Elastic Wave Device Sealing Resin Recessed Portion Thermal Stress
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Solution Overview
Problem
Elastic wave devices with recessed markings on sealing resin layers are prone to breakdown under thermal stress due to the formation of recessed portions, which can lead to mechanical weakness and failure.
Innovation Solution
Incorporating recessed portions on the sealing resin layer with a depth of at least one-third of the distance from the piezoelectric substrate's second main surface to the resin layer's surface, strategically located between bumps or outside the hollow portion, to reduce thermal stress and maintain mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a mark is inscribed on the upper surface of the sealing resin layer using a laser, then marking is achieved, but the inscribed portion becomes recessed and the device becomes prone to breakdown under thermal stress
Solution Approach 1:
The patent applies local quality by creating a recessed portion only in specific areas of the sealing resin layer where marking is needed, while maintaining the original surface structure in other areas. This localized modification allows marking functionality without compromising the overall structural integrity and thermal stress resistance of the device.
Solution Approach 2:
The patent implements beforehand cushioning by designing the recessed portion with specific depth constraints (no more than 1/3 of the distance from the second main surface of the piezoelectric substrate to the upper surface of the sealing resin layer). This pre-designed limitation cushions against potential breakdown by preventing the recess from being too deep, thereby maintaining sufficient structural strength to withstand thermal stress.
2Measurement precision
If the recessed portion depth is increased for better marking visibility, then marking quality improves, but mechanical strength decreases and thermal stress resistance worsens
Solution Approach 1:
The patent applies parameter changes by establishing a specific depth parameter for the recessed portion (no more than 1/3 of the distance from the second main surface of the piezoelectric substrate to the upper surface of the sealing resin layer). This parameter optimization balances marking visibility with mechanical strength, ensuring the recess is deep enough for clear marking but not so deep as to compromise structural integrity under thermal stress.
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 strategic placement and depth of recessed portions effectively reduce thermal stress on elastic wave devices, minimizing the likelihood of breakdown and maintaining mechanical strength, even under high temperatures.
Implementation Method 1
an elastic wave element including a piezoelectric substrate with first and second main surfaces opposite to each other and an interdigital transducer electrode provided on the first main surface of the piezoelectric substrate
Data Source
AI summary
An elastic wave device includes an elastic wave element mounted on a mounting substrate, with the elastic wave element being sealed by a sealing resin layer. The elastic wave element is bonded to electrode lands on the mounting substrate using bumps. Recessed portions are provided on a surface of the sealing resin layer on a side opposite to the side facing the mounting substrate. A ratio D/H between a depth of the recessed portions, and a distance of a portion of the sealing resin layer from the surface to a second main surface of a piezoelectric substrate, is no less than about 1/3.