Wafer-Level Fabricated Tight-Coupling Dual-Solenoid Transformer Chips With Watt-Scale Power Transfer

Reported are a novel kind of tight-coupled dual-solenoid transformers (DSTs) which are on-chip integrated by using wafer-level fabrication including a low melting-point zinc-aluminum alloy rapid microcasting technique. Without magnetic core used, the silicon-chip integrated transformer is with the t...

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Bibliographic Details
Published in:IEEE transactions on power electronics 2023-04, Vol.38 (4), p.5118-5127
Main Authors: Chen, Changnan, Pan, Pichao, Lyu, Dongfeng, Gu, Jiebin, Liu, Min, Li, Xinxin
Format: Article
Language:English
Subjects:
Aluminum
Chip formation
Circuit faults
Coils
Coupling coefficients
Density
Heat treatment
High-frequency power components
Inductance
integrated transformers
Magnetic cores
Magnetic flux
Melting points
Metals
microcasting technique
Optimization
Power transfer
Power transformers
power/signal transmission
Resistance
Signal transmission
Solenoids
Transformers
wafer-level fabrication
Zinc base alloys
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Summary:Reported are a novel kind of tight-coupled dual-solenoid transformers (DSTs) which are on-chip integrated by using wafer-level fabrication including a low melting-point zinc-aluminum alloy rapid microcasting technique. Without magnetic core used, the silicon-chip integrated transformer is with the two metal solenoids tightly interwound to form a highly-coupled 3-D structure, thereby performing high inductance density and featuring no concern in magnetic flux saturation. Fabricated with the wafer-level thick-metal 3-D microcasting technique, the DST exhibits sufficient inductance value and low dc resistance while maintaining tiny footprint. Various DST structures are designed, fabricated and characterized for performance optimization. The optimally designed DST chip demonstrates a compact footprint of 2 mm 2 , a high inductance of 193.14 nH (i.e., inductance density = 96.57 nH/mm 2 ) and a small dc resistance of 1.09 Ω. The test shows that the chip achieves an ultrahigh coupling coefficient of 0.95 and superior maximum transformer efficiency of 87.8% at 100 MHz. More importantly, the DST achieves Watt -scale power transfer capability at 100 MHz, where no any heat dissipation treatment to the chip is used. Therefore, the on-chip DSTs are very promising for power/signal transmission in various electronic microsystems.
ISSN:0885-8993
1941-0107
DOI:10.1109/TPEL.2022.3231600