Hanging Die Package Thermal Management via PCB Nesting
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Solution Overview
Problem
Legacy SiP implementations face thermal dissipation challenges due to the limited thickness of hanging dies, which restricts lateral heat dissipation and creates thermal bottlenecks, especially in mobile and IoT applications where form factor reduction is critical.
Innovation Solution
Increasing the thickness of the hanging die beyond the solder ball stand-off and thermally coupling its backside to a PCB cavity or heat spreader, using conductive pastes or gap pads for improved thermal conductivity, creating a new vertical heat dissipation path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness of the hanging die is increased beyond the solder ball stand-off, then thermal resistance is reduced and vertical heat dissipation is improved, but the device height increases
Solution Approach 1:
The hanging die is positioned within a recess or cavity formed in the PCB substrate. This nesting approach allows the die to extend vertically beyond the BGA matrix height while being contained within the PCB structure, reducing the overall device height increase despite the thicker die design
Solution Approach 2:
The patent transitions from traditional lateral heat dissipation to include vertical heat dissipation by extending the die thickness in the z-dimension. This creates a new thermal conduction path through the thickness of the die to the rear surface, where heat can be dissipated to the PCB and surrounding environment
2Temperature
If conductive pastes or gap pads are used to thermally couple the backside of the hanging die to the PCB cavity, then thermal conductivity is improved, but manufacturing complexity increases
Solution Approach 1:
Thermally conductive materials such as conductive pastes or gap pads are introduced as intermediary substances between the backside of the hanging die and the PCB cavity. These materials fill gaps and ensure intimate thermal contact, enabling efficient heat transfer from the die to the PCB substrate
Solution Approach 2:
The patent modifies thermal interface parameters by selecting appropriate conductive materials with optimized thermal conductivity properties. This allows tuning of the thermal coupling efficiency between the die and PCB, balancing thermal performance with manufacturing considerations
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
Significantly reduces thermal resistance and mitigates temperature hotspots by enhancing both lateral and vertical heat dissipation, improving the overall thermal management of package assemblies.
Implementation Method 1
thermally coupling its backside to a PCB cavity or heat spreader, using conductive pastes or gap pads for improved thermal conductivity
Data Source
AI summary
Embodiments herein generally relate to the field of package assembly to facilitate thermal conductivity. A package may have a hanging die, and attach to a printed circuit board (PCB). The package may have an active side plane and an inactive side plane opposite the first active side plane. The package may also have a ball grid array (BGA) matrix having a height determined by a distance of a furthest point of the BGA matrix from the active side plane of the package. The package may have a hanging die attached to the active side plane of the package, the hanging die having a z-height greater than the BGA matrix height. When package is attached to the PCB, the hanging die may fit into an area on the PCB that is recessed or has been cut away, and a thermal conductive material may connect the hanging die and the PCB.