Built-in Capacitor Substrate with Segmented Electrodes
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Solution Overview
Problem
Existing substrates with built-in capacitors face issues with electrode migration due to the use of conductive pastes containing glass components, especially when the distance between electrodes is less than 70 μm, leading to reduced reliability and potential scattering of potassium ions during vacuum lamination processes.
Innovation Solution
A substrate with a built-in multilayer ceramic capacitor featuring external electrodes formed from Ni or Cu pastes with a glass component in the range of 5-40%, which are connected to internal electrodes and covered with a copper plating film, reducing the risk of electrode migration by preventing potassium ion scattering during vacuum processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conductive paste containing glass component is used for external electrodes, then adhesion to internal electrodes is improved, but electrode migration occurs and potassium ions scatter during vacuum lamination
Solution Approach 1:
The external electrode is segmented into two distinct functional layers: a conductive paste layer (Ni or Cu paste with controlled glass content) for adhesion to internal electrodes, and a separate copper plated layer for structural stability and migration prevention. This segmentation allows each layer to optimize its specific function without compromising the other.
Solution Approach 2:
The glass component content in the Cu paste is precisely controlled within 5-40% to balance adhesion properties while preventing excessive potassium ion scattering. Additionally, the electrode separation distance is parameterized at 30-200 μm to maintain reliability while allowing compact design.
2Area of stationary object
If distance between external electrodes is reduced below 70 μm, then substrate integration density is improved, but electrode migration risk increases
Solution Approach 1:
The electrode separation distance is optimized to 30-200 μm, enabling high integration density while maintaining reliability. The copper plated layer thickness and composition are also adjusted to provide sufficient mechanical support at these reduced distances, preventing migration even in compact configurations.
Solution Approach 2:
The external electrode uses a composite structure combining conductive paste (with controlled glass content for adhesion) and copper plating (for structural integrity). This composite material approach allows electrodes to be placed closer together without increasing migration risk, as the copper layer provides mechanical stability.
3Reliability
If copper plated layer is added over conductive paste layer, then electrode migration is prevented, but manufacturing complexity increases
Solution Approach 1:
The formation of the copper plated layer is merged with existing plating processes in the manufacturing flow, utilizing standard copper deposition techniques already employed for other substrate features. This integration minimizes additional manufacturing complexity while achieving migration prevention.
Solution Approach 2:
The copper plated layer serves multiple functions simultaneously: it prevents electrode migration, provides electrical conductivity, enhances adhesion to the conductive paste layer, and offers corrosion resistance. This multi-functionality reduces the need for additional separate layers or 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 solution effectively reduces impedance in power source wiring by allowing multiple via conductors to connect to elongated electrodes while maintaining high adhesion and preventing migration, even at closer electrode distances, thereby enhancing the reliability and performance of the substrate with built-in capacitors.
Implementation Method 1
preventing potassium ion scattering during vacuum processing
Implementation Method 2
each of the external electrodes includes a conductive paste layer connected to a respective group of the internal electrodes
Data Source
AI summary
A substrate with a built-in capacitor includes an insulating base material layer, a build-up layer formed on the insulating base material layer and including a conductor layer and an insulating layer, and a multilayer ceramic capacitor positioned in an opening of the base material layer and including internal electrodes, ceramic dielectric layers and a pair of external electrodes. The ceramic capacitor has a cuboid shape having long sides and short sides, the pair of external electrodes is formed on opposing long-side sides such that the external electrodes are separated by a distance in range of 30 μm to 200 μm and that each external electrode includes a conductive paste layer connected to a respective group of the internal electrodes and a copper plated layer covering the conductive paste layer, and the conductive paste layer includes Ni paste or Cu paste including glass component in range of 5% to 40%.