Filter Chip Packaging Cavity Structure for Smaller Particle Chips
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Solution Overview
Problem
The miniaturization of film bulk acoustic filter wafer-based particle chips is hindered by the need for wafer-level packaging, which can damage the thin piezoelectric and electrode stack film structure and limits size reduction due to the requirement of a cap wafer.
Innovation Solution
A chip packaging method involving flip-chip bonding of filter chips to a substrate, applying mold material layers to form a cavity, thinning the mold structure, and cutting it into particle chips, eliminating the need for wafer-level molding and cap wafer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wafer-level packaging is used to protect the thin piezoelectric and electrode stack film structure, then the film structure is protected from breakage and damage, but the particle chips cannot be miniaturized due to the requirement of cap wafer formation
Solution Approach 1:
The patent divides the packaging process into individual chip-level operations rather than wafer-level processing. Each filter chip is separately bonded to the substrate using flip-chip bonding, and individual mold layers are applied to each chip. This segmentation eliminates the need for a cap wafer covering the entire wafer, allowing each particle chip to be miniaturized independently while still protecting the thin film structure through localized molding.
2Volume of moving object
If wafer-level thinning is performed to reduce chip size, then the overall wafer thickness is reduced, but the thin piezoelectric and electrode stack film structure is subjected to pressure and shearing force causing breakage and damage
Solution Approach 1:
The patent applies the mold layer to the filter chip before thinning the substrate. This preliminary action creates a protective cavity structure that shields the thin piezoelectric and electrode stack film from the mechanical stress of subsequent substrate thinning operations. The mold layer is then thinned together with the substrate, but the film structure remains protected within the cavity throughout the process.
3Reliability
If cap wafer is added for wafer-level packaging, then the piezoelectric and electrode stack film structure is protected from damage, but the device complexity increases and miniaturization is hindered
Solution Approach 1:
The patent extracts and eliminates the cap wafer component from the packaging structure. Instead of adding a cap wafer to protect the film structure, the invention uses a substrate with a mold layer that forms a cavity to enclose and protect the filter chip. This removal of the cap wafer simplifies the overall packaging structure, reduces device complexity, and enables particle chip miniaturization while maintaining film structure protection through the alternative cavity-based approach.
Data Source
AI summary
A method for packaging chips includes: flip-chip bonding a plurality of filter chips to be packaged on a substrate to be packaged; applying a first mold material layer on the filter chips to be packaged; applying a second mold material layer on a side of the first mold material layer away from the filter chip to be packaged, the first mold material layer and the second mold material layer forming a first mold layer; thinning the first mold material layer and the second mold material layer to expose substrates of the filter chips to be packaged, and thinning the substrates of the filter chips to be packaged to a preset thickness; applying a second mold layer on the exposed substrates of the filter chips to be packaged to obtain a mold structure; and cutting the mold structure into a plurality of particle chips.