Cu Plating Recrystallization for Electronic Device Electrode Reliability
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Solution Overview
Problem
Existing electronic devices face issues with the entry of plating solutions and moisture due to minute voids in external electrode layers, leading to defects such as 'glass scum' and solder popping, which compromise reliability.
Innovation Solution
A method involving a Cu-baked electrode layer, a Cu plating layer processed by recrystallization treatment, and at least one upper-side plating layer, where a conductive paste with glass and Cu powder is applied, baked, and then subjected to a heat treatment to recrystallize the Cu plating layer, preventing the entry of plating solutions and moisture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Cu-baked electrode layer is densified by baking to prevent entry of plating solution and moisture, then the reliability is improved, but glass moves up to the surface and precipitates causing plating defects and solder popping
Solution Approach 1:
The patent applies a recrystallization treatment to the Cu plating layer at controlled temperatures and times to densify the structure and eliminate voids without causing glass precipitation. This thermal parameter control resolves the contradiction by achieving densification through a different mechanism (recrystallization) rather than excessive baking that causes glass to migrate to the surface.
Solution Approach 2:
The patent uses a multi-layer composite structure consisting of Cu-baked electrode layer, Cu plating layer, Ni plating layer, and Sn plating layer. Each layer serves specific functions: the Cu-baked layer provides adhesion and conductivity, the Cu plating layer provides dense barrier properties after recrystallization, the Ni layer prevents solder dissolution, and the Sn layer improves solder wettability. This composite approach allows achieving both reliability and manufacturing precision.
2Ease of operation
If a three-layered structure (Cu-baked electrode layer, Ni plating layer, Sn plating layer) is used to prevent dissolution and improve solder wettability, then the solderability is improved, but minute voids in Ni plating layer allow entry of plating solution and moisture
Solution Approach 1:
The patent segments the protective function into two distinct layers: the Cu plating layer (added between Cu-baked and Ni layers) provides the primary barrier against plating solution and moisture entry through its dense recrystallized structure, while the Ni and Sn layers maintain their specialized functions of preventing solder dissolution and improving wettability respectively. This segmentation allows each layer to optimize its specific function without compromising others.
Solution Approach 2:
The Cu plating layer acts as an intermediary barrier layer between the Cu-baked electrode layer and the Ni plating layer. This intermediate layer provides a dense barrier function that prevents plating solution and moisture from reaching the Ni layer through voids, while still allowing the Ni layer to perform its solder protection function. The intermediary layer thus protects the entire structure from environmental degradation.
3Object-affected harmful factors
If the Ni plating layer is used as an inter layer to prevent entry of plating solution, then the corrosion resistance is improved, but minute voids reduce the effectiveness of this protective function
Solution Approach 1:
The patent applies recrystallization treatment to the Cu plating layer before forming the Ni and Sn plating layers. This preliminary densification of the Cu layer creates a solid barrier that prevents plating solution and moisture from penetrating through to the Ni layer during subsequent plating and soldering processes. The preliminary action ensures that the Ni layer's protective function is not compromised by environmental degradation from the start.
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
This approach results in a highly reliable electronic device with a dense Cu plating layer that prevents plating solution and moisture ingress, reducing defects like plating and solder popping, and maintaining internal electrode integrity.
Implementation Method 1
a Cu plating layer which is formed on the Cu-baked electrode layer and which is processed by a recrystallization treatment
Implementation Method 2
a conductive paste with glass and Cu powder is applied, baked
Data Source
AI summary
A highly reliable electronic device that prevents entry of a plating solution via an external electrode and entry of moisture of external environment inside thereof, and generates no soldering defects or solder popping defects which are caused by precipitation of a glass component on a surface of the external electrode. The electrode structure of the electronic device is formed of Cu-baked electrode layers primarily composed of Cu, Cu plating layers formed on the Cu-baked electrode layers and which are processed by a recrystallization treatment, and upper-side plating layers formed on the Cu plating layers. After the Cu plating layers are formed, a heat treatment is performed at a temperature in the range of a temperature at which the Cu plating layers are recrystallized to a temperature at which glass contained in a conductive paste is not softened, so that the Cu plating layers are recrystallized.