Perpendicular Wire Bond Profiles for RF IC Cross Coupling
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Solution Overview
Problem
Traditional ball bonders struggle to produce desired wire bond profiles for RF integrated circuits, leading to skewed or bowed wire bonds, increased cross coupling, and the inability to achieve perpendicular crossing points, which are critical for optimal RF performance.
Innovation Solution
The technique involves applying a negative reverse motion and a positive reverse motion during the wire-bonding process to form bends in the wire, allowing for the creation of wire bond profiles that are shaped for optimal RF performance, with at least two profiles being substantially perpendicular at their crossing point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional ball bonding is used to form wire bond profiles, then the process is more economical and robust compared to wedge bonding, but the wire bond profiles become skewed or bowed away from the second bond site, failing to achieve the desired shape for optimal RF performance
Solution Approach 1:
The wire bonding process is segmented into multiple distinct phases: initial ball bonding, first reverse motion to create vertical section, second reverse motion to create bend, and final approach to second bond site. Each phase independently controls a specific segment of the wire profile, enabling precise shape control while maintaining ball bonding's economical and robust nature
Solution Approach 2:
The bonding tool is equipped with dynamic z-axis motion capability that allows it to move vertically during the wire bonding process. This dynamic motion enables the tool to create the desired wire bond profile shape by controlling wire feed timing and amount at different stages, transforming the static ball bonding process into a dynamic shape-control process
2Device complexity
If traditional ball bonders use a single reverse motion during wire bond profile formation, then the process is simpler, but the wire continues to be fed out during the approach to the second bond site, introducing variability in wire length and causing the profile to bow away from the second bond site
Solution Approach 1:
The reverse motion is segmented into two distinct reverse motions rather than a single continuous motion. The first reverse motion occurs immediately after ball bonding to create the vertical section, and the second reverse motion occurs later to create the bend. This segmentation allows precise control over wire feed timing and amount at each stage, eliminating the wire feeding variability that occurs with a single reverse motion approach
3Ease of manufacture
If wire bond profiles are allowed to skew or bow away from the second bond site, then the ball bonding process can be used, but this causes increased cross coupling with other wire bonds in the RF integrated circuit
Solution Approach 1:
The bonding tool employs dynamic z-axis motion to actively control the wire bond profile shape throughout the bonding process. By moving the tool vertically at precisely controlled times, the system creates a wire profile that remains substantially perpendicular at crossing points, minimizing cross coupling. This dynamic control enables ball bonding to achieve the same cross coupling performance as traditional wedge bonding while retaining ball bonding's economical and robust advantages
Data Source
AI summary
Techniques for ball bonding wires in an integrated circuit are provided which allow formation of desired wire bond profile shapes for optimal performance. A wire is ball bonded to a first bond site in the integrated circuit with a bonding tool and at least one bend is formed in the wire. The wire is terminated at a second bond site with the bonding tool, thereby creating a wire bond profile. The technique is repeated for a plurality of additional wire bonds of the integrated circuit, and at least two wire bond profiles in the integrated circuit are substantially perpendicular to one another at a crossing point of the profiles.