3D Electronic Module With Flexible Circuit Interconnects
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Solution Overview
Problem
High-frequency components, such as memories and processors, pose efficiency challenges when tested and stacked in 3D electronic modules, as some chips may not operate at maximum frequency, leading to suboptimal performance in modules comprising multiple chips.
Innovation Solution
A 3D electronic module design featuring encapsulated chips with output balls, flexible circuits, and a rigid printed circuit for mechanical and electrical linkage, along with optional passive and active components, allowing for efficient high-frequency operation and thermal management through radiators and epoxy resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If bare chips are stacked in a 3D electronic module, then the module can achieve high density integration, but some chips cannot operate at maximum frequency above 1 GHz
Solution Approach 1:
The system segments the chip testing and interconnection function into two parts: bare chips provide computing function while separate ball grid array packages provide the interconnection and testing interface. This allows the chips to operate at high frequency without being burdened by testing infrastructure.
Solution Approach 2:
The ball grid array packages serve as intermediary components between the bare chips and the external test sockets. These packages with larger pitch solder balls enable proper socket testing while the bare chips maintain their high-frequency operation capabilities.
2Reliability
If encapsulated chips with larger pitch solder balls are used, then test sockets can be used for complete testing, but the stacking technology must be adapted to these boxes
Solution Approach 1:
Flexible circuits are used to connect the ball grid array packages, allowing the system to adapt to the package geometry while maintaining electrical connections. The flexible nature accommodates the larger pitch packages without requiring complex rigid interconnection structures.
Solution Approach 2:
The system transitions from planar chip stacking to three-dimensional module stacking, where ball grid array packages are arranged in a 3D configuration connected by flexible circuits. This dimensional change allows proper testing access while achieving high integration density.
3Ease of operation
If flexible circuits are folded to connect to side faces of casings, then mechanical and electrical linkage is achieved, but the folded parts require protection and precise alignment
Solution Approach 1:
The flexible circuits are pre-formed with folded configurations before assembly, and the ball grid array packages are pre-positioned on the rigid circuit board. This preliminary preparation ensures proper alignment during final assembly, reducing manufacturing precision requirements during the stacking process.
Solution Approach 2:
The patent employs a bead of epoxy resin at the fold to protect and secure the flexible circuit. This simple, inexpensive material provides the necessary mechanical protection and alignment fixation without requiring complex precision mechanisms.
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
Enables a 3D electronic module that can operate at high frequencies with all components functioning at maximum capacity, with improved thermal management and reduced limitations on the number of stacked modules, while maintaining mechanical and electrical connectivity.
Implementation Method 1
a bead of epoxy resin placed at the edge of the module between the two flexible circuits along the bend of the flexible circuits
Implementation Method 2
at its end a folded part and glued to a side face of the associated casing
Data Source
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AI summary
The invention relates to a 3D electronic module (100) which comprises: - 2 electrically tested electronic boxes (10) each comprising at least one encapsulated chip (11) and output balls (13) on one face of the box called the main face (15), - 2 flexible circuits (20) mechanically linked together and respectively associated with a box (10), and arranged between the 2 boxes, each flexible circuit (20) comprising: o on one face (21) the first electrical interconnection pads (22) facing the output balls (13) of the associated box, o at its end a folded part (16) on a lateral face (16) of the associated box, o second electrical interconnection pads (24) on the opposite face of this folded part (26).