Compliant Layer Clamping for Semiconductor Bonding
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Solution Overview
Problem
Conventional clamping methods for ultrasonic bonding of semiconductor devices on highly populated lead-frames face challenges such as poor clamping due to flexibility, leading to damage, resonance issues, and inconsistency, especially with small and densely packed devices.
Innovation Solution
A clamping system utilizing a compliant layer and a window clamp with a protective layer to secure semiconductor devices during bonding, distributing clamping force evenly and preventing damage, while reducing resonance and improving consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If flexible clamp fingers are used to constrain lead-frames during ultrasonic bonding, then the clamping force can be applied, but large tip deflection occurs causing damage to lead-frames and resonance problems
Solution Approach 1:
The patent replaces traditional flexible clamp fingers with a compliant layer (flexible film/shell) that distributes clamping force across the entire lead-frame surface. This compliant layer is supported by a rigid structure, providing flexibility without the resonance and deflection problems of thin flexible fingers. The distributed force application eliminates concentrated stress points that cause lead-frame damage.
Solution Approach 2:
The patent introduces a compliant layer as an intermediary between the rigid clamp and the lead-frame. This intermediate layer acts as a force-distributing medium that transforms the concentrated force from traditional clamp fingers into a distributed pressure field, eliminating the harmful resonance and deflection effects while maintaining effective clamping.
2Ease of operation
If small and light clamp fingers are used to secure specific points on the lead-frame, then the bonding process can be performed, but unwanted resonance problems occur due to many modes in the frequency spectrum close to the bonding frequency
Solution Approach 1:
The compliant layer functions as a flexible film that provides the necessary compliance for bonding operations while having a much larger effective mass and different vibrational characteristics compared to small clamp fingers. This eliminates the resonance problems caused by light, flexible clamp fingers operating near the bonding frequency.
Solution Approach 2:
The patent fundamentally changes the physical parameters of the clamping system by transitioning from discrete, light clamp fingers to a continuous, distributed compliant layer. This parameter change alters the frequency spectrum and vibrational modes, moving them away from the problematic bonding frequency range while maintaining operational capability.
3Ease of operation
If conventional clamp fingers are used, then specific points on the lead-frame can be constrained, but the placement is constrained to areas encapsulated in the final package or areas that are cut away
Solution Approach 1:
The compliant layer provides universal clamping capability across the entire lead-frame surface, not limited to specific enclosed areas. This multi-functional approach allows clamping at any location on the lead-frame, including areas that would traditionally be inaccessible to clamp fingers, thereby increasing placement flexibility and adaptability.
Solution Approach 2:
The flexible nature of the compliant layer allows it to conform to and clamp various geometries and locations on the lead-frame without requiring discrete clamp fingers to be positioned in enclosed spaces. This eliminates the geometric constraints that limited traditional clamp placement locations.
4Quantity of substance
If highly populated lead-frames with small and thin tie bars are used to transport semiconductor devices, then cost is reduced, but properly constraining the packages during ultrasonic bonding becomes very difficult
Solution Approach 1:
The compliant layer provides gentle, distributed clamping that is suitable for highly populated lead-frames with small, thin tie bars. Unlike rigid or concentrated clamp fingers that could damage these delicate structures, the flexible film distributes force evenly, making it easy to constrain packages during bonding while preserving the integrity of the thin tie bars.
Solution Approach 2:
The patent changes the clamping approach from concentrated, high-stress points to distributed, low-stress areas, matching the physical characteristics of highly populated lead-frames. This parameter change in force distribution enables effective constraining of delicate, densely packed devices without damage.
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 enables reliable and consistent ultrasonic bonding of densely populated lead-frames by evenly distributing clamping force, reducing resonance issues, and allowing for larger areas of the lead-frame to be clamped without damage, resulting in improved bonding quality and process stability.
Implementation Method 1
a compliant layer over the base, wherein the compliant layer secures the semiconductor device to a window clamp during a bonding process
Implementation Method 2
the large ultrasonic wire or ribbon bonding process
Data Source
AI summary
In one embodiment, a support structure comprises a base, a compliant layer, and a protective layer which is used to secure a semiconductor device, such as a lead-frame, to a window clamp during a bonding process. The compliant layer distributes even loading over the surface of the semiconductor device while clamped. In other embodiments, the compliant layer may be segmented into individual portions corresponding with openings in the window clamp. The window clamp may also have a compliant layer and a protective layer and may be used with or without a compliant layer on the support structure. Features on the protective layer may be included to support structures of the semiconductor device.