SAW Filter Module Packaging With Preformed Chip Cavities
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Solution Overview
Problem
Conventional surface acoustic wave filter module packaging methods using wafer level packaging and injection molding are costly and prone to reliability issues due to chip deformation and cracking, with plastic sealing leading to structural instability.
Innovation Solution
A packaging structure and method involving a substrate with surface acoustic wave filter and non-filter chips, fixed by convex structures, covered by a dry film layer and sealed with a plastic layer, forming cavities between chips and substrate, using vacuum airbag lamination and epoxy resin materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wafer level packaging with injection molding is used, then packaging cost is reduced, but chip deformation and cracking occur leading to reliability issues
Solution Approach 1:
The packaging process is segmented into distinct stages: wafer-level cavity formation, chip mounting, and individual module sealing. This allows the cavity structure to be formed early when chips are still on the wafer, then chips are mounted onto substrates and sealed individually, avoiding the need for high-pressure injection molding that causes chip deformation and cracking.
Solution Approach 2:
The cavity structure is formed preliminarily at the wafer level before chip mounting. By pre-forming the cavities in the substrate while chips are still attached to the wafer, the subsequent chip mounting and sealing processes can proceed without requiring excessive injection pressure, thereby preventing chip deformation and cracking.
2Ease of manufacture
If compression molding is used for plastic sealing, then packaging is completed, but cavities form on the plastic sealing layer surface causing structural instability
Solution Approach 1:
The cavity structures are formed preliminarily in the substrate before the plastic sealing layer is applied. Since the cavities already exist in the substrate, the plastic sealing layer can be molded over them without requiring compression molding that would create surface cavities, thereby maintaining the structural stability of the sealing layer.
3Manufacturing precision
If high injection pressure is applied during packaging, then cavity formation is ensured, but chip convex structure deformation and cracking occur
Solution Approach 1:
The cavity formation process is segmented from the chip sealing process. Cavities are formed in the substrate at the wafer level using low pressure, then chips are mounted and sealed individually. This segmentation eliminates the need for high-pressure injection molding, preventing chip convex structure deformation and cracking while ensuring proper cavity formation.
Solution Approach 2:
Cavity formation is performed as a preliminary action before chip mounting and sealing. By pre-forming cavities in the substrate, the subsequent sealing process can be performed at low pressure, avoiding the high injection pressure that would deform or crack chip convex structures.
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
Ensures reliable formation of cavities between chips and substrate, reducing costs and chip damage, enhancing structural integrity and reliability.
Implementation Method 1
The dry film layer attaches and covers the surface acoustic wave filter chip and the non-filter chip by vacuum airbag lamination
Data Source
AI summary
The present invention provides a surface acoustic wave filter module packaging structure and packaging method thereof. The packaging structure includes a substrate, a surface acoustic wave filter chip, a non-filter chip, a dry film layer, and a plastic sealing layer. The surface acoustic wave filter chip is fixed to the substrate by first convex structures, a first cavity is formed between the surface acoustic wave filter chip and the substrate. The non-filter chip is fixed to the substrate by second convex structures, a second cavity is formed between the non-filter chip and the substrate. The packaging structure and method thereof of the present invention can ensure that a cavity can be formed between the bottom of all chips and the substrate, avoiding the use of injection molding processes based on wafer level packaging filters, reducing costs and damage to chips during reliability testing.