Through-Electrode Structure for Solder-Resistant Piezoelectric Resonators
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Piezoelectric resonator devices face issues with solder wetting and spreading inside through electrodes due to Au film corrosion, leading to increased conduction resistance and disconnection when mounted on external circuit boards.
Innovation Solution
The through electrodes in the piezoelectric resonator device are formed with a conductive metal other than Au, preventing solder corrosion and ensuring reliable conduction between internal and external electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a through electrode with Au film is used to establish conduction, then conduction reliability is improved, but solder corrosion causes Au agglomeration leading to increased conduction resistance and disconnection
Solution Approach 1:
The patent introduces a barrier metal layer (such as Ni or Pd) as an intermediary between the solder and the Au film in the through electrode structure. This barrier layer prevents direct contact between the solder and Au, thereby stopping the corrosion process while maintaining the excellent conduction properties of the Au film. The multi-layer structure acts as a mediator that protects the Au film from harmful solder interaction.
Solution Approach 2:
The through electrode is constructed as a composite structure with multiple metal layers (e.g., Cu core layer + Ni barrier layer + Au plating layer). Each layer serves a specific function: Cu provides cost-effective conduction, Ni provides corrosion resistance, and Au provides excellent conductivity and solderability. This composite material approach resolves the contradiction by combining materials with complementary properties.
2Ease of manufacture
If solder is used for mounting on external circuit board, then electrical connection is established, but solder spreads inside through electrode along Au film causing corrosion
Solution Approach 1:
The barrier metal layer serves as an intermediary that allows the solder to bond to the through electrode during mounting while preventing the solder from penetrating into and corroding the Au film. This mediator enables the manufacturing process to proceed normally while protecting the internal structure from damage.
Solution Approach 2:
The patent converts the potential harm of solder spread into a benefit by using the barrier layer to control and direct the solder flow. The solder can still perform its mounting function and provide electrical connection, but the barrier layer ensures that the solder spread is contained and does not reach the Au film, thus transforming a potentially harmful process into a controlled beneficial one.
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 configuration effectively prevents solder wetting and spreading, reducing the risk of increased conduction resistance and disconnection, thereby enhancing the reliability of the piezoelectric resonator device.
Implementation Method 1
a piezoelectric resonator plate (10) including a first excitation electrode (111) that is formed on a first main surface (101) of the substrate (10), and a second excitation electrode (112) that is formed on a second main surface (102) of the substrate and that makes a pair with the first excitation electrode
Data Source
AI summary
In a piezoelectric resonator device according to one or more embodiments, an internal space for hermetically sealing a vibrating part including a first excitation electrode and a second excitation electrode of a crystal resonator plate is formed by bonding a first sealing member and a second sealing member respectively to the crystal resonator plate. A through hole is formed in the second sealing member. A through electrode is formed along an inner wall surface of the through hole to establish conduction between an electrode formed on a first main surface and an external electrode terminal formed on a second main surface. A corrosion resistance structure to solder is formed on the through electrode that establishes conduction between the electrode and the external electrode terminal with a conductive metal other than Au.