Thin Dielectric Substrate for Low Thermal Resistance and Inductance
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Solution Overview
Problem
Existing substrates used in the IC packaging industry face challenges in achieving low thermal resistance and low parasitic inductance, particularly when heat and electrical current flow vertically through VCSEL chips, leading to degraded performance in high-speed signal quality and heat dissipation.
Innovation Solution
A substrate design featuring a ceramic core with metal-filled vias and thin dielectric layers made from materials like aluminum oxynitride (AlON), aluminum phosphate (AlPO4), or aluminum oxide (Al2O3) with thicknesses ranging from 0.01 µm to 60 µm, separating metal layers to reduce parasitic inductance and thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin dielectric layer is used to reduce parasitic inductance, then high-speed signal quality is improved, but thermal resistance may increase
Solution Approach 1:
The patent employs a composite dielectric layer combining aluminum oxynitride (AlON) and aluminum phosphate (AlPO4) materials. The AlON layer provides low dielectric constant for reduced parasitic inductance, while the AlPO4 layer contributes to thermal management. This composite structure resolves the contradiction by integrating materials with complementary properties that simultaneously address both electrical performance and thermal dissipation requirements.
2Temperature
If a thick dielectric layer is used to improve thermal resistance, then heat dissipation is improved, but parasitic inductance increases
Solution Approach 1:
The multi-layer composite dielectric structure allows optimization of each layer's thickness for its specific function. The AlPO4 layer can be made thicker to improve thermal conduction, while the AlON layer maintains electrical performance with appropriate thickness, achieving both heat dissipation and low parasitic inductance simultaneously.
Solution Approach 2:
Different regions of the dielectric structure have different thicknesses and material compositions optimized for local requirements. Areas requiring thermal management have thicker high-thermal-conductivity layers, while areas requiring electrical performance have optimized thin layers, resolving the global contradiction through local optimization.
3Ease of manufacture
If conventional dielectric materials are used, then manufacturing is simpler, but both thermal resistance and parasitic inductance are high
Solution Approach 1:
The patent changes the material parameters by selecting AlON and AlPO4 with specific physical and electrical properties. These material parameter changes enable simultaneous achievement of low thermal resistance and low parasitic inductance, overcoming the limitations of conventional dielectric materials while maintaining compatibility with existing manufacturing processes.
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 thin dielectric layers significantly reduce parasitic inductance and thermal resistance, enhancing heat dissipation and high-speed signal quality, making the substrate suitable for high-power VCSEL-based applications such as ToF camera projector modules.
Implementation Method 1
a thin dielectric layer on the first metal layer, wherein the thin dielectric layer has a low thermal resistance based on one or more of the thickness of the thin dielectric layer or a material used for the thin dielectric layer
Implementation Method 2
a thin dielectric layer on the first metal layer... a second metal layer, on the thin dielectric layer, including: a first electrical contact over the first metal trace and electrically isolated from the first metal trace
Data Source
AI summary
In some implementations, a substrate comprises a ceramic core, multiple metal-filled vias through the ceramic core, and a first metal layer, on a top side of the ceramic core, including metal traces, over respective metal-filled vias. The substrate comprises a second metal layer, including a first electrical contact over a first metal trace, a second electrical contact over a second metal trace, and a third electrical contact over a third metal trace, where the second metal trace is electrically isolated from the first and third metal traces. The substrate comprises a thin dielectric layer separating the first metal layer and the second metal layer. The dielectric layer between the first metal layer and the second layer provides the substrate with a low parasitic inductance and a low thermal resistance based on a thickness of the dielectric layer and/or a material used for the dielectric layer.