Ceramic Package Via Conductor Corrosion Prevention
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Solution Overview
Problem
Hermetically-sealable ceramic packages face issues with metal corrosion when filled with liquid-containing electrolytes, leading to potential leaks and poor conduction due to corrosion of via conductors, which compromises the hermeticity and electrical connection.
Innovation Solution
A ceramic package design with a recessed cavity and via conductors connecting electrode pads to outer terminals, featuring an interlayer pad configuration where the pad body portion and interlayer pad portion have a protruding part, positioning the boundary at the interlayer surface between ceramic layers, which extends the electrolyte's path and prevents corrosion by maintaining close contact between ceramic layers, thus preventing electrolyte penetration to the via conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hermetically-sealable package structure is used with thin metal layers (nickel and gold) on inner electrodes, then the package can be manufactured with standard processes, but metal corrosion occurs when electrolyte contacts the inner electrode, leading to poor conduction and loss of hermeticity
Solution Approach 1:
The patent introduces a ceramic layer as an intermediary barrier between the electrolyte and the metal components. The via conductors pass through the ceramic layers rather than being directly exposed to electrolyte, mediating the connection while protecting the metal from corrosive environment. This resolves the contradiction by maintaining conduction integrity through the intermediary ceramic structure that prevents electrolyte contact with vulnerable metal surfaces.
Solution Approach 2:
The patent employs composite material structure combining ceramic and metal components. The package body uses ceramic layers (such as alumina) that are inherently resistant to electrolyte corrosion, while metal components are confined to protected areas. This composite approach maintains reliability by leveraging the corrosion-resistant properties of ceramic materials while retaining the conductive benefits of metal where protected from electrolyte exposure.
2Reliability
If via conductors are formed through ceramic layers to connect inner electrodes to outer terminals, then electrical connection is established, but electrolyte can penetrate to the via conductors causing corrosion and potential leaks
Solution Approach 1:
The patent implements a nested structure where via conductors are embedded within the ceramic layers. The conductors are nested inside the ceramic matrix, creating a protected pathway that maintains electrical connection while shielding the metal from electrolyte. This nesting approach resolves the contradiction by ensuring electrical connectivity through the via conductors while the surrounding ceramic provides protective enclosure against electrolyte penetration.
Solution Approach 2:
The patent uses thin ceramic films and layers to create protective barriers. The ceramic layers act as thin-film enclosures that conform to the via conductor structures, providing flexible yet effective protection against electrolyte while maintaining the necessary electrical pathways. This thin-film approach allows electrical connection through the via conductors while preventing electrolyte access to the metal surfaces.
3Adaptability or versatility
If the package cavity is filled with liquid electrolyte for battery or electrochemical cell application, then the desired electrochemical function is achieved, but corrosion of metallic conductive parts develops outwardly from the recessed cavity
Solution Approach 1:
The patent segments the package structure into distinct functional zones: an inner recessed cavity for electrochemical components filled with electrolyte, and outer protected regions where via conductors pass through ceramic layers. This segmentation isolates the electrolyte to its functional area while preventing corrosion propagation to external metal components. The ceramic layers act as segmentation barriers that contain the corrosive environment within the electrochemical cell functionality zone.
Solution Approach 2:
The patent applies preliminary protective measures by forming the via conductors to pass through the ceramic layers before final assembly and electrolyte filling. The ceramic structure is pre-configured to provide corrosion resistance pathways, preventing corrosion from developing outwardly from the recessed cavity. This preliminary anti-action is built into the structure design, ensuring that even when electrolyte is present, corrosion cannot propagate beyond the ceramic-protected zones.
Data Source
AI summary
Disclosed is a ceramic package for filling with a liquid-containing electrolyte, which includes: a package body defining a recessed cavity open at a front surface of the package body and including first and second ceramic layers stacked together; a plurality of electrode pads disposed on a bottom surface of the recessed cavity; and a plurality of outer connection terminals disposed on a back surface of the package body, wherein each of the electrode pads includes a pad body portion having a polygonal shape in plan view and an interlayer pad portion formed along an interlayer surface between the first and second ceramic layers, wherein the interlayer pad portion has a protruding part protruding outwardly from the pad body portion, and wherein via conductors are formed between the protruding parts of the electrode pads and the outer connection terminals through the first ceramic layer.