Monolithic LTCC Seal Frame and Lid Cofiring
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Solution Overview
Problem
Traditional microelectronic packaging using metal seal frames and lids with ceramic substrates face reliability issues due to thermal expansion mismatches, leading to degradation or failure under temperature swings, and previous attempts to form ceramic seal frames and lids are labor-intensive with alignment and dimensional control difficulties.
Innovation Solution
A method for forming a monolithic ceramic and glass-based seal frame and lid using a mandrel, where the mandrel is formed from ceramic and glass material, and the seal frame and lid are created by routing and cofiring ceramic and glass material to match the substrate, with optional metal coating for bonding and EMI shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal seal frames and lids are used with ceramic substrates, then the manufacturing process is simplified, but thermal expansion mismatch causes reliability degradation under temperature swings
Solution Approach 1:
The patent applies homogeneity by using the same ceramic material for both the substrate and the seal frame/lid assembly. This ensures matching thermal expansion coefficients (CTE) between the substrate and the seal frame, eliminating the reliability issues caused by CTE mismatch that occur with metal seal frames. The ceramic seal frame is formed from the same or compatible ceramic material as the LTCC substrate, creating a homogeneous structure that expands and contracts uniformly during temperature cycles.
Solution Approach 2:
The patent uses composite materials by combining ceramic and glass-based materials to form the seal frame and lid. This composite approach allows optimization of both mechanical properties and thermal expansion characteristics to match the substrate. The cofired ceramic-glass composite structure provides both the manufacturability of a single-process approach and the thermal compatibility needed for reliable operation under temperature swings.
2Reliability
If ceramic seal frames and lids are formed using traditional methods, then thermal expansion mismatch is reduced, but the process becomes labor intensive with alignment and dimensional control difficulties
Solution Approach 1:
The patent merges the formation of the seal frame and lid into a single integrated component formed from a single block of ceramic and glass material. This eliminates the need for separate formation, alignment, and assembly operations that characterize traditional methods. The mandrel-based approach allows the entire seal frame/lid assembly to be formed in one cofiring process, significantly reducing labor intensity and improving dimensional control while maintaining thermal expansion compatibility.
Solution Approach 2:
The patent introduces a mandrel as an intermediary tool that simplifies the formation of the ceramic seal frame and lid. The mandrel serves as a mold or pattern around which the ceramic and glass material is shaped and cofired. This intermediary approach enables precise dimensional control and alignment without requiring complex manual operations, resolving the contradiction between achieving good thermal match and maintaining manufacturing simplicity.
3Manufacturing precision
If a mandrel is used to form the seal frame and lid block, then alignment and dimensional control are improved, but an additional manufacturing step is introduced
Solution Approach 1:
The mandrel is prepared in advance as a pre-formed pattern or mold that defines the desired geometry of the seal frame and lid. By performing the alignment and dimensional definition work beforehand in the mandrel preparation stage, the actual cofiring process benefits from pre-established precision without requiring complex real-time adjustments. This preliminary action approach improves manufacturing precision while keeping the overall process manageable.
Solution Approach 2:
The mandrel serves as a physical copy or pattern of the desired seal frame and lid geometry. The ceramic and glass material is formed by copying the mandrel's shape and dimensions during the cofiring process. This copying approach transfers the precision of the mandrel (which can be manufactured with high accuracy) to the final ceramic component, achieving excellent dimensional control without requiring complex measurement and adjustment operations during assembly.
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 enhances the reliability of microelectronic packaging by aligning thermal expansion coefficients and simplifying the manufacturing process, reducing labor intensity and improving long-term reliability by using a monolithic ceramic and glass-based seal frame and lid that matches the substrate, while providing EMI shielding.
Implementation Method 1
cofiring the seal frame and lid block
Implementation Method 2
coating at least a portion of the upper surface of the mandrel with a high-temperature lubricant
Implementation Method 3
optional metal coating for attachment and EMI shielding
Data Source
AI summary
A method for forming a monolithic seal frame and lid for use with a substrate and electronic circuitry comprises the steps of forming a mandrel from a ceramic and glass based material, forming a seal frame and lid block from a ceramic and glass based material, creating a seal frame and lid by forming a compartment and a plurality of sidewalls in the seal frame and lid block, placing the seal frame and lid on the mandrel such that the mandrel fits within the compartment, and cofiring the seal frame and lid block.