SAW Filter Busbar Layout for Hot Spot Reduction
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Solution Overview
Problem
High Power User Equipment (HPUE) and 5G RF components face challenges in managing high power levels, leading to power saturation and localized temperature gradients that can cause device failure, requiring effective thermal management to prevent early power compression and device damage.
Innovation Solution
A SAW filter device with a ladder type structure and enhanced thermal management using mechano-acoustic structures and connection circuitry, including broadened metallized areas and cascaded resonators, to create thermal radiators and improve heat dissipation without increasing chip size, ensuring better heat sinking and power resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power levels are handled by SAW filter device, then power handling capability is improved, but localized temperature gradients increase causing device failure
Solution Approach 1:
The patent converts the harmful thermal energy into beneficial thermal radiation by designing metallized areas that act as thermal radiators. The metallized areas, which are naturally present for electrical connectivity, are strategically designed to also serve as heat dissipation structures, transforming the thermal problem into a heat management solution through radiative cooling.
Solution Approach 2:
The patent addresses thermal management by transitioning from one-dimensional heat conduction through the substrate to two-dimensional thermal radiation from the metallized surfaces. By utilizing the surface area of metallized regions for thermal dissipation, the solution adds a dimensional aspect to heat management, effectively spreading thermal energy across a larger surface area.
2Area of stationary object
If chip size is reduced to meet demanding requirements, then device miniaturization is improved, but thermal management capability deteriorates
Solution Approach 1:
The patent makes the metallized areas serve dual functions: electrical connectivity and thermal radiation. By designing these areas to perform both functions simultaneously, the patent eliminates the need for separate thermal management structures, thereby maintaining effective heat dissipation capability while minimizing the overall chip area.
Solution Approach 2:
The patent enhances thermal management by strategically positioning and dimensioning metallized areas in specific locations where heat generation occurs. The metallized areas are designed with specific geometries and distributions that optimize local heat dissipation, allowing effective thermal management in a compact form factor.
3Power
If power saturation occurs at high power levels, then linear relationship between input and output power breaks down, but device reliability deteriorates
Solution Approach 1:
The patent implements thermal radiators and heat sinking structures in advance, before thermal damage can occur. By pre-positioning these thermal management features, the device is prepared to handle high power levels and prevent power saturation-induced thermal runaway, thereby maintaining reliability even at elevated power 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
The solution effectively minimizes hot spots and improves power compression performance, allowing for better heat distribution and preventing device damage under rapid power changes, maintaining performance similar to existing devices while enhancing thermal management.
Implementation Method 1
gradual increase of metal to wafer relation is made to provide better heat dissipation and heat sinking
Implementation Method 2
coupling of electromechanical energy to the piezo material
Implementation Method 3
first order DC resistance of the connection circuitry
Data Source
AI summary
This invention focuses on minimizing the hot spots on a filter chip by creating thermal radiators using the mechano-acoustic structures and connection circuitry. A gradual increase of metal to wafer relation is made to provide better heat dissipation and heat sinking. Preferably the shunt lines of the ladder type arrangement of SAW resonators (RS1, RS2, RS3) comprise a broadened section (BBCN). Each two series resonators (RS1, RS2, RS3) that are subsequent to each other in the series signal line are connected via a common busbar (BBCN) extending over a whole length of that subsequent series resonators, a lateral extension of the common busbars represents a first section of a respective shunt line each, each first shunt line section between a node and the parallel resonator (RP1, RP2) of a shunt line (SLS1) comprises a broadened section (BS) that is broader than the common busbar, the broadened section extends over the whole width of the parallel resonator (RP1), the first reflector (REF1) of the parallel resonator that faces the laterally adjacent series resonator is formed from the broadened section (BS).