MEMS Package Structure for Thin Sealing Layers Under Thermal Stress
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Solution Overview
Problem
Micro electro-mechanical systems (MEMS) packages face structural weaknesses due to low modulus and high coefficient of thermal expansion in polymer materials used, leading to potential collapse during molding and thermal stress issues.
Innovation Solution
A MEMS package design incorporating a first substrate with a connection pad, a second substrate with an element unit, a connecting member, a sealing layer made of photo-definable polymer, an insulating layer with higher strength, and a redistribution layer that connects the connection pad to an external terminal, which is exposed externally, along with a method involving lamination and photo-lithography processes to enhance structural integrity and manufacturing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polymer sealing layer is used to enclose the second substrate, then the package can be easily processed and manufactured, but the package has structural weakness due to low modulus and high coefficient of thermal expansion
Solution Approach 1:
The patent uses a composite structure combining a polymer sealing layer with a glass substrate. The glass substrate provides high modulus and low CTE for structural strength, while the polymer layer provides ease of processing and sealing functionality. This composite approach resolves the contradiction between manufacturability and structural strength.
Solution Approach 2:
The patent applies different materials with different properties to different parts of the package: the glass substrate provides structural rigidity where needed, while the polymer sealing layer provides sealing and ease of processing where applicable. This local differentiation of material properties resolves the contradiction between strength and ease of manufacture.
2Volume of moving object
If the polymer sealing layer is made thinner to reduce package size, then the package becomes more compact, but the cavity may collapse during molding or structural weakness occurs due to thermal stress
Solution Approach 1:
The glass substrate acts as a rigid support structure that prevents cavity collapse during molding even when the polymer sealing layer is thin. The high modulus of glass compensates for the reduced thickness of the polymer layer, maintaining structural reliability while enabling compact packaging.
Solution Approach 2:
The patent changes the material parameters by introducing glass with high modulus and low CTE to support the thin polymer sealing layer. This parameter change in material properties allows the polymer layer to be made thinner without compromising structural reliability during molding or under thermal stress.
3Productivity
If the package structure is simplified to improve manufacturing yield, then production efficiency increases, but thermal stress issues occur due to coefficient of thermal expansion differences
Solution Approach 1:
The glass substrate with low CTE is combined with the polymer sealing layer to create a composite structure that is less sensitive to thermal expansion differences. This composite approach maintains manufacturing yield while reducing thermal stress issues by using materials with complementary thermal properties.
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 solution effectively addresses structural weaknesses and improves manufacturing yield by providing a robust MEMS package that withstands thermal stress and maintains structural integrity through the use of a photo-definable polymer sealing layer and insulating layer, reducing the risk of collapse and enhancing external connection capabilities.
Implementation Method 1
The sealing layer may include a photo-definable polymer material
Implementation Method 2
the insulating layer comprises a photo-definable material which has a higher strength than a strength of the sealing layer
Data Source
AI summary
A micro electro-mechanical systems (MEMS) package includes a first substrate on which at least one connection pad is disposed; a second substrate disposed adjacent to the first substrate; an element unit disposed on one surface of the second substrate; a connecting member connected to the connection pad and a metal pad included in the element unit; a sealing layer which encloses the second substrate; an insulating layer which covers the sealing layer; a redistribution layer connected to the connection pad; and an external connection terminal connected to the redistribution layer and exposed externally from the insulating layer. The element unit is spaced apart from the first substrate, the external connection terminal is exposed externally from the insulating layer disposed on a surface of the package that is opposite to a surface thereof on which the first substrate is disposed.