Two-Layer Transformer Layout Without Bond-Wire Parasitics
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Solution Overview
Problem
Conventional isolation voltage converters using bond wires are large, expensive, and introduce parasitic inductance, reducing coupling efficiency and reliability due to the additional ringing on internal supply rails.
Innovation Solution
A two-layer transformer design with conductive segments and vias on a substrate eliminates the need for bond wires by directly coupling semiconductor dies to the transformer windings, reducing parasitic inductance and increasing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bond wires are used to couple semiconductor dies to transformer windings, then the conventional package structure is achieved, but parasitic inductance increases and coupling efficiency decreases
Solution Approach 1:
The patent removes bond wires from the system entirely by directly coupling semiconductor dies to transformer windings through a substrate. This extraction of the harmful element (bond wires) eliminates the source of parasitic inductance while maintaining the electrical connection function through alternative means (direct mounting structure).
Solution Approach 2:
The substrate serves as an intermediary structure that enables direct coupling between semiconductor dies and transformer windings. This mediator eliminates the need for bond wires while providing a stable mechanical and electrical connection platform, thereby reducing parasitic inductance without compromising connectivity.
2Ease of manufacture
If bond wires are used in the package, then the conventional structure is simpler to manufacture, but the package size increases and fabrication cost increases
Solution Approach 1:
The patent merges the semiconductor die mounting structure with the transformer structure by integrating both onto a common substrate. This consolidation eliminates the need for separate bond wire connections and reduces the overall package volume while maintaining manufacturability through a unified construction approach.
3Reliability
If bond wires are used to connect dies to leadframe, then the conventional package is achieved, but reliability over lifetime is reduced
Solution Approach 1:
The patent extracts bond wires from the package structure, eliminating the reliability issues associated with wire bonding such as fatigue, oxidation, and connection failures over time. The direct coupling approach provides more robust and stable connections that maintain reliability throughout the device lifetime.
Solution Approach 2:
The substrate-based direct coupling structure serves its own connection function without requiring additional bond wires. This self-sufficient design eliminates the need for separate bonding processes and components, reducing both complexity and potential failure points while improving overall package reliability.
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 two-layer transformer design enhances coupling efficiency and power efficiency by eliminating bond wires, resulting in a more compact and reliable isolation voltage converter.
Implementation Method 1
A transformer generally includes two conductive windings (also referred to as coils or inductors)—a 'primary' winding and a 'secondary' winding
Data Source
AI summary
An apparatus includes a substrate. A first conductive layer is on the substrate. The first conductive layer includes a first set of conductive segments and a second set of conductive segments. A second conductive layer is over the first conductive layer opposite the substrate. The second metal layer includes a third set of conductive segments and a fourth set of conductive segments. A first set of vias is between the first set of conductive segments and the third set of conductive segments. The first set of conductive segments, the third set of conductive segments, and the first set of vias form a first transformer winding. A second set of vias is between the second set of conductive segments and the fourth set of conductive segments. The second set of conductive segments, the fourth set of conductive segments, and the second set of vias form a second transformer winding.