A high-efficiency transformer-in-package isolated DC-DC converter using glass-based fan-out wafer-level packaging

Area of Science:

• Electrical Engineering
• Materials Science
• Semiconductor Packaging

Background:

• Traditional DC-DC converters often face limitations in size, cost, and efficiency due to discrete component integration.
• The integration of magnetic components, such as transformers, into semiconductor packages presents a significant challenge for miniaturization.

Purpose of the Study:

• To propose and demonstrate a transformer-in-package (TiP) isolated DC-DC converter.
• To leverage fan-out wafer-level packaging (FOWLP) for integrated transformer and interconnection fabrication.
• To achieve significant improvements in cost, form factor, power density, and efficiency.

Main Methods:

• Development of a TiP converter using a glass-based FOWLP with 3-layer redistribution layers (RDLs) for integrated transformer and interconnections.
• Fabrication of transmitter (TX) and receiver (RX) chips using a 0.18 µm Biopolar CMOS DMOS (BCD) process.
• Integration of TX and RX dies into a compact 5 mm × 5 mm package.

Main Results:

• The integrated transformer achieved high quality (Q) and coupling (k) factors, enhancing converter efficiency.
• The converter demonstrated a peak efficiency of 46.5% at 0.3 W output power.
• Achieved a maximum delivery power of 1.25 W and a maximum power density of 50 mW/mm².

Conclusions:

• The proposed TiP DC-DC converter effectively integrates a transformer within a FOWLP, reducing component count and cost.
• The solution offers substantial improvements in form factor and power density, suitable for space-constrained applications.
• The high-performance integrated transformer enables enhanced efficiency for miniaturized power conversion systems.