Direct Laser Marking on SAW Substrates for Thinner Packages

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Solution Overview

Problem

There is a need for smaller and thinner packaged surface acoustic wave devices to accommodate increasing demands in semiconductor markets, particularly for applications requiring surface acoustic wave device package heights of 200 microns or less.

Innovation Solution

The development of packaged surface acoustic wave devices with a photosensitive buffer coat layer and direct laser marking on the piezoelectric substrate, which reduces the package height and eliminates the need for additional marking films, allowing for thinner profiles and lower packaging costs while maintaining electrical performance and structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If traditional packaging structures are used, then structural integrity and protection are ensured, but package height increases

Engineering Contradiction:

Improvepackage heightVSAvoidstructural integrity

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

The patent employs a thin photosensitive buffer coat layer (15 micrometers or less) as a protective film over the conductive structure, replacing traditional thick packaging materials. This thin film provides necessary protection while maintaining the reduced package height of 220 micrometers or less, directly resolving the contradiction between package height reduction and structural integrity maintenance.

Inventive Principle:

Principle #30Flexible shells and thin films

2Loss of information

If additional marking films are applied, then identification is improved, but package height and complexity increase

Engineering Contradiction:

Improveidentification capabilityVSAvoidpackage height

Core Design Contradiction:

Loss of informationVSLength of moving object

Solution Approach 1:

The patent combines the marking function directly into the piezoelectric substrate through laser marking, merging the identification capability with the existing substrate structure. This eliminates the need for separate marking films, maintaining identification capability while reducing package height and simplifying the overall structure.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces the mechanical application of marking films with laser marking technology. The laser directly marks the piezoelectric substrate without requiring additional film layers, substituting a thermal/optical process for a mechanical film application process, thereby reducing package height while maintaining identification capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If traditional packaging materials are used, then protection is ensured, but manufacturing cost increases

Engineering Contradiction:

Improveprotection capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent eliminates the need for separate marking films and traditional thick packaging materials by integrating protection functions into the photosensitive buffer coat layer and directly marking the substrate. This discarding of unnecessary components reduces material costs and simplifies the manufacturing process while maintaining protection capability.

Inventive Principle:

Principle #34Discarding and recovering

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 reduced height of less than 220 microns, achieving lower profile and cost-effective packaging while ensuring electrical performance and moldability strength, suitable for integration into smaller modules.

Implementation Method 1

a photosensitive buffer coat layer over the conductive structure

Methodology Applied

Scientific EffectPhotosensitivity: Photopolymerisation

Implementation Method 2

direct laser marking on the piezoelectric substrate

Methodology Applied

Scientific EffectLaser heating: Laser

Data Source

PatentUS11894824B2Laser-marked packaged surface acoustic wave devices

Publication Date: 2024.02.06 SKYWORKS SOLUTIONS INC

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.