Liquid Ejecting Head Soldering Below Half the Piezoelectric Curie Point
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Solution Overview
Problem
Piezoelectric actuators in liquid ejecting apparatuses, such as inkjet printer heads, are prone to damage during mounting due to their fragility and the use of solder can lead to performance deterioration of the piezoelectric material when heated.
Innovation Solution
A liquid ejecting head design that uses a piezoelectric member with electrodes joined to a wiring substrate via solder with a melting point less than half the Curie point of the piezoelectric material, ensuring reliable mounting without deterioration, using lead-free solder with a suitable melting point to withstand operational temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is used to mount piezoelectric actuators, then mounting reliability is improved, but piezoelectric material performance deteriorates due to heating during mounting
Solution Approach 1:
The patent changes the parameter of solder melting point to resolve the contradiction. By selecting solder with a melting point of 100°C or lower (specifically 80-100°C range), the mounting process can proceed without excessive heating that would damage the piezoelectric material, while still achieving reliable mechanical and electrical connections through the low-melting-point solder's fluidity and strong bonding capability
2Object-affected harmful factors
If adhesive is used to mount piezoelectric actuators, then mounting process is gentle on fragile components, but mounting strength is insufficient for thin and fragile columnar elements
Solution Approach 1:
The patent changes the physical state and bonding mechanism of the mounting material from solid adhesive to low-melting-point solder. The solder's low melting point enables it to become fluid during mounting, allowing it to penetrate and bond strongly with thin and fragile columnar elements without requiring high mounting pressures that would damage the components
Solution Approach 2:
The patent replaces the mechanical bonding mechanism of adhesive with the thermal-melting mechanism of low-melting-point solder. The solder's unique property of melting at low temperatures (100°C or lower) allows it to transition from solid to liquid state during mounting, enabling strong bonding without the need for high-pressure mechanical attachment that would damage fragile piezoelectric actuators
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 prevents piezoelectric material deterioration and ensures reliable mounting by using solder with a melting point below half the Curie point, maintaining performance and avoiding connection failures.
Implementation Method 1
The solder has a melting point of less than or equal to 1/2 of the Curie point of the piezoelectric material
Implementation Method 2
A piezoelectric actuator using a piezoelectric material such as 'PZT' (lead zirconate titanate) can be used as driving source of a liquid ejecting apparatus
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A liquid ejecting head (1) includes a piezoelectric member, electrodes, and a wiring substrate (73). The piezoelectric member has a plurality of piezoelectric elements formed of a piezoelectric material. The electrodes are formed on the piezoelectric member. The wiring substrate is joined to the electrodes by solder. The solder has a melting point of less than or equal to 1/2 of the Curie point of the piezoelectric material.