Laser-Drilled Stacked Circuit Package for Magnetic Isolation
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Solution Overview
Problem
Conventional stacked package technologies are inadequate for high power applications, as they fail to provide low impedance current paths, adequate thermal management, and sufficient magnetic isolation, leading to heat and voltage drop issues and magnetic coupling.
Innovation Solution
A stacked package structure is developed, where a bottom package with a substrate and circuitry is encapsulated in molded thermal plastic, with laser-drilled holes filled with conductive material, allowing an upper package to be precisely aligned and connected via solder or epoxy, ensuring electrical, thermal, and mechanical integrity, and magnetic isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional stacked package technology is used, then package size is reduced, but current path impedance increases and thermal management becomes inadequate
Solution Approach 1:
The package is divided into multiple segments (bottom package, intermediate package, top package) with each serving specific functions. The bottom package handles power switching, the intermediate package provides thermal management and magnetic isolation, and the top package handles signal processing. This segmentation allows optimized current paths in each layer while maintaining compact overall size.
Solution Approach 2:
The patent transitions from planar 2D package layout to 3D stacked architecture, utilizing vertical stacking to reduce footprint area. Multiple functional layers are arranged in the Z-dimension, enabling low-impedance current paths to extend vertically through dedicated power and ground planes in each layer, thereby maintaining electrical performance while minimizing package volume.
2Productivity
If conventional stacked package technology is used, then integration density increases, but thermal management becomes inadequate
Solution Approach 1:
An intermediate package layer is introduced as a mediator between the bottom power package and top signal package. This intermediate layer incorporates thermal vias, heat sinks, and thermal management structures that conduct heat away from high-power devices while providing mechanical support and electrical isolation, thereby enabling effective thermal management in high-density stacked configurations.
Solution Approach 2:
Different regions of the package are assigned different thermal management properties. High-power areas incorporate enhanced thermal conduction paths with thermal vias and heat sinks, while low-power signal areas use standard packaging. This localized approach optimizes thermal management where needed while maintaining integration density across the entire package.
3Productivity
If conventional stacked package technology is used, then component integration increases, but magnetic isolation becomes insufficient
Solution Approach 1:
The package is segmented into distinct functional blocks with the bottom package containing power switching components, the intermediate package providing magnetic shielding and isolation, and the top package containing sensitive signal components. This segmentation physically separates magnetic field sources from sensitive receivers, reducing magnetic coupling while maintaining high component integration through vertical stacking.
Solution Approach 2:
The intermediate package serves as a magnetic isolation intermediary, incorporating magnetic shielding materials and ground planes that block and redirect magnetic fields. This intermediate layer prevents magnetic coupling between the bottom power package and top signal package, enabling high component integration without compromising electromagnetic compatibility.
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 solution enables efficient heat transfer, minimizes voltage drop, and provides magnetic isolation, allowing for robust high-power switching regulators and other circuits with improved performance and reduced size.
Implementation Method 1
A programmed laser is then controlled to drill openings in the molded plastic which extend down to the metal pads on the substrate. The laser not only drills the holes but cleans the metal pads on the substrate.
Implementation Method 2
The holes are then partially filled with a solder, a solder paste, or other conductive material.
Implementation Method 3
provide good thermal paths to air and to a metal core printed circuit board
Data Source
AI summary
A stacked package configuration is described that includes a bottom package and an upper package. The bottom package includes a substrate having a top surface with first circuitry and metal first pads. A molded layer is then formed over the substrate. Holes through the molded layer are then laser drilled to expose the first pads. The holes and first pads align with leads of an upper package, which contains further circuit components. The holes are then partially filled with a solder paste. A thermal epoxy is applied between the molded layer and the upper package. The leads of the upper package are then inserted into the holes, and the solder paste is reflowed to electrically, thermally, and mechanically connect the upper package to the bottom package. The reflow heat also cures the epoxy. A ball grid array is then formed on the bottom of the substrate.