Flip-Chip Pressing Jig Vacuum Suction Deformation Control
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Solution Overview
Problem
Conventional flip-chip semiconductor packaging processes face issues with chip deformation due to internal stress and thermal expansion coefficient differences, leading to ineffective solder bump connection and non-wetting problems during the reflow process.
Innovation Solution
The bonding equipment employs a pressing jig with a channel for vacuum suction to grip the chip module, a carrier jig for circuit board fixation, and a heating device using a laser beam to reflow solder bumps, while multi-functional sensors monitor the reflow condition in real-time to correct any deformation and ensure proper bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the chip thickness is thinned to hundreds of microns or less to achieve small form factor, then the chip can be made smaller and more integrated, but the chip is easily bent or warped due to internal stress, resulting in deformation of the chip module
Solution Approach 1:
The pressing jig applies downward pressure on the chip module before the reflow process to counteract the upward warping force that will occur during heating. This preliminary anti-action prevents the chip from deforming during the subsequent thermal processing, allowing thin chips to be used without suffering from warpage issues.
Solution Approach 2:
The chip module is positioned and secured on the pressing jig before heating begins. The pressing jig is configured to apply controlled pressure to the chip module in advance, establishing a stable configuration that prevents deformation during the reflow process.
2Stability of the object's composition
If the pressing jig presses down the chip module during subsequent flip-chip process, then the chip module is constrained, but the solder bumps cannot be effectively connected to the corresponding contacts due to chip deformation
Solution Approach 1:
The pressing jig applies downward pressure to counteract the warping tendency of the chip during heating. By applying this counteracting force before and during the reflow process, the chip remains flat and stable, ensuring that the solder bumps maintain proper alignment with the contacts for effective connection.
3Temperature
If the laser beam is used to heat the solder bumps for reflow, then the solder bumps are melted and reflowed, but the temperature of the chip module and circuit board rises together, causing bending or warping due to thermal expansion coefficient differences
Solution Approach 1:
The pressing jig applies downward pressure on the chip module to counteract the warping force generated by thermal expansion differences between the chip, circuit board, and encapsulation layer during laser heating. This preliminary anti-action maintains chip flatness despite the temperature rise.
Solution Approach 2:
The chip module is secured on the pressing jig before laser heating begins, establishing a constrained configuration that prevents thermal warping. The pressing jig is positioned and pressure is applied in advance, so when the laser beam heats the solder bumps, the chip remains stable and flat.
4Temperature
If the chip module is heated during reflow process, then the solder bumps are reflowed for bonding, but the solder bumps are prone to non-wetting problem due to chip warping
Solution Approach 1:
The pressing jig applies downward pressure to counteract the warping tendency of the chip during reflow heating. By maintaining the chip in a flat, constrained position, the solder bumps remain properly aligned with the contacts, ensuring effective wetting and reliable bonding without non-wetting defects.
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 suppresses chip module deformation, ensures reliable solder bump connection, and prevents non-wetting issues by maintaining precise control over the reflow process, improving the yield and quality of electronic devices.
Implementation Method 1
a pressing jig having a channel and configured to grip a chip module via vacuum suction through the channel
Implementation Method 2
a laser beam L is used to irradiate the semiconductor chips 11 along a direction from the pressing jig 9 toward the circuit board 13 (e.g., the downward heating direction H as shown in FIG. 1C) to transfer energy to the solder bumps 14 to melt the solder bumps 14
Data Source
AI summary
A flip-chip process is to provide a pressing jig with a channel, so that the pressing jig grips a chip module by vacuum suction through the channel, and the chip module can be bonded onto a circuit board via a plurality of solder bumps through the pressing jig, and then a heating device is provided to heat the plurality of solder bumps and reflow the plurality of solder bumps. Therefore, the chip module can be vacuum-gripped by the pressing jig to suppress deformation of the chip module, so that the solder bumps can effectively connect to corresponding contacts of the circuit board.