Solder Bump Bonding Structure With TCB Height Control
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Solution Overview
Problem
Conventional reflow methods for solder bumps in semiconductor chip bonding, such as convection-type and thermal compressive reflow, face issues like high thermal budgets causing warpage and delamination in dies, particularly in low-k dielectric layers.
Innovation Solution
The use of thermal compression bonding (TCB) with a TCB bonding head and vacuum chuck table maintains precise height control during solder bump reflow, forming column or hourglass-shaped joints to improve coplanarity and prevent warpage, using vacuum forces to hold workpieces and apply heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If convection-type reflow is used to bond solder bumps, then throughput is improved, but thermal budget increases causing warpage and delamination
Solution Approach 1:
The patent replaces the convection-based thermal field with a direct thermal contact system using a TCB bonding head. The bonding head makes intimate thermal contact with the die surface, enabling rapid heat transfer through conduction rather than convection. This substitution allows for faster heating rates and reduced thermal budget while maintaining bonding effectiveness.
Solution Approach 2:
The TCB bonding head serves as an intermediary between the heat source and the solder bumps. It directly contacts both the die and the substrate, facilitating controlled heat transfer and mechanical pressure application. This intermediary enables precise thermal management and eliminates the need for prolonged convection heating.
2Temperature
If thermal compressive reflow is used to reduce thermal budget, then warpage and delamination are reduced, but coplanarity deteriorates
Solution Approach 1:
The TCB bonding head dynamically adjusts its position and pressure during the bonding process. It maintains optimal contact pressure and height control throughout the reflow operation, adapting to variations in die and substrate surfaces. This dynamic control ensures consistent coplanarity of solder joints while maintaining low thermal budget.
Solution Approach 2:
The system incorporates feedback mechanisms to monitor and control the bonding parameters. The TCB bonding head position and pressure are controlled based on real-time measurements, ensuring that coplanarity requirements are met. This feedback control allows for precise adjustment of bonding conditions to achieve both low thermal budget and high coplanarity.
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 method enhances coplanarity and reduces warpage, ensuring improved connections between semiconductor chips and package substrates, facilitating better integration with printed circuit boards.
Implementation Method 1
a first substrate to a chuck through vacuum suction; attaching a second substrate to the chuck through vacuum suction
Implementation Method 2
heating the TCB head and the chuck to adhere the second conductive pillar to the second solder bump
Data Source
AI summary
A method includes attaching a die to a thermal compression bonding (TCB) head through vacuum suction, wherein the die comprises a plurality of conductive pillars, attaching a first substrate to a chuck through vacuum suction, wherein the first substrate comprises a plurality of solder bumps, contacting a first conductive pillar of the plurality of conductive pillars to a first solder bump of the plurality of solder bumps, wherein contacting the first conductive pillar to the first solder bump results in a first height between a topmost surface of the first conductive pillar and a bottommost surface of the first solder bump, and adhering the first solder bump to the first conductive pillar to form a first joint, wherein adhering the first solder bump to the first conductive pillar comprises heating the TCB head.