Cap Substrate Underside Marking for BAW Traceability
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Solution Overview
Problem
Existing acoustic wave devices, particularly bulk acoustic wave (BAW) filters, face challenges in traceability and identification, especially in small chip sizes, which complicates the management and quality control of these devices.
Innovation Solution
A BAW device package is designed with a cap substrate that has an underside marking layer, allowing for identification data to be marked on the underside of the cap substrate. This configuration enables traceability of the cap substrate, even in small chip sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If small chip sizes are used, then device integration and compactness are improved, but traceability and identification become difficult
Solution Approach 1:
The patent applies dimensionality change by moving the marking surface from the top face to the bottom surface of the cap substrate. This allows traceability information to be preserved on an otherwise unused surface area, enabling identification without increasing chip footprint. The marking layer is deposited on the bottom surface facing away from the acoustic wave device, effectively utilizing the third dimension (depth/thickness) to resolve the contradiction between small size and traceability.
2Loss of information
If marking is performed on the top surface, then identification is enabled, but interference with the acoustic wave device occurs
Solution Approach 1:
The patent segments the cap substrate into distinct functional surfaces: the top surface maintains acoustic wave device functionality while the bottom surface is dedicated to marking and traceability. This spatial segmentation allows identification data to be placed on the bottom surface without interfering with the acoustic wave device mounted on the top surface, resolving the contradiction between identification capability and device interference.
3Loss of information
If marking layer is added to the cap substrate, then traceability is improved, but manufacturing complexity increases
Solution Approach 1:
The marking layer is deposited on the bottom surface of the cap substrate during the manufacturing process before final assembly, when the substrate is still accessible and in a convenient state. This preliminary action integrates the marking step into the existing manufacturing flow without requiring additional post-assembly operations, thereby improving traceability while minimizing increases in manufacturing complexity.
Data Source
AI summary
A method for manufacturing a packaged acoustic wave component includes forming or providing a cap substrate, forming a metal layer on a surface of the cap substrate, marking the metal layer with one or more indicia and bonding the cap substrate to a device substrate that has an acoustic wave device on a surface thereof. The metal layer is paced from and faces the acoustic wave device.