Multi-Axis Ultrasonic Wedge Bonding for Low-Resistance Ribbon Interconnects
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Solution Overview
Problem
Existing wedge wire bonding technologies face challenges in achieving high conductivity and reliable electrical interconnects in battery modules, particularly due to limitations in bond area and adherence of bond wire material to electrical contact surfaces.
Innovation Solution
The use of multi-axis ultrasonic wedge bonding techniques, which involve rotating a wedge bonder head while activating ultrasonic transducers, to form wedge wire bonds with increased bond area and improved adherence, resulting in reduced electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional wedge wire bonding is used, then the bonding process is simple, but the bond area is limited and adherence is poor
Solution Approach 1:
The patent transitions from conventional single-axis linear bonding to multi-axis bonding that incorporates rotational motion and angular positioning. The wedge bonder head can rotate around the ribbon wire and position the wedge at various angles relative to the contact surface, effectively adding dimensional freedom to the bonding process. This enables the formation of larger bond areas by accessing different portions of the contact surface and creating overlapping bond zones.
Solution Approach 2:
The bonding system incorporates dynamic positioning capabilities where the wedge bonder head can rotate and adjust its orientation during the bonding process. The wedge angle and position are dynamically adjustable to optimize adherence to the contact surface. This dynamic adaptability allows the system to maintain optimal bonding conditions across varying geometries and surface conditions, improving both bond area and adherence without requiring overly complex fixed mechanisms.
2Reliability
If conventional wedge wire bonding is used, then the equipment is simple, but electrical resistance is high
Solution Approach 1:
By introducing rotational and angular positioning dimensions to the bonding process, the system can create multiple overlapping bond zones around the ribbon wire-contact surface interface. This multi-dimensional bonding approach increases the total effective bond area, which directly reduces electrical resistance at the interface. The ability to position the wedge at various angles ensures more comprehensive contact and material intermixing, improving electrical conductivity.
Solution Approach 2:
The patent utilizes ultrasonic vibration during the wedge bonding process to enhance material adherence and reduce electrical resistance. The ultrasonic energy promotes intimate contact between the bond wire material and the contact surface, breaking down surface oxides and contaminants, and facilitating metallurgical bonding. This vibrational assistance improves bond quality and electrical conductivity without requiring proportionally complex equipment additions.
3Reliability
If conventional wedge wire bonding is used, then the bonding process is fast, but adherence of bond wire material is poor
Solution Approach 1:
The multi-axis bonding system incorporates rotational motion and angular positioning to enhance material adherence. By rotating the wedge bonder head and adjusting the wedge angle during bonding, the system creates more intimate contact between the bond wire material and the contact surface. This multi-dimensional approach increases the effective bonding pressure distribution and promotes better metallurgical adhesion, ensuring superior adherence of the bond wire material to the electrical contact surface.
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
This approach enhances the conductivity of electrical interconnects in battery modules by increasing the bond area and improving the adherence of the bond wire material, thereby reducing electrical resistance and improving the overall performance of the battery module.
Implementation Method 1
activating an ultrasonic transducer of the wedge bonder head with the wedge in contact with the ribbon wire
Implementation Method 2
rotating the wedge bonder head with the wedge in contact with the ribbon wire
Data Source
AI summary
In a general aspect, an electrical device assembly (e.g., a battery module) can include a first electrical contact surface, a second electrical contact surface, and a ribbon wire extending along a longitudinal axis. The ribbon wire can include a first portion, a second portion and a third portion. The first portion of the ribbon wire can be coupled with the first electrical contact surface via a first wedge bond. The second portion of the ribbon wire can be coupled with the second electrical contact surface via a second wedge bond. The third portion of the ribbon wire can extend between the first portion and the second portion. The first portion can have a first width transverse to the longitudinal axis of the ribbon wire, and the third portion can have a second width transverse to the longitudinal axis, the first width being greater than the second width.