Ball Forming Device Current Control Circuit Stability
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Solution Overview
Problem
Conventional ball forming devices for wire bonders face instability in forming initial balls due to varying discharge voltage and current, require resistor replacement for different wire types, and struggle with maintaining discharge during wire diameter changes, leading to decentering and inefficiency.
Innovation Solution
A ball forming device with a first current control circuit to manage discharge current and a second current control circuit with a fixed resistor in parallel, allowing for adjustable discharge voltage and stable current flow, enabling consistent ball formation across various wire types and diameters without resistor replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single constant current switch is used to control discharge current, then the device structure is simple, but discharge voltage varies with air pressure causing unstable initial ball formation
Solution Approach 1:
The control circuit is segmented into two independent parts: a constant current control circuit (first control circuit) that controls discharge current, and a constant voltage control circuit (second control circuit) that controls discharge voltage. This segmentation allows each circuit to independently stabilize its respective parameter, resolving the instability caused by air pressure variations while maintaining manageable circuit complexity.
Solution Approach 2:
The patent introduces dynamic control capabilities by making the discharge voltage adjustable through the second control circuit. This dynamic adjustment ability allows the system to adapt to different wire types and diameters, maintaining stable initial ball formation across various operating conditions without requiring physical resistor replacement.
2Adaptability or versatility
If resistor replacement is performed for different wire types, then discharge parameters can be optimized, but device complexity and maintenance burden increase
Solution Approach 1:
The second control circuit provides universal voltage control capability that works with different wire types (gold, copper, aluminum) and diameters. Instead of requiring different resistors for different wire types, the system uses a single universal circuit that can be electronically adjusted to optimize discharge parameters for any wire type, eliminating the need for physical component replacement.
Solution Approach 2:
The patent changes the approach from physical parameter changes (resistor values) to electrical parameter changes (controllable voltage output). The second control circuit enables dynamic adjustment of discharge voltage parameters, allowing the system to adapt to different wire types by changing electrical parameters rather than physical components, thereby reducing maintenance burden and increasing versatility.
3Manufacturing precision
If discharge current is attenuated to prevent decentering, then initial ball positioning improves, but discharge voltage decreases causing discharge to end prematurely
Solution Approach 1:
The second control circuit acts as an intermediary that decouples the relationship between current attenuation and voltage decrease. When the first control circuit attenuates discharge current to prevent decentering, the second control circuit simultaneously adjusts discharge voltage to maintain the required level, thereby extending discharge duration without compromising positioning accuracy.
Solution Approach 2:
The second control circuit performs preliminary voltage adjustment before and during the discharge process. By proactively maintaining discharge voltage at the required level, the system ensures that even when current is attenuated for positioning precision, the discharge can continue for the full required duration without ending prematurely.
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
The device stabilizes initial ball formation by maintaining discharge voltage and current, preventing decentering, and allowing for versatile bonding without resistor changes, enhancing power and efficiency in wire bonding processes.
Implementation Method 1
discharge is firstly caused by applying high voltage between a leading end of a wire fed from a capillary and a discharge electrode, and then, the leading end of the wire is melted with discharge energy
Implementation Method 2
the leading end of the wire is melted with discharge energy, so that a ball is formed at the leading end of the wire
Data Source
AI summary
A ball forming device includes a first current control circuit to control discharge current arranged between a leading end of a wire and one electrode of a discharge continuing power source for causing discharge current to flow after dielectric breakdown, a second current control circuit to control shunting of discharge current arranged between a discharge electrode and the other electrode of the discharge continuing power source, and a fixed resistor connected to the second current control circuit in parallel as a shunt and controls current flowing through the second current control circuit, thereby a discharge voltage value is adequately changed.