Semiconductor Wire Turned-Back Portion Design
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Solution Overview
Problem
The increasing number of bonding wires in semiconductor devices due to large-scale integration leads to a need for reducing the resources used, particularly the material per connection, while maintaining the mechanical strength and preventing defects such as wire deformation and protrusions that can cause short circuits.
Innovation Solution
A semiconductor device design featuring a turned-back portion of the wire with a thickness smaller than its diameter, formed by crushing the wire with a capillary, which reduces the material usage and prevents protrusions, allowing for a lower wire height and increased adhesion strength without obstructing device thinness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the wire is made thinner to reduce material usage, then the quantity of wire material is reduced, but the mechanical strength and adhesion strength decrease
Solution Approach 1:
The wire structure is designed with varying local properties: the main body maintains sufficient thickness for strength, while the turned-back portion is localized and reduced in thickness to minimize material usage. This local differentiation allows the wire to achieve both reduced material quantity and maintained mechanical strength.
Solution Approach 2:
The wire is segmented into distinct functional portions: a main body portion for electrical connection and a turned-back portion for mechanical anchoring. This segmentation allows optimization of each portion independently, with the turned-back portion using less material while the main body maintaining adequate thickness for strength.
2Length of stationary object
If the wire height is reduced to improve device thinness, then the device profile is slimmer, but the wire may not have sufficient adhesion strength
Solution Approach 1:
The turned-back portion is formed with a curved, arc-shaped configuration rather than a straight line. This curvature allows the wire to follow a longer path within a compact vertical space, increasing the effective adhesion length without increasing the overall wire height, thus maintaining both device thinness and adhesion strength.
Solution Approach 2:
Instead of increasing wire height vertically to improve adhesion, the solution transitions to the horizontal dimension by creating a turned-back portion that extends laterally. This dimensional shift allows adhesion improvement without compromising device thinness in the vertical direction.
3Quantity of substance
If a turned-back portion is formed by crushing the wire with a capillary, then material usage is reduced and protrusions are prevented, but the manufacturing process becomes more complex
Solution Approach 1:
The capillary serves dual functions: it delivers the wire to the bonding location and simultaneously forms the turned-back portion through its crushing action. This self-service approach integrates the forming operation into the existing wire delivery mechanism, adding minimal complexity while achieving material reduction and protrusion prevention.
Solution Approach 2:
The capillary acts as an intermediary tool that mediates between wire delivery and turned-back formation. By using the capillary's physical presence and crushing action, the process achieves precise control over the turned-back portion geometry without requiring separate complex forming equipment.
4Object-affected harmful factors
If the thickness of the turned-back portion is reduced to prevent protrusions, then short circuit risks are reduced, but the wire's mechanical anchoring strength may be compromised
Solution Approach 1:
The thickness of the turned-back portion is optimized to a specific parameter range that balances two competing requirements: thin enough to prevent protrusions and short circuits, but thick enough to provide sufficient mechanical anchoring. This parameter optimization allows the wire to meet both electrical safety and mechanical strength requirements simultaneously.
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 solution effectively reduces the quantity of wire material used while maintaining a low wire height, enhancing mechanical strength and preventing defects like deformation and short circuits, thus addressing the resource and structural challenges in semiconductor devices.
Implementation Method 1
a turned-back portion 41 is formed on an end of the wire 40 on the side opposite to the second electrode 20. A thickness 41t of the turned-back portion 41 is smaller than a diameter 40d of the wire 40
Data Source
AI summary
According to one embodiment, a semiconductor device includes a first semiconductor element, a first electrode, a ball part, a second electrode, and a wire. The first electrode is electrically connected to the first semiconductor element. The ball part is provided on the first electrode. The wire connects the ball part and the second electrode. A thickness of a turned-back portion at an end of the wire on a side opposite to the second electrode is smaller than a diameter of the wire.