Garnet Ferrite Composition for Silver Co-Sintering at Lower Temperatures
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Solution Overview
Problem
The production of microwave circulators and isolators is hindered by high costs and complexity due to lengthy assembly processes and the inability to co-sinter ferrite materials with silver, which degrades performance and lifespan.
Innovation Solution
A new ferrite material with a lithium-based flux is introduced, characterized by the chemical formula (1-x)(Y a TR b Bi b , Fe c Al d In e Ca f Cu g Zr h Co i Si j O 12±γ ) + x (Li 2 CO 3 or Li 2 O or LiF or LiCI), allowing for sintering at lower temperatures and enabling co-sintering with silver, thus simplifying the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional YIG ferrite material is used, then good microwave performance is achieved, but high sintering temperature (1450-1500°C) prevents co-sintering with silver or gold metallization
Solution Approach 1:
The invention modifies the chemical composition parameters of the ferrite material by substituting iron with cobalt and incorporating specific rare earth elements (Nd, Sm, Eu, Gd) in controlled amounts. This compositional parameter change reduces the sintering temperature from 1450-1500°C to a range compatible with silver and gold metallization (below 1064°C and 962°C respectively), while maintaining microwave performance through optimized magnetic properties.
Solution Approach 2:
The invention creates a composite ferrite material system combining multiple elements (Y, Co, Fe, O, Nd, Sm, Eu, Gd) in a garnet structure. This multi-element composite approach allows tuning of both sintering temperature and microwave characteristics, achieving compatibility with low-melting-point metals while preserving the non-reciprocal microwave functionality required for circulators and isolators.
2Ease of manufacture
If mechanical assembly of components is used, then device construction is achieved, but production cost and complexity increase
Solution Approach 1:
The invention merges the ferrite component and metallization layers into a single co-sintered structure. By reducing the ferrite sintering temperature to be compatible with silver and gold, all components are simultaneously sintered in one process step, eliminating separate assembly operations, adhesive application, and multiple firing cycles, thus simplifying manufacturing and reducing complexity.
3Ease of manufacture
If adhesive is used to bond components, then assembly is achieved, but device performance and lifespan are degraded
Solution Approach 1:
The invention extracts and eliminates the adhesive bonding step from the manufacturing process. By achieving direct co-sintering between ferrite and metallization through temperature-compatible material composition, the need for organic adhesives is removed, preventing performance degradation from adhesive interference with microwave fields and eliminating long-term reliability issues from adhesive aging and delamination.
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 reduces production costs and complexity by allowing co-sintering with silver, overcoming previous temperature compatibility issues and maintaining the integrity of the metallic pattern, thereby enhancing the durability and performance of microwave circulators and isolators.
Implementation Method 1
a sintering operation is carried out during which the ferrite is bonded to at least one of the other elements of the component or to a precursor (gold or silver metal, low sintering temperature dielectric, low sintering temperature ferrite ...) of the element by a co-sintering process
Implementation Method 2
A ferrite material particularly well suited to the applications referred to in the present invention and in particular for applications in the frequency range [1GHz, 12GHz] is a ferrimagnetic yttrium iron garnet (YIG)
Data Source
Figure 1~2b
Figure 3a~3b
Figure 4~5
AI summary
The invention relates to a ferrite material characterized in that it corresponds to the following chemical formula: (1-x) (YaTRbBib,FecAldIneCafCugZrhCOiSijO12±γ + x (Li2CO3 or Li2O or LiF or LiCl) with x mass% between 0.1 and 2, where TR is a rare earth element or a combination of rare earth elements not comprising the element Y -1 ≤γ≤ 1; 3 (a+b+b'+c+d+e) + 2 (f+g+i) + 4 (h+j) = 24±2γ 0 ≤ a ≤ 2; 0 ≤ b ≤ 1.5; 0.1 < b' < 3; 4 ≤ c ≤ 5; 0 ≤ d ≤ 1.5; 0 ≤ e ≤ 0.8; 0 ≤ f ≤ 1; 0 < g < 0.05; 0 ≤ h ≤ 1; 0 ≤ i ≤ 0.5; 0 ≤ j ≤ 0.5. The invention also relates to a method for manufacturing the ferrite material of the invention.