MEMS Package Two-Peak Epoxy Structure for Glass Stress Reduction
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Solution Overview
Problem
MEMS device packages face reliability issues due to excessive stress from epoxy coatings, leading to delamination, cracking, and failure in mechanical testing, particularly when fragile materials like glass panels are involved.
Innovation Solution
A two-peak epoxy profile is constructed by applying multiple layers of glob top epoxy, with post-placement processes to distribute stress over a larger area, reducing the magnitude of stress on fragile components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single layer of epoxy coating is applied to encapsulate wire bonds, then the encapsulation is simple and quick, but the stress concentration causes delamination and cracking of fragile components like glass panels
Solution Approach 1:
The single epoxy layer is segmented into multiple sub-layers (first epoxy layer, second epoxy layer, third epoxy layer) with different thicknesses and stress distribution characteristics. This segmentation allows stress to be distributed across multiple interfaces rather than concentrated in one layer, preventing delamination and cracking while maintaining encapsulation functionality.
Solution Approach 2:
Different epoxy layers are applied with different local qualities - the first epoxy layer has greater thickness for stress distribution, while subsequent layers have reduced thickness. This local quality variation optimizes stress management at different depths, protecting fragile components without compromising overall package reliability.
2Object-affected harmful factors
If multiple layers of epoxy are applied to distribute stress, then the stress on fragile components is reduced, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The epoxy application process is segmented into multiple discrete steps, each applying a specific layer with controlled thickness. This segmentation enables precise control over stress distribution while maintaining manufacturing feasibility through standardized layering procedures.
Solution Approach 2:
The first epoxy layer is applied preliminarily to establish the stress-distributing foundation before subsequent layers are added. This preliminary action creates a stress-management structure that protects fragile components from the outset, making the overall manufacturing process more reliable despite increased complexity.
3Reliability
If the epoxy layer thickness is increased to cover wire bonds, then the encapsulation is more complete, but the stress concentration increases causing component failure
Solution Approach 1:
The total epoxy thickness required for complete wire bond encapsulation is segmented across multiple layers. Each layer contributes to the overall coverage while distributing the stress burden, achieving both complete encapsulation and stress reduction through the multi-layer architecture.
Solution Approach 2:
The epoxy structure exhibits local quality variation where the first layer provides greater thickness for stress distribution, while subsequent layers provide thinner coverage. This local quality optimization ensures complete wire bond encapsulation while minimizing stress concentration on fragile components at critical interfaces.
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 two-peak epoxy profile effectively reduces stress on MEMS device packages, enhancing reliability by preventing delamination and cracking during mechanical testing.
Implementation Method 1
applying a first post gel heat treatment to the first epoxy layers; applying a second post gel heat treatment to the first epoxy layers and the second epoxy layers
Data Source
AI summary
An example method of producing a microelectromechanical system (MEMS) package, the method comprising: applying first epoxy layers to a first substrate, at least one of the first epoxy layers coupled to a second substrate; applying a first post gel heat treatment to the first epoxy layers; after applying the first post gel heat treatment to the first epoxy layers, applying second epoxy layers to the second substrate and to the first epoxy layers; and applying a second post gel heat treatment to the first epoxy layers and the second epoxy layers.