HV Isolator Package With Silicon Block for Transformer Cooling
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Solution Overview
Problem
Isolated DC/DC converter packages face thermal dissipation limitations, restricting their ability to support high-power applications due to inadequate cooling, which is a challenge in medical, industrial, and aerospace sectors.
Innovation Solution
Incorporating a silicon block with magnetic sheets on either side of a laminate substrate under the transformer stack, attached via a thermally conductive adhesive, to enhance heat transfer from the transformer stack to a printed circuit board and ambient, thereby improving cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional MCM package with lateral IC die positioning is used, then the package structure is simple and easy to manufacture, but the thermal dissipation capability is insufficient for high-power applications
Solution Approach 1:
The patent transitions from a conventional lateral arrangement of IC die to a stacked three-dimensional configuration where the transformer is positioned vertically above the IC die. This vertical stacking enables direct thermal coupling between the transformer (hottest component) and the heat sink through a thermally conductive member, dramatically improving heat dissipation pathways without increasing lateral package footprint. The dimensional change from 2D lateral layout to 3D vertical stacking is the core innovation that resolves the thermal dissipation limitation.
2Ease of manufacture
If the transformer stack is positioned laterally adjacent to IC die, then electrical connections are easier to implement, but thermal resistance from junction to ambient increases
Solution Approach 1:
The patent introduces a thermally conductive member as an intermediary component positioned between the transformer stack and the heat sink. This intermediary provides a dedicated low-thermal-resistance pathway for heat flow from the transformer (the hottest component) directly to the heat sink, bypassing the higher thermal resistance paths through the mold compound and PCB. The thermally conductive member acts as a thermal bridge that resolves the thermal resistance issue while maintaining the electrical isolation benefits of the vertical stacking configuration.
3Power
If high-power applications are supported, then the power converter capability is improved, but thermal dissipation becomes insufficient without enhanced cooling
Solution Approach 1:
The patent merges multiple functions into the vertical stacked configuration: electrical isolation between primary and secondary sides through the transformer, mechanical support for the transformer above the IC die, and thermal management through direct coupling to the heat sink. This consolidation of electrical, mechanical, and thermal management functions into a single integrated three-dimensional structure enables high-power applications by simultaneously addressing power conversion capability and thermal dissipation requirements that cannot be achieved with separate conventional lateral arrangements.
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 configuration significantly reduces thermal resistance, enabling the isolated power converter package to operate at higher power levels by effectively dissipating heat, as demonstrated by a 26% reduction in thermal resistance from junction to ambient.
Implementation Method 1
The transformer stack being the hottest component in the isolated power converter package is physically attached generally by a thermally conductive adhesive material to the silicon block which is exposed from the mold compound at a bottom side of the isolated power converter package
Implementation Method 2
This silicon block under the transformer stack enables the heat from the transformer stack generated during operation to be spread through the silicon block, then to a thermal plane under the silicon block generally provided by a printed circuit board (PCB) that the isolated power converter package may be assembled onto, and finally to the ambient
Data Source
AI summary
A power converter package includes a leadframe including first and second die pads, and supports connected to first leads, and second leads. A first semiconductor die including first bond pads is on the first die pad, and a second semiconductor die including second bond pads is on the second die pad. A transformer stack includes a top magnetic sheet and a bottom magnetic sheet on respective sides of a laminate substrate that includes a coil within, and coil contacts. A silicon block is attached to the bottom magnetic sheet and edges of the laminate substrate are attached to the supports. Bond wires are between the first bond pads and the second leads, the second bond pads and the second leads, and the first and second bond pads and the coil contacts. Mold encapsulates the respective semiconductor and the transformer stack. A bottom of the silicon block is exposed from the mold.