Stacked BGA Devices Using Milled PCB Interconnect
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing techniques for stacking multiple integrated circuit (IC) devices in Ball Grid Array (BGA) packaging face mechanical weakness, low signal integrity, and high manufacturing costs, making them unsuitable for high-density microprocessor systems requiring efficient and reliable packaging.
Innovation Solution
A milled-down printed circuit board (PCB) is used as an interconnecting element with top and bottom contact pads, internal traces, and an adhesive layer to securely stack BGA devices, providing mechanical stability, thermal efficiency, and reliable solder connections, while maintaining compactness and co-planarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing stacking techniques are used for BGA packaging, then device stacking is achieved, but mechanical weakness and low signal integrity occur
Solution Approach 1:
The patent merges the interconnecting element with the PCB by directly forming contact pads on the PCB surface, eliminating the need for separate interconnecting components. This integration strengthens the mechanical bond between stacked BGA devices and the board while maintaining signal integrity through direct electrical connections, resolving the contradiction between reliability and manufacturing complexity.
Solution Approach 2:
The patent applies preliminary action by pre-forming contact pads on the PCB surface before device attachment. The contact pads are created with raised structures and adhesive layers in advance, ensuring proper mechanical support and electrical connection are ready before the BGA devices are stacked and soldered, thereby improving reliability without complicating the overall manufacturing process.
2Area of stationary object
If multiple IC devices are stacked to save space, then space efficiency is improved, but mechanical weakness and assembly challenges arise
Solution Approach 1:
The patent applies local quality by creating raised contact pads with adhesive layers at specific locations on the PCB surface where devices will be attached. This localized enhancement of mechanical properties at the attachment points provides strong mechanical support for stacked devices while maintaining the overall compact design, resolving the contradiction between space efficiency and mechanical strength.
3Reliability
If advanced packaging techniques like BGA are used, then performance characteristics are maintained, but existing stacking techniques become inapplicable
Solution Approach 1:
The patent achieves universality by designing a PCB-based interconnecting system that works specifically with BGA packaging while maintaining the ability to stack multiple devices. The raised contact pads and adhesive layer configuration are optimized for BGA devices, providing both the signal integrity required for high-performance BGA applications and the mechanical support needed for reliable device stacking, thus adapting advanced packaging to multi-device configurations.
Data Source
AI summary
An embodiment of the present invention is a technique to stack multiple devices using an interconnecting element. A board has a periphery and top and bottom surfaces. The top surface has top contact pads to attach to a first device. The bottom surface is milled down to form a cavity confined by vertical walls around the periphery. The cavity fits a second device. Bottom contact pads are formed on bottom side of the vertical walls. The bottom contact pads are raised with respect to the bottom side of the vertical walls. Traces internal to the board connect the bottom contact pads to the top contact pads.