Wire Bonding Control Using Bump Height and Position Sensing
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Solution Overview
Problem
Existing methods for adjusting terminal heights on circuit boards for semiconductor chip mounting are inefficient and prone to bonding defects due to inaccurate bump height calculations and adhesive application.
Innovation Solution
A wire bonding apparatus and method that utilizes a bonding tool, ultrasonic horn, load sensor, position detecting part, and controller to accurately calculate bump heights and adjust adhesive application based on relative positional relationships of bumps on the chip surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to measure circuit board surface and adjust terminal heights, then the process can be completed with simple equipment, but the measurement precision and manufacturing precision are insufficient leading to bonding defects
Solution Approach 1:
The bonding apparatus is divided into multiple independent detection components: a first detection unit for measuring circuit board surface height, a second detection unit for measuring bump height, and a third detection unit for measuring terminal contact height. Each unit independently measures specific parameters, and the controller integrates these measurements to calculate precise adjustment amounts, thereby achieving high measurement precision without requiring a single complex measurement system
Solution Approach 2:
The controller acts as an intermediary that receives measurement data from multiple detection units, calculates the required adjustment amount based on the formula involving circuit board surface height, bump height, and terminal contact height, and then controls the height adjustment mechanism. This intermediary processing enables precise coordination between multiple simple detection components to achieve accurate terminal height adjustment
2Reliability
If terminal heights are adjusted using conventional methods, then the device complexity remains low, but the reliability of wire bonding decreases due to inaccurate bump height calculations
Solution Approach 1:
The apparatus implements a closed-loop feedback system where the first detection unit continuously monitors circuit board surface height, the second detection unit measures actual bump heights after formation, and the third detection unit verifies terminal contact heights. The controller compares these measurements with target values and automatically adjusts terminal heights accordingly, ensuring reliable wire bonding by continuously feedback-controlled precision adjustment
Solution Approach 2:
The system performs preliminary measurements of circuit board surface height and bump height before terminal height adjustment. The controller calculates the required adjustment amount in advance based on these preliminary measurements, allowing the height adjustment mechanism to be positioned precisely before actual bonding occurs, thereby ensuring bonding reliability without requiring complex real-time adjustment mechanisms
3Manufacturing precision
If multiple detection units and control mechanisms are added to improve measurement precision, then bonding accuracy improves, but the ease of operation and device complexity increase
Solution Approach 1:
The bonding apparatus implements self-service automation where the multiple detection units automatically measure circuit board surface height, bump height, and terminal contact height without manual intervention. The controller automatically processes these measurements, calculates the optimal adjustment amount, and controls the height adjustment mechanism autonomously. This self-service capability maintains ease of operation by eliminating the need for operators to manually coordinate multiple measurements while achieving high manufacturing precision
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
Enhances the accuracy of wire bonding by reducing defects and ensuring precise bonding conditions, thereby improving the reliability and efficiency of the bonding process.
Implementation Method 1
bond a wire to a bonding point by generating an ultrasonic vibration in a state in which the wire is pressed onto the bonding point
Implementation Method 2
bond the wire to a bonding point by generating an ultrasonic vibration
Data Source
AI summary
According to one embodiment, a controller of a wire bonding apparatus is configured to calculate a height of a bump based on a diameter of a ball-shaped portion detected by a diameter detecting part, a first position of a bonding tool detected by a position detecting part when a load sensor detects a load at a bonding point, and a second position of the bonding tool when the bonding tool is lowered most at the bonding point, and to bond a wire based on the calculated height of the bump. The controller is further configured to acquire a plurality of the first positions of a plurality of the bumps formed on a chip, and to calculate a relative positional relationship of the plurality of first positions.