Stacked IC Die Isolation Layer for Inductive Coupling
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Solution Overview
Problem
In integrated circuit packaging with stacked die, achieving effective communication through inductive coupling while maintaining sufficient galvanic isolation is challenging due to the risk of destructive arcing caused by close proximity, which requires a balance between proximity for communication and electrical isolation to prevent die destruction and meet safety standards.
Innovation Solution
A preformed isolation layer extending beyond the edges of the top die, combined with a conductive ring on the isolation layer with rounded corners, is used to provide galvanic isolation and reduce electric field concentration, allowing inductors on adjacent dies to communicate effectively while preventing die destruction from arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the die are placed in close proximity for effective inductive coupling communication, then the communication effectiveness is improved, but the risk of destructive arcing increases due to higher electrical fields between the die
Solution Approach 1:
An isolation layer is introduced as an intermediary component between the first and second IC dies. This isolation layer provides galvanic isolation while allowing the die to remain in close proximity for effective inductive coupling communication. The isolation layer prevents direct electrical contact and reduces the risk of arcing while maintaining the magnetic coupling needed for communication.
Solution Approach 2:
The patent segments the electrical isolation function from the communication function by using separate components: the isolation layer handles electrical isolation while the inductors handle magnetic coupling communication. This segmentation allows optimization of each function independently - the die can be close for communication while the isolation layer prevents arcing.
2Object-affected harmful factors
If a thick isolation layer is used to prevent arcing and ensure galvanic isolation, then the safety standards are met, but the proximity between die is reduced which diminishes communication effectiveness
Solution Approach 1:
By stacking die in the vertical dimension with the isolation layer in between, the patent achieves both sufficient isolation thickness for arcing prevention and close horizontal proximity for effective magnetic coupling communication. The vertical stacking allows independent optimization of isolation thickness without compromising communication distance.
Solution Approach 2:
The isolation function is segmented into a dedicated isolation layer with optimized thickness for arcing prevention, while the communication function is maintained through inductors on each die. This segmentation allows the isolation layer to be thick enough for safety without preventing magnetic coupling between the inductors.
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 ensures effective communication between stacked IC dies with controlled thickness of the isolation layer and adhesive layers, reducing the risk of dielectric breakdown and corona effects, thus maintaining high voltage isolation and safety standards.
Implementation Method 1
galvanic isolation should be sufficient to prevent destruction of the isolation between the die and to maintain sufficient high voltage isolation
Implementation Method 2
Communication between integrated circuit (IC) die can be achieved using inductive coupling in which two die can use transmitting and receiving inductors to communicate
Implementation Method 3
a conductive ring is formed on the isolation layer, surrounding the top die, which extends partially under the top die and extends from the edges of the top die onto the isolation layer. This ring has rounded corners
Data Source
AI summary
A packaged integrated circuit (IC) device includes a first IC die with a first inductor, a first layer of adhesive on a first major surface of the first IC die, an isolation layer over the first layer of adhesive, a second layer of adhesive on the isolation layer, a second IC die on the second layer of adhesive, and a second inductor in the second IC die aligned to communicate with the first inductor. The isolation layer extends a prespecified distance beyond a first edge of the second IC die.