Air Cavity Semiconductor Packaging via Molding Compound and Single Cover
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Solution Overview
Problem
Conventional air cavity packaging methods face challenges such as the need for individual lid placement, limitations in dimensional shrinking, and multiple process steps, making it difficult to fabricate small packages and requiring separate formation and mounting.
Innovation Solution
A method involving a carrier with multiple device regions and contact pads on an etchable substrate, where semiconductor dies are attached and electrically connected, and a molding compound is applied to define air cavities, allowing for simultaneous formation and encapsulation of multiple die packages with a single cover, enabling efficient singulation into individual packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional air cavity packaging methods are used with individual lid placement, then each package can be sealed, but the process steps increase and productivity decreases
Solution Approach 1:
Multiple individual air cavity packages are merged into a single array structure on one carrier. Multiple lids are combined into a single lid assembly that simultaneously seals multiple cavities. This merging reduces the number of separate sealing operations from many individual lid placements to one collective sealing action, dramatically improving productivity while maintaining reliable sealing for each package.
Solution Approach 2:
Multiple semiconductor dies are pre-mounted on the carrier in an array configuration before the air cavity formation and sealing processes. The carrier itself is prepared with multiple device regions and contact pads in advance. This preliminary arrangement allows subsequent processing steps to handle multiple packages simultaneously, reducing total process steps and improving fabrication efficiency.
2Ease of operation
If conventional air cavity packages are formed separately and then mounted, then each package can be individually handled, but the process steps increase and dimensional shrinking is limited
Solution Approach 1:
The carrier is divided into multiple discrete device regions, each capable of holding and processing a single semiconductor die independently. After the array is sealed and processed, the carrier can be singulated into individual packages. This segmentation allows each package to be independently handled and tested while enabling batch processing during fabrication, reducing overall process complexity.
Solution Approach 2:
Multiple packaging operations that would traditionally be performed separately on individual packages are merged into simultaneous batch operations on the array. The single lid assembly seals multiple cavities at once, and the molding compound encapsulates multiple packages simultaneously. This merging reduces the total number of process steps while maintaining the ability to handle individual packages after singulation.
3Productivity
If multiple die packages are fabricated simultaneously on one carrier, then productivity increases, but the carrier design and process complexity increase
Solution Approach 1:
The carrier is designed as a multi-functional platform that simultaneously performs multiple functions: it serves as the mounting substrate for multiple semiconductor dies, provides structural support for the air cavity array, enables electrical interconnections through shared contact pads, and facilitates batch processing through its array configuration. This universal design achieves high productivity without proportionally increasing complexity, as the same structural elements serve multiple purposes.
Solution Approach 2:
Different regions of the carrier are optimized for specific functions: device regions are designed with specific contact pad arrangements for electrical connections, air cavity regions are shaped and positioned for optimal sealing and dielectric performance, and the overall array layout is configured for efficient batch processing. This localized optimization allows complex multi-package fabrication without requiring the entire carrier to be overly complex.
4Reliability
If air cavities are sealed with lids, then environmental protection is provided, but the process steps and manufacturing complexity increase
Solution Approach 1:
Multiple individual sealing operations are merged into a single collective sealing process. The lid assembly is designed to simultaneously seal multiple air cavities in one operation, reducing manufacturing complexity from many separate sealing steps to one batch sealing process. This maintains reliable environmental protection for each package while dramatically simplifying the manufacturing process.
Solution Approach 2:
The lid assembly is pre-configured with sealing surfaces and attachment features that correspond to the array of air cavities before the sealing process. This preliminary preparation allows the sealing operation to proceed in a single step without requiring complex alignment or sequential operations, maintaining reliable sealing while simplifying manufacturing.
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 approach allows for the simultaneous fabrication of multiple air cavity and non-air cavity die packages in a compact, smaller format, reducing process steps and enabling easier handling, while maintaining the benefits of air cavity packaging for high-frequency semiconductor chips.
Implementation Method 1
Dry air has a considerably lower dielectric constant than molding compounds, which improves electrical performance of the high frequency semiconductor chip
Implementation Method 2
a body of a molding compound is applied on the carrier that defines an air cavity disposed about another device region and encapsulates the first device region and the first semiconductor die. Each of a plurality of different semiconductor die is attached inside each of the air cavities and is electrically coupled with the surfaces of contact pads, which are exposed inside each of the air cavities. The etchable substrate is etched to define contact surfaces accessible from a location external to the body of molding compound for each of the contact pads
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A die package (72) for a semiconductor die (20). A plurality of the die packages (72) are formed on a single carrier (10) by applying a body (55) of molding compound across a carrier (10) with an air cavity (70) defined in the molding compound about each of a plurality of device regions (12) of the carrier (10). After a semiconductor die (20) is attached inside the air cavity (70) of each device region (12) and electrically connected with at least one contact pad (14, 16, 18), a cover (68) is applied to close all of the air cavities (70). Following singulation, each semiconductor die (20) is located inside the sealed air cavity (70) of one die package (72). The molding compound of each die package (72) may be locked against movement relative to the device region (12) of the carrier (10) by locking features (30, 38, 48, 50). The locking features (30, 38, 48, 50) may constitute portions of contact pads (14, 16, 18) used to establish electrical communication paths from the semiconductor die (20) to the environment outside of the package (72).