Ball Mounting Method Using Dual Viscosity Fluids
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Solution Overview
Problem
Existing methods for mounting conductive balls on a circuit board using viscous fluid face challenges with insufficient holding force, leading to high defect rates, particularly when multiple transfers of viscous fluid reduce the amount on the board, making it difficult to securely attach thousands to hundreds of thousands of balls.
Innovation Solution
A ball mounting method employing two trays with different viscosity levels of viscous fluid, where transfer pins are immersed in a high-viscosity fluid and conductive balls are immersed in a lower-viscosity fluid, ensuring a strong holding force for secure attachment without leaving balls in the trays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a worker manually picks up and mounts balls onto the substrate, then the ball mounting process can be completed, but the productivity is low and labor costs are high
Solution Approach 1:
The mounting head is divided into multiple independent ball mounting units (e.g., 5 units arranged in a matrix), each capable of mounting balls independently. This segmentation allows parallel processing of multiple balls simultaneously, dramatically increasing productivity while keeping each individual unit relatively simple in structure.
Solution Approach 2:
The ball mounting units are designed with universal functionality to handle different ball sizes and types. The same mounting unit can be configured to mount various semiconductor balls (e.g., different diameters) by adjusting parameters, eliminating the need for completely different mounting mechanisms for each ball type.
2Productivity
If automated ball mounting equipment is used, then productivity increases, but the cost of the mounting equipment becomes extremely high
Solution Approach 1:
By segmenting the mounting head into multiple independent units that can be manufactured using standard techniques, the overall system cost is reduced. Each unit can be produced separately and assembled, avoiding the need for expensive custom-built automated equipment while achieving high throughput through parallel operation.
Solution Approach 2:
Multiple identical ball mounting units are created as copies of a single standardized design. This allows for economies of scale in manufacturing and maintenance, reducing the overall cost compared to developing and deploying expensive proprietary automated mounting systems.
3Manufacturing precision
If conventional mounting methods are used, then existing equipment can be utilized, but the mounting precision and reliability are insufficient for advanced semiconductor devices
Solution Approach 1:
The ball mounting units incorporate localized precision mechanisms specifically at the ball contact and placement points, while other parts of the system maintain simpler structures. This includes precision positioning mechanisms and controlled release structures only where needed for ball mounting, achieving high precision without making the entire system complex.
Solution Approach 2:
The invention replaces complex mechanical positioning and release mechanisms with a more straightforward approach using controlled material properties. The ball mounting units utilize the elastic properties of the ball material and controlled release structures to achieve precise placement, substituting complex mechanical systems with simpler physics-based mechanisms.
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 effectively increases the holding force for conductive balls on the circuit board, reducing defects by maintaining a sufficient amount of viscous fluid and preventing balls from being left in the trays, allowing for accurate and reliable mounting.
Implementation Method 1
Viscous fluid is used to mount conductive balls on a circuit board, and the conductive balls are fixed onto the circuit board by the viscous fluid
Implementation Method 2
in the ball immersion step, the conductive balls, which are held by the ball holder, are immersed in the viscous fluid of the second tray
Data Source
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AI summary
In a working machine for a circuit board including a working device that selectively performs work for mounting conductive balls on the circuit board by a ball holder 82 and performs work for transferring viscous fluid onto the circuit board by transfer pins, and a tray in which the viscous fluid is stored, when the conductive balls are to be mounted on the circuit board, the viscous fluid is transferred onto the circuit board by the transfer pins and the conductive balls having been immersed in the viscous fluid are mounted on the transferred viscous fluid. Accordingly, the conductive balls can be fixed onto the circuit board by the viscous fluid, which is transferred onto the circuit board by the transfer pins, and the viscous fluid that adheres to the conductive balls due to the immersion of the conductive balls in the viscous fluid. Therefore, the conductive balls can be appropriately mounted on the circuit board by a large amount of viscous fluid.