Flip-Chip Bonding Head Gap Control During Bump Melting
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Solution Overview
Problem
Conventional flip chip bonding methods risk short circuit failures due to excessive crushing of molten bumps and inaccurate gap management between the chip and substrate, caused by distortion and thermal expansion of the mounting tool.
Innovation Solution
A manufacturing apparatus and method that includes a lifting and lowering mechanism to eliminate distortion of the bonding head before bump melting, and performs position control to maintain a specified gap, using detection and control processes to manage thermal expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the chip is continuously pressurized with constant load until the bump is completely melted, then the bonding process can be completed, but the molten bump may be greatly crushed causing short circuit failure
Solution Approach 1:
The distortion elimination processing is performed preliminarily before the bump melting occurs. The lifting and lowering mechanism is driven in the lifting direction to eliminate mounting tool distortion while the bump is still solid, preventing the distortion from affecting the molten bump later. This preliminary action resolves the contradiction by preparing the system in advance to avoid the harmful effect.
Solution Approach 2:
The bonding process is divided into distinct periodic stages: first processing (pressurization before heating), distortion elimination processing (lifting during heating), and second processing (position control after distortion elimination). By periodically switching between these stages, the system maintains constant load during critical phases while eliminating distortion at appropriate intervals, preventing bump crushing.
2Force
If the mounting tool is distorted during pressurization, then the constant load can be maintained, but the distortion is instantly eliminated when the bump melts causing the tip to move and crush the molten bump
Solution Approach 1:
The distortion is eliminated preliminarily during the heating phase before the bump melts. The lifting and lowering mechanism is driven in the lifting direction to counteract the distortion that would otherwise occur during pressurization. This preliminary elimination of distortion prevents the sudden position change that would crush the molten bump, while still allowing constant load to be applied.
Solution Approach 2:
The system dynamically adjusts the lifting and lowering mechanism based on the heating stage. During first processing, constant load is maintained. During distortion elimination processing, the mechanism lifts to compensate for thermal distortion. During second processing, position control is performed to cancel thermal expansion and contraction. This dynamic adaptation resolves the contradiction between maintaining constant load and controlling gap precision.
3Manufacturing precision
If position control is performed to cancel thermal expansion and contraction, then the gap amount can be maintained at target value, but the system complexity increases
Solution Approach 1:
The thermal expansion and contraction compensation is performed as a preliminary consideration in the position control strategy. The controller is programmed to anticipate thermal effects and adjust positions accordingly during the second processing stage. This preliminary planning approach achieves precise gap control without requiring complex real-time sensing and adjustment mechanisms.
Solution Approach 2:
The position control system uses feedback from the lifting and lowering mechanism to maintain the gap amount at the target value. The controller monitors the position and adjusts the mechanism to compensate for thermal expansion and contraction. This feedback-based approach achieves high precision while keeping the system architecture relatively simple by using the existing mechanism for compensation.
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
Prevents excessive crushing of molten bumps, ensuring accurate gap management and reducing the risk of short circuit failures in semiconductor devices.
Implementation Method 1
the chip is heated to melt the bump
Implementation Method 2
the bump is melted
Implementation Method 3
position control is performed on the lifting and lowering mechanism so as to cancel thermal expansion and contraction of the bonding head
Data Source
AI summary
A manufacturing apparatus of a semiconductor device includes: a stage; a bonding head, including a mounting tool, a tool heater, and a lifting and lowering mechanism; and a controller performing bonding processing. The controller performs, in the bonding processing: first processing in which, after a chip is brought into contact with a substrate, as heating of the chip is started, the chip is pressurized against the substrate; distortion elimination processing in which, after the first processing and before melting of a bump, the lifting and lowering mechanism is driven in a lifting direction, thereby eliminating distortion of the bonding head; and second processing in which, after the distortion elimination processing, position control is performed on the lifting and lowering mechanism so as to cancel thermal expansion and contraction of the bonding head, thereby maintaining a gap amount at a specified target value.