Millimeter-Wave Package Ground Plane with Gas Venting Channels
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Solution Overview
Problem
Millimeter-wave packages face challenges in solderability and radio-frequency performance due to gas buildup during reflow, leading to void formation and heating issues, which conventional methods like breaking ground connections into subsections fail to adequately address at higher frequencies.
Innovation Solution
A laminate structure with a dielectric layer between conductive layers, featuring channels in the lower conductive layer to allow gas escape and maintain a continuous ground plane, enhancing solderability and radio-frequency properties while minimizing losses and ensuring robustness and manufacturability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large ground area connections are used, then radio-frequency grounding is improved, but solderability deteriorates due to gas buildup and void formation
Solution Approach 1:
The ground plane is segmented by forming channels through it, creating multiple pathways for gas escape while maintaining overall ground continuity. The channels divide the solid ground mass into regions that can vent gases during reflow, resolving the conflict between large ground area and solderability.
Solution Approach 2:
The ground plane is transformed into a porous structure with channels running through it, allowing gases to pass through during the soldering process. This porous configuration maintains electrical grounding functionality while enabling gas venting to prevent void formation.
2Ease of manufacture
If ground connections are broken into isolated subsections to allow gas escape, then solderability is improved, but radio-frequency grounding deteriorates at higher frequencies
Solution Approach 1:
Instead of breaking the ground plane into isolated subsections (2D segmentation), the invention extends channels through the ground plane in the third dimension. This maintains ground continuity in the lateral dimensions while providing vertical gas escape pathways, preserving RF grounding at high frequencies.
Solution Approach 2:
The channels act as intermediaries that allow gases to pass through the ground plane without breaking its electrical continuity. The ground plane remains intact laterally for RF grounding, while the channels provide a mediation pathway for gas escape during soldering.
3Ease of manufacture
If channels are formed through the ground plane, then solderability is improved by allowing gas escape, but device complexity increases
Solution Approach 1:
The channel formation process is merged with the existing ground plane fabrication process, integrating the gas escape pathways into the standard manufacturing flow. This reduces overall device complexity by combining multiple functions into a single structural element.
Data Source
AI summary
An apparatus includes a laminate and a lid. The laminate generally includes a dielectric layer between a first conductive layer and a second conductive layer. The first conductive layer may include a probe configured to transfer a radio-frequency signal in a millimeter-wave band. The second conductive layer may be configured to provide a continuous ground plane parallel to the probe and separated from the probe by the dielectric layer. A plurality of channels may be (a) formed into a side of the second conductive layer opposite the dielectric layer, (b) formed to a depth less than a thickness of the second conductive layer, and (c) sized to permit gasses formed while securing the laminate to a substrate to escape from between the laminate and the substrate. The lid may be in contact with the first conductive layer.