Varistor Layer Integration in Ceramic Component Carriers
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Solution Overview
Problem
Existing component carriers face challenges in integrating a protective function while maintaining a small design and improved thermal conductivity, particularly in dissipating overvoltage pulses and electrostatic discharge (ESD) without increasing volume or damaging varistor layers during production.
Innovation Solution
A component carrier with a ceramic main body featuring plated-through holes, a varistor layer applied above an electrode pair, and a second electrode pair connected in parallel, allowing for efficient ESD dissipation and improved thermal conductivity through the use of materials like aluminum nitride, with optional internal electrodes and passivation layers for enhanced protection and manufacturing flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a varistor is integrated into a component carrier, then ESD protection function is provided, but the component carrier volume increases
Solution Approach 1:
The patent combines the varistor layer directly with the component carrier substrate, integrating the ESD protection function into the carrier itself rather than adding it as a separate discrete component. This merging approach provides ESD protection while minimizing volume increase.
Solution Approach 2:
The varistor layer is positioned within the component carrier structure, nested between the first and second electrode pairs that are already part of the carrier's electrical architecture. This nesting allows the protection function to be embedded without significantly increasing overall volume.
2Area of stationary object
If the varistor layer is laterally dimensioned close to the edges, then placement area is maximized, but the varistor layer is exposed to mechanical influences
Solution Approach 1:
The patent applies different lateral dimensions to the varistor layer compared to the electrode pairs, creating a protective margin around the varistor. This local dimensional adjustment protects the varistor from mechanical influences while maintaining adequate placement area for electrical components.
3Temperature
If aluminum nitride is used for the main body, then thermal conductivity is improved, but material cost increases
Solution Approach 1:
The patent specifies aluminum nitride as the material for the component carrier main body, changing the material parameter to achieve superior thermal conductivity. This parameter change enables more efficient heat dissipation from mounted components, particularly important for high-power applications.
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 effective ESD protection with minimal volume increase, improved thermal conductivity, and reduced risk of varistor damage during production, allowing for the integration of ESD protection into a compact component carrier that can handle higher currents and overvoltages.
Implementation Method 1
Varistors are nonlinear components whose resistance decreases greatly when a specific applied voltage is exceeded. Varistors are therefore suitable for harmlessly dissipating overvoltage pulses.
Implementation Method 2
Electrical terminal pads and first electrode pair are electrically connected to one another via plated-through holes.
Implementation Method 3
improved thermal conductivity through the use of materials like aluminum nitride
Data Source
AI summary
A green film composed of varistor material laminated on a ceramic main body, which is provided with metallizations on both sides, and is sintered to form a varistor layer. A terminating electrode pair completes the arrangement and allows the varistor layer to be operated as a varistor. The upper second electrode pair can serve directly as a terminal contact for mounting an electrical component.