Laser-Marked SAW Package Structure for Thinner Device Profiles
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Solution Overview
Problem
There is a demand for smaller and thinner packaged surface acoustic wave devices to fit into smaller modules while maintaining electrical performance and moldability strength, as existing packaging methods result in larger device sizes and higher costs.
Innovation Solution
The use of a photosensitive buffer coat layer and laser marking on a piezoelectric substrate to reduce the package height, eliminate the need for post structures, and integrate terminals directly with internal conductive structures, along with a spin-on process for insulation layers, to achieve a lower profile and lower cost packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional packaging methods are used, then the surface acoustic wave device is protected, but the device size increases and height exceeds 220 micrometers
Solution Approach 1:
The patent removes the photosensitive buffer coat layer from specific regions (edge portions and terminal regions) to eliminate unnecessary material that increases device height. This extraction reduces the overall package height to 220 micrometers or less while maintaining protection where the buffer coat layer remains over the cavity structure.
Solution Approach 2:
The patent transitions from a fully enclosed packaging structure to a partially open structure by selectively removing the buffer coat layer in specific dimensions and locations. This dimensional differentiation allows height reduction in certain areas while preserving protective functions in other areas.
2Reliability
If a photosensitive buffer coat layer is added for protection, then reliability improves, but device height increases
Solution Approach 1:
The patent applies the photosensitive buffer coat layer selectively - present over the cavity structure for protection, but absent from edge portions and terminal regions. This local differentiation maintains necessary protection while reducing overall package height to 220 micrometers or less.
Solution Approach 2:
Instead of applying the buffer coat layer completely, the patent uses partial action by limiting its presence to specific regions where protection is needed, thereby avoiding excessive height increase in areas where protection is not required.
3Reliability
If post structures are used to connect terminals, then electrical connection is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the post structures entirely by making edge portions of the piezoelectric substrate free from the buffer coat layer, allowing direct electrical connection between terminals and internal conductive structures without intermediate post elements.
Solution Approach 2:
The patent merges the terminal connection function directly with the substrate by creating direct physical contact between terminals and internal conductive structures through the removed buffer coat regions, eliminating the need for separate post structures.
4Loss of information
If laser marking is performed on the piezoelectric substrate, then identification is achieved, but substrate integrity may be compromised
Solution Approach 1:
The patent replaces traditional mechanical marking methods with laser marking, which achieves identification without the physical contact and potential damage associated with mechanical tools. The laser marking process creates permanent identification marks while preserving substrate integrity.
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 approach results in packaged surface acoustic wave devices with a height of less than 220 micrometers, reduced packaging costs, and meets electrical performance and moldability strength specifications, enabling integration into smaller modules.
Implementation Method 1
a photosensitive buffer coat layer over the conductive structure... The photosensitive buffer coat layer can include phenol resin. The photosensitive buffer coat layer can have a negative photosensitivity.
Implementation Method 2
a marking extending into the second side, the marking extending 1 micrometer or less into the piezoelectric substrate... a laser-marked piezoelectric substrate... the second side of the laser-marked piezoelectric substrate having a laser-marked section.
Implementation Method 3
a spin-on process for insulation layers
Data Source
AI summary
Laser-marked packaged surface acoustic wave devices are provided. The laser-marked packaged surface acoustic wave device may include a package structure encapsulating a surface acoustic wave device on a first side of a piezoelectric substrate. The opposite side of the piezoelectric substrate can be directly marked using a laser. The laser may be a deep ultraviolet laser. By directly marking the piezoelectric substrate itself, the use of a separate marking film can be avoided, making the packaged surface acoustic wave device thinner. When the laser has a wavelength readily absorbed by the piezoelectric substrate, a relatively shallow marking may be made in the piezoelectric substrate. The markings can extend less than 1 micrometer into the piezoelectric substrate, so as not to affect the structural integrity of the piezoelectric substrate or the operation of the packaged surface acoustic wave device.