Ni-Bi Alloy Sealing Frame Bonding for Hermetic Electronic Devices
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Solution Overview
Problem
Existing methods for bonding sealing frames in electronic component devices, such as BAW filters, using Cu—Sn alloys are inefficient, requiring high temperatures and pressures, leading to low productivity and high costs, and are prone to defective sealing due to Kirkendall voids and oxidation issues.
Innovation Solution
The use of Ni films for the sealing frames with a Bi layer interposed between them, forming a Ni—Bi alloy bonding section, which has a faster growth rate and higher melting point than Cu3Sn, allowing for hermetic sealing with reduced thermal load and preventing Kirkendall voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cu—Sn alloy bonding is used for sealing frames, then bonding can be achieved, but high temperature and pressure are required leading to low productivity and high costs
Solution Approach 1:
The patent changes the material parameters by replacing Cu—Sn alloy with Ni—Bi alloy system. This material substitution fundamentally alters the bonding characteristics, enabling hermetic sealing at lower temperatures and pressures compared to conventional Cu—Sn bonding, thereby improving productivity while maintaining bonding reliability
Solution Approach 2:
The patent employs a composite structure consisting of Ni sealing frames with a Bi layer interlayer. This composite material system (Ni+Bi) creates a eutectic alloy bonding interface that combines the advantages of both materials: Ni provides structural integrity and oxidation resistance, while Bi enables low-temperature eutectic bonding, resolving the contradiction between bonding reliability and productivity
2Reliability
If Cu—Sn alloy bonding is used for sealing frames, then bonding can be achieved, but high costs are incurred
Solution Approach 1:
The patent changes the material composition parameters by adopting Ni—Bi alloy instead of Cu—Sn alloy. This parameter change reduces manufacturing costs through lower material and processing expenses while maintaining the hermetic sealing capability, thus resolving the contradiction between bonding reliability and manufacturing cost
3Reliability
If Cu—Sn alloy bonding is used for sealing frames, then bonding can be achieved, but Kirkendall voids and oxidation issues occur leading to defective sealing
Solution Approach 1:
The patent introduces a Bi layer as an intermediary between the Ni sealing frames. This Bi layer acts as a mediator that prevents direct Ni-Ni contact, eliminating the diffusion mismatch that causes Kirkendall voids. Additionally, the Bi layer serves as a protective barrier against oxidation, thereby resolving the harmful effects while maintaining sealing hermeticity
Solution Approach 2:
The Bi layer functions as a sacrificial consumable material during the bonding process. It is intentionally designed to be consumed (diffuse into Ni) during bonding to prevent harmful effects, and its lower cost compared to alternative protective layers makes this approach economically viable while ensuring sealing quality
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 enables rapid bonding with lower production costs, improved hermeticity, and resistance to plastic fatigue failure, while maintaining device integrity through the Ni—Bi alloy's high melting point and efficient diffusion process.
Implementation Method 1
forming a Ni—Bi alloy bonding section, which has a faster growth rate
Implementation Method 2
heating the first and second sealing frames with a Bi layer predominantly composed of Bi interposed between the first sealing frame and the second sealing frame
Data Source
AI summary
An electronic component device having a first sealing frame formed on a main substrate and a second sealing frame formed on a cover substrate, the first and second sealing frames being composed of a Ni film. A bonding section constituted by a Ni—Bi alloy is formed between the first and second sealing frames. For example, a Bi layer is formed on the first sealing frame, and then the first sealing frame and the second sealing frame are heated at a temperature of 300° C. for at least 10 seconds while applying pressure in the direction in which the first sealing frame and the second sealing frame are in close contact with each other, and thus the bonding section, which bonds the first sealing frame to the second sealing frame, is formed.