Multi-chip Package Face-down Stacking
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Solution Overview
Problem
Conventional multi-chip packages face challenges with increased thickness, impedance mismatch, higher manufacturing costs, and short circuits due to the use of metal wires for electrical connections, as well as limitations in selecting semiconductor chip sizes for stacking.
Innovation Solution
A multi-chip package design that uses face-down stacked semiconductor chips with metal patterns and connectors, eliminating the need for long metal wires by forming electrical connections between metal patterns and substrate electrode terminals, thereby reducing package thickness and manufacturing complexity while allowing for flexible chip size selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal wires are used to electrically connect bonding pads to electrode terminals, then electrical connections can be established, but the package thickness increases and short circuits may occur
Solution Approach 1:
The patent extracts and eliminates the metal wires from the electrical connection structure. Instead of using metal wires to connect bonding pads to electrode terminals, the invention directly connects bonding pads to bump electrodes, and bump electrodes to through-electrode holes in the substrate, thereby removing the source of thickness increase and short circuit risks while maintaining electrical connectivity
Solution Approach 2:
The patent introduces bump electrodes as intermediary connection elements between bonding pads and through-electrode holes. These bump electrodes serve as mediators that enable direct electrical connection without requiring long metal wire loops, thus reducing package thickness while ensuring reliable electrical connections
2Reliability
If metal wires are used for electrical connections, then connections can be formed, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent removes metal wires from the manufacturing process entirely. The electrical connections are achieved through bump electrodes and direct bonding pad connections, eliminating wire bonding steps, wire protection coating processes, and associated quality control steps, thereby simplifying manufacturing and reducing costs
Solution Approach 2:
The bonding pads directly serve as connection points for bump electrodes without requiring additional metal wire intermediaries. The substrate's through-electrode holes automatically provide the connection path to electrode terminals, making the structure self-connecting and eliminating complex wire bonding manufacturing steps
3Reliability
If center pad type semiconductor chips are used with metal wires, then electrical connections can be made, but protective coatings are required increasing cost and processes
Solution Approach 1:
The patent extracts and eliminates the need for protective coatings by removing long metal wire loops. Since bump electrodes create short, direct connections and metal wires are completely removed, the vulnerability requiring protective coatings disappears, simplifying the device structure and manufacturing
Solution Approach 2:
The patent replaces expensive and complex protective coating processes with a simpler structure that inherently requires no such protection. The direct bump electrode connections are so short and robust that they eliminate the need for additional protective layers, reducing both cost and process complexity
4Reliability
If metal wires are used for electrical connections, then connections can be established, but impedance matching becomes difficult reducing operating speed
Solution Approach 1:
The patent removes metal wires that caused impedance matching difficulties. The direct connection path from bonding pad through bump electrode to through-electrode hole creates a controlled, short transmission path that is easier to impedance match, thereby improving signal integrity and operating speed
Solution Approach 2:
The patent changes the connection geometry parameters by eliminating long wire loops and using short bump electrode connections. This parameter change reduces signal path length and improves impedance control, enabling faster operating speeds while maintaining reliable electrical connections
5Reliability
If semiconductor chips are stacked with metal wires, then electrical connections can be made, but wire contact during bonding and molding causes short circuits
Solution Approach 1:
The patent completely extracts and removes metal wires from the stacked chip structure. Without metal wires extending across the package, there is no possibility of wire-to-wire contact during bonding or molding processes, eliminating short circuit defects while maintaining necessary electrical connections through bump electrodes
Solution Approach 2:
The patent converts the potential harm of wire contact into a benefit by removing wires entirely and using bump electrodes that are positioned and protected by the chip and substrate structures themselves. The molding compound that previously threatened to cause short circuits now serves to protect and stabilize the bump electrode connections
Data Source
AI summary
A multi-chip package is presented which includes a substrate, a lower semiconductor, an upper semiconductor chip, metal wires, an encapsulant, and mounting units. The substrate has electrode terminals on an upper surface and ball lands on a lower surface. The lower semiconductor chip is placed face-down on the substrate. The lower semiconductor chip has first bonding pads, first connectors and metal patterns. The upper semiconductor chip is placed face-down type on the back surface of the lower semiconductor chip. The upper semiconductor has second bonding pads and second connectors. The metal wires electrically the lower semiconductor chip to the substrate. The encapsulant seals the substrate, the lower semiconductor chip, the upper semiconductor chip and the metal wires. The mounting units are on the lower surface of the substrate.