Functional Substrate Via Structure for Lower Thermal Stress
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Solution Overview
Problem
Traditional radio frequency chips in mobile phones face challenges with discrete devices having large volume, high power consumption, and inconsistent parasitic parameters, which are difficult to integrate and meet miniaturization and performance requirements, with Si-based chips having high microwave loss and GaAs-based chips being expensive.
Innovation Solution
A functional substrate with a dielectric substrate featuring connection holes with specific sub-holes and electrodes, designed to reduce thermal stress and improve integration, using a method that includes laser-induced etching and electroplating to form conductive structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If discrete devices are used on radio frequency PCB, then device functionality is achieved, but volume is large and integration is difficult
Solution Approach 1:
The patent merges multiple discrete devices (resistors, capacitors, inductors, filters) onto a single radio frequency integrated circuit substrate. This consolidation integrates previously separate components into one unified device, reducing overall volume and simplifying integration while maintaining all necessary functionalities for radio frequency operations
Solution Approach 2:
The integrated circuit substrate is designed to perform multiple functions simultaneously - it can contain resistive elements, capacitive elements, inductive elements, and filtering structures all on one substrate. This multi-functionality allows the single substrate to replace multiple discrete devices, achieving both volume reduction and functional integration
2Ease of manufacture
If Si-based integrated passive devices are used, then cost is reduced, but microwave loss increases due to poor insulation
Solution Approach 1:
The patent applies different material properties to different regions of the substrate - using silicon substrate for the base structure where cost is important, while implementing specific insulation layers and conductive patterns in critical areas to minimize microwave loss. The connection holes and electrodes are strategically designed to maintain signal integrity while leveraging the cost advantages of silicon
Solution Approach 2:
The patent creates a composite structure combining silicon substrate with additional insulating layers and conductive materials. This composite approach allows the device to benefit from the low cost of silicon while mitigating its poor insulation properties through the added layers, thereby reducing microwave loss without sacrificing cost effectiveness
3Reliability
If GaAs-based integrated passive devices are used, then performance is improved, but cost increases
Solution Approach 1:
The patent changes the material parameter from high-performance but expensive GaAs to cost-effective silicon, while compensating for the performance difference through optimized device geometry, connection hole design, and electrode configuration. This parameter change allows achieving acceptable performance at lower cost by relying on structural optimization rather than expensive materials
4Reliability
If connection holes are formed in dielectric substrate, then electrical connection is achieved, but thermal stress increases causing disconnection
Solution Approach 1:
The patent incorporates a relief structure (such as a chamfer or rounded corner) at the bottom of the connection hole before the electrode is fully formed. This pre-designed feature acts as a cushion that absorbs thermal stress during temperature cycling, preventing the stress from concentrating at the sharp corner and causing electrode disconnection, thereby protecting the connection reliability in advance
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 substrate design reduces thermal stress and improves reliability by minimizing disconnection risks, enabling efficient integration of passive devices with small area and high performance, suitable for miniaturized electronic devices.
Implementation Method 1
irradiating, by a laser, a position of the first dielectric substrate corresponding to the fully exposed region, and removing a material of the first dielectric substrate at the position corresponding to the fully exposed region to form the first connection hole
Implementation Method 2
forming a first connection electrode in the first connection hole
Data Source
AI summary
A functional substratincludes a first dielectric substrate, which includes a first surface and a second surface oppositely arranged along a thickness direction of the first dielectric substrate; the first dielectric substrate is provided with a first connection hole at least penetrating through the first surface; a first connection electrode is arranged in the first connection hole, whih includes a first sub-hole and a second sub-hole sequentially arranged along a direction away from the second surface and communicated with each other; the second sub-hole penetrates through the first surface; an opening width of the second sub-hole is monotonically increased in the direction away from the second surface, and a minimum opening width of the second sub-hole is not smaller than a maximum opening width of the first sub-hole; the first and second sub-holes form a corner at a position where the first sub-hole and the second sub-hole are connected.