Laminated Ceramic Component External Electrode Bondability
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Solution Overview
Problem
Laminated ceramic electronic components with external electrodes formed using conductive adhesives containing low-melting-point metals exhibit poor bondability to internal electrodes, particularly when the low-melting-point metal ratio is outside the optimal range, leading to metal ball deposition or eruption during heat treatment, which affects plating processes such as Ni plating.
Innovation Solution
A laminated ceramic electronic component with an external electrode featuring a conducting layer composed of a Cu3Sn alloy and a thermosetting resin, where the Sn content is between 36.5% to 47.8% of the total weight of Sn and Cu, promoting metal bonding with internal electrodes containing Ni, and suppressing metal ball deposition through the formation of a CuSnNi alloy phase with a solid solution of Ni between 5 atm % to 42 atm %, enhancing bondability and electrical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the blending ratio of low-melting-point metal is increased to improve bondability, then bondability improves, but metal ball deposition occurs during heat treatment
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Sn content within 36.5% to 47.8% by weight and Cu content within 52.2% to 63.5% by weight in the conducting layer. This specific compositional range ensures the Cu3Sn alloy forms with appropriate melting characteristics that enable reliable bondability while preventing metal ball deposition during subsequent heat treatment and plating processes.
Solution Approach 2:
The patent employs composite materials by creating a conducting layer that is a mixture of Cu and Sn metals forming a Cu3Sn alloy phase, combined with a thermosetting resin. This composite structure leverages the low-melting-point characteristics of the Cu3Sn alloy for effective bonding to internal electrodes while the thermosetting resin provides structural stability to prevent metal ball formation during heat treatment.
2Reliability
If heat treatment temperature is increased above 400°C to improve bondability, then bondability improves, but metal balls are deposited and plating failure occurs
Solution Approach 1:
The patent applies parameter changes by formulating the conducting layer with specific metal composition ratios (Sn: 36.5-47.8% by weight, Cu: 52.2-63.5% by weight) that create a Cu3Sn alloy with a melting point suitable for bonding at moderate temperatures. This allows achieving satisfactory bondability without exceeding 400°C heat treatment, thereby preventing metal ball deposition and ensuring plating quality.
Solution Approach 2:
The Cu3Sn alloy acts as an intermediary material between the external electrode and internal electrode. Its specific composition creates a eutectic structure with appropriate melting characteristics that facilitates bonding at controlled temperatures, mediating the heat transfer and preventing excessive temperature rise that would cause metal ball deposition.
3Reliability
If the Sn content is increased to improve bondability, then bondability improves, but the melting point decreases and remelting occurs during heat treatment
Solution Approach 1:
The patent applies parameter changes by optimizing the Sn content to 36.5-47.8% by weight, which is sufficient to form the Cu3Sn alloy phase for good bondability but controlled to prevent the melting point from dropping too low. This balanced composition achieves reliable bonding while maintaining thermal stability during subsequent heat treatment and plating 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 ensures satisfactory bondability between external and internal electrodes, suppresses metal ball deposition, and improves electrical characteristics and plating performance by generating a Cu3Sn alloy with a high melting point, preventing remelting during heat treatment and maintaining stable electrical properties.
Implementation Method 1
the conductive particles in the external electrode and the metal of the internal electrode are diffusion-bonded to each other
Implementation Method 2
the paste is held at 80 to 400° C. for 1 to 60 minutes for obtaining an external electrode
Implementation Method 3
particles (A) formed of a low-melting-point metal with a melting point of 300° C. or lower
Data Source
AI summary
A laminated ceramic electronic component that includes a laminated body formed by laminating a ceramic layer and an internal electrode; and an external electrode formed on an outer surface of the laminated body so as to be electrically connected to the internal electrode. The external electrode includes a conducting layer that is in contact with the internal electrode, and the internal electrode contains Ni. The conducting layer contains metal particles containing a Cu3Sn alloy, and a thermosetting resin. The metal particles contain Sn in a weight ratio of 36.5 to 47.8% to the total amount of Sn and Cu.