Resin Sealed Module Dual-Layer Structure Warpage Control
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Solution Overview
Problem
Resin-sealed modules experience warpage and detachment issues due to thermal expansion differences between thermosetting resin layers and substrates during reflow, leading to potential short failures.
Innovation Solution
A dual-layer resin structure is implemented, with a thermoplastic resin layer containing inorganic fillers on the substrate and a thermosetting resin layer on top, where the thermoplastic resin softens to reduce warpage and relieve stress from solder expansion, while the thermosetting resin maintains shape and laser printability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermosetting resin layer is used to seal the substrate, then the sealing reliability is improved, but substrate warpage occurs during re-reflow due to thermal expansion coefficient difference
Solution Approach 1:
The sealing resin layer is divided into two distinct layers: a lower thermoplastic resin layer (first resin layer) and an upper thermosetting resin layer (second resin layer). The thermoplastic layer contacts the substrate and absorbs thermal expansion stress through softening, while the thermosetting layer provides stable sealing. This segmentation resolves the contradiction by allowing each layer to perform its specialized function.
Solution Approach 2:
The invention uses a composite structure combining thermoplastic and thermosetting resins with different properties. The thermoplastic resin (lower layer) has low thermal expansion coefficient and softens at re-reflow temperatures to reduce warpage, while the thermosetting resin (upper layer) provides durable sealing. This composite material approach allows simultaneous achievement of warpage reduction and sealing reliability.
2Strength
If a thermosetting resin layer is used for sealing, then the sealing strength is improved, but detachment occurs between the resin layer and electronic components during re-reflow
Solution Approach 1:
The sealing function is segmented between two layers: the thermoplastic layer (first resin layer) provides stress absorption and bonding flexibility during thermal cycles, while the thermosetting layer (second resin layer) provides strong sealing strength. This segmentation allows each layer to optimize for its specific function without compromising the other.
Solution Approach 2:
The invention changes the thermal parameter profile of the sealing layer by using a thermoplastic resin with a softening point below the re-reflow temperature. This parameter change allows the lower layer to soften and absorb stress during re-reflow, preventing detachment while maintaining overall sealing integrity through the upper thermosetting layer.
3Shape
If a thermoplastic resin layer is used to reduce warpage, then the substrate warpage is reduced, but the laser printability is impaired
Solution Approach 1:
The sealing structure is segmented into two layers with differentiated functions: the lower thermoplastic layer (first resin layer) reduces warpage through softening, while the upper thermosetting layer (second resin layer) provides laser printability. This segmentation resolves the contradiction by assigning opposite properties to different layers.
Solution Approach 2:
Different regions of the sealing structure are given different material qualities: the lower layer near the substrate has low softening point for warpage control, while the upper layer exposed to laser has high stability for printability. This local quality differentiation allows each region to optimize for its specific requirement.
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
The dual-layer resin structure effectively reduces substrate warpage and detachment risks during reflow, preventing short failures and maintaining laser printability.
Implementation Method 1
the resin layer that contacts the substrate is made of a thermoplastic resin. Therefore, when the substrate undergoes thermal expansion during the re-reflow for mounting this resin-sealed module onto another substrate or the like, the warpage of the substrate can be reduced by softening of the resin layer
Implementation Method 2
Because the resin layer made of a thermosetting resin is provided on top of the resin layer made of a thermoplastic resin, it is possible to reduce the softening and the flowing of the thermoplastic resin during the re-reflow, thereby keeping the shape of the resin layer
Data Source
AI summary
A resin-sealed module is provided which reduces the warpage of a substrate and the detachment between a sealing resin and the substrate which occur during re-reflow, has the excellent flatness of the top and bottom surfaces, and reduces the occurrence of the short failures. A resin layer made of a thermoplastic resin is arranged on top of a substrate, and a resin layer made of a thermosetting resin is arranged on top of this resin layer, thereby reducing the warpage of the substrate and the detachment between the sealing resin and the substrate which occur during re-reflow.