Filter Chip Packaging Without Cap Wafer 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 film structure, then the film structure is protected from breakage, but the particle chip size cannot be miniaturized due to the requirement of cap wafer
Solution Approach 1:
The patent divides the packaging structure into individual chip-level units rather than maintaining a unified wafer-level structure. Each particle chip is packaged separately with its own protective housing, allowing the chips to be miniaturized independently without being constrained by wafer-level packaging requirements. This segmentation enables the removal of the cap wafer while still protecting the thin film structure through alternative packaging approaches at the chip level.
2Volume of moving object
If wafer-level thinning is performed to reduce chip size, then the particle chip size can be reduced, but the thin piezoelectric and electrode stack film structure is damaged due to pressure and shearing force
Solution Approach 1:
The patent performs protective packaging of individual filter chips onto substrates before the thinning process. By establishing this protective structure in advance, the thin film structure is shielded from the pressure and shearing forces that would occur during subsequent thinning operations. The packaging structure acts as a protective framework that allows thinning to proceed without damaging the delicate piezoelectric and electrode stack films.
3Reliability
If cap wafer is added for wafer-level packaging, then the film structure is protected, but the device complexity increases and miniaturization is hindered
Solution Approach 1:
The patent extracts and removes the cap wafer component from the packaging structure. By eliminating this unnecessary element, the invention simplifies the overall packaging structure while still achieving the required protection of the thin film structure through alternative means. This extraction reduces device complexity and enables miniaturization by removing the size constraint imposed by the cap wafer.
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
This method allows for the miniaturization of particle chips without damaging the fragile film structure, as the mold structure is thinned to a smaller thickness than the sum of the chip and substrate thicknesses, enabling precise cutting into smaller chips.
Implementation Method 1
a piezoelectric layer (114) disposed on the filter chip substrate (112)
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.