Flexible Semiconductor Package Structure with Matched Thermal Expansion
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Solution Overview
Problem
Conventional semiconductor package structures are stiff, making them unsuitable for flexible devices or those with curved surfaces, as they can lead to stress concentration and delamination issues when bent.
Innovation Solution
A flexible semiconductor package structure is developed without a solid substrate or leadframe, featuring a conductive structure with insulation and circuit layers, an encapsulant with reduced reinforcement, and a metal layer with a coefficient of thermal expansion and bending modulus closely matched to the circuit layer, to distribute stress and prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a solid molding compound is used after curing, then the semiconductor package structure gains structural stability and strength, but it becomes stiff and unsuitable for flexible devices or curved surfaces
Solution Approach 1:
The patent changes the physical state parameter of the molding compound from solid (cured) to liquid or gel state, enabling the package to be flexible while maintaining structural integrity. This parameter change allows the material to conform to curved surfaces and flexible substrates without delamination or stress concentration.
Solution Approach 2:
The patent uses a composite structure combining the semiconductor element, flexible substrate, and liquid/gel molding compound. This composite approach allows each layer to contribute its specific properties - the substrate provides flexibility while the molding compound provides protection and stress distribution without rigidification.
2Ease of manufacture
If a stiff package structure is used, then manufacturing and assembly are simplified, but stress concentration and delamination occur when bent or curved
Solution Approach 1:
By changing the molding compound to a liquid or gel state, the patent eliminates the need for rigid structural support while maintaining ease of manufacturing. The liquid/gel material can be easily dispensed and cured in place, simplifying assembly while preventing delamination through its conformal nature and stress-distributing properties.
3Stability of the object's composition
If the coefficient of thermal expansion and bending modulus of the upper element are closely matched to the circuit layer, then warpage and delamination are reduced, but material selection becomes more constrained
Solution Approach 1:
The patent uses the liquid or gel state of the molding compound to decouple the thermal expansion and bending modulus matching requirements. The liquid/gel material can accommodate a wider range of thermal and mechanical property variations without causing warpage or delamination, thus expanding material selection flexibility while maintaining composition stability.
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 provides a flexible semiconductor package that reduces stress concentration and delamination, maintaining structural integrity and functionality on curved surfaces while minimizing warpage and cracking.
Implementation Method 1
a coefficient of thermal expansion of the upper element is in a range of variation less than or equal to about ±20% of a coefficient of thermal expansion of the circuit layer
Implementation Method 2
a bending modulus of the upper element is in a range of variation less than or equal to about ±35% of a bending modulus of the circuit layer
Implementation Method 3
the metal layer is electrically insulated from the conductive structure
Data Source
AI summary
A method for manufacturing a semiconductor package structure includes: (a) disposing at least one semiconductor element on a conductive structure, wherein the conductive structure includes at least one insulation layer and at least one circuit layer; (b) disposing an encapsulant on the conductive structure to cover the semiconductor element; (c) attaching a supporting structure on the conductive structure to surround the semiconductor element; and (d) disposing an upper element on the encapsulant, wherein a coefficient of thermal expansion of the upper element is in a range of variation less than or equal to about ±20% of a coefficient of thermal expansion of the circuit layer, and a bending modulus of the upper element is in a range of variation less than or equal to about ±35% of a bending modulus of the circuit layer.