Dual-Head Capillary Wire Bonding for Fine-Pitch Vertical Interconnects
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Solution Overview
Problem
Current interconnect architectures, such as wire bonds and flip chip technology, fail to provide low-cost, fine-pitch face-to-face connections between substrates due to the requirement for large pad sizes and high costs associated with redistribution layers in flip chip interconnects.
Innovation Solution
The implementation of a dual head wire bonding tool that allows for face-to-face wire bond connections between substrates by articulating two wires to form an electrical connection, eliminating the need for redistribution layers and enabling alignment-independent connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonds are used to connect conductive pads on opposing substrates, then interconnects between substrates are provided, but large wire loops are required which are hard to control and may lead to shorting
Solution Approach 1:
The patent inverts the conventional wire bonding approach by bringing wires together from opposite directions to meet at a central bonding point, rather than forming large loops. This inversion eliminates the wire loop control issues while maintaining connection reliability between substrates
2Reliability
If flip chip technology is used to provide face-to-face connections, then conductive pads can face each other, but large pitches are required to accommodate solder balls and copper pillar heights are limited
Solution Approach 1:
The patent extracts the bonding process from the conventional flip chip approach by using wire bonding to create face-to-face connections without requiring solder balls or copper pillars. This eliminates the pitch length constraints inherent in flip chip technology while maintaining reliable face-to-face connections
3Reliability
If flip chip interconnect architecture is used, then face-to-face connections are achieved, but redistribution layers are required which increase cost
Solution Approach 1:
The patent removes the requirement for redistribution layers by directly bonding wires to conductive pads on opposing substrates. This extraction of the RDL requirement significantly reduces manufacturing cost while maintaining reliable face-to-face interconnects
4Reliability
If conventional wire bond configuration is used with pads facing the same direction, then connections are made between substrates, but large pad sizes are required
Solution Approach 1:
The patent inverts the pad orientation approach by having conductive pads on opposing substrates face each other (face-to-face) rather than facing the same direction. This inversion enables smaller pad sizes while maintaining reliable connections through the wire bonding process
Data Source
AI summary
Embodiments disclosed herein include wire bonds and tools for forming wire bonds. In an embodiment, a wire bond may comprise a first attachment ball, and a first wire having a first portion contacting the first attachment ball and a second portion. In an embodiment, the wire bond may further comprise a second attachment ball, and a second wire having a first portion contacting the second attachment ball and a second portion. In an embodiment, the second portion of the first wire is connected to the second portion of the second wire.