mounting, using a stacked dielectric layer configuration with capacitors and an inductor to form a resonant circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the acoustic wave element is embedded in the circuit substrate, then the device integration is improved, but the acoustic wave element deteriorates due to heat and pressure during substrate formation
Solution Approach 1:
Instead of embedding the acoustic wave element in the upper surface of the circuit substrate, the invention inverts the arrangement by placing the acoustic wave element on the lower surface of the substrate. This inversion allows the element to be protected from heat and pressure during substrate formation processes while maintaining good electrical connection through the substrate thickness.
Solution Approach 2:
The acoustic wave element is mounted on the lower surface before the upper surface of the circuit substrate is formed. This preliminary action ensures the element is in place and protected before subsequent high-temperature and high-pressure formation processes occur on the upper surface, preventing deterioration.
2Device complexity
If the acoustic wave element is mounted on the surface of the circuit substrate, then the electrical connection is simplified, but the element is prone to damage from impact
Solution Approach 1:
The invention inverts the conventional mounting approach by placing the acoustic wave element on the lower surface rather than the upper surface of the circuit substrate. This inversion protects the element from impact damage while maintaining electrical connection through the substrate via conductive paths or via holes.
Solution Approach 2:
The circuit substrate itself acts as a protective cushioning layer between the acoustic wave element on the lower surface and external impact forces. This beforehand cushioning structure absorbs impact energy before it can reach the sensitive acoustic wave element, preventing damage.
3Reliability
If the acoustic wave element is placed on the lower surface with protective structures, then the element protection is improved, but the device structure becomes more complex
Solution Approach 1:
The circuit substrate serves multiple functions simultaneously: it provides electrical connection between the acoustic wave element and external terminals, offers mechanical protection against impact, and enables heat dissipation. This multi-functionality reduces the need for separate protective structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The invention merges the protective function with the existing circuit substrate structure rather than adding separate protective components. The substrate's physical presence and structural integrity are utilized to provide protection, combining multiple functions into a single integrated component and minimizing additional complexity.
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 effectively protects the acoustic wave element from damage, maintains its functionality, and achieves a steep transition between passband and stopband in frequency filtering, enhancing the device's performance and reliability.
Implementation Method 1
an acoustic wave element located on the first surface and electrically connected to the passive element through a second path in the circuit substrate
Implementation Method 2
a circuit substrate including dielectric layers that are stacked
Data Source
AI summary
A high-frequency device includes: a circuit substrate including dielectric layers that are stacked, wiring patterns located on at least one of the dielectric layers, and a passive element formed of at least one of the wiring patterns, the circuit substrate having a first surface that is a surface of an outermost dielectric layer in a stacking direction of the dielectric layers; a terminal for connecting the high-frequency device to an external circuit, the terminal being located on the first surface and electrically connected to the passive element through a first path in the circuit substrate; and an acoustic wave element located on the first surface and electrically connected to the passive element through a second path in the circuit substrate.